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Liang H, Wang S, Xu P, Wang M, Liang P, Wu S, Zhang J, Wong MH. Converting flooded rice to dry farming can alleviate MeHg accumulation in grains. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 283:116817. [PMID: 39083863 DOI: 10.1016/j.ecoenv.2024.116817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 07/22/2024] [Accepted: 07/27/2024] [Indexed: 08/02/2024]
Abstract
The study explored the impact of water management on rice cultivation in mercury-contaminated paddy soil. The objective was to analyze the characteristics of mercury translocation by converting flooded soils to dry farming (non-flooded) to alleviate mercury accumulation in rice grains. The experiment was conducted over three consecutive rice-growing seasons, employing two distinct water management models: a continuously flooded rice cultivation mode and a flooded rice planting mode in the first season, followed by a non-flooded rice farming mode in the second and third seasons. The results showed that the change from flooded to non-flooded rice cultivation patterns presented extremely excellent environmental potential for inhibiting the uptake of both methylmercury and total mercury in rice. When transitioning from flooded cultivation to dry farming, the concentration of methylmercury and total mercury in the grains of non-flooded rice decreased by 87.15 % and 9.57 %, respectively, compared to that in the grains of flooded rice. In the third season, the methylmercury and total mercury in the grains of non-flooded rice decreased further by 95.03 % and 69.45 %, respectively. This study verified that the conversion of rice cultivation from flooded to non-flooded is an efficient strategy for suppressing the accumulation of methylmercury in rice grains, and it might offer a promising solution for managing soil mercury risks and ensuring the safety of rice for human consumption.
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Affiliation(s)
- Huang Liang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China
| | - Shan Wang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; School of Geography and Resource Science, Neijiang Normal University, Neijiang 641100, China
| | - Ping Xu
- China National Rice Research Institute, Hangzhou 311401, China
| | - Minyan Wang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China.
| | - Peng Liang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; Zhejiang Province Key Laboratory of Soil Contamination and Bioremediation, Hangzhou 311300, China
| | - Shengchun Wu
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; Zhejiang Province Key Laboratory of Soil Contamination and Bioremediation, Hangzhou 311300, China
| | - Jin Zhang
- School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Ming Hung Wong
- Consortium on Health, Environment, Education, and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong Special Administrative Region of China
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Zhong H, Su Y, Wu X, Nunes L, Li C, Hao Y, Liu YR, Tang W. Mercury supply limits methylmercury production in paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:172335. [PMID: 38604369 DOI: 10.1016/j.scitotenv.2024.172335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/18/2024] [Accepted: 04/07/2024] [Indexed: 04/13/2024]
Abstract
The neurotoxic methylmercury (MeHg) is a product of inorganic mercury (IHg) after microbial transformation. Yet it remains unclear whether microbial activity or IHg supply dominates Hg methylation in paddies, hotspots of MeHg formation. Here, we quantified the response of MeHg production to changes in microbial activity and Hg supply using 63 paddy soils under the common scenario of straw amendment, a globally prevalent agricultural practice. We demonstrate that the IHg supply is the limiting factor for Hg methylation in paddies. This is because IHg supply is generally low in soils and can largely be facilitated (by 336-747 %) by straw amendment. The generally high activities of sulfate-reducing bacteria (SRB) do not limit Hg methylation, even though SRB have been validated as the predominant microbial Hg methylators in paddies in this study. These findings caution against the mobilization of legacy Hg triggered by human activities and climate change, resulting in increased MeHg production and the subsequent flux of this potent neurotoxin to our dining tables.
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Affiliation(s)
- Huan Zhong
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Yao Su
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Xinda Wu
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Luís Nunes
- Faculty of Sciences and Technology, Civil Engineering Research and Innovation for Sustainability Center, University of Algarve, Faro, Portugal
| | - Chengjun Li
- Institute of Environmental Research at Greater Bay Area, Guangzhou University, Guangzhou, Guangdong Province, China
| | - Yunyun Hao
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Wenli Tang
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
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3
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Liu JB, Zhou YJ, Du FZ, Man YB, Wong MH, Cheng Z. Human health risk assessment based on a total diet study of daily mercury intake in Chengdu, China. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2024; 46:138. [PMID: 38483661 DOI: 10.1007/s10653-024-01910-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 02/10/2024] [Indexed: 03/19/2024]
Abstract
To assess the total daily mercury intake and main exposure sources of residents, six food groups, including marine fish, freshwater fish, poultry, livestock, vegetables, and cereals, were collected from five districts of Chengdu, China. The median concentrations of total mercury (THg) and methylmercury (MeHg) were 12.8 and 6.94 μg kg-1 ww, respectively. Cereals (32.2%), vegetables (30.5%), and livestock (16.2%) contributed to a much larger extent to the total consumption for the participants in Chengdu. All food categories that contributed the most of THg (2.16 μg day-1) and MeHg 1.44 (μg day-1) to the daily intake in Chengdu were cereals and marine fish, respectively. The total Hazard Ratios values below 1 in this study indicate that there is no health risk associated with Hg ingestion from the consumption of these foods for the residents in Chengdu.
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Affiliation(s)
- Jun Bo Liu
- College of Environment, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China
| | - Ya Jun Zhou
- College of Environment, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China
| | - Fang Zhou Du
- College of Environment, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China
| | - Yu Bon Man
- Consortium on Health, Environment, Education, and Research (CHEER), and Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, Hong Kong, People's Republic of China
| | - Ming Hung Wong
- Consortium on Health, Environment, Education, and Research (CHEER), and Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, Hong Kong, People's Republic of China
| | - Zhang Cheng
- College of Environment, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China.
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4
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Cao H, Mao K, Zhang H, Wu Q, Ju H, Feng X. Thermal stability and micrdose-based coupling CRISPR/Cas12a biosensor for amplification-free detection of hgcA gene in paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168536. [PMID: 37977400 DOI: 10.1016/j.scitotenv.2023.168536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/21/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023]
Abstract
The lack of point-of-use (POU) methods hinders the utilization of the hgcA gene to rapidly evaluate methylmercury risks. CRISPR/Cas12a is a promising technology, but shortcomings such as low sensitivity, a strict reaction temperature and high background signal limit its further utilization. Here, a thermally stable microsystem-based CRISPR/Cas12a biosensor was constructed to achieve POU analysis for hgcA. First, three target gRNAs were designed to recognize hgcA. Then, a microsystem was developed to eliminate the background signal. Next, the effect of temperature on the activity of the Cas12a-gRNA complex was explored and its thermal stability was discovered. After that, coupling gRNA assay was introduced to improve sensitivity, exhibiting a limit of detection as low as 0.49 pM with a linear range of 0.98-125 pM, and a recovery rate between 90 and 110 % for hgcA. The biosensor was finally utilized to assess hgcA abundance in paddy soil, and high abundance of hgcA was found in these paddy soil samples. This study not only systematically explored the influence of temperature and microsystem on CRISPR/Cas12a, providing vital references for other novel CRISPR-based detection methods, but also applied the CRISPR-based analytical method to the field of environmental geochemistry for the first time, demonstrating enormous potential for POU detection in this field.
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Affiliation(s)
- Haorui Cao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kang Mao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Hua Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Qingqing Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huangxian Ju
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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Yin H, Yao H, Yuan W, Lin CJ, Fu X, Yin R, Meng B, Luo J, Feng X. Determination of the Isotopic Composition of Aqueous Mercury in a Paddy Ecosystem Using Diffusive Gradients in Thin Films. Anal Chem 2023; 95:12290-12297. [PMID: 37605798 DOI: 10.1021/acs.analchem.3c01356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Measuring the isotopic composition of Hg in natural waters is challenging due to the ultratrace level of aqueous Hg (ng L-1). At least 5 ng of Hg mass is required for Hg isotopic analysis. Given the low Hg concentration in natural waters, a large volume of water (>10 L) is typically needed. The conventional grab sampling method is time-consuming, laborious, and prone to contamination during transportation and preconcentration steps. In this study, a DGT (diffusive gradients in thin films) method based on aminopropyl and mercaptopropyl bi-functionalized SBA-15 nanoparticles was developed and extended to determine the concentration and isotopic composition of aqueous Hg for the first time. The results of laboratory analysis showed that Hg adsorption by DGT induces ∼ -0.2‰ mass-dependent fractionation (MDF) and little mass-independent fractionation (MIF). The magnitude of MDF exhibits a dependence on the diffusion-layer thickness of DGT. Since Hg-MDF can occur in a broad range of environmental processes, monitoring the δ202Hg of aqueous Hg using the DGT method should be performed with caution. Field results show consistent MIF signatures (Δ199Hg) between the DGT and conventional grab sampling method. The developed DGT method serves as a passive sampling method that effectively characterizes the MIF of Hg in waters to understand the biogeochemical cycle of Hg at contaminated sites.
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Affiliation(s)
- Hongqian Yin
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Yao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Wei Yuan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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6
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Zhang R, Aris-Brosou S, Storck V, Liu J, Abdelhafiz MA, Feng X, Meng B, Poulain AJ. Mining-impacted rice paddies select for Archaeal methylators and reveal a putative (Archaeal) regulator of mercury methylation. ISME COMMUNICATIONS 2023; 3:74. [PMID: 37454192 PMCID: PMC10349881 DOI: 10.1038/s43705-023-00277-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 07/18/2023]
Abstract
Methylmercury (MeHg) is a microbially produced neurotoxin derived from inorganic mercury (Hg), which accumulation in rice represents a major health concern to humans. However, the microbial control of MeHg dynamics in the environment remains elusive. Here, leveraging three rice paddy fields with distinct concentrations of Hg (Total Hg (THg): 0.21-513 mg kg-1 dry wt. soil; MeHg: 1.21-6.82 ng g-1 dry wt. soil), we resorted to metagenomics to determine the microbial determinants involved in MeHg production under contrasted contamination settings. We show that Hg methylating Archaea, along with methane-cycling genes, were enriched in severely contaminated paddy soils. Metagenome-resolved Genomes of novel putative Hg methylators belonging to Nitrospinota (UBA7883), with poorly resolved taxonomy despite high completeness, showed evidence of facultative anaerobic metabolism and adaptations to fluctuating redox potential. Furthermore, we found evidence of environmental filtering effects that influenced the phylogenies of not only hgcA genes under different THg concentrations, but also of two housekeeping genes, rpoB and glnA, highlighting the need for further experimental validation of whether THg drives the evolution of hgcAB. Finally, assessment of the genomic environment surrounding hgcAB suggests that this gene pair may be regulated by an archaeal toxin-antitoxin (TA) system, instead of the more frequently found arsR-like genes in bacterial methylators. This suggests the presence of distinct hgcAB regulation systems in bacteria and archaea. Our results support the emerging role of Archaea in MeHg cycling under mining-impacted environments and shed light on the differential control of the expression of genes involved in MeHg formation between Archaea and Bacteria.
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Affiliation(s)
- Rui Zhang
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Stéphane Aris-Brosou
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
- Department of Mathematics and Statistics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Veronika Storck
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, H3C 3A7, Canada
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Mahmoud A Abdelhafiz
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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7
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Xiao A, Chi Y, Huang L, Li WC, Ye Z. Effects of cultivar, water condition and their interactions on Cd accumulation in rice grains. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 262:115168. [PMID: 37352585 DOI: 10.1016/j.ecoenv.2023.115168] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 05/17/2023] [Accepted: 06/18/2023] [Indexed: 06/25/2023]
Abstract
Using low Cd accumulation cultivars and managing field water regimes are effective measures to mitigate Cd accumulations in rice grains. However, the effect of the cultivar-water condition interaction (CWI) on grain Cd accumulations has largely been ignored. To solve this problem, pot and hydroponic experiments were conducted using 14 rice cultivars and two contrasting water conditions. The results showed that CWI significantly affected Cd concentrations in rice grains and roots, explaining 8.8% and 22.8% of the total variance, respectively. These CWI effects were derived from cultivar-dependent variations in rhizosphere soil properties [Eh, pH and available Cd associated with root radial oxygen loss (ROL)] and root Cd uptake. In this context, cultivar HH61 exhibited low, stable Cd accumulations, owing to its stably lower translocation rate, root Cd uptake ability and available Cd in its rhizosphere than the other cultivars, which was induced by its lower ROL. Root-to-grain Cd translocation rates were vital in determining Cd accumulations in grain of different cultivars but were independent from CWI. These results indicated that CWI could play an important role in Cd accumulation in rice while stable low-Cd cultivar should possess low ROL under flooding and low root-to-grain Cd translocation rate. The results will provide novel theoretical basis for cultivar selection and hence benefit the extensive use of low-accumulation cultivars and public health.
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Affiliation(s)
- Anwen Xiao
- Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong Special Administrative Region of China
| | - Yihan Chi
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Lu Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China; Guangxi Colleges and Universities Key Laboratory of Environmental-friendly Materials and New Technology for Carbon Neutralization, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, School of Materials and Environment, Guangxi Minzu University, Nanning 530105, China
| | - Wai Chin Li
- Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong Special Administrative Region of China.
| | - Zhihong Ye
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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Wang Y, Chen L, Chen Y, Xue Y, Liu G, Zheng X, Zhou L, Zhong H. Effects of varying amounts of different biochars on mercury methylation in paddy soils and methylmercury accumulation in rice (Oryza sativa L.). THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162459. [PMID: 36871735 DOI: 10.1016/j.scitotenv.2023.162459] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/17/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
There is growing evidence for the potential of biochars (BCs) in remediating mercury-contaminated paddy soils, but the high doses commonly used in laboratory studies discourage BC application in practice. To address these difficulties, we compared the effects of varying amounts of BCs from different sources on the formation of methylmercury (MeHg) in soil and its accumulation in rice through microcosm and pot experiments. The addition of a wide range of added doses (0.3, 0.6, 1, 2, 4 and 5 %, w/w) of BCs derived from different biomass feedstocks (i.e., corn stalk, wheat straw, bamboo, oak and poplar) significantly decreased the fraction of ammonium thiosulfate ((NH4)2S2O3)-extractable MeHg in the soil, although the MeHg contents varied with BC types and doses during soil incubation. However, the extractable MeHg in the soil did not continuously decrease with increasing BC doses, especially at doses of >1 %, resulting in limited further reductions. Moreover, a relatively low application rate (0.3-0.6 %, w/w) of BCs (i.e., corn stalk, wheat straw and bamboo-derived BC), especially of bamboo-derived BCs, significantly decreased the MeHg levels (42-76 %) in rice grains (brown rice). Meanwhile, the extractable soil MeHg decreased (57-85 %), although the MeHg in the soil varied under BC amendment during rice cultivation. These results provide further evidence that applying BC produced from different raw carbon materials (e.g., lignocellulosic biomass) could effectively reduce MeHg accumulation in rice grains, possibly due to MeHg bioavailability reduction in the soil. Our results suggest the possibility of mitigating MeHg accumulation in rice with a low dose of BCs, with great potential for use in remediating moderately contaminated paddy soils.
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Affiliation(s)
- Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China; School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Li Chen
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Yuanyuan Chen
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Yongjun Xue
- School of Life Sciences, East China Normal University, Shanghai 200241, PR China
| | - Guangxia Liu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Xiangmin Zheng
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Limin Zhou
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China; School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai 200241, PR China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
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9
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Zhang J, Li C, Tang W, Wu M, Chen M, He H, Lei P, Zhong H. Mercury in wetlands over 60 years: Research progress and emerging trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 869:161862. [PMID: 36716881 DOI: 10.1016/j.scitotenv.2023.161862] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/04/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Wetlands are considered the hotspots for mercury (Hg) biogeochemistry, garnering global attention. Therefore, it is important to review the research progress in this field and predict future frontiers. To achieve that, we conducted a literature analysis by collecting 15,813 publications about Hg in wetlands from the Web of Science Core Collection. The focus of wetland Hg research has changed dramatically over time: 1) In the initial stage (i.e., 1959-1990), research mainly focused on investigating the sources and contents of Hg in wetland environments and fish. 2) For the next 20 years (i.e., 1991-2010), Hg transformation (e.g., Hg reduction and methylation) and environmental factors that affect Hg bioaccumulation have attracted extensive attention. 3) In the recent years of 2011-2022, hot topics in Hg study include microbial Hg methylators, Hg bioavailability, methylmercury (MeHg) demethylation, Hg stable isotope, and Hg cycling in paddy fields. Finally, we put forward future research priorities, i.e., 1) clarifying the primary factors controlling MeHg production, 2) uncovering the MeHg demethylation process, 3) elucidating MeHg bioaccumulation process to better predict its risk, and 4) recognizing the role of wetlands in Hg circulation. This research shows a comprehensive knowledge map for wetland Hg research and suggests avenues for future studies.
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Affiliation(s)
- Jin Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Chengjun Li
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
| | - Wenli Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mengjie Wu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mingying Chen
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Huan He
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Pei Lei
- School of Environment, Nanjing Normal University, Nanjing 210023, China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario, Canada
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10
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Lv D, Wu Q, Ouyang D, Wen M, Zhang G, Wang S, Duan L. Differentiated emission control strategy based on comprehensive evaluation of multi-media pollution: Case of mercury emission control. J Environ Sci (China) 2023; 123:222-234. [PMID: 36521986 DOI: 10.1016/j.jes.2022.03.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 06/17/2023]
Abstract
In order to comprehensively evaluate the environmental impact of multi-media mercury pollution under differentiated emission control strategies in China, a literature review and case studies were carried out. Increased human exposure to methylmercury was assessed through the dietary intake of residents in areas surrounding a typical coal-fired power plant and a zinc (Zn) smelter, located either on acid soil with paddy growth in southern China, or on alkaline soil with wheat growth in northern China. Combined with knowledge on speciated mercury in flue gas and the fate of mercury in the wastewater or solid waste of the typical emitters applying different air pollution control devices, a simplified model was developed by estimating the incremental daily intake of methylmercury from both local and global pollution. Results indicated that air pollution control for coal-fired power plants and Zn smelters can greatly reduce health risks from mercury pollution, mainly through a reduction in global methylmercury exposure, but could unfortunately induce local methylmercury exposure by transferring more mercury from flue gas to wastewater or solid waste, then contaminating surrounding soil, and thus increasing dietary intake via crops. Therefore, tightening air emission control is conducive to reducing the comprehensive health risk, while the environmental equity between local and global pollution control should be fully considered. Rice in the south tends to have higher bioconcentration factors than wheat in the north, implying the great importance of strengthening local pollution control in the south, especially for Zn smelters with higher contribution to local pollution.
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Affiliation(s)
- Dongwei Lv
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Qingru Wu
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China
| | - Daiwei Ouyang
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Minneng Wen
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Gehui Zhang
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Shuxiao Wang
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China
| | - Lei Duan
- State Key Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China.
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11
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Li H, Li Y, Tang W, Zhong H, Zhao J, Bai X, Sha S, Xu D, Lei P, Gao Y. Assessment of the Bioavailability of Mercury Sulfides in Paddy Soils Using Sodium Thiosulfate Extraction - Results from Microcosm Experiments. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 109:764-770. [PMID: 35305130 DOI: 10.1007/s00128-022-03483-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Mercury sulfides (HgS), one of the largest Hg sinks in the lithosphere, has long been considered to be highly inert. Recently, several HgS speciation (e.g., nano- or micro-sized HgS particles) in paddy soils have been found to be reactive and bioavailable, increasing the possibility of methylation and bioaccumulation and posing a potential risk to humans. However, a simple and uniform method for investigating HgS bioavailability is still lacking. To address this issue, we extracted dissolved Hg from HgS particles by sodium thiosulfate (Na2S2O3) in paddy soils and analyzed the correlation between extracted Hg and soil methylmercury (MeHg). Results showed that the amounts of Hg extracted by Na2S2O3 had a strong positive correlation with the levels of soil MeHg (R 2 adj = 0.893, p < 0.05). It is suggested that Na2S2O3 extraction may be a good method of predicting Hg bioavailability in paddy soils. Our results would help to give clues in better predicting Hg risk in natural environments.
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Affiliation(s)
- Hong Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
- Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
| | - Yunyun Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
| | - Wenli Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, 210023, Nanjing, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, 210023, Nanjing, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
| | - Xu Bai
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Shengnan Sha
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Diandou Xu
- Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China
| | - Pei Lei
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, 210023, Nanjing, China.
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, 100049, Beijing, China.
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12
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Wang J, Xiang Y, Tian X, Zhang C, Gong G, Xue J, Jiang T, Wang D, Wang Y. Role of the rhizosphere of a flooding-tolerant herb in promoting mercury methylation in water-level fluctuation zones. J Environ Sci (China) 2022; 119:139-151. [PMID: 35934459 DOI: 10.1016/j.jes.2022.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/26/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
The water-level fluctuation zone (WLFZ) has been considered as a hotspot for mercury (Hg) methylation. Flooding-tolerant herbs are gradually acclimated to this water-land ecotone, tending to form substantial root systems for improving erosion resistance. Accompanying rhizosphere microzone plays crucial but unclear roles in methylmercury (MeHg) formation in the WLFZ. Thus, we conducted this study in the WLFZ of the Three Gorges Reservoir, to explore effects of the rhizosphere of a dominant flooding-tolerant herb (bermudagrass) on MeHg production. The elevated Hg and MeHg in rhizosphere soils suggest that the rhizosphere environment provides favorable conditions for Hg accumulation and methylation. The increased bioavailable Hg and microbial activity in the rhizosphere probably serve as important factors driving MeHg formation in the presence of bermudagrass. Simultaneously, the rhizosphere environments changed the richness, diversity, and distribution of hgcA-containing microorganisms. Here, a typical iron-reducing bacterium (Geobacteraceae) has been screened, however, the majority of hgcA genes detected in rhizosphere, near-, and non-rhizosphere soils of the WLFZ were unclassified. Collectively, these results provide new insights into the elevated MeHg production as related to microbial processes in the rhizosphere of perennial herbs in the WLFZ, with general implications for Hg cycling in other ecosystems with water-level fluctuations.
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Affiliation(s)
- Juan Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology & Health Effect, Chinese Academy of Sciences, Research Center for Eco-Environmental Sciences, Beijing 100085, China
| | - Xiaosong Tian
- College of Resources and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China
| | - Cheng Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Guiqing Gong
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Jinping Xue
- Institut des Sciences Analytiques et des Physico-Chimie pour l'Environnement et les Matériaux (IPREM), UMR 5254, CNRS, Université de Pau et des Pays de l'Adour, Pau 64000, France
| | - Tao Jiang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
| | - Yongmin Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
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13
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Tang W, Tang C, Lei P. Sulfur-driven methylmercury production in paddies continues following soil oxidation. J Environ Sci (China) 2022; 119:166-174. [PMID: 35934461 DOI: 10.1016/j.jes.2022.07.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/09/2022] [Accepted: 07/10/2022] [Indexed: 06/15/2023]
Abstract
Methylmercury (MeHg) production in paddy soils and its accumulation in rice raise global concerns since rice consumption has been identified as an important pathway of human exposure to MeHg. Sulfur (S) amendment via fertilization has been reported to facilitate Hg methylation in paddy soils under anaerobic conditions, while the dynamic of S-amendment induced MeHg production in soils with increasing redox potential remains unclear. This critical gap hinders a comprehensive understanding of Hg biogeochemistry in rice paddy system which is characterized by the fluctuation of redox potential. Here, we conducted soil incubation experiments to explore MeHg production in slow-oxidizing paddy soils amended with different species of S and doses of sulfate. Results show that the elevated redox potential (1) increased MeHg concentrations by 10.9%-35.2%, which were mainly attributed to the re-oxidation of other S species to sulfate and thus the elevated abundance of sulfate-reducing bacteria, and (2) increased MeHg phytoavailability by up to 75% due to the reductions in acid volatile sulfide (AVS) that strongly binds MeHg in soils. Results obtained from this study call for attention to the increased MeHg production and phytoavailability in paddy soils under elevated redox potentials due to water management, which might aggravate the MeHg production induced by S fertilization and thus enhance MeHg accumulation in rice.
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Affiliation(s)
- Wenli Tang
- School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China.
| | - Chao Tang
- School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China
| | - Pei Lei
- School of Environment, Nanjing Normal University, Nanjing 210023, China.
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14
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Li K, Wang C, Ow DW. Root microbiome changes associated with cadmium exposure and/or overexpression of a transgene that reduces Cd content in rice. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 237:113530. [PMID: 35462194 DOI: 10.1016/j.ecoenv.2022.113530] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 03/09/2022] [Accepted: 04/14/2022] [Indexed: 06/14/2023]
Abstract
Cadmium (Cd) is a toxic heavy metal that can accumulate in crop plants. We reported previously the engineering of a low cadmium-accumulating line (2B) of rice through overexpression of a truncated OsO3L2 gene. As expression of this transgene was highest in plant roots, amplicon and metatranscriptome sequencing were used to investigate the possibility that its expression affects root associated microbes. Based on amplicon sequencing of bacterial 16S rRNA, but less so from fungal ITS, the OTUs (operational taxonomic units) showed less diversity in soil tightly (rhizoplane) than loosely (rhizosphere) associated with plant roots. Significantly changed OTUs caused by the low-Cd accumulating plant 2B, Cd treatment or both were found, and 10 of the 13 OTUs (77%) that were enriched in Cd treated 2B samples over the wild type counterpart have been previously described as involved in tolerance to Cd or other heavy metals. Metatranscriptome sequencing of rhizosphere microbiome found that bacteria accounted for 70-75% of the microbial RNA. Photosynthesis-antenna proteins and nitrogen metabolism pathways were most active in soil microbes treated with Cd and grown with plant 2B. Correspondingly, the relative abundance of Cyanobacteria was enriched to < 1% of Cd treated rhizosphere bacteria, yet accounted for up to 13% of Cd treated 2B rhizospheric transcripts. These enriched microbes by transgene and Cd are worthy candidates for future application on reducing crop uptake of Cd.
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Affiliation(s)
- Kangjia Li
- Plant Gene Engineering Center, Chinese Academy of Sciences Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Changhu Wang
- Plant Gene Engineering Center, Chinese Academy of Sciences Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
| | - David W Ow
- Plant Gene Engineering Center, Chinese Academy of Sciences Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
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15
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Liu J, Lu B, Poulain AJ, Zhang R, Zhang T, Feng X, Meng B. The underappreciated role of natural organic matter bond Hg(II) and nanoparticulate HgS as substrates for methylation in paddy soils across a Hg concentration gradient. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 292:118321. [PMID: 34634402 DOI: 10.1016/j.envpol.2021.118321] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/07/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
Rice consumption is the major pathway for human methylmercury (MeHg) exposure in inland China, especially in mercury (Hg) contaminated regions. MeHg production, a microbially driven process, depends on both the chemical speciation of inorganic divalent mercury, Hg(II), that determines Hg bioavailability for methylation. Studies have shown that Hg(II) speciation in contaminated paddy soils is mostly controlled by natural organic matter and sulfide levels, which are typically thought to limit Hg mobility and bioavailability. Yet, high levels of MeHg are found in rice, calling for reconsideration of the nature of Hg species bioavailable to methylators in paddy soils. Here, we conducted incubation experiments using a multi-isotope tracer technique including 198Hg(NO3)2, natural organic matter bond Hg(II) (NOM-199Hg(II)), ferrous sulfide sorbed Hg(II) (≡FeS-200Hg(II)), and nanoparticulate mercuric sulfide (nano-202HgS), to investigate the relative importance of geochemically diverse yet relevant Hg(II) species on Hg methylation in paddy soils across a Hg concentration gradient. We show that methylation rates for all Hg(II) species tested decreased with increasing Hg concentrations, and that methylation rates using NOM-199Hg(II) and nano-202HgS as substrates were similar or greater than rates obtained using the labile 198Hg(NO3)2 substrate. ≡FeS-200Hg(II) yielded the lowest methylation rate in all sites, and thus the formation of FeS is likely a sink for labile 198Hg(NO3)2 in sulfide-rich paddy soils. Moreover, the variability in the methylation data for a given site (1 to 5-fold variation depending on the Hg species) was smaller than what was observed across the Hg concentration gradient (103-104 fold variation between sites). These findings emphasize that at broad spatial scales, site-specific characteristics, such as microbial community structure, need to be taken into consideration, alongside the nature of the Hg substrate available for methylation, to determine net MeHg production. This study highlights the importance of developing site-specific strategies for remediating Hg pollution.
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Affiliation(s)
- Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Benqi Lu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Alexandre J Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Rui Zhang
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin, 300350, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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16
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Enamorado-Montes G, Reino-Causil B, Urango-Cardenas I, Marrugo-Madrid S, Marrugo-Negrete J. Mercury Accumulation in Commercial Varieties of Oryza sativa L. Cultivated in Soils of La Mojana Region, Colombia. TOXICS 2021; 9:304. [PMID: 34822695 PMCID: PMC8624091 DOI: 10.3390/toxics9110304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/16/2021] [Accepted: 11/02/2021] [Indexed: 02/07/2023]
Abstract
The Hg accumulation in different commercial varieties of Oryzasativa L. was evaluated in the region of La Mojana, Colombia, where rice cultivation has become the staple food of the population living in this area. The varieties studied were Fedearroz-473 (FA473), Fedearroz-2000 (FA2000), and Fedearroz-Mocari (FAM). Soil spiked at different Hg levels was evaluated, (130, 800, and 1500 µg kg-1) using a 32 factorial design that consisted of 3 (rice varieties) × 3 (Hg contents). The biomass, 1000-grain weight, and the accumulation of Hg in the roots, grains, and husks were determined. The highest biomass was found in the FA473 (308.76 ± 108.26 g), and the lowest was found in FAM (144.04 ± 26.45 g) in the 1500 µg kg-1 Hg soil in both cases. The weight per 1000-grains decreased significantly in the soil containing 800 µg of Hg kg-1. Hg accumulation in the organs of the evaluated varieties was higher in the roots, followed by in the husks and grains. The Hg in the rice grains of the evaluated varieties presented levels close to the permissible limit of the Chinese standard (20 μg Hg kg-1) in the evaluated soils and were only exceeded by FA473. Although in natural soil concentrations, the non-cancer health risk (HQ) from rice consumption was lower for FA473 and FAM; Hg enrichment in the soil of La Mojana region may endanger the health of future populations due to their high consumption of rice.
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Affiliation(s)
| | | | | | | | - José Marrugo-Negrete
- Departamento de Química, Laboratorio de Toxicología y gestión ambiental, Facultad de Ciencias Básicas, Universidad de Córdoba, Carrera 6 No. 77-305, Montería 230002, Córdoba, Colombia; (G.E.-M.); (B.R.-C.); (I.U.-C.); (S.M.-M.)
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17
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Hyun HR, Yoon H, Lyou ES, Kim JJ, Kwon SY, Lee TK. Short-Term Legacy Effects of Mercury Contamination on Plant Growth and nifH-Harboring Microbial Community in Rice Paddy Soil. MICROBIAL ECOLOGY 2021; 82:932-941. [PMID: 33624137 DOI: 10.1007/s00248-021-01722-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Methylmercury (MeHg), which is formed in rice paddy soil, exhibits strong neurotoxicity through bioaccumulation in the food chain. A few groups of microorganisms drive both mercury methylation and nitrogen fixation in the rhizosphere. Little is known about how the shifted soil microbial community by Hg contamination affects nitrogen fixation rate and plant growth in paddy soil. Here, we examined how stimulated short-term Hg amendment affects the nitrogen fixing microbial community and influences plant-microbe interactions. Soil was treated with low (0.2 mg/kg) and high (1.1 mg/kg) concentrations of Hg for 4 weeks; then, rice (Oryza sativa) was planted and grown for 12 weeks. The nitrogen-fixation rate and rice growth were measured. The diversity and structure of the microbial community were analyzed by sequencing the nifH gene before and after rice cultivation. Hg treatments significantly decreased the nitrogen fixation rate and dry weight of the rice plants. The structure of the nifH-harboring community was remarkably changed after rice cultivation depending on Hg treatments. Iron- or sulfate-reducing bacteria, including Desulfobacca, Desulfoporosimus, and Geobacter, were observed as legacy response groups; their abundances increased in the soil after Hg treatment. The high abundance of those groups were maintained in control, but the abundance drastically decreased after rice cultivation in the soil treated with Hg, indicating that symbiotic behavior of rice plants changes according to the legacy effects on Hg contamination. These results suggested that Hg contamination can persist in soil microbial communities, affecting their nitrogen-fixation ability and symbiosis with rice plants in paddy soil.
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Affiliation(s)
- Hye Rim Hyun
- Department of Environmental Engineering, Yonsei University, Wonju, Republic of Korea
| | - Hakwon Yoon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Eun Sun Lyou
- Department of Environmental Engineering, Yonsei University, Wonju, Republic of Korea
| | - Jin Ju Kim
- Department of Systems Biotechnology, Chun-Ang University, Anseong, Republic of Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Tae Kwon Lee
- Department of Environmental Engineering, Yonsei University, Wonju, Republic of Korea.
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18
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Sánchez-Fortún M, Vinyoles D, López-Carmona S, Carrasco JL, Sanpera C. Effect of different rice farming practices on the bioavailability of mercury: A mesocosm experiment with common goldfish (Carassius auratus). ENVIRONMENTAL RESEARCH 2021; 201:111486. [PMID: 34129865 DOI: 10.1016/j.envres.2021.111486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/30/2021] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Wetlands such as rice paddies are important ecosystems that provide habitat for a numerous range of species but are considered as a major source of mercury in the most toxic form of methylmercury. An in situ mesocosm experiment was conducted during the rice cultivation season of 2018 in rice paddies from the Ebro Delta (NE Spain) to investigate the bioaccumulation of mercury in fish. Common goldfish (Carassius auratus) were exposed to three types of rice-fields subject to different agricultural management (conventional or ecological agriculture) and different hydric practices (wet, dry) and were sampled monthly. Total mercury concentration in fish increased over time for almost all the fields under study, but the mercury increase was particularly higher for fish exposed to ecological fields. We conducted δ15N and δ13C measurements to follow up fish diet changes within or among fields. The results have shown there were no variations in the diet of the fish over time within fields, although differences among management practices were observed, which could explain to some extent the THg variation in fish exposed to each of the agricultural practices. Results indicate that wetting and drying rice fields might be a greater source of mercury for fish and a potential hotspot for MeHg production enhanced by physicochemical parameters. Thus, mercury bioaccumulation in fish inhabiting rice paddies depend on several factors what, in turn, could lead to biomagnification across the food webs.
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Affiliation(s)
- Moisès Sánchez-Fortún
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain.
| | - Dolors Vinyoles
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain
| | - Sophie López-Carmona
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; UFR Sciences et Techniques, Université de Nantes, Nantes, France
| | - Josep Lluís Carrasco
- Biostatistics, Department of Basic Clinical Practice, University of Barcelona, Barcelona, Spain
| | - Carola Sanpera
- Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), University of Barcelona, Barcelona, Spain
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19
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Huang L, Wang X, Chi Y, Huang L, Li WC, Ye Z. Rhizosphere bacterial community composition affects cadmium and arsenic accumulation in rice (Oryza sativa L.). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 222:112474. [PMID: 34214770 DOI: 10.1016/j.ecoenv.2021.112474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
Cadmium (Cd) and arsenic (As) contamination in paddy soils poses serious health risks to humans. The accumulation of Cd and As in rice (Oryza sativa L.) depends on their bioavailability, which is affected by soil physicochemical properties and soil microbial activities. However, little is known about the intricate interplay between rice plants and their rhizosphere microbes during the uptake of Cd and As. In this study, different bacterial communities were established by sterilizing paddy soils with γ-radiation. A pot experiment using two paddy soils with different levels of contamination was conducted to explore how the bacterial community composition affects Cd and As accumulation in rice plants. The results showed that the sterilization treatment substantially changed the bacterial composition in the rhizosphere, and significantly increased the grain yield (by 33.5-38.3%). The sterilization treatment resulted in significantly decreased concentrations of Cd (by 18.2-38.7%) and As (by 20.3-36.7%) in the grain, straw, and root of rice plants. The accumulation of Cd and As in rice plants was negatively correlated with the relative abundance of sulfate-reducing bacteria and iron-oxidizing bacteria in the rhizosphere. Other specific taxa associated with the accumulation of Cd and As in rice plants were also identified. Our results suggest that regulating the composition of the rhizosphere bacterial community could simultaneously reduce Cd and As accumulation in rice grain and increase the grain yield. These results would be useful for developing strategies to cultivate safe rice crops in areas contaminated with Cd and As.
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Affiliation(s)
- Lu Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Xun Wang
- College of Marine Sciences, South China Agricultural University, Guangzhou 510642, China.
| | - Yihan Chi
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Linan Huang
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Wai Chin Li
- Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, China.
| | - Zhihong Ye
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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20
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Wang J, Shaheen SM, Jing M, Anderson CWN, Swertz AC, Wang SL, Feng X, Rinklebe J. Mobilization, Methylation, and Demethylation of Mercury in a Paddy Soil Under Systematic Redox Changes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10133-10141. [PMID: 34210118 DOI: 10.1021/acs.est.0c07321] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Methylmercury (MeHg) contamination in paddy fields is a significant environmental issue globally since over half of the population of our planet consumes rice. MeHg is a neurotoxin produced by microorganisms in oxygen-limited environments. Microbial effect on MeHg production is a hotspot of research; however, it has been largely ignored how the oxidation-reduction potential (Eh) shapes MeHg formation. Here, we elucidated Hg (de)-methylation in a contaminated soil by increasing Eh stepwise from -300 to +300 mV using a sophisticated biogeochemical microcosm. At the Eh range from -300 to -100 mV, high MeHg concentration and dissolved total Hg (THg) concentration were found due to a high relative abundance of Hg-methylation bacteria (e.g., Desulfitobacterium spp.), acidification, and reductive dissolution of Fe(oxyhydr)oxides. At the Eh range from 0 to +200 mV, the formation of colloids leads to adsorption of Hg and as a result colloidal Hg increased. MeHg reduction with Eh (-300 to +200 mV) increase was mainly attributed to a reduced Hg methylation, as dissolved THg and relative abundance of Desulfitobacterium spp. decreased by 50 and 96%, respectively, at Eh of +200 mV as compared to Eh of -300 mV. Mercury demethylation might be less important since the relative abundance of demethylation bacteria (Clostridium spp.) also decreased over 93% at Eh of +200 mV. These new results are crucial for predicting Hg risks in paddy fields.
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Affiliation(s)
- Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550082, P. R. China
- Laboratory of Soil- and Groundwater-Management, Institute of Foundation Engineering, Water- and Waste-Management, School of Architecture and Civil Engineering, University of Wuppertal, Pauluskirchstraße 7, 42285 Wuppertal, Germany
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, P. R. China
| | - Sabry M Shaheen
- Laboratory of Soil- and Groundwater-Management, Institute of Foundation Engineering, Water- and Waste-Management, School of Architecture and Civil Engineering, University of Wuppertal, Pauluskirchstraße 7, 42285 Wuppertal, Germany
- Department of Arid Land Agriculture, Faculty of Meteorology, Environment, and Arid Land Agriculture, King Abdulaziz University, Jeddah 21589, Kingdom of Saudi Arabia
- Department of Soil and Water Sciences, Faculty of Agriculture, University of Kafrelsheikh, 33516 Kafr El-Sheikh, Egypt
| | - Min Jing
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550082, P. R. China
| | - Christopher W N Anderson
- Environmental Sciences, School of Agriculture and Environment, Massey University, 4442 Palmerston North, New Zealand
| | - Ann-Christin Swertz
- Department of Safety Technology and Environmental Protection, Faculty of Mechanical Engineering and Safety Engineering, University of Wuppertal, Rainer-Gruenter-Straße, 42119 Wuppertal, Germany
| | - Shan-Li Wang
- Department of Agricultural Chemistry, National Taiwan University, Taipei 106, Taiwan, Republic of China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550082, P. R. China
- CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, P. R. China
| | - Jörg Rinklebe
- Laboratory of Soil- and Groundwater-Management, Institute of Foundation Engineering, Water- and Waste-Management, School of Architecture and Civil Engineering, University of Wuppertal, Pauluskirchstraße 7, 42285 Wuppertal, Germany
- Department of Environment, Energy and Geoinformatics, University of Sejong, 98 Gunja-Dong, Guangjin-Gu, Seoul 05006, Republic of Korea
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21
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Zhang P, Guo Z, Monikh FA, Lynch I, Valsami-Jones E, Zhang Z. Growing Rice ( Oryza sativa) Aerobically Reduces Phytotoxicity, Uptake, and Transformation of CeO 2 Nanoparticles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:8654-8664. [PMID: 34156836 DOI: 10.1021/acs.est.0c08813] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This study compared the impact and uptake of root-administered CeO2 nanoparticles (NPs) in rice growing under flooded and aerobic soil conditions, which are two water regimes commonly used for rice cultivation. CeO2 NPs at 100 mg/kg improved photosynthesis and plant growth by reducing the oxidative damage and enhancing plant tolerance to stress, while a higher concentration (500 mg/kg) of CeO2 NPs negatively affected plant growth. More significant effects were observed under the flooded condition than under the aerobic condition. CeO2 NPs of 100 and 500 mg/kg resulted in 78% and 70% higher accumulation of Ce in shoots under the flooded condition compared to the aerobic condition. CeO2 NPs partially transformed to Ce(III) species in soils and plants under both conditions. A higher extent of transformation under the flooded condition, which was partly attributed to the lower soil pH and redox potential under the flooded condition, leads to higher plant uptake of Ce. A higher extent of transformation in rhizosphere soil was observed. A higher plant transpiration rate (TR) under flooded conditions resulted in a higher accumulation of CeO2 species in shoots. This study, for the first time, reported that water regimes influenced the biotransformation of CeO2 NPs and their uptake and impact in rice plants.
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Affiliation(s)
- Peng Zhang
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Zhiling Guo
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Fazel Abdolahpur Monikh
- Department of Environmental & Biological Sciences, University of Eastern Finland, P.O. Box 111, Joensuu FI-80101, Finland
| | - Iseult Lynch
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Eugenia Valsami-Jones
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Zhiyong Zhang
- Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
- School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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22
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Stable isotope tracers identify sources and transformations of mercury in rice (Oryza sativa L.) growing in a mercury mining area. FUNDAMENTAL RESEARCH 2021. [DOI: 10.1016/j.fmre.2021.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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23
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Du H, Guo P, Wang T, Ma M, Wang D. Significant bioaccumulation and biotransformation of methyl mercury by organisms in rice paddy ecosystems: A potential health risk to humans. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 273:116431. [PMID: 33453697 DOI: 10.1016/j.envpol.2021.116431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/13/2020] [Accepted: 12/31/2020] [Indexed: 06/12/2023]
Abstract
Rice has been confirmed as one of the principal intake pathways for methylmercury (MeHg) in human, however, the impact of edible organisms, such as snails, loaches and eels, living in the rice-based ecosystem to the overall MeHg intake has been overlooked. Here, we conducted a cross-sectional ecological study, and the results showed that bioaccumulation of MeHg in these edible organisms was significantly higher than in paddy soils and rice roots (p < 0.001), even though rice roots and grains have significantly higher total Hg (THg) (p < 0.001). The MeHg/THg ratios were consistently and significantly higher in those edible organisms than in rice grains, suggesting a potential elevated MeHg exposure risk through consumption. Based on results of bioaccumulation factors (BAFs) for MeHg, it was clear that MeHg was bioaccumulated and biotransformed from paddy soils to earthworms and then to eels, as well as from paddy soils to snails and then to eels and loaches, potentially indicating that the consumption of eels and loaches was absolutely pernicious to people regularly feeding on them. Overall, MeHg was biomagnified along the food chain of the paddy ecosystem from soil to the organisms, and it was of potential higher risks for local residents to eat them, especially eels and loaches. Therefore, it is intensely indispensable for people fond of such diets to attenuate their consumption of rice, eels and loaches, thus mitigating their MeHg exposure risks.
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Affiliation(s)
- Hongxia Du
- Chongqing Key Laboratory of Bio-resource for Bioenergy, Southwest University, College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Pan Guo
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Tao Wang
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Ming Ma
- Chongqing Key Laboratory of Bio-resource for Bioenergy, Southwest University, College of Resources and Environment, Southwest University, Chongqing, 400715, China; Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, 400715, China.
| | - Dingyong Wang
- Chongqing Key Laboratory of Bio-resource for Bioenergy, Southwest University, College of Resources and Environment, Southwest University, Chongqing, 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing, 400715, China
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24
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Jose A, Nanjan P, Porel M. Sequence-defined oligomer as a modular platform for selective sub-picomolar detection and removal of Hg 2+. Polym Chem 2021. [DOI: 10.1039/d1py00642h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A modular synthetic platform for selective sensing and removal of Hg2+ was developed.
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Affiliation(s)
- Anna Jose
- Discipline of Chemistry, Indian Institute of Technology Palakkad, Kerala-678577, India
| | - Pandurangan Nanjan
- Discipline of Chemistry, Indian Institute of Technology Palakkad, Kerala-678577, India
| | - Mintu Porel
- Discipline of Chemistry, Indian Institute of Technology Palakkad, Kerala-678577, India
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25
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Wang Y, Sun Y, He T, Deng H, Wang Z, Wang J, Zheng X, Zhou L, Zhong H. Biochar amendment mitigates the health risks of dietary methylmercury exposure from rice consumption in mercury-contaminated areas. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115547. [PMID: 33254602 DOI: 10.1016/j.envpol.2020.115547] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 06/12/2023]
Abstract
The accumulation of methylmercury (MeHg) in rice is an important MeHg exposure pathway in humans in several mercury (Hg)-contaminated areas. In this study, the effects of low-dose biochar (BC) amendment (0.3%, w/w) on MeHg mobility/phytoavailability in different Hg-contaminated paddy soils, MeHg accumulation in rice plants and the health risks associated with MeHg-laden rice consumption were investigated. Soils amended with different doses of bamboo-derived BC (0.3, 0.5, and 1%, w/w) were incubated under anoxic conditions in microcosm experiments. In addition, pot experiments were conducted involving rice cultivation with a low BC application rate (0.3%, w/w). We observed that (1) the fraction of extractable MeHg in soils decreased with BC addition in both the microcosm and pot experiments; (2) MeHg concentrations in the rice grains (brown rice) significantly decreased by 56-88% in response to BC amendment, which may be attributed mainly to decreases in MeHg mobility/phytoavailability in the soil; and (3) the hazard quotient (HQ) values for adults and children and fetal intelligence quotient (IQ) decrements associated with MeHg-laden rice consumption were significantly alleviated under BC amendment. Taken together, our findings suggest that a low dose of BC (0.3%, w/w) could have great potential for mitigating the health risks of dietary MeHg exposure from the consumption of rice grown in mercury (Hg)-contaminated areas.
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Affiliation(s)
- Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Yafei Sun
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Tianrong He
- Key Laboratory of Karst Environment and Geohazard Prevention, Guizhou University, Guiyang, 550003, PR China
| | - Hong Deng
- Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China; Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Technology Innovation Center for Land Spatial Eco-restoration in Metropolitan area, Ministry of Natural Resource, School of Ecological and Environmental Science, East China Normal University, Shanghai, 200241, PR China
| | - Zhigang Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Jiangtao Wang
- Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Xiangmin Zheng
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Limin Zhou
- Key Laboratory of Geographic Information Science, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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26
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Tang Z, Fan F, Deng S, Wang D. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110950. [PMID: 32800226 DOI: 10.1016/j.ecoenv.2020.110950] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.
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Affiliation(s)
- Zhenya Tang
- Faculty of Environmental Science & Engineering, Kunming University of Science &Technology, Kunming, China; Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China.
| | - Fangling Fan
- School of Energy and Environment Science, Yunnan Normal University, Kunming, China.
| | - Shiping Deng
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK, USA.
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China; State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing, China.
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27
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Bishop K, Shanley JB, Riscassi A, de Wit HA, Eklöf K, Meng B, Mitchell C, Osterwalder S, Schuster PF, Webster J, Zhu W. Recent advances in understanding and measurement of mercury in the environment: Terrestrial Hg cycling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 721:137647. [PMID: 32197286 DOI: 10.1016/j.scitotenv.2020.137647] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/23/2020] [Accepted: 02/28/2020] [Indexed: 06/10/2023]
Abstract
This review documents recent advances in terrestrial mercury cycling. Terrestrial mercury (Hg) research has matured in some areas, and is developing rapidly in others. We summarize the state of the science circa 2010 as a starting point, and then present the advances during the last decade in three areas: land use, sulfate deposition, and climate change. The advances are presented in the framework of three Hg "gateways" to the terrestrial environment: inputs from the atmosphere, uptake in food, and runoff with surface water. Among the most notable advances: These and other advances reported here are of value in evaluating the effectiveness of the Minamata Convention on reducing environmental Hg exposure to humans and wildlife.
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Affiliation(s)
- Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | | | - Ami Riscassi
- Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesville, VA 22904-4123, USA.
| | - Heleen A de Wit
- Norwegian Institute for Water Research, Gaustadalléen 21, NO-0349, Norway.
| | - Karin Eklöf
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden.
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
| | - Carl Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
| | - Stefan Osterwalder
- Institut des Géosciences de l'Environnement, Université Grenoble Alpes, CNRS, IRD, Grenoble 18 INP, 38000 Grenoble, France.
| | - Paul F Schuster
- U.S. Geological Survey, 3215 Marine Street, Suite E-127, Boulder, CO 80303-1066, USA.
| | - Jackson Webster
- Department of Civil Engineering, California State University, 400 W. 1st Street, 21 95929-0930 Chico, CA, USA.
| | - Wei Zhu
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
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28
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Zhao L, Meng B, Feng X. Mercury methylation in rice paddy and accumulation in rice plant: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110462. [PMID: 32179234 DOI: 10.1016/j.ecoenv.2020.110462] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/07/2020] [Accepted: 03/08/2020] [Indexed: 06/10/2023]
Abstract
The bioavailability and toxicity of mercury (Hg) are dependent on its chemical speciation, in which methylmercury (MeHg) is the most toxic compound. Inorganic Hg can be transformed into MeHg in anaerobic conditions. Subsequent accumulation and biomagnification in the food chain pose a potential threat to human health. Previous studies have confirmed that paddy soil is an important site for MeHg production, and rice fields are an important source of MeHg in terrestrial ecosystems. Rice (Oryza sativa L.) is recently confirmed as a potential bioaccumulator plant of MeHg. Understanding the behaviour of Hg in rice paddies is important, particularly the mechanisms involved in Hg sources, uptake, toxicity, detoxification, and accumulation in crops. This review highlights the issue of MeHg-contaminated rice, and presents the current understanding of the Hg cycling in the rice paddy ecosystem, including the mechanism and processes of Hg species accumulation in rice plants and Hg methylation/demethylation processes in rice paddies and the primary controlling factors. The review also identified various research gaps in previous studies and proposes future research objectives to reduce the impact of Hg-contamination in rice crops.
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Affiliation(s)
- Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang, 550025, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
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29
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Kodamatani H, Daiba Y, Morisaki S, Ichitani K, Kanzaki R, Tomiyasu T. Detailed investigation of methylmercury accumulation in rice grain from Hg 2+-spiked non-contaminated paddy field soils. CHEMOSPHERE 2020; 247:125827. [PMID: 31955040 DOI: 10.1016/j.chemosphere.2020.125827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/20/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Total-Hg (T-Hg) and methylmercury (MeHg) concentrations in rice grains were measured to understand the MeHg accumulation process. Rice plants were cultivated in Hg2+-spiked non-contaminated soils in experimental pots at three different places. Although soil MeHg concentrations in the pots changed significantly and individually during the rice-growing season, T-Hg concentration of brown rice grain was high at high soil MeHg concentration. In addition, there was no significant variation in T-Hg concentration in brown rice grains from individual panicles or among panicles obtained from the same pot, although the period of growth for each panicle was different. The highest T-Hg concentration of brown rice grains recorded for a panicle was 1.4 ± 0.1 mg kg-1 (n = 8), and the corresponding MeHg ratio was 76%. In addition, the T-Hg and MeHg concentrations in various parts of the brown rice grain-white rice (endosperm), bran, and embryo-were measured. Among the parts of the brown rice grain, the embryo had the highest Hg concentration. Furthermore, Hg concentration in the grain was constant during grain filling. These findings suggest that MeHg formed in soil accumulates in the rice plant during growth and is supplied to the rice grains continuously for the entire duration of the grain development period.
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Affiliation(s)
- Hitoshi Kodamatani
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065, Japan.
| | - Yuri Daiba
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065, Japan
| | - Shintarou Morisaki
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065, Japan
| | - Katsuyuki Ichitani
- Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan
| | - Ryo Kanzaki
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065, Japan
| | - Takashi Tomiyasu
- Division of Earth and Environmental Science, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, 890-0065, Japan
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30
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Tang WL, Liu YR, Guan WY, Zhong H, Qu XM, Zhang T. Understanding mercury methylation in the changing environment: Recent advances in assessing microbial methylators and mercury bioavailability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 714:136827. [PMID: 32018974 DOI: 10.1016/j.scitotenv.2020.136827] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/17/2020] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) is a neurotoxin, mainly derived from microbial mercury methylation in natural aquatic environments, and poses threats to human health. Polar regions and paddy soils are potential hotspots of mercury methylation and represent environmental settings that are susceptible to natural and anthropogenic perturbations. The effects of changing environmental conditions on the methylating microorganisms and mercury speciation due to global climate change and farming practices aimed for sustainable agriculture were discussed for polar regions and paddy soils, respectively. To better understand and predict microbial mercury methylation in the changing environment, we synthesized current understanding of how to effectively identify active mercury methylators and assess the bioavailability of different mercury species for methylation. The application of biomarkers based on the hgcAB genes have demonstrated the occurrence of potential mercury methylators, such as sulfate-reducing bacteria, iron-reducing bacteria, methanogen and syntrophs, in a diverse variety of microbial habitats. Advanced techniques, such as enriched stable isotope tracers, whole-cell biosensor and diffusive gradient thin film (DGT) have shown great promises in quantitatively assessing mercury availability to microbial methylators. Improved understanding of the complex structure of microbial communities consisting mercury methylators and non-methylators, chemical speciation of inorganic mercury under geochemically relevant conditions, and the pathway of cellular mercury uptake will undoubtedly facilitate accurate assessment and prediction of in situ microbial mercury methylation.
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Affiliation(s)
- Wen-Li Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Yu-Rong Liu
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Wen-Yu Guan
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario K9L 0G2, Canada
| | - Xiao-Min Qu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China.
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31
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Xiao A, Li WC, Ye Z. Effects of Fe-oxidizing bacteria (FeOB) on iron plaque formation, As concentrations and speciation in rice (Oryza sativa L.). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 190:110136. [PMID: 31901806 DOI: 10.1016/j.ecoenv.2019.110136] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/24/2019] [Accepted: 12/24/2019] [Indexed: 06/10/2023]
Abstract
Large areas of the paddy fields in South China are contaminated with arsenic (As), which causes serious problems, including high As concentrations in brown rice. Three As-resistant iron-oxidizing bacteria (FeOB) namely, Bacillus sp. T2, Pseudomonas sp. Yangling I4 and Bacillus sp. TF1-3, were isolated and applied to rice grown in different As-contaminated environments to study the effects of FeOB on the As accumulation in rice and clarify the possible mechanisms involved. The results showed that FeOB inoculation significantly decreased the inorganic As concentrations in brown rice grown in pots and paddy fields by 3.7-13.3% and 4.6-12.1%, respectively. FeOB inoculation enhanced the formation of Fe plaque, which sequestered more As on the root surface. Moreover, a significantly lower level of As(III) influx was observed in the rice cultivated with FeOB than in the control. FeOB inoculation also decreased the As concentrations in pore water and the Fe(II)/Fe(III) ratio in rhizosphere soil. The present results suggest that FeOB inoculation decreased the inorganic As concentrations in brown rice by affecting the formation of Fe plaque, As(III) uptake kinetics and rhizosphere soil properties. Based on our results, FeOB inoculation could be considered a useful method to decrease inorganic As concentrations in brown rice grown in As-contaminated paddy fields.
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Affiliation(s)
- Anwen Xiao
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Wai Chin Li
- Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, SAR, People's Republic of China.
| | - Zhihong Ye
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China.
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32
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Aw X, Z L, Wc L, Zh Y. The effect of plant growth-promoting rhizobacteria (PGPR) on arsenic accumulation and the growth of rice plants (Oryza sativa L.). CHEMOSPHERE 2020; 242:125136. [PMID: 31654806 DOI: 10.1016/j.chemosphere.2019.125136] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Large areas of paddy fields in southern China have been contaminated by arsenic (As), which causes serious problems such as the reduction of grain yield and high As concentrations in brown rice. To test the possibility of using plant growth-promoting rhizobacteria (PGPR) to promote rice growth and decrease As accumulation in brown rice in such paddy fields, three As-resistant PGPRs (strains S6, S7 and S10) were isolated and incorporated into two rice cultivars (Zhendao 14 and Jianyou G2) grown in different environments. The results showed that all PGPRs promoted rice growth (grain yield increased by 10.50-51.30% under greenhouse conditions and by 4.83-9.16% in paddy fields) and reduced As damage in rice. Specifically, S10 decreased As accumulation in brown rice in both greenhouse (3.50-26.01%) and paddy-field conditions (9.26-10.50%) by significantly reducing the available As concentration in rhizospheric soil, especially in the Dabaoshan-B field (34.00%). Conversely, in greenhouse condition, strains S6 and S7 increased As concentrations by 6.10-20.10% and 2.14-14.60%, respectively. Our results suggested that PGPR inoculation could be used to decrease As accumulation and promote rice growth in As-contaminated paddy fields. However, as the effects of PGPRs differed by strain and depended on environmental factors, careful selection of the strains and environmental conditions, and pre-testing, will be essential before applying PGPRs to As-contaminated paddy fields.
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Affiliation(s)
- Xiao Aw
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Li Z
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Li Wc
- Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, SAR, People's Republic of China.
| | - Ye Zh
- School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China.
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Khanam R, Kumar A, Nayak AK, Shahid M, Tripathi R, Vijayakumar S, Bhaduri D, Kumar U, Mohanty S, Panneerselvam P, Chatterjee D, Satapathy BS, Pathak H. Metal(loid)s (As, Hg, Se, Pb and Cd) in paddy soil: Bioavailability and potential risk to human health. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 699:134330. [PMID: 31522043 DOI: 10.1016/j.scitotenv.2019.134330] [Citation(s) in RCA: 145] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/03/2019] [Accepted: 09/05/2019] [Indexed: 05/04/2023]
Abstract
Rice is one of the principal staple foods, essential for safeguarding the global food and nutritional security, but due to different natural and anthropogenic sources, it also acts as one of the biggest reservoirs of potentially toxic metal(loids) like As, Hg, Se, Pb and Cd. This review summarizes mobilization, translocation and speciation mechanism of these metal(loids) in soil-plant continuum as well as available cost-effective remediation measures and future research needs to eliminate the long-term risk to human health. High concentrations of these elements not only cause toxicity problems in plants, but also in animals that consume them and gradual deposition of these elements leads to the risk of bioaccumulation. The extensive occurrence of contaminated rice grains globally poses substantial public health risk and merits immediate action. People living in hotspots of contamination are exposed to higher health risks, however, rice import/export among different countries make the problem of global concern. Accumulation of As, Hg, Se, Pb and Cd in rice grains can be reduced by reducing their bioavailability, and controlling their uptake by rice plants. The contaminated soils can be reclaimed by phytoremediation, bioremediation, chemical amendments and mechanical measures; however these methods are either too expensive and/or too slow. Integration of innovative agronomic practices like crop establishment methods and improved irrigation and nutrient management practices are important steps to help mitigate the accumulation in soil as well as plant parts. Adoption of transgenic techniques for development of rice cultivars with low accumulation in edible plant parts could be a realistic option that would permit rice cultivation in soils with high bioavailability of these metal(loid)s.
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Affiliation(s)
- Rubina Khanam
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - Anjani Kumar
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - A K Nayak
- ICAR - National Rice Research Institute, Cuttack, Odisha, India.
| | - Md Shahid
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - Rahul Tripathi
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - S Vijayakumar
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | | | - Upendra Kumar
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - Sangita Mohanty
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - P Panneerselvam
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | | | - B S Satapathy
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
| | - H Pathak
- ICAR - National Rice Research Institute, Cuttack, Odisha, India
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Xu X, Han J, Abeysinghe KS, Atapattu AJ, De Silva PMCS, Xu Z, Long S, Qiu G. Dietary exposure assessment of total mercury and methylmercury in commercial rice in Sri Lanka. CHEMOSPHERE 2020; 239:124749. [PMID: 31505443 DOI: 10.1016/j.chemosphere.2019.124749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Revised: 08/28/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) in rice has attracted growing health concern over the past decade, due to the accumulation of high MeHg levels, which may pose potential health risk to humans. Rice is the staple food in Sri Lanka; nevertheless, the presence of micro pollutants, such as MeHg has been not investigated. Therefore, commercial rice samples from the Sri Lankan market (n = 163) were measured to reveal the total mercury (THg) and MeHg levels. THg (mean: 1.73 ± 0.89 ng/g, range: 0.21-6.13 ng/g) and MeHg concentrations (mean: 0.51 ± 0.37 ng/g; range: 0.03-3.81 ng/g) were low. Compared to the fish MeHg exposure, the rice MeHg exposure was generally lower in different consumption groups, suggesting that rice plays a less role than fish in MeHg exposure in Sri Lanka. Babies (infants and toddlers) at one year old may face fish MeHg exposure (0.17 μg/kg bw/day) higher than the reference dose for MeHg (RfD)-0.1 μg/kg bw/day, which was more than 5 times that of rice MeHg exposure (0.031 μg/kg bw/day). Future studies in Sri Lanka should focus on health impacts under long-term overexposure of MeHg, especially in vulnerable populations. Some diet changes should be made to mitigate MeHg exposure levels in Sri Lankans.
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Affiliation(s)
- Xiaohang Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jialiang Han
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kasun S Abeysinghe
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Anjana J Atapattu
- University of Chinese Academy of Sciences, Beijing, 100049, China; Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China; Agronomy Division, Coconut Research Institute, Lunuwila, 61150, Sri Lanka
| | | | - Zhidong Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | | | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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Wang Y, Chen Z, Wu Y, Zhong H. Comparison of methylmercury accumulation in wheat and rice grown in straw-amended paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 697:134143. [PMID: 31476499 DOI: 10.1016/j.scitotenv.2019.134143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/16/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Paddy soil is a key area of methylmercury (MeHg) production and is dominated by fluctuating redox conditions following rice plant growth or rice-wheat rotation planting in eastern and southern Asia. The role of organic matter in the formation of MeHg under these biogeochemical redox cycles remains poorly understood, especially in certain mercury (Hg)-contaminated paddy soils. Here, we provide a detailed understanding of the formation of MeHg and its accumulation in crops (i.e., wheat and rice) in rice-wheat rotation systems under straw return. Two series of experiments, pot and microcosm experiments, were performed using Hg-contaminated paddy soil with 1% (w/w) wheat or rice straw addition under aerobic or anoxic conditions. The results showed that straw amendments increased MeHg levels in wheat (by 225%) and rice (by 20%) grains, most likely due to the elevated soil MeHg following straw amendment. Microcosm experiments further confirmed that fresh straw-derived organic matter enhances MeHg net production in soil through an overall increase in the activity of sulfate-reducing bacteria (SRB), particularly under anoxic conditions. Our study clearly demonstrated that straw amendment enhanced MeHg accumulation in wheat and rice grains and highlighted that straw return in Hg-contaminated soils may increase the health risk of MeHg exposure to local residents via crop consumption. Thus, some guidance should be provided for crop residue return in rice-wheat rotation system farming practices.
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Affiliation(s)
- Yongjie Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China
| | - Zongya Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Yonggui Wu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang 550002, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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Gygax S, Gfeller L, Wilcke W, Mestrot A. Emerging investigator series: mercury mobility and methylmercury formation in a contaminated agricultural flood plain: influence of flooding and manure addition. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:2008-2019. [PMID: 31617529 DOI: 10.1039/c9em00257j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The fate and the methylation of mercury (Hg) in the terrestrial environment are still poorly understood and although the main drivers of release and methylation of mercury in soils are known (low redox potential and microbial carbon availability) their interactions are not well understood. This is of concern since many agriculturally used floodplains, where the recurring flooding and agricultural practices (e.g. manure amendments) may have an impact on the fate and the biomethylation of Hg, are at the same time Hg-contaminated. In this study, we modified and validated existing methods to extract and analyze methylmercury (MeHg) by HPLC-ICP-MS in soils and we assessed the Hg and MeHg concentrations in three fields situated in a Hg polluted agricultural floodplain. Further, we incubated the top soil from the three studied fields for 11 days under flooded conditions in presence or absence of 2 mass% of cow manure, a common agricultural amendment in the area. Total Hg and MeHg concentrations ranged from <limit of detection (LOD, 0.012 mg kg-1) to 28.2 mg kg-1 and from 1.2 to 7.8 μg kg-1 respectively. Hg was released to the soil solution after 12 hours with a maximum between day 2 and day 7. MeHg levels in the soil solution were <LOD although it was found in the soil before and after the incubation. The addition of cow manure to saturated soils led to an increase in the MeHg concentrations of the soil solid phase by up to fivefold to a maximum of 26.4 ± 1.1 μg kg-1 (n = 3). Our study demonstrates that the combination of low redox potential because of flooding with common agricultural practices such as the amendment of manures enhances the formation of toxic MeHg.
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Affiliation(s)
- Sebastian Gygax
- Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland
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Li Y, Wang Y, Zhang Q, Hu W, Zhao J, Chen Y, Zhong H, Wang G, Zhang Z, Gao Y. Elemental sulfur amendment enhance methylmercury accumulation in rice (Oryza sativa L.) grown in Hg mining polluted soil. JOURNAL OF HAZARDOUS MATERIALS 2019; 379:120701. [PMID: 31299630 DOI: 10.1016/j.jhazmat.2019.05.094] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 05/14/2019] [Accepted: 05/28/2019] [Indexed: 06/10/2023]
Abstract
The influence of elemental sulfur (S(0)) amendment on methylmercury (MeHg) accumulation in rice and the chemical form of Hg in the rhizosphere were investigated under waterlogged conditions in Hg-contaminated soil (the majority of the Hg (˜70%) in forms similar to HgS). Different levels of S(0) addition increased the MeHg accumulation in rice. After a sequential extraction analysis of the chemical forms of Hg in the rhizosphere, the results showed that S(0) addition increased the organic bound Hg and decreased the residual Hg in the soils. An Hg LIII XANES further showed that S(0) addition increased the proportion of Hg in the form of RS-Hg-SR and decreased the proportion of Hg in the form of HgS, indicating that S(0) input may reactivate the non-bioavailable Hg in the rhizosphere and improve the net Hg methylation. These findings suggest that the application of S fertilizers to Hg-contaminated paddy soils may increase the MeHg concentration in the edible parts of crops, which may lead to more potential health problems in humans depending on the crop type. However, our study also suggests that S(0) addition could be an effective measure for mobilizing the insoluble Hg and accelerating the phytoremediation process in Hg-contaminated paddy soils.
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Affiliation(s)
- Yunyun Li
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China; CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yongjie Wang
- School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Qijia Zhang
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Wenjun Hu
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yanhui Chen
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Guo Wang
- College of Resources and Environment, Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China
| | - Zhiyong Zhang
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, and HKU-IHEP Joint Laboratory on Metallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
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38
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Du S, Wang X, Zhang T, Ding C. Kinetic characteristics and predictive models of methylmercury production in paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 253:424-428. [PMID: 31325887 DOI: 10.1016/j.envpol.2019.07.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 06/25/2019] [Accepted: 07/10/2019] [Indexed: 06/10/2023]
Abstract
Understanding the mercury (Hg) methylation process is important for the management of paddy soils contaminated by Hg. In this work, samples of eighteen paddy soils with varying soil properties were spiked with inorganic Hg and subjected to a 90 d flooding period. Soil pH and redox potential (Eh) were measured in situ at intervals, and soils were sampled for the analysis of methylmercury (MeHg). The Hg methylation efficiency increased with flooding time and reached a relatively steady state at 30 d of incubation, ranging from 0.08% to 2.52%, and was significantly correlated with the in situ soil pH and Eh. The Elovich equation could adequately describe the kinetic production of MeHg. MeHg production was well predicted by the in situ soil pH and Eh of flooded soils, in addition to the organic matter content of air-dried soil samples and flooding time. The two predictive models explained 78% and 68% of the variability of the Hg methylation efficiency. The results suggested that the methylation of inorganic Hg in paddy soils after flooding can be predicted as a function of routinely measured soil properties and flooding time, a correlation that can be utilized to improve understanding of the extent of Hg methylation and the management of Hg-contaminated paddy soils.
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Affiliation(s)
- Shuyang Du
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xingxiang Wang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Ecological Experimental Station of Red Soil, Chinese Academy of Sciences, Yingtan 335211, China
| | - Taolin Zhang
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Changfeng Ding
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
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Wang X, Ma X, Wen J, Geng Z, Wang Z. A novel bimacrocyclic polyamine-based fluorescent probe for sensitive detection of Hg 2+ and glutathione in human serum. Talanta 2019; 207:120311. [PMID: 31594615 DOI: 10.1016/j.talanta.2019.120311] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/24/2019] [Accepted: 09/02/2019] [Indexed: 12/16/2022]
Abstract
Detection of glutathione in human serum is of great importance for clinical diagnosis of various diseases, such as AIDS, diabetes mellitus, Alzheimer disease and cancer. In this work, a new water-soluble bismacrocyclic polyamine-derived compound, namely L, which contains two molecules of 4-nitro-1,2,3-benzoxa-diazole as the fluorophores, was designed and prepared. The experiments of selectivity of L toward metal ions showed it could rapidly and sensitively detect Hg2+ with a detection limit of 27 nM. Furthermore, the cell imaging and co-staining experiments in HeLa cells demonstrated that the L-Hg2+ probe had selectivity for the Golgi apparatus to a certain degree. Moreover, it had excellent selectivity for biothiols, especially for glutathione. Finally, the probe was successfully applied to sensitively detect glutathione (GSH) in human serum and fetal bovine serum.
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Affiliation(s)
- Xiaobo Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, PR China; Pharmacy School, Hubei University of Science and Technology, Xianning, 437100, PR China
| | - Xiaoyan Ma
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, PR China
| | - Jinghan Wen
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, PR China
| | - Zhirong Geng
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, PR China.
| | - Zhilin Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210023, PR China.
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40
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Tang W, Hintelmann H, Gu B, Feng X, Liu Y, Gao Y, Zhao J, Zhu H, Lei P, Zhong H. Increased Methylmercury Accumulation in Rice after Straw Amendment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6144-6153. [PMID: 30983351 DOI: 10.1021/acs.est.8b07145] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Consumption of rice has been shown to be an important route of dietary exposure to methylmercury (MeHg, a neurotoxin) for Asians having a low fish but high rice diet. Therefore, factors that increase MeHg production and bioaccumulation in soil-rice systems, could enhance the risk of MeHg exposure. On the basis of a national-scale survey in China (64 sites in 12 provinces) and rice cultivation experiments, we report that straw amendment, a globally prevalent farming practice, could increase MeHg concentrations in paddy soils (11-1043%) and rice grains (95%). By carrying out a series of batch incubation, seedling uptake and sand culture experiments, we demonstrate that these increases could be attributed to (1) enhanced abundances/activities of microbial methylators and the transformation of refractory HgS to organic matter-complexed Hg, facilitating microbial Hg methylation in soils; (2) enhanced MeHg mobility, and increased root lengths (35-41%) and tip numbers (60-105%), increasing MeHg uptake by rice roots; and (3) enhanced MeHg translocation to rice grains from other tissues. Results of this study emphasize fresh organic matter-enhanced MeHg production and bioaccumulation, and highlight the increased risk of MeHg after straw amendment and thus the need for new policies concerning straw management.
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Affiliation(s)
- Wenli Tang
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
| | - Holger Hintelmann
- Department of Chemistry , Trent University , Peterborough , Ontario K9L 0G2 , Canada
| | - Baohua Gu
- Environmental Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry , Institute of Geochemistry, Chinese Academy of Sciences , Guiyang , Guizhou Province 550081 , P. R. China
| | - Yurong Liu
- College of Resources and Environment , Huazhong Agricultural University , Wuhan , Hubei Province 430070 , P. R. China
| | - Yuxi Gao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, and Laboratory of Metallomics and Nanometallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Jiating Zhao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, and Laboratory of Metallomics and Nanometallomics , Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049 , P. R. China
| | - Huike Zhu
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
| | - Pei Lei
- Institute for Advanced Study , Shenzhen University , Shenzhen , Guangdong Province 518060 , P. R. China
| | - Huan Zhong
- School of the Environment , Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse , Nanjing , Jiangsu Province 210023 , P. R. China
- Environmental and Life Sciences Program (EnLS) , Trent University , Peterborough , Ontario K9L 0G2 , Canada
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Salam A, Shaheen SM, Bashir S, Khan I, Wang J, Rinklebe J, Rehman FU, Hu H. Rice straw- and rapeseed residue-derived biochars affect the geochemical fractions and phytoavailability of Cu and Pb to maize in a contaminated soil under different moisture content. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 237:5-14. [PMID: 30776771 DOI: 10.1016/j.jenvman.2019.02.047] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/19/2019] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
Abstract
Management of toxic elements contaminated upland and wetland soils using biochar is of great concern from both agricultural and environmental points of view. The impact of rice straw- and rapeseed residue-derived biochars produced under 300 °C and 550 °C (added to the soil at 2% and 5%; w/w) on the geochemical fractions, phytoavailability, and uptake of Cu and Pb in a contaminated mining soil under different moisture contents (80%, 60%, and 40% of soil field capacity) was investigated in a greenhouse pot experiment using maize. The higher rate of rice straw-derived biochar pyrolyzed at 550 °C caused a significant reduction in the mobile (soluble + exchangeable) fraction of Cu (59.42%) and Pb (75.4%) and increased the residual fractions of Cu (37.8%) and Pb (54.7%) in the treated soil under the highest moisture content (80%) as compared to the untreated soil. Therefore, this biochar significantly decreased the phytoavailability (CaCl2-extractable form) of Cu by 59.5% and Pb by 67.6% under the highest moisture content. Also, at the same moisture level (80%), the higher rate of rapeseed residue-derived biochar pyrolyzed at 550 °C decreased significantly the phytoavailability of Cu by 46.5% and Pb by 60.52% as compared to the untreated soil. The 5% rate of the higher temperature pyrolyzed rice straw and rapeseed biochars decreased the uptake of Cu and Pb by the roots and shoots of maize up to 51% for Cu and 45% for Pb. Immobilization of Cu and Pb in the biochar-treated soil at 80% moisture content may possibly due to the associated increase of soil pH and poorly-crystalline Fe oxides content, and/or the metals precipitation with sulfides. These results indicated that application of high temperature pyrolyzed rice straw- and rapeseed residue-derived biochars at 5% could immobilize Cu and Pb and decrease their uptake by maize under high levels of moisture content; consequently, they can be used for phyto-management of Cu and Pb contaminated wetland soils.
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Affiliation(s)
- Abdus Salam
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, No. 1 Shizishan Street, Hongshan District, Wuhan, Hubei, 430070, PR China.
| | - Sabry M Shaheen
- University of Kafrelsheikh, Faculty of Agriculture, Department of Soil and Water Sciences, 33 516, Kafr El-Sheikh, Egypt; University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285, Wuppertal, Germany; King Abdulaziz University, Faculty of Meteorology, Environment, and Arid Land Agriculture, Department of Arid Land Agriculture, Jeddah, 21589, Saudi Arabia.
| | - Saqib Bashir
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, No. 1 Shizishan Street, Hongshan District, Wuhan, Hubei, 430070, PR China; Department of Soil and Environmental Science, Ghazi University Dera Ghazi Khan, Pakistan.
| | - Imran Khan
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, No. 1 Shizishan Street, Hongshan District, Wuhan, Hubei, 430070, PR China.
| | - Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550002, Guiyang, PR China.
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285, Wuppertal, Germany; Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Seoul, Republic of Korea.
| | - Fazal Ur Rehman
- College of Resource and Environmental Sciences, China Agricultural University, Haidian District, Beijing, 100193, PR China.
| | - Hongqing Hu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, No. 1 Shizishan Street, Hongshan District, Wuhan, Hubei, 430070, PR China.
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Tang W, Su Y, Gao Y, Zhong H. Effects of Farming Activities on the Biogeochemistry of Mercury in Rice-Paddy Soil Systems. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:635-642. [PMID: 31053868 DOI: 10.1007/s00128-019-02627-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
The biogeochemistry of mercury (Hg) in rice-paddy soil systems raises concerns, given that (1) the redox potential in paddy soil favors Hg methylation and (2) rice plants have a strong ability to accumulate methylmercury (MeHg), making rice an important source for MeHg exposure to humans. Therefore, all factors affecting the behavior of Hg in rice-paddy soils might impact Hg accumulation in rice, with its subsequent potential risks. As a typical wetland, paddy soils are managed by humans and affected by anthropogenic activities, such as agronomic measures, which would impact soil properties and thus Hg biogeochemistry. In this paper, we reviewed recent advances in the effects of farming activities including water management, fertilizer application and rotation on Hg biogeochemistry, trying to elucidate the factors controlling Hg behavior and thus the ecological risks in rice-paddy soil systems. This review might provide new thoughts on Hg remediation and suggest avenues for further studies.
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Affiliation(s)
- Wenli Tang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yao Su
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China
| | - Yuxi Gao
- State Environmental Protection Engineering Center for Mercury Pollution Prevention and Control, Laboratory of Metallomics and Nanometallomics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, China.
- Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, ON, Canada.
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Wang M, Tang Z, Chen XP, Wang X, Zhou WX, Tang Z, Zhang J, Zhao FJ. Water management impacts the soil microbial communities and total arsenic and methylated arsenicals in rice grains. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 247:736-744. [PMID: 30721864 DOI: 10.1016/j.envpol.2019.01.043] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/17/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
The bioavailability of the metalloid arsenic (As) in paddy soil is controlled by microbial cycling of As and other elements such as iron (Fe) and sulfur (S), which are strongly influenced by water management in paddy fields. In this study, we evaluated how water management affects As bioavailability by growing rice plants in a geogenic As-contaminated soil. We determined As speciation in soil porewater and the diversity of the associated microbial community. Continuous flooding enhanced the release of Fe and As and increased arsenite (As(III)) and methylated As species concentrations in the rice grain compared with aerobic treatment. Total inorganic and organic As in the grain was 84% and 81% lower, respectively, in the aerobic treatment compared with the continuous flooding treatment. The amounts of Fe(III)-reducing bacteria (FeRB) increased in the flooded rhizosphere soil. The abundance of FeRB in the soil correlated with the dissolution of Fe and As. Among the As-transformation genes quantified, the aioA gene for As(III) oxidation and arsM gene for As(III) methylation were most abundant. The arsM copy number correlated positively with the levels of dsrB (dissimilatory (bi) sulfite reductase β-subunit), suggesting that dissimilatory sulfate-reducing bacteria (SRB) may play an important role in dimethylarsenate (DMAs(V)) production in soil. Our results show that decreased populations of rhizosphere FeRB and SRB contributed to a lower bioavailability of As, and decreased production of methylated arsenicals under oxic conditions.
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Affiliation(s)
- Ming Wang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhong Tang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xue-Ping Chen
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Xin Wang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Wu-Xian Zhou
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Institute of Chinese Herbal Medicine, Hubei Academy of Agricultural Sciences, Enshi, 445000, China
| | - Zhu Tang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jun Zhang
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Fang-Jie Zhao
- Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China
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Wang Y, Dang F, Zheng X, Zhong H. Biochar amendment to further reduce methylmercury accumulation in rice grown in selenium-amended paddy soil. JOURNAL OF HAZARDOUS MATERIALS 2019; 365:590-596. [PMID: 30471573 DOI: 10.1016/j.jhazmat.2018.11.052] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/19/2018] [Accepted: 11/13/2018] [Indexed: 06/09/2023]
Abstract
Methylmercury (MeHg) accumulation in rice is an emerging food safety issue in China and other countries; however, mitigation methods are scarce. Here, the effects of selenium (Se) and multiple applications of Se and biochar on rice MeHg bioaccumulation were investigated using pot and microcosm experiments. We report that Se amendment was still effective in reducing MeHg levels in paddy soil and rice grain after three years of aging. Biochar amendment (0.5% w/w) further decreased grain (brown rice) MeHg levels by 82-87%. The grain MeHg level decrease following the combination of Se and biochar amendment could be partly attributed to inhibition of net MeHg production in soil by Se. In addition, biochar decreased not only net MeHg production but also MeHg bioavailability in the soil, which could be due to organosulfur compounds in the biochar. Our findings suggest that multiple applications of Se and biochar could be a novel remediation strategy to mitigate MeHg accumulation in rice.
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Affiliation(s)
- Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Fei Dang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, PR China
| | - Xiangmin Zheng
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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45
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Qin C, Chen M, Yan H, Shang L, Yao H, Li P, Feng X. Compound specific stable isotope determination of methylmercury in contaminated soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 644:406-412. [PMID: 29981990 DOI: 10.1016/j.scitotenv.2018.06.328] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/24/2018] [Accepted: 06/26/2018] [Indexed: 06/08/2023]
Abstract
Rice is one of the main sources of methylmercury (MeHg) to humans, and soil is the main source of MeHg to rice grains. Determining the Hg isotope composition in environmental samples is a good way of characterizing sources of Hg pollution and investigating environmental processes. We developed a new compound-specific method for determining stable Hg isotopes in MeHg in contaminated soil and sediment. The method involved HNO3 leaching/solvent extraction, chemical ethylation, and separation by gas chromatography with a solenoid valve optimized to enrich MeHg. The method was optimized by using MeHg standard solution, certified reference materials and paddy soil samples. The δ202Hg precision for replicate MeHg isotope analyses was 0.14‰ (2 × standard deviation, n = 11), and no fractionation of Hg stable isotopes was found during the separation processes. The δ202Hg values for MeHg in paddy soils were -1.78‰ to -1.30‰, which were lower than the δ202Hg values for total Hg (-1.32‰ to -0.44‰). The results indicated that methylation (rather than demethylation) was the dominant process in the paddy soils. The method developed in this study can help us to better understand MeHg migration and transformation processes in paddy soil-rice ecosystem.
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Affiliation(s)
- Chongyang Qin
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Chen
- School of Public Health, Guizhou Medical University, Guiyang 550025, China
| | - Haiyu Yan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Lihai Shang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Heng Yao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
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46
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Zhao JY, Ye ZH, Zhong H. Rice root exudates affect microbial methylmercury production in paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 242:1921-1929. [PMID: 30072222 DOI: 10.1016/j.envpol.2018.07.072] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/16/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
Microbial methylmercury (MeHg) production in contaminated soil-rice systems and its accumulation in rice pose health risks to consumers, especially those in Asia. However, the mechanism responsible for microbial MeHg production in paddy soils is far from clear. While previous studies examined the effect of soil and microbial factors on soil MeHg levels, in this work we explored the impact of rice cultivation itself on microbial MeHg production, focusing on the root exudate organic matter as a potential source of electron donors for microbial methylators. Effects of the cultivation of two rice cultivars, Heigu246 (H-rice) and Neiwuyou8015 (N-rice), on MeHg production in soils were therefore investigated in pot and batch incubation experiments. Soil MeHg levels measured in H-rice treatment during the heading and harvest stages were 18-49% higher than in the control and 23-108% higher than in N-rice treatment. Consequently, MeHg levels in grain, straw, and root were 38%, 81%, and 40% higher in H-rice than those in N-rice, which was mainly attributed to cultivar-specific MeHg production in soils. Results of the batch experiments suggested that root exudate organic matter could be responsible for MeHg production in soils during rice cultivation, by increasing the abundances of potential microbial methylators. For instance, root exudate organic matter increased copy numbers of Hg methylation genes (hgcA) in soils 4.1-fold. Furthermore, the 211% higher concentration of acetate (a key electron donor for microbial methylators) in the root exudate of H-rice could account for the higher MeHg production under H-rice than N-rice cultivation. Our results suggest that root exudate organic matter, especially acetate, as its key component, contributes to the elevated soil MeHg concentrations during rice cultivation. The proposed mechanism provides new insights into the elevated risk of MeHg production in contaminated soil-rice systems, as well as cultivar-specific MeHg bioaccumulation.
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Affiliation(s)
- Jia-Yin Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Zhi-Hong Ye
- State Key Laboratory for Bio-control and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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47
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Tang R, Ding C, Dang F, Ma Y, Wang J, Zhang T, Wang X. NMR-based metabolic toxicity of low-level Hg exposure to earthworms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 239:428-437. [PMID: 29679940 DOI: 10.1016/j.envpol.2018.04.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 06/08/2023]
Abstract
Mercury is a globally distributed toxicant to aquatic animals and mammals. However, the potential risks of environmental relevant mercury in terrestrial systems remain largely unclear. The metabolic profiles of the earthworm Eisenia fetida after exposure to soil contaminated with mercury at 0.77 ± 0.09 mg/kg for 2 weeks were investigated using a two-dimensional nuclear magnetic resonance-based (1H-13C NMR) metabolomics approach. The results revealed that traditional endpoints (e.g., mortality and weight loss) did not differ significantly after exposure. Although histological examination showed sub-lethal toxicity in the intestine as a result of soil ingestion, the underlying mechanisms were unclear. Metabolite profiles revealed significant decreases in glutamine and 2-hexyl-5-ethyl-3-furansulfonate in the exposed group and remarkable increases in glycine, alanine, glutamate, scyllo-inositol, t-methylhistidine and myo-inositol. More importantly, metabolic network analysis revealed that low mercury in the soil disrupted osmoregulation, amino acid and energy metabolisms in earthworms. A metabolic net link and schematic diagram of mercury-induced responses were proposed to predict earthworm responses after exposure to mercury at environmental relevant concentrations. These results improved the current understanding of the potential toxicity of low mercury in terrestrial systems.
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Affiliation(s)
- Ronggui Tang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China; University of the Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Changfeng Ding
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China
| | - Fei Dang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China
| | - Yibing Ma
- Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Junsong Wang
- Center for Molecular Metabolism, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210014, People's Republic of China
| | - Taolin Zhang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China
| | - Xingxiang Wang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
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Yin D, He T, Yin R, Zeng L. Effects of soil properties on production and bioaccumulation of methylmercury in rice paddies at a mercury mining area, China. J Environ Sci (China) 2018; 68:194-205. [PMID: 29908739 DOI: 10.1016/j.jes.2018.04.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 04/30/2018] [Accepted: 04/30/2018] [Indexed: 06/08/2023]
Abstract
Rice paddy soil is recognized as the hotspot of mercury (Hg) methylation, which is mainly a biotic process mediated by many abiotic factors. In this study, effects of key soil properties on the production and bioaccumulation of Hg and methylmercury (MeHg) in Hg-contaminated rice paddies were investigated. Rice and soil samples were collected from the active Hg smelting site and abandoned Hg mining sites (a total of 124 paddy fields) in the Wanshan Mercury Mine, China. Total Hg (THg) and MeHg in soils and rice grains, together with sulfur (S), selenium (Se), organic matter (OM), nitrogen (N), phosphorus (P), mineral compositions (e.g., SiO2, Al2O3 and Fe2O3) and pH in soils were quantified. The results showed that long-term Hg mining activities had resulted in THg and MeHg contaminations in soil-rice system. The newly-deposited atmospheric Hg was more readily methylated relative to the native Hg already in soils, which could be responsible for the elevated MeHg levels in soils and rice grains around the active artificial Hg smelting site. The MeHg concentrations in soils and rice grains showed a significantly negative relationship with soil N/Hg, S/Hg and OM/Hg ratio possibly due to the formation of low-bioavailability Hg-S(N)-OM complexes in rhizosphere. The Hg-Se antagonism undoubtedly occurred in soil-rice system, while its role in bioaccumulation of MeHg in the MeHg-contaminated rice paddies was minor. However, other soil properties showed less influence on the production and bioaccumulation of MeHg in rice paddies located at the Wanshan Mercury Mine zone.
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Affiliation(s)
- Deliang Yin
- The Key Laboratory of Karst Environment and Geohazard Prevention, Guizhou University, Guiyang 550003, China; College of Resources and Environments, Southwest University, Chongqing 400715, China
| | - Tianrong He
- The Key Laboratory of Karst Environment and Geohazard Prevention, Guizhou University, Guiyang 550003, China.
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China; Department of Civil and Environmental Engineering, Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Lingxia Zeng
- The Key Laboratory of Karst Environment and Geohazard Prevention, Guizhou University, Guiyang 550003, China
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Jia Q, Zhu X, Hao Y, Yang Z, Wang Q, Fu H, Yu H. Mercury in soil, vegetable and human hair in a typical mining area in China: Implication for human exposure. J Environ Sci (China) 2018; 68:73-82. [PMID: 29908747 DOI: 10.1016/j.jes.2017.05.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/09/2017] [Accepted: 05/12/2017] [Indexed: 06/08/2023]
Abstract
Concentrations of total mercury (T-Hg) and methylmercury (MeHg) in soil, vegetables, and human hair were measured in a mercury mining area in central China. T-Hg and MeHg concentrations in soil ranged from 1.53 to 1054.97mg/kg and 0.88 to 46.52μg/kg, respectively. T-Hg concentrations was correlated with total organic carbon (TOC) content (R2=0.50, p<0.01) and pH values (R2=0.21, p<0.05). A significant linear relationship was observed between MeHg concentrations and the abundance of sulfate-reducing bacteria (SRB) (R2=0.39, p<0.05) in soil. Soil incubation experiments amended with specific microbial stimulants and inhibitors showed that Hg methylation was derived from SRB activity. T-Hg and MeHg concentrations in vegetables were 24.79-781.02μg/kg and 0.01-0.18μg/kg, respectively; levels in the edible parts were significantly higher than in the roots (T-Hg: p<0.05; MeHg: p<0.01). Hg species concentrations in rhizosphere soil were positively correlated to those in vegetables (p<0.01), indicating that soil was an important source of Hg in vegetables. Risk assessment indicated that the consumption of vegetables could result in higher probable daily intake (PDI) of T-Hg than the provisional tolerable daily intake (PTDI) for both adults and children. In contrast, the PDI of MeHg was lower than the reference dose. T-Hg and MeHg concentrations in hair samples ranged from 1.57 to 12.61mg/kg and 0.04 to 0.94mg/kg, respectively, and MeHg concentration in hair positively related to PDI of MeHg via vegetable consumption (R2=0.39, p<0.05), suggesting that vegetable may pose health risk to local residents.
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Affiliation(s)
- Qin Jia
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Xuemei Zhu
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Yaqiong Hao
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Ziliang Yang
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Qi Wang
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Haihui Fu
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hongjin Yu
- Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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50
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Tang Z, Fan F, Wang X, Shi X, Deng S, Wang D. Mercury in rice (Oryza sativa L.) and rice-paddy soils under long-term fertilizer and organic amendment. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 150:116-122. [PMID: 29272715 DOI: 10.1016/j.ecoenv.2017.12.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 11/30/2017] [Accepted: 12/09/2017] [Indexed: 06/07/2023]
Abstract
High levels of mercury (Hg), especially methylmercury (MeHg), in rice is of concern due to its potential of entering food chain and the high toxicity to human. The level and form of Hg in rice could be influenced by fertilizers and other soil amendments. Studies were conducted to evaluate the effect of 24 years application of chemical fertilizers and organic amendments on total Hg (THg) and MeHg and their translocation in soil, plants, and rice grain. All treatments led to significantly higher concentrations of MeHg in grain than those from the untreated control. Of nine treatments tested, chemical fertilizers combining with returning rice straw (NPK1+S) led to highest MeHg concentration in grain and soil; while the nitrogen and potassium (NK) treatment led to significantly higher THg in grain. Concentrations of soil MeHg were significantly correlated with THg in soil (r = 0.59***) and MeHg in grain (r = 0.48***). Calcium superphosphate negatively affected plant bioavailability of soil Hg. MeHg concentration in rice was heavily influenced by soil Hg levels. Phosphorus fertilizer was a main source contributing to soil THg, while returning rice straw to the field contributed significantly to MeHg in soil and rice grain. As a result, caution should be exercised in soil treatment or when utilizing Hg-contaminated soils to produce rice for human consumption. Strategic management of rice straw and phosphorus fertilizer could be effective strategies of lowering soil Hg, which would ultimately lower MeHg in rice and the risk of Hg entering food chain.
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Affiliation(s)
- Zhenya Tang
- College of Resources and Environment, Southwest University, China; Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Fangling Fan
- College of Resources and Environment, Southwest University, China; Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Xinyue Wang
- College of Resources and Environment, Southwest University, China
| | - Xiaojun Shi
- College of Resources and Environment, Southwest University, China; The National Long- Term Fertilizer Experimental Station in Purple Soil, Southwest University, China
| | - Shiping Deng
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing, China.
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