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Boie F, Ducey TF, Xing Y, Wang J, Rinklebe J. Field-aged rice hull biochar stimulated the methylation of mercury and altered the microbial community in a paddy soil under controlled redox condition changes. JOURNAL OF HAZARDOUS MATERIALS 2024; 472:134446. [PMID: 38696958 DOI: 10.1016/j.jhazmat.2024.134446] [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: 02/05/2024] [Revised: 03/25/2024] [Accepted: 04/25/2024] [Indexed: 05/04/2024]
Abstract
Mercury (Hg) contaminated paddy soils are hot spots for methylmercury (MeHg) which can enter the food chain via rice plants causing high risks for human health. Biochar can immobilize Hg and reduce plant uptake of MeHg. However, the effects of biochar on the microbial community and Hg (de)methylation under dynamic redox conditions in paddy soils are unclear. Therefore, we determined the microbial community in an Hg contaminated paddy soil non-treated and treated with rice hull biochar under controlled redox conditions (< 0 mV to 600 mV) using a biogeochemical microcosm system. Hg methylation exceeded demethylation in the biochar-treated soil. The aromatic hydrocarbon degraders Phenylobacterium and Novosphingobium provided electron donors stimulating Hg methylation. MeHg demethylation exceeded methylation in the non-treated soil and was associated with lower available organic matter. Actinobacteria were involved in MeHg demethylation and interlinked with nitrifying bacteria and nitrogen-fixing genus Hyphomicrobium. Microbial assemblages seem more important than single species in Hg transformation. For future directions, the demethylation potential of Hyphomicrobium assemblages and other nitrogen-fixing bacteria should be elucidated. Additionally, different organic matter inputs on paddy soils under constant and dynamic redox conditions could unravel the relationship between Hg (de)methylation, microbial carbon utilization and nitrogen cycling.
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Affiliation(s)
- Felizitas Boie
- 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
| | - Thomas F Ducey
- US Department of Agriculture, Coastal Plains Soil, Water, Plant Research Center, 2611 West Lucas Street, Florence, SC, USA
| | - Ying Xing
- 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; School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550002, PR China
| | - Jianxu Wang
- 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; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550082 Guiyang, P.R. 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.
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2
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Tuo P, Zhang Z, Du P, Hu L, Li R, Ren J. Changes in coal waste DOM chemodiversity and Fe/Al oxides during weathering drive the fraction conversion of heavy metals. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:172063. [PMID: 38552975 DOI: 10.1016/j.scitotenv.2024.172063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/14/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
The long-term accumulation of coal waste on the surface during natural weathering leads to the inevitable migration of heavy metals contained in the coal waste, which increases the likelihood of environmental contamination and health risks. Dissolved organic matter (DOM) and Fe/Al oxides play crucial roles in the transformation and bioavailability of heavy metals. Thus, we analyzed the Fe/Al oxide content and DOM molecular composition in coal waste with different degrees of weathering and explored the influence of DOM chemical diversity and Fe/Al oxides on the potential mobility of heavy metals. Results showed that weathering-driven decrease in Fe oxides (Fed, FeO, and Fep decreased from 82.4, 37.5, and 3.6 mg∙L-1 to 41.3, 24.7, and 2.3 mg∙L-1, respectively) led to decreases in the reducible fractions of V and Cr. The potential environmental risks of more toxic metals of Cd and As, also increased as a result of the residual fractions decreased to 32.6 % and 41.3 %, respectively. Weathering caused an increase in oxygen-to‑carbon ratio, double-bond equivalent, modified aromaticity index, nominal oxidation state of carbon, and molecular diversity and a decrease in (m/z)w and (H/C)w, suggesting that the DOM of highly weathered coal waste possessed high unsaturation, aromatic structures, hydrophilicity, and strong oxidative characteristics. Additionally, although VMF and CrMF showed significant negative correlations with O/C ratio, polyphenolic, carbohydrates, and condensed aromatics, pH remained a key environmental factor determining the potential environmental risks of V and Cr by changing the residual fractions. The mobilities of Cd and As were significantly negatively correlated with those of Fe/Al oxides, particularly Fed, FeO, Fep, and Alp. Our findings contribute to the understanding of the impact of weathering on the geochemical cycling of different coal waste components, providing priority options for environmental risk prevention and control in coal mining areas.
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Affiliation(s)
- Pinpeng Tuo
- Collaborative Innovation Center for Grassland Ecological Security Jointly Supported by the Ministry of Education of China and Inner Mongolia Autonomous Region, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Zongpeng Zhang
- Collaborative Innovation Center for Grassland Ecological Security Jointly Supported by the Ministry of Education of China and Inner Mongolia Autonomous Region, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Ping Du
- Technical Centre for Soil, Agricultural and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China
| | - Lijuan Hu
- Collaborative Innovation Center for Grassland Ecological Security Jointly Supported by the Ministry of Education of China and Inner Mongolia Autonomous Region, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Renyou Li
- Collaborative Innovation Center for Grassland Ecological Security Jointly Supported by the Ministry of Education of China and Inner Mongolia Autonomous Region, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Technical Centre for Soil, Agricultural and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China
| | - Jie Ren
- Collaborative Innovation Center for Grassland Ecological Security Jointly Supported by the Ministry of Education of China and Inner Mongolia Autonomous Region, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China.
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Zhang S, Xia M, Pan Z, Wang J, Yin Y, Lv J, Hu L, Shi J, Jiang T, Wang D. Soil organic matter degradation and methylmercury dynamics in Hg-contaminated soils: Relationships and driving factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 356:120432. [PMID: 38479282 DOI: 10.1016/j.jenvman.2024.120432] [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: 11/06/2023] [Revised: 02/01/2024] [Accepted: 02/17/2024] [Indexed: 04/07/2024]
Abstract
Biodegradation of soil organic matter (SOM), which involves greenhouse gas (GHG) emissions, plays an essential role in the global carbon cycle. Over the past few decades, this has become an important research focus, particularly in natural ecosystems. SOM biodegradation significantly affects contaminants in the environment, such as mercury (Hg) methylation, producing highly toxic methylmercury (MeHg). However, the potential link between GHG production from SOM turnover in contaminated soils and biogeochemical processes involving contaminants remains unclear. In this study, we investigated the dynamics of GHG, MeHg production, and the relationship between biogeochemical processes in soils from two typical Hg mining sites. The two contaminated soils have different pathways, explaining the significant variations in GHG and MeHg production. The divergence of the microbial communities in these two biogeochemical processes is essential. In addition to the microbial role, abiotic factors such as Hg species can significantly affect MeHg production. On the other hand, we found an inverse relationship between CH4 and MeHg, suggesting that carbon emission reduction policies and management could inadvertently increase the MeHg levels. This highlights the need for an eclectic approach to organic carbon sequestration and contaminant containment. These findings suggest that it is difficult to establish a general pattern to describe and explain the SOM degradation and MeHg production in contaminated soils within the specific scenarios. However, this study provides a case study and helpful insights for further understanding the links between environmental risks and carbon turnover in Hg mining areas.
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Affiliation(s)
- Siqi Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Meng Xia
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Zhaoyang Pan
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; 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
| | - Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Yongguang Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jitao Lv
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China.
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
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Qin D, Luo G, Qin A, He T, Wu P, Yin D. Selenium-phosphorus modified biochar reduces mercury methylation and bioavailability in agricultural soil. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123451. [PMID: 38281574 DOI: 10.1016/j.envpol.2024.123451] [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: 10/26/2023] [Revised: 12/22/2023] [Accepted: 01/24/2024] [Indexed: 01/30/2024]
Abstract
Biochar is a frequently employed for solidifying and stabilizing mercury (Hg) contamination in soil. However, it often results in an elevated presence of soil methylmercury (MeHg), which introduces new environmental risks. Consequently, there is a necessity for developing a safer modified biochar for use in Hg-contaminated soil. This study employed sodium selenite (at a safe dosage for soil) and hydroxyapatite to modify straw biochar (BC) based on the interaction between selenium (Se) and phosphorus (P). This process led to the formation of Se-modified biochar (Se-BC), P-modified biochar (P-BC), and Se and P co-modified biochar (Se-P-BC). Additionally, solvent adsorption experiments and pot experiments (BC/soil mass ratio: 0.5 %) were conducted to investigate the impacts of these soil amendments on soil Hg methylation and bioavailability. Se and P co-modification substantially increased the surface area, pore volume, and Hg adsorption capacity of BC. BC treatment increased the simulated gastric acid-soluble Hg, organo-chelated Hg, and MeHg in the soil. Conversely, Se-P-BC significantly reduced these forms of Hg in the soil, indicating that Se-P-BC can transform soil Hg into less bioavailable states. Among the different biochar treatments, Se-P-BC exhibited the most pronounced reductions in soil MeHg, total Hg, and MeHg in water spinach, achieving reductions of 63 %, 71 %, and 70 %, respectively. The co-modification of Se and P displayed a synergistic reduction effect in managing soil Hg pollution, which is associated with the increase of available Se in the soil due to phosphorus addition. The significantly reduced dissolved organic carbon and the abnormally high SO42- concentration in the soil of Se-P-BC treatment also inhibited Hg methylation and bioavailability in the soil. In summary, Se-P-BC substantially increased reduction percentage in plant Hg content while mitigating the risk of secondary pollution arising from elevated soil MeHg.
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Affiliation(s)
- Dongqiang Qin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Guangjun Luo
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Aming Qin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China.
| | - Pan Wu
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China
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Liu J, Qiu R, Wei X, Xiong X, Ren S, Wan Y, Wu H, Yuan W, Wang J, Kang M. MnFe 2O 4-biochar decreases bioavailable fractions of thallium in highly acidic soils from pyrite mining area. ENVIRONMENTAL RESEARCH 2024; 241:117577. [PMID: 37923109 DOI: 10.1016/j.envres.2023.117577] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 09/09/2023] [Accepted: 11/01/2023] [Indexed: 11/07/2023]
Abstract
The prevalence of toxic element thallium (Tl) in soils is of increasing concern as a hidden hazard in agricultural systems and food chains. In the present work, pure biochar (as a comparison) and jacobsite (MnFe2O4)-biochar composite (MFBC) were evaluated for their immobilization effects in Tl-polluted agricultural soils (Tl: ∼10 mg/kg). Overall, MFBC exhibited an efficient effect on Tl immobilization, and the effect was strengthened with the increase of amendment ratio. After being amended by MFBC for 15 and 30 days, the labile fraction of Tl in soil decreased from 1.55 to 0.97 mg/kg, and from 1.51 to 0.88 mg/kg, respectively. In addition, pH (3.05) of the highly acidic soil increased to a maximum of 3.97 after the immobilization process. Since the weak acid extractable and oxidizable Tl were the preponderantly mitigated fractions and displayed a negative correlation with pH, it can be inferred that pH may serve as one of the most critical factors in regulating the Tl immobilization process in MFBC-amended acidic soils. This study indicated a great potential of jacobsite-biochar amendment in stabilization and immobilization of Tl in highly acidic and Tl-polluted agricultural soils; and it would bring considerable environmental benefit to these Tl-contaminated sites whose occurrence has significantly increased in recent decades near the pyrite or other sulfide ore mining and smelting area elsewhere.
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Affiliation(s)
- Juan Liu
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Ruoxuan Qiu
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Xudong Wei
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China; Department of Agronomy, Food, Natural resources, Animals and Environment (DAFNAE) University of Padova, Agripolis Campus, Viale dell'Università, 16, 35020, Legnaro, PD, Italy
| | - Xinni Xiong
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Shixing Ren
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Yuebing Wan
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Hanyu Wu
- Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai, 519082, China
| | - Wenhuan Yuan
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China
| | - Jin Wang
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China.
| | - Mingliang Kang
- Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai, 519082, China.
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Chen J, Hu G, Liu J, Poulain AJ, Pu Q, Huang R, Meng B, Feng X. The divergent effects of nitrate and ammonium application on mercury methylation, demethylation, and reduction in flooded paddy slurries. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132457. [PMID: 37669605 DOI: 10.1016/j.jhazmat.2023.132457] [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: 04/28/2023] [Revised: 07/30/2023] [Accepted: 08/30/2023] [Indexed: 09/07/2023]
Abstract
The production of methylmercury (MeHg) in flooded paddy fields determines its accumulation in rice grains; this, in turn, results in MeHg exposure risks for not only rice-eating humans but also wildlife. Nitrogen (N) fertilizers have been widely applied in rice cultivation fields to supply essential nutrients. However, the effects of N fertilizer addition on mercury (Hg) transformations are not unclear. This limits our understanding of MeHg formation in rice paddy ecosystems. In this study, we spiked three Hg tracers (200HgII, Me198Hg, and 202Hg0) in paddy slurries fertilized with urea, ammonium, and nitrate. The influences of N fertilization on Hg methylation, demethylation, and reduction and the underlying mechanisms were elucidated. The results revealed that dissimilatory nitrate reduction was the dominant process in the incubated paddy slurries. Nitrate addition inhibited HgII reduction, HgII methylation, and MeHg demethylation. Competition between nitrates and other electron acceptors (e.g., HgII, sulfate, or carbon dioxide) under dark conditions was the mechanism underlying nitrate-regulated Hg transformation. Ammonium and urea additions promoted HgII reduction, and anaerobic ammonium oxidation coupled with HgII reduction (Hgammox) was likely the reason. This work highlighted that nitrate addition not only inhibited HgII methylation but also reduced the demethylation of MeHg and therefore may generate more accumulation of MeHg in the incubated paddy slurries. Findings from this study link the biogeochemical cycling of N and Hg and provide crucial knowledge for assessing Hg risks in intermittently flooded wetland ecosystems.
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Affiliation(s)
- Ji Chen
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Gongren Hu
- College of Chemical Engineering, Huaqiao University, Xiamen 361021, China
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Alexandre J Poulain
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Rong Huang
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Bo Meng
- 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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He Y, Yang X, Li Z, Wang T, Ma C, Wen X, Chen W, Zhang C. Aging rice straw reduces the bioavailability of mercury and methylmercury in paddy soil. CHEMOSPHERE 2023; 339:139711. [PMID: 37536532 DOI: 10.1016/j.chemosphere.2023.139711] [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: 05/10/2023] [Revised: 07/16/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023]
Abstract
Straw amendment is a prevalent agricultural practice worldwide, which can reduce air pollution and improve soil fertility. However, the impact of aging straw amendment on the bioavailability of mercury (Hg) and methylmercury (MeHg) in paddy soil remains unclear. To investigate this, incubation experiments were conducted using the diffusive gradient in thin-film technique. Results showed that amendments of dry-wet aging (DRS), photochemical aging (LRS), and freeze-thaw aging rice straw (FRS) reduced the bioavailable MeHg in paddy soil by 2.2-27.6%, 13.5-69.8%, and 23.5-86.1%, respectively, compared to fresh rice straw (RS) amendment. This result could be due to changes in soil properties such as soil pH and overlying water Fe and Mn as well as microbial abundance (including Clostridiaceae, Firmicutes, and Actinobacteriota). Simultaneously, The LRS and FRS amendments reduced bioavailable Hg in paddy soil by 20.0-40.8% and 17.1-48.6%, respectively, while DRS increased the bioavailable Hg by 15.8-120.0%. This could be attributed to changes in soil oxidation-reduction potential and overlying water SO42- content. Additionally, the results of sand culture experiments showed that the concentrations of Hg uptake by rice seedlings were 97.1-118.2%, 28.1-35.6%, and 198.0-217.1% higher in dissolved organic matter (DOM) derived from DRS, LRS, and FRS than RS, indicating that aging straw leached DOM may promote the Hg bioavailable when straw amendment. This result could be due to lower molecular weight and higher CO functional group content. These results provide new insight into how aging straw amendment affects the bioavailability of Hg and MeHg in paddy soil under different climates.
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Affiliation(s)
- Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Chi Ma
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
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8
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Tian X, Chai G, Xie Q, Li G. Response of methylmercury in paddy soil and paddy rice to pristine biochar: A meta-analysis and environmental implications. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 257:114933. [PMID: 37099962 DOI: 10.1016/j.ecoenv.2023.114933] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 04/14/2023] [Accepted: 04/16/2023] [Indexed: 05/08/2023]
Abstract
Biochar has received increased research attention due to its effectiveness in mitigating the potential risks of mercury (Hg) in agricultural soils. However, there is a lack of consensus on the effect of pristine biochar on the net production, availability, and accumulation of methylmercury (MeHg) in the paddy rice-soil system. As such, a meta-analysis with 189 observations was performed to quantitatively assess the effects of biochar on Hg methylation, MeHg availability in paddy soil, and the accumulation of MeHg in paddy rice. Results suggested that biochar application could significantly increase the production of MeHg in paddy soil by 19.01%; biochar could also decrease the dissolved and available MeHg in paddy soil by 88.64% and 75.69%, respectively. More importantly, biochar application significantly inhibited the MeHg accumulation in paddy rice by 61.10%. These results highlight that biochar could decrease the availability of MeHg in paddy soil and thus inhibit MeHg accumulation in paddy rice, although it might facilitate the net production of MeHg in paddy soil. Additionally, results also indicated that the biochar feedstock and its elementary composition significantly impacted the net MeHg production in paddy soil. Generally, biochar with a low carbon content, high sulfur content, and low application rate might be beneficial for inhibiting Hg methylation in paddy soil, meaning that Hg methylation depends on biochar feedstock. These findings suggested that biochar has great potential to inhibit MeHg accumulation in paddy rice, and further research should focus on selecting biochar feedstock to control Hg methylation potential and determine its long-term effects.
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Affiliation(s)
- Xiaosong Tian
- College of Resources, Environment and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China.
| | - Guanqun Chai
- Institute of Soil and Fertilizer, Guizhou Academy of Agricultural Sciences, Guiyang 550006, China
| | - Qing Xie
- College of Resources, Environment and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China.
| | - Guanghui Li
- Chongqing Engineering Research Center for Soil Contamination Control and Remediation, Chongqing 400067, China
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Abdelhafiz MA, Liu J, Jiang T, Pu Q, Aslam MW, Zhang K, Meng B, Feng X. DOM influences Hg methylation in paddy soils across a Hg contamination gradient. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 322:121237. [PMID: 36758923 DOI: 10.1016/j.envpol.2023.121237] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/05/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Rice paddies provide optimum conditions for Hg methylation, and paddy soil is a hot spot for Hg methylation and the predominant source of methylmercury (MeHg) accumulated in rice grains. The role of dissolved organic matter (DOM) in controlling Hg bioavailability and methylation in rice paddy systems remains unclear. Paddy soils from eight various cultivation sites in China were chosen to investigate the variations in soil DOM and the influence of DOM concentration and optical characteristics on Hg methylation in rice paddy systems. In the present study, 151 rhizosphere soil samples were collected, and UV-Vis absorption and fluorescent spectroscopy were used to identify the optical properties of DOM. The relationship between MeHg and DOM's optical property indices revealed the production of MeHg consumes lower molecular weight DOM. Moreover, the correlation between DOM concentration and its optical characteristics highlighted the significant role of humic components on MeHg variability in paddy soil. Variation and correlation results demonstrated the allochthonous origin of DOM in the Hg-contaminated soil, with a higher molecular weight and humic character of DOM, as well as the dominant role of autochthonous DOM in promoting Hg methylation in uncontaminated soil. The current study indicated that soil organic matter and its dissolved fractions tend to limit Hg bioavailability and subsequently diminish MeHg production in contaminated paddy soils. Furthermore, the leading roles of allochthonous DOM in protecting MeHg from degradation and autochthonous DOM signatures in enhancing MeHg production in paddy soils. Overall, these findings provide insight into the correlative distributions of DOM and Hg along a Hg concentration gradient in paddy soil, thereby highlighting their potential role in controlling Hg bioavailability and regulating Hg methylation in the soil ecosystems.
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Affiliation(s)
- 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; Geology Department, Faculty of Science, Al-Azhar University, Assiut, 71524, Egypt
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Tao Jiang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Muhammad Wajahat Aslam
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Kun Zhang
- 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.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
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10
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Chen W, Yu Z, Yang X, Wang T, Li Z, Wen X, He Y, Zhang C. Unveiling the Role of Dissolved Organic Matter on the Hg Phytoavailability in Biochar-Amended Soils. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3761. [PMID: 36834455 PMCID: PMC9963283 DOI: 10.3390/ijerph20043761] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 06/13/2023]
Abstract
Biochar can effectively reduce the phytoavailability of mercury (Hg) in soil, but the mechanisms are not fully understood. In this study, the dynamic changes in Hg content adsorbed by the biochar (BC-Hg), Hg phytoavailability in the soil (P-Hg), and soil dissolved organic matter (DOM) characteristics were determined over a 60-day treatment period. Biochar obtained at 300 °C, 500 °C and 700 °C reduced the P-Hg concentration assessed by MgCl2 extraction by 9.4%, 23.5% and 32.7%, respectively. However, biochar showed a very limited adsorption on Hg, with the maximum BC-Hg content only accounting for 1.1% of the total amount. High-resolution scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) results showed that the proportion of Hg atoms in biochar after 60 d was barely detectable. Biochar treatment can shift soil DOM toward higher aromatic content and molecular weight. Additionally, the addition of high-temperature biochar increased more humus-like components, but low-temperature biochar increased more protein-like components. Correlation analysis and partial least squares path modeling (PLS-PM) showed that biochar promoted humus-like fractions formation to reduce the Hg phytoavailability. This research has deepened the understanding of the mechanisms by which biochar stabilizes Hg in agricultural soils.
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Affiliation(s)
- Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zhigang Yu
- Australian Centre for Water and Environmental Biotechnology (Formerly AWMC), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
- Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
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11
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Yin D, Zhou X, He T, Wu P, Ran S. Remediation of Mercury-Polluted Farmland Soils: A Review. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 109:661-670. [PMID: 35690951 DOI: 10.1007/s00128-022-03544-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) bioaccumulation in Hg-polluted farmlands poses high health risk for humans and wildlife, and remediation work is urgently needed. Here, we first summarize some specific findings related to the environmental process of Hg in Hg-polluted farmlands, and distinguish the main achievements and deficiencies of available remediation strategies in recent studies. Results demonstrate that farmland is a sensitive area with vibrant Hg biogeochemistry. Current remediation methods are relatively hysteretic whether in mechanism understanding or field application, and deficient for large-scale Hg-polluted farmlands in view of safety, efficiency, sustainability, and cost-effectiveness. New perspectives including environment-friendly functional materials, assisted phytoremediation and agronomic regulations are worthy of further study as their key roles in reducing Hg exposure risk and protecting agricultural sustainability.
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Affiliation(s)
- Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Pan Wu
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China.
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
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