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Zhong S, Li X, Fang L, Bai J, Gao R, Huang Y, Huang Y, Liu Y, Liu C, Yin H, Liu T, Huang F, Li F. Multifunctional Roles of Zinc in Cadmium Transport in Soil-Rice Systems: Novel Insights from Stable Isotope Fractionation and Gene Expression. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:12467-12476. [PMID: 38966939 DOI: 10.1021/acs.est.4c01851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
The effect of Zn on Cd accumulation in rice varies under flooding and drainage conditions, and the underlying mechanism during uptake and transport from the soil to grains remains unclear. Isotope fractionation and gene expression were investigated using pot experiments under distinct water regimes and with Zn addition to gain a deeper understanding of the molecular effects of Zn on Cd uptake and transport in rice. The higher OsHMA2 expression but constitutively lower expression of zinc-regulated, iron-regulated transporter-like protein (ZIP) family genes in roots under the drainage regime than the flooding regime caused the enrichment of nonheavy Zn isotopes in the shoots relative to roots but minimally affected Cd isotopic fractionation. Drainage regime seem to exert a striking effect on the root-to-shoot translocation of Zn rather than Cd, and increased Zn transport via OsHMA2. The changes in expression patterns in response to Zn addition were similar to those observed upon switching from the flooding to drainage regime, except for OsNRAMP1 and OsNRAMP5. However, soil solution-to-rice plants and root-to-shoot fractionation toward light Zn isotopes with Zn addition (Δ66Znrice plant-soil solution = -0.49 to -0.40‰, Δ66Znshoot-root = -0.36 to -0.27‰) indicated that Zn transport occurred via nonspecific uptake pathways and OsHMA2, respectively. Accordingly, the less pronounced and minimally varied Cd isotope fractionation suggested that OsNRAMP5 and OsHMA2 are crucial for Cd uptake and root-to-shoot transport, respectively, facilitating Cd accumulation in grains. This study demonstrated that a high Zn supply promotes Cd uptake and root-to-shoot transport in rice by sharing distinct pathways, and by utilizing a non-Zn-sensitive pathway with a high affinity for Cd.
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Affiliation(s)
- Songxiong Zhong
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Xiaomin Li
- SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China
| | - Liping Fang
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Jianghao Bai
- Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Ruichuan Gao
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Yao Huang
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Yingmei Huang
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Yuhui Liu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Chuanping Liu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Haoming Yin
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Tongxu Liu
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Fang Huang
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Fangbai Li
- Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
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Yuan S, Jiang Y, Chen P, Tu N, Zhou W, Yi Z. Difference in Cd accumulation among varieties with different growth duration corresponding to typical agro-climate condition in rice ratooning system. FRONTIERS IN PLANT SCIENCE 2024; 15:1383428. [PMID: 38779068 PMCID: PMC11109407 DOI: 10.3389/fpls.2024.1383428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/22/2024] [Indexed: 05/25/2024]
Abstract
Introduction The ratoon rice planting area is gradually expanding, but there has been relatively little research on ratoon rice grains contaminated with Cd. Methods In this study, five ratoon rice varieties were selected and divided into three groups according to early-maturity (growth duration: 100-110 days), mid-maturity (growth duration: 110-120 days) and late-maturity (growth duration: 120-130 days) varieties. Field experiments were done to study the differences in Cd accumulation among ratoon rice varieties with different growth duration. Results The results showed that the Cd accumulation and concentration of grains spikelet at each growth stage in the main crop were in the order of late-maturity > mid-maturity > early-maturity varieties. However, the trends in Cd concentration and accumulation in grains spikelet during the ratoon crop were the opposite. Analysis found that as the growth duration of the variety extended, the accumulated temperature and daily average temperature in the main crop increased, which significantly increased the translocation factors of Cd from root, stem, and leaf to grains spikelet, and increased the daily average Cd accumulation rate in grains spikelet. The daily average temperature in the ratoon crop increased as the growth duration shortened. The early-maturity variety had higher Cd accumulation in stubble, which promoted the translocation of Cd from the root, stem, and leaf of the plant to the grains spikelet. Discussion Therefore, appropriately shortening the growth duration of the main crop and extending the growth duration of the ratoon crop are important ways to reduce Cd accumulation in ratoon rice in areas with mild Cd pollution.
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Affiliation(s)
| | | | | | | | - Wenxin Zhou
- College of Agronomy, Hunan Agricultural University, Changsha, China
| | - Zhenxie Yi
- College of Agronomy, Hunan Agricultural University, Changsha, China
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Li C, Li G, Wang Y, Wang J, Liu H, Gao W, Qin S, Sui F, Fu H, Zhao P. Supplementing two wheat genotypes with ZnSO 4 and ZnO nanoparticles showed differential mitigation of Cd phytotoxicity by reducing Cd absorption, preserving root cellular ultrastructure, and regulating metal-transporter gene expression. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 206:108199. [PMID: 38100890 DOI: 10.1016/j.plaphy.2023.108199] [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: 07/31/2023] [Revised: 10/12/2023] [Accepted: 11/13/2023] [Indexed: 12/17/2023]
Abstract
Cadmium (Cd) contamination is a serious challenge in agricultural soils worldwide, resulting in Cd entering the food chain mainly through plant-based food and threatening human health. Minimizing Cd bioaccumulation in wheat is an important way to prevent Cd hazards to humans. Hydroponic and pot experiments were conducted to comprehensively evaluate the effects of zinc sulfate (ZnSO4) and zinc oxide nanoparticles (nZnO) on Cd uptake, translocation, subcellular distribution, cellular ultrastructure, and gene expression in two wheat genotypes that differ in grain Zn accumulation. Results showed that high-dose nZnO significantly reduced root Cd concentration (52.44%∼56.85%) in two wheats, in contrast to ZnSO4. The S216 exhibited higher tolerance to Cd compared to Z797. Importantly, Zn supplementation enhanced Cd sequestration into vacuoles and binding to cell walls, which conferred stability to ultracellular structures and photosynthetic apparatus. Down-regulation of influx transporter (TaHMA2 and TaLCT1) and up-regulation of efflux transporters (TaTM20 and TaHMA3) in Z797 might contribute to Zn-dependent alleviation of Cd toxicity and enhance its Cd tolerance. Down-regulation of ZIP transporters (TaZIP3, -5, and -7) might contribute to an increase in root Zn concentration and inhibit Cd absorption. Additionally, soil Zn provided an effective strategy for the reduction of grain Cd concentrations in both wheats, with a reduction of 26%∼32% (high ZnSO4) and 11%∼67% (high nZnO), respectively. Collectively, these findings provide new insights and perspectives on the mechanisms of Cd mitigation in wheats with different Zn fertilizers and demonstrate that the effect of nZnO in mitigating Cd stress is greater than that of ZnSO4 fertilizers.
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Affiliation(s)
- Chang Li
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Guangxin Li
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Yun Wang
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Jun Wang
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Hongen Liu
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Wei Gao
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Shiyu Qin
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Fuqing Sui
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Haichao Fu
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China
| | - Peng Zhao
- College of Resources and Environmental, Henan Agricultural University, Zhengzhou, 450046, China; Key Laboratory of Soil Pollution Control and Remediation of Henan Province, Zhengzhou, 450046, China.
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Zhao P, Huang P, Yan X, Chukwuma A, Yang S, Yang Z, Li H, Yang W. Inhibitory effect of exogenous mineral elements (Si, P, Zn, Ca, Mn, Se, Fe, S) on rice Cd accumulation and soil Cd bioavailability in Cd-contaminated farmlands: A meta-analysis. CHEMOSPHERE 2023; 343:140282. [PMID: 37758089 DOI: 10.1016/j.chemosphere.2023.140282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/14/2023] [Accepted: 09/24/2023] [Indexed: 10/01/2023]
Abstract
A promising strategy for safely remediating Cd-contaminated farmland has been the application of mineral elements, which can reduce Cd accumulation in rice and inhibit its bioavailability in Cd-contaminated farmlands. However, there is still a lack of systematic and quantitative evaluations regarding how different mineral elements affect rice Cd accumulation and soil Cd bioavailability. Here, a meta-analysis was conducted based on 1062 individual observations from 137 published works to explore the effects of Si, P, Zn, Ca, Mn, Se, Fe and S in rice Cd accumulation and soil Cd bioavailability, we aimed to identify key factors that control the reduction of Cd concentration in rice grains. The results showed that the presence of exogenous elements had dramatically reduced rice grains Cd concentrations in the following decreasing order: Fe (43.03%) > P (38.45%) > Si (33.24%) > Ca (31.90%) > Se (29.83%) > Zn (25.95%) > Mn (23.26%) > S (18.78%). The elements of Ca, P and Si had strongly reduced Cd bioavailability in soils by 29.87%, 27.80% and 22.70%, respectively. The effects of these elements on Cd bioavailability appeared to be controlled by soil physio-chemical properties, such as pH, soil organic carbon (SOC) but also water management, application amounts and elemental forms. Overall, this study provides valuable insights into the potential of using exogenous mineral elements to mitigate Cd contamination in rice and farmlands, and facilitates the selection and application of mineral elements for the safe utilization of Cd-contaminated farmlands, taking into account soil properties and other factors that affect their effect.
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Affiliation(s)
- Pengwei Zhao
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China
| | - Peicheng Huang
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China
| | - Xiao Yan
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China
| | - Arinzechi Chukwuma
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China
| | - Sen Yang
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China
| | - Zhihui Yang
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha 410083, Hunan, PR China
| | - Huan Li
- Hunan University of Technology and Business, Changsha 410083, Hunan, PR China.
| | - Weichun Yang
- School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, PR China; Chinese National Engineering Research Centre for Control & Treatment of Heavy Metal Pollution, Changsha 410083, Hunan, PR China.
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Huang H, Lv Y, Tian K, Shen Y, Zhu Y, Lu H, Li R, Han J. Influence of sulfate reducing bacteria cultured from the paddy soil on the solubility and redox behavior of Cd in a polymetallic system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 901:166369. [PMID: 37597556 DOI: 10.1016/j.scitotenv.2023.166369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/29/2023] [Accepted: 08/15/2023] [Indexed: 08/21/2023]
Abstract
As a toxic heavy metal, cadmium (Cd) easily enters into rice while rice grains greatly contribute to the dietary Cd intake in the populations consuming rice as a staple food. The availability of Cd in paddy soil determines the accumulation of grain Cd. Soil drainage leads to the remobilization of Cd, increasing bioavailability of Cd. In contrast, soil flooding results in little contribution of soil Cd to grain Cd, which is generally attributed to sulfate reduction induced by sulfate-reducing bacteria (SRB) in paddy soils. However, effects of SRB cultured from the paddy soil on the solubility and redox behavior of Cd have been seldom investigated before. Here, we used SRB enrichment cultures to investigate the temporal dynamics of Cd2+. The results showed that SRB enrichment cultures efficiently reduced solution redox potential (Eh) to less than -100 mV and gradually increased pH to neutral, demonstrating their ability to create a good anaerobic environment. The solubility of Cd obviously decreased in the anaerobic phase and Cd2+ was transformed into poorly dissolved CdS near the SRB cell wall edge. The addition of Zn2+ and/or Fe2+ further improved the decrease in Cd solubility and facilitated the formation of polymetallic sulfides as a consequence of promoting the production of S0 and dissolved sulfides (S2-/HS-) and the transformation of S0 into S2-/HS-. Little of Cd was detected in the media upon reoxidation, which was probably due to the high pH and the interaction between CdS and ZnS/FeS. Conclusively, these results demonstrate the detailed dynamic processes that explain the essential role of SRB in regulating the redox dynamics of chalcophile heavy metals and their bioavailability in paddy soils.
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Affiliation(s)
- Hui Huang
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China; College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 223100, China.
| | - Yuwei Lv
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Kunkun Tian
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yu Shen
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Yongli Zhu
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
| | - Haiying Lu
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
| | - Ronghua Li
- College of Natural Resource and Environment, Northwest A & F University, Yangling 712100, China.
| | - Jiangang Han
- College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China; National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 223100, China
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Machine learning methods to predict cadmium (Cd) concentration in rice grain and support soil management at a regional scale. FUNDAMENTAL RESEARCH 2023. [DOI: 10.1016/j.fmre.2023.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
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Wang Y, Xu Y, Liang X, Li L, Huang Q. Soil addition of MnSO 4 reduces wheat Cd accumulation by simultaneously increasing labile Mn and decreasing labile Cd concentrations in calcareous soil: A two-year pot study. CHEMOSPHERE 2023; 317:137900. [PMID: 36669536 DOI: 10.1016/j.chemosphere.2023.137900] [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: 11/12/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
Cadmium (Cd) pollution of wheat fields is a serious environmental and health problem that warrants attention. Manganese (Mn)-containing materials are considered effective for inhibiting Cd accumulation in Cd-contaminated acidic soils. However, information on the long-term remediation effects of Mn fertilizers on Cd accumulation in wheat and on the microbial community in calcareous soils remain limited. Here, a two-year pot experiment was conducted to assess the performance of 0.05-0.2% MnSO4 addition in Cd-contaminated calcareous soils (total Cd concentration: 3.65 mg/kg) on Cd accumulation in wheat as well as on the soil bacterial community. The formation of Mn oxides and transformation of exchangeable Cd to stable Cd fractions confirmed that the application of MnSO4 significantly decreased CaCl2-extractable Cd concentrations in soil (0-47.08%). In addition, MnSO4 addition improved the antagonistic effect of Cd and Mn ions in the wheat rhizosphere by increasing the available Mn concentration in the soil (1.04-3.52 times), thereby significantly reducing wheat Cd accumulation by 24.66-54.70%. Notably, the addition of MnSO4 did not affect the richness and diversity (P > 0.05) but altered the composition and function of bacterial communities, especially those involved in metabolism and genetic information processing. Importantly, the effects of MnSO4 on Cd immobilization in soil (10.66-47.08%) and the inhibition of Cd accumulation in wheat (12.13-54.30%) can last for two years after one addition. Furthermore, the maximum decrease in Cd concentration in grains was found in the low-Cd wheat cultivar, with values of 31.39-54.70% and 19.94-54.30% in the first and second years, respectively. Based on the present findings, the combination of MnSO4 with a low-Cd wheat cultivar is effective for the safe utilization of Cd-contaminated calcareous soils.
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Affiliation(s)
- Yale Wang
- School of Environmental Engineering, Henan University of Technology, Zhengzhou, Henan, 450001, China; Henan International Joint Laboratory of Environmental Pollution, Remediation and Grain Quality Security, Zhengzhou, Henan, 450001, China; Institute for Carbon Neutrality, Henan University of Technology, Zhengzhou, Henan, 450001, China
| | - Yingming Xu
- Innovation Team of Remediation of Heavy Metal Contaminated Farmlands, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China.
| | - Xuefeng Liang
- Innovation Team of Remediation of Heavy Metal Contaminated Farmlands, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China
| | - Liping Li
- School of Environmental Engineering, Henan University of Technology, Zhengzhou, Henan, 450001, China; Henan International Joint Laboratory of Environmental Pollution, Remediation and Grain Quality Security, Zhengzhou, Henan, 450001, China; Institute for Carbon Neutrality, Henan University of Technology, Zhengzhou, Henan, 450001, China
| | - Qingqing Huang
- Innovation Team of Remediation of Heavy Metal Contaminated Farmlands, Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China.
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Lyu C, Li L, Liu X, Zhao Z. Rape straw application facilitates Se and Cd mobilization in Cd-contaminated seleniferous soils by enhancing microbial iron reduction. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 310:119818. [PMID: 35870532 DOI: 10.1016/j.envpol.2022.119818] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/11/2022] [Accepted: 07/17/2022] [Indexed: 06/15/2023]
Abstract
Many naturally seleniferous soils are faced with Cd contamination problem, which severely limits crop cultivation in these areas. Straw returning has been widely applied in agricultural production due to its various benefits to soil physicochemical properties, soil fertility, and crops yield. However, effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils remain largely unclear. Therefore, the effects of straw application on the fates of Se and Cd in Cd-contaminated seleniferous soils were investigated in this study. The results showed that iron reduction driven by Clostridium and Anaeromyxbacter was responsible for the variations in Se and Cd fates in soil. Straw application respectively increased the gene copy numbers of Clostridium and Anaeromyxbacter by 19.5-56.3% and 33.6-39.8%, thus promoting iron reductive dissolution, eventually resulting in a high release amount of Se and Cd from Fe(III) (oxyhydr) oxides. Under reducing conditions, the released Cd was adsorbed by the newly formed metal sulfides or reacted with sulfides to generate CdS precipitates. Straw application decreased the soil exchangeable Se and soil exchangeable Cd concentration during flooding phase. However, straw application significantly increased Se/Cd in soil solution which had the highest bioavailability during flooding. In addition, straw application increased soil exchangeable Se concentration, but it had no significant effects on soil exchangeable Cd concentration after soil drainage. Taken together, straw application increased Se bioavailability and Cd mobility. Therefore, straw application is an effective method for improving Se bioavailability, but it is not suitable for the application to Cd-contaminated paddy soils. In the actual agricultural production, straw could be applied in seleniferous soils to improve Se bioavailability. At the same time, straw application should be cautious to avoid the release of Cd from Cd-contaminated soil.
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Affiliation(s)
- Chenhao Lyu
- Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for New-Type Fertilizer, Wuhan, 430070, China
| | - Lei Li
- Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for New-Type Fertilizer, Wuhan, 430070, China
| | - Xinwei Liu
- Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for New-Type Fertilizer, Wuhan, 430070, China
| | - Zhuqing Zhao
- Microelement Research Center, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for New-Type Fertilizer, Wuhan, 430070, China.
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