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Hao W, Xu X, Qiu G, Dong X, Zhu F, Han J, Liang L, Chen Z. Predictive modeling of methylmercury in rice (Oryza sativa L.) and species-sensitivity-distribution-based derivation of the threshold of soil mercury in karst mountain areas. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2024; 46:157. [PMID: 38592345 DOI: 10.1007/s10653-024-01944-1] [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: 12/06/2023] [Accepted: 02/26/2024] [Indexed: 04/10/2024]
Abstract
The bioavailable mercury (Hg) in the soil is highly active and can affect the formulation of methyl-Hg (MeHg) in soil and its accumulation in rice. Herein, we predicted the concentration of MeHg in rice using bioavailable Hg extracted from soils; additionally, we determined the threshold value of soil Hg in karst mountain areas based on species sensitivity distribution. The bioavailable Hg was extracted using calcium chloride, hydrochloric acid (HCl), diethylenetriaminepentaacetic acid mixture, ammonium acetate, and thioglycolic acid. Results showed that HCl is the best extractant, and the prediction model demonstrated good predictability of the MeHg concentration in rice based on the HCl-extractable Hg, pH, and soil organic matter (SOM) data. Compared with the actual MeHg concentration in rice, approximately 99% of the predicted values (n = 103) were within the 95% prediction range, indicating the good performance of the rice MeHg prediction model based on soil pH, SOM, and bioavailable Hg in karst mountain areas. Based on this MeHg prediction model, the safety threshold of soil Hg was calculated to be 0.0936 mg/kg, which is much lower than the soil pollution risk screening value of agricultural land (0.5 mg/kg), suggesting that a stricter standard should be applied regarding soil Hg in karst mountain areas. This study presents the threshold of soil Hg pollution for rice safety in karst mountain areas, and future studies should target this threshold range.
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Affiliation(s)
- Wanbin Hao
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550025, China
| | - Xiaohang Xu
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Xian Dong
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550025, China
| | - Fang Zhu
- Guiyang Healthcare Vocational University, Guiyang, 550081, China
| | - Jialiang Han
- College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang, 550025, Guizhou, China
| | - Longchao Liang
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550025, China.
| | - Zhuo Chen
- School of Chemistry and Materials Science, Guizhou Normal University, Guiyang, 550025, China.
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2
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Li S, Li Z, Wu M, Zhou Y, Tang W, Zhong H. Mercury transformations in algae, plants, and animals: The occurrence, mechanisms, and gaps. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 911:168690. [PMID: 38000748 DOI: 10.1016/j.scitotenv.2023.168690] [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: 10/16/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023]
Abstract
Mercury (Hg) is a global pollutant showing potent toxicity to living organisms. The transformations of Hg are critical to global Hg cycling and Hg exposure risks, considering Hg mobilities and toxicities vary depending on Hg speciation. Though currently well understood in ambient environments, Hg transformations are inadequately explored in non-microbial organisms. The primary drivers of in vivo Hg transformations are far from clear, and the impacts of these processes on global Hg cycling and Hg associated health risks are not well understood. This hinders a comprehensive understanding of global Hg cycling and the effective mitigation of Hg exposure risks. Here, we focused on Hg transformations in non-microbial organisms, particularly algae, plants, and animals. The process of Hg oxidation/reduction and methylation/demethylation in organisms were reviewed since these processes are the key transformations between the dominant Hg species, i.e., elemental Hg (Hg0), divalent inorganic Hg (IHgII), and methylmercury (MeHg). By summarizing the current knowledge of Hg transformations in organisms, we proposed the potential yet overlooked drivers of these processes, along with potential challenges that hinder a full understanding of in vivo Hg transformations. Knowledge summarized in this review would help achieve a comprehensive understanding of the fate and toxicity of Hg in organisms, providing a basis for predicting Hg cycles and mitigating human exposure.
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Affiliation(s)
- Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Zhuoran Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Mengjie Wu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
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3
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Huang Y, Yi J, Huang Y, Zhong S, Zhao B, Zhou J, Wang Y, Zhu Y, Du Y, Li F. Insights into the reduction of methylmercury accumulation in rice grains through biochar application: Hg transformation, isotope fractionation, and transcriptomic analysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 340:122863. [PMID: 37925005 DOI: 10.1016/j.envpol.2023.122863] [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: 07/10/2023] [Revised: 10/07/2023] [Accepted: 11/01/2023] [Indexed: 11/06/2023]
Abstract
Methylmercury (MeHg), a potent neurotoxin, easily moves from the soil into rice plants and subsequently accumulates within the grains. Although biochar can reduce MeHg accumulation in rice grains, the precise mechanism underlying biochar-mediated responses to mercury (Hg) stress, specifically regarding MeHg accumulation in rice, remains poorly understood. In the current study, we employed a 4% biochar amendment to remediate Hg-contaminated paddy soil, elucidate the impacts of biochar on MeHg accumulation through a comprehensive analysis involving Hg isotopic fractionation and transcriptomic analyses. The results demonstrated that biochar effectively lowered the levels of MeHg in paddy soils by decreasing bioavailable Hg and microbial Hg methylation. Furthermore, biochar reduced the uptake and translocation of MeHg in rice plants, ultimately leading to a reduction MeHg accumulation in rice grains. During the process of total mercury (THg) uptake, biochar induced a more pronounced negative isotope fractionation magnitude, whereas the effect was less pronounced during the upward transport of THg. Conversely, biochar caused a more pronounced positive isotope fractionation magnitude during the upward transport of MeHg. Transcriptomics analyses revealed that biochar altered the expression levels of genes associated with the metabolism of cysteine, glutathione, and metallothionein, cell wall biogenesis, and transport, which possibly enhance the sequestration of MeHg in rice roots. These findings provide novel insights into the effects of biochar application on Hg transformation and transport, highlighting its role in mitigating MeHg accumulation in rice.
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Affiliation(s)
- Yingmei Huang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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; Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou, 510405, China
| | - Jicai Yi
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yao Huang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Songxiong Zhong
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Bin Zhao
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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; Norwegian University of Life Sciences, Department of Environmental Sciences, 5003, N-1432 Ås, Norway
| | - Jing Zhou
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Yuxuan Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Yiwen Zhu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Yanhong Du
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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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4
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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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5
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Zhang Y, Wang X, Yang Y, Huang Y, Li X, Hu S, Liu K, Pang Y, Liu T, Li F. Retention and transformation of exogenous Hg in acidic paddy soil under alternating anoxic and oxic conditions: Kinetic and mechanistic insights. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 323:121335. [PMID: 36828356 DOI: 10.1016/j.envpol.2023.121335] [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: 11/11/2022] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
To estimate the risks and developing remediation strategies for the mercury (Hg)-contaminated soils, it is crucial to understand the mechanisms of Hg transformation and migration in the redox-changing paddy fields. In present study, a Hg-spiked acidic paddy soil (pH 4.52) was incubated under anoxic conditions for 40 d and then under oxic conditions for 20 d. During anoxic incubation, the water-soluble, exchangeable, specifically adsorbed, and fulvic acid-complexed Hg decreased sharply, whereas the humic acid-complexed Hg, organic, and sulfide-bound Hg gradually increased, which were mainly ascribed to the enhanced adsorption on the surface of soil minerals with an increase in soil pH, complexation by organic matters, precipitation as HgS, and absorption by soil colloids triggered by reductive dissolution of Fe(III) oxides. By contrast, after oxygen was introduced into the system, a gradual increase in available Hg occurred with decreasing soil pH, decomposition of organic matters and formation of Fe(III) oxides. A kinetic model was established based on the key elementary reactions to quantitatively estimate transformation processes of Hg fractions. The model matched well with the modified Tessier sequential extraction data, and suggested that large molecular organic matter and humic acid dominated Hg complexation and immobilization in acidic paddy soils. The content of methylmercury increased and reached its peak on anoxic 20 d. Sulfate-reducing bacteria Desulfovibrio and Desulfomicrobium were the major Hg methylating bacteria in the anoxic stage whereas demethylating microorganisms Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_12 began to grow after oxygen was introduced. These new dynamic results provided new insights into the exogenous Hg transformation processes and the model could be used to predict Hg availability in periodically flooded acidic paddy fields.
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Affiliation(s)
- Yufan Zhang
- 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; School of Environment, South China Normal University, Guangzhou, 510006, China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Xiangqin Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Yang Yang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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; School of Environment, South China Normal University, Guangzhou, 510006, China
| | - Shiwen Hu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Kexue Liu
- School of Resources and Planning, Guangzhou Xinhua University, Guangzhou, 510310, China
| | - Yan Pang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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
| | - Tongxu Liu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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.
| | - Fangbai Li
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, 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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6
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Yang Q, Guo Y, Xiang Y, Chen L, Liu G, Liu Y, Shi J, Hu L, Liang Y, Yin Y, Cai Y, Jiang G. Toward efficient bioremediation of methylmercury in sediment using merB overexpressed Escherichia coli. WATER RESEARCH 2023; 229:119502. [PMID: 36549184 DOI: 10.1016/j.watres.2022.119502] [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: 06/02/2022] [Revised: 11/26/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Sediment is the primary hotspot for microbial production of toxic and bio-accumulative methylmercury (MeHg). Common remediation strategies such as sediment dredging and capping can be too expensive and cannot degrade MeHg efficiently. Here, we constructed an Escherichia coli strain overexpressing merB gene (DH5α J23106) and assessed the effectiveness of this recombinant strain in degradation of MeHg in culture medium and sediment. DH5α J23106 can efficiently degrade MeHg (with initial concentration from 0.01 to 50 ng/mL) to more than 81.6% in a culture medium under anoxic and oxic conditions. Enriched isotope addition (199HgCl2) revealed that this recombinant strain can degrade 78.6% of newly produced Me199Hg in actual sediment, however the biodegradation decreased to 36.3% for intrinsic MeHg. Degradation of spiked MeHg after aging in anoxic and oxic sediments further demonstrated DH5α J23106 can efficiently degrade newly produced MeHg and the degradation decreased with aging significantly, especially for oxic sediment. Eight sediments were further assessed for the biodegradation of aged MeHg by DH5α J23106 under oxic conditions, with degradation ratios ranging from 9.0% to 66.9%. When combined with (NH4)2S2O3 leaching, the degradation of MeHg increased by 15.8-38.8% in on-site and off-site modes through enhanced MeHg bioavailability in some of these sediments. Thus, this recombinant strain DH5α J23106 can degrade MeHg efficiently and have the potential for remediating bioavailable MeHg in contaminated sediments.
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Affiliation(s)
- Qingqing Yang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, Institute of Environment and Health, Jianghan University, Wuhan, China; School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yingying Guo
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Lufeng Chen
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, Institute of Environment and Health, Jianghan University, Wuhan, China; School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States
| | - Yanwei Liu
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jianbo Shi
- 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
| | - Yong Liang
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, Institute of Environment and Health, Jianghan University, Wuhan, China; School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, Institute of Environment and Health, Jianghan University, Wuhan, China.
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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7
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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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8
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Liu T, Man Y, Li P, Zhang H, Cheng H. A Hydroponic Study on Effect of Zinc Against Mercury Uptake by Triticale: Kinetic Process and Accumulation. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 108:359-365. [PMID: 34181031 DOI: 10.1007/s00128-021-03298-1] [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: 04/18/2021] [Accepted: 06/09/2021] [Indexed: 06/13/2023]
Abstract
We investigated the ability of triticale uptake of Mercury (Hg), clarified whether triticale root uptake of Hg2+ via Zinc (Zn2+) transports, using hydroponic experiments. At 25℃, when Hg exposure in solution was lower than 20 μM, Hg concentration in the roots can be better described by a hyperbolic function, which shows a saturable characteristic. Under ice-cold (< 2℃) conditions, a nonsaturable (linear) component was found. Low exposure of Zn2+ (0-1 μM) inhibited plant Hg uptake when Hg exposure in the solution ranged from 1 to 10 μM, it showed an antagonistic effect of Zn on plant uptake of Hg. When Hg exposure was 20 μM, it revealed a synergistic effect of Zn on plant uptake of Hg, Hg in the root increased at the Zn (1 μM) exposure in the solution. Our results will deepen the understanding of Hg transfer in the soil-plant system.
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Affiliation(s)
- Ting Liu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yi Man
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China
| | - Hua Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, People's Republic of China
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Lv W, Zhan T, Abdelhafiz MA, Feng X, Meng B. Selenium-amended biochar mitigates inorganic mercury and methylmercury accumulation in rice (Oryza sativa L.). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 291:118259. [PMID: 34600068 DOI: 10.1016/j.envpol.2021.118259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/22/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
Rice, as a dominant crop in China and Asia, can be a major route of methylmercury (MeHg) exposure for humans in inland China, especially in those living in mercury (Hg) polluted areas. Soil is the most prominent MeHg accumulation source for rice grains. The development of management practices to reduce MeHg in rice grains is crucial. This study explored the mitigation effect of biochar (BC) and sodium selenite-amended biochar (BC + Se) on MeHg production in paddy soil and accumulation in rice. Mercury-contaminated soil was treated with 1% and 5% of both BC and BC + Se. Soil MeHg concentration slightly increased under 1% BC/BC + Se compared to control soil but decreased at the rate of 5%. Moreover, soil phytoavailable MeHg (P-MeHg) diminished as the amount of Se-amended BC increased. BC + Se effectively mitigated MeHg accumulation in rice grains. The highest average contents of MeHg and inorganic Hg (IHg) in rice seeds were found in the control samples, followed by the 1%-BC, 5%-BC, 1%-BC + Se, and 5%-BC + Se samples. Under the 5%-BC + Se treatment, rice MeHg levels were reduced significantly (94%) compared to the control, and P-MeHg concentrations in soil were lower than all the other experimental groups throughout the rice-growing season. These results demonstrate the effectiveness of BC + Se in reducing MeHg and IHg accumulation in rice and could be employed for remediation of Hg polluted paddies.
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Affiliation(s)
- Wenqiang Lv
- School of Geography and Resources, Guizhou Education University, Guiyang, Guizhou, 550018, China
| | - Tianli Zhan
- Institute of Mountain Resources of Guizhou Province, Guiyang, 550001, 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; Geology Department, Faculty of Science, Al-Azhar University, Assiut, 71524, Egypt
| | - 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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10
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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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11
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Wang Y, Zhang Y, Ok YS, Jiang T, Liu P, Shu R, Wang D, Cao X, Zhong H. Biochar-impacted sulfur cycling affects methylmercury phytoavailability in soils under different redox conditions. JOURNAL OF HAZARDOUS MATERIALS 2021; 407:124397. [PMID: 33183839 DOI: 10.1016/j.jhazmat.2020.124397] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 10/19/2020] [Accepted: 10/26/2020] [Indexed: 06/11/2023]
Abstract
Recently, there has been increasing interest in reducing methylmercury (MeHg) phytoavailability using biochar, although the underlying mechanisms are not fully understood. By combining lab-scale batch incubation with pot and field validations, we demonstrate that biochar-impacted sulfur cycling in soils and MeHg-soil binding play key roles in controlling MeHg phytoavailability. (1) Under anoxic conditions, biochar-associated sulfate and biochar-facilitated microbial sulfate reduction enhanced the production of reduced inorganic sulfur species as acid-volatile sulfide (AVS) in soils by 122%, facilitating MeHg binding with soils and thus reducing MeHg phytoavailability. (2) In contrast, under oxic conditions, the reduced inorganic sulfur was oxidized (resulting in a 68-91% decrease in AVS), which released soil-bound MeHg and increased MeHg phytoavailability. The proposed mechanisms could explain the distinct effects of biochar amendment on MeHg bioaccumulation observed under anoxic (10-88% lower in rice grains) and oxic conditions (48-84% higher in wheat grains). Our results dispute the commonly held assumption that reduced MeHg phytoavailability under biochar amendment can be primarily attributed to MeHg-biochar binding. Therefore, the potential increased risk of MeHg in oxic soils following biochar amendment should be evaluated in more detail.
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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
| | - Yue Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Yong Sik Ok
- Korea Biochar Research Center, O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Tao Jiang
- College of Resources Environment, Southwest University, Chongqing 400716, PR China
| | - Peng Liu
- School of Environmental Studies, China University of Geosciences, 388 Lumo Rd., Wuhan 430074, PR China
| | - Rui Shu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Dingyong Wang
- College of Resources Environment, Southwest University, Chongqing 400716, PR China
| | - Xinde Cao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, 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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12
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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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13
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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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14
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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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15
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Li Y, Guan J, Zhao J, Li B, Li YF, Gao Y. Comparative study of the effects of different chelating ligands on the absorption and transport of mercury in maize (Zea mays L.). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 188:109897. [PMID: 31704327 DOI: 10.1016/j.ecoenv.2019.109897] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) pollution seriously threatens food safety and has attracted global attention. Phytoextraction, due to its low cost, applicability, and environmental friendliness, is considered a new technology for clean-up of heavy metal contamination in the environment. However, the low bioavailability of Hg in polluted areas greatly limits the applicability of phytoextraction. Here, we compared the effects of six common chelating ligands on the absorption and transport of Hg in maize (Zea mays L.), which has a high biomass and short growth cycle. The results showed that the root length and biomass of maize seedlings of the groups treated with the six chelating ligands (EDTA, iodide, ammonium, thiosulfate, thiocyanate, and thiocarbamide) did not change compared with those of the non-treated groups. Co-exposure to Hg and each chelating ligand markedly alleviated the inhibitory effect induced by Hg. Iodide treatment resulted in the lowest root Hg content and highest translocation factor (TF) value, while ammonium treatment gave rise to the highest shoot Hg concentration and lowest TF. Compared with other chelating ligands, thiosulfate exhibited the maximum alleviation of Hg toxicity and achieved the highest concentration of Hg in the roots and aerial parts. Moreover, the TF and Hg accumulation in the thiosulfate and Hg co-exposed group were much higher than those in the group exposed to Hg alone. This finding suggests that, among these common chelating ligands, thiosulfate compounds have great potential for Hg phytoextraction, while the others can immobilize Hg in polluted areas.
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Affiliation(s)
- Yunyun Li
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jiaxun Guan
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China.
| | - Bai Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu-Feng Li
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
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16
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Novirsa R, Dinh QP, Jeong H, Addai-Arhin S, Nugraha WC, Hirota N, Wispriyono B, Ishibashi Y, Arizono K. The dietary intake of mercury from rice and human health risk in artisanal small-scale gold mining area, Indonesia. ACTA ACUST UNITED AC 2020. [DOI: 10.2131/fts.7.215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Randy Novirsa
- Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Quang Phan Dinh
- Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Huiho Jeong
- Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Sylvester Addai-Arhin
- Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Willy Cahya Nugraha
- Graduate School of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Nana Hirota
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Bambang Wispriyono
- Department of Environmental Health, Faculty of Public Health, University of Indonesia
| | - Yasuhiro Ishibashi
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Koji Arizono
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
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17
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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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18
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Sheng F, Ling J, Hong R, Jin X, Wang C, Zhong H, Gu X, Gu C. A new pathway of monomethylmercury photodegradation mediated by singlet oxygen on the interface of sediment soil and water. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 248:667-675. [PMID: 30849584 DOI: 10.1016/j.envpol.2019.02.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/31/2019] [Accepted: 02/15/2019] [Indexed: 06/09/2023]
Abstract
Photodegradation is an important pathway for monomethylmercury (MeHg) degradation in aquatic ecosystems. In this process, dissolved organic matter (DOM) plays an essential role. However, little information is available regarding the photo-transformation of MeHg in shallow aquatic environments, where a significant portion of MeHg is associated with soil suspensions. In this study, 14 soils sampled from different sites in China were used to simulate these conditions. Our results clearly demonstrated that soil organic matter (SOM) was the most important factor controlling the MeHg photodegradation in suspension. Degradation in this heterogeneous aqueous system was shown to be mediated by the 1O2 produced by organic matter on the surface of the soil particles rather than by DOM. This was confirmed by the strong correlation between the kinetics rate constant of MeHg degradation and steady state concentrations of 1O2 (R2 = 0.81). Our results propose a new pathway of MeHg induced by sediment soils under sunlight irradiation. Identification of this pathway may improve the estimates of potential ecological risk of Hg in shallow field ecosystems.
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Affiliation(s)
- Feng Sheng
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Jingyi Ling
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Ran Hong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Xin Jin
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Chao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Xueyuan Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China.
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19
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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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20
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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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21
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Wang Z, Sun T, Driscoll CT, Yin Y, Zhang X. Mechanism of Accumulation of Methylmercury in Rice ( Oryza sativa L.) in a Mercury Mining Area. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9749-9757. [PMID: 30129363 DOI: 10.1021/acs.est.8b01783] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Rice consumption is the primary pathway for methylmercury (MeHg) exposure at inland mercury (Hg) mining areas of China. The sources and processes of formation and translocation for MeHg in rice plant are complex and remain largely unknown. In this study, rice ( Oryza sativa L.) was exposed to isotopically labeled dimethylmercury (DMe199Hg) in field experiments using open top chambers to explore the response of MeHg accumulation in rice tissues to different levels of DMe199Hg in air. Rice leaves assimilated DMeHg from air, which was subsequently largely stored in aboveground tissues, including the rice grain, with only a small amount reaching the root. Combining these experimental results with field investigations of DMeHg concentrations in air beneath the rice canopy in a Hg mining area, we estimate that 15.5%, 10.8%, and 8.50% MeHg in the brown rice, the leaf, and the upper stalk, respectively, could be derived from atmospheric sources of DMeHg, while 99.5% of MeHg in rice root originated from the rice soil-water system. These findings help refine the mechanism of MeHg accumulation in rice that, in addition to soil, a fraction of MeHg in rice plants can be derived from DMeHg emissions from flooded rice paddies in Hg mining areas.
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Affiliation(s)
- Zhangwei Wang
- Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , No. 18 Shuangqing Road , Beijing 100085 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Ting Sun
- Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , No. 18 Shuangqing Road , Beijing 100085 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Charles T Driscoll
- Department of Civil and Environmental Engineering , Syracuse University , 151 Link Hall , Syracuse , New York 13244 , United States
| | - Yongguang Yin
- Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , No. 18 Shuangqing Road , Beijing 100085 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Xiaoshan Zhang
- Research Center for Eco-Environmental Sciences , Chinese Academy of Sciences , No. 18 Shuangqing Road , Beijing 100085 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
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22
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Qian X, Wu Y, Zhou H, Xu X, Xu Z, Shang L, Qiu G. Total mercury and methylmercury accumulation in wild plants grown at wastelands composed of mine tailings: Insights into potential candidates for phytoremediation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 239:757-767. [PMID: 29729617 DOI: 10.1016/j.envpol.2018.04.105] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 05/04/2023]
Abstract
Total mercury (THg) and methylmercury (MMHg) were investigated in 259 wild plants belonging to 49 species in 29 families that grew in heavily Hg-contaminated wastelands composed of cinnabar ore mine tailings (calcines) in the Wanshan region, southwestern China, the world's third largest Hg mining district. The bioconcentration factors (BCFs) of THg and MMHg from soil to roots ([THg]root/[THg]soil, [MMHg]root/[MMHg]soil) were evaluated. The results showed that THg and MMHg in both plants and soils varied widely, with ranges of 0.076-140 μg/g THg and 0.19-87 ng/g MMHg in roots, 0.19-106 μg/g THg and 0.06-31 ng/g MMHg in shoots, and 0.74-1440 μg/g THg and 0.41-820 ng/g MMHg in soil. Among all investigated species, Arthraxon hispidus, Eremochloa ciliaris, Clerodendrum bunge, and Ixeris sonchifolia had significantly elevated concentrations of THg in shoots and/or roots that reached 100 μg/g, whereas Chenopodium glaucum, Corydalisedulis maxim, and Rumex acetosa contained low values below 0.5 μg/g. In addition to the high THg concentrations, the fern E. ciliaris also showed high BCF values for both THg and MMHg exceeding 1.0, suggesting its capability to extract Hg from soils. Considering its dominance and the tolerance identified in the present study, E. ciliaris is suggested to be a practical candidate for phytoextraction, whereas A. hispidus is identified as a potential candidate for phytostabilization of Hg mining-contaminated soils.
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Affiliation(s)
- Xiaoli Qian
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550003, PR China
| | - Yonggui Wu
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550003, PR China
| | - Hongyun Zhou
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550003, PR China
| | - Xiaohang Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China
| | - Zhidong Xu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China
| | - Lihai Shang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China
| | - Guangle Qiu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, PR China.
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Zhang Y, Liu YR, Lei P, Wang YJ, Zhong H. Biochar and nitrate reduce risk of methylmercury in soils under straw amendment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 619-620:384-390. [PMID: 29156259 DOI: 10.1016/j.scitotenv.2017.11.106] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 06/07/2023]
Abstract
There is growing evidence that incorporating crop straw into soils, which is being widely encouraged in many parts of the world, could increase net methylmercury (MeHg) production in soils and MeHg accumulation in crops. We explored the possibility of mitigating the risk of increased MeHg levels under straw amendment by transforming straw into biochar (BC). Greenhouse and batch experiments were conducted, in which soil MeHg concentrations, MeHg phytoavailability and accumulation in rice, dynamics of sulfate, nitrate and abundances of sulfate reducing bacteria (SRB) were compared in 'Control' (Hg contaminated soil), 'Straw' (soil with 1% rice straw), 'Straw+BC' (soil with 1% straw and 1% biochar), and 'Straw+BC+N' (soil with 1% straw, 1% biochar and 0.12% nitrate). Our results indicate that straw amendment increased MeHg concentrations in soils (28-136% higher) and rice plants (26% higher in grains, 'Straw' versus 'Control'), while co-application of biochar with straw reduced grain MeHg levels (60% lower, 'Straw+BC' versus 'Straw'). This could be mainly attributed to the reduced MeHg availability to rice plants (phytoavailability, extraction rates of MeHg by ammonium thiosulfate) under biochar amendment (64-99% lower, 'Straw+BC' versus 'Straw'). However, biochar amendment enhanced soil MeHg levels (5-75% higher, 'Straw+BC' versus 'Control'). Interestingly, nitrate addition helped reduce soil MeHg concentrations (11-41% lower, 'Straw+BC+N' versus 'Straw+BC') by facilitating nitrate reduction while inhibiting SRB activities. Subsequently, addition of nitrate with biochar, compared with biochar alone, further reduced grain MeHg levels by 34%. Therefore, straw biochar together with nitrate could possibly be effective in mitigating the risk of MeHg under straw amendment. Furthermore, the results evidence the impacts of straw management on the risk posed by MeHg in soils and emphasize the necessity to carefully consider the straw management policy in Hg-contaminated areas.
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Affiliation(s)
- Yue Zhang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resources Reuse, Nanjing, Jiangsu Province, China
| | - Yu-Rong Liu
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Pei Lei
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yong-Jie Wang
- School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resources Reuse, Nanjing, Jiangsu Province, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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24
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Rodríguez L, Alonso-Azcárate J, Gómez R, Rodríguez-Castellanos L. Comparison of extractants used for the assessment of mercury availability in a soil from the Almadén mining district (Spain). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:12963-12970. [PMID: 28374201 DOI: 10.1007/s11356-017-8828-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/13/2017] [Indexed: 06/07/2023]
Abstract
Single extraction methods have been extensively used to assess the availability of metals in polluted soils. This work focused on checking the feasibility of several chemicals, i.e. CaCl2, EDTA, diethylenetriaminepentaacetic acid (DTPA) and a low-molecular-weight organic acid mixture (rhizosphere-based method), to be used as extractants for mercury (Hg) in a soil from the Almadén mining district (Spain). Moreover, the effect of several experimental parameters, i.e. extraction time (0.5, 1, 2, 5, 16 and 24 h), concentration of extractant (0.01, 0.05, 0.1 and 1 M) and soil/extractant ratio (1:2, 1:5 and 1:10), on the amount of Hg extracted was investigated. The Hg extraction ability followed the descending order EDTA > rhizosphere-based method > DTPA ≈ CaCl2. This ranking was attributed to the higher complexation power of EDTA and organic acids. It was also found that extraction times between 2 and 5 h are required to avoid underestimation of mobile Hg and re-adsorption of the Hg previously extracted. Although some exceptions were found, Hg extraction efficiency was generally enhanced with higher extractant concentrations. Finally, the amount of Hg extracted by the four extractants increased with decreasing soil/extractant ratios.
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Affiliation(s)
- Luis Rodríguez
- Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain.
| | - Jacinto Alonso-Azcárate
- Department of Physical Chemistry, Faculty of Environmental Sciences and Biochemistry, University of Castilla-La Mancha, Avenida Carlos III, s/n, 45071, Toledo, Spain
| | - Rocío Gómez
- Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain
| | - Laura Rodríguez-Castellanos
- Department of Chemical Engineering, School of Civil Engineering, University of Castilla-La Mancha, Avenida Camilo José Cela, s/n, 13071, Ciudad Real, Spain
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25
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Strickman RJ, Mitchell CPJ. Accumulation and translocation of methylmercury and inorganic mercury in Oryza sativa: An enriched isotope tracer study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 574:1415-1423. [PMID: 27542632 DOI: 10.1016/j.scitotenv.2016.08.068] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/08/2016] [Accepted: 08/09/2016] [Indexed: 06/06/2023]
Abstract
Methylmercury (MeHg) accumulation in rice is an emerging human health issue, but uptake pathways and translocation into the grain remain poorly understood. We grew Oryza sativa plants in pots of wetland soil amended with an enriched mercury isotope (94.3% 200Hg) tracer, alongside unvegetated control pots, and assessed both ambient and tracer MeHg and inorganic Hg (IHg) concentrations in soil and plant tissues at three growth stages. Based on similar ratios of ambient:tracer MeHg concentrations in soil and plant tissues, we provide the first direct evidence that MeHg is first synthesized in saturated soil and subsequently translocated to rice grains. There is no evidence of in planta methylation of IHg, but significant losses of MeHg from plant tissues between flowering and maturity indicates likely in planta demethylation. In this greenhouse experiment, lower percent of tracer MeHg in vegetated soils at late growth stages suggests that rice plants reduce the net MeHg accumulation capacity of soils, although the mechanism remains unclear. For IHg, roots accumulated Hg from the soil, straw from the soil and the atmosphere, and grain almost entirely from the atmosphere. Management strategies that aim to reduce MeHg accumulation in rice should focus on mercury methylation in paddy soils, but IHg reductions will depend on regional controls of atmospheric Hg.
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Affiliation(s)
- R J Strickman
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
| | - C P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada.
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26
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Chen R, Hu B, Liu Y, Xu J, Yang G, Xu D, Chen C. Beyond PM2.5: The role of ultrafine particles on adverse health effects of air pollution. Biochim Biophys Acta Gen Subj 2016; 1860:2844-55. [DOI: 10.1016/j.bbagen.2016.03.019] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/04/2016] [Accepted: 03/11/2016] [Indexed: 12/29/2022]
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27
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Shu R, Wang Y, Zhong H. Biochar amendment reduced methylmercury accumulation in rice plants. JOURNAL OF HAZARDOUS MATERIALS 2016; 313:1-8. [PMID: 27045620 DOI: 10.1016/j.jhazmat.2016.03.080] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/25/2016] [Accepted: 03/28/2016] [Indexed: 06/05/2023]
Abstract
There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1-4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49-92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35-79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment.
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Affiliation(s)
- Rui Shu
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People's Republic of China, People's Republic of China
| | - Yongjie Wang
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People's Republic of China, People's Republic of China
| | - Huan Zhong
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People's Republic of China, People's Republic of China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
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28
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Johnson NW, Mitchell CPJ, Engstrom DR, Bailey LT, Coleman Wasik JK, Berndt ME. Methylmercury production in a chronically sulfate-impacted sub-boreal wetland. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2016; 18:725-734. [PMID: 27224550 DOI: 10.1039/c6em00138f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Increased deposition of atmospheric sulfate exacerbates methylmercury (MeHg) production in freshwater wetlands by stimulating methylating bacteria, but it is unclear how methylation in sub-boreal wetlands is impacted by chronically elevated sulfate inputs, such as through mine discharges. The purpose of our study is to determine how sulfate discharges to wetlands from iron mining activities impact MeHg production. In this study, we compare spatial and temporal patterns in MeHg and associated geochemistry in two wetlands receiving contrasting loads of sulfate. Two orders of magnitude less sulfate in the un-impacted wetland create significant differences in acid-volatile sulfide and porewater sulfide; however, dissolved and solid-phase MeHg concentrations and methylation rate potentials (Kmeth) are statistically similar in both wetlands. Permitted mine pumping events flood the sulfate-impacted wetland with very high sulfate waters during the fall. In contrast to observations in sulfate-limited systems, this large input of sulfate to a chronically sulfate-impacted system led to significantly lower potential relative methylation rates, suggesting a predominance of demethylation processes over methylation processes during the sulfate loading. Overall, short-term measurements of methylation and demethylation potential are unrelated to gross measures of long-term MeHg accumulation, indicating a decoupling of short- and long-term process measurements and an overall disequilibrium in the systems. High sulfide accumulation, above ∼600-800 μg l(-1) sulfide, in the sulfate-impacted system lowers long-term MeHg accumulation, perhaps as a result of less bioavailable Hg-S complexes. Although continued research is required to determine how sulfate-limited freshwater wetlands might respond to new, large inputs of high-sulfate runoff from mining operations, chronically impacted wetlands do not appear to continually accumulate or produce MeHg at rates different from wetlands unimpacted by mining.
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Affiliation(s)
- Nathan W Johnson
- Department of Civil Engineering, University of Minnesota Duluth, USA.
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29
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Zhu H, Zhong H, Wu J. Incorporating rice residues into paddy soils affects methylmercury accumulation in rice. CHEMOSPHERE 2016; 152:259-264. [PMID: 26974480 DOI: 10.1016/j.chemosphere.2016.02.095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 02/17/2016] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Paddy fields are characterized by frequent organic input (e.g., fertilization and rice residue amendment), which may affect mercury biogeochemistry and bioaccumulation. To explore potential effects of rice residue amendment on methylmercury (MMHg) accumulation in rice, a mercury-contaminated paddy soil was amended with rice root (RR), rice straw (RS) or composted rice straw (CS), and planted with rice. Incorporating RS or CS increased grain MMHg concentration by 14% or 11%. The observed increases could be attributed to the elevated porewater MMHg levels and thus enhanced MMHg uptake by plants, as well as increased MMHg translocation to grain within plants. Our results indicated for the first time that rice residue amendment could significantly affect MMHg accumulation in rice grain, which should be considered in risk assessment of MMHg in contaminated areas.
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Affiliation(s)
- Huike Zhu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, People's Republic of China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, People's Republic of China; Environmental and Life Sciences Program (ENLS), Trent University, Peterborough, Ontario, Canada.
| | - Jialu Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, People's Republic of China.
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30
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Shu R, Dang F, Zhong H. Effects of incorporating differently-treated rice straw on phytoavailability of methylmercury in soil. CHEMOSPHERE 2016; 145:457-463. [PMID: 26694796 DOI: 10.1016/j.chemosphere.2015.11.037] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 11/01/2015] [Accepted: 11/12/2015] [Indexed: 06/05/2023]
Abstract
Differently-treated crops straw is being widely used to fertilize soil, while the potential impacts of straw amendment on the biogeochemistry and phytoavailability of mercury in contaminated soils are largely unknown. In the present study, differently-treated rice straw (dry straw, composted straw, straw biochar, and straw ash) was incorporated into mercury-contaminated soil at an environment relevant level (1/100, w/w), and mercury speciation, methylmercury (MeHg) phytoavailability (using ammonium thiosulfate extraction method, validated elsewhere) and bioaccumulation (in Indian mustard Brassica junceas) were quantified. Our results indicated that incorporating straw biochar or composted straw into soil would decrease phytoavailable MeHg levels, possibly due to the strong binding of MeHg with particulate organic matter in amended straw ('MeHg immobilization effect'). Consequently, MeHg accumulation in aboveground tissue of Indian mustard harvested from straw biochar-amended soil decreased by 20% compared to the control. Differently, incorporation of dry straw resulted in elevated MeHg levels in soil ('Mercury methylation effect'). Decomposition of amended dry straw in soil would evidently increase DOC levels (averagely 40%-195% higher than the control), which may subsequently mobilize MeHg in the soil ('MeHg mobilization effect'). Accordingly, incorporation of dry straw led to increased phytoavailable MeHg levels in the soil and doubled MeHg accumulation in Indian mustard. Our results provided the first evidence that incorporating differently-treated rice straw into soil could have diverse effects on mercury biogeochemistry and phytoavailability, which should be taken into account in risk assessment or soil remediation.
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Affiliation(s)
- Rui Shu
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People's Republic of China.
| | - Fei Dang
- State Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province, People's Republic of China.
| | - Huan Zhong
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, People's Republic of China.
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31
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Zhu H, Zhong H, Evans D, Hintelmann H. Effects of rice residue incorporation on the speciation, potential bioavailability and risk of mercury in a contaminated paddy soil. JOURNAL OF HAZARDOUS MATERIALS 2015; 293:64-71. [PMID: 25827269 DOI: 10.1016/j.jhazmat.2015.03.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 03/03/2015] [Accepted: 03/14/2015] [Indexed: 06/04/2023]
Abstract
To reduce air pollution, straw return instead of burning is being strongly encouraged in China, including some mercury polluted areas. Nevertheless, the possible influences of straw return on methylation, bioavailability and exposure risk of mercury were relatively unknown. In this study, different amounts of rice straw or root were added into a mercury contaminated soil. Potential bioavailability of soil-bound mercury to crops/deposit-feeders was assessed by quantifying extraction rates of mercury (%) by calcium chloride (CaCl2)/bovine serum albumin (BSA). Extraction rates of inorganic mercury (IHg) or methylmercury (MMHg) decreased significantly in rice residue amended soils, possibly due to the strong binding of mercury with organic matter in root/straw. Meanwhile, MMHg concentrations increased by 2-8 times in amended soils. Such increases were attributed to enhanced microbial activities and/or formation of Hg-S-DOM complexes after rice residue incorporation and decomposition. Consequently, potential exposure risk of IHg (quantified as concentration of potentially bioavailable mercury in soil) decreased significantly while that of MMHg increased up to 4 times. To our knowledge, this is the first study demonstrating that rice residue incorporation could significantly affect biogeochemistry of both IHg and MMHg in soils, which should be considered in straw incorporation activities in mercury polluted areas.
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Affiliation(s)
- Huike Zhu
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, PR China
| | - Huan Zhong
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, PR China.
| | - Douglas Evans
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, PR China; Environmental and Resource Studies Program, Trent University, Peterborough, Ontario, Canada
| | - Holger Hintelmann
- Department of Chemistry, Trent University, Peterborough, Ontario, Canada
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