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Liu J, Wang J, Ning Y, Yang S, Wang P, Shaheen SM, Feng X, Rinklebe J. Methylmercury production in a paddy soil and its uptake by rice plants as affected by different geochemical mercury pools. Environ Int 2019; 129:461-469. [PMID: 31154148 DOI: 10.1016/j.envint.2019.04.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/15/2019] [Accepted: 04/28/2019] [Indexed: 06/09/2023]
Abstract
The formation of neurotoxic methylmercury (MeHg) in paddy fields and its accumulation by rice plants is of high environmental concern. The contribution of different geochemical mercury (Hg) pools in paddy soils to MeHg production and its accumulation by rice seedlings is not well-studied up to now. Therefore, we investigated the impact of different inorganic Hg forms, including HgCl2, nano-particulated HgS (nano-HgS), Hg bound with dissolved organic matter (Hg-DOM), β-HgS, and α-HgS, at levels of 5 mg Hg/kg soil and 50 mg Hg/kg soil, on the production of MeHg in the soil during rice growing season. Further, we studied the uptake of MeHg by the roots, stalks, leaves, and grains of rice in the tillering, panicle formation, and ripening growth stages, and compared these treatments to a non-polluted soil (control). MeHg contents in HgCl2 polluted soil were the highest, and were 13.5 times and 36.1 times higher than control in 5 and 50 mg/kg Hg treatments, respectively. MeHg contents in α-HgS, β-HgS, nano-HgS, and Hg-DOM polluted soil were 3.9, 2.6, 2.4, and 1.7 times, and 4.4, 15.1, 6.7, and 10.9 times higher than control in 5 and 50 mg/kg Hg treatments, respectively, suggesting the mobilization and methylation of these Hg complexes. The ratio of MeHg to total Hg in the pore water (indication of methylation potential) in HgCl2 and β-HgS treatments were higher than in Hg-DOM, α-HgS, and nano-HgS treatments. HgCl2 treatment resulted in significantly higher MeHg contents in the root, stalk, leaf, and brown rice than nano-HgS, Hg-DOM, β-HgS, and α-HgS treatments both in 5 and 50 mg/kg Hg polluted soils. Rice grain in HgCl2 treatment showed a potential hazard to human health, as indicated by high health risk index (HRI > 1) of MeHg. Current results improve our understanding of MeHg production in soil polluted with different Hg forms, and the assessment of human health risks from consumption of MeHg-laden rice grain at Hg polluted sites with different Hg forms in soils.
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Affiliation(s)
- Jinling Liu
- School of Earth Sciences, China University of Geosciences, Wuhan 430074, China.
| | - Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China.
| | - Yongqiang Ning
- School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Shaochen Yang
- School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Pengcong Wang
- School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Sabry M Shaheen
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; King Abdulaziz University, Faculty of Meteorology, Environment, and Arid Land Agriculture, Department of Arid Land Agriculture, 21589 Jeddah, Saudi Arabia; University of Kafrelsheikh, Faculty of Agriculture, Department of Soil and Water Sciences, 33516 Kafr El-Sheikh, Egypt.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; University of Sejong, Department of Environment, Energy and Geoinformatics, 98 Gunja-Dong, Guangjin-Gu, Seoul, South Korea.
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