Rice hull biochar enhances the mobilization and methylation of mercury in a soil under changing redox conditions: Implication for Hg risks management in paddy fields

Ying Xing; Jianxu Wang; Christoph E.S. Kinder; Xing Yang; Michal Slaný; Bing Wang; Hocheol Song; Sabry M. Shaheen; Peter Leinweber; Jörg Rinklebe

Environment International (Oct 2022)

Rice hull biochar enhances the mobilization and methylation of mercury in a soil under changing redox conditions: Implication for Hg risks management in paddy fields

Ying Xing,
Jianxu Wang,
Christoph E.S. Kinder,
Xing Yang,
Michal Slaný,
Bing Wang,
Hocheol Song,
Sabry M. Shaheen,
Peter Leinweber,
Jörg Rinklebe

Affiliations

Ying Xing: School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550002, PR 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
Jianxu Wang: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550082, PR 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
Christoph E.S. Kinder: 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
Xing Yang: 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
Michal Slaný: Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava, Slovakia
Bing Wang: College of Resources and Environment Engineering, Guizhou University, Guiyang, Guizhou 550025, PR China
Hocheol Song: University of Sejong, Department of Environment, Energy and Geoinformatics, 98 Gunja-Dong, Guangjin-Gu, Seoul, South Korea
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, Jeddah 21589, Saudi Arabia
Peter Leinweber: School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550002, PR 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; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550082, PR China; Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava, Slovakia; College of Resources and Environment Engineering, Guizhou University, Guiyang, Guizhou 550025, PR China; University of Sejong, Department of Environment, Energy and Geoinformatics, 98 Gunja-Dong, Guangjin-Gu, Seoul, South Korea; King Abdulaziz University, Faculty of Meteorology, Environment and Arid Land Agriculture, Department of Arid Land Agriculture, Jeddah 21589, Saudi Arabia; University of Kafrelsheikh, Faculty of Agriculture, Department of Soil and Water Sciences, 33516 Kafr El-Sheikh, Egypt; University of Rostock, Department Light, Life and Matter (LLM), Albert-Einstein-Strasse 25, D-18059 Rostock, Germany; Soil Science, University of Rostock, Justus-von-Liebig-Weg 6, 18051 Rostock, Germany
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; Corresponding author at: 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.

Journal volume & issue: Vol. 168
p. 107484

Abstract

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Biochar amendment to paddy soils was promising to mitigate mercury (Hg) accumulation in rice; thus, it was applied to reduce human Hg exposure via rice consumption. However, how biochar affects Hg mobilization and MeHg formation in soil under changed redox potential (Eh) conditions remained unknown. Here, we explored the change of dissolved total Hg (DTHg) and dissolved MeHg (DMeHg), and their controlling biogeochemical factors in a soil with(out) biochar amendment under changing Eh conditions using biogeochemical microcosm. Biochar amendment resulted in a widen Eh range (−300 to 400 mV) compared to the control (−250 to 350 mV), demonstrating that biochar promoted reduction-oxidization reactions in soil. Biochar amendment enhanced Hg mobilization by mediating reductive dissolution of Fe/Mn (hydr)oxides. Thus, the increased Hg availability promoted MeHg formation in the soils. Biochar amendment changed the soil organic matter (SOM) composition. Positive correlations between the relative abundance of LIPID (lipids, alkanes/alkenes), ALKYL (alkylaromatics), and suberin and MeHg concentrations indicate that these SOM groups might be related to MeHg formation. Biochar enhanced the releasing and methylation of Hg by promoting the mobilization of Fe(oxyhydr)oxides and alternation of carbon chemistry under dynamic Eh conditions. There is an unexpected environmental risk associated with biochar application to paddy soils under dynamic Eh condition, and one should be aware this risk when applying biochar aiming to minimize human Hg exposure health risks via rice consumption.

Published in Environment International

ISSN: 0160-4120 (Print)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Geography. Anthropology. Recreation: Environmental sciences
Website: https://www.journals.elsevier.com/environment-international

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