The water-level fluctuation zone(WLFZ)has been considered as a hotspot for mercury(Hg)methylation.Flooding-tolerant herbs are gradually acclimated to this water-land eco-tone,tending to form substantial root systems for improving erosion resistance.Accom-panying rhizosphere microzone plays crucial but unclear roles in methylmercury(MeHg)formation in the WLFZ.Thus,we conducted this study in the WLFZ of the Three Gorges Reservoir,to explore effects of the rhizosphere of a dominant flooding-tolerant herb(bermudagrass)on MeHg production.The elevated Hg and MeHg in rhizosphere soils suggest that the rhizosphere environment provides favorable conditions for Hg accu-mulation and methylation.The increased bioavailable Hg and microbial activity in the rhizosphere probably serve as important factors driving MeHg formation in the pres-ence of bermudagrass.Simultaneously,the rhizosphere environments changed the rich-ness,diversity,and distribution of hgcA-containing microorganisms.Here,a typical iron-reducing bacterium(Geobacteraceae)has been screened,however,the majority of hgcA genes detected in rhizosphere,near-,and non-rhizosphere soils of the WLFZ were un-classified.Collectively,these results provide new insights into the elevated MeHg pro-duction as related to microbial processes in the rhizosphere of perennial herbs in the WLFZ,with general implications for Hg cycling in other ecosystems with water-level fluctuations.

Juan Wang;Yuping Xiang;Xiaosong Tian;Cheng Zhang;Guiqing Gong;Jinping Xue;Tao Jiang;Dingyong Wang;Yongmin Wang

Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin,College of Resources and Environment,Southwest University,Chongqing 400715,China;Laboratory of Environmental Nanotechnology&Health Effect,Chinese Academy of Sciences,Research Center for Eco-Environmental Sciences,Beijing 100085,China;College of Resources and Safety,Chongqing Vocational Institute of Engineering,Chongqing 402260,China;Institut des Sciences Analytiques et des Physico-Chimie pour l'Environnement et les Matériaux(IPREM),UMR 5254,CNRS,Université de Pau et des Pays de l'Adour,Pau 64000,France

环境科学学报（英文版）

[1]Juan Wang;Yuping Xiang;Xiaosong Tian;Cheng Zhang;Guiqing Gong;Jinping Xue;Tao Jiang;Dingyong Wang;Yongmin Wang-.Role of the rhizosphere of a flooding-tolerant herb in promoting mercury methylation in water-level fluctuation zones)[J].环境科学学报（英文版）,2022(09):139-151

WLFZ,Accom,panying,microzone,bermudagrass,hgcA,Geobacteraceae

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