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Increased Methylmercury Accumulation in Rice after Straw Amendment TEXT SIZE: A A A
Consumption of rice has been shown to be an important route of dietary exposure to methylmercury (MeHg, a neurotoxin) for Asians having a low fish but high rice diet. Therefore, factors that increase MeHg production and bioaccumulation in soil-rice systems, could enhance the risk of MeHg exposure. On the basis of a national-scale survey in China (64 sites in 12 provinces) and rice cultivation experiments, we report that straw amendment, a globally prevalent farming practice, could increase MeHg concentrations in paddy soils (11-1043%) and rice grains (95%). By carrying out a series of batch incubation, seedling uptake and sand culture experiments, we demonstrate that these increases could be attributed to (1) enhanced abundances/activities of microbial methylators and the transformation of refractory HgS to organic matter-complexed Hg, facilitating microbial Hg methylation in soils; (2) enhanced MeHg mobility, and increased root lengths (35-41%) and tip numbers (60-105%), increasing MeHg uptake by rice roots; and (3) enhanced MeHg translocation to rice grains from other tissues. Results of this study emphasize fresh organic matter-enhanced MeHg production and bioaccumulation, and highlight the increased risk of MeHg after straw amendment and thus the need for new policies concerning straw management.

Publication name

 ENVIRONMENTAL SCIENCE & TECHNOLOGY, 53 (11):6144-6153; 10.1021/acs.est.8b07145 JUN 4 2019

Author(s)

 Tang, Wenli; Hintelmann, Holger; Gu, Baohua; Feng, Xinbin; Liu, Yurong; Gao, Yuxi; Zhao, Jiating; Zhu, Huike; Lei, Pei; Zhong, Huan

Corresponding author(s) 

 ZHONG Huan 
 zhonghuan@nju.edu.cn  
 Nanjing Univ, Sch Environm, State Key Lab Pollut Control & Resource Reuse, Nanjing 210023, Jiangsu, Peoples R China.
 Trent Univ, Environm & Life Sci Program EnLS, Peterborough, ON K9L 0G2, Canada.

Author(s) from IGCAS   FENG Xinbin

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