Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area
Mechanism of Accumulation of Methylmercury in Rice (Oryza sativa L.) in a Mercury Mining Area
复制标题
汞矿区水稻(Oryza sativa L.)甲基汞富集机理
DOI：
10.1021/acs.est.8b01783
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发表时间：
2018
影响因子：
11.4
通讯作者：
Xiaoshan Zhang
中科院分区：
文献类型：
--
作者：
Zhangwei Wang;Ting Sun;Charles T. Driscoll;Yongguang Yin;Xiaoshan Zhang
大米消费是中国内陆汞矿区甲基汞暴露的主要途径。甲基汞在水稻植株中的形成和运转的来源和过程是复杂的，并且在很大程度上仍不清楚。在本研究中，水稻(Oryza sativa L.)在田间试验中，利用开顶式密封箱研究了水稻组织中甲基汞积累对空气中不同浓度二甲基汞的响应。水稻叶片从空气中吸收二甲基汞，随后大部分储存在地上组织中，包括水稻籽粒，只有少量到达根部。结合对某汞矿区水稻冠层下空气中二甲基汞浓度的现场调查，我们估计水稻糙米、叶和上部茎中的甲基汞分别有15.5%、10.8%和8.50%来自大气来源的二甲基汞，而水稻根中99.5%的甲基汞来自水稻土壤-水系统。这些发现有助于完善甲基汞在水稻中积累的机制，即除了土壤之外，水稻植株中的一小部分甲基汞可以来自汞矿区被淹的稻田排放的二甲基汞。
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 sativaL.) 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.