Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, Qingdao 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China.
J Environ Sci (China). 2018 Jun;68:177-184. doi: 10.1016/j.jes.2018.02.017. Epub 2018 Mar 8.
Mercury (Hg) is among the most concerned contaminants in the world. It has three major chemical forms in the environment, including Hg, Hg, and methylmercury (MeHg). Due to their differences in toxicity, mobility, and bioavailability, speciation analysis is critical for understanding Hg cycling and fate in the environment. SnCl reduction-atomic fluorescence spectrometry detection is the most commonly used method for analyzing inorganic Hg. However, it should be noted that MeHg may also be reduced by SnCl, which would result in the overestimation of inorganic Hg. In this study, the reduction of MeHg by SnCl in both de-ionized (DI) water and four natural waters was investigated. The results showed that MeHg could be reduced by SnCl in DI water whereas this reaction was hard to occur in tested natural waters. By investigating the effects of water chemical characteristics (dissolved organic matter, pH and common anions and cations) on this reaction, SO was identified to be the dominant factor prohibiting SnCl induced MeHg reduction in natural waters. SO in natural waters was evidenced to be reduced to S by SnCl and the generated S can complex with MeHg to form MeHgS which is hard to be reduced by SnCl. Findings of this study indicate that the effect of MeHg reduction by SnCl on inorganic Hg analysis is negligible in natural waters; however, at simulated experimental systems without SO, SO should be added as protecting agents to prevent MeHg reduction when analyzing inorganic Hg if it would not cause any other unwanted effects.
汞（Hg）是世界上最受关注的污染物之一。它在环境中有三种主要的化学形态，包括元素汞（Hg）、二价汞（Hg）和甲基汞（MeHg）。由于它们在毒性、迁移性和生物利用度方面存在差异，因此形态分析对于了解汞在环境中的循环和归宿至关重要。SnCl 还原-原子荧光光谱法检测是分析无机汞最常用的方法。然而，应该注意的是，MeHg 也可能被 SnCl 还原，这会导致无机汞的高估。在本研究中，研究了 SnCl 在去离子水（DI）和四种天然水中对 MeHg 的还原作用。结果表明，MeHg 可以在 DI 水中被 SnCl 还原，但在测试的天然水中，这种反应很难发生。通过研究水化学特性（溶解有机物、pH 值和常见阴离子和阳离子）对该反应的影响，发现 SO 是阻止 SnCl 诱导天然水中 MeHg 还原的主要因素。SO 在天然水中被 SnCl 还原为 S，生成的 S 可以与 MeHg 形成 MeHgS，而 MeHgS 难以被 SnCl 还原。本研究结果表明，在天然水中，SnCl 还原 MeHg 对无机汞分析的影响可以忽略不计；然而，在没有 SO 的模拟实验系统中，如果 SO 不会引起任何其他不良影响，则应添加 SO 作为保护剂，以防止在分析无机汞时 MeHg 被还原。
