Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, Qingdao 266100, China.
J Hazard Mater. 2016 Nov 5;317:466-475. doi: 10.1016/j.jhazmat.2016.05.084. Epub 2016 Jun 2.
Cinnabar dissolution is an important factor controlling mercury (Hg) cycling. Recent studies have suggested the co-occurrence of re-adsorption of the released Hg during the course of cinnabar dissolution. However, there is a lack of feasible techniques that can quantitatively assess the amount of Hg re-adsorbed on cinnabar when investigating cinnabar dissolution. In this study, a new method, based on isotope tracing and dilution techniques, was developed to study the role of Hg re-adsorption in cinnabar dissolution. The developed method includes two key components: (1) accurate measurement of both released and spiked Hg in aqueous phase and (2) estimation of re-adsorbed Hg on cinnabar surface via the reduction in spiked (202)Hg(2+). By adopting the developed method, it was found that the released Hg for trials purged with oxygen could reach several hundred μgL(-1), while no significant cinnabar dissolution was detected under anaerobic condition. Cinnabar dissolution rate when considering Hg re-adsorption was approximately 2 times the value calculated solely with the Hg detected in the aqueous phase. These results suggest that ignoring the Hg re-adsorption process can significantly underestimate the importance of cinnabar dissolution, highlighting the necessity of applying the developed method in future cinnabar dissolution studies.
辰砂溶解是控制汞（Hg）循环的一个重要因素。最近的研究表明，在辰砂溶解过程中，释放的 Hg 会发生再吸附。然而，在研究辰砂溶解时，缺乏能够定量评估辰砂上再吸附 Hg 量的可行技术。在这项研究中，开发了一种基于同位素示踪和稀释技术的新方法，以研究 Hg 再吸附在辰砂溶解中的作用。该方法包括两个关键组成部分：（1）准确测量水相中释放和添加的 Hg；（2）通过减少添加的（202）Hg（2+）来估计辰砂表面上的再吸附 Hg。采用所开发的方法发现，在充氧条件下进行的实验中，释放的 Hg 可达数百 μgL（-1），而在厌氧条件下则未检测到明显的辰砂溶解。考虑 Hg 再吸附时的辰砂溶解速率约为仅用水相中检测到的 Hg 计算得到的溶解速率的 2 倍。这些结果表明，忽略 Hg 再吸附过程会显著低估辰砂溶解的重要性，强调在未来的辰砂溶解研究中应用所开发方法的必要性。
