Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Sci Total Environ. 2022 May 1;819:152047. doi: 10.1016/j.scitotenv.2021.152047. Epub 2021 Nov 29.
Mercuric Hg ion forms strong complexes with dissolved organic matter (DOM) in natural waters. The complexation of Hg by sulfhydryl groups of DOM was regarded as the main mechanism for Hg-DOM interactions, particularly in anoxic sulfur and DOM-rich environments. In the present study, the influences of pH and sulfide addition on the molecular structure of Hg-DOM complexes and the characteristics of Hg binding to DOM were investigated using FT-IR and synchronous fluorescence two-dimensional correlation spectroscopic analysis. Results showed that, during the Hg binding process, the aromatic hydrogen CH in humic acids (HA) gave the fastest responses to pH perturbation and the S-reacted HA (S-HA) exhibited different reaction patterns from the unreacted HA. In S-HA, the esters/alcohols CO and carboxyl CO gave the fastest responses to Hg binding. In the process of S-HA binding to Hg, the protein-like fractions including proteins, amino acids or monoaromatics played the leading role. Sulfide addition of HA enhanced the reactivity of small molecular weight compounds with low aromaticity and improved the binding ability of protein-like fractions to Hg. These findings provide a better understanding of the interaction mechanisms between Hg and DOM at a molecular level and have important environmental implications in Hg biogeochemical transformation, transport and cycling.
汞离子（Hg2+）在天然水中与溶解态有机物（DOM）形成强配合物。巯基与 DOM 的配合被认为是 Hg-DOM 相互作用的主要机制，特别是在缺氧硫和 DOM 丰富的环境中。本研究采用傅里叶变换红外光谱（FT-IR）和同步荧光二维相关光谱分析技术，研究了 pH 值和硫化物添加对 Hg-DOM 配合物分子结构以及 Hg 与 DOM 结合特性的影响。结果表明，在 Hg 结合过程中，腐殖酸（HA）中的芳香氢 CH 对 pH 扰动的响应最快，而未反应的 HA 和反应后的 HA（S-HA）表现出不同的反应模式。在 S-HA 中，酯/醇 CO 和羧基 CO 对 Hg 结合的响应最快。在 S-HA 与 Hg 结合的过程中，起主导作用的是包含蛋白质、氨基酸或单环芳烃的类蛋白质部分。HA 中添加硫化物增强了低芳香性小分子化合物的反应活性，提高了类蛋白质部分与 Hg 的结合能力。这些发现为深入了解 Hg 与 DOM 在分子水平上的相互作用机制提供了更好的认识，对 Hg 生物地球化学转化、传输和循环具有重要的环境意义。
