Vudamala Krushna, Chakraborty Parthasarathi, Sailaja Budati Bala Venkata
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004, India.
Department of Inorganic & Analytical Chemistry, Andhra University, Visakhapatnam, Andhra Pradesh, India.
Environ Sci Pollut Res Int. 2017 Jun;24(16):14499-14507. doi: 10.1007/s11356-017-8979-4. Epub 2017 Apr 27.
Mercury (Hg) reduction by humic substances (HS) in the aquatic medium under the dark condition is a poorly understood but important process in Hg biogeochemical cycling. In this study, an effort was made to provide a better understanding of Hg(II) reduction by well-characterized humic substances under dark condition. Reduction of Hg(II) by dissolved HS in aquatic systems increases with increasing Hg loading. However, Hg(II) reduction gradually decreases with the increasing total S content and oxygen containing functional groups in the dissolved HS under dark condition. Increasing major cation concentration decreases the rate of Hg(II) reduction in aquatic systems. High concentration of Ca ion slows down the intermolecular electron transfer from HS to Hg(II) and inhibits the formation of Hg in absence of light. This study indicates that complexation of Hg(II) and HS is essential for Hg reduction under dark condition.
在黑暗条件下，腐殖质（HS）在水介质中还原汞（Hg）是汞生物地球化学循环中一个尚未被充分理解但很重要的过程。在本研究中，我们致力于更好地理解在黑暗条件下，特性明确的腐殖质对汞（II）的还原作用。水生系统中溶解态腐殖质对汞（II）的还原作用随汞负荷的增加而增强。然而，在黑暗条件下，随着溶解态腐殖质中总硫含量和含氧官能团的增加，汞（II）的还原作用逐渐减弱。主要阳离子浓度的增加会降低水生系统中汞（II）的还原速率。高浓度的钙离子会减缓腐殖质向汞（II）的分子间电子转移，并在无光条件下抑制汞的形成。本研究表明，汞（II）与腐殖质的络合对于黑暗条件下的汞还原至关重要。
