Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich , CHN, CH-8092 Zurich, Switzerland.
Environ Sci Technol. 2013 Jul 16;47(14):7739-46. doi: 10.1021/es4010976. Epub 2013 Jul 2.
Mercury is a highly toxic priority pollutant that can be released from wetlands as a result of biogeochemical redox processes. To investigate the temperature-dependent release of colloidal and dissolved Hg induced by flooding of a contaminated riparian soil, we performed laboratory microcosm experiments at 5, 14, and 23 °C. Our results demonstrate substantial colloidal Hg mobilization concomitant with Cu prior to the main period of sulfate reduction. For Cu, we previously showed that this mobilization was due to biomineralization of metallic Cu nanoparticles associated with suspended bacteria. X-ray absorption spectroscopy at the Hg LIII-edge showed that colloidal Hg corresponded to Hg substituting for Cu in the metallic Cu nanoparticles. Over the course of microbial sulfate reduction, colloidal Hg concentrations decreased but continued to dominate total Hg in the pore water for up to 5 weeks of flooding at all temperatures. Transmission electron microscopy (TEM) suggested that Hg became associated with Cu-rich mixed metal sulfide nanoparticles. The formation of Hg-containing metallic Cu and metal sulfide nanoparticles in contaminated riparian soils may influence the availability of Hg for methylation or volatilization processes and has substantial potential to drive Hg release into adjacent water bodies.
汞是一种剧毒优先污染物，由于生物地球化学氧化还原过程，它可能会从湿地中释放出来。为了研究受污染河岸土壤淹水引发的胶体和溶解态汞的温度依赖性释放，我们在 5、14 和 23°C 下进行了实验室微宇宙实验。我们的结果表明，在硫酸盐还原的主要阶段之前，伴随着大量胶体汞和铜的释放。对于铜，我们之前表明，这种释放是由于与悬浮细菌相关的金属铜纳米粒子的生物矿化。汞 LIII 边的 X 射线吸收光谱表明，胶体汞对应于汞取代金属铜纳米粒子中的铜。在微生物硫酸盐还原过程中，胶体汞的浓度下降，但在所有温度下淹水长达 5 周的时间里，胶体汞仍继续主导孔隙水中的总汞。透射电子显微镜（TEM）表明，汞与富含铜的混合金属硫化物纳米颗粒结合。受污染河岸土壤中含汞的金属铜和金属硫化物纳米颗粒的形成可能会影响汞用于甲基化或挥发过程的可用性，并具有将汞释放到相邻水体中的巨大潜力。
