Department of Life Sciences, National Central University, Chung-Li, Taiwan.
Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan.
Chemosphere. 2018 Jun;200:266-273. doi: 10.1016/j.chemosphere.2018.02.085. Epub 2018 Feb 15.
Utilization of bacterial volatilization can be problematic to remediate mercury (Hg)-contaminated soils because most of the Hg in soils is bound to soil particles. The objective of this study was to develop a two-stage system (chemical extraction followed by microbial reduction) for Hg-contaminated soil remediation. The tasks were to (1) select the extraction reagents for Hg extraction, (2) assess the effects of extraction reagents on the growth of Hg-reducing bacterial strains, and (3) evaluate the effectiveness of Ca and Mg addition on merA gene (Hg reductase) induction. Bacterial inhibition was observed with the addition of 0.1 M ethylenediaminetetraacetic acid or citric acid. Up to 65% of Hg was biotransformed (Hg concentration = 69 mg/kg) from the soils after a 24 h extraction using 0.5 M ammonium thiosulfate. Ca and Mg were selected because they have the same electric charge as Hg and the studied groundwater contained high concentrations of Ca and Mg. Results showed that the addition of 200 mg/L Ca or 650 mg/L Mg could reach effective merA induction. In the two-stage experiment, 120 mg/kg Hg-contaminated soils were extracted with 2 rounds of extraction processes for 10 h using 0.5 M ammonium thiosulfate. Approximately 77% of Hg was extracted from the soils after the first-step extraction process. Up to 81% of Hg was transformed from the washing solution via the biotransformation processes with Enterobacter cloacae addition and Ca and Mg supplementation. The two-stage remedial system has the potential to be developed into a practical technology to remediate Hg-contaminated sites.
利用细菌挥发作用来修复受汞（Hg）污染的土壤可能会出现问题，因为土壤中的大部分 Hg 都与土壤颗粒结合在一起。本研究的目的是开发一种两阶段系统（化学萃取后进行微生物还原）来修复受 Hg 污染的土壤。任务包括：（1）选择萃取试剂来萃取 Hg；（2）评估萃取试剂对 Hg 还原菌生长的影响；（3）评估添加 Ca 和 Mg 对 merA 基因（Hg 还原酶）诱导的有效性。添加 0.1 M 乙二胺四乙酸或柠檬酸会观察到细菌抑制作用。使用 0.5 M 硫代硫酸铵进行 24 小时萃取后，可将土壤中 65%的 Hg 转化为生物形态（Hg 浓度= 69 mg/kg）。选择 Ca 和 Mg 是因为它们与 Hg 具有相同的电荷，且研究中的地下水含有高浓度的 Ca 和 Mg。结果表明，添加 200 mg/L Ca 或 650 mg/L Mg 可达到有效的 merA 诱导效果。在两阶段实验中，使用 2 轮 0.5 M 硫代硫酸铵萃取过程，对 120 mg/kg Hg 污染的土壤进行 10 小时的萃取。第一轮萃取过程后，可从土壤中提取出 77%的 Hg。通过添加 Enterobacter cloacae 和补充 Ca 和 Mg 进行生物转化过程，可将洗涤液中的 81% Hg 转化。两阶段修复系统具有开发成实际的 Hg 污染场地修复技术的潜力。
