Ma Lan, Zhong Huan, Wu Yong-Gui
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing, Jiangsu, People's Republic of China.
Bull Environ Contam Toxicol. 2015 Mar;94(3):399-406. doi: 10.1007/s00128-015-1468-x. Epub 2015 Jan 23.
To investigate the mercury aging process in soils, soil samples were spiked with inorganic mercury (Hg(II)) or methylated mercury (MeHg) and incubated for 2, 7, 14 or 28 days in the laboratory. Potential availability of mercury, assessed by bovine serum albumin (BSA) or calcium chloride (CaCl2) extraction, decreased by 2-19 times for Hg(II) or 2-6 times for MeHg, when the contact time increased from 2 to 28 days. Decreased Hg(II) extraction could be explained by Hg(II) geochemical fractionation, i.e., Hg(II) migrated from more mobile fractions (water soluble and stomach acid soluble fractions) to refractory ones (organo-complexed, strongly complexed and residual fractions) over time, resulting in more stable association of Hg(II) with soils. In addition, decrease of mercury extraction was more evident in soils with lower organic content in most treatments, suggesting that organic matter may potentially play an important role in mercury aging process. In view of the significant decreased Hg(II) or MeHg extraction with prolonged contact time, mercury aging process should be taken into account when assessing risk of mercury in contaminated soils.
为了研究土壤中的汞老化过程，将无机汞（Hg(II)）或甲基汞（MeHg）添加到土壤样品中，并在实验室中培养2、7、14或28天。当接触时间从2天增加到28天时，通过牛血清白蛋白（BSA）或氯化钙（CaCl2）提取评估的汞的潜在有效性，Hg(II)降低了2至19倍，MeHg降低了2至6倍。Hg(II)提取量的减少可以用Hg(II)地球化学分馏来解释，即随着时间的推移，Hg(II)从流动性更强的组分（水溶性和胃酸溶性组分）迁移到难熔组分（有机络合、强络合和残留组分），导致Hg(II)与土壤的结合更加稳定。此外，在大多数处理中，有机含量较低的土壤中汞提取量的减少更为明显，这表明有机质可能在汞老化过程中发挥重要作用。鉴于随着接触时间延长Hg(II)或MeHg提取量显著降低，在评估污染土壤中汞的风险时应考虑汞老化过程。
