贵阳市阿哈湖水体和沉积物间隙水中汞的含量和形态分布初步研究

为了弄清楚酸性矿井废水的排放是否对阿哈湖造成了汞污染,研究了阿哈湖中汞的各种赋存形态(包括溶解气态汞、活性汞、颗粒态汞、溶解态汞、溶解态甲基汞、颗粒态甲基汞以及沉积物间隙水体的溶解态汞、溶解态甲基汞)及其在水体和沉积物间隙水中的剖面分布.结果显示,阿哈湖水体中溶解气态汞的浓度为0.04～0.09ng·L-1,活性汞浓度为0.2～1.1ng·L-1,总汞浓度为2.08～19.14 ng·L-1,甲基汞浓度为0.002～0.43 ng·L-1;在沉积物间隙水体中溶解态汞浓度为1.72～19.12 ng·L-1,溶解态甲基汞浓度为0.03～1.57 ng·L-1.实验数据表明,溶解态甲基汞浓度在沉积物下2～5 cm处最高,随着深度增加而逐渐降低,其与硫酸盐还原菌(SRB)分布呈现较好的吻合,说明水体-沉积物界面是甲基汞的产生地点;并且在沉积物中高浓度硫酸根浓度高达1100 mg·L-1的条件下,硫酸根浓度与甲基汞浓度依然一致.

The concentration and distribution of different mercury species in the water columns and sediment porewater of Aha Lake

In order to find out whether Aha Lake was polluted by the acid wasted mining water or not, the concentration and distribution of different mercury species in the water columns and sediment porewater collected from the Aha Lake were investigated. The concentrations of HgT ranged from 2.08 to 19.14 ng ·L^-1, DGM ranged from 0.04 to 0.09 ng·L^-1, HgR ranged from 0.2 to 1.1ng·L^-1 and MeHgT ranged from 0.002 to 0.43ng·L^-1 in the Aha Lake water columns. In the sediment porewater, however, the concentrations of HgD varied from 1.72 to 19.12 ng·L^-1, and MeHgD ranged from 0.03 to 1.57 ng·L^-1. The results indicated that highly elevated MeHgD concentrations in the porewater were obtained at the depths from 2 to 5 cm in the sediment profile, and decreased sharply with depth. A positive correlation has been found between MeHgD formation and sulfate-reducing bacterial activity. These highly elevated concentrations of MeHgD obtained in the intersurface between waters and sediments suggesting a favorable methylation conditions. Moreover,even under the conditions of high SO₄^2- concentrations, reaching up to 1100mg·L^-1, a strong correlation beteen MeHgD and SO₄^2- was observed as well.