乌江流域表层水体中汞的形态与时空分布特征

Seasonal and Spatial Distribution Characteristics of Speciation of Mercury in the Wujiang River System

为了弄清乌江流域表层水体中汞的形态与时空分布规律,于2009年1~12月,每月采集乌江流域河流表层水样,采用两次金汞齐-冷原子荧光光谱法和蒸馏-乙基化结合GC-CVAFS法测定了水中不同形态汞的浓度。结果表明：（1）监测期间各采样点总汞、甲基汞、溶解态汞、颗粒态汞、活性汞、颗粒态甲基汞、溶解态甲基汞的年均算数平均值分别为5.20±10.89、0.09±0.20、3.31±10.66、1.89±1.08、0.30±0.36、0.06±0.19、0.04±0.03 ng/L。不同形态汞的沿程分布显示,水库的修建改变了原有的汞的地球化学过程。（2）通过不同季节各形态汞浓度的变化发现,河流表层水中不同形态汞有明显的季节变化趋势。（3）相关分析发现,总汞受总悬浮颗粒物含量的影响相对较大;活性汞浓度的季节变化可能与降雨对乌江水体的影响有关。

Water samples were monthly collected from the surface of the Wujiang River during January to December in 2009.Speciation of mercury and its concentrations were analyzed by cold vapor atomic fluorescence spectrometry（CVAFS） and aqueous phase ethylating,GC separation,and CVAFS detection techniques.The results are presented as follows ：（1） The average concentrations of mercury in total,particulate,dissolved,reactive,total methyl and dissolved methyl species in the Wujiang River were 5.20±10.89,0.09±0.20,3.31±10.66,1.89±1.08,0.30±0.36,0.06±0.19,0.04±0.03 ng/L,respectively.The distribution of Hg along the Wujiang River system showed that the construction of cascade reservoirs has an impact on the initial biogeochemical cycling of Hg.（2） The seasonal variations of speciation of mercury in surface water of the Wujiang River were obviously observed.（3） By means of correlation analysis total mercury was influenced by suspended matter,and the seasonal variations of reactive mercury might be influenced by the acidity of rainfall.