乌江流域梯级水库入出库河流中总汞和甲基汞的时空分布

2006年1~12月，每月采集乌江流域梯级水库入出库河流水样，用两次金汞齐-冷原子荧光光谱法和蒸馏-乙基化结合GC CVAFS法测定了水中总汞和甲基汞的浓度。结果表明：（1）入出库河流中总汞年均加权浓度分别为317和 2.34 ng/L，甲基汞为014和 0.18 ng/L。（2）不同水库入出库河流中总汞和甲基汞的时空分布特征不同，位于上游第一级的普定和洪家渡水库入库河流中总汞有明显的季节变化趋势，且显著低于出库河流；而甲基汞的季节变化在出库河流中较为明显，而且库龄大的普定、东风、乌江渡水库出库河流中甲基汞浓度显著高于入库河流。（3）相关分析发现水库入库河流中总汞、甲基汞浓度主要受悬浮颗粒物的影响，而与水量间的相关性因水库所处位置的不同而有差异，上游的普定和洪家渡水库中呈显著正相关，其它水库中呈负相关。

TEMPORAL AND SPATIAL DISTRIBUTION OF TOTAL AND METHYL MERCURY IN INFLOWS AND OUTFLOWS OF CASCADE RESERVOIRS IN WUJIANG RIVER

Water samples were monthly collected in inflows and outflows of cascade reservoirs in Wujiang River from January to December in 2006.Total mercury and methyl mercury concentrations were analyzed by cold vapor atomic fluorescence spectrometry and aqueous phase ethylation,GC separation,and CVAFS detection.The results were as follows:(1) Annual volume weighted mean concentrations of total mercury were 317 and 2.34 ng/L,and methyl mercury concentrations were 014 and 0.18 ng/L in inflows and outflows,respectively.There were different mercury distribution characteristics in inflows and outflows of different reservoirs.(2) Total mercury concentrations in inflows were significantly lower than those in outflows,and showed an obvious seasonal variation in Puding and Hongjiadu Reservoir which was the first cascade reservoir in Sancha River and Liuchong River,respectively.However,markedly seasonal variations of methyl mercury were observed in outflows,and their concentrations were obviously higher than those in inflows only in older reservoirs (Puding Reservoir,Dongfeng Reservoir,Wujiangdu Reservoir).(3) Correlation analysis showed total mercury and methyl mercury concentrations in inflows were influenced by suspended matter,and their correlation with water volume varied with the location of reservoir.There was significant positive correlation in the upstream Puding and Hongjiadu reservoirs,and negative correlation in other reservoirs.