青藏高原纳木错流域水体总汞的时空分布特征

为研究青藏高原纳木错流域水体中总汞的时空分布特征,于2007～2010年对纳木错湖表层水及入湖河水进行了采样,检测了其总汞浓度,并分析了总汞浓度与降水量、河水径流量等的关系.结果表明,纳木错表层湖水和河水中的总汞质量浓度均值分别为(1.09±0.73)ng.L-1和(2.87±2.59)ng.L-1,显著低于受到汞污染的水体.近岸带湖水的总汞浓度在季风期远大于非季风期,而其浓度水平和空间变化明显大于湖心区.河水的总汞浓度季节变化明显,表现为季风盛期最高且波动最大,而季风期后最低,这与降水量变化趋势基本一致.对你亚曲的定点观测表明,河水总汞浓度的时间变化与径流量一致.入湖河流总汞浓度的空间分布特征在不同的时间表现不同,这可能是由河流的流域面积、流域内土壤汞本底值及补给方式的差异引起的.

Spatial and Temporal Distribution of Total Mercury (T-Hg) in Different Water Bodies of Nam Co, Tibetan Plateau

To investigate the tempo-spatial distribution of total mercury (T-Hg) concentration in water bodies in the Nam Co basin on the Tibetan Plateau, inflowing river water and surface lake water samples were collected from 2007 to 2010. The T-Hg concentration and its relationship with precipitation and river runoff were analyzed. The results showed that the average T-Hg concentration was (1.09±0.73) ng·L^-1 and (2.87±2.59) ng·L^-1 for surface lake water and river water, respectively, both of which were significantly lower than those of Hg contaminated waters. T-Hg concentration in off-shore lake water was much higher during the monsoon season than in the non-monsoon season, and its level and spatial variation were significantly greater than those in central lake water. T-Hg concentration in river water showed significant seasonal variations with the highest values during the monsoon season and the lowest during the post-monsoon season, which were in accordance with the variations of precipitation. A fixed point observation at Niyaqu River indicated that the temporal changes of the T-Hg concentrations in river water were in accordance with those of the runoff. The spatial distribution features of T-Hg concentrations in inflowing river water varied in different periods, possibly resulting from the differences in drainage areas, background mercury levels in soils, and water supplies for rivers at different locations of the Nam Co basin.