桂林市桃花江水系汞污染现状及评价研究

Pollution Status and Assessment of Mercury in the Watershed of Taohua River, Guilin, China

文章通过对桃花江6个采样点的河水、底泥、近岸土壤、水草、树叶样品的采集．分别采用湿化消解法和巯基棉富集法对植物、土质样品和河水样品进行前处理，结合原子吸收光谱仪测定样品中的总汞含量。结果显示，桃花江从上游到下游各类样品中的汞含量总体趋势是逐渐加重的，河水、底泥、近岸土壤、水草、岸边树叶中汞含量分别为0．1393～0．2570μg／L、0．0975～0．6090μg／g、0．0523～0．3933μg／g、0．1125～0．1820、0．0517～0．1380μg／g，局部采样点的汞含量出现突变增高。根据地表水环境质量标准（GB3838—2002），河水汞含量均达到Ⅳ类水质标准（≤0．5μg／L）。用地积指效法对底泥的汞污染进行初步评价，河流下游污染较为严重，上游基本无污染或轻微污染。由此表明，城市污染大于农村污染，特殊污染源易形成点污染源对河流污染较大，城市工农业生产和居民生活所排放的污染物是河流汞污染的主要来源。

Water, sediment, soil, aquatic plant, leaf samples at six spots from Taohua river which is the most anabranch ot Li River from Xianren bridge to Zhishan bridge. Pretreated separately sediment, soil, aquatic plant, leaf and water by microwave digestion method and enrichment. Contents of total mercury of samples were determined, by analysis. Results showed that general trend of mercury contamination in each sample of Taohua river were aggravated gradually from upstream to downstream. Mercury concentration in water, sediment, soil, aquatic plant, leaf samples separately was 0.1393-0.2570μg/L, 0.0975-0.6090μg/g, 0.0523-0.3933μg/g, 0. 1125-0. 1820μg/g, 0. 0517-0. 1380μg/g. Mercury concentration at part spots appeared augmentation suddenly. According to environmental quality standards for surface water, mercury concentration in river water all reach class IV standard. Applicated Igeo for evaluating mercury conlamination in sediment show that mercury contamination on upstream of Taohua river manifested more severe than on downstream of Taohua river. Because of this, city contamination is more than agriculture contamination, special contamination source was easy formed point source contamination, which influencing water quality, pollutants of industry and agriculture production and live emission are main contamination source of mercury contamination in river.