盘龙江口滇池沉积物重金属的分布及污染评价

Distribution and Pollution Evaluation of Heavy Metals in Sediments of Lake Dianchi in the Estuary of the Panlongjiang River

对盘龙江口滇池沉积物重金属的分布进行了研究并对其污染状况进行了评价。结果表明:Cd、Cr、Cu和Zn在表层沉积物中的含量较高(Pb在中层的含量较高),且随采样深度的增加含量递减,这几种元素的含量顺序基本为Zn>Cu>Cr=Pb>Cd。表层沉积物中各元素之间的相关性较差,中层和底层的相关性较好。表层沉积物重金属与颗粒的相关性较差。除底层沉积物中的重金属与有机质达到显著或极显著相关外,表层和中层的相关性都较差。所研究重金属(除Pb外)随与河口距离的增加,含量降低。利用地积累指数对该河口重金属的污染进行评价,发现重金属污染都在中等程度以上,其污染程度顺序为:Cd>Zn>Cu=Pb>Cr,表明盘龙江入滇池口区的沉积物已受到严重污染。

Distribution of heavy metals （Cd, Cr, Cu, Pb and Zn） in sediments of Lake Dianchi in the estuary of the Panlongjiang River was studied. Pollution degree of heavy metals was also evaluated based on the geological accumulation index （I-geo）. The results showed that the concentration of heavy metals （except Pb） decreased with the increasing sampling depth. In terms of concentration, the heavy metals followed a decreasing order of Zn〉Cu〉Cr≈Pb〉Cd in the sediments. Relativities were found insignificant between heavy metals in the surface sediments （0 - 5 cm）, and were, however, significant in the layers 5 - 10 cm and 10 - 20 cm in depth. Relationship between most of the heavy metals and organic matter weren＇t significant in the layers, 0 - 5 cm and 5 - 10 cm in depth, but significant in the layer 10 - 20 cm in depth. Relationship between the heavy metals and sediments particles size （clay fraction, silt fraction and sand fracton） weren＇t significant in the layer 0 - 5 cm in depth. Concentrations of the heavy metals （except Pb） decreased with the increasing distance from the estuary of the Panlongjiang River. The heavy metals were evaluated based on I-geo index, indicating moderate to strong contamination of Cu, Pb and Zn, extremely strong contamination of Cd, and little contamination to moderate contamination of Cr, which means pollution degrees of the heavy metals followed the sequence of Cd 〉 Zn 〉Cu=Pb 〉 Cr.