辽河干流消落区沉积物重金属污染特征研究

通过测定辽河干流消落区10个断面中0~5cm、5~15cm、15~30cm深沉积物中重金属Pb、Cu、Zn、Cd含量,揭示消落区干－湿交替下沉积物重金属的污染特征.采用原子吸收分光光度计测定重金属含量,并采用地质累积指数与潜在生态危害指数评估重金属污染状况.结果表明,除Cd外,Cu、Zn与Pb的含量均值分别为31.4mg/kg、28.14mg/kg、43.75mg/kg,均低于中国土壤环境质量标准I级土壤标准;Cd含量均值1.438mg/kg,是中国土壤环境质量标准I级土壤标准的7.19倍,是辽河水系沉积物平均值的1.29倍,辽宁省土壤背景值的13.31倍,表明研究区Cd污染严重.地质累积指数评价表明,Pb、Cu、Zn的污染程度低于1级,Cd达2级中度污染以上,在通江口达3.92,为5级强污染;据潜在生态危害评价,达牛渡口上游干流潜在生态危害指数为强以上,通江口生态危害指数最高,且生态危害主要来源于Cd.相关性分析表明,Pb、Cu与Zn间相关性极显著,可能有相同的污染源,Cd有单独的污染源.

Characteristics of heavy metals pollution in sediments of the hydro-fluctuation belt in the Liao River of Liaoning Province,Northeast China

In order to investigate the characteristics of sediment heavy metals pollution in the hydro-fluctuation belt along the Liao River in Liaoning Province, the amounts of Pb, Cu, Zn and Cd in the sediments were detected, and the pollution status in different layers of the sediment (0~5cm, 5~15cm and 15~30cm in depth) were examined and evaluated with geo-accumulation index and Hǎkanson potential ecological risk index, respectively. In the surface sediments of the hydro-fluctuation belt, the amount of Cd (1.438mg/kg) was 7.19, 1.29 and 13.31fold of the Class I limit of the China National Standards of Soil Environmental Quality, the average Cd concentration in Liao river, and the background value in soil of Liaoning Province, indicating that the sediments in the hydro-fluctuation belt was polluted. The amounts of Pb, Cu, Zn were 31.4, 28.14, and 43.75mg/kg, respectively. Geo-accumulation index of the hydro-fluctuation belt showed that the pollution degree of the examined heavy metals except Cd were lower than the first grade within a range of unpolluted to moderately polluted. However, the pollution degree of Cd exceeded Class two, higher than the moderate pollution. The highest Geo-accumulation index of Cd was 3.92 appeared in Tongjiangkou, indicating that a heavy pollution occurred in that spot. Hǎkanson potential ecological risk index analysis indicated that the potential ecological risk of the heavy metals in the upstream of the ferry of Daniu was very serious, potential risk in Tongjiangkou was even more serious. The risk was largely dependent on Cd pollution. Correlation analysis revealed that pollutants Zn, Pb and Cu most likely came from the same sources and that Cd came from a different source.