衡水湖底泥中7种重金属元素含量的分布及其潜在生态风险评价

于2018年6月25~27日,在河北省衡水湖设置了22个采样点,采集0~50 cm深度的底泥样品,测定底泥样品中的7种重金属元素含量;并采用地累积指数法和潜在生态危害指数法,对7种重金属元素潜在生态风险进行评价。研究结果表明,衡水湖底泥中的7种重金属元素Cd、Hg、As、Pb、Cr、Cu和Zn的质量比分别为0.046~0.290 mg/kg、0.010~0.064 mg/kg、4.31~10.70 mg/kg、11.7~29.5 mg/kg、48.5~87.5 mg/kg、10.7~24.7 mg/kg和35.2~198.0 mg/kg;在22个采样点中,有9个采样点底泥中的Cd元素含量的地累积指数大于0,即这9个采样点存在轻微的Cd污染,处于轻微危害等级;每种重金属元素含量分别与其它大多数金属元素含量显著相关,表明这些重金属元素可能具有同源性,各重金属元素含量都分别与底泥中的有机质、全氮含量显著相关,Hg、Pb和Zn元素含量与全磷含量显著相关;衡水湖底泥中的7种重金属元素综合潜在生态风险指数为90.23,表明衡水湖底泥中的重金属元素存在轻微的潜在生态风险。

Distribution of Contents of 7 Kinds of Heavy Metal Elements in the Sediments of Hengshui Lake and Their Ecological Risk Assessment

Sediment is an important indicator of heavy metal pollution in water environment, which has an important impact on the quality of water environment. Heavy metals are a typical kind of cumulative pollutants. Once pollution occurs, it is difficult to remove and recover them, and easily adsorbed and accumulated in sediments of water environment. The geo-accumulation index method can directly analyze the pollution degree of heavy metals, while the potential ecological risk index method is more comprehensive and simple, and can quickly and accurately evaluate the potential ecological hazards of heavy metals. The combination of the two methods can form a relatively complete evaluation system. The 22 sampling sites were set in Hengshui Lake in Hebei province, and sediment samples at 0-50 cm depth were collected on 25-27 June,2018. Contents of 7 kinds of heavy metal elements in the sediment were determined, and the potential ecological risks were evaluated based on the methods of geo-accumulation index and potential ecological risk index. The results showed that the contents of the seven heavy metal elements(Cd, Hg, As, Pb, Cr, Cu, Zn) in the sediment at 0-50 cm depth of Hengshui Lake were 0.046-0.290 mg/kg, 0.010-0.064 mg/kg, 4.31-10.70 mg/kg, 11.7-29.5 mg/kg, 48.5-87.5 mg/kg, 10.7-24.7 mg/kg and 35.2-198.0 mg/kg, respectively. In the 22 sampling sites, geoaccumulation indexes of contents of Cd in 9 sampling sites were greater than 0, and the pollution of Cd in sediment was slight. There were significant correlation between the contents of each kind of heavy metal element and the majority of other heavy metal elements, which indicated that those heavy metal elements might have homology. The correlation with organic matters and total nitrogen was also significant, and the contents of Hg, Pb and Zn were also significant with total phosphorus content. The comprehensive potential ecological risk index was 90.23, indicating that there was a slight potential ecological risk in the sediment of Hengshui Lake. The pollution of heavy metal elements in the sediment of Hengshui Lake was slight, and its pollution source might be mainly domestic sewage discharged from urban areas and surrounding villages,with only slight potential ecological risk.