磁湖表层沉积物重金属污染特征及生态风险评价

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Surface Sediments from the Cihu Lake in Huangshi City

于2011年9月对磁湖南北湖两个断面采集了29个表层沉积物样品,并用火焰-原子吸收分光光度法测定其重金属含量(Cu、Ni、Fe、Zn、Pb、Cd、Cr)。结果表明,南湖和北湖的平均浓度分别为155.41、67.60、4050.00、415.05、195.09、3.58、113.04mg/kg和100.30、40.87、4088.05、351.80、159.43、1.38、214.43mg/kg;地累积指数评价结果显示南湖表层沉积物重金属污染要高于北湖;南北湖重金属Zn、Cr在岸边和湖中区域含量均比较高,Cu、Pb、Cr污染程度在空间分布上呈现靠近岸边区域高于湖中区域的特点,Ni的含量分布相对均匀;潜在生态风险系数指出南湖和北湖重金属Cr均存在很强的生态风险,南湖综合潜在生态风险高于北湖;主成分和相关性综合分析表明磁湖表层沉积物重金属污染主要来源于工业源,同时也受燃烧源影响。

Twenty-nine surface sediments from the southern and northern profiles of the Cihu Lake were sampled during Septem- ber 2011. The concentrations of heavy metals （Cu, Ni, Fe, Zn, Pb, Cd, Cr） in the sediments were measured by atomic ab- sorption spetrophotometry （AAS）. The results showed that the concentrations of the metal elements in the southern and north- ern profiles are 155. 41, 67. 60, 4050.00, 415.05, 195.09, 3.58 and 113.04 mg/kg, 100.30, 40.87, 4088.05, 351.80, 159.43, 1.38 and 214.43 mg/kg, respectively. The assessment of geoaccumulation index indicated the south lake pollution lev- el of heavy metals is higher than the north lake pollution level of heavy metals. The contaminations of Zn and Cd in the south- ern and northern profiles close to the shore and center are all high. Spatial distribution features of Cu, Pb and Cr in the lake show that the contents of those metals are higher in the shore than in the center, and the distribution of concentrations of Ni is relatively uniform. The potential ecological risk indexes indicated that Cu in the southern profile is higher than in the northern profile, and the comprehensive ecological risk of the southern profile is higher than that of the northern profile. The results of principal components analysis （PCA） and correlation showed that the contamination of heavy metals in surface sediments of the Cihu Lake is mainly caused by industrial activities, but also influenced by ignition sources.