山美水库沉积物重金属污染状况及风险评价

Pollution and Potential Ecological Risks of Heavy Metals in Sediment of Shanmei Reservoir

为了解泉州市山美水库沉积物重金属空间分布及污染水平,采用电离子耦合法（ICP-MS）测定了库区20个采样点不同分层的67个沉积物样品的w（As）、w（Zn）、w（Cd）、w（Pb）、w（Cu）、w（Cr）,并采用地累积指数法和潜在生态危害指数法进行了库区重金属污染程度及生态风险的评价.结果表明,Cd是山美水库最主要的重金属污染物,不同分区分层w（Cd）平均值为0.24～0.49 mg/kg,受人为活动影响较大.不同分区w（Cd）存在差异,污染层的Ⅰ区、Ⅱ区显著高于Ⅲ区（P〈0.05）.Pb和Cu虽有累积但污染情况较轻.重金属污染来源主要为入库河流承接的沿程生活、工业及农业污染物,部分来源为周边村庄的生活及农业污染物.地累积指数法评价结果显示,山美水库各重金属元素的平均污染程度由强到弱依次为Cd（轻度污染）〉Cu（清洁）〉Pb（清洁）〉As（清洁）〉Zn（清洁）〉Cr（清洁）.潜在生态风险结果显示,6种元素中,Cd的生态风险为＂强＂,其他重金属则是低或无生态风险.研究显示,在开展底泥疏浚工作中,疏浚深度的确定应综合考虑沉积物氮、磷及重金属污染状况,并需在底泥堆场采取防渗措施避免重金属对土壤及地下水产生二次污染.

A total of 67 samples from different layers（ e. g.,polluted layer,transition layer and normal layer） were taken from 20 regions in Shanmei Reservoir. The total contents of six heavy metals（ As,Cd,Cr,Cu,Pb and Zn） were measured by ICP-MS,and the distribution and sources of the heavy metals in the reservoir were analyzed using comparative analysis and correlation analysis. The geoaccumulation index was used to evaluate the pollution levels of the heavy metals in Shanmei reservoir,and the potential ecological risks of the heavy metals in the sediment were further assessed. The results showed that： Cd,Cu and Pb accumulated in the sediment for decades. Cd was at the highest pollution level of the six heavy metals,and was strongly affected by artificial activity. The average contents of Cd in the different zones and layers ranged from 0. 24 to 0. 49 mg/kg. In the polluted layer,Cd contents in zones Ⅰ and Ⅱ were significantly higher than zone Ⅲ（ P 〈 0. 05）. The contents of Pb and Cu in the sediment were higher than the background value in Fujian,but the Pb and Cu contamination levels were much slighter compared to Cd. The heavy metals were mainly from the domestic,industrial and agricultural pollutants from the upstream zone,and some might be from the domestic and agricultural pollutants in surrounding villages. According to the geoaccumulation index,the rank of pollution level of the six heavy metals in Shanmei reservoir were： Cd（ lightly polluted） 〉 Cu（ clean） 〉 Pb（ clean） 〉 As（ clean） 〉 Zn（ clean） 〉 Cr（ clean）. Potential ecological risk results showed that Cd had a high ecological risk,while the other five heavy metals had a low ecological risk. Therefore,whentaking dredged sediment decontamination technologies,the depth of dredged sediment should be determined by the pollution level of TN,TP and heavy metals,and anti-leakage and other measures should be taken to prevent heavy metal pollution.