灌洋水库底泥重金属污染现状及生态风险评价

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

【目的】研究福建永定灌洋水库底泥中重金属的空间分布及污染水平。【方法】采用电感耦合等离子体质谱法(ICPMS)测定了库区38个采样点沉积物中的6种重金属(As,Zn,Cd,Pb,Cu和Cr)含量,并采用单因子污染指数法、内梅罗综合污染指数法和潜在生态危害指数法进行底泥重金属污染程度及生态风险的评价。【结果】水库底泥重金属从水库边到水库中心呈现含量逐渐上升趋势(南岸水产养殖区除外),上游含量总体低于中游和下游。底泥中Cr,As,Pb无超标点位,Cd超标十分严重,Cu和Zn超标较严重;单因子污染指数法评价结果显示:灌洋水库底泥各重金属元素的平均污染程度由强到弱依次为Cd(重污染),Cu(重污染),Zn(中污染),Cr(非污染),Pb(非污染),As(非污染)。内梅罗综合污染指数法评价结果显示水库底泥重金属污染达到重污染水平,污染程度明显。潜在生态风险结果显示:6种元素中,Cd的潜在生态风险为"极强",Cu的潜在生态风险为"强",As、Pb、Cr和Zn的潜在生态风险为"轻微"。多因子综合潜在生态危害指数平均值为330.13。【结论】底泥重金属污染潜在生态危害程度为"强",表明底泥整体处于严重污染状态。

[Purposes]To understand the spatial distribution and pollution levels of sediment heavy metals in the reservoir of Guanyang. [Methods] 38 samples were collected to measure the total contents of six heavy metals including arsenic （As）, cadmium （Cd）, Chromium （Cr）, copper （Cu）, lead （Pb） and zinc （Zn） using Inductively Coupled Plasma Mass Spectrometry （ICP-MS）. Then the single factor pollution index and Nemerow pollution index were used to evaluate the pollution levels of the heavy metals in Guanyang Reservoir and the potential ecological risks of the heavy metals in the sediment were further assessed. [Findings] Results showed that heavy metal content increased gradually from the shore to the center of the Guanyang reservoir, where the upstream heavy metal content was lower than that of middle and lower reaches. Cr, As, Pb content in the sediment were lower than standard values （Illevel standard of GB15618-1995）, while Cd exceeded standard value seriously. Cu and Zn were serious but slighter than Cd. According to the single factor pollution index, the rank of pollution level of the six heavy metals in Guanyang reservoir were： Cd （heavy level pollution） 〉 Cu （heavy level pollution） 〉Zn （medial level pollution）〉Cr （uneontamination） 〉 Pb（uncontamination） 〉As （uncontamination）. According to the Nemerow pollution index, the reservoir sediment was heavy polluted by heavy metals. Potential ecological risk results showed that Cd had a very high ecological risk; Cu had a high ecological risk, while the other heavy metals had a low ecological risk. The average of RI was 330. 13. [Conclusions] Potential ecological risk degree of sediment heavy metal pollution in the reservoir was the ＂strong＂, and the sediment was in a state of serious pollution.