滇池西白沙小流域沉积物重金属污染及来源研究

Pollution and Sources Study of Heavy Metals in Sediments of Xi Baisha Small Watershed in Dianchi

以滇池西白沙小流域为研究对象,研究沉积物中重金属Cu、Zn、Pb、Cd和Cr的污染状况和来源,结果表明:0~31 cm沉积柱对应沉积年代为1881-2011年,平均沉积速率约为0.20 cm/a.总体来说20世纪60年代之前各重金属在沉积物中的含量较低且较稳定,之后呈现上升趋势.随时间推移,越接近沉积物表层重金属环境风险越大.潜在生态危害指数法评价显示,Cu、Zn、Pb、Cd和Cr单一元素危害程度分别为:中等危害、中等危害、轻微危害、极强危害和轻微危害,危害指数RI整体表现为上升趋势,生态风险主要来自Cd元素.从不同重金属非稳定态含量来看,各重金属对环境产生生态危害风险大小顺序为Cd>Zn>Cu>Cr>Pb.小流域沉积物中Pb与Cu、Zn与Cr在0.05水平达到显著相关,相关系数分别为0.45和0.38.提取重金属污染来源的三个主成分,结合西白沙小流域所处的云南地区工矿业发展情况分析,该区域重金属污染主要来源为:钢铁化工废水排放贡献率为27.06%,矿业开采加工和交通运输降尘的贡献率为25.03%,矿业开采加工废水的贡献率为21.94%,其他来源占25.97%.

Taking Xi Baisha small watershed in Dianchi as the study object,heavy metals of Cu,Pb,Cd,Zn and Cr pollution status and source in sediments were studied,and the results showed that: 0-31 cm samples time was 1881-2011 in the deposition,the average sedimentation rate was about 0. 20 cm/a. The contents of heavy metals in sediments were generally lower and more stable before 1960,and then showed up was ward trends. As time went on,the closer to the surface of the sediments was,the greater the environmental risk of heavy metals was. The potential ecological hazard index method showed that the damage degree of single elements in Cu,Zn,Pb,Cd and Cr were moderate,moderate,minor,extreme and minorand,and the hazard index RI showed an upward trend as a whole. The ecological risk of pollution mainly came from Cd elements. From the unstable content of different heavy metals,the heavy metals had great ecological harm to the environment. The order of risk was Cd>Zn>Cu>Cr>Pb. Pb and Cu,Zn and Cr in the sediments of the small watershed were significantly correlated at 0.05 level,and the correlation coefficients were 0.45 and 0.38. The extraction of three principal components of heavy metal pollution sources,analysised with industrial development in Yunnan area,the main sources of heavy metal pollution were: chemical wastewater emission of iron and steel accounted for 27.06%; mining processing and transportation of dust contribution rate was 25. 03%,the contribution rate of mining processing wastewater was 21.94%,other sources accounted for 25.97%.