鲁西莱阳茌梨产地小流域沉积物重金属生态风险评价及来源分析

Ecological Risk Assessment and Source Analysis of Heavy Metals in Sediments of Small Watershed in Laiyang Pears Producing Area

富集在河流沉积物中的重金属是长期影响河流地表水和周边农田土壤环境生态的潜在威胁。采集鲁西五龙河小流域表层沉积物样品,分析As、Cd、Cr、Cu、Hg、Ni、Pb和Zn共8种重金属的含量,采用地累积指数法、潜在生态危害指数法评价重金属元素污染现状和潜在生态风险,运用正定矩阵因子矩阵法对沉积物重金属来源进行解析。结果表明,沉积物重金属中Cr、Cu、Hg和Ni的平均含量明显高于相关背景值,显示一定的富集特征。重金属污染程度排序为Ni>Hg>Cu>Cr>Cd>Zn>As>Pb,其中Cu、Hg和Ni为偏中度污染,Cd和Cr为偏轻度污染,As、Zn和Pb为无污染。沉积物重金属潜在生态风险低、中、较高等级风险占比分别为40.8%、48.1%和11.1%,Hg和Cd为主要潜在生态风险元素,分别表现为较高潜在生态风险和中等潜在生态风险,风险点主要分布在五龙河汇合口和富水河中。研究区重金属污染来源主要有自然源(Cr和Ni)、混合源(As、Cd、Hg和Pb)和果园农药(Cu和Zn),三者贡献率分别为30%、31%和39%。

.Heavy metals enriched in river sediments are a potential threat to river surface water and surrounding farmland soil environment in a long time.Through collecting surface sediment samples from Wulonghe small watershed in Chili area in Laiyang,the contents of 8 kinds of heavy metals have been analyzed,including As,Cd,Cr,Cu,Hg,Ni,Pb and Zn,present condition of heavy metal pollution and potential ecological risks have been evaluated by using geological accumulation index method and potential ecological hazard index method,and the sources of heavy metals in sediment have been explained by using positive matrix factor matrix method.It is showed that the average contents of Cr,Cu,Hg and Ni in the heavy metals in the sediments are significantly higher than relevant background values with a certain enrichment characteristics.The order of heavy metal pollution degree is Ni>Hg>Cu>Cr>Cd>Zn>As>Pb,in which Cu,Hg and Ni are moderately polluted,Cd and Cr are slightly polluted,and As,Zn and Pb are non polluted.The potential ecological risks of heavy metals in sediment are low,medium and high,accounting for 40.8%,48.1%and 11.1%respectively.Hg and Cd are main potential ecological risk elements,and showing higher potential ecological risks and medium potential ecological risks respectively.The risk points are mainly distributed in the confluence of Wulong river and Fushui river.The heavy metal pollution sources in the study area mainly include natural sources(Cr and Ni),mixed sources(As,Cd,Hg and Pb)and orchard pesticides(Cu and Zn),with their contribution rates of 30%,31%and 39%respectively.