海沟河小流域耕地土壤重金属污染与生态风险评价

为了解海沟河小流域耕地重金属污染现状,采集海沟河小流域耕地表层土壤样品,采用反距离权重插值方法,结合遥感影像解译和ArcGIS地统计方法,分析海沟河小流域耕地重金属Cd、Pb、Hg、Cu、As浓度分布。结果表明:Cd、Pb、Hg、Cu、As平均浓度分别为0.307、23.422、0.041、21.544和12.235 mg∕kg,均高于黑龙江省土壤背景值;Cd浓度超过GB 15618—1995《土壤环境质量标准》二级标准,其余重金属浓度均满足一级标准。重金属空间分布为As浓度自东向西逐渐减小;Cd浓度与As相反,为自东向西逐渐增大。采用潜在生态风险指数法对耕地重金属潜在生态风险进行评价,结果表明,Cd、Hg的潜在生态风险等级分别为高度和中等,Pb、Cu和As为轻度,海沟河小流域耕地潜在生态风险为中等。

Heavy metal pollution and ecological risk assessment of arable land soil in Haigou small watershed

In order to understand the current situation of heavy metal pollution in the arable land of the Haigou small watershed, 106 samples of the surface soil of the arable land were collected in the small watershed, and the inverse distance weighting interpolation method and the Hakanson potential ecological risk index method were used to analyze the distribution of Cd, Pb, Hg, Cu and As in the arable land, in combination with the RS image interpretation and the ArcGIS land statistics method. The results showed that the average contents of heavy metals Cd, Pb, Hg, Cu and As were 0.307, 23.422, 0.041, 21.544 and 12.235 mg∕kg respectively, which were all higher than the background values of Heilongjiang Province. Compared with Soil Environmental Quality Standard (GB 15618-1995), the content of Cd exceeds Class Ⅱ standard, and that of other heavy metals meets Class Ⅰ standard. In terms of the spatial distribution of heavy metals, it was found that the change of As content gradually decreased from east to west, and the change of Cd content was opposite to that of As, which gradually decreased from east to west. The potential ecological risk of the arable land was evaluated by the Hakanson potential ecological risk index method. The results showed that the ecological risk grades of Cd and Hg in the arable land of the Haigou small watershed were relatively high and medium, while that of Pb, Cu and As were mild. Therefore, the potential ecological risk of the farmland in the Haigou small watershed was generally in the middle.