贵州乌蒙山区设施土壤重金属污染风险评估与来源解析

Evaluation of Pollution Risk and Source Analysis of Heavy Metals in Greenhouse Soils in Wumeng Mountain Area,Guizhou Province

为评价贵州乌蒙山区设施蔬菜基地土壤重金属污染程度和生态风险,选取研究区种植面积较大的4个设施蔬菜基地为研究对象,共采集144个大棚土样和68个露天土样,测定土壤pH及Cd、Hg、As、Pb、Cr、Cu、Zn和Ni含量,分析研究区设施菜地土壤重金属的污染程度和生态风险,并运用多元统计(简单相关分析和主成分分析)与剖面分异法综合分析研究区设施菜地耕层土壤重金属污染的主要来源。结果表明,研究区设施蔬菜种植会加速土壤酸化,与露天菜地土壤相比,设施菜地耕层土壤pH降低了0.24。研究区设施菜地与露天菜地耕作层土壤重度污染样点占比分别为53.57%与42.86%,中等以上生态风险样点占比分别为82.14%与57.14%,土壤Cd是研究区最主要的污染因子与生态风险因子。研究区设施菜地耕层土壤中As、Pb、Cr、Cu、Ni主要来源于成土母质风化,Cd、Hg、Zn主要来源于成土母质风化与农业投入品。综上所述,研究区设施菜地受重金属污染程度高于露天菜地,尤其应控制外源Cd、Hg、Zn的投入,并加强农产品重金属监测,为贵州乌蒙山区设施农产品安全生产提供了理论支撑。

To evaluate the degree of heavy metal pollution and ecological risks in the soil of vegetable greenhouses in Wumeng mountain area of Guizhou province,4 vegetable bases in Wumeng mountain area of Guizhou province was taken as the research object. 144 soil samples form greenhouse field and 68 soil samples from nearby open field were used to determined the pH and contents of Cd,Hg,As,Pb,Cr,Cu,Zn and Ni. The degree of soil heavy metal pollution and ecological risk in the study area were evaluated. Multivariate statistics and profile differentiation were used to comprehensively analyze the main sources of heavy metal pollution in the topsoil of greenhouse in the study area. The results showed that vegetables cultivation in greenhouse fields accelerated soil acidification. Soil pH in greenhouse decreased 0.24 compared with open field soil. In the study area,the percentage of heavily contaminated soil sample points in topsoil of the greenhouse and open field were 53.57% and 42.86%,respectively,and the percentage of sample points with medium or higher ecological risk were 82.14% and 57.14%,respectively. The Cd was the most important ecological risk factor in the study area. In topsoil of the greenhouse,the As,Pb,Cr,Cu and Ni were mainly derived from the weathering of parent materials,while the Cd,Hg and Zn were mainly derived from the weathering of parent materials and agricultural inputs. In conclusion,the degree of heavy metal contamination in the greenhouse was higher than that in the open field,so the input of exogenous Cd,Hg and Zn should be controlled and the monitoring of heavy metal in agricultural products should be strengthened in greenhouse fields of study area,which provided theoretical support for the safe production of agricultural products in the Wumeng mountains of Guizhou.