基于地统计学土壤重金属背景值研究及评价

The Soil Background Values of Heavy Metals and Ecological Risk Assessment Based on the Geo-statistical Analysis

该文以广东省东部某县级区域作为研究区,选取远离人类活动影响的“自然土壤”采集土壤样品,利用地统计方法对“自然土壤”6种重金属元素进行分析,剔除异常值,确定研究区域内土壤重金属背景值,基于该背景值对区域内农业土壤包括水田和其他农用地重金属累积进行研究,并开展生态风险评价。研究表明:(1)受成土母质影响,研究区Cd、Pb、Cu重金属元素背景值高于广东省背景值,Cr元素背景值低于广东省背景值,As、Hg背景值与广东省背景值接近。(2)不同耕作方式下,不同重金属土壤累积程度有些许差异,Pb、Cu、Cr元素水田与其他农用地的累积程度相似,Hg元素在水田土壤中富集程度稍高于其他农业用地,Cd、As元素在其他农业用地的富集程度高于水田用地。(3)所有样本点Pb、As、Cu、Hg重金属元素均为轻微风险,仅有少数样本点Cd和Cr存在中等风险及以上级别,不同土地利用类型之间稍有差异。重新确定研究区背景值可为该流域土壤环境研究提供参考,同时也为其他区域土壤背景值的确定提供方法参考。

A county-level region in eastern Guangdong Province was selected as the study area.Soil samples were collected from the“natural soil”which was far away from the impact of human activities.Six kinds of heavy metal elements in the“natural soil”were analyzed by geo-statistics,and the abnormal values were eliminated to determine the background value of heavy metals in the study area.Based on the background value,the accumulation of heavy metals in agricultural soil including paddy field and other agricultural land was studied,and also the ecological risk assessment.The results show that the back⁃ground values of Cd,Pb,Cu in the study area are higher than those in Guangdong Province,while the background value of Cr is lower than that of Guangdong Province,the background values of As and Hg are close to those of Guangdong Province.The accumulation degree of Pb,Cu and Cr in paddy field was similar to that in other agricultural land,Hg was slightly higher than that in other agricultural land,and Cd,As in other agricultural land was higher than that in paddy field.Pb,As,Cu and Hg were in mild risk of all.But for Cd and Cr,only a few sampling sites were in medium risk or above level,and there were differences among different land use types.The determination of the background value of the study area can provide a reference for the study of soil environment in this region and also provide a method reference for the determination of soil background value in other regions.