平顶山市火葬场周边农田土壤重金属空间分布、富集与来源分析

Spatial distribution,enrichment and source identification of heavy metals in agricultural soils around the crematory in Pingdingshan City,China

火葬场在火化遗体时会向周边环境排放多种重金属,引起周边土壤重金属积累和污染.以河南省平顶山市火葬场为中心,布设西北(NW)、西南(SW)、东南(SE)和东北(NE)4条3 km长的采样断面.采集表层土壤(0~20 cm)样品157份,测定其Hg、Cd、As、Pb、Cu、Zn、Cr和Ni含量,结合富集系数(EF)和正定矩阵因子分析(PMF)探讨火葬场周边农田土壤重金属富集特征及来源.结果表明:①除土壤As的平均含量低于河南省土壤背景值外,其余重金属均高于河南省和平顶山市土壤背景值,但总体上没有达到污染水平.在主导风向下风向的NW断面上,多数重金属平均含量高于其他断面.②土壤中8种重金属的平均EF均处于中等及以上富集水平,其中Cd处于强富集水平,Hg处于中富集至强富集水平,且具有NW>SW>NE>SE的趋势,表明土壤重金属存在不同程度的人为来源.③扣除非火葬场因素对土壤重金属空间分布的影响,Hg、Cd含量沿断面多呈单峰分布,Pb、Cu、Zn和As多呈双峰分布,Ni和Cr多呈递减分布,表明8种重金属不同程度地与火葬场烟尘排放有关.④火葬场周边农田土壤中的Hg是火葬源重金属,Cd、Zn、Cu和Pb是农业⁃火葬⁃交通混合源重金属,As、Ni和Cr是自然⁃火葬混合源重金属.

Heavy metals will be discharged and cause the accumulation in the surrounding environment of crematory along with the cremation of the body.In this study,four 3⁃kilometer⁃long sampling sections were set up in the Northeast(NE),Southeast(SE),Northwest(NW)and Southwest(SW)directions of the Pingdingshan crematory in Henan province,respectively.A total of 157 topsoil samples were collected to determine the concentrations of Hg,Cd,As,Pb,Cu,Zn,Cr and Ni.Combined with the Enrichment Factor(EF)and the Positive Matrix Factorization(PMF)model,the accumulation characteristics and sources of heavy metals in agricultural soils around the crematory were discussed.The results show that:①Only the average concentration of As was lower than the soil background value in Henan Province for all the heavy metals.Although the average concentrations of other heavy metals were higher than the background value of soil,they did not reach the pollution level in general.The average concentration of most heavy metals in the NW section with downwind direction of the prevailing wind generally was higher than that in other sections.②The average enrichment factors of the eight heavy metals were at or above the moderate enrichment level,in which Cd was at strong enrichment level,Hg was at the moderate to strong enrichment level,and showed the trend of NW>SW>NE>SE,indicating that the soil heavy metals came from anthropogenic sources to varying extent.③Removing the influence of non⁃crematory the spatial distribution patterns of Hg and Cd in the soil are mostly unimodal,while Pb,Cu,Zn and As were mostly bimodal,and Ni and Cr were mostly decreasing,indicating that the eight heavy metals were related to the smoke emission from crematory to certain extent.④The main source of Hg in the agricultural soil was from crematory,while Cd,Zn,Cu and Pb were from mixed sources of agriculture⁃crematory⁃transportation,and As,Ni and Cr were from mixed sources of nature⁃crematory.