内蒙古畜禽养殖场周边土壤重金属污染特征及评价

Characteristic and Evaluation of Soil Pollution by Heavy Metal Adjacent to the Livestock and Poultry Feedlots in Inner Mongolia Autonomous Region

于2015年5—8月采集内蒙古自治区东部、中部和西部地区32个畜禽养殖场周边共160个土壤样品,分析8种重金属含量。通过单项污染指数法和内梅罗综合污染指数法评价畜禽养殖场周边土壤重金属的污染程度,主成分分析重金属污染的成因和来源。结果表明,除Hg和As外,Cd、Pb、Cr、Cu、Zn和Ni 6种重金属的平均值均高于内蒙古自治区土壤背景值,其中Cd是背景值的2.14倍。单项污染指数评价表明,重金属Cd在东部畜禽养殖场周边土壤中呈中度污染,在中部和西部地区畜禽养殖场周边土壤中呈轻度污染。不同重金属元素平均污染程度为:Cd>Pb>Cr(Ni)>Zn>Cu>As>Hg。内梅罗综合污染指数评价表明,东部地区畜禽养殖场周边土壤污染最严重,为中度污染,中部和西部地区畜禽养殖场周边土壤均为轻度污染。不同地区畜禽养殖场周边土壤重金属内梅罗综合污染指数大小顺序为:东部地区(2.27)>西部地区(1.52)>中部地区(1.35)。主成分分析结果显示,内蒙古不同地区畜禽养殖场周边土壤不同重金属的来源存在差异,其中Pb、Cr、Cu、Zn和Ni主要来源于畜禽粪便和冲洗禽舍等污水的不当排放;Hg主要来源于自然源。

160 soil samples were collected from the sampling sites adjacent to 32 livestock and poultry feedlots which locate in eastern,central and western part of Inner Mongolia Autonomous Region,and contents of eight heavy metals were analyzed.Single factor pollution index and Nemerow integrated pollution index were used to evaluate the pollution degree and Principal Component Analysis was used to analyze the causes and sources of heavy metal pollution.The results showed that except for Hg and As,the mean contents of six heavy metals,which were Cd,Pb,Cr,Cu,Zn and Ni,exceeded the corresponding background values in the Inner Mongolia Autonomous Region.The mean contents of Cd was 2.14 times of the soil background value of the Inner Mongolia Autonomous Region.Single factor pollution index showed that the soil surrounding livestock and poultry farms in the west was contaminated by Cd moderately,while in the east lightly.The average pollution degree was in the following order:Cd>Pb>Cr(Ni)>Zn>Cu>As>Hg.Nemerow integrated pollution index showed that the soils adjacent to eastern livestock and poultry feedlots were moderately polluted by heavy metals.The soils adjacent to western and central livestock and poultry feedlots were mildly polluted.The Nemerow integrated pollution index of the different areas ranked as follows:Eastern region(2.27)>Western region(1.52)>Central region(1.35).The results of Principal Component Analysis showed that the heavy metals in soil adjacent to the livestock and poultry feedlots of different regions of Inner Mongolia came from different sources.Pb、Cr、Cu、Zn and Ni were mainly originated from livestock manure and waste water which were discharged irregularly,while Hg was mainly from natural sources.