呼和浩特市不同功能区土壤重金属污染特征及评价

选择呼和浩特市居民区、科教区、城市公园、商业区、道路、工业区和开发区为研究对象,共采集62个样品.通过分析不同功能区土壤重金属含量,采用单因子污染指数法和内梅罗综合污染指数法评价重金属污染程度,主成分分析重金属污染的成因和来源,旨在为防治城市土壤重金属污染提供理论依据.呼和浩特市不同功能区土壤7种重金属的含量表明,其中5种重金属的平均含量均超过内蒙古自治区土壤背景值,重金属Cu和Zn含量分别达到背景值的2.33倍和1.85倍;单因子污染指数评价表明,不同功能区土壤存在不同程度重金属的污染,重金属Cu在商业区呈重度污染.不同重金属元素平均污染程度为:Cu>Zn>Cr>Mn>As>Ni>Pb;内梅罗综合污染指数评价表明,商业区污染最严重,呈重污染程度;其次是道路,污染水平为中度污染;科教区和城市公园污染程度最轻.不同功能区土壤重金属的综合污染指数大小为:商业区(3.03)>城市道路(2.12)>居民区(1.98)>科教区(1.81)>工业区(1.72)>开发区(1.36)>城市公园(1.28);主成分分析表明,呼和浩特市土壤不同重金属来源存在差异,其中Cr、Cu、Mn、Pb和Zn主要来自交通污染源和生活废弃物的堆放,Ni和As目前仍然主要受自然因素控制,来源于自然源.呼和浩特市土壤重金属的污染已经对城市生态系统的健康发展构成了一定程度的威胁.

Characteristic and Evaluation of Soil Pollution by Heavy Metal in Different Functional Zones of Hohhot

The residential areas, cultural and educational areas, city parks, commercial areas, urban roads, industrial zones, and development zones in Hohhot were selected as the research objects. Sixty-two soil samples were collected by triple subsampling technique in the seven functional zones. The aim of this study is to control the soil heavy metal pollution of Hohhot and provide the basic information. To investigate and analyze the heavy metal pollution in soil in different functional zones of Hohhot, the pollution of heavy metal was assessed with single factor pollution index and Nemerow integrated pollution index, and the pollution sources were discriminated by Principal Component Analysis. Contents of seven kinds of heavy metals were analyzed in different functional zones of Hohhot. The mean contents of heavy metals in soil samples exceeded the corresponding background values in the Inner Mongolia Autonomous Region. The mean contents of Cu and Zn were 2.33 and 1.85 times, respectively, as high as the soil background values of the Inner Mongolia Autonomous Region. Single factor pollution index showed that the urban soil in Hohhot has been polluted by heavy metals. The Cu pollution was the most severe in commercial areas, and the pollution degree was in the following order: Cu>Zn>Cr>Mn>As>Ni>Pb. Nemerow integrated pollution index showed that soils from the commercial areas were seriously contaminated by heavy metals. The soil of urban roads was moderately polluted. The soils from cultural and educational areas and the city parks were slightly polluted. The Nemerow integrated pollution index of the seven areas ranked as follows: commercial areas (3.03)>urban roads (2.12)>residential areas (1.98)>cultural and educational areas (1.81)>industrial zones (1.72)>development zones (1.36)>city parks (1.28). The results of Principal Component Analysis showed that the heavy metals in soil of Hohhot came from different sources. Cr, Cu, Mn, Pb and Zn were mainly originated from anthropogenic sources while Ni and As were mainly controlled by natural sources. The healthy development of urban ecosystem has been threatened by soil heavy metal pollution in Hohhot.