典型矿业城市的土壤重金属分布特征与复合污染评价——以“镍都”金昌市为例

通过对甘肃省金昌市(镍矿城市)建成区的土壤重金属调查研究,揭示了其重金属来源、污染现状及其环境风险。结果表明:当地主要矿产品Ni和Cu两种重金属的土壤污染最严重,与《土壤环境质量标准》(GB15618-1995)的III级标准比较,样品Ni和Cu的超标率分别为70%和57%,污染面积分别为26 km2和24 km2;土壤As和Cd污染主要集中在矿冶区和尾砂库附近,居民区土壤污染程度低;土壤Cr污染出现在尾砂库和采矿区附近,污染面积为3 km2。在城区土壤中,Co、Cu、Cd、Pb与Zn的污染来源及空间分布具有相似特征,而土壤As污染与Ni污染特征相近。Nemero综合指数评价结果表明,高风险区域主要分布在东部矿冶区、北部尾砂库和西南角采矿区,城市居民区的土壤重金属污染水平较低。

Mining urban soil pollution: concentrations and patterns of heavy metals in the soils of Jinchang, China

As is known,urban soil has an important effect on the urban sustainable development ant its conteminations have been paid more and more attention.To investigate the impact of mining activities on soil contamination and environmental risk,the present study was undertaken as a preliminary survey on an urban scale in Jinchang,Northwest China.Because of mining and smelting,the soils were severely contaminated by Ni and Cu,70% and 57% of which in samples exceeded the limit values(GB15618-1995 III).The soil contaminated areas with Ni and Cu were estimated to be 26 and 24 km~(2),respectively.Cd and As concentrations in urban soils exhibited the anthropogenic induced increasing values around industrial districts and tailing pools.Fortunately,the values were in most cases below tolerable values of soil in the residential areas.The Cr contaminated soils were mostly distributed in places near tailing pools and mining areas. According to the results of statistical analysis,heavy metals were classified into three groups: 1) Co,Cu,Cd,Pb and Zn;2) As and Ni;and 3) Cr.The major sources for the heavy metal contamination in Jinchang city are released from the smelting industrial district to the east of the city,tailing pools to the north of the city and mining district to the south west of the city,to which the highest concentrations of heavy metals are generally located.Based on heavy metals in the soils investigated,the results of Nemero index assessment suggested that the health risk in the residential areas seems to be of minor importance.However,direct ingestion of soil and inhalation of dust coming from seriously contaminated areas may contribute largely to the accumulation of heavy metals in human bodies.