青海典型工业区耕地土壤重金属评价及源解析

Evaluation and source analysis of heavy metal in cultivated soil around typical industrial district of Qinghai province

为了解黄河流域工业园区附近耕地土壤重金属污染现状、分布特点及污染来源,在青海省湟水流域甘河工业园区采集了138个表层土壤样点,测定了Cd、As、Pb、Cr、Cu、Ni、Zn等7种重金属的含量及土壤pH值,以《土壤环境质量农用地土壤污染风险管控标准》为评价标准,采用地累积指数、污染负荷指数、主成分分析、正定矩阵因子分析等方法对研究区耕地土壤重金属污染进行了研究分析.结果表明:7种土壤重金属的浓度范围分别为Cd(0.16~21.80mg/kg)、As(3.68~20.80mg/kg)、Pb(17.00~223.40mg/kg)、Cr(47.22~389.24mg/kg)、Cu(16.03~46.06mg/kg)、Ni(21.33~93.24mg/kg)、Zn(48.60~1535.10mg/kg),其中Cd污染最严重,存在13个高风险值点,52个中风险值点;其次为Zn,存在13个中风险值点;Cr和Pb分别存在2个和1个中风险值点,其他重金属的采样点均为低风险.研究区耕地土壤重金属污染以中部偏东地区最为严重,与研究区工厂企业的位置一致,两种主要重金属污染元素Cd和Zn的污染均表现出以工厂企业为中心,中心区污染最严重,向外污染程度逐渐降低.综合地累积指数和污染负荷指数分析的结果,研究区绝大多数地区污染较轻,在中部偏东工业园区周边地区污染较为严重,Cd和Zn是其主要贡献元素.造成研究区耕地土壤重金属污染的来源主要包括交通运输、工业生产、农业活动、燃煤发电及自然成土过程等.

In order to understand the current status,spatial distribution characteristics,and pollution sources of heavy metal pollution in the cultivated soil around the industrial district of the Yellow River Watershed,138 surface soil samples were collected from Ganhe Industrial District in Huangshui Watershed,Qinghai Province.The factors including the soil pH and seven heavy metal elements(Cd,As,Pb,Cr,Cu,Ni,and Zn)were measured in the laboratory.According to the standard named Soil environmental quality:Risk control standard for soil contamination of agricultural land,methods including the geo-accumulation index,pollution load index,principal component analysis and positive matrix factorization were adopted to evaluate the pollution level and analyse the sources of the heavy metals in the study area.A series of results have been obtained.The concentration ranges of the seven soil heavy metal elements were Cd(0.16~21.80 mg/kg),As(3.68~20.80 mg/kg),Pb(17.00~223.40 mg/kg),Cr(47.22~389.24 mg/kg),Cu(16.03~46.06 mg/kg),Ni(21.33~93.24 mg/kg),Zn(48.60~1535.10 mg/kg),respectively.The Cd pollution was the most serious,which had 13 high-risk samples and 52 medium-risk samples.Zn was the second polluting element,which had 13 medium-risk points.There were only two medium-risk samples and one medium-risk sample for Cr and Pb,respectively.For the other elements,all the samples were at low risk.The pollution of heavy metals in the cultivated soils was mostly distributed in the central-eastern part of the study area,which was roughly consistent with the location of the factories and enterprises in the study area.The pollution areas of the two major elements,Cd and Zn,were distributed around the factories and enterprises and showed an obvious trend of gradually decreasing from the centre to outside.The results of the geo-accumulation index and pollution load index showed that most regions of the study area were less polluted.The pollution was more serious in the area around the central-eastern industrial park,and Cd and Zn were the main contributing elements.The sources of heavy metal pollution in the cultivated soil of the study area mainly included transportation,industrial emission,agricultural activities,coal-fired power generation,and natural soil formation processes.