黄石市城市边缘区土壤重金属分布特征、风险评价及溯源分析

Heavy metals in peri-urban soil of Huangshi:Their distribution,risk assessment and source identification

为掌握黄石市城市边缘区农用土壤环境质量现状,在高密度表、深层土壤采样的基础上,重点分析了土壤重金属元素的分布规律和特征,对其进行了生态环境风险评价,并对重金属元素成因进行了溯源分析。结果表明:研究区土壤中的重金属元素As、Pb、Hg、Cd、Zn、Ni、Cu和Cr含量范围分别为(5.2~155.9)×10^(-6)、(19.2~426.1)×10^(-6)、(0.012~1.823)×10^(-6)、(0.03~4.59)×10^(-6)、(34.8~529.6)×10^(-6)、(8.5~86.2)×10^(-6)、(16.52~104.39)×10^(-6)和(51.2~145.5)×10^(-6),平均含量均超过区域土壤环境背景值,且Cd超过农用地土壤风险筛选值。重金属污染物主要集中在表层40 cm以上土壤中,土地类型中以水田和旱地污染为主,污染物中以Cd、As和Pb为主要特征。水田中As、Pb、Cu和Zn为轻度污染,Cd和Hg为中度污染,而Cr和Ni无污染;旱地和林地中As、Pb和Hg为轻度污染,Cd为中度污染,而Cr、Cu、Ni和Zn无污染。多元统计分析表明,研究区土壤中Cr和Ni为自然源成因,与成土母质相关;Cd和Pb、As和Hg主要为人为源污染,与黄石市高强度工矿业生产和硫化物矿物酸化释放有关;而Cu和Zn为混合源成因,部分来源于土壤环境背景,部分来源于人类活动和工业生产排放。

To study the quality of the arable soil in peri-urban area of Huangshi City,the present research focused on analyzing heavy metals distribution characteristics,assessed its risk to environment,and subsequently identified its sources by multivariate statistical analysis based on high-density topsoil and subsoil sampling.The results show that the content of heavy metals in the soil isas follows:As(5.2×10^(-6)~155.9×10^(-6)),Pb(19.2×10^(-6)~426.1×10^(-6)),Hg(0.012×10^(-6)~1.823×10^(-6)),Cd(0.03×10^(-6)~4.59×10^(-6)),Zn(34.8×10^(-6)~529.6×10^(-6)),Ni(8.5×10^(-6)~86.2×10^(-6)),Cu(16.52×10^(-6)~104.39×10^(-6))and Cr(51.2×10^(-6)~145.5×10^(-6)).The average content of Cd exceeds the regional soil environmental background value,and Cd even exceeds the soil risk screening value of agricultural land.Heavy metal pollutants are mainly concentrated in the topsoil above 40 cm.Among the land use types,paddy lands and dry lands are heavily polluted,and Cd,As and Pb are the main pollutants.In paddy lands,As,Pb,Cu and Zn exhibit slight pollution,Cd and Hg exhibit moderate pollution,whereas Cr and Ni do not exhibit pollution.In dry lands and forest lands,As,Pb and Hg exhibit slight pollution,Cd exhibits moderate pollution and Cr,Cu,Ni and Zn do not exhibit pollution.The multivariate statistical analysis indicates that Cr and Ni in the soil of the study area are of natural origin and related to the parent material of the soil.Cd,Pb,As and Hg are mainly of anthropogenic pollutants,which is related to high-intensity industrial and mining production and sulfide mineral acidification release in Huangshi City.However Cu and Zn constitute mixed sources,partly from soil environmental background,and partly from human activities and industrial production emissions.