甘肃嘉峪关市表层土壤重金属空间分布与评价

Spatial Distribution and Assessment of Heavy Metals in Surface Soil,Jiayuguan City, Gansu Province

为研究嘉峪关市重金属分布对环境的影响,分析了嘉峪关市表层土壤重金属分布和含量变化,并评价其富集程度,判断其来源和影响因素.采用电感耦合等离子体质谱仪(ICP-MS)测量嘉峪关市134个表层土壤样品中六种重金属元素(Cr、Cd、Cu、Pb、Ni、Zn)的含量,其平均含量分别为281.6 mg/kg、0.35 mg/kg、60.68 mg/kg、51.39 mg/kg、108.65 mg/kg、161.0 mg/kg.在土壤重金属含量空间分布的基础上,用内梅罗指数法和地累积指数法对研究区土壤重金属富集程度进行了评价,六种元素地累积指数排序依次为:Cr>Cd>Pb>Cu>Zn>Ni,各功能区重金属元素整体富集程度依次为工业区>戈壁>生活区>农业区.戈壁采样点重金属元素含量(除Ni外)高于农业区,除工业因素外,地表植被的缺失加剧了戈壁地区重金属元素的富集.结合主成分分析,重金属元素空间展布,及内梅罗指数评价和地累积指数评价,分析了各元素可能的来源,认为Cr、Zn主要来自以钢铁生产加工为主的工业源,Cd、Cu、Pb来自于交通源,Ni可能与钢铁生产或当地背景值有关.通过分析嘉峪关市土壤重金属分布情况,以期为改善当地土壤质量提供科学依据,为我国西北地区土壤重金属的研究提供参考.

Jiayuguan,located in the northern Qilian Mountains,is a new steel industry and tourism city in NW China at the transportation junction of the ancient Silk Road.To measure the concentration of heavy metals in the surface soil of Jiayuguan city and evaluate their concentration and determine the sources of heavy metal pollution,the amounts of six heavy metal elements(Cr,Cd,Cu,Pb,Ni,Zn)in 134 surface soil samples were determined by inductively coupled plasma mass spectrometer(ICP?MS).The average concentrations were:Cr 281.6 mg/kg;Cd 0.35 mg/kg;Cu 60.68 mg/kg;Pb 51.39 mg/kg;Zn 108.65 mg/kg;and Ni 161.0 mg/kg.Their concentration in the soil was evaluated by the Nemero comprehensive index(PN)and the geoaccumulation index(Igeo).The pollution levels of the geoaccumulation index were in the order of Cr>Cd>Pb>Cu>Zn>Ni.The overall heavy metal pollution levels in each functional area was industrial area>gobi area>living area>agricultural area.The concentration of heavy metal elements(except Ni)in the gobi area were higher than those in agricultural areas.In addition to industrial factors,the absence of surface vegetation aggravated the enrichment of heavy metal elements.The possible sources of pollution of each element were analyzed by principal component analysis,combined with the spatial distribution of concentration,Nemero index and the geoaccumulation index.Cr and Zn are mainly industrial products of steel production and processing.Traffic is the source of Cd,Cu and Pb.The sources of Ni are possibly related to the steel industry of background value.