中国西北地区典型钢铁工业城市表土重金属污染的环境磁学响应

Magnetic Responses of Heavy Metals in Urban Topsoil of Typical Steel Industrial City,Northwest China

以嘉峪关市为研究靶区,系统采集城区表土样品58件,对其进行环境磁学和重金属元素(Cd、Cr、Cu、Mn、Pb、V、Zn、Fe)质量分数分析。结果表明:嘉峪关市表土以低矫顽力磁铁矿为主导,磁晶粒度以较粗的假单畴(PSD)和多畴(MD)颗粒为主;城区表土亚铁磁性矿物浓度和磁性颗粒大小远高于国内综合型大城市表土;市区反映磁性矿物含量的参数呈现出以酒钢厂和废渣场为中心的高值区域,并随着污染源距离的增加向周围递减;嘉峪关市表土重金属Cd、Cr、Cu、Mn、Pb、V、Zn、Fe质量分数与反映磁性矿物含量的参数具有显著共变性,二者的高值分布与反映磁晶粒度参数的高值分布成盈缺呼应关系。然而嘉峪关市土壤母质磁性颗粒本底值较粗,与污染土壤特征相似,因此对西北地区而言,亚铁磁性矿物浓度相对磁晶粒度可以更好地指示钢铁厂周边土壤重金属的污染程度。

Magnetic methods provide a fast tool for delineation of industrial pollution.58 soil samples were collected for magnetic properties and heavy metal（Cd,Cr,Cu,Mn,Pb,V,Zn,Fe） mass fraction analysis in Jiayuguan City,Northwest of China.The results revealed that the magnetic properties of soil samples are predominated by low-coercivity magnetite,pseudo single domain（PSD）-multi domain（MD） in size,and characterized by high content of ferrimagnetic fraction and coarse particle size.Additional,as the distance increasing to steal manufactory,concentration of ferrimagnetic fraction is decreasing and the particle size is smaller.The high positive consistency is shown between heavy metal materials（Cd,Cr,Cu,Mn,Pb,V,Zn,Fe） and ferrimagnetic fraction,and low negative with magnetic particle size due to presenting nearly same particle size in magnetic fraction between pollution material and soil.So,the magnetic parameters which are related to content of magnetic fraction,just as χlf,ARM,and SIRM,which can be used as an indicator of heavy metal pollution.