曹妃甸围填海土壤重金属积累的磁化率指示研究

Heavy Metals Accumulation in the Caofeidian Reclamation Soils: Indicated by Soil Magnetic Susceptibility

环境磁学方法在土壤重金属污染识别中被广泛运用,其具有简单、快速、无破坏性和灵敏度高的特点.本研究以北方典型的围填海区——曹妃甸工业区土壤为例,开展土壤磁化率对重金属积累的指示研究.根据研究区的土地功能规划特征,将研究区土壤分为工业区土壤、生活区土壤以及自然滩涂和湿地土壤共3类.共采集35个表土（0-10 cm）样品和3个土壤剖面柱状样,分析土壤中的磁化率（χlf）、铁（Fe2O3）含量及重金属（Cr、Ni、Cu、Zn、As、Pb、Mn、V）元素含量.结果表明：工业区表土磁化率和重金属含量空间分异性较高,受工业生产的影响明显;工业区和生活区剖面中0-20cm的表层土壤中,各重金属均出现不同程度的富集现象,而远离工业区的潮滩剖面中重金属含量变化不明显.研究区表土磁化率与重金属含量总体上有相关性：其中工业区表土磁化率与Fe2O3、Ni、Cu、As和V呈现极显著（P〈0.01）正相关,可以作为指示土壤重金属积累的指标.但在生活区和自然潮滩湿地土壤中,土壤磁化率的高低不能很好地指示重金属的积累情况,推测可能与土壤中磁性物质来源以及潮滩湿地的环境条件有关.

The environmental magnetism method has been widely applied to identify soil heavy metal pollution,which is characterized by simplicity,efficiency,non-destructivity and sensitivity. The present study used magnetic susceptibility to assess the accumulation of heavy metals in soils of the Caofeidian industrial zone which is a typical reclamation area in northern China. The study area was divided into three sub-zones based on the function,including industrial zone,living zone,natural tidal flat and wetland. A total of 35 topsoil samples（ 0-10 cm） and 3 soil profiles were collected from the three sub-zones. Magnetic susceptibility（ χlf）,iron oxide（ Fe2O3）contents and heavy metals contents（ Cr,Ni,Cu,Zn,As,Pb,Mn and V） of the samples were analyzed. The results showed that χlf values and heavy metals contents exhibited higher spatial variability in the top soil of the industrial zone,indicating the severe impacts of industrial activities. In the soil profiles of the industrial and living zones,all heavy metals were enriched to different degrees in the upper layer（ 0-20 cm）. However,there was no significant change of heavy metal contents in the soil profiles of tidal flat which was far from the industrial area. The χlfvalue was significantly（ P〈0. 01） positively correlated with the contents of Fe2O3,Ni,Cu,As and V in the industrial top soil. This indicated that χlfcould be used as an indicator for heavy metal accumulation in the industrial zone.However,the χlfvalue was not suitable to be an indicator to show the heavy metal accumulation in the soils of living zone and natural tidal flat. This might be associated with the different sources of magnetic materials among the different sub-zones and the special characteristics of the soils in the tidal flat and wetland.