【摘要】 对北京城东附近某苗圃内典型的土壤污染剖面进行了环境磁学和地球化学分析,发现某些重金属(Pb、Zn、Sr、Ba、Cu)和磁性参数呈现相同的垂向变化趋势,都在37cm以上显示高值区,磁化率均值达到192.02×10-8m3/kg,如Pb含量达到67.62mg/kg,而在37cm以下,明显属低值区,磁化率均值只有18.38×10-8m3/kg,Pb含量也只有23.43mg/kg.借助于指标聚类分析和主成分分析方法,揭示出各种指标之间的内在联系,表明磁参数与Pb、Zn、Sr、Ba、Cu等元素显著相关,彼此的相关系数都达到0.90以上,属于同一类别的隶属度在80%以上,说明磁指标可以作为这些重金属污染的一种代用指标.利用模糊C均值聚类分析分辨出了土壤上部污染物堆积层和下部未污染土壤背景2种不同的特征段.更多还原

【Abstract】 Two short cores were obtained from a tree nursery in eastern Beijing city, and gray-black pollutants can be found within the uppermost 37cm of the soil profile. All of them were measured, and one of them, profile BJ722 of 90cm length, is discussed in detail in this paper. Magnetic measurements, element contents and grain size analysis were carried out to understand the vertical characteristics of magnetic minerals and heavy metals in soil from anthropogenic pollutants, as well as the relationship between magnetic parameters and heavy metals. Magnetic proxies show similar pattern comparing to heavy metal elements, with higher concentration above 37cm. Index cluster and principal component analysis indicate that strong correlation between magnetic parameters and Pb, Zn, Sr, Ba and Cu (R2>0.90, membership>80%). Fuzzy C-means cluster analysis (FCM) shows that anthropogenic pollutants accumulated and enriched above 37cm. Below 37cm, soil is unpolluted. Our work demonstrates that magnetic measurements can be used to delineate anthropogenic pollution in the soil profile and to identify the migration depth and the depth of unpolluted soil with the help of multivariate statistics.更多还原