利用黏土矿物计算背景值评估沉积物重金属污染

Evaluating pollution of heavy metals with backgrounds calculated by clay minerals

综合考虑样品性质及粒度的影响,提出利用黏土矿物计算背景值的方法。实例研究表明,研究区沉积剖面不同深度样品的背景值存在一定的差异。将实测值与背景值之比视为富集因子,发现As、Cr、Cu在剖面的中下部弱富集;Pb在剖面中部弱富集;Zn与Cd在剖面的不同位置的富集程度变化较大,在中部显著富集,表层及底部中度富集。与传统方法相比,该方法综合考虑了粒度和样品性质的影响,并且可以计算出不同位置样品的背景值,使得评估结果更加准确。

A method to calculate background values by using the clay minerals is proposed,which is taking the effects of sample features and particle sizes into consideration. The results show that there is certain difference among background values of heavy metals from samples in different depths. The ratio of measured and calculated value is defined as the enrichment factor,and As,Cr and Cu are found to be enriched weakly in the middle-lower of the section. Pb is enriched in the middle of the section. While the enrichment factors of Zn and Cd change greatly in different depths with significant enrichment in the middle section and moderately enrichment in the surface and bottom. Compared with traditional method,the influence of granularity and sample characteristics are considered in this method. And the background values of heavy metals in different depths can be calculated,which makes the evaluated results more precise.