Distribution of heavy metals in urban soils – a case study of Danang-Hoian Area (Vietnam)

Abstract

 This work is part of a research study which is intended to study the degree of anthropogenic influences of the trace metal distribution of soils from Danang-Hoian area (Vietnam). Cu, Ni, Zn and Zr show significant effects in most of the cultivated soil categories, especially in the industrial soils. Extremely high levels of Pb (up to 742 μg/g) are observed in the industrial soil category, which shows an enrichment factor 114 as compared to rural soils. Cd shows only a relative local enrichment with the maximum level of 4.6 μg/g in urban soils. Sequential extraction was performed in selected samples to evaluate the geochemical trace metals. The result indicates that Zn and Cr are mainly found in the crystal and amorphous Fe oxide bounded forms. The contents of Cr in these fractions comprise more than 94% of total extractable Cr. In the case of Zn, 85% of total extractable Zn is in fractions F_V and F_VI. Cu is mainly found in the organic fraction at an average of 39.3% of total extractable content. On the other hand, heavy metal contents show an increasing tendency in the fine fraction (silt and clay).