Assessment of heavy metal pollution in surficial soils surrounding Zinc Industrial Complex in Zanjan-Iran

摘要

In this study the Zinc Industrial Complex located near the city of Zanjan-Iran was selected for detailed study. The objective of the study was to assess the extent and severity of heavy metal contamination of topsoils in this area. We examined the present degree and spatial distribution of heavy metal concentrations in 15 topsoil samples in the Zinc Industrial Complex in Zanjan. The soils were digested with aqua regia for heavy metal analysis. Pb, Zn and Cd concentrations in the topsoil exhibited anthropogenic increased values. The major sources for the heavy metal contamination in studied area are most possibly emissions from zinc industry. These emissions transported by air and sewage water and industrial sewage effluents have been considered to be responsible for the increased heavy metal concentrations found in the soils of the central studied area. Pb, Zn and Cd concentrations up to 63, 3066, 18.5 mg kg-1 was found in most pollutant area. Concerning the health risk of the population bioavailability and mobility of heavy metals seems to be of major importance, based on the soil properties found in the study area. Heavy metal contamination of soil is widespread and there is a risk of transfer of toxic and available metals to humans, animals, and agricultural crops. If they are phytoavailable, some toxic metals are potentially accumulated in some plants and may pose a threat to humans and grazing animals.