Cadmium and mercury in topsoils of Babagorogor watershed, western Iran: Distribution, relationship with soil characteristics and multivariate analysis of contamination sources

Publication date: May 2014
Source:Geoderma, Volumes 219–220
Author(s): Mohammad Tahsin Karimi Nezhad , Khosro Mohammadi , Ali Gholami , Abbas Hani , Mohammad Sediq Shariati
The main objectives of this study were to identify spatial variability and main sources of cadmium and mercury in rural soils of Babagorgor watershed. A total of 87 composite soil samples were collected in an area of about 1352km². The average concentrations of the analyzed elements in topsoil were 3.289mgCd/kg and 0.632mgHg/kg. To identify the sources of heavy metals, we used: (a) the relationship between the heavy metal content in soils and the origin of the parent material; (b) the comparison of heavy metal in soils among different land uses; and (c) the heavy metal distribution in the study area. The results indicated that land use had no significant effect on Cd and Hg concentrations, and that the concentrations of Cd and Hg were primarily controlled by the parent materials of soils. High Cd concentrations in soils can be explained by occurrence of the magmatic rocks in the area. Mercury concentrations were associated with areas characterized geomorphologically as alluvial deposits at the lowest altitudes within the region. In fact, high adsorption of Hg with silt fraction allowed for its migration towards the drainage network.