Determination of heavy metal risk and their enrichment factor in intensive cultivated soils of Tokat Province

Abstract

Heavy metal contamination has caused serious environmental and health-related problems around the world. This research was conducted in arable lands of some basins located on Tokat province. The aim of this present study was to determine I-) some physico-chemical properties of soils, ii-) to find heavy metal (HM) content and their enrichment factor (EF) and iii-) to detect relationship between some physico-chemical properties and HM concentration. To identify the concentrations and sources of heavy metals, 280 soil samples (0-20 cm) were collected from the study area. Subsequently, in order to evaluate natural or anthropogenic sources of heavy metal content and their EF in agricultural fields, the concentrations of some HMs (Cd, Co, Cu, Cr, Ni, Pb and Zn) and some physico-chemical properties of soil samples were analyzed. The results showed that mostly the concentration of Ni followed by Cr exceeded their threshold levels. The local pollutions from Ni and Cr were attributed to the natural influences (particularly due to parent material). The concentrations of the other HMs are relatively lower than the critical values. The mean values of the HMs contents arranged in the following decreasing order: Ni>Cr>Cu>Zn>Co>Pb>Cd in the studied soil sample. In addition, it was found significantly positive relation between Pb and OM while the same relation was also found clay content and Cd and Pb. On the other hand, according to EF of HMs in total soil samples, Cd, Ni and Cr have found 16%, 10% and 6% soil samples as moderate enrichment class, whereas 55% and 1% of the total soil samples were determined significant enrichment class in terms of Cd and Ni elements. Besides, all other HM elements did not exceed minimal enrichment level. However, in some regions of the study area, the Cu, Cd and Pb contents were also slightly raised, this case possibly stems from anthropogenic effects such as excessive P fertilization, field traffic and pesticide using.