Spatial distribution of heavy metal content in soils around an industrial area in Southern Turkey

The purpose of this study is to investigate heavy metal contents and to determine their spatial distribution in soils around industrial areas. A total of 102 soil samples were collected by a variable-distance grid sampling technique at depths 0–5 and 5–20 cm from 51 locations. Samples were analyzed for pH, electrical conductivity (EC), organic matter (OM), particle size distribution (sand, silt, and clay), and available heavy metal (Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn) concentrations. Descriptive statistics, correlation, and principal component analysis (PCA) were applied to the transformed data. Maps of the spatial distribution of heavy metal concentrations in the research area were generated using kriging interpolation of data for surface and subsurface soils. Mean pH, EC, and OM varied between 7.93–7.98, 293.7–275.7 μS cm−1 and 5.83–3.61 %, respectively. Average values of the heavy metals at both depth ranges showed the following order: Zn > Fe > Mn > Ni = Pb > Cu > Co > Cr > Cd. PCA analysis showed that Cd, Cu, Pb, and Zn may have a similar source. Contents of these metals were the highest around the industrial area and roads. Fe was high in the industrial and forest areas, whereas Mn and Ni contents were high in agricultural and forest lands. The spatial distribution of Co appears controlled by both natural and anthropogenic factors, and that of Cr by only natural factors.