Heavy metals are one of the most important soil contaminants due to their toxicity and non-degradability in the environment. Because of industrial development in Iran, investigation of heavy metal pollution in soils around industrial region is essential. The aim of this study was to evaluate the spatial distribution of lead (Pb), cadmium (Cd) and nickel (Ni) in the soil around Isfahan Oil Refinery and Power Plant of ShahidMontazeri (Bakhtyardasht region of Isfahan). The predominant wind direction of the study area was mapped using software WRPLOT. 15 soil samples from the West- East transect and 10 soil samples from North-South transect from 0 to 30 cm depth were collected. Total and bioavailable amount of heavy metals were determined using Aqua regiaand AB-DTPA, respectively. Some soil characteristics such as electrical conductivity, cation exchange capacity, organic carbon, lime and soil pH were also measured. To interpret the data, correlation analysis, principal component analysis and cluster analysis, as well as geological maps, land use, the distance from the sampling sites and the smoke-stacks of industries and road were used. Comparison of heavy metal concentrations with maximum permitted values of Iranian Environmental Protection Agency showed that Pb and Cd concentrations were in the range of standard values, whereas Ni concentration was higher than the permitted value, and the heavy metal contents in soils of two transects were significantly different. Factor and cluster analyses revealed that natural and anthropogenic factors might control the concentrations of Ni and Pb-Cd in the area, respectively. The most important factor affecting bioavailability of the metals was lime content of the soil. Spatial distribution of Pb and Cd in the area showed the highest total and bioavailable contents of the metals were in the North-South transect between the mountains of Isfahan University of Technology. Therefore, topography and distance to industrial area could affect the soil metal content. Overall, the results of this study revealed that the soils of North-South direction of the industrial region of Bakhtiardasht were more polluted with Pb and Cd than the soils of the other direction (West-East). Keywords : Heavy metals, Principal component analysis, Cluster analysis, Soil pollution, Industrial activities
