Mapping the heavy metals proportions in surface soils of the closed Kurdistan cement factory zone

Cement manufacturing is the most important and influential industry in the economic prosperity of the country. However, this can be an entrance source for heavy metals to environment. The main objectives of the present study were to identify the spatial variability and main sources of heavy metals including Cr, Mn, Ni, Co, Cu, Cd, As and Zn in surface soils of the closed Kurdistan cement factory zone by conducting multivariate geostatistical analysis assisted with ArcGIS 10.2 tool. Multivariate geostatistics was used to survey the spatial distribution of studied heavy metals and their reasons in the studied area.
In the present study, 88 samples of surface soils were collected in radiuses of 500, 1000, 2000 and 3000 m from the center of the cement factory from two depths of 0–15 and 15-30 cm.
According to the gained results, three principal factors were appeared with more than 90% of the total variance through multivariate statistical analysis for heavy metals. For mapping the distribution of the heavy metals amounts, four different models including circular, spherical, exponential and Gaussian with methods of simple Kriging, ordinary Kriging, universal and simple Co-Kriging were identified as the optimum models using ArcGIS 10.2.. The accoracy of the methods were evaluated using coefficient determination, mean absolute error, mean bias error and root mean square error.
Heavy metals mapping confirmed that the levels of Cd, As, Pb and Cu in surface soils closed to the factory are higher than global average amount. Also, it can be mentioned that geological structure of the area plays most important role in soil pollution. However, anthropogenic activities, particularly cement plant are considered as another effective factor on soil pollution in the studied area.