Arsenic heavy metal mapping in agricultural soils of Alborz province, Iran

Soil is continuously polluted via the entrance of pollutants and so crops cultivated in these land are exposed to heavy metals pollution. In this research, the concentration of arsenic was evaluated in agricultural soils of Alborz province, Iran. Achieving this goal, 254 soil samples were taken from the soil surface (0-30 cm) and soil texture and chemical characteristics were measured. The spatial distribution of arsenic was evaluated using Gaussian model and the map of arsenic pollution was prepared using Kriging method in ArcGIS. After determination of effective parameters on total arsenic using PCA analysis, a linear regression relationship between arsenic and other important parameters was introduced. Based on the prepared map, about 80% and 15% of the total cultivated area of Alborz land had arsenic lesser than 10 and 10-20 ppm, respectively. Only 5% of cultivated land located in the south-west of Alborz province had arsenic about 20-21.63 ppm. Because this area is located in vicinity of industrial town of Alborz province and industrial and urban waste waters entered in agricultural land. About 99% of studied soil samples had I-geo<0 which classify as practically uncontaminated. On the other hand, 96% and 4% of soil samples had CF<1 and 1-3, which indicate low and moderate contamination, respectively. The amount of potential ecological risk of arsenic was between 0 and 16.64 demonstrating all studied soil samples had a low one. Accordingly, the maximum rate of total arsenic reported in agricultural soils of Alborz province was 21.63 mg kg(-1) which is lower than the allowed limit for agricultural land of Iran.