Soil pollution assessment to lead, nickel and cadmium and mapping it by geostatistics in the Tehran south farms

Increasing world population and need to more production, limited water resources and the indiscriminate use of them specially in arid and semi-arid regions and also the huge amount of sullage produced in cities and the necessity for proper disposal of them, increased the urgency (necessity) of using wastes in order to farming & feeding the under- ground aquifers. Cadmium, lead and nickel are such pollutants which can enter to water, soil and plant and finally to human and animals’ food chain from different resources.

This Study was performed to evaluate the amount of soil contamination in the south Tehran farms and mapping the studied area using geostatistical methods. From the 2000 hectares of the agricultural farms around Firooz Abad stream in Tehran south in 2014, 175 soil samples were selected with 300 meters intervals. Two methods of mapping including kriging and Inverse distance weighting (IDW) were used.

Based on mean concentration, the metals in studied area were in following decreasing order: nickel> lead> cadmium. According to the standards proposed by the environmental protection Agency of Iran, 13 and 9 % of soil samples are contaminated to total lead and nickel, respectively.

Due to the importance of point spatial variation of soil pollutants, the IDW method was identified as the suitable method for mapping the concentration of total lead and nickel. The total lead and nickel concentration in about 161 and 14 hectares of the agricultural lands, respectively, were more than allowed limits.