Investigation of heavy element pollution in surface soils (Study area: Shahrekord city)

The study area is located in Chaharmahal and Bakhtiari province and includes Shahrekord and its villages. The highest outcrop of the region is related to the Mesozoic limestone formations in which the Upper and Lower Cretaceous limestones have the largest extent, and Precambrian sediments have a limited extent. The existence of different age facies along with mining, industrial, and agricultural activities can provide the necessary grounds for soil contamination with heavy elements. In the present research, considering the importance of soil health from the perspective of environmental geochemistry, the presence and distribution of these elements in the region’s soil were investigated. The present study aimed to determine the distribution of heavy metals based on zoning maps of elements and the correlation between them in the soil environment.

For this purpose, the results of the chemical analysis of 61 soil samples were taken from a depth of 0-25 cm (after removing surface contaminants). The concentration of heavy metals was analyzed using the ICP-MS method in Zarazma Company and was evaluated and interpreted using multivariate statistical methods. Also, geoaccumulation index (Igeo), Nemerow integrated pollution index (NIPI), pollution index (PI), and enrichment factor (EF) of elements were calculated.

The average concentration of total heavy elements in the soils of the study area was 4.39, 13.34, 91.82, 32.18, 70.57, 11.70, and 81.64 for arsenic (As), cobalt (Cb), chromium (Cd), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn), respectively. The average concentration of heavy metals in the surface soil of Shahrekord for different elements was in the following order: As

Therefore, there is no significant environmental concern. This result is in line with the results of the present study. In all sampling sites, the PI is in the allowable category. Besides, the concentration of heavy metals such as Pb, Zn, and Cu is less in the soil of Shahrekord than in the soil of other cities, but Ni has a higher concentration. Also, since the EF was less than 10 for the study area’s soils, these elements’ natural or geogensis origin is confirmed