Development of soil pollution risk index in the vicinity of a waste dam in Chadormalu iron ore mine

Soil pollution caused by anthropogenic activities or natural factors results in reduced quality of environment. Fourteen elements, including Ti, Al, Fe, Cr, V, Pb, As, Sc, Zn, Cu, Co, Mn, Ca and Mo, in 20 soil samples and a wildflower called Anabasis Setifera on the tailing pond of Chadormalu iron ore in Iran were assessed. Metals were measured using inductively coupled plasma mass spectrometry (ICP-MS). Enrichment factor and contamination factor were employed to assess the ecological risk. C_fⁱ value within the range of 1.00–1.12 indicates the mean contamination of the soil, and E_rⁱ value within the range of 1–10 represents the low ecological risk of the elements in the soil. Transfer factor (Tr_i) was also used to calculate the transfer of heavy metals from soil to plant. Tr_i value within the range of 1.63–29.01 shows that the plant induces the transfer of contaminants from soil. The order of the transferred elements in terms of amount is as: Co > Ti > Cr > Al > Mn > Fe > Ca > V>Cu > Pb > Zn > As > Mo > Sc. Geo-accumulation (I_geo) and pollution indices have showed some weaknesses in assessing the high values of the elements. Therefore, in this study, a new index as level of pollution, Ln (LP), was developed to evaluate the contamination of soil by various concentrations of the elements. Based on I_geo and I_POLL, the pollutants fall within the class of 0 which indicates no pollution. The Ln (LP) index calculated as 0.069–1.166 shows that the studied elements, except for cobalt, had no pollution.