Evaluation of heavy metal contamination and ecological risk of soil adjacent to Saravan municipal solid waste disposal site, Rasht, Iran

This study was performed on the soil of the Hyrcanian forests near Saravan municipal solid waste dumpsite, Rasht, Iran. In this research, the contents of metals (As, Pb, Cr, Cd, Cu, Hg, and Zn) were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The geoaccumulation index (I-geo), contamination factor (CF), and enrichment factor (EF), as well as pollution load index (PLI), were used to evaluate the metals contamination. The ecological risk factor (Eri) and the potential ecological risk index (PERI) were applied to assess ecological risk. Pearson's correlation coefficients and the principal component analysis (PCA) were used to determine the possible origin of the metals. The metal concentrations were as follows: Zn > Pb > Cu > Cr > As > Cd > Hg. The results of the statistical tests showed that, except for Cr, the other elements had a significant difference with the control station (P < 0.05). The results of the Pearson's correlation coefficients, the PCA, and the I-geo revealed that the possible source of As, Hg, and Pb was the waste dumpsite activities and other anthropogenic origins, while Cd, Cu, Zn, and Cr probably have geogenic sources. The PLI was < 1, in unpolluted grade for all stations. The Eri of the metals ranged as follows Hg > Cd > As > Pb > Zn, Cu > Cr, which implies that Cd and Hg play a key role in determining the ecological risk. The mean value of the PERI was 192.11 that represented a moderate ecological risk.