Employing Environmental Risk Indicators for Evaluating Soil Contamination by Heavy Metals Near Landfill Sites in Babylon

Abstract

This study aims to assess soil contamination and investigate some chemical properties influencing the behavior of heavy metals resulting from waste dump residues. Contaminated and reference soil samples were selected from two sites and three transects, located between latitudes 32º34′58.15″–32º32′59.77″N and longitudes 44º31′36.93″–44º35′11.05″E in Babylon Governorate, Iraq.

The total concentrations of heavy metals (mg kg⁻¹) at sites S1 and S2 were 24.1 for lead (Pb), 2.62 for cadmium (Cd), and 186 for nickel (Ni), respectively. In the transect soil samples, Pb recorded 17.2, Cd 3.3, and Ni 127 mg kg⁻¹, while in the reference soils, concentrations were 14.0 for Pb, 3.17 for Cd, and 127 for Ni.

As for the chemical speciation of the studied metals, the distribution followed these patterns: •

Lead (Pb): Residual > Oxide and organic-bound > Carbonate-bound > Exchangeable •

  Cadmium (Cd): Residual > Oxide and organic-bound > Carbonate-bound > Exchangeable •

  Nickel (Ni): Residual > Carbonate-bound > Oxide and organic-bound > Exchangeable •

According to pollution index values, the potential ecological risk index (ER) ranged from low to moderate for all studied soils. The overall ecological risk index (RI) for the studied elements was within the low-risk category.

The geoaccumulation index (Igeo) values for the heavy metals indicated contamination levels ranging from “uncontaminated” to “moderately contaminated” across all soil samples in the study