Geochemical Baseline and Pre-Mining Environmental Assessment of Heavy Metals at Iron Exploration Area, Northeastern Aswan, Egypt

Abstract

Wadi Abu Subeira area contains many farms and houses and is one of the promising areas for iron mining. Therefore, 21 surface soil samples were collected and investigated for toxic heavy metals (Pb, Cr, Ni, Cu, Zn, Co, and As) using inductively coupled plasma (ICP) to establish a geochemical baseline for these metals during pre-mining conditions. To decipher the sources of these metals and their interrelationships, multivariate statistical analysis was applied, while to evaluate the degree of pollution and potential environmental risks the environmental indices were used. Abundances of Pb, Cr, Ni, Cu, Zn, Co, and As fluctuated from 17.72 to 0.06, 47.12 to 10.86, 47.88 to 9.25, 45.04 to 6.23, 51.93 to 17.82, 10.55 to 1.24, and 7.04 to 1.66 mg/kg, respectively, displaying a declining trend of Zn > Cr > Ni > Cu > As > Co > Pb. Additionally, the mean concentrations of all studied metals were found to be significantly lower than the selected international reference standards. Pearson correlation coefficient, principal component analysis, and cluster analysis revealed two geogenic geochemical associations for the studied toxic elements: (1) Zn-As-Ni-Cr-Cu-Co; and (2) Pb. Negative Igeo values were observed for all metals, which showed that the samples were uncontaminated and can be considered a geochemical baseline for the study area. Moreover, all CF values were lower than or close to 1, suggesting low contamination levels from all studied metals and supporting the association with natural geological processes. Similarly, Er and RI values of all metals were below 40 and 150, respectively, indicating a low-risk environment. Ultimately, the obtained levels of the studied metals can be used as a geochemical baseline for tracking the future changes in their accumulations in soil sediments considering the current assessment of the area as an environmentally safe area.