Release of potentially toxic elements from an operational phosphate mine (Sebaiya east, Egypt): geochemical characterizations, environmental risks and mining sustainability

Abstract

Abstract The extraction and processing of naturally occurring phosphate deposits have significantly intensified the mobilization of potentially toxic elements (PTEs), resulting in their pervasive release into the environment. Accordingly, this study investigated the environmental impact of phosphate mining at Sebaiya East area (Egypt), analyzing 24 surface sediment samples for PTEs via ICP-OES, supported by statistical analysis (descriptive and multivariate), pollution indices (individual, composite, and ecological), and health risk assessments (carcinogenic and non-carcinogenic) to understand the release, distribution, accumulation, and geochemical behavior of contaminants. The median values of PTEs were lower than their maximum concentrations, highlighting localized hotspots. Cd’s average level consistently exceeded all geochemical reference values. The individual contamination grades, based on average I geo and CF values, ranked as Cd > As > Cr > Ni > Zn > Cu > Pb. Samples showed overall contamination (mean PLI: 1.79, mean C deg : 20.45, mean PI Nemerow : 4.29), with 29.2% severely polluted (PLI > 2) and 37.5% highly contaminated (C deg ≥ 24), localized near mining activities. The mean RI value of 383.9 indicated a considerable ecological risk (300 < RI < 600) throughout the study area. Weak Pearson correlations observed for As and Cd with other PTEs indicated distinct geochemical behavior and anthropogenic origins. PCA revealed the mixed origin of Pb, Cu, Zn, As, and Ni in PC1 (weathering of local bedrock and diffuse deposition from mining activities) and the anthropogenic origin of Cd in PC2. Cr and As posed the highest carcinogenic (CR: 3.64E + 02) and non-carcinogenic risks (HQ: 3.04E + 05), respectively, exceeding safety thresholds.