This study provides baseline information for environmental assessment in North Riyadh, Saudi Arabia. It assessed the concentrations of eight heavy metals, namely cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn), in 28 surface soil samples collected across the area. Pollution status was evaluated using the contamination factor (CF), geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI), and degree of contamination (DC), while Pearson correlation, principal component analysis (PCA), and standardized hierarchical cluster analysis (HCA) were applied to identify the possible sources of these metals. Iron was the most abundant element (mean 8482.14 mg kg−1), consistent with its role as a major crustal constituent. Co, Cr, Fe, Ni, and V showed low contamination (CF < 1) and a predominantly geogenic origin, reflected in strong inter-element correlations and a dominant rotated principal component explaining 54.8% of the total variance; Cu, Pb, and, in particular, Zn departed from this pattern, loading together on a distinct secondary component (32.1% of variance) and showing localized enrichment at a small number of sites. None of the 28 samples exceeded the pollution threshold for PLI (all < 1) or DC (all < 8), indicating that the soils of North Riyadh remain overall unpolluted with respect to these eight metals. These findings provide an early geochemical baseline for the district and identify Cu–Pb–Zn enrichment near construction and traffic corridors.
A. El-Sorogy, Saad S. Alarifi, K. Al-Kahtany et al.· Land· 0 citations
Agricultural soils in arid regions require assessment approaches that separate local element enrichment from actual ecological and human health relevance. Here, a site-prioritization framework is applied to potentially toxic elements (PTEs) in agricultural soils from Onaizah, central Saudi Arabia. The approach combines contamination indices, ecological-risk screening, deterministic health-risk estimates, Monte Carlo resampling, and relative ranking of management priorities. A total of 33 surface-soil samples collected from cultivated farms were examined for As, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn. The measured concentration ranges (mg/kg) were 1–5 (As), 1–12 (Co), 10–53 (Cr), 4–38 (Cu), 107–541 (Mn), 6–54 (Ni), 2–23 (Pb), 8–47 (V), and 11–168 (Zn). Based on their mean concentrations, the investigated elements decreased in the following sequence: Mn > Zn > Cr > Ni > V > Cu > Pb > Co > As. The PN values ranged from 0.127 to 1.339, indicating 27 safe sites, 2 warning-line sites, and 4 slightly polluted sites, mainly controlled by localized Zn enrichment and, in one case, Pb. In contrast, mCd values of 0.099–0.676 indicated nil to very low contamination, while RI values of 2.743–15.701 confirmed low ecological risk across all samples. Non-carcinogenic risk was generally below the threshold of concern, with HI values of 0.204–1.018 for children and 0.024–0.119 for adults. Only one site showed a marginal child HI exceedance, emphasizing localized rather than widespread health concern. Children showed approximately 8.6-fold higher non-carcinogenic risk than adults, with Mn, Cr, As, and V as the main contributors. The total LCR values for As, Cr, and Pb ranged from 7.79 × 10−6 to 4.07 × 10−5 for children and from 3.48 × 10−6 to 1.82 × 10−5 for adults, within the commonly tolerable range of 1 × 10−6 to 1 × 10−4. Chromium was the dominant contributor to LCR. Monte Carlo resampling supported the deterministic risk classification, with only a 3.1% probability of child HI exceeding 1 and no simulated exceedance of the LCR threshold for either children or adults. From the standpoint of sustainable soil management, site 7 should undergo further health-risk assessment, while sites 30 and 33 require source verification and periodic monitoring before any remediation action is considered.
A. El-Sorogy, Talal Alharbi, Naji Rikan et al.· Sustainability· 0 citations
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