Heavy Metal Contamination in Arid Coastal Saudi Arabia: An Integrated Pollution-Index and Multivariate Approach Toward Environmental Sustainability

Abstract

Potentially Toxic Elements (PTEs) contamination of the soil is a global environmental problem, which can seriously affect the ecosystem, agricultural development, and human health. To evaluate the degree of potentially toxic metal contamination, 32 soil samples were collected from different sites in the Yanbu and Khulais areas of Saudi Arabia to analyze eight PTEs (Co, Cr, Cu, Fe, Ni, Pb, V, and Zn). The contamination indices used including the Geo-accumulation Index (Igeo), Enrichment Factor (EF), Contamination Factor (CF), and Pollution Load Index (PLI), as well as Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) for source identification. Because metals taken up from soil can move along the soil-to-plant pathway into crops, characterizing the degree and likely origin of potentially toxic metal enrichment in agricultural soil is a necessary first step for any subsequent land-management or food-safety assessment, particularly in a country that imports the majority of its food. The results of PCA and HCA indicate that the basement rocks of Arabian Shield-associated minerals are a plausible primary source of these potentially toxic elements. The mean EF values of the PTEs in decreasing order are as follows: Co (0.93) > Ni (0.92) > Cu (0.80) > Zn (0.74) > V (0.65) > Cr (0.59) > Pb (0.27). This implies that the soils in the study area are not enriched or only slightly enriched with PTEs. According to the geoaccumulation index values, nearly every PTE was classified as practically unpolluted (Igeo < 0), the exception being Ni, which reached the unpolluted-to-moderately-polluted class (Igeo ≥ 0) at four Khulais sites. The CF and PLI values indicate that the soil is unpolluted on average. In summary, the combined pollution-index and multivariate framework offers a practical geochemical screening tool for this arid coastal region; monitoring soil quality in this way is a useful contribution to sustainable land management in water- and land-limited environments.