Assessment of potential heavy metals in sediments of Arzhan Lake, Iran, using Kriging technique

This study investigates the concentrations, spatial distribution, and environmental impacts of potentially toxic elements (PTEs), including, As, Cd, Cr, Cu, Ni, Pb, S, and Zn—in the surface sediments of Arzhan Lake, Iran. Forty sediment samples were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Pollution indices, including the Contamination Factor (CF), Enrichment Factor (EF), Geo-accumulation Index (I_geo), Ecological Risk Index (ER), Toxicity Response Factor (TR), Integrated Pollution Index (IPI), and Nemerow Pollution Index (PI_Nemerow), were employed to assess contamination levels. Statistical analyses such as Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) facilitated geochemical interpretation, while Kriging interpolation was applied to map spatial distributions. Results indicated that the mean concentrations of all analyzed elements exceeded background values, based on local baselines, global averages, and Upper Continental Crust (UCC) levels to ensure contextual relevance. Cadmium (Cd) emerged as the most critical pollutant (CF = 3.35, EF = 10.89, I_geo = 1.16) and posed the greatest ecological risk (Er = 100.50). Arsenic (As), and S also showed elevated contamination levels. Spatial mapping of Arzhan Lake sediments using the Kriging method revealed hotspots of Cr and Ni in the northern part of the Lake, near agricultural areas, sulfur (S) and As in the central basin; and Cd in the southern part. These patterns highlight the roles of agricultural runoff, vehicular emissions, and natural depositional processes in controlling sediment contamination. The study’s limitations include the use of seasonal sampling, which may not fully capture temporal variability, and the presence of potential unmeasured pollutants. Additionally, the Kriging method assumes spatial stationarity, which may overlook micro-scale heterogeneity. Overall, sediments in Arzhan Lake exhibit moderate to considerable pollution and ecological risk (IPI = 1.86, RI = 144.36), underscoring the need for ongoing monitoring and targeted remediation.