Potentially Toxic Element Contamination and Ecological Risk in Surface Sediments of the Khuzestan Plain, Southwestern Iran: A Province‑Wide Geochemical Baseline for a Major Middle Eastern Dust Hotspot

The Khuzestan Plain in southwestern Iran is a major dust source. This study presents the first province wide assessment of potentially toxic elements in 69 surface sediment samples. Mean concentrations (mg/kg) decreased in the order: Ti (2012), Mn (478), Ba (209), Ni (115), V (75), Cr (65), Zn (49), Co (25), Cu (20), Pb (20), As (6.7), Mo (3.1), Sn (1.7), Cd (0.6). Pronounced spatial variability (CV > 50%) for Ba, Mo, and As suggests localized anthropogenic sources, while As, Cd, Ni, and Mo exceed Upper Continental Crust values; Ni surpasses both TEL and PEL by factors of 7.2 and 2.7, respectively. A strongly correlated lithogenic cluster (Ti, Mn, Ni, V, Cr, Co, Sn) reflects bedrock weathering, whereas As, Ba, Mo, Pb, and Zn are decoupled from this assemblage, indicating anthropogenic inputs. Cadmium exhibits significant enrichment (EF = 11.6), pointing to dominant industrial sources, followed by As (EF = 8.8); Mo, Ni, Co, and Pb show moderate enrichment (EF = 4.6, 4.4, 2.8, and 2.5, respectively). Although mean contamination is low (mCd = 1.59), the potential ecological risk is moderate (RI = 241.8), with Cd contributing >70% of the total risk, while Ni drives the direct toxicological risk (TRI = 5.4).