Cadmium-dominated potential ecological risk in agricultural topsoils of the Southern Çukurova–Adana Basin, Türkiye

Akyıldız M., Yıldız C. E.

Environmental Monitoring and Assessment, cilt.198, sa.1244, ss.1-10, 2026 (Hakemli Dergi)

Özet

Potentially toxic element accumulation in agricultural soils reflects interactions between farming activities and the geological characteristics of parent materials. Although the southern Çukurova–Adana Basin is one of Türkiye’s major agricultural regions, element enrichment and potential ecological risk have not previously been evaluated at the basin scale. In this study, pseudototal concentrations of Cd, Pb, Hg, Cr, Ni, Co and As were determined in 134 agricultural topsoil samples. Relative enrichment and potential ecological risk were assessed using the contamination factor (CF), geoaccumulation index (Igeo) and adapted Håkanson potential ecological risk framework, complemented by ordinary kriging, principal component analysis and hierarchical cluster analysis. Because a locally determined geochemical background was unavailable, upper continental crust values were used as a consistent reference framework. The Cd interpolation yielded a cross-validation RMSE of 1.74 mg kg⁻1. Cd was the most strongly enriched element, with mean CF, Igeo, and ecological risk factor (Eᵣⁿ) values of 61.22, 4.22 and 1836.67, respectively, accounting for 90.7% of the mean potential ecological risk index (RI). The basin-wide mean RI was 2025.21, corresponding to the conventional very high potential ecological risk category. Mean RI was highest in Tuzla (2627.21), followed by Doğankent (2342.77), and was substantially lower in Karataş (473.29). Spatial and multivariate results indicated overlapping potential external and lithogenic influences. Pronounced Cd enrichment was compatible with contributions from long-term agricultural inputs, with phosphate fertilizers representing a plausible pathway, whereas Ni and Co showed stronger associations with parent material composition. These findings provide a regional screening baseline for source verification, targeted environmental monitoring and sustainable soil management in intensively cultivated Mediterranean agroecosystems.