Cadmium Drives Very High Ecological Risk in Çukurova–Adana Agricultural Soils

Cadmium has emerged as the dominant contaminant driving potential ecological risk in the agricultural topsoils of the southern Çukurova–Adana Basin, one of Türkiye’s most intensively farmed Mediterranean regions. That is the central finding of a new screening study published in Environmental Monitoring and Assessment, in which researchers Mustafa Akyıldız and Can Ekin Yıldız measured potentially toxic elements across 134 agricultural topsoil samples and evaluated their enrichment and risk at the scale of the whole basin. According to the authors, element enrichment and potential ecological risk had not previously been assessed at this basin scale, despite the region’s agricultural importance.

The team determined pseudototal concentrations of seven elements: cadmium, lead, mercury, chromium, nickel, cobalt and arsenic. Because a locally determined geochemical background was unavailable, they used upper continental crust values as a consistent reference framework. Relative enrichment was quantified with the contamination factor and the geoaccumulation index, while potential ecological risk was assessed with an adapted version of the Håkanson potential ecological risk framework. The spatial pattern of cadmium was mapped by ordinary kriging, and the statistical structure of the data was explored with principal component analysis and hierarchical cluster analysis. The cadmium interpolation achieved a cross-validation root mean square error of 1.74 milligrams per kilogram.

The results show cadmium standing apart from every other element measured. Its mean contamination factor was 61.22, its mean geoaccumulation index 4.22, and its mean ecological risk factor 1836.67. Cadmium alone accounted for 90.7 percent of the mean potential ecological risk index across the basin. That basin-wide mean index came to 2025.21, which corresponds to the conventional very high potential ecological risk category. In practical terms, the risk profile of the region’s agricultural topsoils is overwhelmingly a cadmium story rather than a multi-element contamination problem.

The spatial analysis revealed marked internal contrasts. The mean potential ecological risk index was highest in the Tuzla area at 2627.21, followed by Doğankent at 2342.77, while Karataş recorded a substantially lower mean of 473.29. These differences suggest that risk is not evenly distributed across the basin but concentrated in particular zones, which the authors argue could inform targeted environmental monitoring rather than uniform basin-wide interventions.

Interpreting the sources of contamination required care, and the study stops short of definitive attribution. Spatial and multivariate results indicated overlapping potential external and lithogenic influences, meaning that both human activity and the composition of the underlying parent materials appear to contribute to the observed pattern. Pronounced cadmium enrichment was compatible with contributions from long-term agricultural inputs, with phosphate fertilizers identified as a plausible pathway, since phosphate rock used in fertilizer production can carry cadmium as a natural impurity. Nickel and cobalt, by contrast, showed stronger associations with parent material composition, pointing to geogenic rather than agricultural origins.

The authors frame the work as a regional screening baseline rather than a final verdict on contamination sources. The findings are intended to support source verification, targeted environmental monitoring and sustainable soil management in intensively cultivated Mediterranean agroecosystems. Because the analysis relied on pseudototal concentrations and upper continental crust reference values in the absence of a local geochemical background, the results serve as a consistent comparative framework for the basin, with follow-up work needed to confirm specific sources and pathways on the ground.

For a major agricultural region that supplies Türkiye’s food production, the study highlights how decades of farming practice can leave a measurable signature in topsoil. The very high potential ecological risk category assigned to the basin mean, driven almost entirely by cadmium, underscores the scale of the accumulation suggested by the data. Whether that accumulation continues to rise, stabilizes or can be mitigated through fertilizer management and soil monitoring remains a question for the source-verification studies the researchers propose as the next step.

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

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

Article References: Akyıldız, M., & Yıldız, C. E. (2026). Cadmium-dominated potential ecological risk in agricultural topsoils of the Southern Çukurova–Adana Basin, Türkiye. Environmental Monitoring and Assessment, 198(11), Article 1244. https://doi.org/10.1007/s10661-026-16037-y

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16037-y

Keywords: cadmium, soil contamination, agriculture, heavy metals, Türkiye, ecological risk, environmental monitoring, Cadmium-dominated, potential, ecological, risk, agricultural