Assessment of boron accumulation and pollution levels and their relation to soil classification

Because the thresholds for Boron (B) deficiency and toxicity in soils are very close, continuous monitoring of B levels is essential for sustainable soil and environmental management. This study aimed to determine total B concentrations in agricultural soils of the Seyhan Plain (Türkiye), evaluate associated environmental, ecological, and human health risks, and investigate the relationship between B concentrations and soil classification. A total of 51 surface soil samples were collected from conventionally managed cotton fields in the Seyhan Plain. Total B concentrations were determined by ICP-OES following microwave digestion. Pollution and ecological risk assessments were conducted using the enrichment factor (EF), contamination factor (Cf), geoaccumulation index (Igeo), and ecological risk factor (Er). Non-carcinogenic human health risks were evaluated separately for children and adults. Boron concentrations were also compared among different FAO-UNESCO soil classes. The mean B concentration in the studied soils was 43.72 mg/kg, which is approximately 2.6 t higher than the Upper Continental Crust (UCC) background value. The mean EF, Igeo, Cf, and Er values were 2.39, 0.73, 2.57, and 5.14, respectively, indicating moderate enrichment, moderate contamination, and low ecological risk. Human health risk assessment revealed that boron exposure through soil does not pose significant non-carcinogenic risks to either children or adults (HI < 1). Boron concentrations varied among soil classes, with the highest mean values observed in Gleyic Solonchak soils (50.72 mg kg^-1) and the lowest in Calcaric Fluvisols (41.96 mg kg^-1), although these differences were not statistically significant (Kruskal-Wallis, p = 0.123). The results suggest that both geogenic factors (parent material, soil characteristics, and drainage conditions) and anthropogenic factors (irrigation and agricultural practices) may have contributed to boron accumulation in the study area. Although ecological and human health risks were low, the observed boron enrichment highlights the importance of continued monitoring and site-specific management strategies for sustainable agricultural production in the Seyhan Plain.