Assessment of the accumulation of selected trace elements in agricultural and non-agricultural soils using contamination indices: a case study from Kahramanmaraş (Türkiye)

Soil serves as the foundation of our food system. Therefore, consistent and reliable information about soil is essential for understanding, managing, and protecting it. This study examines the concentrations of trace elements of environmental importance, including vanadium (V), antimony (Sb), tungsten (W), thallium (Tl), and bismuth (Bi), in agricultural and non-agricultural areas in Kahramanmaraş (Türkiye) and evaluates their accumulation levels using contamination indices (i.e., enrichment factor (EF) and contamination factor (CF)). For this purpose, a total of 100 soil samples were collected randomly, including 64 samples from agricultural areas (32 from the upper depth and 32 from the lower depth) and 36 samples from non-agricultural areas (18 from the upper depth and 18 from the lower depth). The total concentrations of V, Sb, W, Tl, and Bi in the collected soil samples were determined. In non-agricultural soils (0–30 cm), the average concentrations of V, Sb, W, Tl, and Bi were 160 mg kg− 1, 0.90 mg kg− 1, 6.01 mg kg− 1, 0.78 mg kg− 1, and 0.55 mg kg− 1, respectively. Except for W, the trace element concentrations generally reflected the parent material. No pollution was detected in non-agricultural areas based on EF and CF results. In agricultural soils (0–30 cm), the average concentrations of V, Sb, W, Tl, and Bi were 111 mg kg− 1, 0.91 mg kg− 1, 7.16 mg kg− 1, 0.77 mg kg− 1, and 0.55 mg kg− 1, respectively. According to the pollution index results, V showed substantial enrichment in agricultural soils (average EF: 7.88; average CF: 6.81), whereas the other elements (Sb, W, Tl, and Bi) had EF values below 2 and CF values around 1. The accumulation of V in agricultural soils was associated with the excessive use of agricultural chemicals, particularly phosphorus-based fertilizers and pesticides. PCA and independent-sample t-tests indicated no statistically significant differences between agricultural and non-agricultural soils (p > 0.05), although EF and CF indices revealed substantial enrichment of V in agricultural soils.