Contamination and potential mobility assessment of potentially toxic elements (PTEs) in soils in relationship with...

Potentially Toxic Elements (PTEs) contamination in soils represents a significant concern for environmental health, agricultural productivity, and ecosystem sustainability. This study evaluates the impact of various environmental parameters, including elevation (1000-1500 m, 1500-2000 m, and 2000-2500 m), slope (0-20%, 20-40%, 40-60%, and > 60%), aspect (North, East, West, South, and Flat), land use (pasture, degraded forest, and forest), and erosion class (0-5, 5-12, 12-25, 25-60, and > 60 tons ha⁻¹ yr⁻¹) on the spatial distribution and potential mobility of PTEs (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) within the Çapakçur Microcatchment in Eastern Anatolia, Turkey. A total of 428 soil samples were collected from a depth of 0-20 cm using the grid method in the microcatchment, and the necessary analyses were performed for the study. Soil losses were figured out using the RUSLE method, and to assess for contamination, we used several measures: the Contamination Factor (CF), Enrichment Factor (EF), Geo-accumulation Index (Igeo), Pollution Load Index (PLI), and Modified Degree of Contamination (mCd) indices. The findings generally indicate low levels of PTEs content; however, slope and erosion play a determining role in the spatial distribution of metals, particularly Co, Zn, and Pb. The highest Cd and Co contents were detected in lands with a high slope (> 60%) and in forest areas. The Zn content was found to be higher in low-slope pasture areas. According to the CF and Igeo indices, the soils are mostly in the "lowly polluted" and "unpolluted" categories. However, the elements Co and Ni have reached "moderate contamination" and "significant enrichment" levels in some classes. The mCd values remained below the established contamination threshold of 1.5 defined in the mCd index classification, indicating a generally low degree of contamination across all groups. The results indicate that land topography and land use have significant effects on PTEs distribution in the soil. Specifically, slope and erosion directly impact metal mobility and bioavailability, making it crucial to consider these parameters for sustainable land management.