Study of Soil Pollutants in the Chahar Asyab Selected Regions, Kabul, Afghanistan

Abstract

Chahar Asyab District, one of the most densely populated areas of Kabul, Afghanistan, has faced decades of armed conflict, leaving substantial quantities of military debris, metallic fragments, and other hazardous residues in the environment. Weathering, oxidation, and corrosion of these remnants release potentially toxic elements (PTEs), including heavy metals, into the surrounding soils. The accumulation of these contaminants poses significant environmental and public health concerns, particularly for vulnerable populations such as children and the elderly, due to prolonged exposure through soil, water, and airborne dust. The district comprises extensive agricultural lands that rely on irrigation, creating pathways for contaminant mobilization and transport into the soil profile and groundwater. Irrigation water can enhance the leaching of toxic elements, increasing their bioavailability and the potential for uptake by crops. Consequently, contaminated soils may become a source of human exposure through the food chain and direct contact. During the dry season, from late spring to mid-autumn, wind readily entrains contaminated surface sediments from rivers, irrigation canals, and exposed soils, generating dust rich in potentially toxic elements. Atmospheric transport redistributes these particles over varying distances, depending on particle size, density, and meteorological conditions, thereby expanding the spatial extent of contamination. In contrast, precipitation during the wet seasons (winter and spring) removes airborne particles through wet deposition, returning contaminants to the soil surface. We show that subsequent infiltration, leaching, ion exchange, and mineral weathering govern the vertical migration and redistribution of these elements within the soil profile, thereby altering soil physicochemical properties, including pH, cation exchange capacity, and elemental mobility. Understanding the environmental behavior of potentially toxic elements in Chahar  Asyab is essential for assessing ecological and human health risks, protecting groundwater and agricultural resources, and developing effective remediation and sustainable land management strategies in post-conflict environments.