Exploratory Assessment of Heavy Metal Contamination in Wastewater Irrigated Vegetable Soils of Southern Tehran under Industrial Influence

This exploratory study assessed heavy metal contamination in wastewater-irrigated vegetable soils in southern Tehran, Iran, and examined its spatial relationship with wastewater canals and nearby industrial activities. Vegetable cultivation areas were delineated using multi-temporal Sentinel-۲ imagery, NDVI, field observations, and Support Vector Machine classification. Five composite surface-soil samples were collected from vegetable fields near wastewater conveyance canals and analyzed for Pb, Ni, Cd, Zn, and Cu using atomic absorption spectrophotometry. Exploratory Inverse Distance Weighting maps were generated to visualize possible spatial patterns in metal concentrations. Pb concentrations were above ۶۰ mg kg⁻¹ at three of the five sampling sites, while Cd concentrations were above ۳ mg kg⁻¹ at two sites. Zn showed the highest absolute concentrations among the analyzed elements, whereas Cd showed the lowest. The spatial correspondence between elevated metal concentrations, wastewater canals, and nearby industrial infrastructure suggests a possible anthropogenic contribution, although the limited sampling density does not allow definitive source attribution. The findings provide preliminary evidence of soil contamination in wastewater-dependent vegetable production areas and support the need for expanded soil and crop sampling and improved monitoring of wastewater and industrial discharges.

کلیدواژه ها:

heavy metals ، Soil contamination ، Wastewater irrigation ، Industrial effluents ، Peri-urban agriculture