Microplastic abundance and heavy metal contamination in agricultural soil with the wastewater treatment plants effluent; Tehran, Iran

The study in Rey County, Tehran, Iran, examined microplastics (MPs) and heavy metals (Pb, Cd, Cu) in agricultural soils. Results show microplastic quantities (29–270 items kg⁻¹), predominantly small particles (100–500 µm), black (42.70%) and white (40.5%) in color, with Polystyrene (PS) and Polypropylene (PP) as dominant polymers from plastic mulches. Soil concentrations of Pb, Cu, and Cd averaged 30.41 mg kg⁻¹, 23.02 mg kg⁻¹, and 4.97 mg kg⁻¹, respectively. Microplastic-AES analysis detected Cu (5.86 mg kg⁻¹), Cd (3.45 mg kg⁻¹). Agricultural activities, especially plastic mulches, contribute significantly to soil contamination, emphasizing the need for sustainable practices in the region.