Microplastic and potentially toxic element Co-contamination in semi-arid agricultural and peri-urban soils of Tamansourt (Marrakech Region, Morocco)

Microplastics (MPs) are an emerging soil contaminant, whereas potentially toxic elements (PTEs) are long-recognized persistent pollutants; their co-occurrence and potential interactions in terrestrial ecosystems are of growing concern. In semi-arid regions such as Marrakech (Morocco), where wastewater reuse and plastic-intensive agriculture are common, their accumulation in soils may pose long-term ecological risks. This study aimed to assess the occurrence, characteristics, and ecological implications of MPs and PTEs in agricultural and peri-urban soils of Tamansourt, on the outskirts of Marrakech, based on 30 soil samples collected from three sites across two depths. Soil samples representing different land uses and irrigation practices were analyzed for MPs using density separation, stereomicroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). Potentially toxic elements (Pb, Cd, Ni, Cu, Zn, and Co) were determined by acid digestion followed by Atomic Absorption Spectrometry (AAS). Microplastics were detected in all samples, with abundances ranging from 0 to 220 items kg⁻¹ dry weight, and significantly higher concentrations in surface soils (0–10 cm; mean = 64 items.kg⁻¹) than in subsurface layers (mean = 21.3 items.kg⁻¹; p < 0.05). Fragments dominated, with polyethylene and polypropylene as the main polymers. Potentially toxic elements showed moderate enrichment, especially Zn and Cu in peri-urban sites. Weak to moderate correlations were observed between MPs and Zn ( r ≈ 0.38) and Cu ( r ≈ 0.24). Pollution indices indicated unpolluted to moderately polluted conditions, while Cd contributed most to ecological risk. The co-occurrence of MPs and PTEs, concentrated in surface horizons of a rapidly expanding peri-urban agricultural zone, identifies Tamansourt as an early-stage but intensifying contamination hotspot. These baseline data establish a reference point for North African drylands and make a concrete case for embedding microplastics, alongside potentially toxic elements, into national soil-monitoring and wastewater-reuse standards before contamination becomes entrenched.