Abstract
The present study analyzes the physicochemical characteristics of microplastics (MPs) in agricultural soils within the district of Carabayllo, Lima-Peru. Soil samples were collected from three vegetable fields at three depth levels (0–10 cm, 10–20 cm, and 20–30 cm). Sample processing involved sieving (<2 mm), oxidative digestion (30% v/v H2O2), and density separation (5 M, NaCl). The results revealed MPs abundances ranging from 1178 to 1811 MPs/kg, with particle sizes spanning 3 to 5684.5 µm. The most frequently observed morphotypes were fibers, fragments, and films, while the predominant colours included black, blue, yellow, white, and transparent. Polyethylene, polypropylene, and propylene were identified as the primary polymer types. The physical and chemical characterization of MPs, coupled with their high concentration in irrigation water, suggests that MPs contamination in the study area primarily originates from the degradation of larger plastic materials. Potential sources include packaging waste, plastic bags, bottles, agricultural plastics, consumer products, textiles, and irrigation water. A statistically significant difference (p < 0.005) was observed between the three sampling depths, indicating a vertical migration of MPs from the surface to deeper soil layers (20–30 cm). This movement is likely facilitated by plowing and irrigation activities, which contribute to the redistribution of MPs within agricultural fields.
