Beyond the greenhouse: The spread of plastic pollution from an intensively cultivated agricultural area

Among the many sources of plastic contamination, greenhouse agriculture is a major contributor due to its intensive use of plastic materials. This study examines plastic waste in one of the world's leading greenhouse farming regions. The research included both abiotic (soil, freshwater, seawater, and air) and biotic compartments (invertebrates, herbivores, fish and predators) as well as the presence of bacterial and fungal pathogens colonizing agricultural plastics. Plastics were identified in all sampled compartments, including the nearshore seawater. The highest concentrations were recorded along the coastline, where 1397 plastic items representing 15 different polymers were found with a median concentration of 1.92 (1.73–2.13) items/m² or 3.05 (2.29–3.81) g/m², the boundaries representing interquartile ranges. Most of the polymers identified across all compartments matched those found in agricultural operations in terms of morphology, type, and colour. Notably, high plastic concentration appeared in protected areas, indicating that legal protection alone does not prevent pollution. Greenhouse plastics were especially prevalent in the protected zones near the greenhouse area, rather than in the nearby urban zones, which can be explained by the proximity of agricultural exploitations. We estimated that approximately 290 kg of plastic, including 80 kg of polyethylene, were dispersed along the coast, a figure representing about one-tenth of the plastic waste generated annually in the production zone. Our results also revealed that agricultural plastic waste may act as vector and reservoir of bacterial and fungal pathogens, promoting their spread even into protected environments.