The use, fate and environmental impacts of plastic films in agriculture
摘要
Plastic agricultural films (PAFs) are widely used to enhance crop productivity, with global use projected to reach 9–14 million tonnes (Mt) per year by 2030. However, their use has led to contamination of soils with microplastics (MPs), nanoplastics and associated chemical additives. In this Review, we synthesize evidence on the global use of PAFs, their environmental fate and strategies to enhance their sustainable application. PAFs deliver substantial agronomic benefits, enhancing crop yields by 7–48% and soil water retention by 9–25%. However, films fragment and degrade under physical erosion, elevated ultraviolet radiation, temperature, humidity, and microbial and faunal activity. As a result, PAF use generates 3–5 Mt yr−1 of largely unmanaged waste, contributing to widespread plastic pollution in agricultural soils. For example, MP concentrations can reach ~13,000 items per kilogram, with PAFs accounting for 10–30%. Conventional polyethylene films degrade slowly and primarily undergo physical fragmentation, whereas biodegradable films fragment more rapidly, with cases of ~30% converted to MPs within 2 years. However, complete mineralization remains limited even for biodegradable materials. Additives in PAFs, including poorly characterized non-intentionally added substances, further increase environmental and toxicological risks, and their release varies substantially with environmental conditions and film type. MPs and additives affect soil health, crop yields and nutrient cycles. Mitigation strategies include substitution with safer additives, developing biodegradable waste-derived bio-based polymers, and conventional film recycling. Future work should improve field monitoring, develop a global database of PAF use and composition, and implement policy innovations to support sustainable PAF systems.