Tracking additives fate from a biodegradable mulch film to soil: a comprehensive LC-MS investigation

Biodegradable mulch films (BMFs) are nowadays the alternative to conventional agricultural plastics for widespread cultivation all over the world. However, their long-term environmental impact, particularly concerning the behavior of embedded polymer additives (PAs) such as plasticizers, stabilizers, and antioxidants, remains poorly understood. These additives, not covalently bound to the polymer matrix, can leach into the soil during film degradation, potentially posing risks to ecosystems and human health. This study presents the first field burial investigation into the leaching and transformation of PAs from BMFs in a real-world context. A dual analytical approach was used: (i) targeted ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to quantify 15 representative additives and (ii) untargeted high-resolution mass spectrometry (HRMS) to identify transformation by-products. Analyses were performed on both BMFs and surrounding soils over different burial periods. Results show variable leaching behavior influenced by molecular weight, polarity, and polymer affinity. Notably, stabilizers like Irgafos 168 persist in microplastic fragments derived from BMF degradation, suggesting potential long-term accumulation in soil. In contrast, more polar additives such as tributyl-O-acetylcitrate exhibited vertical mobility. These findings provide crucial insights into the environmental fate of BMFs and support the need for improved risk assessment and regulatory strategies in agroecosystems.