Mulch Films: Degradation Analysis and Ecotoxicological Assessment in Marine and Terrestrial Environments

Agricultural soils have been identified as significant sinks for plastic waste from mulch films, which in turn can reach aquatic ecosystems. As an alternative to conventional materials, there has been growing interest in biodegradable mulch films, but their environmental behavior and ecotoxicological effects are not yet fully established. In this study, the effects of residues from a conventional mulch film and a biodegradable mulch film on model organisms representative of edaphic (Hordeum vulgare and Cucurbita maxima) and aquatic (Paracentrotus lividus) ecosystems were evaluated. During this study, the residues of the mulches in seawater were also analyzed, considering natural aging conditions, using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). The results of the ecotoxicological tests showed that the residues of both types of mulch films did not generate any significant adverse effects on the selected terrestrial and marine bioindicators in the two end-of-life scenarios, with the exception of the residues of conventional mulch, unaged and aged for one month, at medium-high concentrations from an environmental point of view on P. lividus. The natural weathering assay in a marine environment showed that residues from conventional mulch film remained essentially unaltered, with similar concentrations detected throughout the 12-month exposure period. In contrast, the biodegradable mulch film exhibited significant degradation from the initial time point, reaching concentrations below the analytical detection limit after the first month.