Claire Coutris
Research Scientist
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CVBiography
Research Scientist in environmental chemistry and ecotoxicology, with a focus on soil. Researches the fate, exposure, effects and risk assessment of contaminants in terrestrial environments, with expertise spanning metals, organic contaminants, pesticides, veterinary pharmaceuticals, plastics and other emerging contaminants. Combines laboratory studies, field research and environmental monitoring to support sustainable management of soils and circular bioresources.
Abstract
Plastic mulch films are widely used in agriculture, often in combination with pesticide application. While biodegradable plastic mulch films (BDM) are designed for soil incorporation, their influence on pesticide fate remains poorly understood. We investigated the influence of BDM on the degradation kinetics of four widely used pesticides (boscalid, pyraclostrobin, fluopyram and pyraflufen ethyl) in two agricultural soils under controlled conditions. Pesticides were applied at agronomically relevant doses either directly to soil or adsorbed onto a commercially available PBAT-starch BDM prior to soil incorporation, and pesticides and their relevant metabolites were monitored for 112 days. Adsorption to BDM significantly slowed pesticide degradation for all compounds, increasing degradation half-life DT50 values by factors of 2-26 compared with direct soil application. While degradation pathways were not fundamentally altered, the presence of mulch delayed metabolite formation and prolonged pesticide persistence. Rapid degradation of pyraflufen ethyl led to the accumulation of pyraflufen-ethyl metabolite E 3, a highly persistent multi halogenated metabolite that remains analytically and regulatorily overlooked. BDM itself showed limited mass loss (12 %) over the experimental period, suggesting that pesticide-plastic interactions can persist over environmentally relevant timescales. Overall, this study identifies plastic mulch residues as overlooked modifiers of pesticide persistence and metabolite accumulation in soil, suggesting that plastic-pesticide interactions warrant further consideration in environmental exposure and risk assessment frameworks.
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Claire CoutrisAbstract
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Authors
Claire CoutrisAbstract
Recovering and recycling agricultural mulch films can be costly and difficult because the plastics are often contaminated with soil, plant and pesticide residues. Biodegradable mulch films offer a potential alternative, but what happens when they are left in the field? Using examples from Norwegian field and laboratory studies, this presentation will explore how biodegradable mulch films degrade in soil, how they interact with pesticides, and what this means for the use of agricultural plastics in a circular economy. This session will provide a basis for discussion among project partners on experiences with biodegradable and conventional mulch films across different agricultural, environmental and waste-management contexts.