Microplastics in French soil: from sources to consequences

The presence of microplastics (MP) in soils, from the most densely populated areas to the most remote one, is now well established. This contamination is the consequence of various human practices, such as the spreading of Organic Waste Products (OWP) or the use of plastic mulch. In France, studies working on MP in soil matrices have begun in the aim to increase our knowledge of the French situation. This paper will summarise the main findings of the MICROSOF, BIOMALEG and PRO projects. First, we will address the question of the MP contamination sources. OWP, used in agriculture, have been found to be almost systematically contaminated by MP, the abundance of which sometimes exceeds 105 MP/kg (dw). These results enabled to identify the production sectors and practices likely to generate or, on the contrary, limit the production of MP, as well as to estimate the flux of MP towards agricultural soils. Secondly, this presentation will focus on biodegradable film used in agriculture. The results of the BIOMALEG project have demonstrated that polymer films rapidly begin to degrade after burial. They also shed light on the duration of soil contamination by these MPs. Finally, we will provide an overview of the degree of contamination of French soils by MP, based on the latest results of the MICROSOF project, which relied on the Réseau de Mesures de la Qualité des sols (RMQS). The results point to contrasting levels of contamination in French soils, with agricultural soils harder affected than forest soils. Nevertheless, the levels measured suggest that the consequences remain limited at this point. Also see: https://micro2024.sciencesconf.org/558984/document