How microplastics affect soil structure

Plastic pollution is increasingly recognised as an enormous environmental and societal problem. Microplastic (< 5 mm) input to soils is estimated to be 40 times larger than input to surface waters. MPs accumulate in agricultural soils due to plastic mulching and application of polluted organic amendments such as sewage sludge and compost. Evidence on how microplastics affect soil hydrological and physical properties is limited and contradictory, while this can greatly affect the soil structure, soil water balance, infiltration and water holding capacity, in turn affecting runoff generation and erosion on sloping land. While soil erosion is the most common land degradation problem worldwide, how MPs are transported with runoff and erosion is virtually unknown. My research focusses on the effects of microplastics on soil hydrology using multiple laboratory experiments and modelling. I will work closely with a fellow PhD-candidate, who will focus on quantifying microplastic transport with runoff and erosion using rainfall simulation experiments, field monitoring and modelling. My research consists of the following steps: 1. Investigate and quantify how microplastics influence the formation and stability of soil aggregates 2. Unravel how this soil structure formation, under influence of microplastics, changes soil hydro-physical properties 3. Quantify the effects of microplastics on the soil water balance dynamics 4. Simulate soil water dynamics under changing rainfall regimes as affected by microplastics The research outcomes will greatly contribute to our knowledge on MP effects on soil hydro-physics.