The effect of microplastics on soil evaporation dynamics and cracking morphology

Microplastic pollution in the environment has become recently a growing concern for soil ecosystems, affecting soil chemical and hydrophysical properties. The present study aims to analyse the effects of microplastics on water evaporation from soil samples and the cracking morphology induced by drying. In this regard, sandy and clayey soil mixed with two types of microplastics (Polyethylene and Polyvinylchloride) at concentrations ranging from 0 % to 4.5 % and 10% for evaporation and cracking experiments respectively. The samples were prepared under controlled laboratory conditions and placed in a climate chamber at constant relative humidity and ambient temperature. The result of the evaporation experiment reveals that the evaporation rate increases when soil is exposed to a lower concentration of MPs. Higher MPs concentration changes soil pore structure by clogging pores and affecting water transport, and thus the evaporation rate decreases. In addition, MPs with different concentrations in the cracking experiment change crack area, crack length, and pattern. The results from the experiments confirm that the concentration of microplastics as well as MPs physical and chemical characteristics significantly affect evaporation dynamics and cracking morphology in desiccating soils. Further work is necessary to study the effects of microplastics on different boundary conditions.