Exploring the theoretical effects of landfill based microplastic accumulation on the hydro-mechanical properties of porous soil media

In recent years, landfill has emerged as one of the major sources of MPs. The interaction of MPs with the porous soil media beneath landfill is not known. Therefore, through this minireview we make an attempt to explore the theoretical changes in soil hydro-mechanical properties of landfill liner material that are likely to be induced by MPs accumulation. The aim is two-fold: first, we review the current state of the art on characterization of MPs in landfill leachate based on its concentration, polymer type, morphology, and sampling conditions. Second, we discuss the changes in hydro-mechanical properties of porous media brought about by MPs accumulation by considering the changes in phase diagram, unsaturated soil properties and shear strength model. The possible changes in barrier clay due to MPs accumulation is discussed based on "diffused double layer theory", which include the negative changes that can be brought about by nano-plastics in engineered clay barriers. The last section briefly discusses some possible future research directions that could help in improving current design guidelines for landfill liner system.