Microplastics and their effects on soil function as a life-supporting System

Particles play important roles in terrestrial systems, where the natural soil environment provides a complex habitat in which the three-dimensional organization of mineral and organic matter is combined to a diverse array of water levels, microscopic life forms, and their metabolites. Soils are the foundation for most land-based life and terrestrial ecosystem services that benefit humans. When plastics arrive at the soil, their nonnatural structure, distinct chemical composition, and unique surface properties trigger a series of abrupt environmental changes in the soil. Indeed, the current evidence suggests changes in the fundamental physical, chemical, and microbiological properties of the soils. Consequently, water and other biogeochemical cycles, as well as plant performance and animal health, can be affected. In this chapter, we present the recent advances in understanding how microplastics can change elementary properties of soil systems, such as soil aggregation and structure. This is discussed jointly with the linked effects in the microbial activity and function. Then, we address the recent studies regarding the effects of micro- and nanoplastics on plants and animals. Finally, we elaborate the properties of the various types of microplastics, soil processes, and soil organisms that are probably influencing the observed effects. We conclude by highlighting that current scientific information is not enough to devise solid risk assessments on microplastics in soils and suggest research directions to fulfill this gap