Impact of Microplastics on Soil Health: Soil-Water Retention, Shrinkage and Holding Properties

While microplastics in the ocean have been heavily studied, their impact on soils have not. Current research suggests microplastics are just as prevalent in freshwater and land as in the ocean and should be considered a pollutant due to the potential hazardous effects. Once in the soil, the chemicals in the plastics, or even the plastic particles themselves, can be taken up by plants. Understanding whether or not microplastics and their additives change the soil’s ability to retain water is a fundamental step towards determining the critical level of microplastics in cropland. This study reviews the effects of microplastics on the water retention and shrink/swell characteristics of soil and quantifies microplastics in the terrestrial environment. Samples were collected from the Texas A&M bioapplication field where sewage sludge has been applied, as sludge is a major vector of microplastics into soil. Samples were tested in the Pedostructure Characterization Lab for soil-water holding properties. Next, the amount of microplastics in the samples were quantified using gravimetric separation and sieving. No conclusive results about the impacts of microplastics on soil health could be drawn from this study. However, microplastics were found at a rate of 31,440 particles/kg at the bioapplication field, which is consistent with other studies quantifying microplastics in land with applied sludge.