Plastics have revolutionized consumer goods, making things cheaper, quicker, and easier to obtain. From packaging to toys to kitchenware, plastics are now ubiquitous in modern society. However, this convenience comes with a cost.
Scientists have documented increasing evidence of the severity of plastics pollution. These range from ingestion of microplastic particles (<5 mm in size) by aquatic and terrestrial organisms (including humans) to being a transport mechanism for pathogens and other environmental contaminants. To date, most research has focused on microplastics in marine environments. Little research has examined microplastic transport and co-contaminant issues in terrestrial environments such as rural American farmland streams. This study was the first microplastics study of rural streams specifically conducted in Iowa and the nation.
To better understand these issues, researchers from the United States Geological Survey (USGS) and the University of Iowa conducted the first statewide assessment of microplastics in rural Iowa streams. They also investigated potential relationships between microplastics and other contaminants that are known to be present in Iowa streams. Assessment of these small, first-order streams revealed potential relationships between microplastics and representative land uses, laying a foundation for more informed management practices and helping us understand microplastic dynamics on agricultural lands that support the diets — and thus indirect exposure potential — of millions of people.
ISTC research chemists John Scott and Lee Green analyzed for microplastics in the samples collected for this study. They investigated wastewater treatment plant outputs such as effluent and residual solids (biosolids), amended/unamended soil samples, and surface waters near the test sites to identify the major sources of environmental microplastics, how these materials move in the environment, and their final fate.
Project partners are currently measuring other contaminants. While the evaluation of microplastic results is still in progress, preliminary findings show that agricultural sites have very high microplastic concentrations, and stream-bed sediments appear to be a major sink for this class of contaminants.
Funding for this research came from the Center for Health Effects of Environmental Contamination (CHEEC) at the University of Iowa and an in-kind contribution from the USGS. Final results are expected in summer 2023.