Microplastic Pollution in Indiana’s White River: an Exploratory Study

Abstract

Plastic material is now a ubiquitous source of aquatic pollution. Microplastics, tiny plastic pieces often not visible to the naked eye, are a growing environmental concern in both marine and freshwater ecosystems. While many studies have documented the abundance and danger of microplastics in global oceans, little research is available on microplastic presence and impact in riverine ecosystems. This exploratory study aims to build on the findings of recent freshwater microplastic studies by reporting on the occurrence and types of microplastic pollution found in the West Fork White River in central Indiana. Fifteen surface water samples were collected from three bridge sites along the river over a four-month period (August - November 2015) and analyzed using established NOAA laboratory methods. Analysis revealed various microplastic particle types in the White River, with synthetic fibers being the predominant type collected. A total of 146 plastic pieces were collected across all sites and collection periods, with an average microplastic concentration of 0.71 items m^-3. Surprisingly, there were no significant differences in microplastic concentrations among sites of differing population density. Further, a local wastewater treatment plant had no effect on particle type or abundance. These findings contribute to current gaps in microplastic research on freshwater, especially fluvial, environments. This contribution may guide researchers in better understanding the extent to which these synthetic particles are polluting U.S. surface waters as a whole.