MICROPLASTIC AND MICROBEAD ABUNDANCE IN FRESHWATER SYSTEMS: A CASE STUDY OF THE ANACOSTIA AND PATUXENT RIVERS

Microplastics are solid plastic particles less than 5mm in size and are an emerging anthropogenic pollutant of concern because of their ubiquitous presence throughout the environment. Associated additives can leach into the environment from microplastics, potentially affecting the health of surrounding ecosystems. Sediments can serve as a final sink for microplastics, as such microplastics can be resuspended from sediments and transported in aquatic environments. Glass microbeads, another anthropogenic material, are used in road markings, and their presence in sediments could indicate road dust and run-off from roadways contamination in local ecosystems. Polycyclic aromatic hydrocarbons, or PAHs, are persistent organic pollutants associated with sediments and produced from burning fossil fuels or other anthropogenic sources. PAHs can enter the environment and pose a health risk to humans and ecosystems. The Anacostia River, located throughout the Washington, DC /Maryland region, has been historically polluted by anthropogenic contaminants such as trash, heavy metals, and sewage. The presence of microplastics, microbeads, and PAHs is not well documented nor considered in determining the health of the Anacostia River. The Patuxent River, located throughout central Maryland, is a tributary to the lower Chesapeake. The Jug Bay Wetlands Sanctuary, located in the lower Patuxent River, is home to various plant, aquatic life, and animal species. Microplastics and PAHs have not been studied in this area, and little is known about their presence in the Jug Bay Wetlands Sanctuary and the Patuxent River. In the Jug Bay Wetlands Sanctuary, Water samples were filtered and subsequently counted for the presence of any microplastics. Sediment samples were collected and analyzed for PAHs. Microplastic concentrations ranged from 4.81 MP/L to 6.60 MP/L in the sanctuary. In all sediment samples collected, no PAHs were detectable. In the Anacostia River Watershed samples analyzed, microplastics and glass microbeads were present in all sediment samples collected. The concentration of microplastics ranged from 0.041MP/g (41.1 MP/Kg) to 0.433 MP/g (433.9 MP/Kg). Glass microbead concentrations ranged from 0.051 MB/g (51.9 MB/Kg) to 5.00 MB/g (5,008.1 MB/Kg). Thermal Deposition and Pyrolysis GC/MS analyses have revealed several different contaminants to be adsorbed to the surface of microplastics and various polymer types across sample sites. PAHs were detected at every sample site except for one. A better understanding of their transportation to marine environments can be achieved by looking at the presence of microplastics in freshwater riverine environments.