Assessing Microplastic Pollution in Four Mile Run, an Urban Stream in Northern Virginia

Microplastics are pollutants of concern in waterways and oceans for their persistence and impact on aquatic life and food webs. This study demonstrates a low-cost land-based sampling method to assess the extent of microplastic pollution found in Four Mile Run, an urban stream in Northern Virginia. Microplastic particle counts in environmental and treated wastewater ranged from 0.01-0.24 particles L-1 (mean 0.08 particles L-1) and from 2 to 446 μg L-1 (mean 70 μg L-1), with fibers found to be the most common microplastic category. Treated wastewater effluent was found to be a significant source of microplastic pollution, though microplastics were also found upstream of any influence from wastewater or tide-borne materials. The sampling method proved effective for collecting and analyzing microplastic pollution, though the sample size of 100 L was deemed insufficient for reliable measurement of total mass of microplastics.