Description
Microplastics are pollutants that enter aquatic systems and primarily enter aquatic ecosystems through stormwater runoff. Microplastics are harmful after consumption and this study aims to highlight the particle behavior in an urban environment. By examining whether storm-drain outfalls along the Hampton University waterfront contribute microplastics to the Hampton River and whether particle abundance increases following rainfall events. Water samples were collected from four storm-drain sites along the university waterfront between October 2025 and January 2026, with collections occurring during or within 24 hours of rainfall events. Using size-fractionation, microplastics smaller than 500 µm were captured. For microplastic speciation, hydrogen peroxide digestion and Nile Red fluorescent staining were used for precise microplastic identification. Microplastics were detected at all four outfalls, indicating that storm drains transport plastics consistently from the land surrounding the watershed into the river. Abundance was relatively similar across sites, the average number of observations being 73.5, suggesting diffuse urban sources rather than a single dominant point source. Fibers were the most common microplastic type with 241 observations out of a total of 294, consistent with previous studies identifying textile fibers and tire wear particles as dominant contributors in urban environments. Fibers were all the same color on average. Black was 46.21% out of total microplastics observed, suggesting that their presence originated from a common source. The impermeability of each surface by site was 53.49 for site 1 and site 2, site 3: 26.57, site 4: 40.37, which are shown to have little impact on the total concentration of plastics. The strong correlation between the accumulation of plastics per collection day and the amount of rain shows a strong correlation, suggesting the amount of plastic is affected by the amount of rain. These findings highlight the role of stormwater systems in transporting land-based plastics to aquatic ecosystems and emphasize the importance of managing urban runoff to reduce microplastic pollution in estuarine environments.