Microplastics in Bays along the Central Texas Coast

Estuarine and bay environments, which can act as sediment traps along the inner parts of continental shelves, may host significant depositional hotspots for plastic debris. This research targets Texas coastal bays (Matagorda and San Antonio), to better understand microplastic contamination in sediments and provide insight into the processes controlling its distribution. Microplastic extraction and quantification methods employed include sediment sieving, elutriation, microscopy, and spectroscopy. This study found low concentrations (ca. 10s-100s particles kilogram^-1 sediment or 20-200 × 10⁴ items meter^-3 wet sediment) and negligible correlations between analyzed deposit constituents (<i>R</i>² for grain size = -0.14 to 0.12, organic content = 0.08, water depth = -0.11, distance to shore = -0.14). The highly dynamic role of wind-driven mixing and openness to the Gulf of Mexico leads to the high flushing rate of sediment and microplastics out of the bays. Larger microplastic particles (fragments: 178 ± 93 μm, fibers: 0.5 to 2.0 mm) were consistently deposited with finer sediments, indicating high transportability. Microplastic resuspension into bay waters has significant implications for limiting microplastic accumulation within bay sediments. This work provides a baseline for future studies quantifying the roles of wind and residence time on microplastics in coastal environments.