Microplastics in the sediment of Matagorda & San Antonio Bays: separation and identification

In the marine environment microplastics in surface waters are more easily accessible and analyzed, leaving those in the benthic environment relatively understudied due to the challenge in purifying the plastics from mineral and natural organic matter. In this study we validated a methodology using density separation to isolate plastics in marine sediment based on a set of homemade stainless-steel apparatus and lithium metatungstate solution. Using this method, we further obtained a baseline dataset of microplastics in surface sediments at 7 sites of Matagorda and San Antonio Bays, including polymer composition and potential spatial distribution patterns of the microplastics. FTIR results detected 17 different polymer types, as well as various rubber polymers. Multiple plastic morphology types were visually identified including disks, fibers, and fragments. the number of microplastics per gram of sediment was highest near a point source plastic plant near the Lavaca Ricer output. No other clear patterns were observed, suggesting the influence of currents or winds in the distribution of the sediment and microplastics.