RESULTS AND DISCUSSION
The method developed uses a binary solvent mixture of ethanol and water to separate POM from MP debris. Results and the underlying chemistry of this method are discussed below. A representative selection of the MPs isolated from POM in wrack line debris at sites in Lavaca Bay is shown in Figure 1. White blocky particles overwhelmingly dominated the samples collected. These atypical materials are released at this size and shape from a nearby industrial facility that produces pre-production plastics. However, note that there are also small plastics that typically dominate estuarine systems without an irresponsible industrial polluter. When viewed at 40x magnification, these typical materials have multiple colors, shapes, and sizes (Figure 1B1-4).
Isolated microplastics were quantified by mass rather than count due to their small size. MP constituted 2.62-21.3% (14.8 ± 7.1) of the POM sample mass and 0.04-0.42% w/v (0.2 ± 9.5) for the surface water. Peninsula Park (PL) had the highest concentrations of microplastics in both the beach POM and surface water at 196.6 ± 15.7 mg g-1 and 3.3 ± 1.0 mg L-1 respectively (Figure 2A). Six-mile (SM) beach had the lowest MP concentrations at 60.1 ± 29.6 mg g-1 and 0.7 ± 0.3 mg L-1 in the POM and surface water, respectively.