Water Quality and Quantity - Pollution & Microplastics (Oral)

Polycyclic aromatic hydrocarbons (PAHs) are highly harmful environmental pollutant particularly relevant to waterways. These molecules have characteristic absorption and fluorescence spectra; however, their low effective concentrations makes their chemical sensing and quantitation challenging. We established that these hydrocarbons modulate the emission of the fluorescent moieties embedded in poly(fluorene) conjugated polymers to which we introduced variations in the conjugated core, as well as in the branches coming off the backbone. We focused on polymers including phenylbenzimidazole groups or polyethylene glycol chains as pendant chains. We showed that small PAH molecules quenched the fluorescence of these polymers based on an inner-filter effect whose effectiveness is characteristic of each PAH structure, thus making these polymers effective promiscuous sensors for these hydrocarbons. Indeed, we showed that the interaction patterns between these polymers and the "EPA 16" PAHs is sufficiently rich and nuanced that it contains sufficient information for chemical differentiation of these species.

The occurrence of microplastic (MP) pollution in consumer seafood is an increasingly studied and worrying circumstance. Microplastics have been found to negatively impact marine life that ingests them and filter feeding organisms and detritivores are particularly vulnerable. Compounding this, many of these species, like oysters, are foundational species, which provide a variety of valuable ecosystem services and are commercially and culturally significant in communities along the northern Gulf of Mexico (nGoM). Oysters are commonly used as bioindicators of water quality as they are susceptible to marine pollutants and changes in marine ecosystems. Our previous work on MPs in the Mississippi River Basin suggested that the Gulf of Mexico acts as a sink for MP pollution being funneled through the Mississippi River and that the marine life therein is exposed to relatively high levels of MPs compared to other coastlines. In ongoing research, we are analyzing both whole and dissected tissues (digestive tract, mantle, gills) of oysters sourced from multiple sites in the Mississippi Sound to evaluate both the concentration and types of MPs present. Furthermore, the dissection and analysis of individual tissues shows where the MPs accumulate within the oyster. The MPs are extracted and isolated using sample preparation methods newly developed in our laboratory and characterized using multiple techniques, including micro-Fourier Transform Infrared (µ-FTIR) and Laser Direct Infrared (LDIR) Imaging, which provide MP counts, morphologies, polymeric compositions, and sizes. This talk will include discussion of the methodology and preliminary data on the compartmentalization of MPs within Gulf Coast oysters and on the concentrations and characteristics of MPs at oyster reefs in the nGoM.

Research on the fate and uptake of plastic pollutants in tidal marsh ecosystems is sparse. In an attempt to quantify microplastic prevalence in tidal marsh ecosystems along the coast of Mississippi, we sampled marsh sediments and resident tidal marsh bird stomach contents within three marsh complexes along the Mississippi Coast. To investigate the availability of microplastic pollutants in the marsh habitat, we collected marsh sediment samples at 12 sampling locations within the marsh complexes. To investigate possible microplastic ingestion by resident tidal marsh birds, we captured Clapper Rails (Rallus crepitans) and Seaside Sparrows (Ammospiza maritima) near each sampling location and performed non-lethal stomach flushing to obtain a sample of their stomach contents. We used generalized linear models to differentiate microplastic counts in sediment and bird stomach samples among species, marsh complex, the distance from the Gulf of Mexico, and combinations of these variables. We detected microplastics in 64% of marsh sediment samples, 83% of Clapper Rail, and 69% of Seaside Sparrow stomach samples. The dominant types of microplastics detected in sediment and bird samples were fibers. Model selection showed random and highly variable microplastic concentrations in the tidal marsh sediments within and between marsh complexes. The top models for microplastic counts in marsh bird stomach samples included species and microplastics concentration in the nearby sediments. This study provides the first evidence of microplastic ingestion by resident tidal marsh birds and the first study of microplastic prevalence and distribution within tidal marshes along the Mississippi coast.

Marine microplastics (< 5 mm) pollution is a growing problem affecting coastal communities, marine ecosystems, aquatic and marine life, and human health. It is hard to escape news of debris of all kinds, and more specifically plastic debris of all sizes, in our oceans. Despite the growing awareness, data management of measurements of marine debris, from large size visual surveys along the coast and in the open ocean, to effects of microplastics on planktonic communities, lags far behind the needs of the scientific, education, and decision maker communities. This lack of large-scale, long-term, comprehensive data on microplastics makes it difficult to completely understand the sources, distribution and impacts of microplastics. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI), the nation’s environmental data steward, is spearheading efforts to make available global data on microplastics. NCEI is currently collating (micro)plastic data from across the world and inputting this into a database. The goal is to develop a one-stop repository where data on all types of marine debris and microplastics are aggregated, archived, and served in a consistent and reliable manner. This will establish NCEI as the primary location for marine debris data management. The database, when completed, hopes to contain extensive information on global microplastics. Together with other NCEI databases, such as the Global Ocean Current Database, World Ocean Database, and the Surface Underway Marine Database etc., researchers and interest groups will be able to access and assess data that will enable new insights in understanding of the global microplastic problems. The microplastic database will be freely accessible and will be maintained with newly received data from global users.