Concentrations and transport pathways of microplastics in a coastal estuary

Plastics underpin modern human life, but its accumulation in natural environments poses a significant threat to biological organisms and foodwebs. Microplastics (<5 mm) represent the majority (>70%) of plastic emissions and act as important carriers of pollutants. This study combined measurements of microplastics in surface waters and microplastic settling behavior with a coupled hydrodynamic sediment wave model to study the transport of microplastics during normal conditions and an extreme storm event in Galveston Bay, Texas (USA). The Galveston Bay watershed is a major center of plastic production and shipping in the USA. Microplastics were identified and quantified by pyrolysis gas chromatography tandem mass spectrometry. This allowed the identification and quantification of microplastics at ultra-low levels (≥1 ng) without matrix interference. Settling behavior of microplastic aggregates was investigated with elutriation tubes that yielded information on settling velocities relative to microplastic content, composition, and association with organic and inorganic debris. Surface waters in Galveston Bay showed polypropylene (PP), polyvinyl chloride (PVC), nylon-66 (N66), polyethylene terephthalate (PET), and polyethylene (PE), with total concentrations ranging from 0.5-42.9 µg L^-1. The coupled hydrodynamic sediment wave model helped resolve the highly variable microplastic concentrations and compositions in the bay system. Additional parameterization of microplastic behavior in sediments will provide a better understanding of estuarine retention and export ability.

Presentation Preference: Poster

Primary Presenter: Karl Kaiser, Texas A&M University at Galveston (kaiserk@tamug.edu)

Authors:

Jiabi Du, Texas A&M University Galveston  (jdu@tamug.edu)

Kyeong Park, Texas A&M University Galveston  (parkk@tamug.edu)

Emily Summers, Texas A&M University Galveston  (emilyjane1215@tamu.edu)

Marcus Wharton, Texas A&M University Galveston  (mbwharton01@tamu.edu)

David Hala, Texas A&M University Galveston  (halad@tamug.edu)