College of Science and Engineering


Biology; Marine and Conservation Biology

Faculty Mentor

Peter J. Alaimo, PhD and W. Lindsay Whitlow, PhD

Faculty Editor

Mark Jordan, PhD

Student Editor

Ciara Murphy


Microplastics are widespread aquatic pollutants that contaminate waterways and originate from human sources, such as packaging or cosmetics. They are smaller than 5.0 mm and include both manufactured plastics (primary), or environmentally degraded plastics (secondary). Concerns about the potential impacts of microplastics through chemical pollutant adsorption, marine organism ingestion, and biomagnification indicate the importance of further investigation into the quantity and types of microplastics in the Puget Sound. Our initial visual analysis using light microscopy identified plastics in samples of both sediment and surface water. An improved plastic extraction method and chemical analysis procedure was developed. In this improved process, samples were filtered through a series of sieves and vacuum filters followed by an adapted enzymatic digestion using proteinase-K in SDS, then density separated using zinc chloride prior to ATR FT-IR analysis. Spectra from various locations were then analyzed to identify microplastic type. This purification method paired with ATR FT-IR analysis is an efficient method that avoids plastic degradation and bias of manual sorting, two known problems of previously published methods, and thus aids in the identification of microplastic contaminants. This allows for increased confidence when making comparisons between identified microplastics.