Preliminary Analysis of Identifying Microplastic Polymers Using FTIR Spectroscopy from Surface Waters in the Pacific Northwest

Abstract

Microplastics (MP) are synthetic polymers < 5 mm in length. They have been found in a range of aquatic environments and inside the organs of human and aquatic species. There have been a number of studies surveying waterways for MP presence and abundance using microscopic analysis, however there is limited research findings on MP polymer identification. For this project, surface water samples were collected from 5 sites in the Pacific Northwest, extraction was done using wet peroxide oxidation, and Fourier Transformed Infrared (FTIR) spectroscopy was used to identify the polymers. Microplastics were found at all 5 sites, with the dominant polymer being polyethylene (> 65%), fragment was the most common morphology (> 74%), black was the most common color (≥ 33%), and the most common lengths were below 1 mm (>50%). Understanding the MP composition in surface waters can help direct policies related to reduction of plastic pollution in aquatic environments. Furthermore, knowing the chemical composition of polymers can help researchers understand how MPs influence the physiology and ecology of biota. Future research should investigate if spatiotemporal variables influence the results.