In order to reduce the quantity of microplastics (MPs) found in the environment, micro and nano plastics must be clearly and reproducibly identified. FTIR micro-spectroscopy is one method currently applied to classify MPs. Presently, the majority of MPs are identified as one of the common polymers: polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET). Therefore, the ability to uniquely link a given polymer with its source is challenging (if not impossible). A subset of MP samples was found to exhibit complex (multiple functional groups) spectra and could not readily be matched via infrared library database comparison to one polymer. Commercial plastics may be composed of copolymers; additives, fillers, dyes, etc. may be present. For this study, samples were collected from river bed sediments and water columns of the Raritan River in New Jersey. Samples were collected along transects up and downstream of major wastewater treatment facilities coinciding with long term macroinvertebrate water quality monitoring sites. The catchment includes a range of agricultural to urban land uses. Samples separated by size have been analyzed using Fourier Transform Infrared (FTIR). Samples close to 500 microns were analyzed using attenuated total reflectance (ATR) FTIR; MPs smaller than ~250 microns were analyzed via micro-spectroscopy. Polyesters, polyurethanes, polyamides as well as cellulose based polymers in MP samples have been tentatively identified. The challenge of identifying complex spectra of MPs will be discussed.

Identification of microplastics via FTIR micro-spectroscopy for potential source tracking in freshwater

2019 Spring National Meeting

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