Handheld FT-IR spectroscopy for the triage of micro- And meso-sized plastics in the marine environment incorporating an accelerated weathering study and an aging estimation

Debris in the marine environment can be either natural, such as floating vegetation or volcanic ash deposits, or man-made. The man-made sources cover the whole gamut of material types, such as sewage, glass, mineral, fabric, and, of increasing concern, plastic or polymeric materials. Virtually all plastics absorb infrared (IR) light in a highly selective manner, making their infrared spectra a useful qualitative diagnostic. The triage of the visible micro- (~1 mm to 5 mm), meso-, macro- or mega-sized plastic particles with handheld Fourier Transform IR (FT-IR) enables rapid determination of the material on-site, and reduces time wasted on non-polymers on-site or at site. Four of the most prevalent neustonic plastic types, and their FT-IR spectral changes correlated with accelerated weathering, were successfully examined chronologically, detailing significant differences in aging profiles and chemical changes. Subsequently, a small spectroscopically identifiable degraded piece of plastic found in Greenland was correlated to the appropriate aging profile. Finally, a targeted methodology for quantification of submillimeter microplastic in dried estuarine sediment was evaluated to ascertain the potential limit of detection.