Presenter: Kaila Uyeda (Haverford College)

Description:
This study examines a large database of spectral measurements taken from macroplastic debris samples collected from two different coastal locations: Mumbai, India (135 samples); and Prince William Sound, Alaska (570 samples). Spectral data wes collected using an attenuated total reflectance - Fourier transform infrared spectrometer  (ATR-FTIR) and an x-ray fluorescence (XRF) spectrometer. Plastic debris collected from Mumbai originates primarily from the land proximal to the coastline whereas samples collected from Alaska have been transported through ocean waters from more remote locations prior to their deposition. The difference in transport in the environment of the two plastic debris sample sets presents an opportunity to compare the influence of environmental weathering on the accumulation and transport of metals and other elements on plastic surfaces. Environmental weathering processes alter the physical and chemical properties of plastic, changing plastic surface chemistry and the sorption of environmental contaminants including metals. The plastic debris samples, which include the six main plastic types, have been analyzed by ATR-FTIR to determine plastic type and evidence of weathering, and XRF to characterize metals and other elements present on the surface of plastic debris. Although changes in spectral features due to environmental weathering are dependent on plastic type, several key regions of the spectra have been determined to have changed when compared to unweathered consumer plastics. These key regions include those corresponding to hydroxyl groups, carbonyl groups, alkenes or carbon double bonds, and carbon-oxygen groups. Changes in these key spectral regions are compared to the elemental composition of the plastic debris as well as other features including density, thickness, and color to determine the relationship between weathering and the accumulation and potential transport of metals and other elements by plastic debris.