Hyperspectral ultraviolet to shortwave infrared characteristics of marine-harvested, washed ashore and virgin plastics

Abstract. Combating the imminent environmental problems associated with plastic litter requires a synergy of monitoring strategies, clean-up efforts, policymaking and interdisciplinary scientific research. Lately, remote sensing technologies have been evolving into a complementary environmental monitoring approach that might have future applications in the operational detection and tracking of plastic litter at repeated intervals covering wide geo-spatial areas. We therefore present a dataset of spectral reflectance measurements from the ultraviolet (350 nm) to shortwave infrared (2500 nm) of synthetic hydrocarbons (plastics). Spectral reflectance of wet and dry marine-harvested, washed ashore and virgin plastics was measured outdoors with a hyperspectral spectroradiometer. Samples were harvested from the major accumulation zones in the Atlantic and Pacific ocean suggesting a near representation of plastic litter in global oceans. We determined a representative bulk average spectral reflectance for the dry marine-harvested microplastics and identified common absorption features at ~ 931, 1215, 1417 and 1732 nm, dataset available at https://doi.org/10.21232/jyxq-1m66 (Garaba and Dierssen, 2019a). Similar absorption features were identified in the dry samples of washed ashore plastics, dataset available at https://doi.org/10.21232/ex5j-0z25 (Garaba and Dierssen, 2019b). The virgin pellets samples consisted of eleven polymer types typically found in floating aquatic plastic litter, dataset available at https://doi.org/10.21232/C27H34 (Garaba and Dierssen, 2017). Magnitude and shape features of the spectral reflectance collected were also evaluated for two scenarios involving dry and wet marine-harvested microplastics, dataset available at https://doi.org/10.21232/r7gg-yv83 (Garaba and Dierssen, 2019c). Reflectance of wet marine-harvested microplastics was noted to be lower in magnitude but had similar spectral shape to the one of dry marine-harvested microplastics. In addition, we include metrics for microplastic particle morphology including sphericity and roundness. These open-access datasets will be useful in radiative transfer analyses exploring the effect of plastics to ocean colour remote sensing and developing algorithms applicable to remote detection of floating plastic litter. The dataset is expected to improve and expand the scientific evidence-based knowledge on optical characteristics of common plastics found in aquatic litter.