Marine plastic detection using PRISMA hyperspectral satellite imagery in a controlled environment

The amount of plastics on seawater is causing ecosystem damage both land areas and water bodies. It is proven that once plastic reach the sea, they will be degraded. As their detection is easy with in situ sampling, remote sensing techniques could detect and evaluate their impact on ecosystems. To under stand the main limitations of detecting floating plastic material remote images, an a pilot experiment was carried out on artificial floating plastic target deployed at the Aegean Sea (Greece) within the Plastic Litter Project 2021. Hyperspectral , multispectral PlanetScope and visible Unmanned Aerial (UAS) acquisitions were analysed. A nonlinear unmixing was applied to derive the spectral signature of the plastic ; finally, the linear unmixing approach allowed for determin ing the plastic percentage occupation at the pixel level. Different combinations of the PRISMA data were selected to evaluate provided the best result for the detection; one of these band was retrieved via the principal component analysis. slight differences were achieved using the different PRISMA -sets. As expected, since the artificial plastic target had diameter comparable with the PRISMA spatial resolution (~30 ), its detection was a challenging task caused by the water influ ence in the pixel (mixed pixels). The detection was realized by from the high amount of available spectral bands, as by the comparative test with a PlanetScope image used its original spatial resolution (3 m) and after degrading it at the level. Results demonstrated that an optimal target detec tion was possible with few spectral bands, only taking advantage of high spatial resolution (compared with the target dimension). , unreliable plastic fractions were derived at the PRISMA resolution with a limited number of spectral bands.