Characterization of plastic litter along sandy beaches by hyperspectral imaging coupled with chemometrics

The present study aims to characterize plastic litter, collected along different sandy beaches of Japan, Chile, Portugal and Norway, by hyperspectral imaging (HSI) operating in the short-wave infrared wavelength range (SWIR: 1000- 2500 nm). This system was coupled with chemometric methods, such as Principal Component Analysis (PCA), to perform an exploratory data analysis, and a Partial Least Square – Discriminant Analysis (PLS-DA) to obtain polymer classification. Differences in composition and abundance of plastic waste were observed among the sampling sites. The results showed that the most contaminated site, in terms of plastic litter abundance, is Japan followed by Chile, Norway and Portugal. Results also showed that the main plastic categories are foam (87%), fragments (10%) pellets (2%) and fibers (1%). The main polymers found are EPS (88%), PE (7%) and PP (5%). EPS was sampled on 83% of beaches in Japan and on all beaches in Chile, whereas was not detected in European beaches (Norway and Portugal). This work confirms that HSI can represent a good solution for environmental monitoring of marine plastics (from megaplastic to microplastic size) in a fast, non-invasive and non-destructive way and can contribute to the challenge of environmental sustainability and to the achievement of the Sustainable Development Goals (SDGs) of UN AGENDA 2030, such as SDG14 (Life Below Water) and SDG15 (Life on Land).