Floating Microplastics in Northern Coastal Waters of Sri Lanka: Quanti cation and Characterization by FTIR

Abstract

Microplastic (MP) pollution is a growing issue in Sri Lanka. However, few ndings have been reported in the Northern coastal belt of Sri Lanka. This study provides the rst evidence of the prevalence and abundance of MPs in the Northern Sri Lankan coastal waters of Mathagal, Point Pedro and Charty Beach in Ja na. Floating MPs were collected using a plankton net with a mesh size of 153 m horizontally at the surface once a month from August 2020 to January 2022. The MPs were characterized based on their physical morphology; size, shape and colour by stereo microscope and chemical composition by Fourier transform infrared spectroscopy (FTIR). MPs (1-5 mm) were found in each site studied. The MP abundance was signi cantly varied both spatially and temporally (p< 0.05). The overall mean MP concentration was 1.40 1.12 items m-3 with values of 1.31 1.39 items m-3, 2.34 2.5 items m-3 and 0.56 0.81 items m-3, at Mathagal, Point Pedro and Charty Beach respectively. MPs with a diameter of 2-4 mm (64%) predominated. The investigation discovered that the three most prevalent shapes in the overall abundance were lms (31%), fragments (26%) and bers (16%). White MPs were shown to be the most widespread (47%), followed by blue (28%) and green (16%). The FTIR analysis revealed that polyethylene (59%) was the most abundant polymer type, followed by polypropylene (27%). Land based sources, including shing and recreational activities were identi ed as a major contributing source of pollution in the studied coastal environment.