Identification and Quantification of Microplastics in a Tropical River System

Abstract

Microplastics (MPs), particles smaller than 5 mm resulting from the breakdown of plastic, pose a significant environmental threat, particularly in water bodies. This study focuses on the Bharathappuzha River in Kerala, India, to understand the transport of MPs within the river system. The objectives were to identify microplastic types and abundance, trace their origins, and analyse factors influencing their distribution from source areas to downstream locations. Advance techniques including Fluorescence Microscopy, Raman Spectroscopy, Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Grain Size Analysis were employed to analyse river water samples from 52 locations along the 209 km river course. Results revealed an average of 62 MP particles/lt of water and 2197 particles/kg of sediment, primarily comprising pellet granule beads (PGBs) shapes (83% in water, 77% in sediment). Sediment analysis indicated clay-sized particles were prevalent, consistent with typical deposition patterns. High levels of metals such as Ni and Cd detected via ICP-MS, might be considered potential sources including agricultural runoff containing fertilizers, pesticides, and quarry practices. This study provides crucial insights into microplastic pollution in a significant tropical river ecosystem like Bharathappuzha, highlighting the imperative for targeted measures to mitigate microplastic inputs from industrial, agricultural, and waste management sources along the river trajectory.