Comparative assessment of microplastic pollution in Terekhol and Sal estuaries, Goa, India

Abstract

Global concern regarding microplastics (MPs) has increased due to their potential risks. The primary source of microplastic contamination in the ocean is often terrestrial transfer from nearby locations. This study evaluated microplastic pollution in the Terekhol and Sal estuaries, found near their mouths, during the monsoon season of 2022. The size, shape, and colour of the MPs were determined using stereomicroscope, while Fourier-transform infrared (FTIR) analysis was used for polymer identification. The average concentration of MPs in the Terekhol and Sal estuaries were 0.25 particles/L and 0.30 particles/L, respectively, with the highest concentrations detected in the 5-1 mm size range in both estuaries. While fibres predominated in the Terekhol estuary and fragments were more common in the Sal estuary, white was the dominating colour in both estuaries. Polymer identification revealed the presence of polyethylene (PE), polypropylene (PP), and polyamide in both estuaries. The Pollution Load Index (PLI) values exceeded 1 indicated that both estuaries are contaminated with MPs. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis of MPs from both estuaries indicated varying levels of surface degradation and also the presence of various elements (C, O, Fe, Si, Ru, Cu, Co, Zn, Al, K, Na and Cl) on the surface of these MPs. These findings suggest that river inflows and fishing-related activities are likely the primary contributors to pollution caused by MPs in these estuaries.