Assessment of microplastic contamination in coastal surface waters: a case study of five beaches in South Goa, India

Abstract

Microplastics (MPs) have emerged as a pervasive environmental contaminant, posing significant threats to aquatic ecosystems. Coastal regions, which sustain rich biodiversity, are particularly vulnerable to pollution from human activities. This study investigates the spatial variations of MPs, their characteristics, polymer types, and the ecological risks they present in selected southern beaches of Goa, situated along the Southwest coast of India. MP concentrations in surface waters ranged from 0.17 to 2.51 MPs/L across individual stations, with an average abundance of 1.21 MPs/L, indicating notable spatial variation; average concentrations at each beach varied between 0.47 and 2.03 MPs/L. Fibres were the dominant MP shape, while colourless and white MPs were prevalent in all sampled surface waters along beaches. MPs sized between 1 and 5 mm were more common than those in the 0.3-1 mm range. Common polymer types identified through analysis included polyethylene, polypropylene, polystyrene, ethylene vinyl alcohol, and polyurethane. Scanning Electron Microscopy analysis showed varying degrees of surface degradation, indicating prolonged environmental exposure. Risk assessment revealed that the southern beaches are polluted with MPs, as indicated by a Pollution Load Index of 2.5 and a Pollution Hazard Index of greater than 1000, categorized as hazard level V. These indices provide valuable insights into the extent of MP contamination and its potential risks to the environment. Overall, this study offers critical baseline data on MP pollution in the coastal waters of south Goa beaches. The findings can serve as a foundation for future research on the ecotoxicological impacts of MPs on marine organisms and inform strategies for mitigating plastic pollution in these vulnerable ecosystems.