Microplastic profile and ecological risk assessment of emerging estuarine contaminants in two tourist hotspots of northern Kerala backwaters

Microplastics (MPs) are emerging environmental pollutant that poses a growing risk to the environment and human health, especially in sensitive estuarine systems. In this study, MPs pollution in the surface sediments and water of the Chandragiri and Kavvayi backwaters in northern Kerala, two ecologically sensitive and tourism-dominated estuarine systems are comparatively investigated. The abundance, distribution, morphology, and polymer composition of MPs were systematically analyzed. Sediment analysis revealed that sand was predominant in both estuaries, followed by silt and clay, with average MP concentrations of 187.2 particles/kg in Chandragiri and 259.2 particles/kg in Kavvayi. In the water samples, average of 284 and 251 particles/L, respectively. MPs were mainly categorized as fibers, fragments, filaments, and foam. Raman spectroscopy identified polyamide as the dominant polymer type in all samples. The risk assessment indicates a high ecological risk associated with MPs pollution, mainly caused by anthropogenic impacts such as tourism, fishing, and poor waste management. This study highlights the need for targeted mitigation strategies and improved policy interventions to address MPs pollution in the estuaries of Kerala.