Microplastic pollution and textural characteristics of sediments in a tropical reservoir, Kerala, India.

Microplastic pollution is now recognised as a severe environmental issue affecting aquatic habitats. Although initially buoyant, microplastics can undergo vertical transport through the water column, eventually settling and accumulating in benthic sediments. The goal of this research is to evaluate microplastic pollution in the benthic sediments of a tropical reservoir, Aruvikkara, one of the primary water sources in Kerala, South India. This study also evaluates sediment texture as a primary determinant of microplastic retention in benthic layers. Identification of microplastic polymers in reservoir sediments was carried out using FTIR/Raman spectroscopy, and the Pollution Load Index (PLI), Polymer Hazard Index (PHI), and Potential Ecological Risk Index (PERI) were calculated. The reservoir is categorised as 'High-Risk' and 'Hazard Level III' due to its critical poly vinyl chloride levels. Municipal waste dumping and other human activities can be correlated with microplastic contamination in the reservoir. The textural analysis of the reservoir sediment revealed that it is silty clay, which contributes to microplastic accumulation and retention. The study reveals that reservoir sediments can act as sinks for microplastics. These results mandate stringent municipal waste management and reservoir protection measures to restrict the reservoir contamination and safeguard the region's primary potable water source.