Influence of precipitation and currents on the inter and intra-annual fluctuation in the distribution of microplastics in the coastal environment of Kochi, Eastern Arabian Sea, southwest coast of India

Abstract

The inter- and intra-annual variations in the distribution of microplastics in surface waters and sediments of the Kochi waters were evaluated for 2019 and 2021 concurrent to the variable precipitation patterns. In both surface water and sediments, microplastic concentration was evidently high in 2021 than in 2019 reflecting the growing severity of plastic pollution in the coastal environment of Kochi. Spatial analysis revealed consistently higher microplastic concentration in both surface water and sediment at the inlet station irrespective of the sampling years. Intra-annually, the distribution of microplastics showed a positive relation with rainfall, indicating the determining role of precipitation in microplastic transport and distribution in the coastal environments. The study also revealed the influence of coastal currents in the spatial distribution of microplastics between the sampling locations positioned from coast to offshore. White and blue coloured fragments of polyethylene microplastics dominated the study region irrespective of the sampling periods.