Microplastics distribution and characterization in epipsammic sediments of tropical Atlantic Ocean, Nigeria

Abstract Recent reports indicate that microplastics (MPs) show both temporal and spatial variations therefore, regional data collection and environmental dynamics are vital aspects of understanding the underlying sources and factors that influence the abundance and dispersion of the plastic particles. This paper presents a baseline report on the abundance of microplastics across three tidal waterlines (high, drift and current) of the tropical Atlantic ecosystem. Microplastics (1 – 5 mm) occurrence and distribution in epipsammic sediments of five beaches in Lagos, Nigeria (Gulf of Guinea) were assessed. The microplastics were extracted by density flotation using saturated solution of NaCl and the identification of polymer types was done by attenuated total reflectance Fourier transform infra-red spectroscopy, ATR-FTIR. Results showed significant variations in the population of MPs in the three tidal waterlines with the high and drift waterlines accounting for 58.83% and 41.16% of the total MPs, respectively while no MPs were detected in the current waterline sediment. Polyethylene, polystyrene and polypropylene were the most abundant polymers recorded. Fragments were predominantly detected and pre-production pellets formed only 5.27% of total microplastics. Polymer risk index calculations showed low to medium risk of the microplastics found and local hydrodynamic conditions such as Ocean surges and current intensity were observed to influence the distribution and dispersion of microplastics. Continuous monitoring of MPs abundance is necessary to minimize the polymers’ risk to the ecosystem.