ABSTRACT

 The study to quantify and identify the microplastics in coastal areas of Lagos State Nigeria was carried out between the period of April 2018 and February 2019 covering the wet and dry seasons. The research involves sampling of ten (10) beaches and six (6) lagoon locations and two (2) species of fish - Flathead grey mullet (Liza grandisquamis) and Red snapper (Lutjanus campechanus), for the presence of microplastics. Microplastics were isolated using standard protocols and the abundance shape, colour and identity of isolated microplastic particles were determined using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Energy Dispersive X-Ray Spectroscopy- Scanning electron microscopy (SEM - EDX). A total of 196 particles were present in water samples across the 10 beach locations during the wet and dry seasons with high abundance observed in site A, site B, site C areas around Oniru, Elegusi, Eleko and Alpha beaches (Site A >Site C> Site B). A total of 685 microplastic particles were also found in the beach sediment studied during the wet and dry seasons. In the lagoon area, a total of 405 microplastic particles were found in Sediment samples studied during the two seasons, respectively. The correlation analysis of the relationship between the physicochemical properties showed no correlation between the Sheet, Beads, Foam, Fragment, Pellet in both size categories of <5mm and <2.5mm and the physiochemical properties while there were correlation (p = 0.05) between of Sheet and Salinity and Conductivity. There was no correlation between 2.5mm of Fiber, Sheet, Beads, Foam, Fragment, Pellet, and the physiochemical properties of lagoon water. Microplastics were detected in both species of the fish. Grey mullet showed greater abundance in both site-1 and site-2, but there was no significant difference in the abundance in same species from different sites when statistical analysis was carried out using the SPSS packages. Microplastics in water, sediments and fishes were in various shapes including fiber, sheets, beads, foams, fragments, and pellets. Scanning Electron Microscope (SEM) coupled with Energy dispersive X-ray unit (EDX) ZIESS-EDAX was used to investigate the surface morphology and chemical composition of the microplastic particles. The different microplastics scanned showed different morphological features on their surfaces. The images from the scan showed different surface roughness in the microplastics, indicating that the microplastics have complex surface characteristics which can be characterized as rough, porous, cracked, colored and morphological diversity. The distribution of the major elements associated with the microplastic particles above showed the presence of C, N, O, Mg, Al, Si, P, S, Cl, and K with C, N, O, and Cl being most dominant judging by the atomic percentages. The surfaces of pellets and fragments showed some contour and protrusions varying in their sizes. Mechanical weathering textures, including linear fractures, mechanical pits, and grooves, were predominant in microplastic samples from Oniru, Elegushi, the area near Eko Tourist and the Onikan Bridge area than in other beaches. This research showed the presence of microplastic particles in the water, sediments and fish in the Lagos coastal area and has confirmed that there are seasonal variations in the microplastic abundance. It is recommended that Government should establish monitoring programme for microplastics, ensure proper funding of microplastic research and establish a framework for management and control of plastic waste across the country.