Abundance and composition of microplastics in Tampico beach sediments, Tamaulipas State, southern Gulf of Mexico

Abstract

The abundance and characteristics of microplastics (MPs) in coastal sediments from the Tampico beach, Gulf of Mexico was investigated. The MPs were extracted by a density separation method with saturated solutions of NaCl and ZnCl₂, the sediment-solution relationship was 1:3. MPs were classified according to its shape, color, and size under a stereoscopic microscope. Identification of MPs surface was carried out by a Scanning Electron Microscope (SEM). The polymer types were detected by a Fourier-transformed infrared (FTIR) Spectroscopy. Number of MPs in 20 g of sediments varies from 256 to 283 particles. The average abundance of MPs per kg was inferred as ∼13,392 microplastic particles. Fiber was the only MP particle identified in the Tampico beach, its size varied from 1.76 mm to 3.92 mm. Fibers identified were mostly transparent, blue, white, black, multicolor, yellow, pink, and red. Six different polymers were identified, i.e., polyester (PES), polyethylacrylate (PEA), cellophane, polyacrylonitrile (PAN), polystyrene acrylonitrile (SAN), and polyvinyl acetate ethylene (PVAE). PES is the most prevalent polymer in all samples.

Keywords: Degradation; Fiber; Infrared Spectroscopy; Microplastics; Polyester; SEM.