Microplastic contamination in surface waters in Guanabara Bay, Rio de Janeiro, Brazil

Microplastics (MPs) are contaminants of environmental concern that represent a threat to marine systems. Here we report data on the abundance and characteristics of MPs collected from surface waters of the urban Guanabara Bay. Samples were collected, by horizontal trawling of a plankton net on two occasions (summer of 2016). The MPs were obtained from samples by sieving and particles were manually sorted with microscope. Characterization of MPs was accomplished by gravimetry and digital image processing (for quantification and morphology categorization), and chemical composition identified by infrared spectroscopy and elemental analyses. Total MPs ranged from 1.40 to 21.3 particles/m³, which places Guanabara Bay amongst the most contaminated coastal systems worldwide by microplastics. Polyethylene and polypropylene polymers ≤1 mm were the most abundant particles. Therefore, the occurrence of MPs in Guanabara Bay is relevant to understand ecological hazards of exposition to marine biota and merits further investigation.