Analysis of the occurrence of microplastics in beach sand on the Brazilian coast

Highlights: • We present an study on microplastics on beaches in the southeast and northeast of Brazil. • The extraction methodology was optimized. • Most of the microplastics found were white and of secondary origin. • The high amount of microplastic on a beach may be related to the mouth of one of the largest Brazilian rivers. • The amount of microplastic found can be related to the mouth of rivers. The occurrence of microplastics in coastal areas is a growing concern due to the increase in plastic waste pollution in recent decades. This study had as objective to evaluate the occurrence of microplastics in Brazilian beach sand, using a simple and fast methodology. In addition, possible microplastics were classified according to color, shape and chemical composition. The study was conducted on six beaches on the Brazilian coast: Pecado Beach (RJ), Castanheiras Beach (ES), Regência Beach (ES), Imbassaí Beach (BA), Viral Beach (SE) and Ponta dos Mangues Beach (SE). The methodology was adapted from international protocols, with section demarcation (100 m), where samples were collected from the superficial layer of the beach sand in ten quadrants (50 cm × 50 cm). The laboratory extraction procedure consisted of the density separation technique in two stages: the first used sodium chloride solution and the second used zinc chloride solution. For the visual inspection and screening procedures, a stereoscopic microscope was used. A total of 166 items of microplastics were collected on the six beaches on the Brazilian coast under study. The largest quantity of possible microplastics was recorded on the beaches of Viral (SE) and Ponta dos Mangues (SE) with 30.4 items/m² and 17.4 items/m², respectively. Regarding colour, white items were predominant (49.3%), and among particle types, fragments represented 85.1%. In addition, some microplastic particles were sent for FT-IR analysis, one of which was identified as being polyethylene. This study contributes to the knowledge of the presence of microplastics in different locations, and to supporting decision makers regarding coastal management.