Quantification of microplastics on anthropized and little anthropized beaches in Rio Grande do Sul coast, Brazil

Abstract

This study analyzed the presence of microplastics in the sediment of the three sandy beaches, in the North Coast of Rio Grande do Sul – southern Brazil, with different levels of anthropization. The beaches of Torres and Capão da Canoa are more urbanized than Praia das Cabras (Cidreira). The sampling was carried out along the four seasons of the year. In each locality, six square plots (0,5 x 0,5 m) were sampled, including three points at high tide mark and three points at the base of the dunes. The presence of microplastic was recorded in all samples. In total, 1.727 microplastics were collected (886 fragment units and 841 pellet units). Praia das Cabras showed a higher concentration of microplastic (1.083 units), than the urbanized beaches: Capão da Canoa (482 units) and Torres (162 units). In addition, a large amount of pellets was found in Praia das Cabras, whereas the other two beaches showed a greater accumulation of fragments. The highest accumulation of microplastic was found during spring (687 units), followed by winter (462 units), summer (410 units) and autumn (168 units). The presence of microplastics in sandy beaches seems not be related only to urbanization, but also to the continent-ocean interaction.

Keywords: sediment, beach, urbanization, microplastics