Ocorrência e distribuição de microplásticos no Arquipélago de Abrolhos

Abstract

Plastic pollution is a major threat to oceanic, coastal and marine biota environments and has been documented for the last 40 years. The study of pelagic microplastics in islands of the Atlantic Ocean is recurrent, where the islands retain plastics of the adjacent sea by different metaoceanographics mechanisms, being one of the main factors for the decline of native species and degradation of the natural beauty. The objectives of this work were to determine the abundance, spatial distribution, composition and classification of microplastics in the Abrolhos Archipelago. In addition to improving the technique of quantification and measurement of particles through the process of visual identification and digestion of organic particles by nitric acid (HNO₃), and compare the samples obtained in different mesh apertures (64 μm and 200 μm). The Abrolhos reef complex covers the largest area of coral reefs in Brazil and the entire South Atlantic Ocean. The study region concentrated on points located about 10 - 70 km offshore. To identify the particles, techniques of visual counting and digestion by nitric acid were used. The densities underwent non-parametric statistical tests such as Wilcoxon / Mann -Whitney and Kruskal Wallis) to compare the central trends of the samples. Microplastics were classified according to their type: filaments, soft plastics, hard plastics and styrofoam. The 64 μm mesh was more effective in the capture of microplastics (4.19 mp / m-3) and 1.87 mp / m-3 in the 200 μm mesh. The two networks presented a similar general collection composition, since both had higher densities of filaments (64 μm 2.49 mp / m-3 and 2.15 mp / m-3 in the 200 μm mesh). The region farthest from the continent has a higher density of microplastics, as well as in the region closest to the coast. The use of the smaller mesh increases the collection capacity of plastic items, especially for filaments. Further research is needed to understand the distribution of microplastics and seek a mitigation of the various environmental problems caused by them.