Ocorrência de microplásticos na foz do rio Cocó (Fortaleza/CE) no período chuvoso

Abstract

Microplastics are defined as synthetic polymers with a range between of 1 µm to 5 mm, which are created from the abrasion of larger plastics or are already produced in this size range. As they are small and widespread in the environment, they currently pose a major problem for wildlife and humans. The mouths of rivers are one of the main entry points of microplastic into the ocean, as the river serves as a transport route for this pollutant from the continent. The aim of this work is to determine the abundance of microplastics in the surface waters at the mouth of the Cocó River in Fortaleza, Ceará, during the rainy season and characterize them in terms of shape, size and colors. Sampling was collected in April 2022 at a single point at the mouth of the Cocó River through three consecutive drags using a plankton net with a mesh size of 120 µm and a flow meter attached to it. The sample was analyzed in the laboratory, where it was sieved, freed from organic material by a digestion solution, separated by density differences and filtered. The filtered sample was analyzed under a stereomicroscope to count the MPs and classify them by shape, size and colors. The average abundance was 8.98 ± 3.26 items/m³. The predominant forms were fibers (49%), followed by rubbers (20%), fragments (17%) and films (13%). The predominant size ranges were 0.3 mm to 0.5 mm (25%) and 0.5 mm to 1,0 mm (25%). The predominant colors were black (29%), blue (22%) and transparent (21%). we can conclude that the potential sources of microplastics for the Cocó river are the discharge of sewage, the incorrect disposal of solid waste and the wear of tires on avenues and roads, and that the Cocó river is a large contributor of microplastics to the ocean Atlantic.