Microplásticos na plataforma continental do Ceará: desembocaduras dos rios Cocó e Ceará

Abstract

Plastics are light synthetic organic polymers, resistant, durable, and inexpensive, which make them suitable for manufacturing a variety of products. Since the beginning of the production of plastic products in 1950, waste accumulates in various environments and although they have contributed to the quality of human life, they have become a threat to life when disposed of unduly in the environment. These residues can be separated into: macroplastics and microplastics, and can reach the sea through two main sources: by the accidental dumping and loss of ships and by the drainage of rivers and drainage systems. When they enter the marine environment, they are a threat to the biota, since they can be ingested. It is estimated that surface plastic concentrations in the open ocean range from seven thousand to thirty-five thousand tons. There are no studies of the amount of microplastics in the Ceara continental shelf (PCCE) however, it is known that the Coco and Ceara rivers, which cut through the Fortaleza region, indirectly receive domestic and industrial sewage and drainage water which drain into the ocean and can carry plastic particles. So, the objective was to make a qualitative-quantitative survey of microplastics (MPs) at the mouths of the estuaries of the Coco and Ceara rivers (continental shelf of Ceara). The research was carried out in two areas of the coast of Fortaleza, at the mouths of Coco River and Ceara River, on April 9th and 10th . Sea surface water was with trawls of plankton. The samples were taken to the lab, filtered, separated into fractions of microplastics> 0.3 mm and <0.3 mm, and submitted to wet oxidation for the digestion of organic matter. Then, the MPs were quantified by microscopy and characterized. Microplastics were found at practically all points collected in the Coco River and Ceara River. In all, 187 MPs> 0.3 mm and 39 MPs <0.3 mm were measured at the mouth of the Coco River, resulting in a total mass of MPs of 2.01 g. Near the Ceara estuary, 167 MPs> 0.3 mm and 49 MPs <0.3 mm were quantified, and the total mass of MPs recorded was approximately 4.07 g. The microplastics presented color variation and were classified into two formats: filament and fragment. These results are probably due to the influence of the mouths of the Coco and Ceara rivers which, being the main rivers that drain the city of Fortaleza, suffer from the effects of disorderly urbanization, such as the inappropriate disposal of residues on the banks of the rivers, and lead waste directly into the sea. It is not possible to say whether the amount of microplastics found in this study is high or not, since there is no current legislation to be used as a parameter. However, the abundance of microplastics recorded in this study is lower than in regions with higher population density.