Quantification of microplastics in urban streams: a case study in the Manga stream in Várzea Grande/ Mato Grosso State – Brazil

Abstract

Population density, combined with the lack of basic sanitation services, contributes significantly to the increase in plastic waste in the environment and, consequently, the production of microplastics. Due to the potential effects on ecosystems, these microparticles have been the target of investigations, however, knowing the sources and abundance of these particles is a crucial point for understanding environmental risks. This research aims to investigate the abundance of microplastics in the water of the Manga stream, in Várzea Grande - MT.  To this end, 3 liters of water were collected at 3 sampling points during the dry period.  The samples were sieved through sieves, with particle sizes of 150 µm and 65 µm, and the retained material, on the smaller particle size sieve, was added to a hydrogen peroxide solution (25%) for 7 days and then subjected to density separation. Microplastics were quantified in terms of morphotype and color. The results revealed that on average, 41.66 fibers.L^-1, 12 filaments.L^-1 and 4.33 films.L^-1 were found in P1, while in P2, there were 56 fibers.L^-1, 5 filaments. L^-1 and 1 film.L^-1 and in P3, 38.33 fibers.L^-1, 17 filaments.L^-1, 4 fragments.L^-1 and 0.66 films.L^-1. Colorless fibers were found in greater quantities in all samples, totaling 31 microfibers.L^-1 at point P1, 39.66 microfibers.L^-1 at P2 and 28.33 microfibers.L^-1 at P3. The abundance of microplastics reveals the need to develop more effective awareness strategies regarding the disposal and management of solid waste, as well as an improvement in the treatment of domestic and industrial effluents.