Pressão urbana em água superficial do Ribeirão Lindóia: qualidade, toxicidade e contaminação por microplásticos

Abstract

Although it brings positive socioeconomic transformations, urbanization links with substantial environmental impact. In recent years, the effects on the environment matrices have intensified due to large-scale production and consumption patterns, leading to increased improper solid waste disposal and the presence of hazardous substances in urban products known as emerging pollutants, causing environmental problems such as water pollution. Therefore, ecosystem monitoring becomes necessary. In this context, this study aimed to analyze the influence of anthropogenic activities on the surface water quality of the Lindóia stream micro-watershed in the city of Londrina, as well as to investigate the first evidence of emerging contamination by microplastics. Five sampling points were determined along the Lindóia stream, dividing them into sampling sections; thematic maps of "land use" were created, and physicochemical and microbiological analyses were conducted, with toxicity tests using Allium cepa seeds and application of different methodologies for microplastic identification in water. Analysis of the thematic maps revealed that the Lindóia stream micro-watershed is predominantly urban. During field visits, several points of improper solid waste disposal were found in most sampling points, either in areas near the Lindóia stream or its banks, becoming one of the most recurrent environmental problems in the study area. Anthropogenic pollution was observed through the correlation of electrical conductivity, pH, total coliforms, and Escherichia coli (E. coli) parameters, especially after rainfall events, indicating that the water body incorporates the consequences of its predominantly urban surroundings. Also, the fecal contamination indicator, E. coli, exceeded the values established by legislation for the classification of the Lindóia stream, indicating a potential source of pollution. As for the toxicological analyses, the surface water of the Lindóia stream showed low to moderate toxicity. Finally, microplastics were found in all sampling points, once again highlighting the anthropogenic pressure the stream suffers from. Among the microplastic particles found, reddish fragments ranging from 20 to 50 μm and blue and black fibers ranging from 50 to 200 μm were notable, with the latter being the only ones visible to the naked eye.