Impacto das atividades antrópicas nas características químicas e microbiológicas das águas fluviais da cidade de São Miguel do Oeste - SC

Abstract

The urban space of the City of São Miguel do Oeste - SC is inserted in three hydrographic microbasins: dos Perdidos River, Guamirim River and Famoso River and, considering that human activities can impact the quality of water resources, this work aimed to study the influence of different human activities on the chemical and microbiological characteristics of water in the microbasins in question. Water samples were collected at different points of each river (head, middle and downstream) from September 2019 to August 2020 and taken to the laboratory for chemical and microbiological analysis. The data obtained were subjected to a principal component analysis, as well as classified according to the level of anthropic impact. The analysis of population concentration was performed using data from the Instituto Brasileiro de Geografia e Estatística demographic census and estimated the population of each microbasin through geoprocessing, crossing the information from the census sectors with the regions of the hydrographic microbasins. The soil occupation analysis was carried out through an in loco survey, visually identifying the buildings as to their occupation (residential, commercial, mixed and industrial) and subsequently georeferencing each building. In absolute values, in the three hydrographic microbasins analyzed, the predominant occupation was residential, followed by commercial and industrial. However, among the microbasins, the basin with the highest percentage of residential buildings was the dos Perdidos River; the Guamirim River basin had the highest percentage of commercial buildings and the Famoso River basin had the highest percentage of industrial buildings. As for the elements sodium, potassium, manganese, coliforms and hardness, water contamination varied among the analyzed microbasins. The basin that has the greatest anthropogenic impact was the Guamirim River microbasin, which may be related to the largest number of buildings and population residing in this territory. The other microbasins of the dos Perdidos River and the Famoso River, on the other hand, have a low anthropogenic impact and have a different reality from that reported in the Guamirim River microbasin. As urban expansion occurred over the decades, these areas were occupied by buildings and these by activities and/or inhabitants, which results in a greater population concentration in older areas, suffering from anthropogenic reflexes caused by pollutants found in the samples analyzed.