Monitoramento da Qualidade da Água e Avaliação Ambiental do Rio Lajeado Lambedor, Erval Seco-RS

Abstract

Population growth results in large demands for water, but on the other hand this action also impacts its quality, therefore, it is essential to have knowledge about the characteristics of water to be able to detect possible contaminants. The objective of this work was to monitor the water quality of the Lajeado Lambedor River, located in the municipality of Erval Seco – RS (Brazil), through the evaluation of environmental variables. Physical, chemical and microbiological analyzes of the water were carried out, including pH, temperature, nitrite, total iron, total phosphorus, turbidity, electrical conductivity, true color, total nitrogen Kjedhal, total ammonia, nitrite and nitrate, dissolved oxygen, biochemical demand for oxygen, total solids, total coliforms and Escherichia coli. Five points were determined (P1 – source of the main river, P2 – source of the secondary river, P3 – section of the main river, P4 – section of the secondary river and P5 – final section), during a period of seven months. Afterwards, the results were compared and classified into water quality classes according to current legislation, this being the National Environmental Council Resolution n° 357 of 2005, except total Kjedhal nitrogen and electrical conductivity. Furthermore, a macroscopic environmental assessment of each point and the Water Quality Index were carried out. Regarding the classification according to legislation, points 1, 2, 3 and 4 in most months were classified as class 3, however point 5, in most months, was classified as class 4. Regarding the macroscopic environmental assessment the springs were classified as class C (Reasonable preservation level) and the other points were classified as class D (Poor preservation level). And for the Water Quality Index at the points, in general, it was classified as Good quality. The results obtained show that human activity directly influences the water quality of the Lajeado Lambedor River, suggesting that awareness and environmental education campaigns be carried out periodically, improvements in the vegetation cover around the rivers’ path and in the sewage system, and monitoring of the Lajeado Lambedor River and its tributaries should also be carried out more frequently.