Water quality assessment of the Demetrio stream: an affluent of the Gravataí River in the South of Brazil.

L P Martins,A Beneduzi,L K Vargas,F R Silva,J Sampaio,R S Godoi

doi:10.1590/1519-6984.234692

Abstract

The Gravataí River basin, one of the main water sources of the metropolitan region of Porto Alegre, is among the ten most polluted rivers in Brazil. Water quality is monitored only through physico-chemical and microbiological parameters in Brazil, and in this context, considering the importance of the use of biomarkers in complementing the analysis of water, the present study aimed to evaluate the environmental quality of the main affluent of the Gravataí River, Demetrio stream, through physico-chemical, microbiological, and cytogenotoxic criteria, at the stream source (P1), whereas samples P2 and P3 were obtained from the upstream near the area with the highest urban density and the downstream near the meeting point with the Gravataí River, respectively. The results for copper concentration and color classified the Demetrio stream as Class 4 in general, that is, the water is suitable only for navigation and to landscape harmony. The main genotoxic alterations (micronuclei and nuclear buds) were observed in P2, in which were obtained the highest levels of copper, in addition to iron and manganese. Anthropic interventions were observed in P1 and P2; however, due to its low metal concentration, P3, near the Gravataí River, manifested an improvement in environmental quality.

Highlights

In recent years, human activities have posed serious threats to water resources (Kaliberda et al, 2008)
The industrial cluster has grown considerably over the past years as has the urban population as well and this generated an increase of pollutants dumped in the river, as a result of farming irrigation, water supply for animals, industrial and domestic sewage, solid residue, urban draining, rural diffusing sources, and atmospheric pollutants precipitation (Salomoni et al, 2011). In this context, considering the interest to assess the impact of pollutants dispersed in water, as well as the importance of the use of biomarkers to complement the water physicochemical analysis, this study aims to evaluate the environmental quality of the Demetrio stream water, main affluent of Gravataí River, through physical-chemical, microbiological and cytogenotoxic criteria
For most of the physicochemical parameters analyzed (Table 1), such as cadmium, lead, chloride, cobalt, total chromium, fluoride, mercury, nickel, nitrate, sulfate, zinc, turbidity, and pH, the water samples were classified within Class 1, according to the criteria established by CONAMA Resolution no 357 (Brasil, 2005), i.e., water destined to be supplied for human consumption post simple treatment, for protection of aquatic communities, and irrigation of raw vegetable crops

Summary

Introduction

Human activities have posed serious threats to water resources (Kaliberda et al, 2008). The quality of water for domestic supply is affected by pollution caused by different sources, such as domestic, industrial, urban, and agricultural effluents (Merten and Minella, 2002). The release of sanitary sewage into water bodies severely affects fauna, flora, and humans (Carvalho and Orsine, 2011). According to the National Sanitation Information System - SNIS (Brasil, 2015), the treatment rate increased by 11% between 2005 and 2015, only 42.7% of all Brazilian sanitary sewage is treated, and in some regions the rate is still less than 10%. In Brazil, polluted rivers water when monitored, its quality can be determined according to the standards established in the Resolution of the National Environmental

Objectives

Methods

Results

Discussion

Conclusion