Maria do Carmo Cauduro Gastaldini

Avaliação da qualidade da água em bacias hidrográficas com diferentes impactos antrópicos

The unbalanced use of soil without a proper conservationist treatment as well as the improper anthropogenic actions may cause alterations in the local water quality and can induce the pollution of water resources. This study aimed to evaluate the water quality in watersheds with distinct use and occupation of the soil of the Vacacai-Mirim River in the municipality of Santa Maria, Rio Grande do Sul, Brazil. Water quality parameters were statistically analyzed in periods of dry weather and assessed using the Pearson correlation coefficient. Alto da Colina watershed, with the smallest area (2 km2), presented the highest percentage of urbanization and the largest population; however, it showed the worst results regarding environmental degradation when compared to the other watersheds studied. This result is due to the influence of the domestic effluent as a potential source of contamination of the water system and due to the high contribution of organic matter, pathogenic agents, and nutrients. The different uses of soil have caused alterations in the relations between the water quality parameters analyzed. In watersheds where agricultural areas are predominant, the influence of turbidity and suspended solids was significant due to the occurrence of erosive processes.

An assessment of quality of stormwater in a subtropical urban watershed

The lack of a proper collection network combined with insufficient or ineffective treatment of the collected wastewater means that household wastewater greatly affects the quality of water resources in Brazil. This study aims to assess the presence of organic pollutants, nutrients and heavy metals in water, suspended river sediments and bottom sediments and determine the mean concentrations of pollutants in events in an urban watershed. The watershed investigated is located in Santa Maria, a city in the state of Rio Grande do Sul, Southern Brazil. Water quality parameters were analyzed using event mean concentrations (EMC), pollutant bioavailability in bottom sediments and Pearson’s correlation coefficient. Soil use and occupation were shown to dramatically affect the water quality of rainwater runoff. The bioavailable fractions of heavy metals in bottom and suspended sediments did not exceed the threshold set by the applicable Brazilian National Council for the Environment Resolution (CONAMA 454/2012) nor the sediment guidelines of the Canadian Institute for Environmental Law and Policy. Stormwater samples showed high concentrations of TS, SS, SD, BOD, COD, Cu, Ni, Pb and NO2−. EMC tended to display higher values as rainfall and precipitation increased. The accumulation of pollutants on streets and urban drainage is also influenced by the antecedent dry period. The body of water receives a massive intake of pollutants during the flood wave.

Nonpoint pollution load in river catchments with different anthropic impacts: a case study in Southern Brazil

Diffuse or nonpoint source (NPS) pollution results in different pollutant concentrations, which depend on river catchments, land use and precipitation events and may vary along a single event. This study aimed to assess NPS pollution loads of organic matter, nutrients, bacteria and heavy metals in four river catchments associated with different types of land use in Southern Brazil. Cluster analysis was used to identify similarities between basins and main component analysis (PCA) to identify the main variables that characterize diffuse pollution in each basin. The use and occupation of the soil were determinant in the formation of the clusters. The basins with rural characteristics formed one group, whereas the basin with urban characteristic generated another group. PCA suggests that changes in the water quality of the catchments in this study can be explained by organic pollutants and farming activities. The Rancho do Amaral catchment, with 55.8% of native forest, displayed the lowest NPS pollution load for all tested parameters. The Alto da Colina catchment, with the largest urban area and largest agricultural land use (50%), showed the highest NPS for all variables in the study, even though it has the smallest area. The differences in pollutant loads can be attributed to the intense degradation processes associated with anthropic activities, such as urbanization, agricultural activity and the discharge of effluents, which are different for each catchment.

Variação da qualidade da água de chuva com a precipitação: aplicação à cidade de Santa Maria - RS

This study aimed to evaluate the quality of rainwater in the city of Santa Maria - RS, to assess the variation of some parameters during precipitation, and to identify the most appropriate uses for rainwater depending on the current standards for the use of rainwater and reuse water. Rainwater samples were collected directly from the atmosphere and a roof in order to analyze the changes in quality after passing the catchment surface. Each sampler was divided into five compartments to collect and store separately the first five millimeters of rain. The quality characteristics of rainwater were assessed using the following parameters: pH, conductivity, turbidity, BOD5, total solids, suspended solids, dissolved solids, and Escherichia coli. In some events iron, manganese, phosphate, ammonia and nitrate were also analyzed. It was observed that the quality of rainwater changed after its passage through the catchment. In raw state, rainwater can be used for non-potable purposes, it being recommended to discard at least the initial 2 mm. If treated, rainwater acquires a quality compatible with other uses, such as flushing toilets and washing vehicles. The behavior of some parameters was sensitive to changes in the precipitation characteristics, and there was a variation in the values related to the increase or decrease in the intensity of rainfall.

Resíduos sólidos em um sistema de drenagem urbana no município de Santa Maria - RS

With population growth, and the resulting increase in urbanization, the disposal of solid waste in the urban drainage system has increased in recent years, especially in the outskirts of the cities. This study aimed to qualify and quantify the solid waste in Cancela-Tamandais stream, located in an urban area, in the municipality of Santa Maria (RS). Were collected in total 1.153.2 kg of solid waste with a rainfall total for the period of 518.94 mm, 93.9% of these being composed of organic matter with the majority of vegetation debrid. Cancela-Tamandais watershed presented a load of solid waste equal to 17.27 or 0.424 kg.inhab-1.year-1. The prediction curve of drained solid waste due to the rainfall correlated 76.4%, important parameter for decision making of municipal managers in relation to solid waste generated. Thus, devise strategies for monitoring these residues represents an important step in finding solutions aimed at better management of urban watersheds.

Classification Of Water Resources In River Basins With Lack Of Data: A Case Study In Southern Brazil

This paper aims at the analysis and development of technical and methodological basis for classification of water resources bodies in river basins with lack of data. It was based on Brazilian’s water quality standard. The Vacacai Mirim River Basin, with 1120 Km2 of drainage area, located between the latitudes -29° 36’ 55” and -29° 39’ 50” and longitudes -53° 46’ 30” and -53° 49’ 29, in southern Brazil was used as a case study. A water usage classifier proposal was presented to the government office for management of water resource of the state of Rio Grande do Sul, which is based on the characterization of the physical environment and the water quality, as well as an estimation of availability and consumption of water. The estimated total water consumption in the basin in 2005 was 141,542,873 m3, being 7.53% for public supply and 92.47% for the irrigation of rice crops. Characterization of the water quality was carried out using QUAL2E model, which applied samples collected on field expeditions at ten spots of the river. Estimation of the natural flow was based on a new simplified methodology based on the SMAP model and on a genetic algorithm to optimization. Input data consisted of the observed flow at the basin’s outlet, and the estimated water consumption for irrigation as well as for public supply. Results have shown that the developed methodology is well suited for basins of rivers subjected to intensive water usage and with limited amount of data.