Pardo River Research Articles

CARACTERIZAÇÃO MORFOMÉTRICA E COMPORTAMENTO HIDROLÓGICO DA BACIA HIDROGRÁFICA DO RIO PARDO

A morfometria das bacias hidrográficas representa quantitativamente fatores determinantes no comportamento do escoamento superficial, vazões e seus tempos de concentração. O conhecimento dos fatores que influenciam a hidrologia da região fundamenta o planejamento e a gestão dos recursos hídricos e subsidia as ações mitigadoras de diversos problemas frequentemente observados como a escassez hídrica, chuvas concentradas e inundações. Este trabalho visa interpretar a morfometria da bacia do Rio Pardo, gerando informações para o auxílio e apoio das atividades de manejo, por intermédio da caracterização morfométrica e associação dos parâmetros ao comportamento hidrológico na região, utilizando dados da estação fluviométrica e sistema de informações geográficas (SIG). Os parâmetros morfométricos analisados neste estudo contemplam aqueles referentes à caracterização da conformação da bacia hidrográfica, da topografia e da rede de drenagem. As vazões do rio Pardo analisadas referem-se ao período de 1954 a 2011, por meio do estudo das vazões máximas, média de longa duração, específica e de permanência (Q95, Q90, Q7,10). A bacia de contribuição do Rio Pardo possui área de 433,65 km², fator de forma com valor 0,97, formato ovalado e montanhoso, com elevada amplitude altimétrica de 901 m, características que favorecem a ocorrência de inundações na bacia. Além disso, a proximidade da Serra do Caparaó e sua influência orográfica aumentam os riscos de períodos mais chuvosos e intensos, ocasionando vazões máximas elevadas, 108,06 m³s-1, e aumentando o risco de inundações.

Cardiovascular risk, lifestyle and anthropometric status of rural workers in Pardo River Valley, Rio Grande do Sul, Brazil.

The state of health of rural workers is influenced by the living conditions to which they are subjected, including social, economic, technological and organizational aspects. Given the scarcity of studies on this population of workers, establishing their profile is necessary. To analyze cardiovascular risk according to demographic factors and anthropometric status of rural workers under the Pardo River Valley Regional Development Council (COREDE-VRP). Cross-sectional analytical study with rural workers in five municipalities in the COREDE-VRP southern region. We administered a structured questionnaire for lifestyle socioeconomic information, physical activity and self-reported health. Anthropometric measurements, resting heart rate and electrocardiogram (ECG) were performed to analyze heart rate variability (HRV). Women exhibited higher cardiovascular risk, which in turn did not differ as a function of age, marital status, socioeconomic status or lifestyle. We found a relationship between cardiovascular risk and anthropometric measurements, but not with cardiovascular variables. Women exhibited higher cardiovascular risk, which was not associated with marital status, socioeconomic status, alcohol use, smoking, sleep disorders or physical activity. Therefore, we emphasize the relationship between cardiovascular risk and anthropometric variables, as well as the lack of association with heart rate and autonomic imbalance.

Caracterização da fauna cavernícola e da flora rupícola da cavidade do Morro Redondo, Iúna/ES

A equipe de pesquisadores da empresa Helium Corp Engenharia elaborou o inventário bioespeleológico da cavidade do Morro Redondo, localizada na sub-bacia do rio Pardo, no município de Iúna localizado na Serra do Caparaó, também foi analisada a sua relevância, segundo a Resolução CONAMA nº 347, de 10 de setembro de 2004 e a Instrução Normativa nº 2, de 30 de agosto de 2017. A área de estudos localiza-se no distrito de Nossa Senhora das Graças, na comunidade do Morro Redondo. De acordo com o Centro Nacional de Pesquisa e Conservação de Cavernas (CECAV), a cavidade do Morro Redondo é a única caverna registrada para o município de Iúna-ES no Cadastro Nacional de Informações Espeleológicas (CANIE) até a síntese deste estudo. A cavidade foi topografada e teve seu inventário bioespeleológico realizado, assim como a sua caracterização histórica e cultural, fatores que possibilitaram avaliar a sua relevância. Com a ampliação do número de ocorrências de cavernas para a Serra do Caparaó, será possível uma melhor caracterização do perfil das cavernas desenvolvidas na região de Iúna. Portanto, espera-se que a divulgação dessa pesquisa, possa contribuir como base para futuros estudos bioespeleológicos na região.

Conflitos do uso de solo em áreas de preservação permanente em Candelária (RS)

The urbanization process of Brazilian cities has generated several environmental problems, including occupations and irregular uses in Permanent Preservation Areas (PPA). Land use in marginal strips, coupled with vegetation removal, causes environmental degradation, causing instability of ecosystems. For this reason, the present study aims to identify and analyze land use and land occupation conflicts in PPA localized in the urban perimeter of the municipality of Candelária, Rio Grande do Sul, Brazil. The methodology uses geographic and statistical data from the Brazilian Institute of Geography and Statistics (IBGE) and spactial bases provided by the municipal government. Data systematization and maps elaboration were performed in Geographic Information System (GIS) platform. Candelária presents streams that cut the urban mesh and flow into the Pardo River, thus, there are PPAs of considerable size within the urban area. Research shows that there are improper uses in PPA, such as buildings, irregular settlements and agricultural crops. Finally, the results indicate there is significant area under protection in the city being impacted by human action, aggravating the reduction of native forest.

Methodology for minimum nitrogen compounds removal efficiencies estimation and wastewater treatment systems pre-selection: a watershed approach

ABSTRACT Nitrogen is a very important parameter for water pollution control since nitrification implies in aquatic environment oxygen consumption and some nitrogen forms are toxic. In the present study, an optimization model was developed and applied aiming at simultaneous organic matter and nitrogen compounds minimum removal efficiencies determination. A water quality model and the Genetic Algorithm Metaheuristic were associated in order to solve the optimization problem. The estimated minimum efficiencies conditioned the sewage treatment systems pre-selection. The study area was the Pardo River watershed (Espírito Santo State, Brazil). The results indicate that the treatment systems need to be more efficient in ammonia removal when the treated effluents disposed in watercourses that present high pH values because ammonia toxicity increases with pH. Considering the boundary conditions assumed in this study, the pre-selection process indicated activated sludge systems, submerged aerated biofilter with nitrification, or with biological nitrogen removal, for Ibatiba city. Simpler systems such as primary treatment with septic tanks, stabilization ponds, UASB reactors and biological filters were pre-selected for Santíssima Trindade and Nossa Senhora das Graças towns.

Sensibilidade do copépode Nitokra sp. à exposição ao agregado óleo-material particulado em suspensão (OSA)

In an oil spill in mangrove areas, there is a great possibility of oil aggregation with suspended particulate matter, which may determine the bottom sediment as the final destination of OSA (Oil-Suspended Particulate Matter Aggregates), posing a great risk to Benthic organisms. Ecotoxicity tests with these organisms have been widely used as one of the most accurate forms of biological monitoring of the anthropogenic impacts on this ecosystem. The present work evaluates the ecotoxicity of the exposure to OSA in mangrove sediments, collected along the Pardo river estuary, Canavieiras, Bahia, through pilot scale (microscale) trials. The procedure was performed using acute exposure toxicological tests to determine LC50 (lethal concentration 50%) using the benthic copepod Nitokra sp. For the purpose of comparison, two scenarios were performed, the first considers the aqueous phase of the OSA simulation protocol in microscale, and the second, the elutriate from sediment and oil homogenized in different fractions. It was verified that the formation of the OSA has a much less toxic potential (LC50 70.71) in relation to elutriate formed from the percentages of homogenized sediment with crude oil (LC50 5.59) confirming its potential as an effective form of cleaning for oil treatment in water.

Sensibilidade do copépode Nitokra sp. à exposição ao agregado óleo-material particulado em suspensão (OSA)

In an oil spill in mangrove areas, there is a great possibility of oil aggregation with suspended particulate matter, which may determine the bottom sediment as the final destination of OSA (Oil-Suspended Particulate Matter), posing a great risk to Benthic organisms. Ecotoxicity tests with these organisms have been widely used as one of the most accurate forms of biological monitoring of the anthropogenic impacts on this ecosystem. The present work evaluates the ecotoxicity of the exposure to OSA in mangrove sediments, collected along the Pardo river estuary, Canavieiras, Bahia, through pilot scale (microscale) trials. The procedure was performed using acute exposure toxicological tests to determine LC50 (lethal concentration 50%) using the benthic copepod Nitokra sp. For the purpose of comparison, two scenarios were performed, the first considers the aqueous phase of the OSA simulation protocol in microscale, and the second, the elutriate from sediment and oil homogenized in different fractions. It was verified that the formation of the OSA has a much less toxic potential (LC50 70.71) in relation to elutriate formed from the percentages of homogenized sediment with crude oil (LC50 5.59) confirming its potential as an effective form of cleaning for oil treatment in water.

Water Quality Assessment of the Pardo River Basin, Brazil: A Multivariate Approach Using Limnological Parameters, Metal Concentrations and Indicator Bacteria.

Located in the southeast of Brazil, the Pardo River Basin has a large population and an economy focused on agriculture, with a strong predominance of the sugarcane agro-industry. The purpose of the study was to assess the water quality of the Pardo River Basin under a multivariate approach using limnological parameters, metal concentrations, and indicator bacteria. Nine sampling campaigns were performed during both the dry and rainy seasons. Element concentrations were determined by inductively coupled plasma spectrometry (ICP-MS, Perkin Elmer Elan 6000). A battery of test to determine limnological parameters was performed (in situ). Total coliforms and Escherichia coli were detected and quantified using Defined Substrate Technology Colilert® and multiple tube dilutions. Principal component analysis and hierarchical cluster analysis were used as multivariate exploratory analysis. In general, the results suggest the influence of rain, possible sewage discharges into the watercourse, and the input of organic matter in some sampling points in both seasons, besides the absence of riparian vegetation in much of the Pardo River. The likely influence of industrial activities that do not have great prominence in the region was supported by temporal/spatial assessment of Cr and V. The water quality monitoring of Pardo River is an important tool for environmental management, and its continuity is indicated to obtain a consistent series of systematic data and thereby support concretely the actions of planning and controlling the use of water from the Pardo River and soil around them.

Health risks of environmental exposure to metals and herbicides in the Pardo River, Brazil.

Mixture of metals and herbicides in rivers may pose relevant risks for the health of surrounding communities. Humans may be exposed to river pollution through intake of contaminated water and fish, as well as irrigated agricultural products. The aim of this study was to assess the human health risks of environmental exposure to metals and herbicides through water and fish intake in the Pardo River. Metals (Al, As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V, and Zn) were analyzed in river water and in edible fish. Herbicides (ametryn, atrazine, diuron, hexazinone, simazine, and tebuthiuron) were analyzed in river water. Seasonal variances were also studied. Aluminum, Cd, Cu, Mn, Pb, and Zn levels in river water were higher than the USEPA benchmarks. Non-carcinogenic risks due to pollutants mixture exposure were above the limit, and carcinogenic risks of As exposure were >10-6 in the sampling points during the rainy season. Metal levels in fish were lower than the Brazilian legislation and do not pose a threat to public health. Herbicides were detected in four sampling points, with atrazine concentrations (range 0.16-0.32μg/L) below the Brazilian standard (2.0μg/L), but above the European Union standard (0.1μg/L). Considering the water supply needs of cities located in the Pardo River Basin and the persistence of metals and herbicides, the present study indicated that there was a seasonal influence on non-carcinogenic and carcinogenic risks to human health, especially in the rainy season. Studies for water treatment plants implantation should consider the risks of exposure to persistent substances, in order to protect the population.

How fast are soil-forming processes in Quaternary sediments of a tropical floodplain? A case study in southeast Brazil

Floodplains are depositional features of a channel valley associated with a specific climatic and hydrologic regime of a drainage basin. In tropical conditions, sediments can be quickly weathered by soil-forming processes and tend to obliterate pre-existing sedimentary structures. Therefore, the objective of many studies on floodplains is to identify and discuss such sedimentary features, mostly those related to the morphology of channel deposits. Additionally, a qualitative approach to identify aspects of pedological evolution in these environments has been attempted in few studies. The purpose of this study was to interpret the intensity and the time of alluvial sediment weathering by pedogenetic processes in tropical humid conditions. Soil profiles were analyzed in different environments of deposition in the Pardo River floodplain (southeast Brazil) by accounting for sedimentary facies and pedological features supported by multi proxy data provided from geochemistry, macro- and micromorphology, grain size, total carbon, total nitrogen, 13C isotopic analysis and 14C/OSL (optically stimulated luminescence) dating. Based on the results, we identified that pedogenetic features and soil horizon distributions were closely related to sediment architecture, grain size and position in the floodplain. In the Pardo floodplain, Fluvic Gleysols (Loamic and Clayic) with moderately to strongly developed structures were identified in overbank fine sediments. Fluvic Cambisols (Clayic) were found in abandoned paleomeanders, Fluvic Cambisols (Loamic) in sandy scrollbars, Gleyic Acrisols (Clayic, Cutanic, Differentic) in channel deposits, which presented a 130-cm-thick Bt horizon with illuvial clay coatings, and Histosols (Fluvic) with high contents of total carbon (11.9% and 26.8% in histic horizons) in small-scale avulsive systems. Deposits were dated to between 35,000 and 700years BP. 13C isotopic data revealed a trend toward enriched values in older samples (−14.21‰) in which C4 plants dominated and a relative impoverishment of the values in more recent samples (−26.9‰ to −27.9‰). This result was consistent with the tendency of the distribution of C3 plants to increase over that of C4 plants, favored by the warmer and wetter climate since the Upper Holocene. In this study, a Fluvic Gleysol profile of <1000years and a Fluvic Cambisol of <700years were identified. Nevertheless, our primary contribution is to highlight that soil evolution in this specific situation could be more efficient than expected. Moreover, to provide consistent analyses in future studies, tools from both sedimentology and pedology are essential.

Astyanax lineatus (Perugia, 1891) (Characiformes: Characidae): first record in the upper Paraná river basin, Mato Grosso do Sul, Brazil

Astyanax lineatus was previously known only from the Paraguay river basin and we report the first record from the Paraná river basin near the municipality of Sidrolândia, Mato Grosso do Sul state, Brazil. The species was found in Lajeado Stream, a tributary of the Anhanduí River, which belongs to the Pardo River sub-basin of the Paraná river basin.

Proposal of a methodology for pre-selection of sewage treatment systems within watersheds

ABSTRACT The selection of sewage treatment plants within watersheds is a complex process when there are multiple outflows presenting different loads and watercourses presenting different assimilation capabilities. In this context, the present study aims to establish a methodology for pre-selection of wastewater treatment alternatives within watersheds. The methodology involves the combined use of water quality model, optimization technique and a set of technical and economic criteria associated with different wastewater treatment systems. To evaluate the proposed methodology there were considered different effluent disposal scenarios in the Pardo river watershed. Pardo is a major tributary of the Itapemirim river, watercourse located in the southern portion of Espírito Santo State, Brazil. The results indicated that the optimization model, that aimed to minimize wastewater treatment efficiencies within the watershed, considering watercourses self-purification capacities, selected treatment systems ranging from the combination of UASB and polishing lagoons systems to slow infiltration, treatment alternatives that presented the lowest net cost estimates. The incorporation of equity perspective between treatment systems increased the total present net cost associated with wastewater treatment within the watershed.

Performance evaluation of optimization models in the determination of wastewater treatment efficiencies inside watersheds

ABSTRACT Determination of sewage treatment plants pollutant removal efficiencies, considering the protection of water resources, is very difficult because it involves complex analysis that must take into account multiple discharges into watercourses presenting different self depuration capacities. The research aimed to evaluate different optimization models for determination of minimum sewage treatment efficiencies for plants located in a watershed. The analyzed optimization models involves minimization of the sum of treatment efficiencies and minimization of inequity between sewage treatment efforts. Water quality mathematical model and Genetic Algorithm were combined in a MatLab software computing environment. The Pardo river watershed is the study area. Pardo river is a tributary of the Itapemirim river, important watercourse located in the southern part of Espirito Santo State, in Brazil. The results indicate that the optimization models that incorporate measurement of equity as a problem restriction did not generate consistent answers, probably because of the wide range of sewage loads values considered in the Pardo river watershed. The models that incorporate equity measures in the objective function showed satisfactory performance and resulted in very close values for minimum sewage treatment efficiencies.

Meiotic behavior and H3K4m distribution in B chromosomes of Characidium gomesi (Characiformes, Crenuchidae).

Characidium gomesi Travasso, 1956 specimens from the Pardo River have up to four heterochromatic supernumerary chromosomes, derived from the sex chromosomes. To access the meiotic behavior and distribution of an active chromatin marker, males and females of Characidium gomesi with two or three B chromosomes were analyzed. Mitotic chromosomes were characterized using C-banding and FISH with B chromosome probes. Meiocytes were subjected to immunofluorescence-FISH assay using anti-SYCP3, anti-H3K4m, and B chromosomes probes. Molecular homology of supernumeraries was confirmed by FISH and by its bivalent conformation in individuals with two of these chromosomes. In individuals with three Bs, these elements formed a bivalent and a univalent. Supernumerary and sex chromosomes exhibited H3K4m signals during pachytene contrasting with their heterochromatic and asynaptic nature, which suggest a more structural role than functional of this histone modification. The implications of this result are discussed in light of the homology, meiotic nuclear organization, and meiotic silencing of unsynapsed chomatin.

Determination of the chemical properties of water and sediments in agricultural land use by using energy dispersive X-ray fluorescence spectrometry

A técnica de espectrometria de fluorescência de raios X por energia dispersiva (EDXRF) foi aplicada em 29 amostras coletadas em um ano (jun/2012 a jul/2013) de monitoramento de qualidade da água do Rio Lajeado Pardo, afluente de um reservatório de captação de água para abastecimento, para avaliar a qualidade de 4 amostras de solos da floresta circundante e 6 amostras de sedimentos fluviais. Os teores elevados de Fe e Mn têm relação natural com os solos da região, já Cu, Zn, Ba e Cr, apesar de serem micronutrientes naturais do solo, podem ter enriquecimento proveniente do uso de fertilizantes e defensivos agrícolas. Segundo níveis estabelecidos pelas Diretrizes Canadenses de Qualidade dos Sedimentos para a Proteção da Vida Aquática e CONAMA nº 344/2000, as concentrações de Cr e Cu em sedimentos foram superiores ao nível acima do qual são observados efeitos severos à vida aquática. Em água doce, as concentrações de Fe, Zn, Cu e Mn foram superiores ao limite indicado pelas Diretrizes Canadenses de Qualidade da Água para a Proteção da Agricultura e Diretrizes Canadenses de Qualidade da Água para a Proteção de Vida Aquática. Não foram detectados os elementos Al, V, Zr, Sr, Cr, Y e Nb em água doce, estando a presença dos mesmos restrita aos solos e sedimentos de fundo do reservatório. O transporte médio anual de sedimentos foi estimado em 9,59 ton/ano.km2 . Entretanto, durante evento de precipitação pluviométrica, com vazão observada de 7,38 m³/s, se obteve a descarga máxima de 8,09 ton/dia.km2 de sólidos suspensos totais, um acréscimo de 307 vezes o valor médio diário transportado pelo rio

Uso combinado de curvas de permanência de qualidade e modelagem da autodepuração como ferramenta para suporte ao processo de enquadramento de cursos d-água superficiais

This study aimed to propose a methodology to support the establishment of Brazilian CONAMA 357/2005 rivers water quality classes based on quality parameters Flow-Duration Curves and self-purification analysis. To establish the different simulation water quality scenarios three sewage treatment conditions associated with distinct biochemical oxygen demand (BOD) removal efficiencies, two organic loads conditions and three time horizons (2014, 2020 and 2030) were considered. The QUAL-UFMG model for assessment of the self-purification capacity of the Pardo river, located in the south of Espirito Santo state, Brazil, was applied considering the BOD and dissolved oxygen (DO) parameters. In the simulations only river watershed sewage discharges were considered. BOD Flow-Duration Curves associated with environmental standards established by CONAMA Resolution 357/2005 for classes 1, 2 and 3 rivers were drawn. The results indicate the great importance of using river self-purification modeling for assessment of surface water body quality to establish river water classes. The results also indicate that a non-deterministic approach to water quality Flow-Duration Curves facilitates the decision-making process for the establishment of progressive water quality objectives.

Chemical Contamination of Water and Sediments in the Pardo River, São Paulo, Brazil

River pollution in urban areas may pose human health risks, due to the exposure to chemicals through direct contact, as well as the intake of contaminated fish, agricultural products and water. Pardo River is an important Brazilian water body which flows through two economically important states (São Paulo and Minas Gerais), and it is currently considered as a future drinking water supply option. In the present study, the concentrations of a number of herbicides (by Gas Chromatography with Nitrogen Phosphorous Detector-GC/NPD) and metals (by Inductively Coupled Plasma Mass Spectrometry-ICP/MS) were determined in samples of water and sediments collected along the Pardo River, São Paulo, Brazil, during wet and dry seasons. The presence of atrazine, ametrine, hexazinone and tebuthiuron was verified in water samples, being maximum levels 0.32, 0.27, 0.21 and 1.02μg/L, respectively. Cadmium, Cu and Zn maximum levels were above national thresholds according to the CONAMA Resolution No. 357/2005 (3.33, 14.6 and 408μg/L, respectively). In sediments, the highest concentrations were observed for Al and Mn (29,414 and 9,531mg/kg, respectively). In conclusion, the presence of environmental pollutants in water and sediments from the Pardo River is not insignificant, highlighting the potential risk for the population living nearby and in direct/indirect contact with river water. Metals detected above national thresholds may be coming from urban sewage, mining activities, fertilizers and industrial effluent. As our findings have important public health implications, we suggest a system of monitoring that needs to be implemented and can guide adequate actions to improve the resources quality.

Integrating three tools for the environmental assessment of the Pardo River, Brazil.

There is a growing need for strategic assessment of environmental conditions in river basins around the world. In spite of the considerable water resources, Brazil has been suffering from water quality decrease in recent years. Pardo River runs through Minas Gerais and São Paulo, two of the most economically important states in Brazil, and is being currently promoted as a future drinking water source. This study aimed at integrating three different tools to conduct a hydromorphological assessment focused on the spatial complexity, connectivity, and dynamism of the Pardo River, Brazil. Twelve sampling stretches were evaluated in four sampling campaigns, in dry and rainy seasons. In each stretch, permanent preservation areas (PPAs), hydromorphological integrity by rapid assessment protocol (RAP), and physicochemical parameters were qualified. The kappa coefficient was used to assess statistical agreement among monitoring tools. The PPA analysis showed that in all stretches, the vegetation was modified. RAP results revealed environmental deterioration in stretches located near human activities and less variability of substrates available for aquatic fauna and sediment deposition as well. Low values for dissolved oxygen in the river mouth were noted in the rainy season. Electrical conductivity was higher in stretches near sugarcane crops. The poor agreement (k<0.35) between the RAP and physicochemical parameters indicates that the tools generate different and complementary information, while they are not replaceable. Potential changes of the hydromorphological characteristics and variations in physicochemical indicators must be related to extensive PPA modification.

Spatial Response of Epilithic Diatom Communities to Downstream Nutrient Increases.

To monitor water quality and investigate relationships between downstream nutrient increases and diatom communities in the Pardo River Basin, Brazil, water and diatom samples were collected between 2005 and 2009. There were significant differences in diatom community composition among all river zones, with the greatest differences found between the upper and lower reaches. Significant changes were detected in relative abundances of diatom species and spatial structuring was evident. Dissolved oxygen, phosphates, turbidity, Eicherichia coli, and total dissolved solids were the most important variables shaping diatom communities, characterizing an organic pollution and eutrophication gradient. However, the hypothesis of sensitive species prevailing upstream and their gradual downstream replacement for more tolerant species was not confirmed because shifts in relative abundances of the same group of species in both the upper and lower reaches of the rivers were identified.

Development of the Trophic Water Quality Index (TWQI) for subtropical temperate Brazilian lotic systems.

This research aimed at developing the Trophic Water Quality Index (TWQI) for subtropical temperate Brazilian lotic systems based on a review of the indicative values of diatom species obtained using multivariate analysis techniques and considering the environmental gradient defined by a series of measured physical, chemical, and microbiological variables. Sampling was conducted from 2005 to 2009 in the Pardo River Hydrographic Basin, Rio Grande do Sul (RS), Brazil, and in the Andreas Stream Hydrographic Basin, RS, from 2012 to 2013. A total of 140 biological samples and 211 abiotic samples were collected. Data were analyzed by cluster analysis based on the Ward method and canonical correspondence analysis (CCA). The results indicated that total phosphate, turbidity, ammonia nitrogen, electrical conductivity, dissolved oxygen, and thermotolerant coliforms showed a significant correlation with the sample ordination made by CCA, in relation to a gradient of eutrophication. Eutrophication was operationally defined in a broad sense, including the problem of organic pollution and eutrophication of the water. The determination of the different tolerance degrees to eutrophication of the diatom taxa was used to assign trophic values of 1, 2.5, and 4 to species, corresponding to levels of low, medium, and high tolerance, respectively. By using the trophic values obtained for each diatom species, the TWQI constituted a new technological tool for environmental monitoring studies and showed a consistent, robust, and objective database for water quality assessment in subtropical temperate Brazilian lotic systems.