Determinação de CD, PB, e TL em água produzida por HR-CS GF AAS após extração em ponto nuvem

Produced water is a major problem associated with the crude oil extraction activity. The monitoring of the levels of metals in the waste is constant and requires the use of sensitive analytical techniques. However, the determination of trace elements can often require a pre-concentration step. The objective of this study was to develop a simple and rapid analytical method for the extraction and pre-concentration based on extraction phenomenon cloud point for the determination of Cd, Pb and Tl in produced water samples by spectrometry of high resolution Absorption source continues and atomization graphite furnace. The Box Behnken design was used to obtain the optimal condition of extraction of analytes. The factors were evaluated: concentration of complexing agent (o,o-dietilditilfosfato ammonium, DDTP), the concentration of hydrochloric acid and concentration of surfactant (Triton X -114). The optimal condition obtained through extraction was: 0,6% m v-1 DDTP, HCl 0,3 mol L-1 and 0,2% m v-1 of Triton X - 114 for Pb; 0,7% m v-1 DDTP, HCl 0,8 mol L-1 and 0,2% m v-1 Triton X-114 for Cd. For Tl was evidenced that best extraction condition occurs with no DDTP, the extraction conditions were HCl 1,0 mol L-1 e 1,0% m v-1 de Triton X - 114. The limits of detection for the proposed method were 0,005 µg L-1 , 0,03 µg L-1 and 0,09 µg L-1 to Cd, Pb and Tl, Respectively. Enrichment factors Were greater than 10 times. The method was applied to the water produced in the Potiguar basin, and addition and recovery tests were performed, and values were between 81% and 120%. The precision was expressed with relative standard deviation (RSD) is less than 5%

Desenvolvimento de um sistema de captura de baixo custo destinado a determinação da cinemática humana

The motion capture is a main tool for quantitative motion analyses. Since the XIX century, several motion caption systems have been developed for biomechanics study, animations, games and movies. The biomechanics and kinesiology involves and depends on knowledge from distinct fields, the engineering and health sciences. A precise human motion analysis requires knowledge from both fields. It is necessary then the use of didactics tools and methods for research and teaching for learning aid. The devices for analysis and motion capture currently that are found on the market and on educational institutes presents difficulties for didactical practice, which are the difficulty of transportation, high cost and limited freedom for the user towards the data acquisition. Therefore, the motion analysis is qualitatively performed or is quantitatively performed in highly complex laboratories. Based is these problems, this work presents the development of a motion capture system for didactic use hence a cheap, light, portable and easily used device with a free software. This design includes the selection of the device, the software development for that and tests. The developed system uses the device Kinect, from Microsoft, for its low cost, low weight, portability and easy use, and delivery tree-dimensional data with only one peripheral device. The proposed programs use the hardware to make motion captures, store them, reproduce them, process the motion data and graphically presents the data.

Desenvolvimento de metodologia de extração e pré-concentração utilizando sistema microemulsionado para determinação de Cd, Co, Cu, Ni, Pb e Tl em águas naturais e produzidas por HR-CS AAS

The determination and monitoring of metallic contaminants in water is a task that must be continuous, leading to the importance of the development, modification and optimization of analytical methodologies capab le of determining the various metal contaminants in natural environments, because, in many cases, the ava ilable instrumentation does not provide enough sensibility for the determination of trace values . In this study, a method of extraction and pre- concentration using a microemulsion system with in the Winsor II equilibrium was tested and optimized for the determination of Co, Cd, P b, Tl, Cu and Ni through the technique of high- resolution atomic absorption spectrometry using a continuum source (HR-CS AAS). The optimization of the temperature program for the graphite furnace (HR-CS AAS GF) was performed through the pyrolysis and atomization curves for the analytes Cd, Pb, Co and Tl with and without the use of different chemical modifiers. Cu and Ni we re analyzed by flame atomization (HR-CS F AAS) after pre-concentr ation, having the sample introduction system optimized for the realization of discrete sampling. Salinity and pH levels were also analyzed as influencing factors in the efficiency of the extraction. As final numbers, 6 g L -1 of Na (as NaCl) and 1% of HNO 3 (v/v) were defined. For the determination of the optimum extraction point, a centroid-simplex statistical plan was a pplied, having chosen as the optimum points of extraction for all of the analytes, the follo wing proportions: 70% aqueous phase, 10% oil phase and 20% co-surfactant/surfactant (C/S = 4). After extraction, the metals were determined and the merit figures obtained for the proposed method were: LOD 0,09, 0,01, 0,06, 0,05, 0,6 and 1,5 μg L -1 for Pb, Cd, Tl, Co, Cu and Ni, re spectively. Line ar ranges of ,1- 2,0 μg L -1 for Pb, 0,01-2,0 μg L -1 for Cd, 1,0 - 20 μg L -1 for Tl, 0,1-5,0 μg L -1 for Co, 2-200 μg L -1 and for Cu e Ni 5-200 μg L -1 were obtained. The enrichment factors obtained ranged between 6 and 19. Recovery testing with the certified sample show ed recovery values (n = 3, certified values) after extraction of 105 and 101, 100 and 104% for Pb, Cd, Cu and Ni respectively. Samples of sweet waters of lake Jiqui, saline water from Potengi river and water produced from the oil industry (PETROBRAS) were spiked and the recovery (n = 3) for the analytes were between 80 and 112% confirming th at the proposed method can be used in the extraction. The proposed method enabled the sepa ration of metals from complex matrices, and with good pre-concentration factor, consistent with the MPV (allowed limits) compared to CONAMA Resolution No. 357/2005 which regulat es the quality of fresh surface water, brackish and saline water in Brazil.

Determinação da composição química de quatro variedades de feijão caupi (Vigna unguiculata L. Walp) cultivadas em solo potiguar

The cowpea (Vigna unguiculata L. Walp) is a major food crops in northeastern Brazil. In Rio Grande do Norte, the cowpea, vigna beans or cowpea, as it is known, has great socioeconomic importance as a source of nutrients in food, with great emphasis among agricultural products. To improve productivity and resistance to pests, two cultivars were developed exclusively by EMPARN (Agricultural Research Corporation of Rio Grande do Norte), for breeding. The samples were provided by EMPARN, two improved (Potiguar and Laugh year) and two landraces (Rib of beef and Canapu). The seeds were ground and made into flour samples and the determination of moisture and ash by graviméticos methods, lipids by Soxhlet extraction, fibers with determiner fiber, carbohydrates by difference and minerals by ICP-OES were performed except the match analyzed by UVvis. The results showed a high fiber content (55.55% and 55.32% and 50.04% improved samples and 50.32% creole samples) and protein (25.52% and 25.27% improved and 27 samples, 23% and 24.99% creole samples). Comparing the results of the mineral content, the improved cultivars stood out in relation to Ca, Co, P, Mg, Mo and Na. Creole cultivars showed better results for Cu, Cr (low), Fe, Mn, Ni, K and Zn. The results will be important in future nutritional research and to build a table of Brazilian chemical composition of foods.

Produção de filtrantes ativados a partir de aproveitamento de resíduos: uma proposta para a proteção respiratória ocupacional

A Proteção Respiratória Ocupacional é atualmente uma exigência legal do Ministério do Trabalho e Emprego para garantia da saúde e segurança de milhares de trabalhadores que labutam com exposição habitual a substâncias nocivas que possam ocasionar doenças ocupacionais por inalação de ar contaminado no local de trabalho, cuja principal via de penetração no organismo humano é o Sistema Respiratório. Carvões ativados são materiais obtidos a partir de fontes carbonáceas e utilizados como elemento tecnológico filtrante nos equipamentos destinados a proteção respiratória individual. Fomentada por esse contexto, e visando potencializar conceitos de eco-eficiência e sustentabilidade em produção de materiais, este trabalho destina-se a produção de carvão ativado com potencial filtrante a partir de um rejeito agrícola abundante na região Nordeste do Brasil através de uma rota que favorece carbonização e ativação simultâneas, seguido de neutralização térmica. A biomassa precursora foi caracterizada por Ensaios padrões para determinação do teor de umidade e cinzas, Análise Química Elementar, Análises Térmicas (TG e DSC) e Distribuição Granulométrica por difração a laser. As amostras de carvões ativos sintetizadas foram caracterizadas por Difração de Raios X (DRX), Medidas de área específica por BET, Microscopia Eletrônica de Varredura (MEV), Análise assistida com ultravioleta visível e Redução à Temperatura Programada (TPR) por Amônia. A rota empregada favorece uma tecnologia alternativa para o aproveitamento de resíduos e aplicável para a Proteção Respiratória Ocupacional. A atmosfera de queima influencia diretamente na produção. A temperatura de carbonização variou conforme a estabilidade térmica da amostra. A cristalinidade, morfologia, teor mineralógico, área superficial específica e a adsorção em fase líquida e gasosa variaram em função da interação do resíduo precursor com o tipo e concentração de ácido utilizado. Os ensaios de adsorção demonstraram a efetividade da ativação segundo a rota experimental proposta. O potencial catalítico dos materiais produzidos para uso em máscaras respiratórias foi evidenciado pelo ensaio de TPR. O processo de produção estudado se mostrou eficaz para obtenção dos carvões promovendo processamentos e aplicações mais nobres para materiais cujo uso tem sido restrito a meras aplicações primárias ou descarte, mas cujo potencial tecnológico é amplo, empreendedor, sustentável, viável em escala industrial e de baixo custo.

Determinação da condutividade do solo para agricultura: uma metodologia utilizando propagação de ondas AM

Agriculture is an essential activity to the human development, the tendency is that their need to increase according to the increase in world population. It is very important to take the maximum performance that is possible of each land without degrading it, a frequently monitoring is essential for the best performance. The purpose of this work is, nondestructively, to monitor the surface electrical conductivity of the soil in a demarcated area, as on a plantation, using low frequency radio waves. The conductivity is directly linked to the amount of water in the area and nutrients, therefore a periodic or even permanent monitoring increases significantly the efficient of the use of the soil. They will be used long-wave radio transmission or medium whose main characteristic to spread over the surface of the earth. It is possible to choose an AM radio with location, frequency and power of the transmission known or generate the signal. The studied method computes the conductivity of the ground in a straight line between two measured points, so it can be used in smaller or larger size fields. Measurements were carried out using an electromagnetic field strength analyzer. The data obtained in the measurements are processed by a numerical calculation program, in our case Matlab. It is concluded that the recommendations of the ITU (International Telecommunication Union) on the conductivity of soil in Brazil is far from reality, on some routes the recommendations indicate the use of the electrical conductivity of the soil 1 mS/m, while the measurements was found 19 mS/m. With the method described a precision farmer, once initial research for about a year, can monitor the humidity and salinity of the land, with the ability to predict the area and the most suitable time for irrigation and fertilization, making management more efficient and less expensive, while optimizing water use, natural resource increasingly precious.

Aplicação e otimização de métodos eletroquímicos combinados para remoção e determinação de cromo hexavalente em efluentes simulados

Hexavalent chromium is a heavy metal present in various industrial effluents, and depending on its concentration may cause irreparable damage to the environment and to humans. Facing this surrounding context, this study aimed on the application of electrochemical methods to determine and remove the hexavalent chromium (Cr6+) in simulated wastewater. To determine was applied to cathodic stripping voltammetry (CSV) using ultra trace graphite electrodes ultra trace (work), Ag/AgCl (reference) and platinum (counter electrode), the samples were complexed with 1,5- diphenylcarbazide and then subjected to analysis. The removal of Cr6+ was applied electrocoagulation process (EC) using Fe and Al electrodes. The variables that constituted the factorial design 24, applied to optimizing the EC process, were: current density (5 and 10 mA.cm-2), temperature (25 and 60 ºC), concentration (50 and 100 ppm) and agitation rate (400 and 600 RPM). Through the preliminary test it was possible the adequacy of applying the CSV for determining of Cr6+, removed during the EC process. The Fe and Al electrodes as anodes sacrifice showed satisfactory results in the EC process, however Fe favored complete removal in 30 min, whereas with Al occurred at 240 min. In the application of factorial design 24 and analysis of Response Surface Methodology was possible to optimize the EC process for removal of Cr6+ in H2SO4 solution (0.5 mol.L-1), in which the temperature, with positive effect, was the variable that presented higher statistical significance compared with other variables and interactions, while in optimizing the EC process for removal of Cr6+ in NaCl solution (0.1 mol.L-1) the current density, with positive effect, and concentration, with a negative effect were the variables that had greater statistical significance with greater statistical significance compared with other variables and interactions. The utilization of electrolytes supports NaCl and Na2SO4 showed no significant differences, however NaCl resulted in rapid improvement in Cr6+ removal kinetics and increasing the NaCl concentration provided an increase in conductivity of the solution, resulting in lower energy consumption. The wear of the electrodes evaluated in all the process of EC showed that the Al in H2SO4 solution (0.5 mol.L-1), undergoes during the process of anodization CE, then the experimental mass loss is less than the theoretical mass loss, however, the Fe in the same medium showed a loss of mass greater experimental estimated theoretically. This fact is due to a spontaneous reaction of Fe with H2SO4, and when the reaction medium was the NaCl and Na2SO4 loss experimental mass approached the theoretical mass loss. Furthermore, it was observed the energy consumption of all processes involved in this study had a low operating cost, thus enabling the application of the EC process for treating industrial effluents. The results were satisfactory, it was achieved complete removal of Cr6+ in all processes used in this study.

Determinação de recomendações bioclimáticas para habitação de interesse social de quatro climas do Rio Grande do Norte

Recomendações projetuais baseadas no clima são fontes importantes de diretrizes para os arquitetos. Uma das formas de obtenção dessas recomendações é por meio de normas, como a NBR 15220 (ABNT, 2005), que agrupa as cidades em zonas homogêneas quanto as estratégias sugeridas. O zoneamento bioclimático brasileiro divide o território do Rio Grande do Norte em duas zonas, a ZB 7 e ZB 8, que possuem algumas recomendações distintas, como aberturas grandes e vedações leves para a região litorânea contra aberturas pequenas e vedações pesadas para a região semiárida. Entretanto, outras configurações climáticas estão presentes no RN e não possuem clara recomendação. Este é o caso das regiões serranas e das regiões intermediárias entre o litoral e a região semiárida. Em virtude disso, este estudo visa encontrar recomendações bioclimáticas para habitações de interesse social nessas quatro condições climáticas. Para tanto, utilizou-se ferramenta computacional para realização de simulações das condições térmicas de três tipos de habitações populares - alongada, ramificada e compacta - e das seguintes estratégias: presença ou ausência de ventilação natural e sombreamento, massa térmica leve ou pesada, e Fator de Calor Solar alto ou baixo. Essas simulações foram realizadas para quatro condições climáticas do estado. Foram analisados os desempenhos de cada caso para identificar as estratégias e tipos de habitação recomendados para cada clima. De maneira geral, nos climas deNatal, Mossoró e Caicó viu-se que habitações com FCS baixo e com presença de ventilação natural possuem os melhores desempenhos. No clima de Areia, a ausência de ventilação aliada ao baixo FCS é que produziu os melhores desempenhos. O sombreamento melhora o desempenho nas cidades de clima quente, mas aumenta as horas com desconforto ao frio em Areia. A massa térmica varia de acordo com as demais estratégias, tendo casos em que habitações com massa térmica alta possuem melhores desempenhos que outros casos com massa térmica baixa. Por fim, viu-se que as estratégias para Natal, Caicó e Mossoró são bem semelhantes, com a recomendação de ventilação natural, FCS baixo nas vedações e sombreamento. Para Areia, a recomendação é não ventilar, ter FCS baixo e massa térmica alta.

Determinação de recomendações bioclimáticas para habitação de interesse social de quatro climas do Rio Grande do Norte

Recomendações projetuais baseadas no clima são fontes importantes de diretrizes para os arquitetos. Uma das formas de obtenção dessas recomendações é por meio de normas, como a NBR 15220 (ABNT, 2005), que agrupa as cidades em zonas homogêneas quanto as estratégias sugeridas. O zoneamento bioclimático brasileiro divide o território do Rio Grande do Norte em duas zonas, a ZB 7 e ZB 8, que possuem algumas recomendações distintas, como aberturas grandes e vedações leves para a região litorânea contra aberturas pequenas e vedações pesadas para a região semiárida. Entretanto, outras configurações climáticas estão presentes no RN e não possuem clara recomendação. Este é o caso das regiões serranas e das regiões intermediárias entre o litoral e a região semiárida. Em virtude disso, este estudo visa encontrar recomendações bioclimáticas para habitações de interesse social nessas quatro condições climáticas. Para tanto, utilizou-se ferramenta computacional para realização de simulações das condições térmicas de três tipos de habitações populares - alongada, ramificada e compacta - e das seguintes estratégias: presença ou ausência de ventilação natural e sombreamento, massa térmica leve ou pesada, e Fator de Calor Solar alto ou baixo. Essas simulações foram realizadas para quatro condições climáticas do estado. Foram analisados os desempenhos de cada caso para identificar as estratégias e tipos de habitação recomendados para cada clima. De maneira geral, nos climas deNatal, Mossoró e Caicó viu-se que habitações com FCS baixo e com presença de ventilação natural possuem os melhores desempenhos. No clima de Areia, a ausência de ventilação aliada ao baixo FCS é que produziu os melhores desempenhos. O sombreamento melhora o desempenho nas cidades de clima quente, mas aumenta as horas com desconforto ao frio em Areia. A massa térmica varia de acordo com as demais estratégias, tendo casos em que habitações com massa térmica alta possuem melhores desempenhos que outros casos com massa térmica baixa. Por fim, viu-se que as estratégias para Natal, Caicó e Mossoró são bem semelhantes, com a recomendação de ventilação natural, FCS baixo nas vedações e sombreamento. Para Areia, a recomendação é não ventilar, ter FCS baixo e massa térmica alta.

Utilização de sismos regionais para a determinação de um modelo 1D de velocidades da onda P na Província Borborema - NE do Brasil

In this work it was performed a study to obtain parameters for an 1D regional velocity model for the Borborema Province, NE Brazil. It was used earthquakes occurred between 2001 and 2013 with magnitude greater than 2.9 mb either from epicentres determined from local seismic networks or by back azimuth determination, when possible. We chose seven events which occurred in the main seismic areas in the Borborema Province. The selected events were recorded in up to 74 seismic stations from the following networks: RSISNE, INCT-ET, João Câmara – RN, São Rafael – RN, Caruaru - PE, São Caetano - PE, Castanhão - CE, Santana do Acarau - CE, Taipu – RN e Sobral – CE, and the RCBR (IRIS/USGS—GSN). For the determination of the model parameters were inverted via a travel-time table and its fit. These model parameters were compared with other known model (global and regional) and have improved the epicentral determination. This final set of parameters model, we called MBB is laterally homogeneous with an upper crust at 11,45 km depth and total crustal thickness of 33,9 km. The P-wave velocity in the upper crust was estimated at 6.0 km/s and 6.64 km/s for it lower part. The P-wave velocity in the upper mantle we estimated at 8.21 km/s with an VP/VS ratio of approximately 1.74.

Utilização de sismos regionais para a determinação de um modelo 1D de velocidades da onda P na Província Borborema - NE do Brasil

In this work it was performed a study to obtain parameters for an 1D regional velocity model for the Borborema Province, NE Brazil. It was used earthquakes occurred between 2001 and 2013 with magnitude greater than 2.9 mb either from epicentres determined from local seismic networks or by back azimuth determination, when possible. We chose seven events which occurred in the main seismic areas in the Borborema Province. The selected events were recorded in up to 74 seismic stations from the following networks: RSISNE, INCT-ET, João Câmara – RN, São Rafael – RN, Caruaru - PE, São Caetano - PE, Castanhão - CE, Santana do Acarau - CE, Taipu – RN e Sobral – CE, and the RCBR (IRIS/USGS—GSN). For the determination of the model parameters were inverted via a travel-time table and its fit. These model parameters were compared with other known model (global and regional) and have improved the epicentral determination. This final set of parameters model, we called MBB is laterally homogeneous with an upper crust at 11,45 km depth and total crustal thickness of 33,9 km. The P-wave velocity in the upper crust was estimated at 6.0 km/s and 6.64 km/s for it lower part. The P-wave velocity in the upper mantle we estimated at 8.21 km/s with an VP/VS ratio of approximately 1.74.

Efeito de diferentes divisões territoriais na flutuação aleatória de indicadores socioeconômicos relacionados à determinação social da saúde

This research aimed to analyse the effect of different territorial divisions in the random fluctuation of socio-economic indicators related to social determinants of health. This is an ecological study resulting from a combination of statistical methods including individuated and aggregate data analysis, using five databases derived from the database of the Brazilian demographic census 2010: overall results of the sample by weighting area. These data were grouped into the following levels: households; weighting areas; cities; Immediate Urban Associated Regions and Intermediate Urban Associated Regions. A theoretical model related to social determinants of health was used, with the dependent variable Household with death and as independent variables: Black race; Income; Childcare and school no attendance; Illiteracy; and Low schooling. The data was analysed in a model related to social determinants of health, using Poisson regression in individual basis, multilevel Poisson regression and multiple linear regression in light of the theoretical framework of the area. It was identified a greater proportion of households with deaths among those with at least one black resident, lower-income, illiterate, who do not attend or attended school or day-care and less educated. The analysis of the adjusted model showed that most adjusted prevalence ratio was related to Income, where there is a risk value of 1.33 for households with at least one resident with lower average personal income to R$ 655,00 (Brazilian current). The multilevel analysis demonstrated that there was a context effect when the variables were subjected to the effects of areas, insofar as the random effects were significant for all models and with different prevalence rates being higher in the areas with smaller dimensions - Weighting areas with coefficient of 0.035 and Cities with coefficient of 0.024. The ecological analyses have shown that the variable Income and Low schooling presented explanatory potential for the outcome on all models, having income greater power to determine the household deaths, especially in models related to Immediate Urban Associated Regions with a standardized coefficient of -0.616 and regions intermediate urban associated regions with a standardized coefficient of -0.618. It was concluded that there was a context effect on the random fluctuation of the socioeconomic indicators related to social determinants of health. This effect was explained by the characteristics of territorial divisions and individuals who live or work there. Context effects were better identified in the areas with smaller dimensions, which are more favourable to explain phenomena related to social determinants of health, especially in studies of societies marked by social inequalities. The composition effects were better identified in the Regions of Urban Articulation, shaped through mechanisms similar to the phenomenon under study.

Uma proposta de slam com determinação de informações geométricas do ambiente

PEDROSA, Diogo P. F. ; MEDEIROS, Adelardo A. D. ; ALSINA, Pablo J. . Uma Proposta de SLAM com Determinação de Informações Geométricas do Ambiente. In: CONGRESSO BRASILEIRO DE AUTOMÁTICA, 16, Salvador, BA, 2006. Anais... Salvador: CBA, 2006. v. 1. p. 1704-1709

Ciência, determinação e arte: os quadrados mágicos e a composição

Serão analisados aspectos históricos e estruturais dos quadrados mágicos e apresentados os materiais resultantes dessa investigação para efeito da composição de uma obra para coro, solistas e orquestra, a Paixão . O quadrado mágico, um dispositivo de características de construção matemáticas, adquiriu contornos místicos ao longo da história, por suas propriedades de simetria e beleza. O processo criativo dentro de uma perspectiva determinística, procura analisar o papel de estruturas pré-estabelecidas para a obtenção de materiais destinados a integrar o repertório de elementos pré-composicionais.

Caracterização limnológica e determinação da capacidade suporte do reservatório mendubim, (Rio Grande do Norte) para o cultivo de peixes em tanques-rede

The aims of this study were: i) assessing the trophic state of the Mendubim reservoir (semi-arid, Rio Grande do Norte, Brazil; 05° 38 99,0 S 36°55 98,0 W) based on chlorophyll-a, total phosphorus and nitrogen concentrations and water transparency; ii) relating the patterns of temporal variation of zooplankton and phytoplankton to the trophic state of the reservoir and iii) investigating the carrying capacity of the reservoir for cage fish farming. The samplingwas done monthly from July 2006 to July 2007 in three stations at the reservoir: next to the dam (barrage), in the central region and in the mouth of the main tributary. The abiotic and biotic variables analyzed were: Secchi depth, volatiles and fixed suspended solids, chlorophyll-a, total phosphorus and nitrogen, TN:TP ratio and mesozooplankton and phytoplankton composition and biomass. The results showed that the reservoir can be considered as mesotrophic with mean concentrations of total nitrogen, phosphorus and chlorophyll-a equal to 1711, 1 μg.L-1, 30,8 μg.L-1 and 5,62 μg.L-1 respectively. The Cyanophyceae class was the most representative in terms of density, with the presence of potentially toxic species such as Microcystis aeruginosa, Planktothrix planctonica, Cylindrospermopsis raciborskii, Aphanizomenon sp. ,Aphanocapsa delicatissima and Pseudanabaena acicularis. Among the zooplankton, the genus Notodiaptomus presented the largest biomass values. Overall, our results show that the light limitation should explain the weak relationship between chlorophyll-a and total phosphorus and nitrogen concentrations. We concluded that the water of Mendubim reservoir is suitable for intensive fish cage aquaculture. Based on the carrying capacity calculations for this reservoir, we found that the maximum sustainable yield of tilapias in cages in the reservoir is 126 ton per year assuming a factor of food conversion of 1.5: 1.0 and a phosphorus content in the fish food of 1%