Navegando por Assunto "Reservoirs"

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Acesso aberto (Open Access)
Análise dos impactos da dinâmica de sólidos e de nutrientes na qualidade da água de ambiente lêntico utilizado no abastecimento de comunidades amazônicas
(Universidade Federal do Pará, 2012-08) SARAIVA, André Luis de Lima; PEREIRA, José Almir Rodrigues; http://lattes.cnpq.br/9918600634569244
The springs of Utinga, formed by the Bolonha and Água Preta lakes, are contained in an Área de Proteção Ambiental - APA and are used by the Companhia de Saneamento do Pará - COSANPA, to supply the population of the Região Metropolitana de Belém - RMB. These springs are formed by Guamá River, where water is captured and sent to the Água Preta lake by pumping, which in an artificial channel with gravity flow, feeds the Bolonha lake, and since it is pumped to the Estação de Tratamento de Água - ETA. The main problems of pollution / contamination of water sources appeared to advancing urban disordered, giving rise to the improper release of sewage and solid waste from neighborhoods, slums and housing estates close to the main springs. The objective of this study was to use tools to support monitoring and knowledge of water quality in the Água Preta lake, to prevent and / or correct degradation processes. These tools are multivariate analysis of abiotic parameters and chlorophyll a, nutrient balance and hydrodynamic modeling aiming to observe the dispersion of sediment transport. Samples were collected in surface water at three points strategically chosen to assess the anthropogenic influence in the Água Preta lake and sediments that are suspended matter carried into the lake. The sampling points were georeferenced using GPS (GARMIN Model) and the sampling of surface water were performed with the Van Dorn bottle 2.5 L and transported to the Laboratório de Química Ambiental (LQA), located at the Universidade Federal Rural da Amazônia, for further analysis. Samples were collected during the months of March, May, June, August, September and October in 2010, coinciding with periods of higher and lower rainfall. The data of abiotic parameters and chlorophyll a were analyzed by methods of descriptive statistics and principal component analysis. Analyses were also carried out analysis of the mass balance of water and nutrients and adopted the use of hydrodynamic model of the modeling program SisBAHIA (Sistema Base de Hidrodinâmica Ambiental), aimed to mimic the hydrodynamic conditions of the Água Preta lake during a year. Through these simulations were generated maps of surface currents to observe the different patterns of movement, since the use of models have played an important role in planning and development of alternative scenarios that include the proper diagnosis of the water systems in its structure, process and dynamics. The parameters studied showed variations during periods of lower and higher rainfall, higher contribution being found in point 2 in respect of turbidity, color, DO, nitrate, NT, chlorophyll a and suspended solids were found larger contribution in points 2. The other parameters (N -ammonia, BOD and PT) had contribution in points 1 and 3, indicating a source of organic pollution, due to domestic sewage, since there are nearby dumping of sewage. In the mass balance was found that both the PT and NID were influenced by the load of water river Guamá during the lower rainfall. While with high rainfall total phosphorus load was higher due to higher contribution from dewatering of sewage released into the reservoir. The retention time for the PT was 180 days and 536 days was NID. Through this balance could quantify the entry, retention and export of nutrients as well as to evaluate the potential for eutrophication of reservoirs. In the hydrodynamic model showed that the distribution of the module speed was identical for each month of the year, regardless of wind direction, with the riparian vegetation around that water environment this important role in reducing the speed modular surface of the water. However near the output channel of pond water was observed a change of speed 0.32 m /s in the rainy season and 0.28 m / s during the dry period that can be related to the precipitation. Furthermore, the input of water in the tank forms a vortex tending to sedimentation process, a fact observed in the bathymetry. The sedimentation at this point be given especially in periods with lower precipitation, because COSANPA increases the flow of water intake to maintain the level of the reservoir to supply the Região Metropolitana de Belém, providing the greatest contribution of suspended sediment, a fact observed with the parameters of turbidity, color and suspended solids, which have higher concentrations at this point and a decrease as they move away to step 3 (water outlet channel for the connection). These tools are of great importance for maintenance of the spring, since they will allow diagnosing the lake capacity tends of retain and remove nutrients as well as the process of the hydrodynamic circulation allowing check sites that can have a major and minor deposition of materials suspended in water column. Through this study will provide data that subsidizes the competent authorities the future and help in the conservation of other sources used to supply water to cities.
Acesso aberto (Open Access)
Aspectos limnoquímicos do reservatório da Usina Hidrelétrica de Tucuruí (PA): uma avaliação temporal entre 1986 e 2001
(Universidade Federal do Pará, 2003) SANTOS, Márcio José Moura dos; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The reservoir of the Tucuruí UHE, whose quota is around 72 m, holds a volume of about 50.8 million cubical meters and floods an area of 2.850 of Km2 . It has about 170 km length along its major axis (Main River) and maximum 40 km width. The average time of water residence in the reservoir is approximately 50 days, with a volume of only 3 % of non renewable water. The present work deals with the hydrochemistry of the following water systems: The Tocantins River (up- and downstream the dam) and the reservoir itself. They have been characterized during the year 2001 through horizontal and vertical distribution of the diverse physical, physico-chemical and chemical parameters analyzed, besides time-series evaluation in the period 1986 up to 2001, since the lake formation up to now. The study was carried after analysis of the following parameters: Temperature, Transparency and Total Suspended Solids – TTS, pH, Conductivity, Dissolved Oxygen, free CO2, Ca2+, Mg2+, Na+ , K+ , HCO3 - , Fe-total, P-Total, Ammonia and Nitrate. Studies of the trophic levels of the systems during the year 2001 have also been carried out following the Carlson´s Index of trophic state. It is based on three variables: transparency, a-chlorophyl and P-Total, in order to classify the water body in terms of its trophic level. The data used in this work were gently yielded by Eletronorte Company (Center for Environmental Research - CPA), besides our proper data collected in a fild work in November, 2001. Sampling stations have been established in the reservoir, either in the central body (M1 and M3 – old channel; MJV, MP and MR – outer zone) as in the Caraipé compartment (C1 and C2). In the Tocantins river, samples were collected upstream (M5) and downstream the dam (JT, NP, IT, MJ and cm). The results have shown that the system, as a whole, exhibit quite different hydrochemical characteristics (the central and outer part of the reservoir and up and downstream parts of the Tocantins river. According to studies conducted by Eletronorte, such difference is due to diverse hydrodynamic conditions of the reservoir. For instance, in the central body, the outer parts (MJV, MP and MR) have a hydraulic retention time ned for the rainy and dry seasons. It is also important to notice the role of the Tocantins river as supplier of micronutrients, mainly iron and P-total that will further get into the reservoir. Time-series analysis of the variables Total Suspended Solids, pH, Dissolved Oxygen, free CO2, P-Total and Ammonia did not show significant increasing or decreasing contents. pH and DO have also shown a narrow range of variation while the other parameters exhibited strong variations in the period studied. Finally, in 2001, it is possible to classify the study area a mesotrophic and oligotrophic in the dry and rainny seasons, respectivelly. The results have also shown that inside the reservoir, trophic levels are lower than those found in the Tocantins river (up and downstrean). Regarding only the reservoir, one finds that the Caraipé compartment has a greater trophic level than the central body.