Avaliação da concentração de dióxido de nitrogênio no entorno de uma Usina Termelétrica em Manaus - AM

Abstract

The burning of fossil fuels used for the production and use of electrical energy entails the release of many pollutants in the atmosphere. Among the pollutants noxious to the environment and people's health is cited nitrogen dioxide (NO2) to be freed in any kind of combustion whatever the type of fuel used, but are more likely to be formed during combustion of natural gas due to high temperature. The state of Amazonas is part of the isolated energy system, which consists of 80% of power plants which recently passed the conversion to natural gas. The study site of this research is the area of greatest concentration of thermal power plants in Manaus. This work was conducted to study the levels of NO2 concentration in the surroundings of one of these plants. The influence was investigated of meteorology at the locations of the sampling sites and the concentrations of NO2. The aim of this study was to monitor the concentration of NO2 from the burning of fossil fuels, using passive method. Samplers were installed at 15 points inside and around a thermal power plant, located in the neighborhood of Mauazinho in Manaus-AM in 2012. Sampling was performed in passive samplers containing o a cellulose filter impregnated with a solution of 5% triethanolamine, Teflon membrane and stainless steel mesh as diffusion barriers. Sets of eight passive samplers were exposed at each sampling point in the period May to October 2012. For quantification of mass of NO2 collected, used the solution of modified Griess-Saltzman and detection at UV-Vis spectrophotometer, with absorbance reading at a wavelength of 540 nm. The exposure time was 30 days. The results of the concentrations of NO2 passive samplers were validated with the data obtained with automated equipment obtained through a survey conducted in 2011, 1 km from the study site by Valois (2012). Were also compared with the standards of CONAMA and WHO. For the interpretation of NO2 and meteorological data were used exploratory techniques of multivariate ACP and AHA. The results found the average levels of NO2 concentration at 15 sampling points in 2012, was 206,86 ± 8,43 μg m-3. The minimum level of NO2 was 85,18 μg m-3 and a maximum of 747,93 μg m-3. Lower values of NO2 concentration are related to the rainy season (84,52 ± 68,08 mm) with lower average temperatures (27,78 ± 0,65 º C), humidity highest average (78,94 ± 10,43%), solar radiation (1362,50 kJ/m2) and insolation (192,4 h), and lowest in the driest months (50,50 ± 27,91 mm) from August to October with temperatures higher (29.09 ± 0.49 º C) and humidity lower (74,27 ± 31,06%), solar radiation (1450,81 kJ/m2) and insolation (215,0 h) higher. The concentration levels of NO2 are in accordance with the standards of CONAMA, but outside the limits set by WHO standards. The NO2 concentration data showed a heterogeneous behavior for each season and a standard deviation of 127,47 μg m-3 indicating dispersion among these. The use of passive samplers for the determination of the concentration of carbon dioxide was effective for obtaining reliable results