Plínio Carlos Alvalá

DESENVOLVIMENTO DE METODOLOGIA PARA VALIDAÇÃO E ANÁLISE DE DADOS DE DIÓXIDO DE ENXOFRE (SO2) ATMOSFÉRICO SOBRE O CONTINENTE SUL-AMERICANO

This work describes the development of a methodology for validating the use of Brewer spectrophotometer for measuring the SO 2 total columns, from adaptations in its original calculation algorithm. The results obtained show the possibility of using Brewer spectrophotometer to measure the total columns of sulfur dioxide, with a gain in data quality, of great help to understand the behavior of this gas in the atmosphere with observations that can be used for model validation and calibration of satellites.

Residual emissions of CFC-11 and CFC-12 in the São Paulo metropolitan area

A study of atmospheric chlorofluorocarbons CCl3F (CFC-11) and CCl2F2 (CFC-12) was performed in the Metropolitan Region of Sao Paulo - MRSP (23.5oS; 46.6oW) during 2002. For the quantitative determination of the CFC concentration, a gas chromatograph with electron capture detector (ECD) was optimized with relative precision of 1.0%. In the MRSP, the observations of CFC-12 showed that there are large spatial and temporal variations in their concentrations (540.1 to 1395.8 pptv), while the CFC-11 concentrations did not show any statistically significant variation. Daily samplings were performed in June, July, August, September, November and December and showed that the emissions of CFC-12 were concentrated on weekdays (Monday to Friday), relating the emissions of this gas with its use in air conditioning and refrigeration systems of commercial and industrial buildings. The spatial variation observed in monthly campaigns in MRSP (April, May, June, July, August and September) and their matching with the predominant local wind direction evidencing the existence of a source region of CFC-12, located in the central area of the city. These results are indicative that emissions of CFC-12 are still significant. The monitoring of the mixing ratios of these gases in large cities like Sao Paulo can add to evaluate how the countries are following the Montreal Protocol, which restricts the production and trading of CFCs in developing countries, and schedule their banishment to 2010.