Estudo das concentrações dos clorofluorcabonetos CFC-11 e CFC-12 na baixa atmosfera em regiões remotas, rurais e urbanas no Brasil. / Study of the chlorofluorocarbons 11 and 12 in the lower atmosphere in remote, rural and urban areas in Brazil.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

ABSTRACT Chlorofluorocarbons (CFCs) were intensively used for refrigeration, production of aerosols and foams. Presently, their production and trade are controlled, because of their role in ozone depletion. This work presents a study of atmospheric chlorofluorocarbons CCl3F (CFC-11) and CCl2F2 (CFC-12) in the lower troposphere of remote regions in Brazil (Barra de Maxaranguape - 6°S; 35°O; Campo Grande - 20.5°S; 54.6°O and Maringá - 23.4°S; 51.9°O), daily and spatial variations in urbanized areas (São Paulo - 23.5°S; 46.6°O and São José dos Campos - 23.2°S; 45.9°O). For quantitative determination of CFCs concentrations, a gas chromatograph with electron capture detector (ECD) was optimized. Surface data for both CFCs showed no latitudinal variation. The annual averages for 2002 were: Barra de Maxaranguape, CFC-11: 259.2 ± 4.1 pptv and CFC-12: 544.4 ± 3.5 pptv; Campo Grande, CFC-11: 257.6 ± 2.2 pptv and CFC-12: 543.7 ± 3.2 pptv; Maringá, CFC-11: 257.2 ± 2.4 pptv and CFC-12: 544.5 ± 3.6 pptv. The monthly averages of CFC-11 for Barra de Maxaranguape and Maringá showed a small seasonal variation, with minimum during winter (June/July). The observed CFC-12 concentrations at the three remote locations presented a more pronounced seasonal variation than that observed in CFC-11, with same time of minimum. In Barra de Maxaranguape the CFC-11 concentration showed a decreasing trend, with a rate of about 8 pptv/year, while the CFC-12 concentration did not show any annual variation. On the contrary, there is a large spatial and temporal variation in the concentration of CFC-12 in the urban areas, ranging from 551.1 pptv to 1,395.8 pptv.

ASSUNTO(S)

greenhouse effect clorofluorcarbonos emissão. key words: climate change mudança climática efeito estufa composição atmosférica atmospheric composition chlorofluorcarbons emission

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