Measurement Of Surface Ozone And Its Precursors In An Urban Area In South Brazil

摘要

Weekly and seasonal variations of surface ozone and their precursors - nitrogen oxides, carbon monoxide-associated with meteorological parameters (wind direction, temperature, solar radiation) -are reported. Measurements were performed continuously during 2006 at two sampling stations located in the metropolitan area of Porto Alegre, Brazil. Results have shown that O_3 concentrations remained almost constant between weekdays. Levels of NO_x precursors decreased especially on Sundays, due to lighter traffic. The seasonal variation has shown a maximum O_3 concentration during summer and spring while NO_x and NO_2 have maxima at the colder months. The daily cycle of highest ozone concentrations reveals a lower nightly level and an inverse relation between O_3 and NO_x, evidencing the photochemical formation of O3. There are seasonal variation and source heterogeneity.