Surface ozone measurements in mountain forested areas using diffusive samplers

Abstract

The surface ozone levels were measured in the forested mountain areas of the Czech Republic in vegetation periods of 2004 and 2005 using the diffusive samplers. Commercially available Ogawa samplers, using filters coated with a nitrite-based solution, were applied. The ambient ozone oxidises the nitrite to nitrate, which after the exposure, is analysed by ion chromatography. The object of this study was to characterize a spatial and temporal distribution of ozone aiming to indicate within the mountain forested regions the risk areas as to the potential surface ozone impacts. Three research areas were established in forested regions adjacent to the country border. All of these areas are very important with regard to territorial landscape protection and tourism. They are forested, unpolluted with few minor emission sources located on their territory, mostly influenced by the long-range transport of pollutants (either of surface ozone or its precursors). The study has not yet been completed, and some preliminary results are presented here. The precision of replicate samples in both years was very good. The 2-week average concentrations for the Orlicke hory Mts. in 2004 were relatively high with the maximum of 70 ppb between July and August. The difference in the ambient ozone concentrations, calculated using the theoretical or empirical uptake rate, ranges between 2.3-3.9. This results in substantial underestimation of ambient ozone level if using the theoretical uptake rate, ca by a factor of 2-4. The diffusive samplers proved to be a very good tool for environmental studies in rural areas with complex terrain.