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A THIRTEEN-WEEK COMPARISON OF PASSIVE AND CONTINUOUS OZONE MONITORS AT FORESTED SITES IN NORTH-CENTRAL PENNSYLVANIA
Citation:
Impact/Purpose:
Our overall objective is to rapidly expand the perceived inexpensive application of passive sampling technology for O3 measurement from personal, indoor and/or limited (rural) outdoor monitoring to that of a network option or temporary network supplement for measuring the relative contribution of rural and urban ozone during episodic exceedances.
Description:
Ogawa passive 03 samplers were used in a 13-233k study (June 1-September 1, 1999) involving 11 forested and mountaintop sites in north-central Pennsylvania. Four of the sites were collocated with TECO model 49 O3 analyzers. A significant correlation (p<0.0001) was found for 24-hr average weekly 03 concentrations between the two methodologies at the four sites with collocated monitors. As expected, there were positive relationships between increasing elevation of the sites and increasing 03 concentrations. No 03 exposure patterns were found on a west-to-east or south-to-north basis; however, the area known for lower 03 exposures within a smaller subsection of the study area showed consistently lower 03 exposures. Preliminary results regarding relationships of symptom responses within 03-sensitive bioindicators are also presented with black cherry (Prunus serotina, Ehrh.) and common milkweed (Asclepias syriaca, L.) showing clear evidence of increasing injury with increasing O3 exposures. Due to the extremely dry conditions encountered in north-central Pennsylvania during the 1999 growing season, O3-induced symptoms were sporadic and quite delayed until late-season rains during the latter portion of the observations period.