THE ISOTOPIC COMPOSITION OF TROPOSPHERIC OZONE IN 3 ENVIRONMENTS

Ground-level ozone (O-3) has been sampled from three environments: La Jolla and Pasadena, California, and White Sands Missile Range, New Mex ico, using recently developed techniques for cryogenically collecting and isotopically analyzing samples of atmospheric O-3. Significant iso topic variability is observed at each location, in addition to potenti ally important differences between the sampling locations. The isotopi c composition of O-3 is a sensitive indicator for the formation and de composition processes which have influenced the O-3 reservoir. Thus th e isotopic characterization of ground-level O-3 could provide a new so urce of information regarding atmospheric transformation mechanisms. T o date, the measured isotopic variability in ground-level O-3 shows no correlation with O-3 or NOx mixing ratios, meteorological parameters, or time of day. However, preliminary results show a correlation betwe en the pattern of isotopic fractionation and degree of photochemical c ontrol over the local O-3 budget at each sampling location. It should be noted that the conclusions presented are preliminary because of the relatively small data sets, particularly at the Pasadena and New Mexi co locations. However, we believe that the results of this research in dicate that the isotopic composition of tropospheric O-3 is variable a nd contains information which could be useful in the effort to underst and the tropospheric O-3 budget.