An outstanding issue has been the quantification of these processes. In particular, variation in the inadequately understood sink processes means that there will be a significant variation in the O3 atmospheric lifetime. The situation is exacerbated in the winter, when O3 lifetimes are enhanced. This grant utilized EPA funds to develop the ability to measure O3 isotopes at sufficiently high precision to address the issue of transport and removal mechanism by a new approach. The most difficult component of the proposed work was the development of a technique to quantitatively collect O3.
Ozone is collected with a cryogenic system.
At ambient O3 concentrations, a collection temperature and pressure of 55.0 0.1 K, 5.75 torr, respectively, is required. In this P-T regime, we have carefully established utilizing control experiments, that we attain efficient O3 trapping without O2 contamination. Xe are collected together, and xenon decreases the O3 isotopic measurement precision. This sieve trap is used as a separation media by warming to 153 K and allowing the O2 to release ahead of the xenon. At this purification level, our isotopic precision has been enhanced for d18O, d17O by nearly an order of magnitude.