HYDROXYL RADICAL CONCENTRATION IN AMBIENT AIR AT A SEMIRURAL SITE ESTIMATED FROM 13-CO OXIDATION
In the context of a study of the formation of tropospheric ozone at a semirural site, a series of experiments have been performed to estimate the average OH radical concentration on sunny summer days. To this scope ambient air with added C**13O (+- 1 ppm) was irradiated in 2m**3 Teflon bags and C**13O decrease was measured by long path infrared absorption. Experiments were performed in Ispra a semirural site at 45 degrees N latitude in the period May 20th, July 26th 1983. NO, NO-2, O-3, water vapour, temperature and UV light intensity were followed during each experiment in the bags and in outside air. The average OH radical concentration was estimated from the results of thirteen experiments to be 2#8S10**6 molecules cm**-3 (averaged over all the days of the experiments and over 8 hours irradiation from 8am to 4 pm). An upper limit equal to 4 times 10**6 cm**-3 was also calculated. These values appear in fairly good agreement with results of direct measurements of OH concentration given in literature. The results of these and other experiments assign a small or negligible role to the contribution of carbon monoxide to the formation of tropospheric ozone observed at ground level in the Ispra area. The limits of the method will be discussed together with possible improvements.
Bibliographic Reference: 3RD EUROPEAN SYMPOSIUM ON PHYSICO CHEMICAL BEHAVIOUR OF ATMOSPHERIC POLUTANTS, VARESE (ITALY), APRIL 10-21, 1984 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 31422 ORA
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Record Number: 1989122055100 / Last updated on: 1987-01-01
Available languages: en