Variability of tropospheric hydroperoxides at a coastal surface site in Antarctica

The annual cycles of hydrogen peroxide (H2O2) and methylhydroperoxide (MHP) have been investigated at a remote site in Antarctica in order to study se asonal variations as well as chemical processes in the troposphere. The mea surements have been performed from March 1997 to January 1998 and in Februa ry 1999 at the German Antarctic research station Neumayer which is located at 70 degrees 39'S, 8 degrees 15'W. The obtained time series for hydrogen p eroxide and methylhydroperoxide in near-surface air represents the first al l-year measurements in Antarctica and indicates clearly the occurrence of s easonal variations. During polar night mean values of 0.054 +/- 0.046 ppbv (range < 0.03-0.11 ppbv) for hydrogen peroxide and 0.089 +/- 0.052 ppbv (ra nge < 0.05-0.14 ppbv) for methylhydroperoxide were detected. At the sunlit period higher Mixing ratios were found, 0.20 +/- 0.13 ppbv (range < 0.03-0. 91 ppbv) for hydrogen peroxide and 0.19 +/- 0.10 ppbv (range < 0.05-0.89 pp bv) for methylhydroperoxide. Occasional long-range transport of air masses from mid-latitudes caused enhanced peroxide concentrations at polar night. During the period of stratospheric ozone depletion we observed peroxide mix ing ratios comparable to typical winter levels. (C) 2000 Elsevier Science L td. All rights reserved.