Atmospheric ROOH in West Antarctica. Atmospheric Hydroperoxides in West Antarctica: Links to Stratospheric and Ozone and Atmospheric Oxidation Capacity

摘要

The troposphere above the West Antarctic Ice Sheet (WAIS) was sampled for hydroperoxides at 21 locations during 2-month-long summer traverses from 2000 to 2002, as part of U.S. ITASE (International Transantarctic Scientific Expedition). First time quantitative measurements using an HPLC method showed that methylhydroperoxide (MHP) is the only important organic hydroperoxide occurring in the Antarctic troposphere, and that it is found at levels ten times those previously predicted by photochemical models. During three field seasons, means and standard deviations for hydrogen peroxide (H202) were 321(+-)158 pptv, 650(+-)176 pptv and 33(+-)147 pptv. While MHP was detected, but not quantified in December 2000, levels in summer 2001 and 2002 were 317(+-)128 pptv and 304(+-)172.2 pptv. Results from firn air experiments and diurnal variability of the two species showed that atmospheric H202 is significantly impacted by a physical snow pack source between 76 and 90 OS, whereas MHP is not. We show strong evidence of a positive feedback between stratospheric ozone and H202 at the surface.