Collection and Analysis of Firn Air From The South Pole, 2001
Abstract
In January 2001, we collected an archive of 20th century air from the firn at the South Pole. Samples were collected into separate pairs of 3L glass flasks for mea- surements of O2/N2, -15N-N2, and inert gases (Princeton, SIO) and carbon cycle gases including -13C-CO2 (Princeton and NOAA/CMDL); individual 3L stainless steel and additional glass flasks for measurements of halocarbons, N2O, SF6, and COS (NOAA/CMDL); large (33L) stainless steel canisters for maintaining an archive of air for future analyses; and a few cylinders each for measurement of -14C-CH4 (NIWA, CSIRO) and very low-level analyses of SF6 (SIO). Although it was hoped to obtain air dating back before the turn of the century, the analyses suggest that the earliest date was 1921 for CO2 and in the early 1900's for heavier gases such as methyl bromide or methyl chloride. This talk will compare the analyses of halocarbons in these recently collected samples to those of air in flasks sampled at the South Pole in 1995. We also will present some results for compounds not measured in the 1995 South Pole samples owing to a paucity of air. Measurements made of the same gases in the firn air at both ends of this six-year interval, along with real-time atmospheric measurements of the same gases, are useful in evaluating assumptions about diffusion in the firn. These measurements allow the direct calculation of diffusion coefficients at low temperatures, thus improving age estimates for firn air samples. Results show that, as expected, diffusion of gases in the firn is very close to molecular rates. Measurements of new gases will add to our existing histories established for the 20th century from analyses of firn air samples collected in both Greenland and Antarctica.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.1992B