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Assessment of “storage correction” required for in situ 14 CO production in air sample cylinders
Author(s) -
Lowe D. C.,
Levchenko V. A.,
Moss R. C.,
Allan W.,
Brailsford G. W.,
Smith A. M
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl014719
Subject(s) - environmental science , calibration , atmospheric sciences , in situ , nitrogen , earth's magnetic field , analytical chemistry (journal) , range (aeronautics) , meteorology , mineralogy , materials science , chemistry , environmental chemistry , geology , physics , organic chemistry , quantum mechanics , magnetic field , composite material
We draw attention to an effect that has the potential to compromise measurements of atmospheric 14 CO by the in situ production of 14 C in air sample cylinders. We present first experimental determinations of the size of this effect using measurements made on cylinders containing an air sample and a CO/nitrogen calibration gas stored in laboratories in New Zealand from a few months to 11 years. These data are collated with measurements made on air samples stored at Scott Base, Antarctica to determine a mean in situ production rate for 14 CO of 4.7 ± 0.5 molecules cm −3 yr −1 (STP) at sea level and in the latitude range 40–90° (geomagnetic) in a single floor laboratory. This rate is significant compared to observed annual cycles in 14 CO (typically 5–10 14 CO molecules cm −3 ) caused by OH variations and clearly has to be corrected for when 14 CO data are used to determine atmospheric OH distributions.