Abstract
The concentration of carbonyl sulfide (OCS) has been determined in several preindustrial air samples extracted from a shallow ice core from Siple Dome, West Antarctica. The extraction of the air was carried out by shredding the core under vacuum, followed by analysis by gas chromatography with mass spectrometric detection. 11 ice core samples were analyzed, ranging in depth from 82.3 to 90.7 m. The ages assigned to OCS in the ice core samples range from 1616 to 1694 AD. The observed OCS mixing ratios range from 322.6 pptv to 442.3 pptv with a mean of 372.8 ± 37.2 pptv. These levels are significantly lower than the present day atmospheric mixing ratio of 500 pptv and suggest that the anthropogenic sources comprise approximately 25% of the present day OCS budget.
Highlights
[2] Carbonyl sulfide (OCS) is the most abundant tropospheric sulfur gas, with an average mixing ratio of approximately 500 pptv and an atmospheric lifetime of 4.3 years [Chin and Davis, 1995]
OCS is formed in the atmosphere from the photochemical oxidation of carbon disulfide (CS2) [Khalil and Rasmussen, 1984; Chin and Davis, 1993] and dimethylsulfide (DMS) [Barnes et al, 1994, 1996; Arsene et al, 2001]
We present the first results from an effort to extract and analyze OCS in preindustrial air from a shallow Antarctic ice core, from Siple Dome, West Antarctica
Summary
Received January 2002; revised 7 March 2002; accepted March 2002; published 15 May 2002. [1] The concentration of carbonyl sulfide (OCS) has been determined in several preindustrial air samples extracted from a shallow ice core from Siple Dome, West Antarctica. 11 ice core samples were analyzed, ranging in depth from 82.3 to 90.7 m. The ages assigned to OCS in the ice core samples range from 1616 to 1694 AD. The observed OCS mixing ratios range from 322.6 pptv to 442.3 pptv with a mean of 372.8 ± 37.2 pptv. These levels are significantly lower than the present day atmospheric mixing ratio of 500 pptv and suggest that the anthropogenic sources comprise approximately 25% of the present day OCS budget.
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