Carbonyl sulfide, carbon disulfide, methyl chloride, methyl bromide, ethane, propane, and n-butane measurements from two Greenland ice cores, 2004-2007

Seven short-lived atmospheric trace gases were measured in 25 ice core samples from Summit, Greenland to test the feasibility of trace gas analysis using Greenland ice core air. All analyses were conducted at the University of California, Irvine ice core research laboratory during 2004-2007. Samples were selected from contemporaneous sections of fluid- (GISP2D) and dry-drilled (GISP2B) ice cores to examine what effects using n-butyl acetate as the drill fluid would have on the measurements. The gases include three light alkanes, ethane (C2H6), propene (C3H6), and n-butane (n-C4H10); two methyl halides, methyl chloride (CH3Cl) and methyl bromide (CH3Br); and two sulfur compounds, carbonyl sulfide (COS) and carbon disulfide (CS2), with gas ages from 125 to 325 years before present (defined as 2000 CE). All trace gases were analyzed in the same sample air extracted from an approximately 500 grams (g) ice sample. Analyzed air was extracted from the ice core samples using a dry extraction technique. Gas analyses were conducted using a gas chromatogram-mass spectrometer system connected to a pre-concentration inlet system. Readers are referred to the accompanying paper for a detailed description of the methods. The results of this study showed that it was possible to analyze many trace gases in fluid- and dry-drilled ice samples. However, it appears that in situ production may significantly alter the levels of some trace gases in Greenland ice cores.