Our lab houses a system designed to analyze the concentration and stable isotopic composition of carbon monoxide (δ13CO and δC18O) on just a few nanograms of CO. Stable isotopes of CO are useful tracers of changes in CO sources. The system is currently in final stages of development and would ultimately be applicable for studies of the modern atmosphere as well as the ancient atmosphere (from ice cores). The system consists of:
- A new Isoprime 100, which is a state-of-the-art isotope ratio mass spectrometer
- A Peak Performer 1 system for analyzing CO concentration on as little as 1 cc of air
- A customized inlet / gas handling system (all-Pyrex construction) for extracting air from ice core samples, oxidizing CO to CO2 and transferring this CO-derived CO2 to the mass spectrometer
Methane, carbon monoxide, and carbon dioxide concentration
A new Picarro gas analyzer, capable of measuring CO2, CH4, CO, and H2O.
A Los Gatos Research (LGR) Ultra-Portable Greenhouse Gas Analyzer, for use both in the field and in the laboratory. Typical sample precision is on the order of ±0.5 ppm for CO2 and ± 3 ppb for CH4.
Carbon-14 of methane in the modern and ancient atmosphere
Our group has a one-of-a-kind field-deployable system for extracting ancient air from very large (≈1000 kg) samples of glacial ice. This enormous sample size is required to obtain the ≈20 µg of methane-derived carbon for a measurement of 14C by accelerator mass spectrometry (AMS). Details about the field extractions can be found in a blog post from the Taylor Glacier campaign. The lab also houses an all-Pyrex system for combusting the CH4 to CO2 in the sample air stream and collecting and purifying this CH4-derived CO2 for subsequent 14C analyses. The conversion of CO2 to graphite and AMS analyses are performed at an off-site laboratory.
Carbon-14 of carbon monoxide in air and ice
The same field deployable system and laboratory air-processing line that is used for 14C of CH4 can also be used to prepare samples for analyses of 14C in CO. This system has been used for analyses of in situ cosmogenic 14CO in ice. In addition, a new system to enable us to use 14CO in ice cores to reconstruct the atmospheric 14CO history was recently constructed and is currently being tested.
Carbon-14 of carbon dioxide in ice
Our laboratory is interested in using 14C of CO2 in ice as an absolute dating tool for ice cores, as well as in improving the understanding of production of 14CO2 directly in the ice by cosmic rays. For this purpose, we have developed a system for extracting CO2 from glacial ice via sublimation. Sublimation allows for 100% complete release of any in situ-produced 14CO2 that may be trapped within the ice grains. At the same time, it does so without melting the ice and avoids extraneous CO2 production that is associated with the liquid phase. The system is currently capable of sublimating ≈1.5 kg of ice in ≈8 hrs, which provides ≈20 µg of CO2-derived carbon for 14C analyses. A more in-depth description of the operation of the sublimation system can be found in our field blog entry.