University of Rochester Ice Core and Atmospheric Chemistry Lab

Analytical Capabilities

Carbon Monoxide concentration and stable isotope analyses on air and ice core samples

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 capable of measurements of CO stable isotopes in small air samples and we hope to ultimately use it to also make measurements of ice core samples. 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, ethane, carbon monoxide, and carbon dioxide concentration

A new Picarro G4302 Gas Scouter for field methane and ethane measurements. 

Two Picarro gas analyzers, 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 improved measurements of ¹⁴CO in ice cores, for reconstructions of the atmospheric  ¹⁴CO history, was recently developed and successfully used at Law Dome, Antarctica.

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.