A new analysis system for whole air sampling: description and results from 2013 SENEX

Wednesday, 17 December 2014
Brian M Lerner1, Jessica Gilman2, Megan Dumas3, Dagen Hughes4, Alyssa Jaksich4, Courtney Dyan Hatch4, Martin Graus5, Carsten Warneke6, Eric C Apel7, Rebecca S Hornbrook8, John S Holloway9 and Joost A De Gouw10, (1)NOAA, Earth System Research La, Boulder, CO, United States, (2)NOAA ESRL, Boulder, CO, United States, (3)Stonehill College, Easton, MA, United States, (4)Hendrix College, Conway, AR, United States, (5)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (6)NOAA Boulder, Boulder, CO, United States, (7)National Center for Atmospheric Research, Boulder, CO, United States, (8)NCAR, Boulder, CO, United States, (9)CIRES, Boulder, CO, United States, (10)NOAA Earth System Research Lab, Boulder, CO, United States
Accurate measurement of volatile organic compounds (VOCs) in the troposphere is critical for the understanding of emissions and physical and chemical processes that can impact both air quality and climate.¬†Airborne VOC measurements have proven especially challenging due to the requirement of both high sensitivity (pptv) and short sample collection times (‚ȧ15 s) to maximize spatial resolution and sampling frequency for targeted plume analysis. The use of stainless steel canisters to collect whole air samples (WAS) for post-flight analysis has been pioneered by the groups of D. Blake and E. Atlas [Blake et al., 1992; Atlas et al., 1993].

For the 2013 Southeast Nexus Study (SENEX), the NOAA ESRL CSD laboratory undertook WAS measurements for the first time. This required the construction of three new, highly-automated, and field-portable instruments designed to sample, analyze, and clean the canisters for re-use. Analysis was performed with a new custom-built gas chromatograph-mass spectrometer system. The instrument pre-concentrates analyte cryostatically into two parallel traps by means of a Stirling engine, a novel technique which obviates the need for liquid nitrogen to reach trapping temperatures of -175C.

Here we present an evaluation of the retrieval of target VOC species from WAS canisters. We discuss the effects of humidity and sample age on the analyte, particularly upon C8+ alkane and aromatic species and biogenic species. Finally, we present results from several research flights during SENEX that targeted emissions from oil/natural gas production.