The Atmospheric Research Laboratory (ARL) at the University of Colorado Boulder’s Institute of Arctic and Alpine Research (INSTAAR) operates several analytical systems for qualitative and quantitative analyses of volatile organic compounds (VOC) in air samples. Since 2004, the ARL, in collaboration with the NOAA Global Monitoring Division, has been monitoring VOCs in weekly pairs of samples received from over 45 sites around the world. This is the most extensive global VOC monitoring currently operated around the world. A detailed program description is presented here.

On a second analytical system, VOCs and methane can be analyzed from glass flasks, Summa stainless steel canisters, and programmable flask packages. In recent years, these tools have been extensively applied in both background monitoring and research of VOC emissions from traffic, industrial operations, and oil and natural gas operations.

Services:

The ARL offers these VOC analyses to agencies and community members on a per sample or contract basis. We have ~25 years of experience in atmospheric VOC monitoring. We can provide guidance in sampling plans and make available sampling apparatus, glass flasks, and Summa canisters, or analyze VOC in whole air samples provided to us. We are capable of working with other collection methods on a case by case basis, as well.

Samples are analyzed using an automated instrument with drying/pre-focusing of  VOC in sample air followed by gas chromatography separation with mass spectrometry/flame ionization detection (GC-MS/FID). A wide range of VOC can be identified using the MS. Quantification is typically accomplished using the higher accuracy FID. Quantified chemical VOC species include saturated and unsaturated hydrocarbons, light alkanes, heavy alkanes, and aromatics.

Summa Cannisters                                                                                                       Back to Top

Summa Canisters are 6 liter stainless steel containers. We have a series of passive flow controllers that can be used for time-integrated sampling by gradually filling canisters over periods from 3 hours up to several days. Flow controlling regulators are attached to the top of the canister (see picture below). Programmable timers can be added to this sampling package to allow filling canisters only during certain time intervals or times of day. 

Programmable Flask Packages                                                                                   Back to Top

Programmable Flask Packages (PFPs) contain twelve 0.7 L borosilicate glass flasks, stacked in two rows of six. PFPs are filled using a programmable compressor package (PCP) that includes two pumps that control flow rates and the flasks filling pressure. A data logging and control system controls when the flasks open and close, and can store a sampling plan and fill pressure for all samples. These air samples are analyzed on the same analytical system as for the Summa cannisters.

Uncertainties and Precision                                                                                      Back to Top 

We maintain a series of quantitative calibration standards for high accuracy quantification of methane and VOCs. Standards include whole air and synthetic mixtures. We maintain several standards at higher than (typical) ambient VOC mole fractions for accurate quantification of elevated VOC that can be observed in the vicinity of oil and natural gas operations. Currently, nine standards are available with a wide range of VOC. Our calibration scale is regularly compared with national and international partners to ascertain our lab’s calibration scale. ARL has been audited two times by the World Calibration Centre for VOC. During both audits all reported VOC were quantified within the quality objectives of the World Meteorological Organization Global Atmospheric Watch.

Most of the VOC species are quantifiable at detection limits down to single parts per trillion levels (pptv), Measurement uncertainties for glass flasks, Summa canisters, and PFPs for C2-C6 alkanes are between 2–5% at mixing ratios >100 ppt, and ≤5 ppt for results <100 ppt. Measurement uncertainties are approximately 2x higher for acetylene and benzene. Methane quantification results have a ~0.3% uncertainty for single injections, and at <0.1% uncertainty for multiple runs.

Posters from our VOC monitoring work                                                                    Back to Top

Publications from our VOC monitoring work                                                        Back to Top

Helmig D., Rossabi S., Hueber J., Tans P., Montzka S.A., Masarie K., Thoning K., Plass-Duelmer C., Claude A., Carpenter L.J., Lewis A.C., Punjabi S., Reimann S., Vollmer M.K., Steinbrecher R., Hannigan J.W., Emmons L.K., Mahieu E., Franco B., Smale D., and Pozzer A. (2016) Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production, Nature Geosci, 9, 490-495. (link to article)

Oltmans S.J., Karion A., Schnell R.C., Pétron G., Sweeney C., Helmig D., Montzka S.A., Wolter S., Neff D., Miller B.R., Hueber J., Conely S., and Johnson B.J. (2016) O3, CH4, CO2, CO, NO2, and NMHC aircraft measurements in the Uinta Basin oil and gas development region under exceptional high ozone and non-ozone producing winter conditions. Elementa, in press.

Ahmadov R. et al. (2015) Understanding high wintertime ozone pollution events in an oil- and natural gas-producing region of the western US. Atmos. Chem. Phys. 15, 411-429. (Link to article)

Thompson C., Hueber J., and Helmig D. (2014) Influence of oil and gas emissions on ambient atmospheric non-methane hydrocarbons in residential areas of Northeastern Colorado. Elem. Sci. Anth. 3, 000035, 1-17, doi: 10.12952/journal.elementa.000035. (Link to article)

Edwards P.M. et al. (2014) High winter ozone pollution from carbonyl photolysis in an oil and gas basin. Nature 514, 351-354. (Link to article)

Oltmans S.J., Karion A., Schnel, R.C., Pétron G., Sweene, C., Wolter S., Neff D., Montzka S.A., Miller B. R., Helmig D., Johnson B.J., and Hueber J. (2014) A high ozone episode in winter 2013 in the Uinta Basin oil and gas region characterized by aircraft measurements, Atmos. Chem. Phys. Discuss. 14, 20117-20157, doi:10.5194/acpd-14-20117-2014. (Link to article)

Pétron G. et al. (2014) A new look at hydrocarbons emissions from oil and gas operations in the Colorado Denver-Julesburg Basin. J. Geophys. Res. 119, 6836-6852. (Link to article)

Edwards P.M. et al. (2013) Ozone photochemistry in an oil and natural gas extraction region during winter: simulations of a snow-free season in the Uintah Basin, Utah. Atmos. Chem. Phys. 13, 8955-8971. (Link to article)

Contact Information                                                                                                     Back to Top

Detlev Helmig
Institute of Arctic and Alpine Research
University of Colorado

4001 Discovery Drive
Boulder, CO 80303, USA
001 303 492-2509
detlev.helmig@colorado.edu