Project Scientist

Research Interests:

  • AGAGE (Advanced Global Atmospheric Gases Experiment) http://agage.eas.gatech.edu/
  • Greenhouse gases
  • Halogenated trace gases
  • Ozone depleting compounds
  • Trace gas measurements (especially GC-FID/ECD/MSD)
  • Global warming
  • Top-down (measurement based) verification of bottom-up emission estimates
  • Atmospheric chemistry
  • Wildfire emissions
  • Long-range transport of pollutants

Degrees:

  • Diploma in Chemistry, University of Wuppertal
  • Doctor of Natural Sciences, Max Planck Institute for Chemistry, Mainz and Johannes Gutenberg University Mainz

Recent Publications

Deeds, DA, Kulongoski JT, Mühle J, Weiss RF.  2015.  Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: Observations in groundwaters along the San Andreas Fault. Earth and Planetary Science Letters. 412:163-172. AbstractWebsite

Abstract Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge ( C r e ; ∼30 fmol kg−1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1–9 times C r e ), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10–980 times C r e ) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20–100 km) suggests that the SAFS potentially emits ( 0.3 – 1 ) × 10 − 1 kg CF4 yr−1 to the Earth's surface. For comparison, the chemical weathering of ∼ 7.5 × 10 4 km 2 of granitic rock in California is estimated to release ( 0.019 – 3.2 ) × 10 − 1 kg CF4 yr−1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial–interglacial transitions.

Lunt, MF, Rigby M, Ganesan AL, Manning AJ, Prinn RG, O’Doherty S, Mühle J, Harth CM, Salameh PK, Arnold T, Weiss RF, Saito T, Yokouchi Y, Krummel PB, Steele PL, Fraser PJ, Li S, Park S, Reimann S, Vollmer MK, Lunder C, Hermansen O, Schmidbauer N, Maione M, Arduini J, Young D, Simmonds PG.  2015.  Reconciling reported and unreported HFC emissions with atmospheric observations. Proceedings of the National Academy of Sciences. 112(9):5927-5931. AbstractWebsite

We infer global and regional emissions of five of the most abundant hydrofluorocarbons (HFCs) using atmospheric measurements from the Advanced Global Atmospheric Gases Experiment and the National Institute for Environmental Studies, Japan, networks. We find that the total CO2-equivalent emissions of the five HFCs from countries that are required to provide detailed, annual reports to the United Nations Framework Convention on Climate Change (UNFCCC) increased from 198 (175–221) Tg-CO2-eq⋅y–1 in 2007 to 275 (246–304) Tg-CO2-eq⋅y–1 in 2012. These global warming potential-weighted aggregated emissions agree well with those reported to the UNFCCC throughout this period and indicate that the gap between reported emissions and global HFC emissions derived from atmospheric trends is almost entirely due to emissions from nonreporting countries. However, our measurement-based estimates of individual HFC species suggest that emissions, from reporting countries, of the most abundant HFC, HFC-134a, were only 79% (63–95%) of the UNFCCC inventory total, while other HFC emissions were significantly greater than the reported values. These results suggest that there are inaccuracies in the reporting methods for individual HFCs, which appear to cancel when aggregated together.

Hossaini, R, Chipperfield MP, Saiz-Lopez A, Harrison JJ, von Glasow R, Sommariva R, Atlas E, Navarro M, Montzka SA, Feng W, Dhomse S, Harth C, Mühle J, Lunder C, O'Doherty S, Young D, Reimann S, Vollmer MK, Krummel PB, Bernath GPFC.  2015.  Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol. Geophysical Research Letters. :n/a-n/a. AbstractWebsite

We have developed a chemical mechanism describing the tropospheric degradation of chlorine-containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS (ClyVSLS) between 2005 to 2013. By constraining the model with surface measurements of chloroform (CHCl3), dichloromethane (CH2Cl2), tetrachloroethene (C2Cl4), trichloroethene (C2HCL3) and 1,2-dichloroethane (CH2ClCH2Cl), we infer a 2013 ClyVSLS mixing ratio of 123 parts per trillion (ppt). Stratospheric injection of source gases dominates this supply, accounting for ~83% of the total. The remainder comes from VSLS-derived organic products, phosgene (COCl2, 7%) and formyl chloride (CHClO, 2%), and also hydrogen chloride (HCl, 8%). Stratospheric ClyVSLS increased by ~52% between 2005-2013, with a mean growth rate of 3.7 ppt Cl/yr. This increase is due to recent and ongoing growth in anthropogenic CH – the most abundant chlorinated VSLS not controlled by the Montreal Protocol.

Li, S, Kim J, Park S, Kim S-K, Park M-K, Muhle J, Lee G, Lee M, Jo CO, Kim K-R.  2014.  Source Identification and Apportionment of Halogenated Compounds Observed at a Remote Site in East Asia. Environmental Science & Technology. 48:491-498.: American Chemical Society Abstract

The sources of halogenated compds. in East Asia assocd. with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 halogenated compds. and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from Nov. 2007 to Dec. 2011 were analyzed by a pos. matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concns. of halogenated compds. obsd. at Gosan and corresponding concn.-based source contributions were also suggested: primary aluminum prodn. explaining 37% of total concn. enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC prodn. with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory anal. was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum prodn., solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF anal. results. The industry-based emission sources of halogenated compds. identified in this study help improve our understanding of the East Asian countries' industrial contributions to halogenated compd. emissions. [on SciFinder(R)]

Mahieu, E, Zander R, Toon GC, Vollmer MK, Reimann S, Mühle J, Bader W, Bovy B, Lejeune B, Servais C, Demoulin P, Roland G, Bernath PF, Boone CD, Walker KA, Duchatelet P.  2014.  Spectrometric monitoring of atmospheric carbon tetrafluoride (CF4) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate. Atmos. Meas. Tech.. 7:333-344.: Copernicus Publications AbstractWebsite
n/a
Hall, BD, Engel A, Mühle J, Elkins JW, Artuso F, Atlas E, Aydin M, Blake D, Brunke EG, Chiavarini S, Fraser PJ, Happell J, Krummel PB, Levin I, Loewenstein M, Maione M, Montzka SA, O'Doherty S, Reimann S, Rhoderick G, Saltzman ES, Scheel HE, Steele LP, Vollmer MK, Weiss RF, Worthy D, Yokouchi Y.  2014.  Results from the International Halocarbons in Air Comparison Experiment (IHALACE). Atmos. Meas. Tech.. 7:469-490.: Copernicus Publications AbstractWebsite
n/a