Measurements of organic trace gases including oxygenated volatile organic compounds at the high alpine site Jungfraujoch (Switzerland): Seasonal variation and source allocations

Abstract

At the high alpine site Jungfraujoch (Switzerland) mixing ratios of 21 oxygenated volatile organic compounds (OVOCs) and selected nonmethane hydrocarbons (NMHCs) have been measured by a newly developed two-stage double adsorbent system coupled to a gas chromatograph-mass spectrometer (GC-MS). In addition, formaldehyde was measured by the Hantzsch technique. Four measurement campaigns were performed once every season in 2005, providing for the first time a unique data set of OVOCs in the free troposphere of central Europe. The dominating OVOCs measured were acetone, methanol, formaldehyde and acetaldehyde, with mean mixing ratios of 622-867 ppt, 362-790 ppt, 303-505 ppt and 310-392 ppt, respectively. These compounds explained 95% of the measured organic compounds in summer and 83% in fall. Elevated mixing ratios in summer were observed for compounds with strong biogenic sources (e.g., methanol and acetone), whereas mainly anthropogenic compounds (e.g., ethanol and benzene) had higher mixing ratios during winter. Potential European source regions were estimated for the organic trace gases by combining the measured data with a statistical trajectory model. Northern Italy, southern France and southern and eastern Germany were identified as the main European contributors to the measured organic compounds at Jungfraujoch. Copyright 2008 by the American Geophysical Union.