AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Simultaneous Bulk and Speciated Measurements of Low Volatility Organic Compounds in a Pine Forest during BEACHON-RoMBAS 2011
ARTHUR CHAN, Nathan Kreisberg, Yunliang Zhao, Thorsten Hohaus, Pedro Campuzano-Jost, John Jayne, Douglas Worsnop, Jose-Luis Jimenez, Susanne Hering, Allen H. Goldstein, University of California, Berkeley
Abstract Number: 532 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Organic aerosol (OA) is a major fraction of particulate matter, particularly in remote forested regions. Understanding its composition is essential to identifying the sources and processing, but its chemical complexity often limits such analysis. Here we present simultaneous bulk and speciated measurements of semivolatile and particle-phase organic compounds using a novel combined instrument (TAG-AMS) at Manitou Forest, CO during the BEACHON-RoMBAS 2011 campaign. This campaign is the first field deployment of the newly developed Semivolatile Thermal desorption Aerosol Gas chromatograph (SV-TAG), which provides on-line speciation of semivolatile organic compounds with bihourly time resolution, while the AMS provides bulk aerosol mass spectral analysis. The combined instrument provides quantitative organic and inorganic mass loadings, and elemental and PMF analysis of the bulk OA, simultaneously with detailed organic speciation. The data have been integrated so far to include a 2-week period of >100 compounds. These include both anthropogenic and biogenic compounds, with distinct time series. Highest concentrations of polycyclic aromatic hydrocarbons (PAHs) and alkanes were observed during the day, indicating influences of urban air masses at this field site. Speciated sesquiterpenes with molecular formula C15H24 (e.g. beta-caryophyllene and longifolene) were observed mostly at night. In addition, we present ambient measurements of a variety of low-volatility biogenic compounds, such as C15H22 sesquiterpenes (cuparene, calamenene) and diterpenoids (abietatrienes, retenes), at tens to hundreds of pg/m3. Many of these compounds have been identified in essential oils, but were observed in ambient air for the first time. They are likely reactive and contribute significantly to ozone loss and SOA formation, but are not included in current emission inventories. Using peak fitting analysis of high mass resolution data, we estimate that the total mass concentration of observed SVOCs (hydrocarbons between 13 and 25 carbons) is 0.1 - 0.3 ug/m3 during this field campaign.