AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Secondary Organic Aerosols from Oil Spills: Wind Tunnel Evaporation and Flow Tube Oxidation Experiments
OMAR AMADOR-MUNOZ, Haofei Zhang, Pawel Misztal, Dave Worton, Greg Drozd, Allen H. Goldstein, University of California, Berkeley
Abstract Number: 691 Working Group: Aerosol Chemistry
Abstract The Deepwater Horizon (DWH) oil spill in the Gulf of Mexico in April-August of 2010 has unfortunately provided an important case for which we need to study production of secondary organic aerosol (SOA) from evaporating oil. Little is known about the atmospheric production of SOA from oil spills which can affect human health and climate. SOA is formed in the atmosphere through oxidation of gas phase compounds forming lower volatility products that can partition into the particulate phase. We studied SOA formation from evaporation of Macondo (MC 252) oil using a wind tunnel coupled to a flow tube oxidation reactor. Ozone, UV lights, and water vapor were used to make OH radicals. SOA mass was determined by a scanning mobility particle sizer. Species specific evaporation rates and gas phase photochemical products were observed using proton-transfer-reaction mass spectrometry (PTR-qMS and PTR-TOF-MS). Chemical characterization of particle phase organics were determined using comprehensive two dimensional gas chromatography with mass spectrometry utilizing both vacuum-ultraviolet ionization and electronic impact ionization (GCxGC-VUV/EI-ToF-MS). Oil evaporation experiments were carried out at wind speeds of 2 m/s over 30 hour periods. 25% of the SOA formed in 1 h, 50% in 2 h, 75% in 5 h and 90% in 15 h. An inverse linear relationship (r>-0.7) between some hydrocarbons (MW ≤ 100 Da) and SOA generation was observed in the first 90 min. After this time, a positive correlation (linear and logarithmic) was observed. Evaporation of hydrocarbons containing less than 16 carbon atoms (C16) produced around 90% of the oxidized hydrocarbons observed in the particle phase in GCxGC. We will show the implications on the production of SOA related with the number of carbons of several species with different reactivity, as well as the connection between diesel-related hydrocarbons and the hydroxyl radical reactivity.