AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Laboratory Measurements of Total Suspended Organic Carbon: Technique Development and Application to Chamber Experiments
JOSHUA MOSS, Jesse Kroll, MIT
Abstract Number: 325 Working Group: Instrumentation and Methods
Abstract Secondary Organic Aerosol (SOA) composes a major fraction of particulate matter in the atmosphere and is principally formed through the oxidation of volatile organic compounds (VOCs). However, past bottom-up studies aimed at elucidating the underlying chemical mechanisms pertaining to SOA formation and evolution have been unable to fully identify and enumerate all SOA organic species, largely due to the extreme chemical complexity of the system and poorly constrained depositional losses to chamber walls. In order to provide a new “top-down” constraint on this chemical system, here we describe the measurement of Total Organic Carbon (TOC) for use in laboratory studies of SOA formation and oxidative aging. This work builds on an established technique for TOC measurement, involving the use of a palladium catalyst to fully oxidize VOCs to carbon dioxide, which to our knowledge has not been adapted for laboratory oxidation studies. A number of characterization studies, focused on measuring the oxidation efficiency for compounds spanning a wide range of volatilities (from volatile species in the gas phase to compounds present only in particles), will be described. Additionally, we describe the use of this technique within chamber SOA experiments, comparing measurements of TOC with results from a suite of instruments measuring gas- and particle-phase organic species. This “top-down” vs. “bottom-up” comparison provides new constraints on the extent of “carbon balance” measured in atmospheric oxidation studies.