AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Measurements of Particulate Chloride Using the FIGAERO-CIMS and ACSM
DONGYU S. WANG, Lea Hildebrandt Ruiz, University of Texas at Austin
Abstract Number: 398 Working Group: Aerosol Chemistry
Abstract Chlorine radicals can readily oxidize a wide range of atmospheric organic compounds. Studies have reported significant reactive chloride concentrations both inland and near coastal regions, where chlorine chemistry can dominate the initial oxidation of alkanes and other volatile organic compounds (VOCs) under certain conditions. Furthermore, there is an increasing number of reports of high particulate chloride concentrations in polluted environments; for example, as suggested by ambient measurements in megacities in China, India, and Mexico. Because of measurement challenges, the quantity and origin of particulate chloride remain highly uncertain.
We performed environmental chamber experiments, forming aerosol from a wide range of VOCs using chlorine as the primary oxidant. Aerosol particles were collected and analyzed using a Filter Inlet for Gases and AEROsols (FIGAERO) coupled to a High-Resolution Chemical Ionization Mass Spectrometer (CIMS) using water-hydronium and water-iodide clusters as ionization reagents. Aerosol composition was also measured using an Aerosol Chemical Speciation Monitor (ACSM). Challenges associated with ACSM chloride measurements were investigated using laboratory generated inorganic and organic aerosol, as well as recently collected ambient data from New Delhi, India.
Particulate chloride formation was observed with the FIGAERO-CIMS in select systems, including isoprene and alpha-pinene. In New Delhi, India, high concentrations of chloride were detected in the ACSM. Overall, our results suggest that chloride can constitute a significant fraction of the fine aerosol mass, and, despite some analytical challenges, existing instrumentation may be able to quantify this important component.