AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Link between Aerosol Liquid Water and Organosulfur Compounds in the Continental U.S.
ANNMARIE CARLTON, Thien Khoi Nguyen, Virendra Ghate, Rutgers University
Abstract Number: 418 Working Group: The Role of Water in Aerosol Chemistry
Abstract Organosulfate compounds are products of secondary organic aerosol formation. They are important sulfur reservoirs in the atmosphere and are found in fog, rain, and ambient particulate matter samples. Averaged across the U.S. at sites that are part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, these compounds comprise 5-10% of fine particle organic matter. In biogenically influenced areas of the eastern U.S., submicrometer particulate organic mass can be dominated (up to 65%) by organosulfates that have been found in laboratory studies to only form in aerosol liquid water. Despite their important contribution to the atmospheric particulate matter burden and the formation link to water, the relationship of organosulfates to ambient aerosol liquid water is poorly constrained. The latter is an abundant and ubiquitous component of atmospheric aerosols and influences a variety of critical atmospheric processes. Here we aim to better understand the spatial and temporal link between aerosol liquid water and organosulfates for different geographical regions across the continental U.S. We analyze discrepancies in collocated sulfur measurements at IMPROVE sites where both X-ray fluourescence (XRF) and ion chromatography (IC) techniques are used to estimate organosulfate contribution to fine particle mass. We employ the thermodynamic model ISORROPIA (v2.1) to estimate aerosol water mass concentrations at the same sites using measured speciated ion mass concentrations and NCEP North American Regional Reanalysis (NARR) meteorological data. We find that organosulfate contribution to organic mass is highest during the summer, corresponding with peak sulfur emissions and the highest aerosol water mass concentrations. Our findings suggest that discrepancies in collocated sulfur measurements are explained, in part, by aerosol water-mediated chemistry that forms organosulfates. These findings elucidate important feedbacks in anthropogenic-biogenic interactions that contribute to particle mass in the atmosphere.