Sources and Radiative Properties of Organosulfates in the Atmosphere

EPA Grant Number: R835401
Title: Sources and Radiative Properties of Organosulfates in the Atmosphere
Investigators: Stone, Elizabeth A
Institution: University of Iowa
EPA Project Officer: Hunt, Sherri
Project Period: April 1, 2013 through March 31, 2016
Project Amount: $300,000
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air


In this proposal, field measurements are designed to understand how secondary organic aerosol (SOA) forms in mixtures of biogenic and anthropogenic emissions and laboratory studies are proposed to evaluate its impacts on climate. The proposed study focuses on organosulfates that are significant components of ambient aerosol and unique to SOA formed under acidic conditions. Field-based measurements of organosulfates will be used to test the hypothesis that anthropogenic sulfur dioxide emissions impact SOA formation. Laboratory studies will further test the hypothesis that organosulfates are climate forcing agents. The primary objectives of the proposed work are to:

    i. Identify the anthropogenic and biogenic emission sources and atmospheric conditions that lead to organosulfate and SOA formation
    ii. Evaluate the direct and indirect radiative properties of organosulfates, including their light absorption, hygroscopicity, and cloud condensation nuclei activity.

The proposed study will improve the understanding of SOA formation, advance the analytical tools to study particulate matter, provide the first measurements of the climatically-relevant properties of organosulfates, and make significant contributions to the upcoming Southern Oxidant & Aerosol Study (SOAS).


To allow for organosulfate quantification in ambient aerosol, a novel set of biogenic organosulfate molecules will be generated using targeted organic synthesis. With these standards, a new analytical method will be developed using liquid chromatography and tandem mass spectrometry for the separation, identification, and quantification of organosulfates. Validated methodology will be applied to fine particulate matter collected in the Southeastern United States during the SOAS field campaign. Complementary chemical analysis will include measurements of organic carbon, sulfate and other inorganic ions, organic molecular markers for primary aerosol sources, and SOA tracers. Receptor-based source apportionment techniques will be applied to evaluate the sources of organic aerosol, SOA, and organosulfates. The direct and indirect radiative forcing properties of organosulfates will be evaluated with physical measurements of ultraviolet and visible light absorption, hygroscopicity, and cloud condensation nuclei activity.

Expected Results:

It is expected that these studies will provide mechanistic insight to how SOA forms under acidic conditions and how it impacts direct and indirect radiative forcing. Understanding the chemical and physical properties of SOA will lead to future advancements in the predictive capabilities of air quality and climate models.

Publications and Presentations:

Publications have been submitted on this project: View all 21 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 5 journal articles for this project

Supplemental Keywords:

mbient air, atmosphere, tropospheric, particulates, sulfates, organics, environmental chemistry, analytical, monitoring, modeling, measurement methods, southeast, EPA Region 4

Progress and Final Reports:

2013 Progress Report
2014 Progress Report
Final Report