Presentation Title

The role of oxidation on the water uptake of atmospherically relevant dicarboxylic acids

Presenter Information

Roshni MaparaFollow

Faculty Mentor

Paula K. Hudson

Start Date

18-11-2017 10:00 AM

End Date

18-11-2017 11:00 AM

Location

BSC-Ursa Minor 119

Session

Poster 1

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Aerosol particles are solid or liquid particles suspended in air and are generated from natural and anthropogenic sources. Aerosol that are produced from these sources can act as cloud condensation nuclei (CCN) that uptake water to form clouds that can be highly reflective, consisting of a large number of small particles and have a cooling effect on the Earth, or can rain. Dicarboxylic acids (DCA) are a particular aerosol of interest for their relatively high atmospheric concentrations and generation from both natural and anthropogenic sources. Given the chemical structure of DCA, the water uptake properties are strongly affected by carbon chain length where odd carbon chain length DCA are more hygroscopic than even. DCA also undergo atmospheric oxidation reactions by hydroxyl radicals that can change the carbon chain length resulting in changing hygroscopic (water uptake) properties. It is important to measure the hygroscopic properties of pure DCA aerosol and those that have been oxidized to understand the role of DCA as CCN and the effect on climate. In the laboratory, aqueous solutions of succinic acid, a C4 DCA, and various concentrations of hydrogen peroxide are photolyzed to simulate atmospheric oxidation reactions. The hygroscopic properties of particles generated from the resulting reaction mixtures are measured using a quartz crystal microbalance (QCM) as a function of increasing relative humidity. As relative concentrations of hydrogen peroxide are increased from one to ten times the amount of succinic acid, the degree of oxidation increases, and resulting reaction products are more hygroscopic than succinic acid. These results suggest that as DCA are oxidized in the atmosphere, a relatively non-hygroscopic succinic acid aerosol can be oxidized to form particles that have the ability to form highly reflective clouds that have a cooling effect. These measurements reduce uncertainties in the role DCA have on climate.

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Nov 18th, 10:00 AM Nov 18th, 11:00 AM

The role of oxidation on the water uptake of atmospherically relevant dicarboxylic acids

BSC-Ursa Minor 119

Aerosol particles are solid or liquid particles suspended in air and are generated from natural and anthropogenic sources. Aerosol that are produced from these sources can act as cloud condensation nuclei (CCN) that uptake water to form clouds that can be highly reflective, consisting of a large number of small particles and have a cooling effect on the Earth, or can rain. Dicarboxylic acids (DCA) are a particular aerosol of interest for their relatively high atmospheric concentrations and generation from both natural and anthropogenic sources. Given the chemical structure of DCA, the water uptake properties are strongly affected by carbon chain length where odd carbon chain length DCA are more hygroscopic than even. DCA also undergo atmospheric oxidation reactions by hydroxyl radicals that can change the carbon chain length resulting in changing hygroscopic (water uptake) properties. It is important to measure the hygroscopic properties of pure DCA aerosol and those that have been oxidized to understand the role of DCA as CCN and the effect on climate. In the laboratory, aqueous solutions of succinic acid, a C4 DCA, and various concentrations of hydrogen peroxide are photolyzed to simulate atmospheric oxidation reactions. The hygroscopic properties of particles generated from the resulting reaction mixtures are measured using a quartz crystal microbalance (QCM) as a function of increasing relative humidity. As relative concentrations of hydrogen peroxide are increased from one to ten times the amount of succinic acid, the degree of oxidation increases, and resulting reaction products are more hygroscopic than succinic acid. These results suggest that as DCA are oxidized in the atmosphere, a relatively non-hygroscopic succinic acid aerosol can be oxidized to form particles that have the ability to form highly reflective clouds that have a cooling effect. These measurements reduce uncertainties in the role DCA have on climate.