Articles | Volume 23, issue 22
https://doi.org/10.5194/acp-23-14437-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-23-14437-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
22 Nov 2023
Research article |
| 22 Nov 2023
| 22 Nov 2023
pH dependence of brown-carbon optical properties in cloud water
Christopher J. Hennigan
CORRESPONDING AUTHOR
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Michael McKee
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Vikram Pratap
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Bryanna Boegner
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Jasper Reno
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Lucia Garcia
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Madison McLaren
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, 21250, USA
Sara M. Lance
Atmospheric Sciences Research Center (ASRC), University at Albany, Albany, 12226, USA
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Measurements of aerosol and gas composition were carried out at a land–water transition site near Baltimore, MD. Gas-phase ammonia concentrations were highly elevated compared to measurements at a nearby inland site. Our analysis reveals that NH2 was from both industrial and agricultural sources. This had a pronounced effect on aerosol chemical composition at the site, most notably contributing to episodic spikes of aerosol nitrate.
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Short summary
This study characterized the optical properties of light-absorbing organic compounds, called brown carbon (BrC), in atmospheric cloud water samples. In all samples, light absorption by BrC increased linearly with increasing pH. There was variability in the sensitivity of the absorption–pH relationship, depending on the degree of influence from fire emissions. Overall, these results show that the climate forcing of BrC is quite strongly affected by its pH-dependent absorption.
This study characterized the optical properties of light-absorbing organic compounds, called...
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