| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | April 25, 2017 |
| Latest Amendment Date: | July 21, 2017 |
| Award Number: | 1663726 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Sylvia Edgerton
sedgerto@nsf.gov (703)292-8522 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | May 1, 2017 |
| End Date: | April 30, 2021 (Estimated) |
| Total Intended Award Amount: | $18,822.00 |
| Total Awarded Amount to Date: | $18,822.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
500 W UNIVERSITY AVE EL PASO TX US 79968-8900 (915)747-5680 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
591 West University Avenue El Paso TX US 79968-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Atmospheric Chemistry |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT 01001920DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Droughts mobilize natural dust from salt playas that can react with nitrogen oxides, criteria pollutants that are emitted by combustion sources. This reaction releases chlorine atoms that are potent atmospheric oxidants but are neglected in models used to assess regional air quality because of lack of measurements. The proposal will measure the fundamental rate constants of real-world playa dust particles with nitrogen oxides to enable robust assessments of regional air quality impacts in salt playas regions such as Texas.
Reactive chlorine (Cl) atoms when activated can serve as potent atmospheric oxidants that would effect lifetimes of greenhouse gases like methane and also tropospheric ozone abundance. The proposal hypothesizes that wind blown chloride-containing dust from dried saline lake beds (playas) can be converted to nitryl-chloride (ClNO2) by heterogeneous reactions with gaseous dinitrogen pentoxide (N2O5). The ClNO2 photolysis produces Cl atoms that could alter the ozone production photochemistry and the methane lifetime significantly. The research will measure the kinetics of ClNO2 production from reactions of salt with N2O5 in a trace gas-aerosol flow reactor. Chemical ionization mass spectrometry will be used to monitor ClNO2 in the reactor and the playa dusts will be analyzed using single-particle mass spectrometry, ion chromatography and X ray diffraction. The in depth analysis of the chemical and atmospheric conditions under which chlorine can be released from the saline playas will provide a mechanistic framework that could be implemented in chemistry-climate and air-quality models to make more robust predictions and assessments.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The goal of this project was to test our hypothesis that chemical reactions between pollutant gases and salty dust particles emitted from dry desert lake beds, called playas by geographers and geologists, can lead to the generation of small quantities of chlorine-containing gases in the air that could worsen air quality by helping to produce ozone, an air pollutant regulated under the Clean Air Act. We collected samples of sediment from playas in the drylands of the Western USA and provided them to our collaborating investigator in Florida to carry out the tests in her laboratory. In order to perform the laboratory tests, some of the playa sediment had to be turned to dust, so together with our collaborators, we designed and built a new type of “dust generator” machine that mimics a turbulent desert windstorm blasting sediment into dust.
The laboratory studies using our dust generator and other equipment confirmed that the playa dusts indeed do lead to the generation of chlorine-containing gases in the air. We discovered that the results depend to some extent on the chemical composition (the kinds of minerals, such as some types of clay) of the playa sediment. In addition to the development of a dust-generating machine of a design that can be copied and built by other researchers for other types of research on dust particles, the results of this project may be used to improve air quality models to forecast air pollution, especially ozone. This may be crucial for human health and compliance with air quality regulations in cities downwind of playas, such as Salt Lake City (which is next to the playa of Great Salt Lake).
Participating in this collaborative research also helped the training and professional education of members of a new generation of scientists, including a post-doctoral researcher, PhD students, and a Master’s student. In addition to describing our findings to the scientific community through papers published in technical journals, the principal investigator also briefed weather forecasters and environmental managers in dusty Western states of the new effects of airborne dust documented by this research.
Last Modified: 07/16/2021
Modified by: Thomas E Gill
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