| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | December 14, 2016 |
| Latest Amendment Date: | December 20, 2017 |
| Award Number: | 1624618 |
| Award Instrument: | Fellowship Award |
| Program Manager: |
Sylvia Edgerton
sedgerto@nsf.gov (703)292-8522 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | December 1, 2016 |
| End Date: | November 30, 2018 (Estimated) |
| Total Intended Award Amount: | $86,000.00 |
| Total Awarded Amount to Date: | $172,000.00 |
| Funds Obligated to Date: |
FY 2018 = $86,000.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
Lafayette IN US 47905-1702 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Providence RI US 02912-9019 |
| 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): | Postdoctoral Fellowships |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Ammonia emissions that produce and neutralize aerosols are increasing in the US . While the agricultural ammonia sources from fertilizer use dominate and are well studied, field studies show that ammonia produced from fossil fuel use in urban areas is underrepresented in current models. This may be a result of the use of various catalytic NOx scrubber technologies in vehicles and power-plants to reduce air pollution that can increase ammonia production, particularly in urban areas. The proposal will use isotope specific ammonia measurements to quantify the fossil fuel related sources in Rhode Island, Indianapolis and Philadelphia. The results will help determine how fossil energy use and and pollution abatement technologies are affecting urban ammonia sources and human health.
The research will use isotopic (15N/14N) studies to develop fingerprinting tools for fossil ammonia sources from automobile engines, power plants, and catalytic NOx scrubbers, agricultural and oceanic sources. Field studies in Providence, Indianapolis, and Rhode Island will be performed to quantitatively attribute the ammonia sources using the 15N/14N observations of ammonia. State of the art instrumentation will be used for the measurements and the results will resolve the outstanding debate on how much fossil combustion is contributing to the ammonia budget and how catalytic NOx scrubber technologies are affecting them.
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.
Ammonia (NH3) is a critical component of our atmosphere that has important implications for both human health and climate. The vast majority of NH3 is released into the atmosphere from agricultural-related activities. However, observations in urban regions, in which agricultural activities are limited, have indicated significantly higher levels of NH3 than can be explained from models. This mismatch suggests there might be an underestimation of an important urban NH3 emission source. Elevated urban NH3 may possibly be related to the recent emergence of fossil-fuel combustion derived emissions in which technology aimed to reduce nitrogen oxides (NOx) emissions have resulted in an undesirable consequence of releasing NH3. The relative importance of fossil-fuel combustion derived NH3 however, remains unclear. Nitrogen stable isotope composition analysis has been suggested as a novel tool that can allow for a further understanding of NH3 emissions sources as different sources tend to have distinctive values (or "fingerprints"). However, NH3 is very difficult to accurately sample due to its reactivity, and no method has been verified for its suitability for accurate isotopic characterization.
In this project, I have developed and rigorously tested a sampling device for NH3 and its reaction product, ammonium (p-NH4+), for concentration and isotopic characterization. This method collects NH3 on an acid-coated honeycomb glass apparatus and collects p-NH4+ on a particulate filter pack. Utilizing this new collection technique, traffic-derived NH3 emissions were evaluated in stationary near-highway and mobile-highway measurements. It is found that traffic is a significant source of NH3 that is strongly related to carbon monoxide (CO), an indicator of fossil-fuel combustion. Based on these measurements, it is suggested that traffic-derived NH3 tends to be underestimated by a factor of 4.5 in our national emission inventory estimates. This suggests that vehicle emissions could be an important under constrained emission source in urban regions. It is also found that NH3 plays a key role in particulate matter formation near highways that has important implications for human health. Isotopic measurements of traffic-derived NH3 indicates a distinct value (or "fingerprint") enabling the potential to track its emissions in urban regions.
The role of traffic-derived emissions on urban regions was then investigated by monitoring the concentrations and isotopic compositions of NH3(g) and p-NH4+ (together referred to as NHx) at an urban location (Providence, RI) over the course of one-year. Chemical composition analysis of particulate matter indicates that NH4+ represents the largest component of inorganic fine particle matter throughout the year. Additionally, it is found that NHx concentrations are strongly connected with temperature, indicating the presence of a temperature-dependent emission source. Isotopic analysis indicates that the elevated NHx concentrations found during the summer may be related to either electricity generation via natural gas-powerplants or NH3 released from the ground during warm temperatures. During the winter, NHx tends to have a similar isotopic composition as traffic-derived NHx, indicating the importance of vehicles as an urban source during this season. Overall, this project has significantly contributed to our understanding of NHx in urban regions and the method development component of this project will enable further constraints in subsequent studies.
Last Modified: 12/06/2018
Modified by: Wendell W Walters
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