| NSF Org: |
AGS Division of Atmospheric and Geospace Sciences |
| Recipient: |
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| Initial Amendment Date: | June 29, 2017 |
| Latest Amendment Date: | October 29, 2018 |
| Award Number: | 1700722 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Sylvia Edgerton
sedgerto@nsf.gov (703)292-8522 AGS Division of Atmospheric and Geospace Sciences GEO Directorate for Geosciences |
| Start Date: | July 1, 2017 |
| End Date: | June 30, 2021 (Estimated) |
| Total Intended Award Amount: | $342,299.00 |
| Total Awarded Amount to Date: | $374,322.00 |
| Funds Obligated to Date: |
FY 2019 = $32,023.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1000 OLD MAIN HL LOGAN UT US 84322-1000 (435)797-1226 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Utah State University Vernal UT US 84078-8330 |
| 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: |
01001920DB 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
Atmospheric mercury (Hg) occurs in many forms some of which are more toxic than others. The largest component of Hg, gaseous elemental mercury (GEM) is relatively inert but it oxidizes to gaseous oxidized mercury (GOM) or converts to particle bound mercury (PBM) that are reactive and toxic. Therefore, it is critical to monitor these distinct forms of mercury accurately. The investigators' past work sponsored by NSF has shown that the commercial Tekran systems, which are used widely to monitor reactive mercury and accepted as the standard, are prone to large errors and systematic biases. Specifically, Tekran based reactive GOM and RGM show a persistent low bias and call into question our current understanding of mercury toxicity and exposure. The project will deploy a new suite of instruments globally to provide robust and well-calibrated measurements of reactive mercury globally to improve our predictive knowledge of mercury and its health risks for humans.
The project will develop and deploy a suite of new stable and sensitive instruments for calibrated speciated reactive mercury measurements at a network field sites where conventional Tekran systems have been operating. It builds on preliminary promising results that were supported by NSF. The instruments include a new active GOM system developed by the team that collects GOM on cation exchange and nylon membranes and then analyzes them for reactive mercury. The two-distinct collection and analysis methods will confirm the absence of potential biases from speciation or atmospheric sampling conditions (e.g. high humidity or ozone). This method has been shown to be highly selective with no interference from GEM that is present in much larger amounts. Furthermore, the investigators will deploy an automated GOP and GEM calibrator for routine field verification. Finally, a gas chromatography/mass spectrometry system to separate and identify various oxidized mercury compounds will be co-deployed at multiple sites. The 10 core sites will span the globe and cover a wide range of atmospheric conditions and emission cases. The harmonized bias-free chemically rich global mercury data on mercury will be analyzed to lay a solid observational foundation for the mercury modeling and assessment research community. The systems developed here will be commercialized and made available to the wider community for reliable speciated mercury measurements.
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 objective of this project was to improve methods for measuring oxidized mercury compounds in the ambient atmosphere. Mercury is a ubiquitous environmental pollutant that negatively impacts human and environmental health. It is of most concern in aquatic environments, where it can accumulate up the food chain. However, most sources of mercury pollution emit into the atmosphere, rather than directly into waterways. In the atmosphere, mercury can be transported across the globe before depositing to the earth and impacting the environment. The transport and chemistry of mercury within the atmosphere, and not just the location of sources, thus determine where emitted mercury has an impact.
Atmospheric mercury exists in either the elemental or oxidized form. Elemental mercury is relatively inert, but it can undergo chemical reactions that convert it into oxidized mercury. Oxidized mercury is soluble, reactive, and readily deposits to ecosystems, making it an important part of the atmospheric mercury cycle. In spite of its importance, oxidized mercury exists at very low levels. It is measured in parts-per-quadrillion, meaning that there are only a few molecules of oxidized mercury per quadrillion molecules of everything else in the atmosphere.
Because of its reactivity and low concentrations, accurate measurements of atmospheric oxidized mercury have proven difficult. Many past measurements of oxidized mercury have now been shown to be inaccurate. In this project, we have continued work to develop new methods to measure oxidized mercury, and we have used those methods to better understand the chemistry and distribution of mercury in the atmosphere. We developed and improved two different measurement systems. One is a low-cost system that collects weekly or semi-weekly integrated samples, and the other is a higher-cost system that allows for hourly measurements. We also improved a system to calibrate oxidized mercury measurements. The calibration system adds a known amount of elemental and/or oxidized mercury to an analyzer to make sure the analyzer recovers the same amount that was injected. This ensures that mercury measurements are accurate and trustworthy.
Our work on these measurement and calibration systems is allowing our team and other scientists and governments around the world to better understand how mercury pollution affects human and environmental health.
Last Modified: 09/23/2021
Modified by: Seth Lyman
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