| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | August 24, 2016 |
| Latest Amendment Date: | August 24, 2016 |
| Award Number: | 1649664 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Cynthia Suchman
csuchman@nsf.gov (703)292-2092 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | September 1, 2016 |
| End Date: | June 30, 2019 (Estimated) |
| Total Intended Award Amount: | $114,794.00 |
| Total Awarded Amount to Date: | $114,794.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
160 ALDRICH HALL IRVINE CA US 92697-0001 (949)824-7295 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Croul Hall Irvine CA US 92697-3100 |
| 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): | ANS-Arctic Natural Sciences |
| Primary Program Source: |
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| 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): | 47.078 |
ABSTRACT
Since the Pleistocene, slow organic matter decomposition has led to the accumulation of vast amounts of organic carbon in permafrost. However, while ongoing climate warming and permafrost thaw are expected to increase plant productivity (CO2 uptake), continued warming is also expected to weaken prior constraints on decomposition (CO2 emissions). The net effect of these changes on the Arctic?s carbon budget and the global climate system are poorly understood, as most observations have been made during the short growing season, when root and rhizosphere respiration dominate CO2 emissions. This project will focus on the development of a new technology for the continuous collection of CO2 emitted from arctic tundra soils. This passive diffusive sieve (zeolite) trap for measuring soil respired CO2 will be rugged, small, lightweight, low-cost, and require little in the way of power (batteries) low power. It has the potential to transform our understanding of carbon cycling in the Arctic, as it allows for the year-round CO2 collection, including during the winter and shoulder seasons when sites are often inaccessible, and over multiple weeks (3 weeks/sample), thus integrating both diffusive and episodic emissions. Outreach activities will strengthen the existing NSF-supported K-12 training programs at UC Irvine that are aimed to increase the participation of underprivileged populations in the STEM fields. THE Investigators will engage middle school students with lab tours and activities during a ?Day at College?-experience and class room visits. The project will also train a graduate student, and contribute to educating researchers (via an international summer course) in the use of 14C analysis in Ecology and Earth System Science.
The investigators will develop and deploy a novel system to continuously trap CO2 emitted from arctic tundra soils over several weeks for radiocarbon (14C) analysis. However, typical canister-based systems for measuring soil respired CO2, can be relatively large, expensive to ship, and require line power. This project will develop and deploy a novel system to continuously trap CO2 emitted from Arctic tundra soils over several weeks for radiocarbon (14C) analysis. This continuous collection system has the potential to transform carbon cycle research. Such devices would obviate the need for shipping large canisters to the Arctic as well and the need for line power. Moreover, such devices are relatively inexpensive and lightweight, and therefore, permit for high spatial resolution monitoring. These new traps, however, have never been tested in the Arctic, where the environmental conditions can be harsh, especially in winter. Thus the focus of this work is to develop, harden, and test such devices through a number of winter seasons at the Toolik Lake Long Term Ecological Station, on the north slope of Alaska. If successful, this device will provide the first year-round, quasi-continuous dataset on soil-respired 14CO2 in moist acidic tussock tundra, which is the dominant tundra type of arctic Alaska and globally accounts for over 20% of the tundra land surface. Moreover, this research will point the way for other experimental groups working in similar harsh environments throughout the Arctic.
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.
This project designed, built, and deployed a new type of sampling system that can be used to collect carbon dioxide gas from permafrost soils for subsequent analysis of its radiocarbon content. Specifically, this project aimed to provide new technology to monitor carbon emissions from permafrost soils and new insights to microbial processes in snow-covered soils.
Arctic soils contain 30-50% of all organic carbon stored in soils on Earth. Most of this carbon (in form of organic matter) is currently frozen and has been preserved in permafrost for millennia. Scientists have been documenting rapid warming of the Arctic and are concerned that permafrost thaw may expose this carbon to microorganism which could convert it into the greenhouse gases carbon dioxide or methane. In addition, scientists have recently discovered that microorganisms remain active at much lower temperatures than expected and that Arctic tundra ecosystems emit carbon dioxide during the winter. We know very little about the carbon sources that fuel microbial activity during the this cold and dark period.
Radiocarbon is a radioactive isotope that is produced in the atmosphere by the interaction of cosmic ray with nitrogen gas and can also be produced by thermo-nuclear technology. It is oxidized to carbon dioxide and enters the food chain via photosynthesis. Soils emit carbon dioxide because roots and microorganisms respire it, and these two sources can be distinguished via their radiocarbon contents (new vs. old carbon). In addition, permafrost carbon has a lower radiocarbon content than other soil carbon (very old carbon). Plants sequester carbon dioxide that is rich in radiocarbon (new carbon) from the atmosphere during photosynthesis to build biomass, but also respire some of this carbon dioxide. Microorganisms consume organic matter that has been stored in soils for many years (and therefore lost radiocarbon due to radioactive decay (old carbon)) and subsequentially respire this carbon as carbon dioxide. Permafrost has preserved organic matter from microbes for millennia, but not from decay – permafrost carbon has a low radiocarbon content (very old carbon).
This project collected carbon dioxide and monitored carbon dioxide concentrations, soil temperature and moisture at one permafrost soil location at four depths over a period of two years. An analysis of existing, long-term soil temperature and thaw depth data sets revealed that this site had not undergone significant permafrost thaw. The project data showed that portions of the soil remained thawed from May through January, with frost onset in October and complete freeze-up in early January. The project found that carbon dioxide emissions during the summer were dominated by new carbon. During the winter, older carbon dioxide was observed at all depth, and the oldest in later winter – indicating that new carbon is an important resource for microorganisms during the early winter. Consequently, this project provides evidence that rapid warming and the extension of the frost-free period has the potential to result in a depletion of carbon stocks and a positive feedback to climate change.
This project was a collaboration between three research groups from the University of California (Irvine) and Alaska (Anchorage & Fairbanks). It trained two graduate (Ph.D.) students and two undergraduate (B.S.) students in field and, or laboratory methods, data analysis, and scientific writing, and partially supported several research scientists and technicians.
To promote geoscience education, team members supported K-8 (science) educators with class-room visits, Earth (Science) Day events, and tours of the university laboratories. The team also provided learning opportunities for researchers by organizing two international summer courses that trained undergraduate, graduate students, researchers, and technicians in the use of isotopes in earth science, ecology, and environmental forensics.
The study was conducted at Toolik Field Station in the Arctic tundra of Alaska. In addition to providing lodging and access to electricity and the internet in this remote location, the station’s research staff was critical to the success of this project. Station staff changed gas sampling units, conducted equipment maintenance, worked with the project team to improve the design of the samplers, and provided observations of weather and ground conditions.
Last Modified: 09/09/2019
Modified by: Claudia I Czimczik
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