| NSF Org: |
DEB Division Of Environmental Biology |
| Recipient: |
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| Initial Amendment Date: | June 20, 2018 |
| Latest Amendment Date: | June 20, 2018 |
| Award Number: | 1753731 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Matthew Kane
mkane@nsf.gov (703)292-7186 DEB Division Of Environmental Biology BIO Directorate for Biological Sciences |
| Start Date: | July 1, 2018 |
| End Date: | June 30, 2023 (Estimated) |
| Total Intended Award Amount: | $606,156.00 |
| Total Awarded Amount to Date: | $606,156.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1109 GEDDES AVE STE 3300 ANN ARBOR MI US 48109-1015 (734)763-6438 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
830 N. University Ave Ann Arbor MI US 48109-1048 |
| 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): |
ECOSYSTEM STUDIES, ANS-Arctic Natural Sciences |
| Primary Program Source: |
0100XXXXDB 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): | 47.074 |
ABSTRACT
About half of the carbon that moves from land to streams, rivers, and lakes is lost to the atmosphere as carbon dioxide. Carbon from land is converted to CO2 mainly by microbial respiration and exposure to sunlight. Both processes happen in sunlit surface waters, but little is known about how they interact to produce CO2. For instance, previous research has shown that sunlight exposure can either increase or decrease microbial respiration. In addition, there is little known about how composition of microbial communities may influence microbial respiration. Understanding how microbes and sunlight interact is particularly important in the Arctic where thawing permafrost soils will release large amounts of carbon from land to water. Advancing our understanding of loss of this carbon to the atmosphere is critical to understanding the global carbon cycle. This project takes advantage of recent advances in microbial genomics and carbon chemistry to improve understanding of carbon cycling in Arctic freshwaters. This research will also engage high school teachers and students in scientific discovery and application. The PIs also plan to provide undergraduates with research opportunities through this project.
Determining the controls on coupled photo-bio conversion of dissolved organic carbon (DOC) to CO2 is essential for understanding the drivers of CO2 fluxes to the atmosphere from inland waters in the Arctic. To gain this understanding, this project will use experiments to answer three questions: (Q1) How is microbial metabolism controlled by DOC chemistry? This question will be answered with incubations of microbial communities with DOC leached from surface soils and deeper permafrost soils from two dominant arctic landscapes. Microbial pathways of DOC conversion to CO2 will be identified by measuring microbial gene abundance and the expression of those genes, and molecular formulas of DOC that are consumed and produced during incubations identified by mass spectrometry; (Q2) How does DOC exposure to sunlight alter how microbes convert DOC to CO2? This question will be answered by exposing leached soil DOC to sunlight; (Q3) How does the longer-term adaptation of microbial communities affect the rate of DOC conversion to CO2? This question will be answered by measuring microbial abundance, respiration, production, and community composition (species) during the incubations. A detailed understanding of these processes is critical because conversion of permafrost soil carbon to CO2 has the potential to create a positive and accelerating feedback to atmospheric CO2 levels and resulting environmental changes.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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.
NSF - DEB 1753731. Collaborative research: Coupled biological and photochemical degradation of dissolved organic carbon in the Arctic
Rose M. Cory, University of Michigan
George W. Kling, University of Michigan
Byron C. Crump, Oregon State University
Scientific Merit. This research supported by the National Science Foundation (NSF) investigated how organic carbon in frozen soils of the far north (permafrost soils) is converted to the greenhouse gas carbon dioxide (CO2). These frozen soils are found in the Arctic and are beginning to thaw due to global climate warming. Once thawed, the organic carbon (mostly dead plant material) in the soils can be degraded by bacteria or by sunlight to form carbon dioxide. Some of these soils have been frozen for many thousands of years, and the critical scientific question is whether the carbon in these ancient soils is still vulnerable to degradation, or whether it will remain unchanged in the soil. The main reason this scientific question is important is because these frozen soils contain huge amounts of carbon, twice as much as is now in the atmosphere, and if the carbon they store is thawed and released to the atmosphere as a greenhouse gas, then the current rate of global warming will be amplified.
In this research we produced results and knowledge showing several things. First, we found that this newly-thawed carbon is vulnerable to bacterial degradation to carbon dioxide, even if the ancient carbon was up to 8,000 years old. Second, we found that when this thawed carbon was exposed to sunlight at Earth?s surface, the sunlight itself could degrade the newer and also the ancient carbon to produce carbon dioxide. In addition, we found that there was an interaction between the sunlight and the bacteria that worked as follows ? when the soil carbon was exposed to sunlight, it altered the carbon and allowed the bacteria to degrade more of it than they could when the carbon was in the dark. That is, exposing the carbon in these frozen soils to sunlight stimulated the bacteria to produce even more carbon dioxide. Third, we discovered that chemical reactions in soils can degrade organic carbon to carbon dioxide, without the help of bacteria or sunlight. This chemical degradation of soil carbon is substantial, and should be considered in our understanding of how carbon is degraded in soils and in our predictions of the amounts of soil carbon degraded to carbon dioxide in the near-term future. Finally, we found that newly-thawed soils supported the species of bacteria that use iron to gain energy and grow, which degrades organic carbon to carbon dioxide in the process. These iron-using bacteria may thus stimulate the production of carbon dioxide in previously frozen soils that are rich in iron, and these iron-rich soils are found in many areas of the Arctic.
Broader Impacts. The main driver of climate change and global warming is the human input of heat-trapping gases (greenhouse gases) into the atmosphere, and this input is currently about 9 billion tons of carbon per year (released as carbon dioxide). This human input has disrupted the natural behavior of carbon on Earth to the point that we are quickly warming our planet, which threatens food production, business and economics, coastlines and infrastructure, and the overall well-being of humans. This NSF research has helped scientists to constrain our understanding of the potential strength of how the Arctic will amplify global warming in this century. In turn, this new knowledge will help managers and decision makers in society to better prepare for, reduce, or adapt to the impacts of climate change we will continue to face. Finally, this research project contributed to teaching and outreach through the NSF PolarTREC program for high school teachers, the NSF Research Experience for Undergraduates, and the training of graduate students as well as presentations and articles in the popular press.
Last Modified: 07/02/2023
Modified by: George W Kling
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