| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | June 30, 2017 |
| Latest Amendment Date: | February 8, 2019 |
| Award Number: | 1656988 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Enriqueta Barrera
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | September 1, 2017 |
| End Date: | August 31, 2019 (Estimated) |
| Total Intended Award Amount: | $124,237.00 |
| Total Awarded Amount to Date: | $149,061.00 |
| Funds Obligated to Date: |
FY 2019 = $24,824.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
501 E HIGH ST OXFORD OH US 45056-1846 (513)529-3600 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
OH US 45056-1846 |
| 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): | Geobiology & Low-Temp Geochem |
| Primary Program Source: |
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
Soils contain abundant organic carbon, mostly in intimate association with fine-grained phyllosilicate minerals (interchangeably called clay minerals). Mineral-associated organic carbon is believed to be stable against microbial respiration because of various protection mechanisms, which ultimately decrease the amount of greenhouse gas emission. However, current biogeochemical models that predict greenhouse effect do not adequately consider the complexity of this carbon stock, and model prediction is often at odds with experimental evidence. This model-experiment inconsistency calls for need for an improved understanding of how and to what extent mineral-associated organic carbon is available to microbial decomposition. The ultimate goal of this project is to study the role of clay minerals in mediating microbial decomposition of soil organic matter in response to warming temperature. Various soil organic matter-clay mineral interaction experiments will be performed under well-controlled conditions across a range of temperatures. Experimental data will be used to derive parameters that can be incorporated into biogeochemical models to better predict microbial decomposition of soil organic matter in response to temperature. Reliable predictions of soil carbon turnover are essential to enhanced food security, reduced soil degradation, and mitigation of biodiversity loss. An improved model prediction of future greenhouse emission and environmental change will better enable our society to develop sustainable agriculture and to deal with recently frequent extreme weather and natural disasters.
The goal of this proposal is to assess the role of phyllosilicates in mediating the temperature sensitivity of soil organic matter decomposition. The hypothesis posits that soil phyllosilicate minerals control substrate bioavailability and enzyme activity, and thus, by extension, the temperature sensitivity of substrate decomposition in soil. To corroborate this view, investigators propose to integrate mechanistic experimental investigation with innovative biogeochemical (BGC) modeling. They will focus on the ubiquitous phyllosilicates because of their importance in soils and existing knowledge gap. In this one-year demonstration project, they will perform laboratory experiments of enzyme-carbon substrate-mineral interaction (adsorption) experiments. Common soil clay minerals will be used. Organic polymers representing the functionalities of proteins, cellulose, and lignin will be selected as substrate proxies and â-glucosidase, leucine aminopeptidase, and phenol oxidase as enzyme indicators. Kinetic adsorption data will be fitted to derive: 1) the adsorption capacity and affinity of different substrates (and enzymes) onto mineral surfaces; and (2) Vmax and affinity parameters for enzyme-substrate interactions. These parameters and their temperature dependence will be used to parameterize the Equilibrium Chemistry Approximation kinetics. An improved BGC model will reduce uncertainty in current predictions of the response of soil organic carbon stocks to ongoing warming temperature. In addition of regular data dissemination through student involvement, publications, and presentations, results will be incorporated into courses. Content-specific video clips will be exhibited in museums. All investigators will make efforts to visit under-represented K-12 schools to deliver general science lectures and lead various science activities.
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.
Soils contain abundant organic carbon, mostly in intimate association with fine-grained phyllosilicate minerals (interchangeably called clay minerals). Mineral-associated organic carbon is believed to be stable against microbial respiration because of various protection mechanisms, which ultimately decrease the amount of greenhouse gas emission. However, current biogeochemical models that predict greenhouse effect do not adequately consider the complexity of this carbon stock, and model prediction is often at odds with experimental evidence. This model-experiment inconsistency calls for need for an improved understanding of how and to what extent mineral-associated organic carbon is available to microbial decomposition.
The goal of this project was to study the role of clay minerals in mediating microbial decomposition of soil organic matter in response to warming temperature. We performed soil organic matter (SOM) - clay mineral interaction experiments under well-controlled conditions under. Our results show that mineral-associated soil organic matter (humic substances, lignin etc.) can undergo biotic transformation via their role as electron donor and electron shuttle to couple with reduction of solid-phase Fe(III) in mineral structures. Transformation products are more labile compounds with increased bioavailability. When enzyme and substrate are attached to mineral surface, their interaction efficiency (i.e., substrate degradation by enzymes) decreases relative to free enzymes and substrates (i.e., un-attached ones). Some attached enzymes undergo and proteins undergo biotic and abiotic fragmentation. SOM affect mineral transformations. These results collectively suggest that mineral associated SOM is not necessarily stable, and when coupled with redox processes of soil minerals, SOM can actually undergo certain extent of transformation.
Last Modified: 01/01/2020
Modified by: Hailiang Dong
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