Research Foci
Our overarching goal is to:
- Integrate feedbacks between the three major processes governing the critical zone -- the water cycle, the mineral cycle, and the carbon cycle ...
- within contrasting land uses...
- as materials are transported and transformed across geophysical boundaries that traditionally separate scientific disciplines (i.e. sapprolite → topsoils → aquifers → riparian floodplains → wetlands → river networks → salt marshes → estuaries → sea).
Our overall hypotheses are that:
- Processes that mix minerals and carbon are rate limiting to watershed-scale carbon sequestration, chemical weathering and soil production.
- Humans accelerate rates of carbon-mineral mixing, resulting in anthropogenic carbon sequestration significant to local, regional and global budgets.
Our multi-disciplinary objectives
are described below.
Conceptual model illustrating our hypothesis that processes that mix minerals and carbon are rate limiting to watershed-scale chemical weathering, soil production & carbon sequestration. Credit: Aufdenkampe & Yoo.
1. Properties of Carbon-Mineral Complexes
Contact: Anthony Aufdenkampe
We are conducting a suite of experiments and field observations to test two hypotheses:
- The capacity of the inorganic matrix to complex and stabilize OC is a multivariate function of mineral surface area, mineralogy, polyvalent cations and OM composition. i.e. %OC = f(surface area, mineral, cations, OM composition, etc.)
- The intrinsic biological and chemical stability of organic carbon complexed by an inorganic matrix can be predicted from the OM composition and its concentration relative to complexation potential
2. Weathering and Erosion Controls on Carbon-Mineral Complex Formation
Contact: Kyungsoo Yoo
We are conducting a suite of field observations to test 3 hypotheses:
- Organo-mineral complexation in natural uplands is limited by physical mineral supply from the underlying B horizon or saprolite, which are governed by vertical soil mixing (<10 yr time scale) and landscape lowering (>10 Kyr time scale).
- Coupled chemical and microbial weathering processes determine the spatial distribution of the sources of OC-complexation potential
- Human accelerated erosion and chemical weathering significantly increase the production of OC-complexation potential
3. Fluvial Network Controls on Carbon-Mineral Complex Formation & Preservation
Contact: Jim Pizzuto
We are conducting a suite of field observations to test 2 hypotheses:
Accelerated erosion by modern agricultural and construction activities (1) creates fluvial carbon sinks within the watersheds and (2) decreases overall bioavailability of the stream water carbon leaving the watershed
Tasks include:
- Tracer Characterization of Sediment Sources
- Determine Modern Sedimentation Rates and Concentrations
- Determine Historical Rates and Concentrations
4. Watershed Integration of Erosion-Driven Carbon Sequestration
Contact: Anthony Aufdenkampe, J. Denis Newbold
Whole watershed calculations of carbon complexation rate. Requires:
- hillslope to colluvium erosion flux data (Obj 2)
- alluvial sedimentation (Obj. 3)
- erosion sources and %OC values (Obj. 2&3)
Whole watershed calculation of carbon sequestration rate. Requires:
- Stream metabolism (P/R) measurements
- Erosion-induced destabilization of soil aggregates
Whole watershed estimates of sediment fluxes, source water contributions, riparian zone dynamics.
- Implementation of PIHM watershed model.
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