| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
|
| Initial Amendment Date: | July 13, 2017 |
| Latest Amendment Date: | June 17, 2019 |
| Award Number: | 1642402 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Laura Lautz
llautz@nsf.gov (703)292-7775 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 15, 2017 |
| End Date: | June 30, 2022 (Estimated) |
| Total Intended Award Amount: | $308,587.00 |
| Total Awarded Amount to Date: | $308,587.00 |
| Funds Obligated to Date: |
FY 2018 = $149,794.00 FY 2019 = $55,885.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
5100 Marine Street, Room 481 Boulder CO US 80303-1058 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Hydrologic Sciences |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT 01001920DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
There is considerable exchange of water and solutes among four compartments of streams: the fast moving part of the stream channel, in-channel storage zones, and shallow and deep sediments zones. Exchanges of water between these compartments promote dissolved nutrient reactions and removal. The team hypothesizes that nutrient reaction in streams is controlled by not only hydrologic transport, but also stoichiometry of nutrients (ratio of C:N:P). The team will test their hypotheses by conducting field data collection and stream solute injections at three contrasting Critical Zone Observatory (CZO) sites (Boulder Creek, a rocky mountain setting in Colorado; Catalina-Jemez, a low nutrient setting in New Mexico; and an agricultural landscape in Iowa). Across these three sites there is substantial variability in geology, hydrology, and background nutrient concentrations (and therefore nutrient limitations). The project will engage multiple graduate students with an emphasis on diversity. The team will also organize a workshop to promote and stimulate interaction and exchange of ideas and knowledge among the principal players in the stream restoration field, particularly young scientists and practitioners, stream restoration companies and local environmental agencies.
The exchange of water and solutes among the river and its hyporheic zones result in a net reaction and removal on nutrients from the stream. Nutrient reaction and removal (carbon, nitrogen, and phosphorous) in streams is limited by not only the biomass available to take up nutrients, but is also stoichiometrically limited by the specific reaction. This project will work with the hypothesis that: (1) nutrient retention in streams is controlled by not only hydrologic transport, but also stoichiometry of nutrients (ratio of C:N:P); (2) each compartment of a stream (main channel, surface storage, shallow/deep hyporheic) has a different optimal stoichiometric need (i.e., C:N:P); and (3) depletion of dissolved oxygen from aerobic metabolism is a first-order control that causes a threshold change in the stoichiometric demand of C, N, and P as a compartment becomes anoxic and biogeochemical processes change. The concepts will be tested by conducting field data collection and stream solute injections at three contrasting Critical Zone Observatory (CZO) sites across variable hydrologic conditions at each site to test over a range of hydrologic transport conditions. The team will deploy a suite of methods including electrical resistivity imaging, nutrient tracer injections based on stoichiometric tradeoffs, the Tracer Additions for Spiraling Curve Characterization (TASCC method), application of the "smart" tracer resazurin in streams and use of shallow (MINIPOINT samplers) and deep (wells) hyporheic flow paths. Nutrient tracer injections are designed to specifically decipher stoichiometric controls on nutrient retention in each of the four compartments of the streams. The broader impacts will be communicated in a workshop setting that identifies reciprocal needs from academic research and restoration programs seeking to approach stream restoration projects more holistically.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
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.
In this research project we focused on the controls on transport of dissolved nutrients in streams (ie., nitrogen and phosphorous). It is well established that stream water moves in several ways down stream channels - advection (bulk flow of water), dispersion (some moves ahead and lags a little behind the bulk flow), and exchange (water that moves into and out of storage zones like eddies, pools, and the streambed). Downstream transport of dissolved nutrients should be controled by physical processes and biological processes. With respect to the latter, we expected that the ratio of nitrogen to phosphorous was an important aspect that had not yet been evaluated in the physical storage zones of streams such as pools, eddies, and in the streambed. Whereas the physical processes move streamwater and nutrients into these storage zones, it is biological processes that cause changes in nutrient concentrations. At increasing streamflows, we found that there was an appreciable amount of stream water exchanging with surface storage zones. A reliable measurement of biological processes is respiration rate. We estimated respiration in storage zones and related nutrient uptake in these zones under different mixtures of nitrogen and phosphorous and could not find a clear relatioinship between the two, nor a relationship between nutrient uptake and discharge, suggesting that there is not a clear nutrient limitation to the biological processes in these zones. This is surprising because at the scale of stream reaches, it has been common to find nutrient retention more strongly related to the mix of nutrients avaialble. We also pioneered new methods for visualizing the movement of stream water into the subsurface using geophysical techniques. The new method focuses on proceeing the collected field data with little to no decisions required by researchers. Thus it is more objective. Our project was hindered by the pandemic in that we had originally planned to hold workshops to teach students about our field methods. Pivoting during the pandemic, we instead generated 3 videos about stream tracer injection techniques and translated them into Spanish and Mandarin. They are freely available online from a youtube channel hosted by the Consortium of Universities for the Advancement of Hydrolgic Sciences Inc. (CUAHSI).
Last Modified: 04/28/2023
Modified by: Michael N Gooseff
Please report errors in award information by writing to: awardsearch@nsf.gov.
