Date of Award

Spring 1-1-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Michael N. Gooseff

Second Advisor

Diane M. McKnight

Third Advisor

Ben Livneh

Abstract

The open-channel oxygen method quantifies rates of gross primary productivity (GPP) and ecosystem respiration (ER) by employing the diel dissolved oxygen (DO) curve. This attributes stream metabolism to four processes: photosynthesis, oxidative respiration, reaeration, and groundwater flux. Groundwater flux, however, is often assumed to be negligible, which may introduce bias in estimates of metabolism. To investigate this, whole-stream metabolism and groundwater flux were measured in Como Creek, Colorado during the summer of 2018. Results from the BASE (Bayesian Single-station Estimation) metabolism model indicate that periods of anoxic groundwater input result in an overestimation of ER in baseline simulations. These data suggest that the assumption that groundwater flux is negligible in the open-channel oxygen method is inadequate for modeling whole-stream metabolism in highly-aerated alpine streams. However, results are highly susceptible to constraints initiated for reaeration and primary productivity, as well as the methodology for computing net groundwater flux.

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