Date of Graduation

8-2016

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MS)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor

G. Scott Osborn

Committee Member

J. Thad Scott

Second Committee Member

Benjamin R. Runkle

Keywords

Applied sciences; Health and environmental sciences; Earth sciences; Benthic respiration; Diffusion; Lakes; Sediment oxygen demand

Abstract

A steady-state mass diffusion model used with simple measurable and calculable inputs for determining sediment oxygen demand (SOD) is compared to an intact core incubation (ICI) SOD method using samples from three lakes. The mass diffusion model coupled with inputs is known as the measure-calculate method (M-C) and is a potential alternative to existing methods for measuring SOD which are more complex, time-consuming, and costly. The M-C method requires inputs for volumetric sediment oxygen uptake (Ṅsed), sediment density and porosity, and water properties. Ṅsed was determined by suspending sediment in oxygen-saturated water with a DO probe and determining the steady state rate of oxygen decline for the volume of sediment suspended. The SOD values determined using the M-C method were not significantly different from SOD determined using the ICI method using water property inputs representative of lake conditions. Thus, the study confirms the method’s efficacy under test conditions and encourages further research. A separate comparison using water property inputs representative of conditions within incubated cores showed that M-C SOD correlated negatively against ICI SOD despite having similar mean values. This appears to be a result of different boundary conditions for flow velocity and DO within the core, and may discourage the ICI method’s use, as tested, for determining actual in-situ lake SOD.

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