Improved modeling of sediment oxygen kinetics and fluxes in lakes and reservoirs

Xiamei Man, Kevin Bierlein, Chengwang Lei, Lee Bryant, Alfred Wuest, John C. Little

Research output: Contribution to journalArticle

Abstract

To understand water quality degradation triggered by hypoxia, we need to understand sediment oxygen fluxes, the main oxygen sink in shallow hypolimnia. Kinetic models that integrate diffusion and consumption of dissolved oxygen in freshwater sediments usually assume a downward flux of dissolved oxygen from the sediment-water interface (SWI) with a zero-flux condition at the lower boundary of the oxic sediment layer. In this paper, we separately account for the oxidation of an upward flux of reduced compounds by introducing a negative flux of oxygen as a lower boundary condition. Using in situ measurements in two water bodies, kinetic models were fit to oxygen microprofiles using zero-order and first-order kinetics with both zero and non-zero lower boundary conditions. Based on visual inspection and goodness-of-fit criteria, the negative-flux lower boundary condition, -0.25g O2 m2d-1, was found to more accurately describe oxygen consumption kinetics. Fitted zero-order rate constants ranged from 50 – 510 mg L-1 d-1 and fitted first-order rate constants ranged from 60 – 400 d-1, which agree well with prior laboratory studies. Sediment-side oxygen fluxes at the SWI calculated from the simulated profiles with the negative-flux lower boundary condition also showed better agreement with the observed oxygen fluxes than the simulated profiles with the zero-flux lower boundary condition.
Original languageEnglish
JournalEnvironmental Science & Technology
Publication statusAccepted/In press - 2020

Cite this

Man, X., Bierlein, K., Lei, C., Bryant, L., Wuest, A., & Little, J. C. (Accepted/In press). Improved modeling of sediment oxygen kinetics and fluxes in lakes and reservoirs. Environmental Science & Technology.

Improved modeling of sediment oxygen kinetics and fluxes in lakes and reservoirs. / Man, Xiamei; Bierlein, Kevin; Lei, Chengwang; Bryant, Lee; Wuest, Alfred ; Little, John C.

In: Environmental Science & Technology, 2020.

Research output: Contribution to journalArticle

Man, Xiamei ; Bierlein, Kevin ; Lei, Chengwang ; Bryant, Lee ; Wuest, Alfred ; Little, John C. / Improved modeling of sediment oxygen kinetics and fluxes in lakes and reservoirs. In: Environmental Science & Technology. 2020.
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abstract = "To understand water quality degradation triggered by hypoxia, we need to understand sediment oxygen fluxes, the main oxygen sink in shallow hypolimnia. Kinetic models that integrate diffusion and consumption of dissolved oxygen in freshwater sediments usually assume a downward flux of dissolved oxygen from the sediment-water interface (SWI) with a zero-flux condition at the lower boundary of the oxic sediment layer. In this paper, we separately account for the oxidation of an upward flux of reduced compounds by introducing a negative flux of oxygen as a lower boundary condition. Using in situ measurements in two water bodies, kinetic models were fit to oxygen microprofiles using zero-order and first-order kinetics with both zero and non-zero lower boundary conditions. Based on visual inspection and goodness-of-fit criteria, the negative-flux lower boundary condition, -0.25g O2 m2d-1, was found to more accurately describe oxygen consumption kinetics. Fitted zero-order rate constants ranged from 50 – 510 mg L-1 d-1 and fitted first-order rate constants ranged from 60 – 400 d-1, which agree well with prior laboratory studies. Sediment-side oxygen fluxes at the SWI calculated from the simulated profiles with the negative-flux lower boundary condition also showed better agreement with the observed oxygen fluxes than the simulated profiles with the zero-flux lower boundary condition.",
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AU - Wuest, Alfred

AU - Little, John C.

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AB - To understand water quality degradation triggered by hypoxia, we need to understand sediment oxygen fluxes, the main oxygen sink in shallow hypolimnia. Kinetic models that integrate diffusion and consumption of dissolved oxygen in freshwater sediments usually assume a downward flux of dissolved oxygen from the sediment-water interface (SWI) with a zero-flux condition at the lower boundary of the oxic sediment layer. In this paper, we separately account for the oxidation of an upward flux of reduced compounds by introducing a negative flux of oxygen as a lower boundary condition. Using in situ measurements in two water bodies, kinetic models were fit to oxygen microprofiles using zero-order and first-order kinetics with both zero and non-zero lower boundary conditions. Based on visual inspection and goodness-of-fit criteria, the negative-flux lower boundary condition, -0.25g O2 m2d-1, was found to more accurately describe oxygen consumption kinetics. Fitted zero-order rate constants ranged from 50 – 510 mg L-1 d-1 and fitted first-order rate constants ranged from 60 – 400 d-1, which agree well with prior laboratory studies. Sediment-side oxygen fluxes at the SWI calculated from the simulated profiles with the negative-flux lower boundary condition also showed better agreement with the observed oxygen fluxes than the simulated profiles with the zero-flux lower boundary condition.

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