Assessing the Performance of Reaeration Prediction Equations

Palumbo, James E.; Brown, Linfield C.

doi:10.1061/(asce)ee.1943-7870.0000799

Cited by 24 publications

(32 citation statements)

References 17 publications

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“…). The largest discrepancies, by up to a factor of three, were observed at nighttime, while, during the daytime, mean values were within reported uncertainties for this approach (Palumbo and Brown ). Potential issues with NR method applicability or dataset quality were deemed marginal, as both CE and GA met the requirements of the NR method ( see “Methods” section), and the O 2 time series were of a high quality (Supporting Information Fig.…”

Section: Discussionsupporting

confidence: 76%

“… Reference equation numbers and abbreviations from Aristegi et al () and Palumbo and Brown (), respectively.…”

Section: Discussionmentioning

confidence: 99%

“… With k 2 ′ being 31,183 s m −1 d −1 for Q < 0.280 m 3 s −1 and 22,500 s m −1 d −1 for Q > 0.280 m 3 s −1 , respectively (Palumbo and Brown ).…”

Section: Discussionmentioning

confidence: 99%

“… These equations were identified to be the most suited (i.e., top performer) for the site mean depth and flow based on the suggestions of Palumbo and Brown ().…”

Section: Discussionmentioning

confidence: 99%

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Headwater gas exchange quantified from O₂ mass balances at the reach scale

Rovelli

Attard

Heppell

et al. 2018

Limnology & Ocean Methods

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Headwater streams are important in the carbon cycle and there is a need to better parametrize and quantify exchange of carbon‐relevant gases. Thus, we characterized variability in the gas exchange coefficient (k 2) and dissolved oxygen (O2) gas transfer velocity (k) in two lowland headwaters of the River Avon (UK). The traditional one‐station open‐water method was complemented by in situ quantification of riverine sources and sinks of O2 (i.e., groundwater inflow, photosynthesis, and respiration in both the water column and benthic compartment) enabling direct hourly estimates of k 2 at the reach–scale (~ 150 m) without relying on the nighttime regression method. Obtained k 2 values ranged from 0.001 h−1 to 0.600 h−1. Average daytime k 2 were a factor two higher than values at night, likely due to diel changes in water temperature and wind. Temperature contributed up to 46% of the variability in k on an hourly scale, but clustering temperature incrementally strengthened the statistical relationship. Our analysis suggested that k variability is aligned with dominant temperature trends rather than with short‐term changes. Similarly, wind correlation with k increased when clustering wind speeds in increments correspondent with dominant variations (1 m s−1). Time scale is thus an important consideration when resolving physical drivers of gas exchange. Mean estimates of k 600 from recent parametrizations proposed for upscaling, when applied to the settings of this study, were found to be in agreement with our independent O2 budget assessment (within < 10%), adding further support to the validity of upscaling efforts aiming at quantifying large‐scale riverine gas emissions.

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Section: Discussionsupporting

confidence: 76%

“… Reference equation numbers and abbreviations from Aristegi et al () and Palumbo and Brown (), respectively.…”

Section: Discussionmentioning

confidence: 99%

“… With k 2 ′ being 31,183 s m −1 d −1 for Q < 0.280 m 3 s −1 and 22,500 s m −1 d −1 for Q > 0.280 m 3 s −1 , respectively (Palumbo and Brown ).…”

Section: Discussionmentioning

confidence: 99%

“… These equations were identified to be the most suited (i.e., top performer) for the site mean depth and flow based on the suggestions of Palumbo and Brown ().…”

Section: Discussionmentioning

confidence: 99%

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Headwater gas exchange quantified from O₂ mass balances at the reach scale

Rovelli

Attard

Heppell

et al. 2018

Limnology & Ocean Methods

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“…Studies of the controls on oxygen aeration [e.g., Moog and Jirka , ; Palumbo and Brown , ] have shown how a range of hydraulic factors, including velocity, depth, and channel slope, can be used to produce statistical equations, which can be used to calculate the capacity for fluvial systems to absorb gas from the atmosphere. While these studies provide understanding of gas fluxes, there is a range of forms of the predictive relationships and recognition that existing approaches are restricted by the range of flow depths and velocities for which gas transfer data are available and by the quality of the overall database [ Palumbo and Brown , ]. In essence, gas transfer across the air‐water interface occurs by molecular diffusion [ Moog and Jirka , ], at a rate controlled by the concentration gradient.…”

Section: Introductionmentioning

confidence: 99%

Hydraulics are a first‐order control on CO₂ efflux from fluvial systems

et al. 2015

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Evasion of carbon dioxide (CO 2 ) from fluvial systems is now recognized as a significant component of the global carbon cycle. However, the magnitude of, and controls on, this flux remains uncertain, and improved understanding of both is required to refine global estimates of fluvial CO 2 efflux. CO 2 efflux data show no pattern with latitude suggesting that catchment biological productivity is not a primary control and that an alternative explanation for intersite variability is required. It has been suggested that increased flow velocity and turbulence enhance CO 2 efflux, but this is not confirmed. Here using contemporaneous measurements of efflux (range: 0.07-107 μmol CO 2 m À2 s À1), flow hydraulics (mean velocity range: 0.03-1.39 m s À1 ), and pCO 2 (range: 174-10712 μatm) at six sites, we find that flow intensity is a primary control on efflux across two climatically different locations (where pH is not a limiting factor) and that the relationship is refined by incorporating the partial pressure of CO 2 (pCO 2 ) of the water. A remaining challenge is how to upscale from point to reach or river basin level. Remote imaging or river surface may be worth exploring if subjectivity in interpreting surface state can be overcome.

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Stream metabolism and the open diel oxygen method: Principles, practice, and perspectives

Demars

Thompson

Manson

2015

Limnology & Ocean Methods

117

123

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Global quantitative estimations of ecosystem functions are vital. Among those, ecosystem respiration and photosynthesis contribute to carbon cycling and energy flow to food webs. These can be estimated in streams with the open channel diel oxygen method (single or two stations) essentially relying on a mass balance of oxygen over a defined reach. The method is generally perceived as low cost and easy to apply with new drift free optic sensors. Yet, it remains challenging on several key issues reviewed here: measurements of gas transfer at the air-water interface, appropriate mixing of tracers, uncertainty propagation in the calculations, spatial heterogeneity in oxygen concentrations, the derivation of net primary production (NPP) or autotrophic respiration, and the temperature dependence of photosynthesis and respiration. An extremely simple modeling tool is presented in an Excel workbook recommended for teaching the basic principles of the method. The only method able to deal with stream spatial heterogeneity is the method by Demars et al. Example data, Excel workbook, and R script are provided to run stream metabolism calculations. Direct gas exchange determination is essential in shallow turbulent streams, but modeling may be more accurate in large (deep) rivers. Lateral inflows should be avoided or well characterized. New methods have recently been developed to estimate NPP using multiple diel oxygen curves. The metabolic estimates should not be systematically temperature corrected to compare streams. Other recent advances have improved significantly the open channel diel oxygen method, notably the estimation of respiration during daylight hours.

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Assessing the Performance of Reaeration Prediction Equations

Cited by 24 publications

References 17 publications

Headwater gas exchange quantified from O₂ mass balances at the reach scale

Headwater gas exchange quantified from O₂ mass balances at the reach scale

Hydraulics are a first‐order control on CO₂ efflux from fluvial systems

Stream metabolism and the open diel oxygen method: Principles, practice, and perspectives

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Assessing the Performance of Reaeration Prediction Equations

Cited by 24 publications

References 17 publications

Headwater gas exchange quantified from O2 mass balances at the reach scale

Headwater gas exchange quantified from O2 mass balances at the reach scale

Hydraulics are a first‐order control on CO2 efflux from fluvial systems

Stream metabolism and the open diel oxygen method: Principles, practice, and perspectives

Contact Info

Product

Resources

About

Headwater gas exchange quantified from O₂ mass balances at the reach scale

Headwater gas exchange quantified from O₂ mass balances at the reach scale

Hydraulics are a first‐order control on CO₂ efflux from fluvial systems