Home > Research > Publications & Outputs > Headwater gas exchange quantified from O2 mass ...

Electronic data

  • LOM-10-01-004R2 (accepted)

    Accepted author manuscript, 3.81 MB, PDF document

    Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License

Links

Text available via DOI:

View graph of relations

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

Research output: Contribution to journalJournal articlepeer-review

Published
Close
<mark>Journal publication date</mark>10/2018
<mark>Journal</mark>Limnology and Oceanography: Methods
Issue number10
Volume16
Number of pages14
Pages (from-to)696-709
Publication StatusPublished
<mark>Original language</mark>English

Abstract

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 re-aeration coefficient (k2) 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 compartments - sediments) enabling direct hourly estimates of k2 at the reach–scale (~150 m) without relying on the nighttime regression method. Obtained k2 values ranged from 0.001 – 0.600 h-1. Average daytime k2 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 re-aeration. Mean estimates of k 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 <15%), adding further support to the validity of upscaling efforts aiming at quantifying large-scale riverine gas emissions.