Bottom mixed layer oxygen dynamics in the Celtic Sea

Hull, Tom, Johnson, Martin, Greenwood, Naomi and Kaiser, Jan (2020) Bottom mixed layer oxygen dynamics in the Celtic Sea. Biogeochemistry, 149. 263–289. ISSN 0168-2563

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Abstract

The seasonally stratified continental shelf seas are highly productive, economically important environments which are under considerable pressure from human activity. Global dissolved oxygen concentrations have shown rapid reductions in response to anthropogenic forcing since at least the middle of the twentieth century. Oxygen consumption is at the same time linked to the cycling of atmospheric carbon, with oxygen being a proxy for carbon remineralisation and the release of CO2. In the seasonally stratified seas the bottom mixed layer (BML) is partially isolated from the atmosphere and is thus controlled by interplay between oxygen consumption processes, vertical and horizontal advection. Oxygen consumption rates can be both spatially and temporally dynamic, but these dynamics are often missed with incubation based techniques. Here we adopt a Bayesian approach to determining total BML oxygen consumption rates from a high resolution oxygen time-series. This incorporates both our knowledge and our uncertainty of the various processes which control the oxygen inventory. Total BML rates integrate both processes in the water column and at the sediment interface. These observations span the stratified period of the Celtic Sea and across both sandy and muddy sediment types. We show how horizontal advection, tidal forcing and vertical mixing together control the bottom mixed layer oxygen concentrations at various times over the stratified period. Our muddy-sand site shows cyclic spring-neap mediated changes in oxygen consumption driven by the frequent resuspension or ventilation of the seabed. We see evidence for prolonged periods of increased vertical mixing which provide the ventilation necessary to support the high rates of consumption observed.

Item Type: Article
Additional Information: Correction at: 10.1007/s10533-020-00681-8
Uncontrolled Keywords: bayesian model,benthic biogeochemistry,deoxygenation,horizontal advection,oxygen consumption,shelf sea,total oxygen uptake,environmental chemistry,water science and technology,earth-surface processes ,/dk/atira/pure/subjectarea/asjc/2300/2304
Faculty \ School: Faculty of Science > School of Environmental Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 14 May 2020 00:07
Last Modified: 17 Jul 2020 23:44
URI: https://ueaeprints.uea.ac.uk/id/eprint/75146
DOI: 10.1007/s10533-020-00662-x

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