In situ Study of Bromide Tracer and Oxygen Flux in Coastal Sediments

Laboratory and in situ experiments were performed to assess the use of bromide as a tracer forin situ studies of benthic solute exchange. Bromide was used in the benthic chamber lander ‘Elinor’ for flux measurements in coastal sediments of the German Bight, Kiel Bight and Skagerrak (28–700m water de...

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Bibliographic Details
Published in:Estuarine, coastal and shelf science coastal and shelf science, 1999-12, Vol.49 (6), p.813-827
Main Authors: Forster, S., Glud, R.N., Gundersen, J.K., Huettel, M.
Format: Article
Language:English
Subjects:
bioturbation
bromide tracer
Coastal oceanography, estuaries. Regional oceanography
Denmark, Kiel Bight
Earth, ocean, space
Exact sciences and technology
External geophysics
Germany, German Bight
in situ flux
irrigation
lander
North Sea
oxygen
Physics of the oceans
Scandinavia, Skagerrak
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Summary:Laboratory and in situ experiments were performed to assess the use of bromide as a tracer forin situ studies of benthic solute exchange. Bromide was used in the benthic chamber lander ‘Elinor’ for flux measurements in coastal sediments of the German Bight, Kiel Bight and Skagerrak (28–700m water depth). Tracer and total oxygen uptake were monitored simultaneously in the same chamber incubation. Concurrently, in situ oxygen micro-profiles were recorded at the same locations by the profiling lander ‘Profilur’. Deployment in an anoxic silt (Kiel Bight) confirmed that in the absence of bioturbation and advection, tracer transport into the sediment was driven solely by molecular diffusion. This flux could be well described by a simple box model accounting for molecular diffusion only. In oxic sediments (German Bight and Skagerrak) enhanced exchange of bromide tracer due to bioirrigation parallelled enhanced oxygen uptake equivalent to a 4-fold molecular diffusive flux. Our experiments showed that incubations can be short. Depending on irrigation activity of the fauna, however, incubation length should exceed 3h in order to provide a useful data base for flux calculations. The method demonstrating caveats is discussed and indicate possible improvements. The results show how the bromide tracer addition can be used as a tool for determining solute fluxes exceeding diffusive flux in benthic chamber incubations.
ISSN:0272-7714
1096-0015
DOI:10.1006/ecss.1999.0557