Authors / CoAuthors
Berelson, W.M. | Heggie, D.T. | Longmore, A. | Udy, J. | Fredericks, D.
Abstract
Measurements of benthic nutrient recycling rates were made at various sites throughout Moreton Bay in February, 1998. Benthic flux chambers were used to define solute exchange rates between the sediments and overlying water column for oxygen (-14 -87 mmol m-2d-1), ammonia (-0.1 - 3.8 mmol m-2d-1), nitrate (-0.1 - 2.1 mmol m-2d-1), phosphate (0.04 - 0.57 mmol m-2d-1), silicic acid (1.0 - 12 mmol m-2d-1), total alkalinity (-44 - 60 meq m-2d-1), TCO2 (26 - 204 mmol m-2d-1), and radon 222 (70 - 490 atoms m-2s-1). Organic carbon oxidation rates were highest in mangrove sediments (~ 200 mmol m-2d-1), were lower within sandy/seagrass sediments (~60 mmol m-2d-1) and generally higher than those measured in muddy sediments (~35 mmol m-2d-1). Diatomaceous phytoplankton debris - partly derived from sewage nutrient inputs - accounts for a large portion of the organic matter diagenesis taking place in the muddy sediments and also to lesser extents in mangrove and sandy/seagrass sediments. Diatoms (because they are heavy and sink) are an important vector, particularly in the muddy sediments, to transport N and P to sedimentary sites of denitrification and P-sequestration. The degree to which muddy sediments return ammonia to the overlying water column is highly dependent on the oxygen concentration of the overlying water. This may reflect a critical instability in the diagenetic/microbiological capacity of muddy sediments to nitrify and denitrify and could result in a positive feedback to increase eutrophication. High denitrification efficiencies were found in the sandy sediments of eastern MB. Naturally occurring radon and introduced tracer Br indicate that bio-irrigation must play an important role in the exchange of solutes across the sediment-water interface.
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nonGeographicDataset
eCat Id
64997
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- External PublicationScientific Journal Paper
- ( Theme )
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- coasts
- ( Theme )
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- marine
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2006-11-03T00:00:00
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