Biogeochemical Zones Within a Macrotidal, Dry-Tropical Fluvial-Marine Transition Area: A Dry-Season Perspective

The Fitzroy River delivers large amounts of nutrients and fine sediments to Keppel Bay (contiguous with the Great Barrier Reef Lagoon) during intermittent flow events. This study explores sources, forms and transformations of nutrients in Keppel Bay, and develops a functional process zonation that i...

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Bibliographic Details
Published in:Aquatic geochemistry 2010-01, Vol.16 (1), p.1-29
Main Authors: Radke, L. C, Ford, P. W, Webster, I. T, Atkinson, I, Douglas, G, Oubelkheir, K, Li, J, Robson, B, Brooke, B
Format: Article
Language:English
Subjects:
Bathymetry
Biogeochemistry
Coasts
Dry season
Earth and Environmental Science
Earth Sciences
Geochemistry
Hydrogeology
Hydrology/Water Resources
Lagoons
Light penetration
Marine
Mineralization
Nutrient uptake
Ocean floor
Oceans
Organic matter
Original Paper
Phytoplankton
Rivers
Sediments
Suspended sediments
Water column
Water Quality/Water Pollution
Zonation
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Summary:The Fitzroy River delivers large amounts of nutrients and fine sediments to Keppel Bay (contiguous with the Great Barrier Reef Lagoon) during intermittent flow events. This study explores sources, forms and transformations of nutrients in Keppel Bay, and develops a functional process zonation that integrates seabed geochemistry and water column nutrient characteristics which are controlled by suspended sediment. The water column and seabed properties were investigated over two dry seasons, with supplementary core incubations taken to measure carbon decomposition rates and nutrient fluxes. Keppel Bay can be divided into three zones, the: zone of maximum resuspension (ZMR); coastal transitional zone (CTZ); and blue water zone (BWZ). Mineralisation of predominantly terrestrial organic matter occurs in the ZMR where nutrient uptake by phytoplankton is light limited. The CTZ and BWZ had higher light penetration and phytoplankton growth was likely limited by N and P, respectively. The identified zones conform to the bathymetry and hydrodynamic characteristics of the bay, allowing for the development of an integrated conceptual model accounting for the benthic and pelagic biogeochemical processes. Recognition of these different zones shows that considerable variation in benthic and water column properties is possible within a small system with the bathymetric and hydrodynamic characteristics of the fluidized bed reactor.
ISSN:1380-6165
1573-1421
DOI:10.1007/s10498-009-9070-7