Solid-phase Phosphorus Pools in Highly Organic Carbonate Sediments of Northeastern Florida Bay

Currently, few studies have investigated sediment phosphorus (P) pools or identified the chemical processes important in the P cycle of fine-grained carbonate sediments, particularly in coastal estuaries with high organic matter. To determine the role of fine-grain calcium carbonate and high organic...

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Published in:	Estuarine, coastal and shelf science Vol. 52; no. 2; pp. 279 - 291
Main Authors:	Koch, M.S., Benz, R.E., Rudnick, D.T.
Format:	Journal Article
Language:	English
Published:	London Elsevier Ltd 01-02-2001 Elsevier
Subjects:	Animal and plant ecology Animal, plant and microbial ecology Biological and medical sciences Brackish Fundamental and applied biological sciences. Psychology grain size mangrove Marine nutrients Sea water ecosystems seagrass sub-tropical Synecology Straits of Florida ASW, USA, Florida, Florida Bay grain size sub-tropical mangrove seagrass nutrients Grain size analysis Organic carbonate Environmental factor Phosphorus Biogeochemical cycle Sediments Spatial variation Marine environment Vegetation type Mangrove Nutrient Bay Seagrass bed Solid phase
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Summary:	Currently, few studies have investigated sediment phosphorus (P) pools or identified the chemical processes important in the P cycle of fine-grained carbonate sediments, particularly in coastal estuaries with high organic matter. To determine the role of fine-grain calcium carbonate and high organic matter on sedimentary P, we investigated the solid-phase P pools in seagrass sediments of north-eastern (NE) Florida Bay at the Bay–mangrove ecotone. Sediments were fractionated by sequential extractions into seven chemically-defined groups: exchangeable inorganic and organic P, reducible inorganic and organic P (Fe-bound), acid extractable inorganic and organic P (Ca-bound), and residual organic P. Calcium-bound P accounted for approximately 56% of total P and 96% of inorganic P. Our total calcium-bound P was in the range (34–151μgPg−1) reported for coarse-grained low organic sediments, while the organic P associated with this fraction was slightly (∼10%) higher than those reported for other carbonate systems. The second dominant P fraction was residual organic P (30–71μgPg−1) accounting for 42% of TP. This high residual pool suggests the importance of fringing mangrove and seagrass detritus in long-term P storage. In contrast to temperate estuaries, the iron-bound P fraction in NE Florida Bay sediments was low (<70μgg−1) at the surface and undetectable (<1μgg−1) below 10cm. Based on our findings, we hypothesize that carbonate chemisorption reactions, along with potential reactive organic surfaces, and the sequestering of P into recalcitrant organic pools, maintain low exchangeable and porewater P concentrations across the NE Florida Bay estuary, and account for the reported autotrophic P-limitation.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0272-7714 1096-0015
DOI:	10.1006/ecss.2000.0751