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Phosphorus recyclin...
Phosphorus recycling and burial in Baltic Sea sediments with contrasting redox conditions
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Mort, Haydon P. (författare)
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Slomp, Caroline P. (författare)
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- Gustafsson, Bo G. (författare)
- Stockholms universitet,Baltic Nest Institute
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Andersen, Thorbjorn J. (författare)
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(creator_code:org_t)
- Elsevier BV, 2010
- 2010
- Engelska.
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 74:4, s. 1350-1362
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- In this study, redox-dependent phosphorus (P) recycling and burial at 6 sites in the Baltic Sea is investigated using a combination of porewater and sediment analyses and sediment age dating (Pb-210 and Cs-117). We focus on sites in the Kattegat, Danish Straits and Baltic Proper where present-day bottom water redox conditions range from fully oxygenated and seasonally hypoxic to almost permanently anoxic and sulfidic. Strong surface enrichments of Fe-oxide bound P are observed at oxic and seasonally hypoxic sites but not in the anoxic basins. Reductive dissolution of Fe-oxides and release of the associated P supports higher sediment-water exchange of PO4 at hypoxic sites (up to similar to 800 mu mol P m(-2) d(-1)) than in the anoxic basins. This confirms that Fe-bound P in surface sediments in the Baltic acts as a major internal source of P during seasonal hypoxia, as suggested previously from water column studies. Most burial of P takes place as organic P. We find no evidence for significant authigenic Ca-P formation or biogenic Ca-P burial. The lack of major inorganic P burial sinks makes the Baltic Sea very sensitive to the feedback loop between increased hypoxia, enhanced regeneration of P and increased primary productivity. Historical records of bottom water oxygen at two sites (Bornholm, Northern Gotland) show a decline over the past century and are accompanied by a rise in values for typical sediment proxies for anoxia (total sulfur, molybdenum and organic C/P ratios). While sediment reactive P concentrations in anoxic basins are equal to or higher than at oxic sites, burial rates of P at hypoxic and anoxic sites are up to 20 times lower because of lower sedimentation rates. Nevertheless, burial of reactive P in both hypoxic and anoxic areas is significant because of their large surface area and should be accounted for in budgets and models for the Baltic Sea.
Nyckelord
- EASTERN MEDITERRANEAN SAPROPELS; CONTINENTAL-MARGIN SEDIMENTS; AUTHIGENIC APATITE FORMATION; MARINE-SEDIMENTS; WATER INTERFACE; ORGANIC-MATTER; NORTH-SEA; BRITISH-COLUMBIA; ANOXIC SEDIMENTS; OXYGEN
- NATURAL SCIENCES
- NATURVETENSKAP
- geokemi
- Geochemistry
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