A key role for iron-bound phosphorus in authigenic apatite formation in North Atlantic continental platform sediments
Authors: Caroline P. Slomp; Eric H.G. Epping; Willem Helder; Wim Van Raaphorst
Source: Journal of Marine Research, Volume 54, Number 6, 1 November 1996 , pp. 1179-1205(27)
Publisher: Sears Foundation for Marine Research
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Abstract:
A combination of pore water and solid phase analysis was used to determine whether authigenic carbonate fluorapatite (CFA) is currently forming in the sediment at two locations (OMEX I and II) on the North Atlantic continental platform Goban Spur (southwest of Ireland). Results of selective P extractions suggest that an early diagenetic redistribution of Fe-bound P to an authigenic P phase may be occurring at both stations. A steady-state diagenetic model describing the depth profiles of pore water HPO42- and three solid phase forms of P (organic P, Fe-bound P and authigenic P) was developed and applied to the data of station OMEX-I. The model results indicate that CFA formation can account for the observed increase of authigenic P with depth at this station. Furthermore, the results show that an intense cycling of P between Fe-bound P and pore water HPO42- at the redox interface can create conditions beneficial for CFA formation. This internal P cycle is driven by downward, bioturbational transport of mainly in-situ-formed Fe-bound P into the reduced sediment zone. Losses from the internal P cycle due to CFA formation and HPO42- diffusion are compensated for by sorption of HPO42- released from organic matter to Fe oxides in the oxidized surface sediment. Fe-bound P thus acts as an intermediate between organic P and CFA. CFA can account for between 25 and 70% of the total burial flux of reactive P at station OMEX-I and thus may act as an important sink for P in this low sedimentation, continental margin environment.Document Type: Research article
DOI: 10.1357/0022240963213745
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