Scientia Marina, Vol 74, No S1 (2010)

Accumulation of phosphorus in coastal marine sediments: relationship to benthic and diffusive fluxes


https://doi.org/10.3989/scimar.2010.74s1115

Rocio Ponce
Facultad de Ciencias del Mar, Universidad de Cádiz, Spain

Teodora Ortega
Facultad de Ciencias del Mar, Universidad de Cádiz, Spain

Jesús M. Forja
Facultad de Ciencias del Mar, Universidad de Cádiz, Spain

Abelardo Gómez-Parra
Facultad de Ciencias del Mar, Universidad de Cádiz, Spain

Abstract


Sedimentary phosphorus was characterized in sediment cores from 3 coastal ecosystems of the Gulf of Cadiz. High spatial variability was observed in total phosphorus (from 445 to 20291 μg g.sed-1) and in the other phosphorus phases studied. This variability correlates with the proximity of the 10 sampling stations to sources of urban and/or industrial effluent in the zone. The benthic and diffusive fluxes were measured concurrently with sediment collection at these stations. The measured values of benthic fluxes range between –14 and 6 mmol m-2 d-1. Generally, stations that showed increased interstitial phosphate concentrations with increasing depth were characterized by positive values in phosphate benthic fluxes and by high percentages of reactive forms of sedimentary phosphorus. Negative benthic fluxes were associated with stations receiving more anthropogenic matter, which showed progressively decreasing phosphate concentrations in the interstitial water with depth. In these anthropogenic areas, the non-reactive forms of phosphorus (those associated with ferric oxyhydroxide and authigenic carbonate fluorapatite) are abundant, and reach values exceeding 75% of total phosphorus in sediment.

Keywords


benthic fluxes; diffusive fluxes; phosphorus; sediment; Gulf of Cadiz; sequential extraction

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