Phosphorus dynamics and bioavailability in sediments of the Penze Estuary (NW France): in relation to annual P-fluxes and occurrences of Alexandrium Minutum

Type Article
Date 2008-05
Language English
Author(s) Andrieux-Loyer Francoise1, Philippon Xavier1, Bally Gabriel1, Kerouel Roger1, Youenou Agnes1, Le Grand Jacqueline1
Affiliation(s) 1 : IFREMER, DYNECO Pelagos, F-29280 Plouzane, France.
Source Biogeochemistry (0168-2563) (Springer), 2008-05 , Vol. 88 , N. 3 , P. 213-231
DOI 10.1007/s10533-008-9199-2
WOS© Times Cited 30
Keyword(s) Sequential extraction, Sediment phosphorus, Pore water, Phosphate fluxes, Estuary, Alexandrium minutum
Abstract The macrotidal estuary of Penze (Brittany, Western part of the Channel, France) has been subjected to recurrent annual toxic blooms of Alexandrium minutum since 1988. This study aims to specify the phosphorus dynamics and bioavailability in sediments in order to improve our understanding of Alexandrium occurrences. Sediment-P pools and diffusive phosphate fluxes were studied under similar hydrodynamic conditions, in the intermediate estuary in May, June and July 2003 and along the salinity gradient from August 2004 to June 2005. The results highlight a decrease in bioavailable phosphorus (iron and organic bound) from the inner part of the estuary seaward. The ratio of iron-bound phosphorus to iron-oxyhydroxides is lower in the inner and intermediate estuaries (5-8) than in the outer site (15), suggesting a saturation of sorption sites and greater phosphorus bioavailability in this area. Pools of bioavailable phosphorus in surficial sediments are about eight times higher than the annual net-export of P (7 ton year(-1)). Phosphate releases from sediments are always lower than 5 mu mol m(-2) d(-1) in March. The highest supplies occur in June and August in the intermediate area (up to 400 mu mol m(-2) d(-1)supercript stop) where they represent up to 50% of river loadings. These results further suggest that phosphate pulses coincide with occurrences of Alexandrium reported in June.
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Andrieux-Loyer Francoise, Philippon Xavier, Bally Gabriel, Kerouel Roger, Youenou Agnes, Le Grand Jacqueline (2008). Phosphorus dynamics and bioavailability in sediments of the Penze Estuary (NW France): in relation to annual P-fluxes and occurrences of Alexandrium Minutum. Biogeochemistry, 88(3), 213-231. Publisher's official version : https://doi.org/10.1007/s10533-008-9199-2 , Open Access version : https://archimer.ifremer.fr/doc/00000/4306/