Coupling between sediment biogeochemistry and phytoplankton development in a temperate freshwater marsh (Charente-Maritime, France): Evidence of temporal pattern

WATER RESEARCH

卷:189

Article

Moncelon, Raphael¹  Gouaze, Marie¹  Pineau, Philippe¹  Beneteau, Eric²  Breret, Martine¹  Philippine, Olivier³  Robin, Francois-Xavier³  Dupuy, Christine¹  Metzger, Edouard² 

[1] La Rochelle Univ, Lab LIENSs, UMR 6250, Batiment ILE,2 Rue Olympe de Gouges, La Rochelle, France

[2] Univ Angers, Bioindicateurs Actuels & Fossiles, LPG BIAF, UMR CNRS 6112, 2 Blvd Lavoisier, F-49045 Angers, France

[3] UNIMA, 28 Rue Jacques de Vaucanso, F-17180 Perigny, France

关键词: Freshwater marsh;    Phytoplankton;    Early diagenesis;    Nutrient fluxes;    Nitrogen;    Iron;    Phosphorus;   

DOI  :  10.1016/j.watres.2020.116567

来源: Elsevier

【 摘 要 】

In freshwater systems, sediment can be an important source for the internal loading of PO4. The limiting character of this element in such system leads to consider this phenomenon in terms of eutrophication risks and water quality stakes. A four-months follow-up (January, March, April and May 2019) was carried out in a strong phosphate (PO4) limited secondary channel from an artificial irrigation system of Charente Maritime (France) to link the mobilization of remineralization products in the upper 6 cm layer of sediment (conventional core slicing/centrifugation and DET probes) and the phytoplankton biomass dynamics in the water column. Results showed congruent patterns between the temporal succession of the organic matter mineralization processes in the sediment and the primary biomass dynamics in the water column. In January and March (considered in winter), PO4 proved to be retained by adsorption onto iron oxides in anoxic sediment since pore water nitrate inhibited for about a month the respiration of metal oxides in the first cm of sediment, thus limiting PO4 availability and the phytoplankton growth. In April and May (early spring), after exhaustion of pore water nitrate, the dissolutive reduction of iron oxides released PO4 into pore water generated a significant diffusive outgoing flux from the sediment to the water column with a maximum in April (-1.10E-04 +/- 2.81E-05 nmol cm(-2) s(-1)). This release coincided with the nanophytoplankton bloom (5.50 mu g Chla L-1) and a potential increase of PO4 concentration in the water column. This work provides some insight on the importance of benthic-pelagic coupling in anthropogenic systems. This conceptual model has to be deployed on other sites of interest where internal loading of P takes precedence over external inputs and nitrate mitigation drives its benthic recycling and ultimately its bioavailability. This is to be essential to characterize the aquatic environment quality in order to limit eutrophication risks. (C) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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