La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Labile organic carbon regulates phosphorus release from eroded soil transported into anaerobic coastal systems
Auteurs :	Jouni Lehtoranta, Auteur ; Petri Ekholm, Auteur ; Stella Wahlstrom, Auteur ; Petra Tallberg, Auteur ; Risto Uusitalo, Auteur
Type de document :	Article
Dans :	AMBIO (44 MAR 2015)
Article en page(s) :	S263-S273
Langues:	Anglais
Résumé :	Coastal eutrophication is expected to increase due to expanding and intensifying agriculture which causes a large amount of soil-associated P to be transported into aquatic systems. We performed anaerobic long-term incubations on field soil to mimic the conditions that eroded soil encounters in brackish sediments. The release of P from soil increased with the amount of labile organic C (acetate) addition and decreased with the soil/solution ratio. We deduce that in less-productive brackish systems, microbial Fe reduction allows for the maintenance of the coupled cycling of Fe and P and restricts the amount of P entering the oxic water. In more eutrophic systems, the formation of Fe sulfides as a result of SO4 reduction inactivates Fe, and leads to a higher release of P, thus generating an adverse feedback effect. The dependence of the fate of soil-bound Fe and P on the trophic status of the receiving water should be recognized in eutrophication management.

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