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May 26, 2015 - 1 Sorbonne Universités, Université Pierre et Marie Curie, UMR 7093, ...... Law, C. S., Brévière, E., de Leeuw, G., Garçon, V., Guieu, C., and ...
ORIGINAL RESEARCH published: 26 May 2015 doi: 10.3389/fmars.2015.00027

Dissolved inorganic nitrogen and phosphorus dynamics in seawater following an artificial Saharan dust deposition event Justine Louis 1, 2 , Matthieu Bressac 1, 2 † , Maria L. Pedrotti 1, 2 and Cécile Guieu 1, 2* 1

Edited by: Claire Mahaffey, University of Liverpool, UK Reviewed by: Andrew King, Norwegian Institute for Water Research, Norway Arvind Singh, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany *Correspondence: Cécile Guieu, OOV-Centre National de la Recherche Scientifique, UMR 7093, Observatoire Océanologique de Villefranche, Laboratoire d’Océanographie de Villefranche/Mer, Bat. Jean Maetz, Chemin du Lazaret, 06234 Villefranche/Mer, France [email protected]

Present Address: Matthieu Bressac, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia Specialty section: This article was submitted to Marine Biogeochemistry, a section of the journal Frontiers in Marine Science Received: 06 January 2015 Accepted: 06 May 2015 Published: 26 May 2015 Citation: Louis J, Bressac M, Pedrotti ML and Guieu C (2015) Dissolved inorganic nitrogen and phosphorus dynamics in seawater following an artificial Saharan dust deposition event. Front. Mar. Sci. 2:27. doi: 10.3389/fmars.2015.00027

Sorbonne Universités, Université Pierre et Marie Curie, UMR 7093, Observatoire Océanologique de Villefranche, Laboratoire d’Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer, France, 2 Centre National de la Recherche Scientifique, UMR 7093, Observatoire Océanologique de Villefranche-sur-Mer, Laboratoire d’Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer, France

The dynamics of dissolved inorganic nitrogen and phosphorus in seawater after a dust event were followed to better understand the impact of dust deposition in low nutrient waters of the Mediterranean Sea. Three independent abiotic experiments were performed over three seasons (winter, spring, end of summer) characterized by contrasted biogeochemical conditions. Experiments consisted of seeding evapocondensed Saharan dust at the surface of a polyethylene tank filled with filtered surface seawater. Phosphate (PO34− ), nitrate (NO− 3 ), size and number of particles and transparent exopolymeric particles production (TEP) were measured over the course of 1 week following seeding. Dust deposition was followed by a transient increase in [PO3− 4 ] during the first 3 h with a maximum input of 33, 9, and 39 nM, respectively in May, October and February. The removal of almost all the PO34− initially released suggests a scavenging process of PO3− 4 back onto ferric oxide-rich particles leading to concentrations at the end of the experiment close to the initial values (7 nM in May and October, and 6 nM in February). NO− 3 released from dust was high especially in May and October (maximum input of 23 and 11 μM, respectively) and was attributed to nitrogen dissolution from the large amount of small particles (> 16) and a NP co-limitation in May and 3 /PO4 3− 3− October (NO− 3 /PO4