Optical proxy for particulate organic nitrogen from BGC-Argo floats

Type Article
Date 2020-07
Language English
Author(s) Fumenia Alain1, Petrenko Anne1, Loisel Hubert2, Djaoudi Kahina3, de Verneil Alain4, Moutin Thierry1
Affiliation(s) 1 : Aix Marseille Université, Université de Toulon, CNRS, IRD, OSU PYTHEAS, Mediterranean Institute of Oceanography (MIO), UM 110, 13288, Marseille, Cedex 09, France
2 : Univ. Littoral Côte d’Opale, CNRS, Univ. Lille, UMR 8187 - LOG - Laboratoire d’Océanologie et de Géosciences, F-62930 Wimereux, France
3 : University of Arizona, department of Molecular and Cellular Biology, 1007 E Lowell Street Life Science South, room 315 Tucson, AZ 85721, USA
4 : The Center for Prototype Climate Modeling, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
Source Optics Express (1094-4087) (The Optical Society), 2020-07 , Vol. 28 , N. 15 , P. 21391-21406
DOI 10.1364/OE.395648
WOS© Times Cited 1

Using biogeochemical-Argo float measurements, we propose, for the first time, an optical proxy for particulate organic nitrogen concentration (PON) in the Western Tropical South Pacific, an area influenced by dinitrogen (N2) fixation. Our results show a significant relationship between the backscattering coefficient at 700 nm (bbp) and PON, especially when the latter is measured using the wet oxidation method (R2=0.87). bbp may be used to estimate PON concentrations (PONopt) between 0.02 and 0.95 ìM, allowing for unprecedented monitoring using autonomous profiling floats. The bbp vs PON relationship can be used to study phytoplanktonic biomass dynamics at relevant seasonal temporal scales, with clear evidence of PONopt as a proxy of phytoplanktonic biomass, at least for this specific area. Temporal analyses of PONopt show significant increases (from 0.16 to 0.80 ìM) likely related to new production associated to N2 fixation events measured during stratification periods in the Melanesian Archipelago

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