Correction of profiles of in-situ chlorophyll fluorometry for the contribution of fluorescence originating from non-algal matter

Type Article
Date 2017-01
Language English
Author(s) Xing Xiaogang1, 2, Claustre Herve3, Boss EmmanuelORCID4, Roesler Collin5, Organelli EmanueleORCID3, 6, Poteau Antoine3, Barbieux Marie3, D'Ortenzio Fabrizio3
Affiliation(s) 1 : State Ocean Adm, State Key Lab Satellite Ocean Environm Dynam, Inst Oceanog 2, Hangzhou, Zhejiang, Peoples R China.
2 : Univ Laval, Takuvik Joint Int Lab & Quebec Ocean, Quebec City, PQ, Canada.
3 : UPMC Univ Paris 06, Sorbonne Univ, LOV, CNRS,UMR 7093, Villefranche Sur Mer, France.
4 : Univ Maine, Sch Marine Sci, Orono, ME USA.
5 : Bowdoin Coll, Dept Earth & Oceanog Sci, Brunswick, ME 04011 USA.
6 : Plymouth Marine Lab, Prospect Pl, Plymouth, Devon, England.
Source Limnology And Oceanography-methods (1541-5856) (Wiley-blackwell), 2017-01 , Vol. 15 , N. 1 , P. 80-93
DOI 10.1002/lom3.10144
WOS© Times Cited 25
Abstract

In situ chlorophyll fluorometers have been widely employed for more than half a century, and to date, it still remains the most used instrument to estimate chlorophyll-a concentration in the field, especially for measurements onboard autonomous observation platforms, e.g., Bio-Argo floats and gliders. However, in deep waters (> 300 m) of some specific regions, e.g., subtropical gyres and the Black Sea, the chlorophyll fluorescence profiles frequently reveal "deep sea red fluorescence" features. In line with previous studies and through the analysis of a large data set (cruise transect in the South East Pacific and data acquired by 82 Bio-Argo floats), we show that the fluorescence signal measured by a humic-like DOM fluorometer is highly correlated to the "deep sea red fluorescence" features. Both fluorescence signals are indeed linearly related in deep waters. To remove the contribution of non-algal organic matter from chlorophyll fluorescence profiles, we introduce a new correction. Rather that removing a constant value (generally the deepest chlorophyll a fluorescence value from the profile, i.e., so-called "deep-offset correction"), we propose a correction method which relies on DOM fluorometry and on its variation with depth. This new method is validated with chlorophyll concentration extracted from water samples and further applied on the Bio-Argo float data set. More generally, we discuss the potential of the proposed method to become a standard and routine procedure in quality-control and correction of chlorophyll a fluorescence originating from Bio-Argo network.

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Xing Xiaogang, Claustre Herve, Boss Emmanuel, Roesler Collin, Organelli Emanuele, Poteau Antoine, Barbieux Marie, D'Ortenzio Fabrizio (2017). Correction of profiles of in-situ chlorophyll fluorometry for the contribution of fluorescence originating from non-algal matter. Limnology And Oceanography-methods, 15(1), 80-93. Publisher's official version : https://doi.org/10.1002/lom3.10144 , Open Access version : https://archimer.ifremer.fr/doc/00661/77327/