FN Archimer Export Format
PT J
TI Methyl mercury distributions in relation to the presence of nano- and picophytoplankton in an oceanic water column (Ligurian Sea, North-western Mediterranean)
BT 
AF HEIMBUERGER, Lars-Eric
   COSSA, Daniel
   MARTY, Jean-Claude
   MIGON, Christophe
   AVERTY, Bernard
   DUFOUR, Aurelie
   RAS, Josephine
AS 1:1,2,3;2:1;3:2,3;4:2,3;5:4;6:2,3;7:2,3;
FF 1:PDG-DOP-LER-LERPAC;2:PDG-DOP-DCN-BE-LBCM;3:;4:;5:PDG-DOP-DCN-BE-LBCM;6:;7:;
C1 IFREMER, Ctr Mediterranee, F-83507 La Seyne Sur Mer, France.
   Univ Paris 06, Observ Oceanol, UMR 7093, F-06234 Villefranche Sur Mer, France.
   CNRS, INSU, Oceanog Lab, UMR 7093, F-06234 Villefranche Sur Mer, France.
   IFREMER, Ctr Nantes, F-44311 Nantes, France.
C2 IFREMER, FRANCE
   UNIV PARIS 06, FRANCE
   CNRS, FRANCE
   IFREMER, FRANCE
SI TOULON
   NANTES
SE PDG-DOP-LER-LERPAC
   PDG-DOP-DCN-BE-LBCM
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 4.101
TC 136
UR https://archimer.ifremer.fr/doc/00013/12415/9206.pdf
   https://archimer.ifremer.fr/doc/00013/12415/9225.pdf
LA English
DT Article
CR BOUSSOLE
AB Recent findings on the distribution of methylated mercury (MeHgT) in waters have highlighted the importance of organic carbon remineralization on the production of these compounds in the open ocean. Here, we present the first time-series (20 monthly samplings between July 2007 and May 2009) of high-resolution vertical profiles (10-12 depths in a 2350 m water column) of MeHgT distributions in an open ocean environment, the Ligurian Sea (North-western Mediterranean Sea). Concentrations varied within the sub-picomolar range (general mean: 0.30 0.17 pmol L-1, n = 214) with the lowest values at the surface, increasing with depth up to the oxygen minimum zone, and decreasing slowly at greater depth. Concentrations in the surface waters never exceeded 0.15 pmol L-1, while the highest concentrations (up to 0.82 pmol L-1) were associated to the hypoxycline during the autumn bloom. A detailed vertical MeHgT profile reveals a "double-peak" pattern, coincidental with the two microbial layers described by Tanaka and Rassoulzadegan (2002), the so-called "microbial food web" in the euphotic zone (<100 m) and the "microbial loop" in the aphotic zone (>100 m). Temporal variations in the MeHgT abundance and distribution in the water column were linked to seasonality. The highest MeHgT concentrations were found in the oxygen minimum zone during the period of stratification, and coincide with the greatest abundance of nano- and picophytoplankton (cyanobacteria, nanoflagellates, etc.) in the euphotic layer. None of our deep MeHgT measurements (-4 00 m above the sea bottom) revealed a significant sedimentary source of MeHgT. We explored the correlation between MeHgT concentrations and the apparent oxygen utilization, a proxy of organic matter remineralization, over the study period. Results of this study strengthen the hypothesis that net mercury methylation in the open ocean occurs in the water column, is linked to organic matter regeneration, and is promoted by the presence of small-sized nano- and picophytoplankton, that dominate under oligotrophic conditions. (C) 2010 Elsevier Ltd. All rights reserved.
PY 2010
PD OCT
SO Geochimica Et Cosmochimica Acta
SN 0016-7037
PU Pergamon-elsevier Science Ltd
VL 74
IS 19
UT 000281423300008
BP 5549
EP 5559
DI 10.1016/j.gca.2010.06.036
ID 12415
ER

EF