Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

Type Article
Date 2019-10
Language English
Author(s) Hernandez-Ayon Jose M.1, Paulmier Aurélien2, Garcon Veronique9, Sudre Joel9, Montes Ivonne3, Chapa-Balcorta Cecilia4, Durante Giovanni1, Dewitte Boris5, 6, 7, 10, Maes Christophe8, 10, Bretagnon Marine11
Affiliation(s) 1 : Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Ensenada, Mexico
2 : LEGOS, CNRS/IRD/UPS/CNES UMR 5566, Université de Toulouse, Toulouse, France
3 : Instituto Geofísico del Peru, Lima, Peru
4 : Facultad de Ciencias Marinas, Universidad del Mar, Oaxaca, Mexico
5 : Centro de Estudios Avanzado en Zonas Áridas (CEAZA), Coquimbo, Chile
6 : Departamento de Biología, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile
7 : Millennium Nucleus for Ecology and Sustainable Management of Oceanic Islands (ESMOI), Coquimbo, Chile
8 : LOPS (Univ. Brest/IRD/CNRS/IFREMER), Plouzané, France
9 : LEGOS, CNRS/IRD/UPS/CNES UMR 5566, Université de Toulouse, Toulouse, France
10 : LEGOS, CNRS/IRD/UPS/CNES UMR 5566, Université de Toulouse, Toulouse, France
11 : LEGOS, CNRS/IRD/UPS/CNES UMR 5566, Université de Toulouse, Toulouse, France
Source Frontiers In Marine Science (2296-7745) (Frontiers Media SA), 2019-10 , Vol. 6 , N. 617 , P. 16p.
DOI 10.3389/fmars.2019.00617
WOS© Times Cited 5
Keyword(s) OMZ, DIC, pH, omega aragonite, upwelling Peruvian system
Abstract

The oxygen minimum zone (OMZ) of Peru is recognized as a source of CO2 to the atmosphere due to upwelling that brings water with high concentrations of dissolved inorganic carbon (DIC) to the surface. However, the influence of OMZ dynamics on the carbonate system remains poorly understood given a lack of direct observations. This study examines the influence of a coastal Eastern South Pacific OMZ on carbonate system dynamics based on a multidisciplinary cruise that took place in 2014. During the cruise, onboard DIC and pH measurements were used to estimate pCO2 and to calculate the calcium carbonate saturation state (Ω aragonite and calcite). South of Chimbote (9°S), water stratification decreased and both the oxycline and carbocline moved from 150 m depth to 20–50 m below the surface. The aragonite saturation depth was observed to be close to 50 m. However, values <1.2 were detected close to 20 m along with low pH (minimum of 7.5), high pCO2 (maximum 1,250 μatm), and high DIC concentrations (maximum 2,300 μmol kg−1). These chemical characteristics are shown to be associated with Equatorial Subsurface Water (ESSW). Large spatial variability in surface values was also found. Part of this variability can be attributed to the influence of mesoscale eddies, which can modify the distribution of biogeochemical variables, such as the aragonite saturation horizon, in response to shallower (cyclonic eddies) or deeper (anticyclonic eddies) thermoclines. The analysis of a 21-year (1993–2014) data set of mean sea surface level anomalies (SSHa) derived from altimetry data indicated that a large variance associated with interannual timescales was present near the coast. However, 2014 was characterized by weak Kelvin activity, and physical forcing was more associated with eddy activity. Mesoscale activity modulates the position of the upper boundary of ESSW, which is associated with high DIC and influences the carbocline and aragonite saturation depths. Weighing the relative importance of each individual signal results in a better understanding of the biogeochemical processes present in the area.

Full Text
File Pages Size Access
Publisher's official version 16 3 MB Open access
Top of the page

How to cite 

Hernandez-Ayon Jose M., Paulmier Aurélien, Garcon Veronique, Sudre Joel, Montes Ivonne, Chapa-Balcorta Cecilia, Durante Giovanni, Dewitte Boris, Maes Christophe, Bretagnon Marine (2019). Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone. Frontiers In Marine Science, 6(617), 16p. Publisher's official version : https://doi.org/10.3389/fmars.2019.00617 , Open Access version : https://archimer.ifremer.fr/doc/00588/70004/