Influence of post‐<scp>T</scp>ehuano oceanographic processes in the dynamics of the CO<sub>2</sub> system in the <scp>G</scp>ulf of <scp>T</scp>ehuantepec, <scp>M</scp>exico

Chapa-Balcorta, Cecilia; Hernandez-Ayon, J. Martin; Durazo, R.; Beier, Emilio; Alin, Simone R.; López-Pérez, Andrés

doi:10.1002/2015jc011249

Cited by 24 publications

(10 citation statements)

References 69 publications

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“…The DIC concentrations detected in the study area were within the data ranges that have been reported for SSW in the ETP (Paulmier et al, 2011;Franco et al, 2014;Chapa-Balcorta et al, 2015). The DIC variability observed during sampling indicates that upwelling and mesoscale variability affect DIC values.…”

Section: Variability Of Dissolved Inorganic Carbonsupporting

confidence: 81%

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Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

et al. 2019

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The oxygen minimum zone (OMZ) of Peru is recognized as a source of CO 2 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 pCO 2 and to calculate the calcium carbonate saturation state (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 pCO 2 (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.

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Section: Variability Of Dissolved Inorganic Carbonsupporting

confidence: 81%

“…The pH was measured using a glass electrode at 25 • C on the seawater scale (pHsw) as described by Chapa-Balcorta et al (2015). We use the program CO2SYS (Lewis and Wallace, 1998) and DIC-pH sw to calculate pCO 2 , in situ pHsw, and the aragonite saturation state ( Arg ).…”

Section: Methodsmentioning

confidence: 99%

Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

et al. 2019

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“…Journal of Geophysical Research: Oceans velocity and upwelling events have also been reported in the vicinity of the GoT. In Acapulco and Huatulco, where there is a strong vertical salinity gradient (fresh waters overlay saltier subsurface waters) between 30 and 75 m the whole year (Portela et al, 2016), upwelling could be important (Chapa-Balcorta et al, 2015;Kessler, 2006). This process could potentially smooth the salinity tendency, which is in agreement with the effect that the entrainment term has in Acapulco (Figure 10, blue line).…”

Section: 1029/2018jc014265supporting

confidence: 71%

“…This averaging masks, for example, the interannual time scale and the mesoscale features. The latter has been reported to be dominant in the vicinity of the GoT (Barton et al, 2009;Chapa-Balcorta et al, 2015;Trasviña & Barton, 2008;Trasviña et al, 1995). Godínez et al (2010) suggested that from Cabo Corrientes toward the southeast, mesoscale variability increases while seasonal variability decreases and preliminary results of this study confirm this behavior.…”

Section: 1029/2018jc014265supporting

confidence: 68%

Surface Salinity Balance in the Tropical Pacific Off Mexico

et al. 2018

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A simplified analytical model was used to solve the salinity balance equation and study the relative contributions of freshwater flux and salt advection to the salinity tendency between the Gulf of Tehuantepec and Cabo Corrientes (14–22°N). The model used climatological mixed‐layer salinity, satellite‐derived geostrophic velocity and evaporation minus precipitation data in a four‐domain scheme. The mean circulation derived from the model largely coincides with previous reports and suggests that, in the steady state, the Mexican Coastal Current is decoupled from the Tehuantepec region. The analysis of the time‐dependent variability showed that the salt advection can be largely explained by the annual variations of the alongshore velocity (corresponding with the Mexican Coastal Current) and an average salinity. At the seasonal scale, the salt advection and the freshwater flux have similar contributions to the resulting salinity tendency. Near Tehuantepec, due to a local salinity regime, the analytical model does not represent well the observations, while in Manzanillo and Zihuatanejo the agreement between the model and the observations is good in both amplitude and phase. The accuracy of the model in representing the observations is improved in the first third of the year by inclusion of the semiannual scale and the nonlinear processes in the equation of salt advection.

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“…2d). A recent study has shown that the GoT is a source of CO 2 to the atmosphere, with a larger ocean-to-atmosphere flux of CO 2 during well-mixed conditions (Chapa-Balcorta et al, 2015). The trends in shell weight and 18 O sfc-thermo suggest increased upward mixing of subsurface water, which are higher in DIC and lower in pH than surface waters (Chapa-Balcorta et al, 2015), would increase the role of the GoT as a source of CO 2 to the atmosphere as well as influence seawater carbonate chemistry.…”

Section: Regional and Broader Implicationsmentioning

confidence: 99%

Evaluating controls on planktonic foraminiferal geochemistry in the Eastern Tropical North Pacific

Gibson

Thunell

Fehrenbacher

et al. 2016

Earth and Planetary Science Letters

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between mixed-layer species G. ruber and G. bulloides and thermocline-dweller G. menardii track seasonal changes in upwelling. The records suggest an increase in upwelling during the peak positive phase of El Niño, and an overall reduction in stratification over the six-year period. For all three species, Mg/Ca ratios are higher than what has been reported in previous studies, and show poor correlations to calcification temperature. We suggest that low pH (7.6-8.0) and [CO 3 2− ] values (∼70-120 μmol/kg) in the mixed layer contribute to an overall trend of higher Mg/Ca ratios in this region. Laser Ablation Inductively Coupled Mass Spectrometry analyses of G. bulloides with high Mg/Ca ratios (>9 mmol/mol) reveal the presence of a secondary coating of inorganic calcite that has Mg/Ca and Mn/Ca ratios up to an order of magnitude higher than these elemental ratios in the primary calcite, along with elevated Sr/Ca and Ba/Ca ratios. Some of the samples with abnormally high Mg/Ca are found during periods of high primary productivity, suggesting the alteration may be related to changes in carbonate saturation resulting from remineralization of organic matter in oxygen-poor waters in the water column. Although similar shell layering has been observed on fossil foraminifera, this is the first time such alteration has been studied in shells collected from the water column. Our results suggest a role for seawater carbonate chemistry in influencing foraminiferal calcite trace element:calcium ratios prior to deposition on the seafloor, particularly in high-productivity, low-oxygen environments.

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Influence of post‐Tehuano oceanographic processes in the dynamics of the CO₂ system in the Gulf of Tehuantepec, Mexico

Cited by 24 publications

References 69 publications

Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

Surface Salinity Balance in the Tropical Pacific Off Mexico

Evaluating controls on planktonic foraminiferal geochemistry in the Eastern Tropical North Pacific

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Influence of post‐Tehuano oceanographic processes in the dynamics of the CO2 system in the Gulf of Tehuantepec, Mexico

Cited by 24 publications

References 69 publications

Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

Dynamics of the Carbonate System Across the Peruvian Oxygen Minimum Zone

Surface Salinity Balance in the Tropical Pacific Off Mexico

Evaluating controls on planktonic foraminiferal geochemistry in the Eastern Tropical North Pacific

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Product

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Influence of post‐Tehuano oceanographic processes in the dynamics of the CO₂ system in the Gulf of Tehuantepec, Mexico