Standards for Ocean Measurements

Dickson, Andrew

doi:10.5670/oceanog.2010.22

Cited by 119 publications

(109 citation statements)

References 14 publications

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“…Preserved samples, as well as samples directly analyzed onboard, were measured using automated high precision analyzing systems performing a coulometric titration for DIC (SOMMA, Johnson et al, 1993) and a potentiometric titration for TA (VINDTA, Mintrop et al, 2000). The high quality of obtained results was ensured by regular measurements of certified reference material (CRM; A. Dickson, Scripps Institution of Oceanography, La Jolla, USA; Dickson, 2010) and duplicate samples (TA: 1.30 µmol kg −1 , DIC: 1.45 µmol kg −1 ). Results from DIC and TA analysis were used to compute the remaining parameters of the marine carbonate system (pH, pCO 2 and Ar ) using a MATLAB version of the CO2SYS software (Van Heuven et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

et al. 2016

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Abstract. The occurrence of mesoscale eddies that develop suboxic environments at shallow depth (about 40-100 m) has recently been reported for the eastern tropical North Atlantic (ETNA). Their hydrographic structure suggests that the water mass inside the eddy is well isolated from ambient waters supporting the development of severe near-surface oxygen deficits. So far, hydrographic and biogeochemical characterization of these eddies was limited to a few autonomous surveys, with the use of moorings, underwater gliders and profiling floats. In this study we present results from the first dedicated biogeochemical survey of one of these eddies conducted in March 2014 near the Cape Verde Ocean Observatory (CVOO). During the survey the eddy core showed oxygen concentrations as low as 5 µmol kg −1 with a pH of around 7.6 at approximately 100 m depth. Correspondingly, the aragonite saturation level dropped to 1 at the same depth, thereby creating unfavorable conditions for calcifying organisms. To our knowledge, such enhanced acidity within near-surface waters has never been reported before for the open Atlantic Ocean. Vertical distributions of particulate organic matter and dissolved organic matter (POM and DOM), generally showed elevated concentrations in the surface mixed layer (0-70 m), with DOM also accumulating beneath the oxygen minimum. With the use of reference data from the upwelling region where these eddies are formed, the oxygen utilization rate was calculated by determining oxygen consumption through the remineralization of organic matter. Inside the core, we found these rates were almost 1 order of magnitude higher (apparent oxygen utilization rate (aOUR); 0.26 µmol kg −1 day −1 ) than typical values for the open North Atlantic. Computed downward fluxes for particulate organic carbon (POC), were around 0.19 to 0.23 g C m −2 day −1 at 100 m depth, clearly exceeding fluxes typical for an oligotrophic open-ocean setting. The observations support the view that the oxygen-depleted eddies can be viewed as isolated, westwards propagating upwelling systems of their own, thereby represent re-occurring alien biogeochemical environments in the ETNA.

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Section: Methodsmentioning

confidence: 99%

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

et al. 2016

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“…A VINDTA 3C system (Mintrop et al 2000) was used for the determination of both A T by acid potentiometric titration and DIC by coulometry after phosphoric acid addition, with a precision of ± 2 and ± 1 μmol kg −1 , respectively. From 1998 onwards, Certified Reference Material (CRM) was used for all CO 2 analyses (Dickson 2010).…”

Section: Methods and Datamentioning

confidence: 99%

Variability of nutrients and carbon dioxide in the Antarctic Intermediate Water between 1990 and 2014

et al. 2018

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Antarctic Intermediate Water (AAIW) formation constitutes an important mechanism for the export of macronutrients out of the Southern Ocean that fuels primary production in low latitudes. We used quality-controlled gridded data from five hydrographic cruises between 1990 and 2014 to examine decadal variability in nutrients and dissolved inorganic carbon (DIC) in the AAIW (neutral density range 27 < γ n < 27.4) along the Prime Meridian. Significant positive trends were found in DIC (0.70 ± 0.4 μmol kg −1 year −1 ) and nitrate (0.08 ± 0.06 μmol kg −1 year −1 ) along with decreasing trends in temperature (−0.015±0.01 • C year −1 ) and salinity (−0.003±0.002 year −1 ) in the AAIW. Accompanying this is an increase in apparent oxygen utilization (AOU, 0.16 ± 0.07 μmol kg −1 year −1 ). We estimated that 75% of the DIC change has an anthropogenic origin. The remainder of the trends support a scenario of a strengthening of the upper-ocean overturning circulation in the Atlantic sector of the Southern Ocean in response to the positive trend in the Southern Annular Mode. A decrease in net primary productivity (more nutrients unutilized) in the source waters of the AAIW could have contributed as well but cannot fully explain all observed changes.

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“…TAlk was calculated from the volume of acid added at the inflection point closest to a pH of 4, and reported as µmol L −1 HCO − 3 since the original pH of the water samples was near neutral. The precision of the measurements was ±2 % from replicate analysis (n = 5) with an accuracy of ±2 % as determined by analysis of certified reference material (Dickson, 2010). DIC and pH were computed from TAlk and pCO 2 using the dissociation constants of Cai and Wang (1998) for estuarine waters.…”

Section: Total Alkalinity and Dissolved Inorganic Carbonmentioning

confidence: 99%

“…For DIC analysis, water samples were first acidified to convert all the carbonate species to CO 2 in a DIC analyzer (Apollo SciTech), and then measured with a non-dispersive infrared absorption (NDIR) detector (LI-COR LI-7000). Calibrations for DIC and TAlk were performed using certified reference material (Dickson, 2010). The analytical uncertainty of the DIC and TAlk measurements based on replicate samples are 0.1 and 0.2 %, respectively.…”

Section: Total Alkalinity and Dissolved Inorganic Carbonmentioning

confidence: 99%

Dissolved carbon biogeochemistry and export in mangrove-dominated rivers of the Florida Everglades

Ferrón

Engel

et al. 2017

Biogeosciences

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Abstract. The Shark and Harney rivers, located on the southwest coast of Florida, USA, originate in the freshwater, karstic marshes of the Everglades and flow through the largest contiguous mangrove forest in North America. In November 2010 and 2011, dissolved carbon source-sink dynamics was examined in these rivers during SF 6 tracer release experiments. Approximately 80 % of the total dissolved carbon flux out of the Shark and Harney rivers during these experiments was in the form of inorganic carbon, either via air-water CO 2 exchange or longitudinal flux of dissolved inorganic carbon (DIC) to the coastal ocean. Between 42 and 48 % of the total mangrove-derived DIC flux into the rivers was emitted to the atmosphere, with the remaining being discharged to the coastal ocean. Dissolved organic carbon (DOC) represented ca. 10 % of the total mangrove-derived dissolved carbon flux from the forests to the rivers. The sum of mangrove-derived DIC and DOC export from the forest to these rivers was estimated to be at least 18.9 to 24.5 mmol m −2 d −1 , a rate lower than other independent estimates from Shark River and from other mangrove forests.Results from these experiments also suggest that in Shark and Harney rivers, mangrove contribution to the estuarine flux of dissolved carbon to the ocean is less than 10 %.

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Standards for Ocean Measurements

Abstract: C e l e b r at i N g 5 0 Y e a r s o f t h e i N t e r g o V e r N m e N ta l o C e a N o g r a p h i C C o m m i s s i

Cited by 119 publications

References 14 publications

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

Variability of nutrients and carbon dioxide in the Antarctic Intermediate Water between 1990 and 2014

Dissolved carbon biogeochemistry and export in mangrove-dominated rivers of the Florida Everglades

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