Automated amperometric oxygen titration

Culberson, Charles H.; Huang, Shuilong

doi:10.1016/0198-0149(87)90042-2

Cited by 42 publications

(34 citation statements)

References 6 publications

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“…[6] The Winkler whole bottle titration method with amperometric endpoint detection for dissolved oxygen determination was used [Culberson and Huang, 1987]. Water samples for nitrate plus nitrite (hereafter referred as nitrate), silicate, and phosphate analysis were collected after CFC, dissolved oxygen and total organic carbon samples.…”

Section: Methodsmentioning

confidence: 99%

The N:Si:P molar ratio in the Strait of Gibraltar

Dafner

Boscolo

Bryden

2003

Geophysical Research Letters

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All existing descriptions of nutrient distributions in the Strait of Gibraltar suggest that the Atlantic water brings to the Mediterranean Sea nutrients in the Redfield ratio (N:Si:P = 16:15:1). Here, the N:Si:P molar ratios (±Standard Error), obtained in April 1998, are used to show that in the Atlantic water at the western entrance of the Strait this ratio is lower (13.8(±0.5):12.1(±1.0):1) than the classical Redfield ratio; it is close to the Redfield ratio in the middle of the Strait (15.6(±0.6):10.7(±0.9):1), and increases dramatically to 23.6(±3.4):29.1(±4.5):1 at the eastern entrance of the Strait. In the Mediterranean water, the N:Si:P ratio has a quite similar trend with 31.5(±6.0):26.5(±3.6):1 in the east, 20.4(±0.2):31.5(±11.1):1 in the middle and 18.1(±0.6):17.6(±0.7):1 in the west of the Strait. The physical and biological processes that account for the observed spatial variability of the N:Si:P ratio along the Strait are identified. We estimated that in the Atlantic water entering the Mediterranean Sea, about 84% of the variability in N:Si:P molar ratio is due to biological and 16% to physical processes.

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Section: Methodsmentioning

confidence: 99%

The N:Si:P molar ratio in the Strait of Gibraltar

Dafner

Boscolo

Bryden

2003

Geophysical Research Letters

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“…Oxygen measurements were performed following a standard automated Winkler titration technique with photometric endpoint detection [54] on I06S [39], and amperometric endpoint detection [55] on JC30 and JR239, with a precision less than 0.3 µmol l −1 [40,41].…”

Section: (C) the Antarctic Deep Water Rates Of Export Datasetmentioning

confidence: 99%

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

Brown

Meredith

Jullion

et al. 2014

Phil. Trans. R. Soc. A.

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Full-depth measurements of δ 18 O from 2008 to 2010 enclosing the Weddell Gyre in the Southern Ocean are used to investigate the regional freshwater budget. Using complementary salinity, nutrients and oxygen data, a four-component mass balance was applied to quantify the relative contributions of meteoric water (precipitation/glacial input), sea-ice melt and saline (oceanic) sources. Combination of freshwater fractions with velocity fields derived from a box inverse analysis enabled the estimation of gyre-scale budgets of both freshwater types, with deep water exports found to dominate the budget. Surface net sea-ice melt and meteoric contributions reach 1.8% and 3.2%, respectively, influenced by the summer sampling period, and −1.7% and +1.7% at depth, indicative of a dominance of sea-ice production over melt and a sizable contribution of shelf waters to deep water mass formation. A net meteoric water export of approximately 37 mSv is determined, commensurate with local estimates of ice sheet outflow and precipitation, and the Weddell Gyre is estimated to be a region of net sea-ice production. These results constitute the first synoptic benchmarking of sea-ice and meteoric exports from the Weddell Gyre, against which future change associated with an accelerating hydrological cycle, ocean climate change and evolving Antarctic glacial mass balance can be determined.

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“…The first is the century old Winkler titration technique that involves chemical analysis of seawater samples taken from depth (e.g., Culberson and Huang 1987). It is the primary standard for accurate measurement of dissolved O 2 but requires significant investment in laboratory equipment and personnel training.…”

Section: Introductionmentioning

confidence: 99%

A calibration equation for oxygen optodes based on physical properties of the sensing foil

McNeil

D’Asaro

2014

Limnology & Ocean Methods

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We present a new physically based calibration equation for Aanderaa Inc. oxygen sensing optodes. We use the two site fluorescence quenching model of Demas et al. (1995) to describe the nonlinear Stern-Volmer response of the optode foil to oxygen partial pressure. Seven (minimally six) coefficients quantify foil response to oxygen and temperature; another quantifies response to hydrostatic pressure. These eight coefficients are related, theoretically, to basic physical properties of the foil. The equation provides a framework to study causes of variability and drift in optodes and to develop better quality control and handling procedures. We tested the equation using factory calibrations of 24 optode foils. When accurate multi-point calibration data are unavailable, two additional coefficients empirically correct the usually large differences observed between factory foil calibrations and post-factory laboratory/field calibrations; we cannot eliminate this major cause of uncertainty in optode calibrations. Excluding two potentially anomalous foils, the calibration equation fits 13 similarly calibrated foils, totaling 455 calibration points over 3 -40°C to -0.57 ± 1.48 mbar. Analysis of the resulting best fit coefficients reveals an underlying variability in optodes associated with variability in site 2 and site 1 Stern-Volmer coefficients of 32% and 20%, respectively. The fraction of unquenched fluorophores responding with the more accessible site 1 quenching characteristics varies by only 3%. The equation fits multi-point data for two optodes within manufacturer's specifications, the greater of ± 2.5 μmol . kg -1 and ± 1.5%. Detailed measurements of calibration changes over time will be required to understand the causes of optode drift.

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Automated amperometric oxygen titration

Cited by 42 publications

References 6 publications

The N:Si:P molar ratio in the Strait of Gibraltar

The N:Si:P molar ratio in the Strait of Gibraltar

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O

A calibration equation for oxygen optodes based on physical properties of the sensing foil

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Automated amperometric oxygen titration

Cited by 42 publications

References 6 publications

The N:Si:P molar ratio in the Strait of Gibraltar

The N:Si:P molar ratio in the Strait of Gibraltar

Freshwater fluxes in the Weddell Gyre: results from δ 18 O

A calibration equation for oxygen optodes based on physical properties of the sensing foil

Contact Info

Product

Resources

About

Freshwater fluxes in the Weddell Gyre: results from δ ¹⁸ O