The use of buffers to measure the pH of seawater

Millero, Frank J.; Zhang, Jiazhong; Fiol, Sarah; Sotolongo, Sara; Roy, Rabindra N.; Lee, Kitack; Mane, Sanjay

doi:10.1016/0304-4203(93)90199-x

Cited by 106 publications

(92 citation statements)

References 29 publications

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“…The speciation of the carbonate system (in particular pCO 2 ) is calculated based on the knowledge of DIC and total alkalinity (TA), using stoichiometric relationships and apparent equilibrium constants, which are function of temperature, pressure and salinity (Weiss, 1974;Millero et al, 1993). DIC and TA are computed taking into account, respectively, the biological uptake or release of carbon and the phytoplankton assimilation of nitrate, all provided by the MIRO model.…”

Section: Model Descriptionmentioning

confidence: 99%

Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Gypens

Lancelot

Borges³

2004

Biogeosciences

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Abstract.A description of the carbonate system has been incorporated in the MIRO biogeochemical model to investigate the contribution of diatom and Phaeocystis blooms to the seasonal dynamics of air-sea CO 2 exchanges in the Eastern Channel and Southern Bight of the North Sea, with focus on the eutrophied Belgian coastal waters. For this application, the model was implemented in a simplified three-box representation of the hydrodynamics with the open ocean boundary box 'Western English Channel' (WCH) and the 'French Coastal Zone' (FCZ) and 'Belgian Coastal Zone' (BCZ) boxes receiving carbon and nutrients from the rivers Seine and Scheldt, respectively. Results were obtained by running the model for the 1996-1999 period. The simulated partial pressures of CO 2 (pCO 2 ) were successfully compared with data recorded over the same period in the central BCZ at station 330 (51 • 26.05 N; 002 • 48.50 E). Budget calculations based on model simulations of carbon flow rates indicated for BCZ a low annual sink of atmospheric CO 2 (−0.17 mol C m −2 y −1 ). On the opposite, surface water pCO 2 in WCH was estimated to be at annual equilibrium with respect to atmospheric CO 2 . The relative contribution of biological, chemical and physical processes to the modelled seasonal variability of pCO 2 in BCZ was further explored by running model scenarios with separate closures of biological activities and/or river inputs of carbon. The suppression of biological processes reversed direction of the CO 2 flux in BCZ that became, on an annual scale, a significant source for atmospheric CO 2 (+0.53 mol C m −2 y −1 ). Overall biological activity had a stronger influence on the modelled seasonal cycle of pCO 2 than temperature. Especially Phaeocystis colonies which growth in spring were associated with an important sink of atmospheric CO 2 that counteracted the temperature-driven increase of pCO 2 at this period of the year. However, river inputs of organic and inorganic carbonCorrespondence to: N. Gypens (ngypens@ulb.ac.be) were shown to increase the surface water pCO 2 and hence the emission of CO 2 to the atmosphere. Same calculations conducted in WCH, showed that temperature was the main factor controlling the seasonal pCO 2 cycle in these open ocean waters. The effect of interannual variations of fresh water discharge (and related nutrient and carbon inputs), temperature and wind speed was further explored by running scenarios with forcing typical of two contrasted years (1996 and 1999). Based on these simulations, the model predicts significant variations in the intensity and direction of the annual air-sea CO 2 flux.

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Section: Model Descriptionmentioning

confidence: 99%

Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Gypens

Lancelot

Borges³

2004

Biogeosciences

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“…As noted in Easley and Byrne (2012), there are a number of challenges inherent in the potentiometric measurement of pH: calibration buffers must be of similar ionic strength to samples to avoid liquid junction error (see the Discussion section for a complete description of liquid junction error) (Millero et al, 1993;Waters, 2012); preparing saltwater buffers in the lab can lead to pH variation due to human error; post-preparation, the pH of buffers can be altered through contact with ambient atmospheric CO 2 ; electrode function can degrade over time and result in a deviation from the ideal Nernstian slope required to convert volts to pH units; and all electrodes are subject to a certain degree of drift over time (Dickson et al, 2007).…”

Section: Measurement Of Analytical Parametersmentioning

confidence: 99%

“…With appropriate storage protocols, saltwater buffers prepared in this way have proved stable for up to one year, and subsequent degradation is approximately 0.0005 pH units per year (Nemzer and Dickson, 2005). In addition to frequent calibration of pH electrodes to compensate for drift, TRIS and AMP buffers were used to ensure that all electrode responses were within 0.2-0.3 % of the ideal Nernst value (0.05916 V) at 25 • C (Dickson et al, 2007;Millero et al, 1993):…”

Section: Measurement Of Analytical Parametersmentioning

confidence: 99%

Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system

2015

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Abstract. This article describes a potentiometric ocean acidification simulation system which automatically regulates pH through the injection of 100 % CO 2 gas into temperaturecontrolled seawater. The system is ideally suited to longterm experimental studies of the effect of acidification on biological processes involving small-bodied (10-20 mm) calcifying or non-calcifying organisms. Using hobbyist-grade equipment, the system was constructed for approximately USD 1200 per treatment unit (tank, pH regulation apparatus, chiller, pump/filter unit). An overall tolerance of ±0.05 pH T units (SD) was achieved over 90 days in two acidified treatments (7.60 and 7.40) at 12 • C using glass electrodes calibrated with synthetic seawater buffers, thereby preventing liquid junction error. The performance of the system was validated through the independent calculation of pH T (12 • C) using dissolved inorganic carbon and total alkalinity data taken from discrete acidified seawater samples. The system was used to compare the shell growth of the marine gastropod Zeacumantus subcarinatus infected with the trematode parasite Maritrema novaezealandensis with that of uninfected snails at pH levels of 7.4, 7.6, and 8.1.

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“…The pH value, measured according to Butler et al (1985), Dickson (1993a,b), and Millero et al (1993), of each seawater sample was adjusted to 6.0 with CH 3 COONH 4 , as described by Mö ller et al (1992). The sample was loaded into an 8-cm long column filled with CHELEX-100, which had been previously cleaned and conditioned according to Paulson (1986).…”

Section: Seawater Analysismentioning

confidence: 99%

Alteration effects of volcanic ash in seawater: Anomalous Y/Ho ratios in coastal waters of the Central Mediterranean sea

Censi

Sprovieri

Larocca

et al. 2007

Geochimica et Cosmochimica Acta

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This paper presents the results of a study based on data collected during the oceanographic cruise ANSIC 2001 carried out in the Ionian Sea during the explosive activity of Mount Etna in the summer of 2001. Anomalous low values of Y/Ho ratios in seawater suggest extensive scavenging processes on the surfaces of smectitic alteration products, with Y and Ho fractionation controlled by the differences in their electronic configurations and behaviour during solution/surface complexation equilibria. These processes can also be traced through the presence of significant tetrad effects recorded in the chondrite-normalised Rare Earth Elements and Yttrium (YREEs) patterns of suspended particulate matter. This suggests that the preferential Y scavenging from seawater is due to the formation of inner-sphere complexes with OH À groups on montmorillonite crystal surfaces. The preliminary results of kinetic experiments of YREE released from volcanic ash to coexisting seawater, and the related effects on Y/Ho ratios and Ce anomalies, are consistent with the fractionation of Light Rare Earth Elements (LREEs) with respect to Heavy Rare Earth Elements (HREEs) observed in dissolved phase. They suggest a behaviour of Y similar to that reported for LREEs, particularly for Ce and Pr.

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The use of buffers to measure the pH of seawater

Cited by 106 publications

References 29 publications

Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system

Alteration effects of volcanic ash in seawater: Anomalous Y/Ho ratios in coastal waters of the Central Mediterranean sea

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The use of buffers to measure the pH of seawater

Cited by 106 publications

References 29 publications

Carbon dynamics and CO&lt;sub&gt;2&lt;/sub&gt; air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Carbon dynamics and CO&lt;sub&gt;2&lt;/sub&gt; air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system

Alteration effects of volcanic ash in seawater: Anomalous Y/Ho ratios in coastal waters of the Central Mediterranean sea

Contact Info

Product

Resources

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Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study