High-resolution determination of the pH of seawater with a flow-through system

Fuhrmann, Ruth A.; Zirino, Alberto

doi:10.1016/0198-0149(88)90036-2

Cited by 33 publications

(18 citation statements)

References 6 publications

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“…While they remain the gold standard, the precision of potentiometric pH probes is limited because potential drifts/ uncertainties (up to 0.02 pH units per day) may become difficult to distinguish from the desired change in pH. 8,9 Potentiometric seawater pH measurements have been found to exhibit a precision of about 0.003 pH units, 10 or about 0.2 mV. Ion-selective field-effect transistors (ISFET), on the other hand, gave a precision better than 0.0005 pH units over hours and 0.005 over weeks for the same application.…”

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confidence: 99%

Ultrasensitive Seawater pH Measurement by Capacitive Readout of Potentiometric Sensors

et al. 2020

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Potentiometric pH probes remain the gold standard for the detection of pH but are not sufficiently sensitive to reliably detect ocean acidification at adequate frequency. Here, potentiometric probes are made dramatically more sensitive by placing a capacitive electronic component in series to the pH probe while imposing a constant potential over the measurement circuit. Each sample change now triggers a capacitive current transient that is easily identified between the two equilibrium states, and is integrated to reveal the accumulated charge. This affords dramatically higher precision than with traditional potentiometric probes. pH changes down to 0.001 pH units are easily distinguished in buffer and seawater samples, at a precision (standard deviation) of 28 μpH and 67 μpH, respectively, orders of magnitude better than what is possible with potentiometric pH probes.

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confidence: 99%

Ultrasensitive Seawater pH Measurement by Capacitive Readout of Potentiometric Sensors

et al. 2020

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“…Se realizaron tres calibraciones durante el periodo de nueve días de muestreo y se grabaron las calibraciones por temperatura. Los milivolts fueron normalizados a 2ºC usando la ecuación de Fuhrmann y Zirino (1988), con el objetivo de quitar la dependencia por temperatura y así evaluar sólo las variaciones de pH producidas por cambios de CO 2 . En este trabajo sólo se presentan 2 de los 16 perfiles efectuados en los alrededores de la Isla Elefante en la Antártica y se les identificó como A 1 y A 2 (fig.…”

Section: Metodologíaunclassified

“…A 1 y A 2 indican los puntos donde se realizaron los perfiles. Precisión y exactitud de las mediciones de pH La precisión de las mediciones potenciométricas de pH en flujo continuo descritas por Fuhrmann y Zirino (1988) son de ± 0.003 unidades de pH. Se supuso que la precisión del CTD era similar.…”

Section: Metodologíaunclassified

“…3c) y de 34.5 a 35.5 (∆S = 1) en temperature was recorded. The millivolt values were normalized at 2ºC using the Fuhrmann and Zirino (1988) equation, with the objective of removing the temperature dependency in order to evaluate only the pH variations produced by CO 2 changes. In this work, only 2 of the 16 profiles completed around the Elephant Island area are presented, and they are referred to as A 1 and A 2 (fig.…”

Section: Flujo Continuomentioning

confidence: 99%

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pH-density relationships in seawater

et al. 2003

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“…The pH was computed at 25°C from the response of the glass electrode using the procedure described by Fuhrmann and Zirino (1988) and it was corrected to in situ temperature following Miller0 (1995). Specific alkalinity was assumed constant and equal to 0.120 meq kg.'…”

Section: Methodsmentioning

confidence: 99%

Mixing in the region of the midrift islands of the Gulf of California: effect on surface pCO2

González

Borrego

Zirino³

1997

Cienc. Mar.

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Recibido en agosto de 1996; aceptado en mayo de 1997 RESUMENLa presión parcial del bióxido de carbono (pC0,) y el flujo de CO, a través de la interfase aireagua se estimó para la región de las grandes islas del Golfo de California. Para ello, se utilizaron datos de temperatura (OC), salinidad y pH superficial, recolectados durante el verano de 1990, y se supuso un valor de alcalinidad específica constante. La mezcla por fenómenos asociados con las mareas es particularmente fuerte en esta región del golfo, y nuestro objetivo fue el comparar el efecto de las mareas posvivas con el de las posmuertas. El CO, estuvo cerca del equilibrio o fluyendo del agua hacia el aire, aun con mareas posmuertas. El enfriamiento superficial asociado con las mareas posvivas, con relación a las posmuertas, se presentó con un incremento de la pC0, y del flujo calculado de CO, hacia la atmósfera (~4 mM me2 d-' en mareas posmuertas hasta 23 mM mm2 de' en posvivas). Existe una modulación quincenal de las variables del CO, en las aguas superficiales de esta región debido a la secuencia de las mareas vivas y muertas. La mezcla por mareas es una "bomba física" que acarrea CO, eficientemente de profundidades intermedias (500 m) a la atmósfera en esta región del golfo.Palabras clave: Golfo de California, mezcla por mareas, pC0, superficial, intercambio mar-aire. ABSTRACTSurface seawater carbon dioxide partial pressure (pC0,) and the CO, flux through the air-sea interface in the region of the midrift islands of the Gulf of California were estimated. We used surface temperature ("C), salinity and pH data collected during summer 1990, and we assumed a constant specific alkalinity value. Mixing by tide-related phenomena is particularly strong in this region of the gulf, and our objective was to compare the effect of post-spring tides with that of post-neap tides. Carbon dioxide was either near equilibrium or tlowing from the water to the atmosphere, even with post-neap tidcs. Surface cooling, and larger pC0, and CO, flux were detected with post-spring tides. relativc to post-ncap tides (~4 mM rn-' de' with post-neap tides. up to 23 mM mm2 d-' with post-spring 317 http://dx.doi.org/10.7773/cm.v23i3.813Ciencias Marinas, Val. 23, No. 3. 1997 tides). There is a fortnightly modulation of the CO, system in the surface waters of this region due to the spring-neap tide sequence. Tidal mixing is a "physical pump" that carries CO2 efticiently from intermediate depths (500 m) to the atmosphere in this region of the gulf.Key words: Gulf of California, tidal mixing, surface pCOz, air-sea exchange. INTRODUCCIÓNLas variaciones de los flujos de COZ a través de la interfase océano-atmósfera son un componente importante del ciclo biogeoquí-mico del carbono. La presión parcial del CO, (pC0,) es un parámetro clave del sistema oceánico del CO,. La diferencia entre la pCOI del agua y la del aire define áreas de entrada o emisión de CO, hacia o desde el océano (Wong y Chan, 1991).Los amplios intervalos de marea (>4 m) causan fuerte mezcla vertical en la región de...

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High-resolution determination of the pH of seawater with a flow-through system

Cited by 33 publications

References 6 publications

Ultrasensitive Seawater pH Measurement by Capacitive Readout of Potentiometric Sensors

Ultrasensitive Seawater pH Measurement by Capacitive Readout of Potentiometric Sensors

pH-density relationships in seawater

Mixing in the region of the midrift islands of the Gulf of California: effect on surface pCO2

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