Evaluation of a lifetime‐based optode to measure oxygen in aquatic systems

Tengberg, Anders; Hovdenes, Jostein; Andersson, Henrik Johan; Brocandel, Olivier; Díaz, Robert J.; Hebert, Dave; Arnerich, Tony; Huber, Christian; Körtzinger, Arne; Khripounoff, Alexis; Rey, Francisco; Rönning, Christer; Schimanski, Jens; Sommer, Stefan; Stangelmayer, Achim

doi:10.4319/lom.2006.4.7

Cited by 214 publications

(207 citation statements)

References 39 publications

(45 reference statements)

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“…The respective tripods were deployed for periods of 6-60 h depending on weather conditions, logistical constraints and the type of instrumentation. One of the tripods always carried a conductivity, temperature, depth (CTD) instrument (XR-420, RBR) equipped with an O 2 optode (Tengberg et al 2006; Aanderaa) to monitor physico-chemical parameters in the bottom water.…”

Section: Study Site and Sampling Campaignsmentioning

confidence: 99%

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

et al. 2016

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Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a *65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated by the brittle star A. filiformis. The numerous burrows were intensively irrigated enhancing the benthic in situ O 2 uptake by *50 %, and inducing highly variable redox conditions and O 2 distribution in the surface sediment as also documented by complementary laboratory-based planar optode measurements. The average benthic O 2 exchange as derived by chamber incubations and the eddy covariance approach were similar (14.9 ± 2.5 and 13.1 ± 9.0 mmol m -2 day -1 ) providing confidence in the two measuring approaches. Moreover, the non-invasive eddy approach revealed a flow-dependent benthic O 2 flux that was partly ascribed to enhanced ventilation of infauna burrows during periods of elevated flow rates. The ratio in exchange rates of RCO 2 and O 2 was close to unity, confirming that the O 2 uptake was a good proxy for the benthic carbon mineralization in this setting. The infauna activity resulted in highly dynamic redox conditions that presumably facilitated an efficient degradation of both terrestrial and marine-derived organic material. The complex O 2 dynamics of the burrow environment also concurrently stimulated nitrification and coupled denitrification rates making the sediment an efficient sink for bioavailable nitrogen. Furthermore, bioturbation mediated a high efflux of dissolved phosphorus and silicate. The study documents a high spatial and temporal variation in benthic solute exchange with important implications for benthic turnover of organic carbon and nutrients. However, more long-term in situ investigations with like approaches are required to fully understand how environmental events and spatio-temporal variations interrelate to the overall biogeochemical functioning of coastal sediments.

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Section: Study Site and Sampling Campaignsmentioning

confidence: 99%

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

et al. 2016

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“…Lifetime is a function of the phase shift of the received red luminesced light (Tengberg et al 2006). The following relationship converts between phase and lifetime: (5) where ϕ [deg] is the measured phase delay under operating conditions, and ϕ o [deg] denotes anoxic conditions (Demas et al 1999).…”

Section: Phase Delay Measurementmentioning

confidence: 99%

“…The commercial Aanderaa optode was described by Tengberg et al (2006). The Aanderaa optode has an external sensing foil in direct contact with seawater.…”

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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“…[10] We applied the selected algorithms for pH e and W arag e (equations (1) and (2), models I and III, [Tengberg et al, 2006;Körtzinger et al, 2005], but the sensor data is not always properly calibrated [Uchida et al, 2008]. To assess the accuracy of the optode-O 2 we compared the first float O 2 profile to a discrete O 2 profile taken at Station P20 16 hours earlier (Figure 1).…”

Section: Predictions Of Ph and W From Argomentioning

confidence: 99%

Real-time estimation of pH and aragonite saturation state from Argo profiling floats: Prospects for an autonomous carbon observing strategy

Juranek¹,

Feely

Gilbert

et al. 2011

Geophys. Res. Lett.

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[1] We demonstrate the ability to obtain accurate estimates of pH and carbonate mineral saturation state (W) from an Argo profiling float in the NE subarctic Pacific. Using hydrographic surveys of the NE Pacific region, we develop empirical algorithms to predict pH and W using observations of temperature (T) and dissolved O 2 . We attain R 2 values greater than 0.98 and RMS errors of 0.018 (pH), 0.052 (W arag ), and 0.087 (W calc ) for data between 30-500 m, s < 27.1. After calibrating optode-based O 2 data, we apply the algorithms to T and O 2 data from an Argo profiling float to produce a 14 month time-series of estimated pH and W arag in the upper water column of the NE subarctic Pacific. Comparison to independent data collected nearby in 2010 indicates pH and W arag estimates are robust. Although the method will not allow detection of anthropogenic trends in pH or W arag , this approach will provide insight into natural variability and the key biogeochemical controls on these parameters. Most importantly, this work demonstrates that an assemblage of well-calibrated regional algorithms and Argo float data can be used as a low-cost, readily-deployable component of a global ocean carbon observing strategy.

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Evaluation of a lifetime‐based optode to measure oxygen in aquatic systems

Cited by 214 publications

References 39 publications

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

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

Real-time estimation of pH and aragonite saturation state from Argo profiling floats: Prospects for an autonomous carbon observing strategy

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