Anomalies of oxygen measurements performed with Aanderaa optodes

Bue, Nadia Lo; Vangriesheim, Annick; Khripounoff, Alexis; Soltwedel, Thomas

doi:10.1080/1755876x.2011.11020125

Cited by 4 publications

(6 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Probably the most striking feature in the data is the episodic occurrence of significant drops in oxygen concentration (up to 100 µmol L −1 ) that can last for minutes to days. Similar anomalies have been reported for optode deployments in the deep central Atlantic and the northwestern Mediterranean Sea (Lo Bue et al, 2011). The detailed analysis of optode and current meter data performed by Lo Bue et al 2011showed that the drops in measured oxygen concentration correlated with low current speeds (<10-12 cm s −1 ) and stochastic flow direction patterns.…”

Section: Challenges In Resolving Gradual Oxygen Changes In the Deep Ssupporting

confidence: 56%

“…The detailed analysis of optode and current meter data performed by Lo Bue et al 2011showed that the drops in measured oxygen concentration correlated with low current speeds (<10-12 cm s −1 ) and stochastic flow direction patterns. In low-current regimes, the corrosion of metallic material in the vicinity of the oxygen sensors (e.g., bottom-lander frame, ballast weights) best explains the conspicuous drops in dissolved oxygen (Lo Bue et al, 2011). Optodes mounted 0.9 m above the seafloor, with an almost equal distance to the ballast weights and the ring of floats on top of the bottom-lander, always showed the lowest fluctuations.…”

Section: Challenges In Resolving Gradual Oxygen Changes In the Deep Smentioning

confidence: 99%

“…1) the position and structure of the chemocline is strongly influenced by anticyclonic gyres located outside of the main Rim Current, as well as by internal waves and the synoptic variability of the Black Sea's circulation pattern (Filonov, 2000). Quasi-periodic and incidental vertical fluctuations of the oxycline and the oxic-anoxic interface have been observed to occur at the Crimean shelf (Luth et al, 1998). The temporal changes in the depth of the oxygensulfide interface cover a range of 130-165 m, corresponding to lateral intrusions of up to 1 km distance along the shelf seafloor.…”

Section: Open and Shelf Seasmentioning

confidence: 99%

See 2 more Smart Citations

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Friedrich¹,

Janßen²,

Aleynik³

et al. 2013

Preprint

View full text Add to dashboard Cite

In this paper we synthesize the new knowledge on oxygen and oxygen-related phenomena in aquatic systems, resulting from the EU-FP7 project HYPOX ("In situ monitoring of oxygen depletion in hypoxic ecosystems of coastal and open seas, and land-locked water bodies", www.hypox.net). In view of the anticipated oxygen loss in aquatic systems due to eutrophication and climate change, HYPOX was set up to improve capacities to monitor hypoxia as well as to understand its causes and consequences. Temporal dynamics and spatial patterns of hypoxia were analysed in field studies in various aquatic environments, including the Baltic Sea, the Black Sea, Scottish and Scandinavian fjords, Ionian Sea lagoons and embayments, and in Swiss lakes. Examples of episodic and rapid (hours) occurrences of hypoxia as well as seasonal changes in bottom-water oxygenation in stratified systems are discussed. Geologically-driven hypoxia caused by gas seepage is demonstrated. Using novel technologies, temporal and spatial patterns of water-column oxygenation, from basin-scale seasonal patterns to meter-scale submicromolar oxygen distributions were resolved. Existing multi-decadal monitoring data were used to demonstrate the imprint of climate change and eutrophication on long-term oxygen distributions. Organic and inorganic proxies were used to extend investigations on past oxygen conditions to centennial and even longer timescales not resolved by monitoring. The effects of hypoxia on faunal communities and biogeochemical processes were also addressed in the project. An investigation of benthic fauna is presented as an example of hypoxia-devastated benthic communities that slowly recover upon a reduction in eutrophication in a system where natural and anthropogenic hypoxia overlap. Biogeochemical investigations reveal that oxygen intrusions have a strong effect on microbially-mediated redox cycling of elements. Observations and modeling studies of the sediments demonstrate the effect of seasonally changing oxygen conditions on benthic mineralization pathways and fluxes. Data quality and access are crucial in hypoxia research. Therefore, technical issues are addressed, including the availability of suitable sensor technology to resolve gradual changes in bottom-water oxygen that can be expected as a result of climate change in deep-sea waters. Using cabled observatories as examples, we show how the benefit of continuous oxygen monitoring can be maximized by adopting proper quality control. Finally, we discuss strategies for state-of-the-art data archiving and dissemination in compliance with global standards and how ocean observations may contribute to global earth observation attempts

show abstract

Section: Challenges In Resolving Gradual Oxygen Changes In the Deep Ssupporting

confidence: 56%

Section: Challenges In Resolving Gradual Oxygen Changes In the Deep Smentioning

confidence: 99%

Section: Open and Shelf Seasmentioning

confidence: 99%

See 1 more Smart Citation

Investigating hypoxia in aquatic environments: diverse approaches to addressing a complex phenomenon

Friedrich¹,

Janßen²,

Aleynik³

et al. 2013

Preprint

View full text Add to dashboard Cite

show abstract

“…This is however not relevant for deepocean environments. As pointed out by (Lo Bue et al, 2011), low current and low dispersion environments are typical for the deep ocean.…”

Section: Current Speedmentioning

confidence: 89%

“…In situations with low currents (ref. previous paragraph) these local dips might not dissipate efficiently (Lo Bue et al, 2011), and the oxygen measurements are therefore less representative of the environment the sensor is intended to measure.…”

Section: Oxygen Optodesmentioning

confidence: 99%

Challenges, limitations, and measurement strategies to ensure data quality in deep-sea sensors

et al. 2023

View full text Add to dashboard Cite

In this paper we give an overview of factors and limitations impairing deep-sea sensor data, and we show how automatic tests can give sensors self-validation and self-diagnostic capabilities. This work is intended to lay a basis for sophisticated use of smart sensors in long-term autonomous operation in remote deep-sea locations. Deep-sea observation relies on data from sensors operating in remote, harsh environments which may affect sensor output if uncorrected. In addition to the environmental impact, sensors are subject to limitations regarding power, communication, and limitations on recalibration. To obtain long-term measurements of larger deep-sea areas, fixed platform sensors on the ocean floor may be deployed for several years. As for any observation systems, data collected by deep-sea observation equipment are of limited use if the quality or accuracy (closeness of agreement between the measurement and the true value) is not known. If data from a faulty sensor are used directly, this may result in an erroneous understanding of deep water conditions, or important changes or conditions may not be detected. Faulty sensor data may significantly weaken the overall quality of the combined data from several sensors or any derived model. This is particularly an issue for wireless sensor networks covering large areas, where the overall measurement performance of the network is highly dependent on the data quality from individual sensors. Existing quality control manuals and initiatives for best practice typically recommend a selection of (near) real-time automated checks. These are mostly limited to basic and straight forward verification of metadata and data format, and data value or transition checks against pre-defined thresholds. Delayed-mode inspection is often recommended before a final data quality stamp is assigned.

show abstract