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  • 1
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    Diel oxygen production and uptake by Posidonia oceanica meadows at Elba, Italy (2020)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: Aquatic eddy covariance oxygen flux was determined over two seagrass (Posidonia oceanica) meadows at Elba, Italy. The first meadow (open-water) was located 300 m from the southwest corner of the island, and was studied over two continuous days from 15 to 18 May 2016. The second meadow (nearshore) was located 60 m from the north shore of the island, and was studied over two discontinuous days on 13 and 25 May 2017. Both meadows were located at 13 m depth. Eddy covaraince instruments were mounted to a lightweight frame and positioned over seagrass meadows such that the measurement volume was approximately 0.3 m above the top of the canopy. Eddy covariance velocity data were collected at 16 Hz with an acoustic Doppler velocimeter (Vector, Nortek-AS, Norway). Measurements of turbulent fluctuations in oxygen concentration were made 2 cm outside the measuring volume of the Vector using an optode minisensor (O2 Minisensor, Pyroscience GmbH, Germany). The 90% response time of the minisensor was less than 0.3 s. Stable oxygen measurements above and within the canopy were determined with galvanic oxygen sensors (OxyGuard, RBR Ltd., Canada). Eddy covariance fluxes were calculated from the product of turbulent fluctuations in vertical water velocity and oxygen concentration according to standard techniques (see Berg et al., 2003 for details on the aquatic eddy covariance technique, doi:10.3354/meps261075). Further details on calculations of flux, and their correction for the nighttime depletion of oxygen within the seagrass canopy, are presented in the linked manuscript (Koopmans et al., 2020, doi:10.3389/fmars.2020.00118).
    Keywords: Acoustic Doppler Velocimeter (ADV, Nortek Vector); DATE/TIME; dissolved oxygen; Eddy covariance; Elba_nearshore_meadow-1; Elba_nearshore_meadow-2; Elba_open-water_meadow; Elba, Italy; Elevation of event; Event label; Galvanic oxygen sensors (OxyGuard, RBR Ltd., Canada); Irradiance; Latitude of event; Light mode; Longitude of event; Mediterranean; metabolism; Oxygen; Oxygen, flux; Oxygen optode minisensor (O2 Minisensor, PyroScience GmbH, Germany); Photosynthesis; Posidonia oceanica; Seagrass; velocity; Velocity
    Type: Dataset
    Format: text/tab-separated-values, 618 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Suitability analysis and revised strategies for marine environmental carbon capture and storage (CCS) monitoring (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • Approaches for CO2 leakage detection, attribution and quantification monitoring exist. • Many approaches cover multiple monitoring tasks simultaneously. • Sonars and chemical sensors on ships or AUVs can cover large areas. • Newer, more specific technologies can detect, verify and quantify smaller, localised leaks. Environmental monitoring of offshore Carbon Capture and Storage (CCS) complexes requires robust methodologies and cost-effective tools to detect, attribute and quantify CO2 leakage in the unlikely event it occurs from a sub-seafloor reservoir. Various approaches can be utilised for environmental CCS monitoring, but their capabilities are often undemonstrated and more detailed monitoring strategies need to be developed. We tested and compared different approaches in an offshore setting using a CO2 release experiment conducted at 120 m water depth in the Central North Sea. Tests were carried out over a range of CO2 injection rates (6 - 143 kg d−1) comparable to emission rates observed from abandoned wells. Here, we discuss the benefits and challenges of the tested approaches and compare their relative cost, temporal and spatial resolution, technology readiness level and sensitivity to leakage. The individual approaches demonstrate a high level of sensitivity and certainty and cover a wide range of operational requirements. Additionally, we refer to a set of generic requirements for site-specific baseline surveys that will aid in the interpretation of the results. Critically, we show that the capability of most techniques to detect and quantify leakage exceeds the currently existing legal requirements.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Quantification of dissolved CO2 plumes at the Goldeneye CO2-release experiment (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights ● We developed a pH eddy covariance system to detect a sub-seafloor CO2 release. ● It detected CO2 emission to the water column at injection rates of 5.7–143 kg d − 1. ● It was also sensitive enough to quantify benthic biological CO2 production. ● Close to bubble streams, the kinetics of aqueous CO2 equilibration are important. ● This system can be used to detect, attribute, and quantify seafloor sources of CO2. We detected a controlled release of CO2 (g) with pH eddy covariance. We quantified CO2 emission using measurements of water velocity and pH in the plume of aqueous CO2 generated by the bubble streams, and using model predictions of vertical CO2 dissolution and its dispersion downstream. CO2 (g) was injected 3 m below the floor of the North Sea at rates of 5.7–143 kg d − 1. Instruments were 2.6 m from the center of the bubble streams. In the absence of injected CO2, pH eddy covariance quantified the proton flux due to naturally-occurring benthic organic matter mineralization (equivalent to a dissolved inorganic carbon flux of 7.6 ± 3.3 mmol m − 2 d − 1, s.e., n = 33). At the lowest injection rate, the proton flux due to CO2 dissolution was 20-fold greater than this. To accurately quantify emission, the kinetics of the carbonate system had to be accounted for. At the peak injection rate, 73 ± 13% (s.d.) of the injected CO2 was emitted, but when kinetics were neglected, the calculated CO2 emission was one-fifth of this. Our results demonstrate that geochemical techniques can detect and quantify very small seafloor sources of CO2 and attribute them to natural or abiotic origins.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    High Net Primary Production of Mediterranean seagrass (Posidonia oceanica) Meadows Determined with Aquatic Eddy Covariance (2020)
    In:  EPIC3Frontiers in Marine Science
    Details
    Publication Date: 2020-03-12
    Description: We report primary production and respiration of Posidonia oceanica meadows determined with the non-invasive aquatic eddy covariance technique. Oxygen fluxes were measured in late spring at an open-water meadow (300 m from shore), at a nearshore meadow (60 m from shore), and at an adjacent sand bed. Despite the oligotrophic environment, the meadows were highly productive and highly autotrophic. Net ecosystem production (54 to 119 mmol m-2 d-1) was about one-half of gross primary production. In adjacent sands, net primary production was a tenth- to a twentieth smaller (4.6 mmol m-2 d-1). Thus, P. oceanica meadows are an oasis of productivity in unproductive surroundings. During the night, dissolved oxygen was depleted in the open-water meadow. This caused a hysteresis where oxygen production in the late afternoon was greater than in the morning at the same irradiance. Therefore, for accurate measurements of diel primary production and respiration in this system, oxygen must be measured within the canopy. Generally, these measurements demonstrate that P. oceanica meadows fix substantially more carbon than they respire. This supports the high rate of organic carbon accumulation and export for which the ecosystem is known.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 6
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    The response of seagrass (Posidonia oceanica) meadow metabolism to CO2-levels and hydrodynamic exchange determined with aquatic eddy covariance (2018)
    In:  EPIC3Biogeosciences Discussions, 2018, pp. 1-23, ISSN: 1810-6285
    Details
    Publication Date: 2020-02-13
    Description: We investigated light, water velocity, and CO2 as drivers of primary production in Mediterranean seagrass (Posidonia oceanica) meadows and neighboring bare sands using the aquatic eddy covariance technique. Study locations included an open-water meadow and a nearshore meadow, the nearshore meadow being exposed to greater hydrodynamic exchange. A third meadow was located at a CO2 vent. We found that, despite the oligotrophic environment, the meadows had a remarkably high metabolic activity, up to 20 times higher than the surrounding sands. They were strongly autotrophic, with net production half of gross primary production. Thus, P. oceanica meadows are oases of productivity in an unproductive environment. Secondly, we found that turbulent oxygen fluxes above the meadow can be significantly higher in the afternoon than in the morning at the same light levels. This hysteresis can be explained by the replenishment of nighttime-depleted oxygen within the meadow during the morning. Oxygen depletion and replenishment within the meadow do not contribute to turbulent O2 flux. The hysteresis disappeared when fluxes were corrected for the O2 storage within the meadow and, consequently, accurate metabolic rate measurements require measurements of meadow oxygen content. We further argue that oxygen-depleted waters in the meadow provide a source of CO2 and inorganic nutrients for fixation, especially in the morning. Contrary to expectation, meadow metabolic activity at the CO2 vent was lower than at the other sites, with negligible net primary production.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev , info:eu-repo/semantics/article
    Format: application/pdf
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  • 7
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    Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection (2021)
    In:  EPIC3International Journal of Greenhouse Gas Control, 112, pp. 103476, ISSN: 17505836
    Details
    Publication Date: 2021-12-15
    Description: We detected a controlled release of CO2 (g) with pH eddy covariance. We quantified CO2 emission using measurements of water velocity and pH in the plume of aqueous CO2 generated by the bubble streams, and using model predictions of vertical CO2 dissolution and its dispersion downstream. CO2 (g) was injected 3 m below the floor of the North Sea at rates of 5.7–143 kg d-1. Instruments were 2.6 m from the center of the bubble streams. In the absence of injected CO2, pH eddy covariance quantified the proton flux due to naturally-occurring benthic organic matter mineralization (equivalent to a dissolved inorganic carbon flux of 7.6 ± 3.3 mmol m-2 d-1, s.e., n = 33). At the lowest injection rate, the proton flux due to CO2 dissolution was 20-fold greater than this. To accurately quantify emission, the kinetics of the carbonate system had to be accounted for. At the peak injection rate, 73 ± 13% (s.d.) of the injected CO2 was emitted, but when kinetics were neglected, the calculated CO2 emission was one-fifth of this. Our results demonstrate that geochemical techniques can detect and quantify very small seafloor sources of CO2 and attribute them to natural or abiotic origins.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Limitation Availability
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  • 8
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    Quantification of a subsea CO2 release with lab-on-chip sensors measuring benthic gradients (2021)
    In:  EPIC3International Journal of Greenhouse Gas Control, 110, pp. 103427, ISSN: 17505836
    Details
    Publication Date: 2021-12-15
    Description: We present a novel approach to detecting and quantifying a subsea release of CO2 from within North Sea sediments, which mimicked a leak from a subsea CO2 reservoir. Autonomous lab-on-chip sensors performed in situ measurements of pH at two heights above the seafloor. During the 11 day experiment the rate of CO2 release was gradually increased. Whenever the currents carried the CO2-enriched water towards the sensors, the sensors measured a decrease in pH, with a strong vertical gradient within a metre of the seafloor. At the highest release rate, a decrease of over 0.6 pH units was observed 17 cm above the seafloor compared to background measurements. The sensor data was combined with hydrodynamic measurements to quantify the amount of CO2 escaping the sediments using an advective mass transport model. On average, we directly detected 43 ± 8% of the released CO2 in the water column. Accounting for the incomplete carbonate equilibration process increases this estimate to up to 61 ± 10%. This technique can provide long-term in situ monitoring of offshore CO2 reservoirs and hence provides a tool to support climate change mitigation activities. It could also be applied to characterising plumes and quantifying other natural or anthropogenic fluxes of dissolved solutes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
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  • 9
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    Towards improved monitoring of offshore carbon storage: A real-world field experiment detecting a controlled sub-seafloor CO2 release (2021)
    In:  EPIC3International Journal of Greenhouse Gas Control, 106, pp. 103237, ISSN: 17505836
    Details
    Publication Date: 2021-12-15
    Description: Carbon capture and storage (CCS) is a key technology to reduce carbon dioxide (CO2) emissions from industrial processes in a feasible, substantial, and timely manner. For geological CO2 storage to be safe, reliable, and accepted by society, robust strategies for CO2 leakage detection, quantification and management are crucial. The STEMM-CCS (Strategies for Environmental Monitoring of Marine Carbon Capture and Storage) project aimed to provide techniques and understanding to enable and inform cost-effective monitoring of CCS sites in the marine environment. A controlled CO2 release experiment was carried out in the central North Sea, designed to mimic an unintended emission of CO2 from a subsurface CO2 storage site to the seafloor. A total of 675 kg of CO2 were released into the shallow sediments (~3 m below seafloor), at flow rates between 6 and 143 kg/d. A combination of novel techniques, adapted versions of existing techniques, and well-proven standard techniques were used to detect, characterise and quantify gaseous and dissolved CO2 in the sediments and the overlying seawater. This paper provides an overview of this ambitious field experiment. We describe the preparatory work prior to the release experiment, the experimental layout and procedures, the methods tested, and summarise the main results and the lessons learnt.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev , info:eu-repo/semantics/article
    Format: application/pdf
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  • 10
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    Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection (2022)
    Elsevier
    Details
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Koopmans, D., Meyer, V., Schaap, A., Dewar, M., Farber, P., Long, M., Gros, J., Connelly, D., & Holtappels, M. Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection. International Journal of Greenhouse Gas Control, 112, (2021): 103476, https://doi.org/10.1016/j.ijggc.2021.103476.
    Description: We detected a controlled release of CO2 (g) with pH eddy covariance. We quantified CO2 emission using measurements of water velocity and pH in the plume of aqueous CO2 generated by the bubble streams, and using model predictions of vertical CO2 dissolution and its dispersion downstream. CO2 (g) was injected 3 m below the floor of the North Sea at rates of 5.7–143 kg d − 1. Instruments were 2.6 m from the center of the bubble streams. In the absence of injected CO2, pH eddy covariance quantified the proton flux due to naturally-occurring benthic organic matter mineralization (equivalent to a dissolved inorganic carbon flux of 7.6 ± 3.3 mmol m − 2 d − 1, s.e., n = 33). At the lowest injection rate, the proton flux due to CO2 dissolution was 20-fold greater than this. To accurately quantify emission, the kinetics of the carbonate system had to be accounted for. At the peak injection rate, 73 ± 13% (s.d.) of the injected CO2 was emitted, but when kinetics were neglected, the calculated CO2 emission was one-fifth of this. Our results demonstrate that geochemical techniques can detect and quantify very small seafloor sources of CO2 and attribute them to natural or abiotic origins.
    Description: This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 654462 (STEMM-CCS), it also received funding from the Max Planck Society and the Helmholtz Society. MHL was supported by US NSF grant # OCE-1657727.
    Keywords: CO2 vent ; Offshore CCS ; Leakage detection and quantification ; Marine sediment ; Proton flux
    Repository Name: Woods Hole Open Access Server
    Type: Article
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