Literatura académica sobre el tema "Oceanic carbonate system"
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Artículos de revistas sobre el tema "Oceanic carbonate system"
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Li, Futian, Yaping Wu, David A. Hutchins, Feixue Fu y Kunshan Gao. "Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations". Biogeosciences 13, n.º 22 (21 de noviembre de 2016): 6247–59. http://dx.doi.org/10.5194/bg-13-6247-2016.
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Abstract. Diel and seasonal fluctuations in seawater carbonate chemistry are common in coastal waters, while in the open-ocean carbonate chemistry is much less variable. In both of these environments, ongoing ocean acidification is being superimposed on the natural dynamics of the carbonate buffer system to influence the physiology of phytoplankton. Here, we show that a coastal Thalassiosira weissflogii isolate and an oceanic diatom, Thalassiosira oceanica, respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification (OA) scenarios. A fluctuating carbonate chemistry regime showed positive or negligible effects on physiological performance of the coastal species. In contrast, the oceanic species was significantly negatively affected. The fluctuating regime reduced photosynthetic oxygen evolution rates and enhanced dark respiration rates of T. oceanica under ambient CO2 concentration, while in the OA scenario the fluctuating regime depressed its growth rate, chlorophyll a content, and elemental production rates. These contrasting physiological performances of coastal and oceanic diatoms indicate that they differ in the ability to cope with dynamic pCO2. We propose that, in addition to the ability to cope with light, nutrient, and predation pressure, the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species. Habitat-relevant diurnal changes in seawater carbonate chemistry can interact with OA to differentially affect diatoms in coastal and pelagic waters.
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Humphreys, Matthew P., Ernie R. Lewis, Jonathan D. Sharp y Denis Pierrot. "PyCO2SYS v1.8: marine carbonate system calculations in Python". Geoscientific Model Development 15, n.º 1 (4 de enero de 2022): 15–43. http://dx.doi.org/10.5194/gmd-15-15-2022.
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Abstract. Oceanic dissolved inorganic carbon (TC) is the largest pool of carbon that substantially interacts with the atmosphere on human timescales. Oceanic TC is increasing through uptake of anthropogenic carbon dioxide (CO2), and seawater pH is decreasing as a consequence. Both the exchange of CO2 between the ocean and atmosphere and the pH response are governed by a set of parameters that interact through chemical equilibria, collectively known as the marine carbonate system. To investigate these processes, at least two of the marine carbonate system's parameters are typically measured – most commonly, two from TC, total alkalinity (AT), pH, and seawater CO2 fugacity (fCO2; or its partial pressure, pCO2, or its dry-air mole fraction, xCO2) – from which the remaining parameters can be calculated and the equilibrium state of seawater solved. Several software tools exist to carry out these calculations, but no fully functional and rigorously validated tool written in Python, a popular scientific programming language, was previously available. Here, we present PyCO2SYS, a Python package intended to fill this capability gap. We describe the elements of PyCO2SYS that have been inherited from the existing CO2SYS family of software and explain subsequent adjustments and improvements. For example, PyCO2SYS uses automatic differentiation to solve the marine carbonate system and calculate chemical buffer factors, ensuring that the effect of every modelled solute and reaction is accurately included in all its results. We validate PyCO2SYS with internal consistency tests and comparisons against other software, showing that PyCO2SYS produces results that are either virtually identical or different for known reasons, with the differences negligible for all practical purposes. We discuss insights that guided the development of PyCO2SYS: for example, the fact that the marine carbonate system cannot be unambiguously solved from certain pairs of parameters. Finally, we consider potential future developments to PyCO2SYS and discuss the outlook for this and other software for solving the marine carbonate system. The code for PyCO2SYS is distributed via GitHub (https://github.com/mvdh7/PyCO2SYS, last access: 23 December 2021) under the GNU General Public License v3, archived on Zenodo (Humphreys et al., 2021), and documented online (https://pyco2sys.readthedocs.io/en/latest/, last access: 23 December 2021).
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Calvès, Gérôme, Alan Mix, Liviu Giosan, Peter D. Clift, Stéphane Brusset, Patrice Baby y Mayssa Vega. "The Nazca Drift System – palaeoceanographic significance of a giant sleeping on the SE Pacific Ocean floor". Geological Magazine 159, n.º 3 (2 de noviembre de 2021): 322–36. http://dx.doi.org/10.1017/s0016756821000960.
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AbstractThe evolution and resulting morphology of a contourite drift system in the SE Pacific oceanic basin is investigated in detail using seismic imaging and an age-calibrated borehole section. The Nazca Drift System covers an area of 204 500 km2 and stands above the abyssal basins of Peru and Chile. The drift is spread along the Nazca Ridge in water depths between 2090 and 5330 m. The Nazca Drift System was drilled at Ocean Drilling Program Site 1237. This deep-water drift overlies faulted oceanic crust and onlaps associated volcanic highs. Its thickness ranges from 104 to 375 m. The seismic sheet facies observed are associated with bottom current processes. The main lithologies are pelagic carbonates reflecting the distal position relative to South America and water depth above the carbonate compensation depth during Oligocene time. The Nazca Drift System developed under the influence of bottom currents sourced from the Circumpolar Deep Water and Pacific Central Water, and is the largest yet identified abyssal drift system of the Pacific Ocean, ranking third in all abyssal contourite drift systems globally. Subduction since late Miocene time and the excess of sediments and water associated with the Nazca Drift System may have contributed to the Andean orogeny and associated metallogenesis. The Nazca Drift System records the evolution in interactions between deep-sea currents and the eastward motion of the Nazca Plate through erosive surfaces and sediment remobilization.
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Hart, Malcolm B., Wendy Hudson, Christopher W. Smart y Jarosław Tyszka. "A reassessment of ‘<i>Globigerina bathoniana</i>’ Pazdrowa, 1969 and the palaeoceanographic significance of Jurassic planktic foraminifera from southern Poland". Journal of Micropalaeontology 31, n.º 2 (1 de julio de 2012): 97–109. http://dx.doi.org/10.1144/0262-821x11-015.
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Abstract. ‘Globigerina Ooze’, Foraminiferal Ooze or Carbonate Ooze as it is now known, is a widespread and highly characteristic sediment of the modern ocean system. Comparable sediments are much less common in the geological record although, as we describe here, a number of Middle Jurassic carbonate sediments with distinctive assemblages from Central Europe fulfil many of the criteria. One important component of these assemblages in the Middle Jurassic is ‘Globigerina bathoniana’ Pazdrowa, 1969, first described from the Bathonian sediments near Ogrodzieniec (Poland). The generic assignment of this species and other coeval Jurassic taxa is discussed. This species and many of the other early planktic foraminifera evolved in the Aragonite ll Ocean, together with the other two oceanic carbonate producers: the calcareous nannofossils and the calcareous dinoflagellates. The preservation of carbonate sediments with abundant planktic foraminifera on the sea floor indicates that, by the mid-Jurassic, the carbonate/aragonite compensation depths (and associated lysoclines) must have developed in the water column.
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Nisumaa, A. M., S. Pesant, R. G. J. Bellerby, B. Delille, J. Middelburg, J. C. Orr, U. Riebesell, T. Tyrrell, D. Wolf-Gladrow y J. P. Gattuso. "EPOCA/EUR-OCEANS data-mining compilation on the impacts of ocean acidification". Earth System Science Data Discussions 3, n.º 1 (30 de marzo de 2010): 109–30. http://dx.doi.org/10.5194/essdd-3-109-2010.
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Abstract. The uptake of anthropogenic CO2 by the oceans has led to a rise in the oceanic partial pressure of CO2, and to a decrease in pH and carbonate ion concentration. This modification of the marine carbonate system is referred to as ocean acidification. Numerous papers report the effects of ocean acidification on marine organisms and communities but few have provided details concerning full carbonate chemistry and complementary observations. Additionally, carbonate system variables are often reported in different units, calculated using different sets of dissociation constants and on different pH scales. Hence the direct comparison of experimental results has been problematic and often misleading. The need was identified to (1) gather data on carbonate chemistry, biological and biogeochemical properties, and other ancillary data from published experimental data, (2) transform the information into common framework, and (3) make data freely available. The present paper is the outcome of an effort to integrate ocean carbonate chemistry data from the literature which has been supported by the European Network of Excellence for Ocean Ecosystems Analysis (EUR-OCEANS) and the European Project on Ocean Acidification (EPOCA). A total of 166 papers were identified, 86 contained enough information to readily compute carbonate chemistry variables, and 67 datasets were archived at PANGAEA – The Publishing Network for Geoscientific & Environmental Data. This data compilation is regularly updated as an ongoing mission of EPOCA. Data access: http://doi.pangaea.de/10.1594/PANGAEA.735138
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Nisumaa, A. M., S. Pesant, R. G. J. Bellerby, B. Delille, J. J. Middelburg, J. C. Orr, U. Riebesell, T. Tyrrell, D. Wolf-Gladrow y J. P. Gattuso. "EPOCA/EUR-OCEANS data compilation on the biological and biogeochemical responses to ocean acidification". Earth System Science Data 2, n.º 2 (8 de julio de 2010): 167–75. http://dx.doi.org/10.5194/essd-2-167-2010.
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Abstract. The uptake of anthropogenic CO2 by the oceans has led to a rise in the oceanic partial pressure of CO2, and to a decrease in pH and carbonate ion concentration. This modification of the marine carbonate system is referred to as ocean acidification. Numerous papers report the effects of ocean acidification on marine organisms and communities but few have provided details concerning full carbonate chemistry and complementary observations. Additionally, carbonate system variables are often reported in different units, calculated using different sets of dissociation constants and on different pH scales. Hence the direct comparison of experimental results has been problematic and often misleading. The need was identified to (1) gather data on carbonate chemistry, biological and biogeochemical properties, and other ancillary data from published experimental data, (2) transform the information into common framework, and (3) make data freely available. The present paper is the outcome of an effort to integrate ocean carbonate chemistry data from the literature which has been supported by the European Network of Excellence for Ocean Ecosystems Analysis (EUR-OCEANS) and the European Project on Ocean Acidification (EPOCA). A total of 185 papers were identified, 100 contained enough information to readily compute carbonate chemistry variables, and 81 data sets were archived at PANGAEA – The Publishing Network for Geoscientific & Environmental Data. This data compilation is regularly updated as an ongoing mission of EPOCA. Data access: http://doi.pangaea.de/10.1594/PANGAEA.735138
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Zahn, Rainer, Ahmed Rushdi, Nicklas G. Pisias, Brian D. Bornhold, Bertrand Blaise y Robert Karlin. "Carbonate deposition and benthicδ13C in the subarctic Pacific: implications for changes of the oceanic carbonate system during the past 750,000 years". Earth and Planetary Science Letters 103, n.º 1-4 (abril de 1991): 116–32. http://dx.doi.org/10.1016/0012-821x(91)90154-a.
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George, Bivin G., Jyotiranjan S. Ray y Sanjeev Kumar. "Geochemistry of carbonate formations of the Chhattisgarh Supergroup, central India: implications for Mesoproterozoic global events". Canadian Journal of Earth Sciences 56, n.º 3 (marzo de 2019): 335–46. http://dx.doi.org/10.1139/cjes-2018-0144.
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The Chhattisgarh Supergroup is one of the major Proterozoic marine sedimentary sequences of India. It consists of largely undeformed and unmetamorphosed siliciclastic, volcaniclastic, and carbonate formations deposited in two sub-basins, Hirri and Bharadwar, separated by an Archean greenstone belt. In spite of its apparent importance for Mesoproterozoic oceanic records, very few geochemical studies have been carried in the basin. Here, we present results of our high resolution geochemical and C–O–Sr isotopic studies in two carbonate formations of the supergroup: the Charmuria and the Chandi. We observe elevated δ13C values increasing from 2.6‰ to 3.6‰ in these formations, which is consistent with the globally reported late Mesoproterozoic values. Such consistently positive δ13C values are attributed to increased organic carbon burial in the basin margins during the deposition of these carbonates. Based on the principles of δ13C isotope stratigraphy, we suggest a depositional age between 1.0 and 1.2 Ga for these carbonates which form the upper part of the supergroup. The lowest 87Sr/86Sr ratios obtained from the Charmuria and Chandi formations, 0.70723 and 0.70816, respectively, are more radiogenic than the contemporaneous seawater, suggesting that the Sr isotopic system of the formations are altered. Based on the similarity in the δ13C values, we stratigraphically correlate the carbonate formations of the Raipur Group in both the Hirri and Bharadwar sub-basins. We also present a compilation of available δ13C and 87Sr/86Sr records from all the Proterozoic sedimentary successions of India and compare it with the global datasets. We find that while the Indian basins possess records of the Bitter Springs and Shuram δ13C anomalies, they lack evidence for the other major global events of the Proterozoic.
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Wagener, Thibaut, Nicolas Metzl, Mathieu Caffin, Jonathan Fin, Sandra Helias Nunige, Dominique Lefevre, Claire Lo Monaco, Gilles Rougier y Thierry Moutin. "Carbonate system distribution, anthropogenic carbon and acidification in the western tropical South Pacific (OUTPACE 2015 transect)". Biogeosciences 15, n.º 16 (29 de agosto de 2018): 5221–36. http://dx.doi.org/10.5194/bg-15-5221-2018.
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Abstract. The western tropical South Pacific was sampled along a longitudinal 4000 km transect (OUTPACE cruise, 18 February, 3 April 2015) for the measurement of carbonate parameters (total alkalinity and total inorganic carbon) between the Melanesian Archipelago (MA) and the western part of the South Pacific gyre (WGY). This paper reports this new dataset and derived properties: pH on the total scale (pHT) and the CaCO3 saturation state with respect to aragonite (Ωara). We also estimate anthropogenic carbon (CANT) distribution in the water column using the TrOCA method (Tracer combining Oxygen, inorganic Carbon and total Alkalinity). Along the OUTPACE transect a deeper penetration of CANT in the intermediate waters was observed in the MA, whereas highest CANT concentrations were detected in the subsurface waters of the WGY. By combining our OUTPACE dataset with data available in GLODAPv2 (1974–2009), temporal changes in oceanic inorganic carbon were evaluated. An increase of 1.3 to 1.6 µmol kg−1 a−1 for total inorganic carbon in the upper thermocline waters is estimated, whereas CANT increases by 1.1 to 1.2 µmol kg−1 a−1. In the MA intermediate waters (27 kg m−3 <σθ<27.2 kg m−3) an increase of 0.4 µmol kg−1 a−1 CANT is detected. Our results suggest a clear progression of ocean acidification in the western tropical South Pacific with a decrease in the oceanic pHT of up to −0.0027 a−1 and a shoaling of the saturation depth for aragonite of up to 200 m since the pre-industrial period.
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Dumousseaud, C., E. P. Achterberg, T. Tyrrell, A. Charalampopoulou, U. Schuster, M. Hartman y D. J. Hydes. "Contrasting effects of temperature and winter mixing on the seasonal and inter-annual variability of the carbonate system in the Northeast Atlantic Ocean". Biogeosciences Discussions 6, n.º 5 (8 de octubre de 2009): 9701–35. http://dx.doi.org/10.5194/bgd-6-9701-2009.
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Abstract. Future climate change due to the increase in atmospheric CO2 concentrations is expected to strongly affect the oceans, with shallower winter mixing and consequent reduction in primary productivity and oceanic carbon drawdown in low and mid-latitudinal oceanic regions. Here we test this hypothesis by examining the effects of cold and warm winters on the carbonate system in the surface waters of the Northeast Atlantic Ocean for the period between 2005 and 2007. Monthly observations were made between the English Channel and the Bay of Biscay using a ship of opportunity program. During the colder winter of 2005/2006, the maximum depth of the mixed layer reached 500 m in the Bay of Biscay, whilst during the warmer (by 2.6±0.5°C) winter of 2006/2007 the mixed layer depth reached only 300 m. The inter-annual differences in late winter concentrations of nitrate (2.8±1.1 μmol l−1) and dissolved inorganic carbon (22±6 μmol l−1), with higher concentrations at the end of the colder winter (2005/2006), led to differences in the dissolved oxygen anomaly and the fluorescence data for the subsequent growing season. In contrast to model predictions, the calculated air-sea CO2 fluxes (ranging from +4.5 to −5.5 mmol m−2 d−1) showed an increased oceanic CO2 uptake in the Bay of Biscay following the warmer winter of 2006/2007 associated with wind speed and sea surface temperature differences.
Tesis sobre el tema "Oceanic carbonate system"
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Yu, Jimin. "Boron concentration in foraminifera as a proxy for glacial-interglacial change in the oceanic carbonate system". Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614120.
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Wimart-Rousseau, Cathy. "Dynamiques saisonnière et pluriannuelle du système des carbonates dans les eaux de surface en mer Méditerranée". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0503.
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La mer Méditerranée est souvent considérée comme un océan laboratoire pour comprendre les changements globaux liés à l’augmentation de CO2 atmosphérique. Ce travail, basé sur l’étude de données recueilles dans trois régions méditerranéennes, étudie les variations du CO2 océanique dans ce bassin. À l’échelle de la saison, outre les changements de température, le contenu en alcalinité influe sur le contenu en CO2 en Méditerranée orientale, tandis que les changements en carbone total sont responsables des variations dans le bassin occidental. En zone côtière urbanisée, l’émission de CO2 anthropique conditionne les échanges air-mer de CO2. Cette étude montre que l’augmentation de carbone et l’acidification à l’échelle de plusieurs années ne sont pas seulement dues à l’augmentation du CO2 atmosphérique : le contenu en alcalinité module ces tendances dans le bassin oriental, tandis que, dans le bassin occidental, ces tendances sont vraisemblablement influencées par la dynamique des courantsThe Mediterranean Sea is often considered as a laboratory ocean for understanding global changes related to the atmospheric CO2 increase. This work, based on the study of data collected in three Mediterranean regions, investigates the variations of oceanic CO2 in this basin. On a seasonal timescale, in addition to temperature changes, alkalinity content influences the CO2 content in the Eastern Mediterranean, while total carbon changes are responsible for variations in the Western Basin. In urbanised coastal areas, anthropogenic CO2 emission’ influences air-sea CO2 exchanges. This study shows that the carbon increase and the acidification on a multi-year timescale is not only due to the increase in atmospheric CO2: the alkalinity content modulates these trends in the eastern basin, while, in the western basin, these trends are likely influenced by current dynamics
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Planchat, Alban. "Alkalinity and calcium carbonate in Earth system models, and implications for the ocean carbon cycle". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLE005.
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L’alcalinité de l’océan (Alk) est essentielle dans l’absorption de carbone atmosphérique et offre une capacité tampon contre l’acidification. Dans le cadre des prévisions de l’absorption de carbone par les océans et des impacts potentiels sur les écosystèmes, la représentation de l’Alk et du principal facteur de sa distribution dans l’océan profond, le cycle du carbonate de calcium (CaCO3), ont souvent été négligés. Cette thèse aborde le manque de considération accordé à l’Alk et au cycle du CaCO3 dans les modèles du système terrestre (ESM) et explore les implications pour le cycle du carbone dans un océan pré-industriel ainsi que dans des scénarios de changement climatique. À travers une intercomparaison des ESMs, une réduction des biais simulés de l’Alk dans la 6ème phase du Projet d’Intercomparaison de Modèles Couplés (CMIP6) est rapportée. Cette réduction peut s’expliquer partiellement par une calcification pélagique accrue, redistribuant l’Alk en surface et renforçant son gradient vertical dans la colonne d’eau. Une revue des modèles de biogéochimie marine utilisés dans les ESMs actuels révèle une représentation diverse du cycle du CaCO3 et des processus affectant l’Alk. Les schémas de paramétrisation de la production, de l’exportation, de la dissolution et de l’enfouissement du CaCO3 varient considérablement, avec une prise en compte généralement limitée à la seule calcite, et sans calcification benthique. Cette diversité entraîne des projections contrastées de l’export de carbone associé au CaCO3 depuis l’océan de surface vers l’océan profond dans les scénarios futurs. Cependant, des simulations de sensibilité effectuées avec le modèle de biogéochimie marine NEMO-PISCES indiquent que la rétroaction associée sur le flux de carbone anthropique et l’acidification des océans reste limitée. À travers un ensemble de simulations NEMO-PISCES, il est démontré qu’une attention particulière au bilan d’Alk est cruciale pour estimer le dégazage de carbone océanique pré-industriel dû aux apports fluviaux ainsi qu’à l’enfouissement de matière organique et de CaCO3. De telles estimations sont fondamentales pour évaluer le flux de carbone air-mer anthropique en utilisant des données d’observation, et mettent en évidence la nécessité de mieux contraindre le bilan d’Alk de l’océan. Enfin, fidèle au message qu’elle véhicule sur le changement climatique, cette thèse offre une perspective nouvelle et radicale sur les sciences du climat et le système de la recherche actuelOcean alkalinity (Alk) is critical for the uptake of atmospheric carbon and provides buffering capacity against acidification. Within the context of projections of ocean carbon uptake and potential ecosystem impacts, the representation of Alk and the main driver of its distribution in the ocean interior, the calcium carbonate (CaCO3) cycle, have often been overlooked. This thesis addresses the lack of consideration given to Alk and the CaCO3 cycle in Earth system models (ESMs) and explores the implications for the carbon cycle in a pre-industrial ocean as well as under climate change scenarios. Through an ESM intercomparison, a reduction in simulated Alk biases in the 6th phase of the Coupled Model Intercomparison Project (CMIP6) is reported. This reduction can be partially explained by increased pelagic calcification, redistributing Alk at the surface and strengthening its vertical gradient in the water column. A review of the ocean biogeochemical models used in current ESMs reveals a diverse representation of the CaCO3 cycle and processes affecting Alk. Parameterization schemes for CaCO3 production, export, dissolution, and burial vary substantially, with no benthic calcification and generally only calcite considered. This diversity leads to contrasting projections of carbon export associated with CaCO3 from the surface ocean to the ocean interior in future scenarios. However, sensitivity simulations performed with the NEMO-PISCES ocean biogeochemical model indicate that the feedback of this on anthropogenic carbon fluxes and ocean acidification remains limited. Through an ensemble of NEMO-PISCES simulations, careful consideration of the Alk budget is shown to be critical to estimating pre-industrial ocean carbon outgassing due to riverine discharge and the burial of organic matter and CaCO3. Such estimates are fundamental to assessing anthropogenic air-sea carbon fluxes using observational data and highlight the need for greater constraints on the ocean Alk budget
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Beer, Christopher James. "Planktic foraminifera, ocean sediments and the palaeo-marine carbonate system". Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/208361/.
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Legge, Oliver. "The role of carbonate system dynamics in Southern Ocean CO2 uptake". Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/66840/.
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Three years of carbonate system measurements from Ryder Bay on the West Antarctic Peninsula are presented. The strong, asymmetric seasonal cycle of surface water Dissolved Inorganic Carbon (DIC) is quantitatively attributed to four processes:mixing of water masses, air-sea CO2 flux, calcium carbonate precipitation/dissolution and photosynthesis/respiration. In summer, reduced mixing with deeper water, net photosynthesis, and melting glacial ice and sea ice reduce DIC. In winter, mixing with deeper water and net heterotrophy increase DIC, resulting in aragonite saturation states close to 1. Ryder Bay is a net annual sink of atmospheric CO2 of 0.90-1.39 mol C m-2 yr-1. The observed variability demonstrates that future climatic changes may significantly affect carbon cycling in this dynamic environment. Carbonate system measurements from the Drake Passage and A23 sections are compared. Lower Circumpolar Deep Water (LCDW) becomes colder and fresher from Drake Passage to A23 due to mixing in the Scotia Sea. The coincident decrease in Total Alkalinity (TA) increases the fugacity of CO2, potentially reducing CO2 uptake in the Weddell Sea through the influence of upwelling LCDW on surface waters. Ventilation of Upper Circumpolar Deep Water (UCDW) in the south of Drake Passage suggests that this region is an important source of CO2 to the atmosphere. The zonal variability of the carbonate system in deep water masses around the Antarctic Circumpolar Current is assessed. Zonal variability, caused by the inflow of North Atlantic Deep Water in the Atlantic sector and UCDW in the Indian and Pacific sectors, has implications for regional air-sea CO2 flux in the high-latitude Southern Ocean. Temporal variability in Sub-Antarctic ModeWater is investigated. Most of the observed DIC increase is attributed to rising atmospheric CO2. There is also weak evidence for increasing remineralised organic carbon, possibly relatedto changes in the strength and location of ventilation.
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Murphy, Paulette P. "The carbonate system in seawater : laboratory and field studies /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8509.
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Melato, Lebohang Innocentia. "Characterization of the Carbonate System across the Agulhas and Agulhas Return Currents". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15745.
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In this study, we investigate the role that the solubility and biological pumps have on CO₂ variability across the Agulhas Current system ( Agulhas Current and the Agulhas Return Current). The Agulhas Current system transports heat and salt from the Indian Ocean into the South Atlantic Ocean via the Agulhas leakage, which influences the Atlantic Meridional Overturning Circulation (AMOC). This study presents for the first time a characterization of the role the Agulhas Current system (Agulhas and Agulhas Return Currents) has on the uptake of anthropogenic CO₂. Fugacity of carbon dioxide (fCO₂ ) values were obtained from a ship-based underway pCO₂ (partial pressure of carbon dioxide) system and the air-sea CO₂ fluxes were computed using 6-hourly wind speeds from the NOAA Blended Sea Winds. An experiment was conducted during the Crossroads scientific monitoring line in May 2013, where surface dissolved inorganic carbon, total alkalinity and CO₂ flux were compared between the Agulhas and Agulhas Return Currents and the region directly south over the Agulhas Plateau. Our findings highlighted that the solubility and biological pumps played minimal to no role in the drawdown of carbon across the sub-Tropical zone and the Agulhas Current system (Agulhas and Agulhas Return Currents), due to opposing effect between chlorophyll and temperature on pCO₂ that explained why although there was carbon drawdown by primary production in the Agulhas and Agulhas Return Current regions, this does not play a role in enhancing the air-sea exchange of CO₂. The solubility pump was responsible for CO₂ in the sub-Antarctic zone. The biological and solubility pumps were responsible for CO₂ sink in the Agulhas Plateau eddy. The highest CO₂ flux in the study was observed in the Agulhas Plateau eddy at a flux value of -8.12 mmolC.m-².day-¹ due to the cooler mean sea surface temperature of ~16.5 °C. This is the first time that such as study has been undertaken and aims to provide a better understanding of the role of Western Boundary Currents such as the Agulhas Current has in the uptake of CO₂.
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Chanson, Mareva. "The Changes of the Carbonate Parameters in the Ocean: Anthropogenic and Natural Processes". Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/275.
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Since the industrial revolution, CO sub 2 has increased in the atmosphere and about 40% of the increase has been taken up by the ocean. An artifact of increasing CO sub 2 in the ocean is ocean acidification; it changes the calcium carbonate saturation state, which in turn alters the calcification rate of shelled organisms. The purpose of this dissertation is to estimate the changes in the carbonate system in the oceans, and whether these changes are due to natural (biological activity, chemical transformation or mixing of water masses) or anthropogenic (human activities) perturbations. The first hypothesis states that the presence of boric acid (B(OH) sub 3) in seawater changes the thermodynamic constants of CO sub 2, pK sup * sup 1 and pKsup * sup 2. Due to experimental limitations, the solubility of B(OH) sub 3 was determined in electrolyte solutions (LiCl, NaCl, KCl, RbCl and CsCl) instead of real or artificial seawater. The results can be used to estimate the B(OH) sub 3 activity coefficients gamma sub B and solubility [B] in natural mixed electrolyte solutions. The second hypothesis states that filtering seawater sampled in the open ocean is necessary for the determination of total alkalinity (TA). Measurement of 180 samples of surface, oxygen minimum, and deep waters in the Pacific and Indian oceans revealed that the at- sea measured TA of filtered and unfiltered samples were not statistically different. Finally, a synthesis and analysis of the carbonate parameters in the Atlantic and Indian oceans is undertaken. Results from repeat hydrographic cruises in these oceans were used for this task. Parameters TA and total CO sub 2 (TCO sub 2) are predicted using hydrographic properties and a multi-linear regression method to obtain a more homogenous dataset. The results of the predicted TA prove to be successful, which is not the case for TCO sub 2 at the surface of the ocean. Finally, it is found that the increase in anthropogenic CO sub 2 signal remineralization and mixing of water masses increase the acidity of the ocean at the surface and in deep waters, respectively. This causes the aragonite saturation horizon to shoal. Recommendations for further studies are provided in the "Summary and conclusion" chapter.
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Jiang, Zong-Pei. "Variability and control of the surface ocean carbonate system observed from ships of opportunity". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/361858/.
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The surface ocean plays an important role in the marine carbon cycle linking the atmosphere and the deep ocean. There are substantial variations in the surface ocean carbonate system in different environments and on various time scales, resulting from the interactions of various physical and biogeochemical processes. In this study, the use of Ships of Opportunity (SOO, as carriers of automatic underway measuring systems and platforms for sample collections) was promoted to enhance the surface ocean observing capacity to provide in-situ observations with better temporal resolution and spatial coverage in a cost- effective way (Chapter 2). The functionality, reliability and accuracy of an automatic pCO2 sensor were assessed extensively under various field and laboratory conditions (Chapter 3). The sensor proved to be suitable for long-term onboard and in-situ measurements, while its uncertainty is largely determined by the reference used for calibration. Observations made from two SOOs were examined to better understand the variability and control of the surface ocean carbonate system (Chapter 4, 5). The spatial variability of alkalinity in different marine environmental settings were investigated focusing on the influences of physical and biogeochemical processes on the alkalinity-salinity relationship (Chapter 4). By using salinity-normalized alkalinity as an indicator, the TA addition or removal processes were examined in the open ocean regime in the Atlantic, Pacific and Indian Ocean (mainly controlled by precipitation and evaporation), in the western North Atlantic margin, eastern North Pacific and Mediterranean Sea (additional alkalinity inputs from rivers, currents or the Black Sea), and in the Red Sea (alkalinity removal by CaCO3 precipitation). In coastal regions, a regional-specific term for zero salinity end member should be considered in salinity normalization practice, and care should be taken when use the abstract intercept of alkalinity-salinity regression to estimate the river water end member (only works reliably in river-dominated systems). The temporal variations of the surface carbonate system and air-sea CO2 flux in the Northeast Atlantic (Bay of Biscay) were examined on seasonal to interannual time scales (Chapter 5). The seasonal variability of DIC (single annual peak in winter, shaped by the winter increase due to deep convection followed by the spring biological drawdown) is different to the seasonal cycle of pCO2 (double annual peaks in winter and summer, determined by the competing effects of temperature and nonthermal processes on pCO2). A comparative study shows a latitudinal transition of pCO2 seasonality in the North Atlantic: from the temperature-dominated oligotrophic subtropical gyre to the subpolar region where pCO2 is dominated by changing concentrations of DIC. Located in the transition zone, pCO2 in the mid-latitude Bay of Biscay shows a double-peak distribution in its annual cycle: the summer peak is dominated by temperature increase while the winter peak results from the dominant convection effect. The interannual biogeochemical changes in the Bay of Biscay were found to be closely related to the varying intensity of winter mixing, with higher seasonal amplitudes of DIC and nutrients observed in cold years in response to negative phases of the North Atlantic Oscillation. An increase in annual mean seawater pCO2 was observed from 2002 to 2010 associated with decreased rates of oceanic CO2 uptake.
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Stella, Sofia. "Analysis of the Variability of Carbonate System Parameters in the North-East Atlantic". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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The purpose of this thesis is to analyse the spatial and temporal variability of the aragonite saturation state (ΩAR), commonly used as an indicator of ocean acidification, in the North-East Atlantic. When the aragonite saturation state decreases below a certain threshold, ΩAR <1, calcifying organisms (i.e. molluscs, pteropods, foraminifera, crabs, etc.) are subject to dissolution of shells and aragonite structures. This objective agrees with the challenge 'Ocean, climate change and acidification' of the EU COST Ocean Governance for Sustainability project, which aims to combine the information collected on the state of health of the oceans. Two open-sources data products, EMODnet and GLODAPv2, have been integrated and analysed for the first time in the North-East Atlantic region. The integrated dataset contains 1038 ΩAR vertical profiles whose time distribution spans from 1970 to 2014. The ΩAR has been computed from CO2SYS software considering different combinations of input parameters, pH, Total Alkalinity (TAlk) and Dissolved Inorganic Carbon (DIC), associated with Temperature, Salinity and Pressure at in situ conditions. A sensitivity analysis has been performed to better understand the data consistency of ΩAR computed from the different combinations of pH, Talk and DIC and to verify the difference among observed TAlk and DIC parameters and their output values from the CO2SYS tool. Maps of ΩAR have been computed with the best data coverage obtained from the two datasets, at different levels of depth in the area of investigation and they have been compared to the work of Jiang et al. (2015). The results are consistent and show similar horizontal and vertical patterns. The study highlights some aragonite undersaturated values (ΩAR <1) below 500 meters depth, suggesting a potential effect of acidification in the considered time period. This thesis aims to be a preliminary work for future studies that will be able to design the ΩAR variability on a decadal distribution based on the extended time-series acquired in this work.
Libros sobre el tema "Oceanic carbonate system"
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Cool-water carbonates: Depositional systems and palaeoenvironmental controls. London: The Geological Society, 2006.
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(Editor), H. M. Pedley y G. Carannante (Editor), eds. Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls (Geological Society Special Publication). Geological Society of London, 2006.
Buscar texto completoCapítulos de libros sobre el tema "Oceanic carbonate system"
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Bijma, J., H. J. Spero y D. W. Lea. "Reassessing Foraminiferal Stable Isotope Geochemistry: Impact of the Oceanic Carbonate System (Experimental Results)". En Use of Proxies in Paleoceanography, 489–512. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-58646-0_20.
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Henriet, J. P. y S. Guidard. "Carbonate Mounds as a Possible Example for Microbial Activity in Geological Processes". En Ocean Margin Systems, 439–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-05127-6_27.
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Zhai, Wei-dong, Li-wen Zheng, Cheng-long Li, Tian-qi Xiong y Song-yin Wang. "Changing Nutrients, Dissolved Oxygen and Carbonate System in the Bohai and Yellow Seas, China". En Atmosphere, Earth, Ocean & Space, 121–37. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4886-4_8.
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Erlenkeuser, H. y U. von Grafenstein. "Stable Oxygen Isotope Ratios in Benthic Carbonate Shells of Ostracoda, Foraminifera, and Bivalvia from Surface Sediments of the Laptev Sea, Summer 1993 and 1994". En Land-Ocean Systems in the Siberian Arctic, 503–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60134-7_39.
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"Oceans and Estuaries". En Biotic Feedbacks in the Global Climatic System, editado por George M. Woodwell y Fred T. Mackenzie, 231–32. Oxford University PressNew York, NY, 1995. http://dx.doi.org/10.1093/oso/9780195086409.003.0014.
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Abstract The oceans are absorbing carbon dioxide at the rate of 2 ± 1 petagrams of carbon per year. Experience and theory based on experience suggest that the warming projected on the basis of meteorological considerations will reduce the oceanic absorption of CO2• The reduction will be the result of the warming of the surface waters and the reduction of their capacity for holding dissolved CO2, and of a further reduction in absorptive capacity from the gradual titration of the carbonate ion of oceanic water by CO2 from the atmosphere. Both processes speed the accumulation of CO2 in the atmosphere and augment the warming.
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Waite, Lowell E., Richard B. Koepnick y James R. Markello. "The Miocene World: A Brief Summary". En Cenozoic Isolated Carbonate Platforms—Focus Southeast Asia, 32–48. SEPM (Society for Sedimentary Geology), 2023. http://dx.doi.org/10.2110/sepmsp.114.03.
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This paper presents a brief synopsis of the Miocene Epoch, an important transitory chapter in the history of the Earth. It was during the Miocene that the major continents and oceans attained a “modern” configuration in terms of paleogeography and tectonics, oceanic ventilation and circulation, ocean chemistry, and faunal and floral assemblages. It also was during the Miocene that global climate fully transitioned into its current icehouse state, including marked growth of the Antarctic ice sheet and initiation of the Arctic ice cap. Long-term global cooling was controlled by a number of factors including tectonics, the large-scale changes in the distribution of flora, particularly the expansion of grasslands, and by fluctuating orbital parameters of the Earth. This global cooling trend was briefly interrupted by a short period of warming in the middle Miocene. Miocene sea-level changes consisted of a number of glacio-eustatic third-order (1–5 million year [m.y.] duration) cycles superposed upon three longer-term, second-order (5–20 m.y. duration) supercycles. Development of large-scale tropical carbonate systems in the Miocene was relegated to three main geographic regions: the circum-Caribbean, Mediterranean, and Indo-Pacific. In addition, a pronounced cool-water platform system developed along the southern margin of Australia. Miocene reefal buildups were dominated by tropical to subtropical framework assemblages consisting primarily of large scleractinian corals, encrusting red algae, and rhodoliths (free-living coralline red algae) that grew on platform margins and interiors or on isolated atolls. Miocene carbonates were deposited in a variety of oceanic and structural settings and constitute important petroleum reservoirs, particularly in Southeast Asia. Deep-water terrigenous clastic sediments of Miocene age are also important petroleum reservoirs in some regions. In addition, the Miocene interval contains numerous prolific petroleum source rocks, most composed of Type III (gas-prone) kerogen.
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"Chapter 4 The Oceanic Carbonate System and Calcium Carbonate Accumulation in Deep Sea Sediments". En Geochemistry of Sedimentary Carbonates, 133–77. Elsevier, 1990. http://dx.doi.org/10.1016/s0070-4571(08)70333-9.
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Bing, Saw Bing, Mu Ramkumar, Jyotsana Rai, JosÉ Antonio Gámez Vintaned, Grisel Jimenez, Syed Haroon Ali y Michael Pöppelreiter. "The Evolution of Carbonate Systems During the Oligocene–Miocene Transition: An Example of Subis Limestone, Malaysia". En Cenozoic Isolated Carbonate Platforms—Focus Southeast Asia, 164–78. SEPM (Society for Sedimentary Geology), 2023. http://dx.doi.org/10.2110/sepmsp.114.13.
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The Subis Platform is considered one of the very few outcrops in Malaysia which records remarkable changes in the growth history of a carbonate system. The Subis Platform is located near Batu Niah, Sarawak. Stratigraphically, the Subis Platform is named the Subis Limestone, a member of the Tangap Formation. This article discusses the older succession of the Subis Limestone at the Subis-2 well and the Hollystone Quarry. Both well and outcrop indicate a slightly older succession based on the occurrence of larger benthic foraminifera and calcareous nannofossils. The age of the Subis Limestone ranges from Oligocene to Miocene, based on the occurrence of the larger benthic foraminifera Miogypsinoides sp. (late Oligocene, Te4) and Miogypsina sp. (early Miocene, Te5), as well as on the calcareous nannofossils Sphenolithus capricornutus and Sphenolithus conicus (Te4). The boundary between the late Oligocene and the early Miocene coincides with a sharp change from foraminifera-dominated facies to coral-dominated facies, shown at the Hollystone Quarry. The Subis Limestone records a transgression event from mixed siliciclastic–carbonate (Subis-2 well) to clean biohermal carbonates as shown in the outcrops of the Subis quarries. Our findings on the Oligo–Miocene boundary were then compared with those from other carbonates around Southeast Asia. It is clear that coral reefs existed in Southeast Asia earlier than was first thought, by Oligocene times. The role of localized tectonic events, siliciclastic influx, oceanic mineralization, and Indonesian Throughflow are the main controls to determine the biota changes from foraminifera to coral-dominated facies.
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Dolman, Han. "DETERMINING ATMOSPHERIC AND OCEANIC CARBON DIOXIDE". En Carbon Dioxide through the Ages, 193–224. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780198869412.003.0009.
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Abstract We get acquainted with measurements of the concentration (mole fraction) of CO2 in the atmosphere. Charles David Keeling started the famous Mauna Loa series in 1958 that is now the iconic symbol of human impact on the climate. He made direct measurements of the mole fraction, rather than the indirect measurements obtained by chemical titration. He noticed that there was a small gradual increase per year in the baseline. Soon he related this to the impact of fossil fuel burning. In 1957 Roger Revelle and Hans Suess stated famously that ‘human beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.’ Bert Bolin subsequently showed that taking up CO2 by the surface ocean is one thing but bringing it down to the deep ocean quite another. Measuring carbon in the ocean is more difficult than in the atmosphere as it comes in three different forms, dissolved CO2, carbonate, and bicarbonate. The three are in intricate chemical equilibrium, which can shift depending on the availability of one or more of the components. This equilibrium forms the basis for the buffering capacity of the ocean. The US-based Japanese scientist Taro Takahashi did for ocean measurements what Keeling had done for the atmosphere—he developed a system to directly measure the concentration of CO2 in ocean surface waters. Today, observations in the atmosphere and ocean are coordinated by several large international programmes.
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Chang, Zhaoshan, Qihai Shu y Lawrence D. Meinert. "Chapter 6 Skarn Deposits of China". En Mineral Deposits of China, 189–234. Society of Economic Geologists, 2019. http://dx.doi.org/10.5382/sp.22.06.
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Abstract Skarn deposits are one of the most common deposit types in China. The 386 skarns summarized in this review contain ~8.9 million tonnes (Mt) Sn (87% of China’s Sn resources), 6.6 Mt W (71%), 42 Mt Cu (32%), 81 Mt Zn-Pb (25%), 5.4 Mt Mo (17%), 1,871 tonnes (t) Au (11%), 42,212 t Ag (10%), and ~8,500 Mt Fe ore (~9%; major source of high-grade Fe ore). Some of the largest Sn, W, Mo, and Zn-Pb skarns are world-class. The abundance of skarns in China is related to a unique tectonic evolution that resulted in extensive hydrous magmas and widespread belts of carbonate country rocks. The landmass of China is composed of multiple blocks, some with Archean basements, and oceanic terranes that have amalgamated and rifted apart several times. Subduction and collisional events generated abundant hydrous fertile magmas. The events include subduction along the Rodinian margins, closures of the Proto-Tethys, Paleo-Asian, Paleo-Tethys, and Neo-Tethys Oceans, and subduction of the Paleo-Pacific plate. Extensive carbonate platforms developed on the passive margins of the cratonic blocks during multiple periods from Neoarchean to Holocene also facilitated skarn formation. There are 231 Ca skarns replacing limestone, 15 Ca skarns replacing igneous rocks, siliciclastic sedimentary rocks, or metamorphic silicate rocks, 113 Ca-Mg skarns replacing dolomitic limestone or interlayered dolomite and limestone, and 28 Mg skarns replacing dolomite in China. The Ca and Ca-Mg skarns host all types of metals, as do Mg skarns, except for major Cu and W mineralization. Boron mineralization only occurs in Mg skarns. The skarns typically include a high-temperature prograde stage, iron oxide-rich higher-temperature retrograde stage, sulfide-rich lower-temperature retrograde stage, and a latest barren carbonate stage. The zoning of garnet/pyroxene ratios depends on the redox state of both the causative magma and the wall rocks. In an oxidized magma-reduced wall-rock skarn system, such as is typical of Cu skarns in China, the garnet/pyroxene ratio decreases, and garnet color becomes lighter away from the intrusion. In a reduced intrusion-reduced wall-rock skarn system, such as a cassiterite- and sulfide-rich Sn skarn, the skarn is dominated by pyroxene with minor to no garnet. Manganese-rich skarn minerals may be abundant in distal skarns. Metal associations and endowment are largely controlled by the magma redox state and degree of fractionation and, in general, can be grouped into four categories. Within each category there is spatial zonation. The first category of deposits is associated with reduced and highly fractionated magma. They comprise (1) greisen with Sn ± W in intrusions, grading outward to (2) Sn ± Cu ± Fe at the contact zone, and farther out to (3) Sn (distal) and Zn-Pb (more distal) in veins, mantos, and chimneys. The second category is associated with oxidized and poorly to moderately fractionated magma. Ores include minor porphyry-style Mo and/or porphyry-style Cu mineralization ± Cu skarns replacing xenoliths or roof pendants inside intrusions, zoned outward to major zones of Cu and/or Fe ± Au ± Mo mineralization at the contact with and in adjacent country rocks, and farther out to local Cu (distal) + Zn-Pb (more distal) in veins, mantos, and chimneys. Oxidized and highly fractionated magma is associated with porphyry Mo or greisen W inside an intrusion, outward to Mo and/or W ± Fe ± Cu skarns at the contact zone, and farther to Mo or W ± Cu in distal veins, mantos, and chimneys. The final category is associated with reduced and poorly to moderately fractionated magma. No major skarns of this type have been recognized in China, but outside China there are many examples of such intrusions related to Au-only skarns at the contact zone. Reduced Zn-Au skarns in China are inferred to be distal parts of such systems. Tungsten and Sn do not occur together as commonly as was previously thought. The distal part of a skarn ore system may transition to carbonate replacement deposits. Distal stratabound mantos and crosscutting veins/chimneys may contain not only Zn-Pb but also major Sn, W, Cu, Mo, and Au mineralization. The Zn-Pb mineralization may be part of either an oxidized system (e.g., Cu, Mo, Fe) or a reduced system (e.g., Sn). In China, distal Zn-Pb is more commonly related to reduced magmas. Gold and W may also be related to both oxidized and reduced magmas, although in China they are more typically related to oxidized magma. There are numerous examples of distal mantos/chimneys that continuously transition to proximal skarns at intrusion-wall-rock contact zones, and this relationship strongly supports the magmatic affiliation of such deposits and suggests that distal skarns/carbonate replacement deposits systems should be explored to find more proximal mineralization. Carbonate xenoliths or roof pendants may host the majority of mineralization in some deposits. In contact zones, skarns are better developed where the intrusion shape is complicated. The above two skarn positions imply that there may be multiple skarn bodies below drill interceptions of intrusive rocks. Many of the largest skarns for all commodities in China are related to small or subsurface intrusions (except for Sn skarns), have multiple mineralization centers, are young (<~160 Ma), and have the full system from causative intrusion(s) to distal skarns or carbonate replacement extensions discovered. Chinese skarn deposits fall in several age groups: ~830, ~480 to 420, ~383 to 371, ~324 to 314, ~263 to 210, ~200 to 83, ~80 to 72, and ~65 to 15 Ma. They are typically associated with convergent plate boundaries, mostly in subduction settings but also in collisional settings. Seven major skarn metallogenic belts are recognized based on skarn geographic location and geodynamic background. In subduction settings, skarns may form in a belt up to 4,000 km long and 1,000 km inland, with skarns continuously forming for up to 120 m.y., e.g., the eastern China belt. In most other belts, skarns form in 5- to 20-m.y. episodes similar to the situation in South America. In collisional settings, skarns may form up to 50 m.y. after an ocean closure, and the distance to the collisional/accretionary boundary may extend to ~150 km inland. The size of collision-related skarns may be as large as the largest skarns related to oceanic crust subduction. Older suture zones may be favorable sites for younger mineralization, for example, the Triassic Paleo-Tethys suture between the North and South China blocks for the younger and largest skarn cluster of the Middle-Lower Yangtze belt in the eastern China belt, and the Triassic sutures in southwestern China for Cretaceous to Tertiary mineralization.
Actas de conferencias sobre el tema "Oceanic carbonate system"
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Gray, William, Molly Trudgill, Nathaelle Bouttes, Guy Munhoven, Nathan Colle, Didier Roche, James Rae et al. "Glacial carbonate compensation in the Pacific Ocean constrained from paired oxygen and carbonate system reconstructions". En Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.16800.
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Maksimov, Danil, Alexey Pavlov y Sigbjørn Sangesland. "Drilling in Karstified Carbonates: Early Risk Detection Technique". En ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18263.
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Abstract Heterogeneous nature and complex rock properties of carbonate reservoirs makes the drilling process challenging. One of these challenges is uncontrolled mud loss. Caves or a system of cavities could be a high-risk zone for drilling as the mud losses cannot always be controlled by conventional methods, such as mud weight (MW) / equivalent mud weight (ECD) optimization, or by increasing concentration of lost circulation material (LCM) in the drilling mud. Seismic-based detection of such karstification objects is inefficient due to relatively small size, various shapes and low contrast environment. In this paper we, based on drilling data from the Barents sea, analyzed possible patterns in real-time drilling data corresponding to drilling through karstification objects. These patterns can serve as real-time indicators of zones with higher risk of karsts and can be used as an online tool for decision support while drilling in karstified carbonates.
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Al-Thani, Jassem A., Connor Izumi, Oguz Yigiterhan, Ebrahim Mohd A. S. Al-Ansari, Ponnumony Vethamony, Caesar Flonasca Sorino, Dan Anderson y James W. Murray. "Ocean Acidification and Carbonate System Geochemistry in the Arabian Gulf". En Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0030.
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Alkalinity (Alk) and (dissolved inorganic carbon) DIC were measured on high resolution seawater samples, collected on November 2018 and May 2019 at seven stations in the Exclusive Economic Zone (EEZ) of Qatar. Calculated surface PCO2 averaged 472 matm in 2018 and 447 matm in 2019. Thus, the Arabian Gulf is degassing CO2 at present and will not take up atmospheric CO2 until 2042. Ocean acidification is not yet an issue in the EEZ of Qatar. The elevated PCO2 values are due to CaCO3 formation. Normalized NAlk and NDIC were calculated to remove the impact of increasing salinity. NAlk and NDIC decrease corresponding to a CaCO3/OrgC removal ratio of 2/1. We calculated the nitrate corrected and salinity normalized tracer, Alk*. Values of Alk* were negative, and the change in Alk* relative to Hormuz (DAlk*) indicated that there has been an average decrease of Alk* of -130 mmol kg-1. This decrease is due to CaCO3 formation but previous studies found no evidence for coccolithophorids. One obvious possibility is that Alk removal is due to CaCO3 formation in coral reefs. However, recent study of the composition of particulate matter found that the average particulate Ca concentration was 3.6%, and was easily acid soluble (Yigiterhan et al., 2018). These results suggest that a significant amount of particulate CaCO3 is present in the water column. One hypothesis is that the particulate Ca comes from carbonate rich atmospheric dust. Using Al as a tracer for dust and the average Ca/Al ratio in Qatari dust can only explain about 3% of the particulate Ca. An alternative hypothesis is that particulate CaCO3 may form in the water column due to abiological CaCO3 formation, as proposed recently for the Red Sea (Wurgaft et al., 2016). Precipitation of CaCO3 may be induced by the large inputs of nucleation sites in the form of atmospheric dust.
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Gupta, Anuj. "Characterization of Matrix Wettability and Mass Transfer From Matrix to Fractures in Carbonate Reservoirs". En ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84172.
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This paper presents results of an experimental investigation, supported by numerical analysis, to characterize oil recovery from fractured carbonate reservoirs. Imbibition recovery of oil is measured as a function of time for samples with varying wettability and shape factors. One of the objectives of this study is to verify the validity of exponential transfer function for matrix-fracture systems with varying wettability and flow-boundary conditions. Another objective is to establish the possibility of quantitatively determining the wettability of a sample based on history-matching of cumulative imbibition recovery and recovery rate data. The productivity of most carbonate oil and gas reservoirs is closely tied to the natural or stimulated fracture system present in the reservoir. Further, the recovery from naturally fractured reservoirs, in presence of aquifer drive or waterflooding is closely tied to the wettability of the matrix. The approach presented in this paper offers means to evaluate how recovery factor in a fractured system can be affected by wettability. A detailed understanding of rock-fluid interactions and wettability alterations at the fracturing face should help design improved strategies for exploiting naturally fractured carbonate reservoirs.
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Han, Jinju, Youngjin Seo, Juhyun Kim, Sunlee Han y Youngsoo Lee. "Comparison of Oil Recovery and Carbonate Rock’s Properties Alterations by CO2 Miscible Flooding". En ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78723.
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This present study indicates experimental investigation about the impact of CO2 flooding on oil recovery and rock’s properties alteration in carbonate reservoir under the miscible condition. In order to compare the effect to initial pore characteristic, two type of carbonate rock was used; an Edward white represents homogeneous mainly consisted micropore, whereas an Indiana limestone represented heterogeneous mainly consisted macropore in this study. Under the miscible condition (9.65 MPa and 40°C), five pore volume of CO2 were injected into oil-wet carbonate rock, which was fully saturated with oil and connate water. After CO2 flooding, several analyses for each sample conducted to investigate oil recovery and rock properties change in porosity, permeability, and pore structure by chemical and physical reaction between CO2, water, and carbonate mineral before and after CO2 flooding by using core analysis, MICP, SEM, ICP, and X-ray CT techniques. From the results of oil recovery, it was more effective and larger in Edward white than in Indiana limestone. Because homogeneous characteristic with a large ratio of low permeable micropore in Edward white contributed to occur long reaction time between oil and CO2 for enough miscibility as well as to displace stably oil by CO2. Conversely, heterogeneous pore structure mainly consisted of high permeable conduit (macropore) in Indiana limestone has brought ineffective and low oil production. From the analysis of rock’s properties alteration, we found that, for the homogeneous sample, dissolution dominantly changed pore structure and became better flow path by improving permeability and reducing tortuosity. While plugging by precipitation of mineral particles was not critically affected rock’ properties, despite the sample mainly consisted small pores. In the case of the heterogeneous sample, both dissolution and precipitation critically affected change of rock’s properties and pore structure. In particular, superior precipitation in complex pore network seriously damaged flow path and change of rock’s properties. The largest porosity change markedly appeared in inlet section because of exposing rock surface from fresh CO2 during a long time. In conclusion, it shows that CO2 miscible flooding in carbonate reservoirs significantly affected to alteration of rock’s properties such as porosity, permeability, tortuosity, and pore connectivity, in particular in heterogeneous system compared with in homogeneous system. These experimental results can be useful to characterize carbonate rock as well as to study rock properties alteration on CO2 EOR and CCS processes.
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Lagkaditi, Lydia, Ashok Srivastava y Anuj Gupta. "Geology-Based Reservoir Model Building for Carbonate Reservoirs". En ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11328.
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Environment in which carbonate reservoir rocks are deposited was studied by visiting and collecting rock samples from a carbonate reservoir analog located at Jabal Fuwairit in the Northeastern coast of Qatar. The primary objective of this study is to develop methods to characterize carbonate reservoirs. The experimental procedure included collecting samples based on geology, mapping the location and altitudes of the samples using a high-resolution Global Positioning System (GPS) with an altimeter, permeability measurements at selected locations, conducting petrophysical measurements on the samples, Conventional and Micro-X-ray Computed Tomography Scanning (CT Scanning), Scanning Electron Microscopy (SEM), X-ray Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM) imaging. It is observed that the permeability measurements show an alternating pattern as a function of height above sea level. The cyclicity is probably representative of repeating sequences of sea level changes over geological time. CT Scanner and Micro-CT Scanner measurements were employed to obtain vital information about the flow pathways in the rock, thus assisting in calculating the porosity to compare with values measured in the lab. SEM results gave direct visualization of the pore network and information about grain size (500 microns) and intergranular porosity, mineralogy, compared with the EDS results, and lithotype. EDS results showed that reservoir rocks directly exposed to environment had significant alteration due to weathering. However, it is encouraging to learn that samples even few inches away from the surface had minimal environmental influence.
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Beemer, Ryan D., Alexandre N. Bandini-Maeder, Jeremy Shaw, Ulysse Lebrec y Mark J. Cassidy. "The Granular Structure of Two Marine Carbonate Sediments". En ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77087.
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Calcareous sediments are prominent throughout the low-latitudinal offshore environment and have been known to be problematic for offshore foundation systems. These fascinating soils consist largely of the skeletal remains of single-celled marine organisms (plankton and zooplankton) and can be as geologically complex as their onshore siliceous counter parts. To enable an adequate understanding of their characteristics, in particular, their intra-granular micro-structure, it is important that geotechnical engineers do not forget about the multifaceted biological origins of these calcareous sediments and the different geological processes that created them. In this paper, the 3D models of soils grains generated from micro-computed tomography scans, scanning electeron microscope images, and optical microscope images of two calcareous sediments from two different depositional environments are presented and their geotechnical implications discussed. One is a coastal bioclastic sediment from Perth, Western Australia that is geologically similar to carbonate sediments typically used in micro-mechanics and particle crushing studies in the literature. The other is a hemipelagic sediment from a region of the North West Shelf of Australia that has historically been geotechnically problematic for engineers. The results show there is a marked difference between coastal bioclastic and hemipelagic sediments in terms of geological context and the associated particle micro-structures. This brings into question whether a coastal bioclastic calcareous sediment is a good micro-mechanical substitute for a hemipelagic one.
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Boukpeti, Nathalie, Barry Lehane y J. Antonio H. Carraro. "Strain Accumulation Procedure During Staged Cyclic Loading of Carbonate Sediments". En ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23692.
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Design of offshore foundation systems requires assessment of the effects of cyclic loading on the soil strength. This paper investigates the applicability of the strain accumulation procedure, which is used to assess the effects of wave loading on the soil strength. Staged undrained cyclic simple shear tests were conducted on a carbonate sediment from the North West shelf of Australia, with varying shear stress amplitude in each stage. The shear strain mobilised at the end of the staged tests is compared with the value predicted by the strain accumulation procedure, using shear strain contours constructed from the results of single amplitude undrained cyclic simple shear tests. It was found that the strain accumulation procedure gives adequate prediction for normalised cyclic shear stress less or equal to 0.3, but largely underestimates the cyclic shear strain for normalised cyclic shear stress greater than 0.3 (the cyclic shear stress being normalised by the effective vertical stress at the end of consolidation).
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Li, Mu, Lufeng Zhang y Minghui Li. "Study on Acid Fracturing Technology for Carbonate Reservoirs in Ordos Basin". En ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19296.
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Abstract Acid fracturing, a key stimulation technology, has been widely applied in carbonate formations, which have the complex reservoir space and natural fracture. However, the conventional acid fracturing technology has limitations in target reservoir due to serious acid leakage and rapid acid-rock reaction speed. Therefore, a deep-penetration acid fracturing technology was proposed to enhance the stimulation effect. The reservoir basic physical properties, such as permeability and porosity, microstructure characteristic of pore throats, mineral composition, and rock mechanics characteristics, were systemically investigated by a series of laboratory experiments. The acid system was also optimized by evaluating rheological properties and residual acid damage. Furthermore, the most important two parameters of acid fracturing, conductivity and effective acid-etched fracture length, were obtained by numerical simulation with commercial software Fracpro PT. Based on the laboratory studies, the acid fracturing technology was applied in the field, and the production of well increased by 1.7 times after stimulation.
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Sarma, Hemanta K. y Yi Zhang. "Brine Chemistry Effects in Waterflood and CO2 Injection in Carbonate Reservoirs". En ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23247.
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It has been reported that the waterflood performance in carbonate reservoirs could be significantly ameliorated by tuning the injected brine salinity and ionic composition. Also, it is noted that the brine salinity affects the CO2 injection process. This study looked into such possible effects of brine chemistry on waterflood and CO2 injection for typical UAE carbonate reservoir conditions of high temperature and pressure (T = 120°C and P = 20.68MPa). Effects on waterflood performance were investigated experimentally by a series of flooding tests at temperatures of 70°C and 120°C. In addition, an imbibition test was conducted at 70°C, followed by wettability monitoring tests at 90°C to investigate the impact of brine salinity variations and ionic compositions on waterflood performance. The impact of brine salinity on CO2-brine system properties including CO2 solubility in brine, interfacial tension between CO2 and CO2-saturated brine, and density and viscosity of CO2-saturated brine were evaluated through correlation-based studies in conjunction with some experimental data. A mathematical pore-scale model was developed to assess the brine salinity effect on water-isolated oil recovery by CO2 diffusion through water barrier. This study led to the following findings: (1) Incremental oil recovery could be obtained by either reducing salinity or increasing sulfate concentration of the tertiary injected brine at both 70°C and 120°C. However, the incremental recovery was more remarkable at the higher temperature of 120°C. (2) At 70°C, lowering the water salinity is more effective than raising the sulfate concentration in injected water in terms of incremental oil recovery. It also exhibited a similar potential for increased oil recovery at 120°C. (3) Wettability monitoring tests showed that water-wetness of carbonate rock studied could be increased by either reducing the water salinity or increasing sulfate concentration of the surrounding water. This is consistent with the imbibition test, in which wettability alteration towards more water-wetness by low salinity water was noted. (4) Under typical UAE reservoir conditions, reducing the brine salinity could significantly enhance CO2 dissolution in brine, consequently inducing significant variation to the CO2-brine system properties. This would undoubtedly impact CO2 injection performance. (5) Under typical UAE reservoir conditions, the capacity and rate of CO2 diffusion through water barrier to oil phase could be significantly reinforced by lowering the brine salinity of the water barrier.
Informes sobre el tema "Oceanic carbonate system"
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Wimart-Rousseau, Cathy, Marine Fourrier y Fiedler Björn. Development of BGCArgo data quality validation based on an integrative multiplatform approach. EuroSea, 2022. http://dx.doi.org/10.3289/eurosea_d7.2.
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This report presents the results of Task 7.3 on “Development of BGC-Argo data quality validation based on an integrative multiplatform approach”. Observing changes in ocean conditions on the spatiotemporal scales necessary to constrain carbon uptake is a challenge. Defined as an Essential Ocean Variable (EOV) by the Global Ocean Observing System (GOOS, e.g., Tanhua et al., 2019), pH is relevant to assess numerous crucial questions regarding the oceanic evolution in response to the current global changes. However, the large spatiotemporal variability of this carbonate system parameter requires sustained observations to decipher trends and punctual events. Within this scope, numerous pH sensors suitable for deployments both on autonomous observing tools and fixed stations have been developed. Nevertheless, as interpreting changes relies on accurate data, and because offsets or drifts in pH data might appear in response to changes in the sensor k0 constant, a consistent and rigorous correction procedure to quality-control and process the data has been implemented. This report presents the application of this method to pH data acquired by BGC-Argo floats launched in the Tropical Atlantic area. (EuroSea Deliverable, D7.2)
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Fourrier, Marine. Integration of in situ and satellite multi-platform data (estimation of carbon flux for trop. Atlantic). EuroSea, 2023. http://dx.doi.org/10.3289/eurosea_d7.6.
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This report presents the results of task 7.3 on “Quantification of improvements in carbon flux data for the tropical Atlantic based on the multi-platform and neural network approach”. To better constrain changes in the ocean’s capture and sequestration of CO2 emitted by human activities, in situ measurements are needed. Tropical regions are considered to be mostly sources of CO2 to the atmosphere due to specific circulation features, with large interannual variability mainly controlled by physical drivers (Padin et al., 2010). The tropical Atlantic is the second largest source, after the tropical Pacific, of CO2 to the atmosphere (Landschützer et al., 2014). However, it is not a homogeneous zone, as it is affected by many physical and biogeochemical processes that vary on many time scales and affect surrounding areas (Foltz et al., 2019). The Tropical Atlantic Observing System (TAOS) has progressed substantially over the past two decades. Still, many challenges and uncertainties remain to require further studies into the area’s role in terms of carbon fluxes (Foltz et al., 2019). Monitoring and sustained observations of surface oceanic CO2 are critical for understanding the fate of CO2 as it penetrates the ocean and during its sequestration at depth. This deliverable relies on different observing platforms deployed specifically as part of the EuroSea project (a Saildrone, and 5 pH-equipped BGC-Argo floats) as well as on the platforms as part of the TAOS (CO2-equipped moorings, cruises, models, and data products). It also builds on the work done in D7.1 and D7.2 on the deployment and quality control of pH-equipped BGC-Argo floats and Saildrone data. Indeed, high-quality homogeneously calibrated carbonate variable measurements are mandatory to be able to compute air-sea CO2 fluxes at a basin scale from multiple observing platforms. (EuroSea Deliverable, D7.6)
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Schwinger, Jörg. Report on modifications of ocean carbon cycle feedbacks under ocean alkalinization. OceanNETs, junio de 2022. http://dx.doi.org/10.3289/oceannets_d4.2.
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Ocean Alkalinization deliberately modifies the chemistry of the surface ocean to enhance the uptake of atmospheric CO2. Here we quantify, using idealized Earth system model (ESM) simulations, changes in carbon cycle feedbacks and in the seasonal cycle of the surface ocean carbonate system due to ocean alkalinization. We find that both, carbon-concentration and carbon climate feedback, are enhanced due to the increased sensitivity of the carbonate system to changes in atmospheric CO2 and changes in temperature. While the temperature effect, which decreases ocean carbon uptake, remains small in our model, the carbon concentration feedback enhances the uptake of carbon due to alkalinization by more than 20%. The seasonal cycle of air-sea CO2 fluxes is strongly enhanced due to an increased buffer capacity in an alkalinized ocean. This is independent of the seasonal cycle of pCO2, which is only slightly enhanced. The most significant change in the seasonality of the surface ocean carbonate system is an increased seasonal cycle of the aragonite saturation state, which has the potential to adversely affect ecosystem health.
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Seifert, Miriam, Claudia Hinrichs, Judith Hauck y Christoph Völker. New / improved model parametrizations for responses in phytoplankton growth and calcification to changes in alkalinity implemented. OceanNets, marzo de 2023. http://dx.doi.org/10.3289/oceannets_d4.5.
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Global biogeochemical ocean models that are currently in place to investigate alkalinity enhancement at a global scale do usually not consider the effects of a changing carbonate system on phytoplankton. We introduce new and modified parameterizations of phytoplankton carbonate systems sensitivities into the biogeochemistry model REcoM. We then compare phytoplankton biomass and net primary production at different atmospheric CO2 concentrations to results from other deliverables (D5.3, 5.6, 5.7) based on experiments and models. The resilience of phytoplankton biomass towards low CO2 concentrations in our model compares well with the results of mesocosm experiments. Or model results differ in the phytoplankton responses compared to the results of a 1D biogeochemical model that employs similar parameterizations regarding the effects on calcifying phytoplankton and total net primary production, which we explain primarily with differences in the spatial scales and phytoplankton communities investigated.
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Scanlan, E. J., M. Leybourne, D. Layton-Matthews, A. Voinot y N. van Wagoner. Alkaline magmatism in the Selwyn Basin, Yukon: relationship to SEDEX mineralization. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328994.
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Several sedimentary exhalative (SEDEX) deposits have alkaline magmatism that is temporally and spatially associated to mineralization. This report outlines interim data from a study of potential linkages between magmatism and SEDEX mineralization in the Selwyn Basin, Yukon. This region is an ideal study site due to the close spatial and temporal relationships between SEDEX deposits and magmatism, particularly in the MacMillan Pass, where volcanic rocks have been drilled with mineralization at the Boundary deposit. Alkaline volcanic samples were analysed from the Anvil District, MacMillan Pass, Keno-Mayo and the Misty Creek Embayment in the Selwyn Basin to characterise volcanism and examine the relationship to mineralization. Textural and field relationships indicate a volatile-rich explosive eruptive volcanic system in the MacMillan Pass region in comparison to the Anvil District, which is typically effusive in nature. High proportions of calcite and ankerite in comparison to other minerals are present in the MacMillan system. Cathodoluminescence imaging reveals zoning and carbonate that displays different luminescent colours within the same sample, likely indicating multiple generations of carbonate precipitation. Barium contents are enriched in volcanic rocks throughout the Selwyn Basin, which is predominately hosted by hyalophane with rare barite and barytocalcite. Thallium is positively correlated with Ba, Rb, Cs, Mo, As, Sb and the calcite-chlorite-pyrite index and is negatively correlated with Cu. Anvil District samples display a trend towards depleted mid-ocean ridge mantle on a plot of Ce/Tl versus Th/Rb. Hydrothermal alteration has likely led to the removal of Tl from volcanic rocks in the region. Ongoing research involves: i) the analysis of Sr, Nd, Pb and Tl isotopes of volcanic samples; ii) differentiating magmatic from hydrothermal carbonate using O, C and Sr isotopes; iii) examining sources of Ba in the Selwyn Basin; iv) and constraining age relationships through U-Th-Pb geochronology.
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Riebesell, Ulf. Comprehensive data set on ecological and biogeochemical responses of a low latitude oligotrophic ocean system to a gradient of alkalinization intensities. OceanNets, agosto de 2022. http://dx.doi.org/10.3289/oceannets_d5.4.
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The potential biogeochemical and ecological impacts of ocean alkalinity enhancement were tested in a 5-weeks mesocosm experiment conducted in the subtropical, oligotrophic waters off Gran Canaria in September/October 2021. In the nine mesocosms, each with a volume of about 10 m3 inhabiting a natural plankton community, alkalinity enhancement was achieved through addition of a mix of sodium bicarbonate and sodium carbonate, simulating CO2-equilibrated alkalinization in a gradient from control up to twice the natural alkalinity. The response of the enclosed plankton community to the alkalinity addition was monitored in over 50 parameters which were sampled or measured in situ daily or every second day. In addition to the mesocosm experiment, a series of side experiments were conducted, focusing on individual aspects of mineral dissolution, secondary precipitation and biological responses at the primary producer level. This campaign, in which 47 scientists from 6 nations participated, generated the most comprehensive data set collected so far on the ecological and biogeochemical impacts of ocean alkalinity enhancement.