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Oceanography

Oceanography encompasses many diverse disciplines, relating to the physical, chemical and biological processes which occur in the Earth’s oceans. Stable isotope analysis provides a powerful means to trace these processes, both modern and ancient; palaeoceangraphy uses oxygen stable isotope signatures of materials preserved in ice cores or sediments to elucidate the history of sea-surface or deep sea temperatures. Stable isotopes of oxygen and hydrogen can also reveal the hydrology of oceanic waters, tracing the movement and circulation of waters, evaporitic processes, and meteorological influences on local, regional or global scales.

Nutrient cycling and ecology of the world’s oceans is also of interest; carbon, nitrogen and sulfur stable isotopes are powerful tools which may be deployed to trace algal activity, elucidate food chain structures within surface or benthic communities, and trace fluxes of nutrients throughout the seasons. Stable isotope analysis is particularly useful for exploring the unusual frontiers of deep hydrothermal systems, where unusual chemosynthetic organisms are the lynchpins of the communities which thrive under those extreme conditions.

Oceanography publications using our instrumentation

Our customers use our instruments to do some amazing research in the oceanography application field. To show you how they perform their research and how they use our IRMS instruments, we have collected a range of peer-reviewed publications which cite our products. You can find the citations below and then follow the links to the publishing journal should you wish to download the publication.

If you would like to investigate our available citations in more detail, or email the citation list to yourself or your colleagues then take a look at our full citation database.

83 results:

Sources of δ15N variability in sinking particulate nitrogen in the Cariaco Basin, Venezuela
Deep-Sea Research Part II: Topical Studies in Oceanography (2013)
Enrique Montes, Robert Thunell, Frank E. Muller-Karger, Laura Lorenzoni, Eric Tappa, Luis Troccoli, Yrene Astor, Ramón Varela

Ten years of monthly observations of the δ15N of sinking particulate nitrogen (δ15N-PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)-1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasonal and interannual variability in regional surface ocean processes. During the upwelling period of the southern Caribbean Sea (February-April), the δ15N-PN is similar to that of the thermocline nitrate (~3.5‰). This nitrate is imported into the Cariaco Basin with Subtropical Underwater (SUW), which wells up near the coast. Thus, particles generated by phytoplankton photosynthesis during this productive period bear a sub-tropical North Atlantic isotopic imprint of N2 fixation (low compared to the global average of nitrate δ15N≈5‰). During the non-upwelling period when surface waters are stratified (September-November), the δ15N-PN is also 3.5-4.0‰, and reflects a mixture of local N2 fixation within the mixed layer, inputs of terrigenous organic matter and SUW nitrate consumption by phytoplankton below the mixed layer, which most likely exerts the strongest control on the δ15N-PN signal during this time. In the transition periods of May-July and December-January, the δ15N-PN increases to 4.5-6.5‰. This coincides with maxima of continental material fluxes (terrestrial PON δ15N is >6‰) into the Cariaco Basin. The δ15N signal in the sediments of the Cariaco Basin thus provides information about the relative strength of the local coastal upwelling, the relative input of continental material via river runoff, and local N2 fixation. The findings contribute to interpretations of the basin's paleoclimatic nitrogen cycle variations based on observations of the sedimentary δ15N record at this location. © 2013 .
Tags: nitrogen , ocea , elem

An equilibrator system to measure dissolved oxygen and its isotopes
Journal of Atmospheric and Oceanic Technology (2013)
Lauren Elmegreen Rafelski, Bill Paplawsky, Ralph F. Keeling

AbstractAn equilibrator is presented that is designed to have a sufficient equilibration time even for insoluble gases, and to minimize artifacts associated with not equilibrating to the total gas tension. A gas tension device was used to balance the pressure inside the equilibrator with the total gas tension. The equilibrator has an e-folding time of 7.36 ± 0.74 min for oxygen and oxygen isotopes, allowing changes on hourly time scales to be easily resolved. The equilibrator delivers “equilibrated” air at a flow rate of 3 mL min-1 to an isotope ratio mass spectrometer. The high gas sampling flow rate would allow the equilibrator to be interfaced with many potential devices, but further development may be required for use at sea. This system was tested at the Scripps Institution of Oceanography pier, in La Jolla, California. A mathematical model validated with performance tests was used to assess the sensitivity of the equilibrated air composition to headspace pressure and makeup gas composition. Paramete...

Environmental controls on coral skeletal ??13C in the northern South China Sea
Journal of Geophysical Research: Biogeosciences (2013)
Wenfeng Deng, Gangjian Wei, Luhua Xie, Kefu Yu

n this paper, we investigate the relationship between seasonal climatic and environmental variables, and the skeletal δ13C of modern and mid-Holocene Porites lutea corals from the southern coast of Hainan Island in the northern South China Sea. No significant correlations were observed between δ13C in the modern coral and solar insolation or sea surface temperature. However, seasonal variability of δ13C in the modern coral covaries with rainfall on Hainan Island. Furthermore, the seasonal variations of δ13C in both the modern and mid-Holocene coral are synchronous with those of the coral Δδ18O, which is a proxy for seawater δ18O and, in turn, largely controlled by local rainfall. These observations suggest that coral δ13C variations are closely associated with rainfall in this region. Given that river runoff contains dissolved inorganic carbon (DIC) with a negative δ13C, we suggest that periods of high rainfall on Hainan Island deliver increased amounts of 13C-depleted DIC to coastal seawater, resulting in an enhanced negative δ13C in the corals. Our findings, together with previous studies, appear to demonstrate that in coastal environments, coral skeletal δ13C levels are controlled mainly by terrestrial carbon input and are significantly influenced by terrestrial river runoff. Consequently, the geochemical interpretation of coral δ13C records may differ between coastal areas and offshore areas or the open ocean.
Tags: carbon , oxygen , geol , ocea , mulitcarb

D/H equilibrium fractionation between H2O and H2 as a function of the salinity of aqueous solutions
Chemical Geology (2012)
François Martineau, François Fourel, Anne-Marie Bodergat, Christophe Lécuyer

Hydrogen isotope fractionation between H2O and H2 has been investigated at 313 K for sodium chloride solutions with salinities (S) ranging from 0 to 265 g.L− 1. In the presence of a Pt catalyst, time needed to reach hydrogen isotope equilibrium between H2O and H2 is close to 3 h (t1/2 ≈ 30 min), independently on the salinity of the aqueous solution. Hydrogen isotope fractionation between H2O and H2 increases with increasing molality (m) for a NaCl-like (sea salt) solution according to the following linear function: αH2O-H2(sea salt) = 3.387(± 8.4 × 10− 5) + 3.4 × 10− 3(± 5 × 10− 5)m (R2 = 0.997). The hydrogen isotope analysis of seawater samples with a salinity of 35 g.L− 1 requires minor corrections of − 2 ± 0.5‰ (V-SMOW) whilst δD values are overestimated by 5 ± 0.5‰ to 10 ± 0.5‰ in the case of highly saline natural waters (100 < S < 265 g.L− 1). In combination to previously published salinity-dependent fractionation factors between CO2 and H2O (Lécuyer et al., 2009), corrections of both hydrogen and oxygen isotope ratios must be taken into account during the analysis by equilibration techniques of waters sampled from salt marshes, hypersaline lakes and lagoons, or hydrothermal brines.

Impact of the Middle Jurassic diversification of Watznaueria (coccolith-bearing algae) on the carbon cycle and ?? 13C of bulk marine carbonates
Global and Planetary Change (2012)
Baptiste Such??ras-Marx, Abel Guihou, Fabienne Giraud, Christophe L??cuyer, Pascal Allemand, Bernard Pittet, Emanuela Mattioli

During the Mid Mesozoic Revolution, thought to have started 200Ma ago (Late Triassic), the production of calcium carbonate in the ocean shifted from platform and epicontinental seas to the open ocean, concurrently with the diversification of coccolithophorids. In this regard, the radiation of the coccolith genus Watznaueria during the Middle Jurassic is thought to represent one of the most important steps of this diversification. Nevertheless, the timing of this diversification remains poorly constrained, and its possible impact on global carbon budgets remains unclear. In this study, we present new records of nannofossil fluxes and carbon stable isotope composition from sedimentary deposits of Lower Bajocian age from the Cabo Mondego (Portugal) reference section to further address the possible impact of this diversification on the Middle Jurassic global carbon cycle. Our results show that calcareous nannofossil fluxes increase markedly from the upper part of the Aalenian to the Early Bajocian, coinciding with a 0.75??? positive shift in carbon isotope compositions of bulk carbonate. Reconstructions of mass accumulation rates indicate that nannofossil fluxes increased by two orders of magnitude (from 10 9 to 10 11nannofossils/m 2/yr) during the corresponding time interval, mainly related to the rise of Watznaueria genus, whose relative abundance jumped from 2% to 20% of the total rock composition. The calculated amount of carbon derived from calcareous nannofossils deposited in the Early Bajocian seas was, however, 10 to 20 times lower than current levels. Mass balance calculations indicate that the increase of nannofossil flux throughout the studied interval was most likely not the main cause of the accompanying isotopic perturbation, suggesting a limited role of the Early Bajocian diversification on the global carbon cycle. Our results show that while the diversification of Watznaueria throughout the Bajocian caused a major increase in the flux of pelagic carbonate to the deep ocean, it was most likely quantitatively insufficient to have a large impact on the global biogeochemistry of the oceans. ?? 2012 Elsevier B.V..
Tags: carbon , geol , ocea , clim , mulitcarb

Stable carbon and oxygen isotope compositions of invertebrate carbonate shells and the reconstruction of paleotemperatures and paleosalinities-A case study of the early Pleistocene of Rhodes, Greece
Palaeogeography, Palaeoclimatology, Palaeoecology (2012)
Christophe Lécuyer, Valérie Daux, Pierre Moissette, Jean Jacques Cornée, Frédéric Quillévéré, Efterpi Koskeridou, François Fourel, François Martineau, Bruno Reynard

The coastal sediments of Rhodes in the eastern Mediterranean have recorded transgression-regression cycles that took place during the early Pleistocene. The sedimentary deposits from the Kritika Member of the Rhodes Formation consist in conglomerates, sandstones, siltstones and clays deposited in brackish to shallow marine environments. Faunal associations are dominated by molluscs and reveal rapid ecological changes. Carbon and oxygen isotope ratios of aquatic skeletal carbonates show that these ecological changes were most likely driven by large salinity changes while water temperature remained rather constant at about 22.0 ± 1.5 °C. The tectonic activity of the island rather than glacio-eustatic variations of climatic origin is advocated to be responsible for the ecological and salinity changes and sea-level variations recorded in the sedimentary sequence. © 2012 Elsevier B.V.
Tags: carbon , oxygen , geol , ocea , clim , mulitcarb

Foraminifer isotope study of the Pleistocene Labrador Sea, northwest North Atlantic (IODP Sites 1302/03 and 1305), with emphasis on paleoceanographical differences between its "inner" and "outer" basins
Marine Geology (2011)
Claude Hillaire-Marcel, Anne De Vernal, Jennifer McKay

Cores raised during IODP Expedition 303 off southern Greenland (Eirik Ridge site 1305) and off the Labrador Coast (Orphan Knoll site 1302/1303) were analyzed to establish an isotope stratigraphy, respectively for the "inner" and "outer" basins of the Labrador Sea (LS). These isotopic data also provide information on the Atlantic Meridional Overturning Circulation (AMOC), notably with regard to the intensity of the Western Boundary Under Current (WBUC), which is tightly controlled by the production of Denmark Strait Overflow Water (DSOW), and the production of Labrador Sea Water (LSW) in the inner basin through winter cooling and convection. The upper 184m of sediment at Eirik Ridge spans marine isotope stages (MIS) 32 to 1. At this site, two distinct regimes are observed: prior to MIS 20, the isotopic record resembles that of the open North Atlantic records of the interval, whereas a more site-specific pattern is observed afterwards. This later pattern was characterized by i) high DSOW production rates and strong WBUC during interglacial stages, as indicated by sedimentation rates, ii) large amplitude ??18O-shifts from glacial stages to interglacial stages (>2.5%) and iii) an overall range of ??18O-values significantly more positive than before. At Orphan Knoll, the 105m record spans approximately 800ka and provides direct information on linkages between the northeastern sector of the Laurentide Ice Sheet and the North Atlantic. At this site, a shift towards larger amplitude glacial/interglacial ranges of ??18O-values occurred after MIS 13, although isotopic records bear a typical North Atlantic signature, particularly during MIS 5, in contradiction to those of Eirik Ridge, where substages 5a to 5c are barely recognized. Closer examination of ??18O-records in planktic and benthic foraminifera demonstrates the presence of distinct deep-water masses in the inner vs. outer LS basins during MIS 11 and more particularly MIS 5e. Data confirm that the modern AMOC, with LSW formation, seems mostly exclusive to the present interglacial, and also suggest some specificity of each interglacial with respect to the production rate of DSOW and the AMOC, in general. ?? 2010 Elsevier B.V.
Tags: carbon , oxygen , geol , ocea , clim , mulitcarb

Micropowder collecting technique for stable isotope analysis of carbonates
Rapid Communications in Mass Spectrometry (2011)
Saburo Sakai, Tsuyoshi Kodan

Micromilling is a conventional technique used in the analysis of the isotopic composition of geological materials, which improves the spatial resolution of sample collection for analysis. However, a problem still remains concerning the recovery ratio of the milled sample. We constructed a simple apparatus consisting of a vacuum pump, a sintered metal filter, electrically conductive rubber stopper and a stainless steel tube for transferring the milled powder into a reaction vial. In our preliminary experiments on carbonate powder, we achieved a rapid recovery of 5 to 100 µg of carbonate with a high recovery ratio (>90%). This technique shortens the sample preparation time, improves the recovery ratio, and homogenizes the sample quantity, which, in turn, improves the analytical reproducibility.
Tags: carbon , oxygen , geol , ocea , clim , mulitcarb

Oxygen isotope fractionation between apatite-bound carbonate and water determined from controlled experiments with synthetic apatites precipitated at 10-37 ??C
Geochimica et Cosmochimica Acta (2010)
Christophe Lecuyer, Vincent Balter, Fran??ois Martineau, Fran??ois Fourel, Aur??lien Bernard, Romain Amiot, V??ronique Gardien, Olga Otero, Serge Legendre, G??rard Panczer, Laurent Simon, Rossana Martini

The oxygen isotope fractionation between the structural carbonate of inorganically precipitated hydroxyapatite (HAP) and water was determined in the range 10-37 ??C. Values of 1000 ln ??(CO3 2 - s(-) H2 O) are linearly correlated with inverse temperature (K) according to the following equation: 1000 ln ??(CO3 2 - s(-) H2 O) = 25.19 (??0.53)??T-1 - 56.47 (??1.81) (R2 = 0.998). This fractionation equation has a slightly steeper slope than those already established between calcite and water (O'Neil et al., 1969; Kim and O'Neil, 1997) even though measured fractionations are of comparable amplitude in the temperature range of these experimental studies. It is consequently observed that the oxygen isotope fractionation between apatite carbonate and phosphate increases from about 7.5??? up to 9.1??? with decreasing temperature from 37 ??C to 10 ??C. A compilation of ??18O values of both phosphate and carbonate from modern mammal teeth and bones confirms that both variables are linearly correlated, despite a significant scattering up to 3.5???, with a slope close to 1 and an intercept corresponding to a 1000 ln ??(CO3 2 - s(-) PO4 3 -) value of 8.1???. This apparent fractionation factor is slightly higher or close to the fractionation factor expected to be in the range 7-8??? at the body temperature of mammals. ?? 2009 Elsevier Ltd. All rights reserved.
Tags: oxygen , geol , ocea , clim , mulitcarb

An improved inlet for precisely measuring the atmospheric Ar / N 2 ratio
Atmospheric Chemistry and Physics (2006)
T W Blaine, R F Keeling, W J Paplawsky

The atmosphericAr/N2 ratio is expected to be use- ful as a tracer of air-sea heat exchange, but this application has been hindered in part due to sampling artifacts. Here we show that the variability in δ(Ar/N2) due to thermal fraction- ation at the inlet can be on the order of 40–80 per meg, and we introduce the use of an aspirated solar shield that success- fully minimizes such fractionation. The data collected using this new inlet have a mean diurnal cycle of 1.0 per meg or less, suggesting that any residual thermal fractionation effect is reduced to this level
Tags: geol , ocea