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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:

Influence of environmental gradients on C and N stable isotope ratios in coral reef biota of the Red Sea, Saudi Arabia
Journal of Sea Research (2014)
Benjamin Kürten, Ali M. Al-Aidaroos, Ulrich Struck, Hisham Sulaiman Khomayis, Waleed Yousef Gharbawi, Ulrich Sommer

The Red Sea features a natural environmental gradient characterized by increasing water temperature, nutrient and chlorophyll a concentrations from North to South. The aim of this study was to assess the relationships between ecohydrography, particulate organic matter (POM) and coral reef biota that are poorly understood by means of carbon (δ13C) and nitrogen (δ15N) stable isotopes. Herbivorous, planktivorous and carnivorous fishes, zooplankton, soft corals (Alcyonidae), and bivalves (Tridacna squamosa) were a priori defined as biota guilds. Environmental samples (nutrients, chlorophyll a), oceanographic data (salinity, temperature), POM and biota were collected at eight coral reefs between 28°31' N and 16°31' N. Isotopic niches of guilds separated in δ13C and δ15N isotopic niche spaces and were significantly correlated with environmental factors at latitudinal scale. Dietary end member contributions were estimated using the Bayesian isotope mixing model SIAR. POM and zooplankton 15N enrichment suggested influences by urban run-off in the industrialized central region of the Red Sea. Both δ15N and their relative trophic positions (RTPs) tend to increase southwards, but urban runoff offsets the natural environmental gradient in the central region of the Red Sea toward higher δ15N and RTPs. The present study reveals that consumer δ13C and δ15N in Red Sea coral reefs are influenced primarily by the latitudinal environmental gradient and localized urban runoff. This study illustrates the importance of ecohydrography when interpreting trophic relationships from stable isotopes in Red Sea coral reefs. © 2013 Elsevier B.V.
Tags: carbon , nitrogen , ecol , ocea , elem

Multiproxy reconstruction for Kuroshio responses to northern hemispheric oceanic climate and the Asian Monsoon since Marine Isotope Stage 5.1 (∼88 ka)
Climate of the Past (2014)
X. Shi, Y. Wu, J. Zou, Y. Liu, S. Ge, M. Zhao, J. Liu, A. Zhu, X. Meng, Z. Yao, Y. Han

The Kuroshio, a western boundary current in the northwestern Pacific, plays a key role in regulating ocean and climate in East Asia. The evolution of the Kuroshio and its branches has been the focus of paleoceanographic studies. In this study, we applied a multiproxy (grain size, planktonic foraminiferal species, δ18O, alkenone sea surface temperature (SST) and salinity) reconstruction from sediment core CSH1, which is located at the main axis of the Tsushima Warm Current, a branch of the Kuroshio, in the northern Okinawa Trough (OT). This study, extended the paleoceanographic record of the Kuroshio to Marine Isotope Stage (MIS) 5.1 (∼88 ka) from the far northern site in the OT. Planktonic foraminiferal species identified from this core contain warm-water species related to the Kuroshio and cold-water species related to subarctic water mass. The relative abundances of the warm-water species are high during MIS 1 and MIS 5.1, while cold-water species are high during MIS 2. An organic biomarker proxy, alkenone SST measured from core CSH1 ranges between 21 and 25 °C, with higher values during interglacials (MIS 1, 3.3, 5.1) and interstadials and lower values during glacials and Heinrich (H)/stadial events. Sea surface salinity (SSS) and the depth of the thermocline (DOT), reconstructed based on foraminifera isotopes and faunas, indicate dominant Kuroshio responses to an abrupt climate change event recorded in Greenland ice cores and in stalagmites in East China since ∼88 ka. The CSH1 SSS appears to be mainly controlled by the local river runoff and the Kuroshio, while the DOT change seems to be closely related to the strength of the Kuroshio and the latitudinal shift of the subarctic frontal zone. Our records suggest that, during MIS 1 and MIS 5.1, while global sea level was high, the Kuroshio was dominant; while during MIS 2, MIS 3 and MIS 4, with a low sea level, stronger winter Asian Monsoon (AM) and a more southerly subarctic front played important roles in governing the hydrographic characteristics in the OT. Spectral analysis of our multiproxy hydrographic records shows a dominant precessional period at ∼24 ka. Our hydrographic records, such as SST, SSS and DOT, from a site near the modern Tsushima Warm Current show regional responses corresponding mainly to the global sea level, the Kuroshio, AM and subarctic front, factors which are consistently invoked in the interpretations of other regional records from the OT.
Tags: carbon , oxygen , ocea , clim , mulitcarb

Links between southwestern tropical Indian Ocean SST and precipitation over southeastern Africa over the last 17 kyr
Palaeogeography, Palaeoclimatology, Palaeoecology (2014)
Syee Weldeab, David W. Lea, Hedi Oberha??nsli, Ralph R. Schneider

Time series of Mg/Ca, Ba/Ca, and ??18O analyzed in tests of surface-dwelling planktonic foraminifer Globigerinoides ruber from two marine sediment cores recovered in the Mozambique Channel off the Zambezi River, southwestern tropical Indian Ocean, reveal climate variability over the last 17kyr. Analysis of samples collected from the water column of the Mozambique Channel validates that Mg/Ca in G. ruber reflects calcification temperatures at 0-30m water depth and that the surface water of the southwestern Indian Ocean is very sensitive to dissolved Ba input from adjacent rivers. Foraminiferal Ba/Ca and Mg/Ca time series are used to reconstruct hydrological and thermal changes over southeastern African and southwestern tropical oceans. The Mg/Ca-based sea surface temperature (SST) estimates indicate that the thermal evolution of the tropical southwestern Indian Ocean followed, within age model uncertainties, climate changes over Antarctica. The trend of the SST record is marked by a gradual warming from 24.7??0.6??C at 17.0??0.2kyr BP to 26.4??0.3??C at 10-11kyr BP interrupted by two prominent coolings of ~1.5??0.2??C and ~1??C centered at 15??0.1kyr BP and 13.4??0.2kyr BP, respectively. Declining SSTs in the early Holocene reach their minimum (25??C) at 8.7??0.2kyr BP and give way to stable thermal conditions over the Middle and Late Holocene. The Ba/Ca record indicates that the Zambezi basin experienced relatively wet conditions during the early phase of the last deglaciation, B??lling-Aller??d, and the early Holocene. These wet phases coincide with an increase of SST in the Mozambique Channel. In contrast, relatively dry conditions throughout the middle and late Holocene epoch are accompanied by relatively cold Mozambique Channel surface water. These shifts likely reflect a response to meridional shifts of the austral westerlies and subtropical front. These hypothesized shifts would have modulated the advection of cold Southern Ocean water into the Mozambique Channel. Changes in SST in the Mozambique Channel, and possible resultant changes in the zonal gradient in the tropical Indian Ocean, in turn, had a strong impact on the precipitation over southeastern Africa.
Tags: carbon , oxygen , ocea , clim , mulitcarb

Carbon isotopic disequilibrium between seawater and air in the coastal Northern South China Sea over the past century
Estuarine, Coastal and Shelf Science (2014)
Shendong Xu, Guodong Jia, Wenfeng Deng, Gangjian Wei, Weifang Chen, Chih An Huh

Six coastal sediment cores collected from the Northern South China Sea were dated by 210Pb and analyzed for stable carbon and oxygen isotope composition of planktonic foraminifer Globigerinoides ruber (??13CGr and ??18OGr). Three of these cores were located east of Hainan Island and the other three off the Pearl River Estuary (PRE). Surface seawater ??18O and dissolved inorganic carbon (DIC) ??13C were identified as the dominant factors controlling downcore variations of ??18OGr and ??13CGr, respectively. Results of ??13CGr were then used to study surface water ??13CDIC and its relation to ??13C of atmospheric CO2 (??13Catm) over the past century. Downcore records showed rather constant ??13CGr in cores off Hainan Island, but moderate decreases of ??13CGr, at rates between -0.006??? and -0.009??? per year, in cores off the PRE. Isotopic disequilibrium between ??13CDIC and ??13Catm was observed, with ??13CDIC apparently higher than expected at equilibrium with ??13Catm except at the site closest to the PRE. The relatively steady ??13CGr values east of Hainan Island were explained by balanced vertical mixing and biological pump, whereas the moderate ??13CGr decreases with time off the PRE were attributable to fluvial input of terrestrial carbon.
Tags: carbon , oxygen , geol , ocea , mulitcarb

Extreme warming of tropical waters during the Paleocene-Eocene thermal maximum
Geology (2014)
T. Aze, P. N. Pearson, A. J. Dickson, M. P S Badger, P. R. Bown, R. D. Pancost, S. J. Gibbs, B. T. Huber, M. J. Leng, A. L. Coe, A. S. Cohen, G. L. Foster

The Paleocene-Eocene Thermal Maximum (PETM), ca. 56 Ma, was a major global environmental perturbation attributed to a rapid rise in the concentration of greenhouse gases in the atmosphere. Geochemical records of tropical sea-surface temperatures (SSTs) from the PETM are rare and are typically affected by post-depositional diagenesis. To circumvent this issue, we have analyzed oxygen isotope ratios ({delta}18O) of single specimens of exceptionally well-preserved planktonic foraminifera from the PETM in Tanzania ([~]19{degrees}S paleolatitude), which yield extremely low {delta}18O, down to <-5{per thousand}. After accounting for changes in seawater chemistry and pH, we estimate from the foraminifer {delta}18O that tropical SSTs rose by >3 {degrees}C during the PETM and may have exceeded 40 {degrees}C. Calcareous plankton are absent from a large part of the Tanzania PETM record; extreme environmental change may have temporarily caused foraminiferal exclusion.
Tags: carbon , oxygen , ocea , clim , mulitcarb

Oxygen isotope analyses of biogenic opal and quartz using a novel microfluorination technique.
Rapid communications in mass spectrometry : RCM (2013)
Anthony J Menicucci, Joy a Matthews, Howard J Spero

RATIONALE: Measuring δ(18)O values in silicates is difficult and hazardous in comparison with measurements of carbonate minerals due to the difficulty in breaking Si-O-Si bonds. A novel method for measurement of δ(18)O values from quartz and biogenic silica utilizing high-temperature pyrolysis with continuous-flow isotope ratio mass spectrometry (CF-IRMS) is presented. METHODS: Samples were prepared by offline dehydroxylation/dehydration under vacuum at 1060°C. The dehydroxylated samples are mixed with polytetrafluoroethylene (PTFE) powder (2.3:1 PTFE/Si) and graphite in silver foil capsules and reacted in a vario PYRO cube TC/EA system in a glassy carbon reaction tube. Quartz and biogenic opal samples react with available carbon in a microfluorination environment upon decomposition of the PTFE, producing CO for analysis via CF-IRMS. RESULTS: Silicate samples reacted quantitatively, producing data with yields ≥88% from ~400 µg samples. Multiple analyses with international standards demonstrated accuracy for replicate measurements (1σ range ±0.3-0.6‰), comparing favorably with previously published techniques. CONCLUSIONS: New data produced with the microfluorination technique are comparable with data from studies using existing methodologies. The microfluorination technique has the potential to greatly increase the number of laboratories producing silicate oxygen isotope data for mineralogic, paleoclimatic and biogeochemical applications.
Tags: oxygen , geol , ecol , ocea , elem

Environmental controls on coral skeletal δ 13 C 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

Migration of saithe (Pollachius virens) in the Northeast Atlantic
ICES Journal of Marine Science (2013)
Eydna ?? Homrum, Bogi Hansen, Sigurur P??r J??nsson, Kathrine Michalsen, Julian Burgos, David Righton, Petur Steingrund, Tore Jakobsen, R??gvi Mouritsen, Hj??lmar H??t??n, Hlynur Armannsson, J??kup Sverri Joensen

Saithe (Pollachius virens) stocks in the Northeast Atlantic intermingle as a result of migration among stock areas. The extent of mi- gration has been poorly quantified. Here, we estimate measures of the migration based on existing tagging data from Icelandic, Faroese and Continental (Scotland, North Sea and Norway) waters. Saithe tagged in Icelandic waters were seldom caught outside Icelandic waters (,1% of tag returns), whereas 42% of adult saithe tagged in Faroese waters were recaptured outside Faroese waters. Of adult saithe tagged in Norwegian waters 6.6% were recaptured outside Continental waters. In broad terms, there was a net migra- tion of saithe towards Icelandic waters. The distance between tagging and recapture increased with increasing size and age, with saithe tagged in Norwegian waters moving the longest distances. The results demonstrate significant, but variable, migration rates of adult saithe in the Northeast Atlantic. More detailed studies are needed to clarify the mechanisms behind the migration and what causes the differences among the areas.
Tags: carbon , oxygen , ocea , clim , mulitcarb

100-year ecosystem history elucidated from inner shelf sediments off the Pearl River estuary, China
Marine Chemistry (2013)
Guodong Jia, Shendong Xu, Weifang Chen, Fei Lei, Yang Bai, Chih-An Huh

In this paper, we analyze the organic geochemistry of four sediment cores recovered from a cross-shelf tran- sect offshore from the Pearl River Estuary, China, in an attempt to determine the impact of anthropogenic ac- tivity on carbon burial and phytoplankton community structure over the past century. Downcore total organic carbon (TOC) was found to be predominantly of marine origin, as indicated by the TOC:TN ratio, δ13Corg, and the branched and isoprenoid tetraether (BIT) index. Profiles of degradation-corrected marine or- ganic carbon (MOCcorr) show an asynchronous history, with a gradual increase beginning in the 1940s at the proximal sites (A9 and A7), in the 1970s at the central site (A6), and after 2000 at the distal site (A5). Follow- ing this gradual increase, a concurrent but more rapid rise in MOCcorr occurred after about 1980, except at site A5. This rise in MOCcorr is probably associated with enhanced primary productivity related to an increase in the fluvial nutrient influx, as indicated by upcore increases in δ13Corg, δ15N, and phyto-sterol lipids. At sites A7 and A6, phyto-sterol compound ratios suggest a progressive decrease in diatoms, but an increase in non-diatom algae in the community since the 1940s. However, inshore at site A9, the community structure, as well as δ15N, remained almost unchanged. Distance from the shore may be one cause of the asynchronous increase in MOCcorr along the cross-shelf transect. However, our results imply that changes in community structure may also modulate MOC burial by partially offsetting the effect of growth in primary productivity. In addition, the CaCO3:MOCcorr ratio decreased significantly at sites A7 and A6 over the past 30 years, which may suggest a relative decrease in marine carbonate production that may have acted as a negative feedback to limit atmospheric CO2 rises.
Tags: carbon , nitrogen , ecol , ocea , elem

Trophic ecology of sharks in the mid-east Pacific ocean inferred from stable isotopes
Journal of Ocean University of China (2013)
Yunkai Li, Yi Gong, Xinjun Chen, Xiaojie Dai, Jiangfeng Zhu

As apex predators, sharks are of ecological and conservation importance in marine ecosystems. In this study, trophic positions of sharks were estimated using stable isotope ratios of carbon and nitrogen for five representative species caught by the Chinese longline fleet in the mid-east Pacific, i.e., the blue shark (Prionace glauca), the bigeye thresher shark (Alopias superciliosus), the silky shark (Carcharhinus falciformis), the scalloped hammerhead (Sphyrna lewini), and the oceanic whitetip shark (Car- charhinus longimanus). Of these species, oceanic whitetip shark has the lowest trophic level and mean δ15N value (3.9 and 14.93‰ ± 0.84‰), whereas bigeye thresher shark has the highest level/values (4.5 and 17.02‰ ± 1.21‰, respectively). The bigeye thresher shark has significantly higher δ15N value than other shark species, indicating its higher trophic position. The blue shark and oceanic whitetip shark has significantly higher δ13C values than bigeye thresher shark, silky shark and scalloped hammerhead, possibly due to different diets and/or living habitats. The stable isotope data and stomach content data are highly consistent, suggesting that sta- ble isotope analysis supplements traditional feeding ecology study of sharks, and thus contributes to understanding their trophic linkage.
Tags: carbon , nitrogen , ecol , ocea , elem