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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:

Assessing the potential of amino acid δ 13 C patterns as a carbon source tracer in marine sediments : e ff ects of algal growth conditions and sedimentary diagenesis
Biogeosciences (2015)
T Larsen, L T Bach, R Salvatteci, Y V Wang, N Andersen, M Ventura

Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to a substantially larger degree than suggested by changes in total organic nitrogen and carbon content. It is uncertain whether archaea may have contributed to sedimentary δ13CAA patterns we observe, and controlled culturing studies will be needed to investigate whether δ13CAA patterns can differentiate bacterial from archeal sources. Further research efforts are also needed to understand how closely δ13CAA patterns derived from hydrolyzable amino acids represent total sedimentary proteineincous material, and more broadly sedimentary organic nitrogen. Overall, however, both our culturing and sediment studies suggest that δ13CAA patterns in sediments will represent a novel proxy for understanding both primary production sources, and the direct bacterial role in the ultimate preservation of sedimentary organic matte
Tags: carbon , nitrogen , ocea , elem

Polybrominated diphenyl ethers in thirteen shark species from offshore and coastal waters of Korea
Marine Pollution Bulletin (2015)
Hyun-Kyung Lee, Sang-Jo Kim, Yunsun Jeong, Sunggyu Lee, Woochang Jeong, Won-Chan Lee, Eun-Jung Choy, Chang-Keun Kang, Hyo-Bang Moon

Limited reports are available on polybrominated diphenyl ethers (PBDEs) in sharks. In this study, PBDEs were measured in dorsal muscles (n = 105) from 13 shark species collected from offshore and coastal waters of Korea. The PBDE concentrations varied greatly not only among species but also within species of sharks. The major PBDE congeners detected in our samples were BDEs 47, 28, 99, 153, 100, and 154. Concentrations of PBDEs in sharks in this study were lower than those reported for previous studies. The high PBDE concentrations were found for aggressive shark species. Inter-species differences in the concentrations and accumulation profiles of PBDEs are explained by differences in feeding habits and sampling locations. Several contributing factors such as growth velocity, trophic level, and local contamination may affect the bioaccumulation of PBDEs in sharks. The present study provides baselines for the occurrence and accumulation status of PBDEs in various shark species
Tags: nitrogen , ecol , ocea , poll , elem

Latitudinal δ13C and δ15N variations in particulate organic matter (POM) in surface waters from the Indian ocean sector of southern ocean and the tropical Indian ocean in 2012
Deep Sea Research Part II: Topical Studies in Oceanography (2015)
Melena a. Soares, Parli V. Bhaskar, Ravidas K. Naik, Deepti Dessai, Jenson George, Manish Tiwari, N. Anilkumar

This study uses the carbon isotope values (δ13C) to determine how environmental deterioration is expressed in the δ13C values of vegetation and gazelles in the southern Levant. The ultimate goal is to use these modern data to predict the climatic impact of the Younger Dryas (YD). Climatic deterioration associated with the YD has been cited as the trigger for the transition to agriculture in the southern Levant. However, the evidence for the local severity of this climatic event is equivocal. There is disagreement over whether Mediterranean forest was succeeded by arid adapted steppic plant communities in what has been termed the Natufian ‘core area’. The modern data show a moderately negative regression slope between aridity and the δ13C values of both modern C3 plants and gazelle horn keratin within the Mediterranean phytogeographic belt. This pattern is expressed in both seasonal and annual datasets. The incorporation of a C4 plant component into gazelle diets is evident in the arid Mediterranean region, and is more pronounced in the dry season. The latter is apparent even despite interference caused by gazelle foraging on cultivated land. Based on the present day data, it is predicted that the succession of Mediterranean forest by open steppic vegetation would cause a positive shift of >2‰ in the δ13C values of C3 plants and gazelles. The argument is based on the response of C3 vegetation to growth under increasing water stress conditions and the current distribution of C3 and C4 vegetation in relation to rainfall. This study presents a new tool with the potential to assess the climatic severity of the YD and its effect on Natufian foraging strategies.

Effect of emersion/immersion cycles on the elemental and isotopic compositions of the organic matter from surface sediments of an intertidal mud bank (French Guiana): a preliminary study.
Rapid communications in mass spectrometry : RCM (2015)
Swanne Gontharet, Luis Felipe Artigas, Olivier Mathieu, Jean Levêque, Marie-Jeanne Milloux, Jacinthe Caillaud, Sylvie Philippe, Sandric Lesourd, Antoine Gardel

RATIONALE: In various marine environments, the combination of elemental ratios and stable isotopic compositions is usually used to trace the sources of organic matter (OM) in sediments. However, in intertidal areas, the sediments might be temporarily exposed to air during a more or less prolonged duration and the impact of this exposure on the latter parameter is unknown. METHODS: The spatial variations of atomic Total Organic Carbon (TOC) and Total Nitrogen (TN) ratios, and δ(13)C and δ(15)N values, were measured on surface sediments of French Guiana, at the beginning and the end of five consecutive days of emersion during equinoctial tides, as well as at the beginning of a new emersion phase after returning to a normal tidal cycle. The concentrations of chlorophyll a and phaeopigments in sediments were also measured, in order to estimate the influence of microphytobenthos (MPB), growing at surface sediments, on these geochemical parameters. RESULTS: The results showed that the emersion/immersion cycles influenced the development of MPB at the surface sediments, which, in turn, significantly controlled the spatio-temporal changes in the atomic elemental ratios and the δ(13)C values. This variability seemed not to be significantly altered by OM degradation. On the contrary, sediments were always (15) N-enriched compared with OM sources, indicating that OM diagenetic processes mainly controlled their spatio-temporal fluctuations. CONCLUSIONS: The [TOC/TN]atomic ratios and the δ(13)C values, indicating the primary signal of OM sources, represented the most reliable geochemical proxies for calculating the relative contribution of OM sources to sediments in environments characterized by variable air exposure duration. The use of δ(15)N values in such environments is limited by OM degradation processes but their variation might enable the nature and the degree of these processes to be identified.
Tags: carbon , nitrogen , soil , ocea

Late Pleistocene and Holocene sea-level change and coastal paleoenvironment evolution along the Iranian Caspian shore
Marine Geology (2015)
a.a. Kakroodi, S.a.G. Leroy, S.B. Kroonenberg, H.a.K. Lahijani, H. Alimohammadian, I. Boomer, A. Goorabi

abstract The level of theCaspianSea is influenced by riversmostly fromthehighlatitudesof theNorthernhemisphereand therefore any change of its catchments including temperature and precipitation directly reflects on Caspian Sea- level. Wereconstructed Late Pleistocene toHolocene Caspian Sea-level by amulti-disciplinary approach froma 27.7m long core in the SE corner of the Iranian Caspian coast in theGomishan Lagoon. Late Pleistocene deposits contain- ing typical Pleistocene fauna and dated around 20,120 cal yr BP borderedwith amajor hiatus indicating sea-level fall. Lagoonaldepositswithshellsdated at around10,590 cal yrBP suggest that, after thisdeep lowstand, aninitial transgression started, leading to landward advance of barrier–lagoon systemswhich still continuedwithout any lowstand until 8400 cal yr BP. This corresponded to a biofacies change from lagoonal to the deeper biofacies including diatom and Gastropoda species. Around 8400 cal yr BP sea-level started to fall again, and reddish oxidized sediments with abundant foraminifera (Ammonia beccarii) record a regressive phase around 7700cal yrBP.Themid-Holocene between15.7 and4.9 depths is characterized by a shallowmarine environment mostlywith high carbonate and gypsumcontents, and lagoonal and highstand tractwith no subaerial facies. The upper part of the core above a 4.9 m depth reflects at least five Late Holocene Caspian Sea-level cycles from 3260 cal yr BP onward. The Caspian Sea-levels are influenced both by global and regional events.
Tags: carbon , oxygen , geol , ocea , gashead

Tracing nutrient and organic matter sources and biogeochemical processes in the Sacramento River and Northern Delta: proof of concept using stable isotope data
U.S. Geological Survey (2015)
C. Kendall

Isotope and chemical data for samples collected during several overlapping studies in the Sacramento River and Delta conducted 2009-2011 is presented to evaluate the potential usefulness of stable isotope techniques for testing hypotheses about sources of nutrients and algae, and biogeochemical processes in section of the San Francisco Estuary. These data are used to provide an independent test of the hypothesis that ammonium derived primarily from waste-water treatment plants was inhibiting phytoplankton uptake of nitrate. These data represent approximately monthly samples from 15-20 sites along transects of the river and delta and were analyzed for the stable isotopic compositions of ammonium, nitrate, particulate organic matter, dissolved organic carbon, and water then used to demonstrate the viability of assessing the temporal and spatial variations in the sources, transport, and sinks of nutrients and organic matter in the Sacramento River and Delta Another main focus was to assess whether there were significant differences between the chemistry and isotopic compositions of mainstem Sacramento River samples and (1) samples from tributaries within the Cache/Yolo Slough Complex, and (2) samples from the main two distributaries of the Sacramento River downstream of the waste-water treatment plant: Miner Slough and Steamboat Slough. Using these data we present (1) "proof of concept" of the usefulness of isotope techniques combined with water chemistry and hydrological modeling in this ecosystem, (2) key findings from some of the ongoing parts of the studies, and (3) downloadable Excel files of the relevant isotope and chemistry data with associated metadata to facilitate these data being used for other investigations. The rationale was that if isotope techniques showed promise in identifying sources and processes in this ecosystem, a comprehensive multi-isotope approach would later be used for quantifying nutrient and organic matter sources and biogeochemical processes relevant to questions about causes of environmental problems. These more quantitative assessments are in progress.
Tags: carbon , nitrogen , oxygen , sulfur , geol , ocea , elem , gashead

Response of Long Lake sediments to Antarctic climate: A perspective gained from sedimentary organic geochemistry and particle size analysis
Polar Science (2015)
Badanal Siddaiah Mahesh, Anish Kumar Warrier, Rahul Mohan, Manish Tiwari, Anila Babu, Aswathi Chandran, Rajesh Asthana, Rasik Ravindra

Sediments from the pristine lakes of ice-free regions of Antarctica are a great source for proxies to reconstruct the effect of past-climate on the lake evolution and its response to Antarctic climate. A 50 cm long sediment core retrieved from Long Lake, a periglacial lake of Schirmacher Oasis in Dronning Maud Land was measured for elemental (C%, N% and C/N), isotopic (δ13C, δ15N) and particle size (sand-silt-clay percent) variation. The radiocarbon dated core spanning the last 48 cal ka BP has been deciphered for the lake's response to Antarctic climate. The C/N ratio (atomic ratio) predominantly indicates that the productivity has been autochthonous for majority of the down-core while the top 0–3 cm indicates that there has been addition of terrestrial organic matter into the lake system owing to longer ice-free conditions. The organic carbon shows significantly lower values (0.2%) throughout the glacial period and major part of the Holocene while the core-top values are consistent with the presence of a microbial mat which is reflected as higher organic carbon (12%). The δ13C and δ15N range from −33 to −9‰ and 2–18‰, respectively. The isotopic signals vary marginally for the entire glacial period (48–8 cal ka BP) suggesting an intense cold period. The gradual increase in C/N ratio, sand content and δ13C and decrease in δ15N beginning at about 6 cal ka BP suggest that the Long Lake experienced longer ice-free conditions owing to sustained warmer Holocene conditions suggesting that the ice-cover over the Long Lake persisted well through early-Holocene. The sand and silt percent shows inverse correlation likely reflecting the warmer and colder conditions. The Holocene is characterised by higher sand content owing to melting of ice due to warmer conditions. The Long Lake's response to Antarctic climate is reflected in its response to the ice-cover conditions which regulates the productivity and sedimentation in the lake system.

Holocene Climatic Optimum centennial-scale paleoceanography in the NE Aegean (Mediterranean Sea)
Geo-Marine Letters (2015)
Maria V. Triantaphyllou, Alexandra Gogou, Margarita D. Dimiza, Sofia Kostopoulou, Constantine Parinos, Grigoris Roussakis, Maria Geraga, Ioanna Bouloubassi, Dominik Fleitmann, Vassilis Zervakis, Dimitris Velaoras, Antonia Diamantopoulou, Angeliki Sampatak

Combined micropaleontological and geochemical analyses of the high-sedimentation gravity core M-4G provided new centennial-scale paleoceanographic data for sapropel S1 deposition in the NE Aegean Sea during the Holocene Climatic Optimum. Sapropel layer S1a (10.2–8.0 ka) was deposited in dysoxic to oxic bottom waters characterized by a high abundance of benthic foraminiferal species tolerating surface sediment and/or pore water oxygen depletion (e.g., Chilostomella mediterranensis, Globobulimina affinis), and the presence of Uvigerina mediterranea, which thrives in oxic mesotrophic-eutrophic environments. Preservation of organic matter (OM) is inferred based on high organic carbon as well as loliolide and isololiolide contents, while the biomarker record and the abundances of eutrophic planktonic foraminifera document enhanced productivity. High inputs of terrigenous OM are attributed to north Aegean borderland riverine inputs. Both alkenone-based sea surface temperatures (SSTs) and δO18 G. bulloides records indicate cooling at 8.2 ka (S1a) and ~7.8 ka (S1 interruption). Sapropelic layer S1b (7.7–6.4 ka) is characterized by rather oxic conditions; abundances of foraminiferal species tolerant to oxygen depletion are very low compared with the U. mediterranea rise. Strongly fluctuating SSTs demonstrate repeated cooling and associated dense water formation, with a major event at 7.4 ka followed by cold spells at 7.0, 6.8, and 6.5 ka. The prominent rise of the carbon preference index within the S1b layer indicates the delivery of less degraded terrestrial OM. The increase of algal biomarkers, labile OM-feeding foraminifera and eutrophic planktonic species pinpoints an enhanced in situ marine productivity, promoted by more efficient vertical convection due to repeated cold events. The associated contributions of labile marine OM along with fresher terrestrial OM inputs after ~7.7 ka imply sources alternative/additional to the north Aegean riverine borderland sources for the influx of organic matter in the south Limnos Basin, plausibly related to the inflow of highly productive Marmara/Black Sea waters.
Tags: carbon , oxygen , ocea , clim , mulitcarb

Importance of kelp-derived organic carbon to the scallop Chlamys farreri in an integrated multi-trophic aquaculture system
Chinese Journal of Oceanology and Limnology (2015)
Qiang Xu, Fei Gao, Hongsheng Yang

Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture (IMTA) systems. A beneficial relationship between seaweed and bivalve in the seaweed-based IMTA system has been confirmed, but the trophic importance of seaweed-derived particulate organic materials to the co-cultured bivalve is still unclear. We evaluated the trophic importance of the kelp Saccharina japonica to the co-cultured scallop Chlamys farreri in a typical IMTA farm in Sungo Bay (Weihai, North China). The dynamics of detritus carbon in the water were monitored during the culturing period. The proportion of kelp-derived organic matter in the diet of the co-cultured scallop was assessed via the stable carbon isotope method. Results showed that the detritus carbon in the water ranged from 75.52 to 265.19 μg/L, which was 25.6% to 73.8% of total particulate organic carbon (TPOC) during the study period. The amount of detritus carbon and its proportion in the TPOC changed throughout the culture cycle of the kelp. Stable carbon isotope analysis showed that the cultured scallop obtained 14.1% to 42.8% of its tissue carbon from the kelp, and that the percentages were closely correlated with the proportion of detritus carbon in the water (F =0.993, P= 0.003). Evaluation showed that for 17 000 tons (wet weight) of annual scallop production, the kelp contributed about 139.3 tons of carbon (535.8 tons of dry mass). This confirms that cultured kelp plays a similar trophic role in IMTA systems as it does in a natural kelp bed. It is a major contributor to the detritus pool and supplies a vital food source to filter-feeding scallops in the IMTA system, especially during winter and early spring when phytoplankton are scarce
Tags: carbon , ecol , ocea , elem

Non-equilibrium fractionation of stable carbon isotopes in chemosynthetic mussels
Chemical Geology (2014)
K. Nedoncelle, N. Le Bris, M. de Rafélis, N. Labourdette, F. Lartaud

Chemosynthetic bivalves from deep-sea hydrothermal vents exploit the energy derived from chemical compounds, such as methane, sulfide or hydrogen, using symbiotic bacteria that are able to fix inorganic carbon. Available chemical resources in their habitat vary widely at various scales, from the vent field scale to the micro-habitat scale. Parallel to this environmental heterogeneity, Bathymodiolus species are considered to be flexible in their energy acquisition pathways.The goal of this study was to determine whether the isotopic compositions archived in the shells of hydrothermal vent mussels could trace chemical energy sources and their variability over spatial and temporal scales. Two different species (Bathymodiolus azoricus and Bathymodiolus thermophilus) inhabiting three vent fields with contrasted geochemical features on the Mid Atlantic Ridge (MAR; Rainbow and Menez Gwen) and the East Pacific Rise (EPR; 9°47'N), were considered for carbon isotopes and growth rate variation along the shell length. The study revealed that 13C fractionation between shells and seawater is higher than expected from calcite-bicarbonate equilibrium fractionation, suggesting a significant influence of the chemosynthetic pathway on the shell composition. Furthermore, significant differences in δ13Cshell fractionation with respect to seawater are observed between sites and habitats of the two MAR vent fields, suggesting that different chemosynthetic pathway (e.g. methanotrophic and thiotrophic) could lead to variable enrichments of the shell in 13C. Mussels supposed to rely more largely on methanotrophy (at Rainbow where free sulfide is unavailable) display a lower δ13Cshell values than mussels relying also on sulfide-oxidizing symbiosis (at Menez Gwen). Variability in δ13Cshell between habitats, or between individuals within the same assemblage, could thus reflect differences in the symbiosis activity at a micro-habitat scale. These isotopic signatures could provide useful information on the relationships between micro-habitat properties, symbiont activity and shell mineralization.
Tags: carbon , oxygen , ocea , mulitcarb