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EARTH SCIENCE > OCEANS > OCEAN CHEMISTRY > STABLE ISOTOPES

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  • Data shows gross body measurements of lantern shellfish (Laternula elliptica) collected by divers at McGrady Cove; Brown Bay Inner, and Shannon Bay. Measurements include length, width, and height of shell and weight with shell on and shell off.

  • Data shows carbon and nitrogen stable isotope concentration in siphon tissue of laternula elliptica from three sites adjacent to Casey Station. McGrady Cove, Brown Bay Inner and Shannon Bay. All shellfish were collected by divers during the 2014/15 summer season. Samples were sent to Cornell University Stable Isotope laboratory for analysis.

  • Overview of the project and objectives: To investigate whether nitrate uptake and processes other than nitrate uptake by phytoplankton are significant and show spatial variability possibly induced by varying availability of Fe and other parameters in the region, seawater was collected from CTD (Conductivity, Temperature and Depth) and TMR (Trace Metals Rosette) casts jointly with the nutrient sampling, as well as well as sea-ice collected from Bio ice-core types on Ice Station, for analysis of nitrate d15N, d18O isotopic composition. Results have been interpreted in the light of prevailing nitrate-nutrient concentrations (Belgian team) and N-uptake regimes for the Ice Stations (new vs. regenerated production and nitrification; see Silicon, Carbon and Nitrogen in-situ incubation Metadata file). Methodology and sampling strategy: Samples for isotopic composition of nitrate were collected from the CTD rosette, TMR and Bio ice-core jointly with the nutrient sampling. Sea-ice sampling: sampling strategy follows ice stations deployment via Bio ice-core type. Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). All samples were filtered on 0.2 microns acrodiscs and kept at -20 degrees C till analysis in the home-based laboratory. We applied the denitrifier method elaborated by Sigman et al. (2001) and Casciotti et al. (2002). This method is based on the isotopic analysis of delta 15N and delta 18O of nitrous oxide (N2O) generated from nitrate by denitrifying bacteria lacking N2O-reductase activity. As a prerequisite the nitrate concentrations need to be known (nutrients analysis in the home lab.) as this sets sample amount provided to the denitrifier community. Briefly, sample nitrate is reduced by a strain of denitrifying bacteria (Pseudomonas aureofaciens) which transform nitrate into N2O, but lack the enzyme to produce N2. N2O is then analysed for N, O isotopic composition by IRMS (Delta V, Thermo) after elimination of CO2, volatile organic carbon and further cryogenic focusing of N2O (Mangion, 2011). Casciotti K.L., D.M.Sigman, M.G. Hastings, J.K. Bohlke and A. Hilkert, 2002. Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method, Analytical Chemistry, 74 (19): 4905-4912. Mangion P., 2011. Biogeochemical consequences of sewage discharge on mangrove environments in East Africa, PhD Thesis, Vrije Universiteit Brussel, 208 pp. Sigman D.M., Casciotti K.L., Andreani M., Barford C., Galanter M. and J.K. Bohlke, 2001. A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater, Analytical Chemistry, 73: 4145-4153.

  • Overview of the project and objectives: To investigate whether the Nitrogen - Silicon - Carbon biogeochemical system functions in the Antarctic Marginal Ice Zone and shows spatial variability possibly induced by varying availability of Fe and other parameters in the region. This toolbox is part of project 4051 - samples were taken (1) on the same sea-ice site or very close than the one used for Trace Metal sampling; (2) via Trace Metal Rosette TMR; (3) via Conductivity Temperature and Depth CTD Rosette. It is also part of project 4073 since some intercalibration studies were conducted in collaboration with the primary production team. Three main tools were used which can be either independently or intricately studied. For this reason the complete set of sampling done for this stable isotope toolbox is summarized in one excel file which is duplicated and attached to three child metadata records. Same reasoning for raw data acquired on boar and on field information. This parent metadata record has thus three child metadata records. Each of the child metadata files explain individually the different approaches which were treated together by the same team to resolve the main question of sea-ice biogeochemical system functioning via the use of stable isotope ratio tools. The details of each are in the respective metadata records. The data are attached to this metadata record. METADATA FILES are: - 13C, 15N, 30Si in-situ incubation experiments during SIPEX 2 - Nitrogen and oxygen isotopic composition of nitrate during SIPEX 2 - Delta13C signal of brassicasterol and cholesterol in the Antarctic Sea-ice / Is there particulate barium in sea-ice?

  • This data features stable carbon and nitrogen isotopes of co-occurring Southern Ocean pteropods in order to estimate and compare their Bayesian isotopic niches. Other data includes station number, latitude and longitude, species names and sample ID. Details for each column are as follows: A: "species" - Species analysed including, "clio" = Clio pyramidata f. sulcata; "clione" = Clione limacina antarctica; "spongio" = Spongiobranchaea australis; "Large-fraction POM" = large-fraction particulate organic matter; "Small-fraction POM" = small-fraction particulate organic matter B: "speciesID" - Sample ID = unique identifier from Central Science Laboratory, University of Tasmania C: "station" = CTD number (KAxis research voyage) D: "date" = Date of sample (RMT-8 net trawl, KAxis research voyage) E: "lat" = Latitude (degS) F: "long" = Longitude (degE) G: "%C" = percent carbon (no unit) H: "%N" = percent nitrogen (no unit) I: "C:N (bulk)" = uncorrected (raw) carbon-to-nitrogen ratio (no unit) J: "delta 13C (bulk)" = uncorrected (raw) stable carbon isotope values (‰) H: "delta 15N (bulk)" = uncorrected (raw) stable nitrogen isotope values (‰) L: "notes" = samples may be duplicated or triplicated M: "atomic C:N" = C:N (bulk) x 14/12 (no unit) N: "atomic L" = 93/(1+ (1/((0.246 x atomic C:N) - 0.775))) O: "L" = 93/(1+(1/((0.246 x C:N (bulk) - 0.775))) P: "delta 13C (Kiljunen)" = delta 13C (bulk) corrected using formula by Kiljunen et al. 2006 Q: "delta 13C (atomic Kiljunen)" = delta 13C (bulk) corrected using formula by Kiljunen et al. 2006 and atomic L value (column N) R: "delta 13C (Post)" = delta 13C (bulk) corrected using formula by Post et al. 2007 S: "delta 13C (Weldrick)" = delta 13C (bulk) corrected using formula by Weldrick et al. 2019 T: "delta 13C (atomic Smyntek)" = delta 13C (bulk) corrected using formula by Smyntek et al. 2007 and atomic L value (column N) U: "delta 13C (Smyntek)" = delta 13C (bulk) corrected using formula by Smyntek et al. 2007 V: "delta 13C (Logan)" = delta 13C (bulk) corrected using formula by Logan et al. 2008 W: "delta 13C (Syvaranta)" = delta 13C (bulk) corrected using formula by Syvaranta and Rautio 2010 The analysis is featured within a recently accepted paper titled "Trophodynamics of Southern Ocean pteropods on the southern Kerguelen Plateau" peer-reviewed for Ecology and Evolution (2019). It is based on samples collected during the KAxis research voyage, 2015/16.

  • Data show results of carbon and nitrogen stable isotopes in muscle tissue of Trematomus bernacchii collected at 5 sites adjacent to Casey Station. Sites are contaminated Brown Bay, near Wilkes Station, Shannon Bay and reference O'Brien Bay and Sparkes Bay. Approximately 1cm3 of muscle tissue from the left side of each fish was taken for stable isotopes analysis.

  • Hydrochemistry of surface water. Parameters measured=salinity, oxygen, co2, oxygen isotope species, nutrients. All data have been stored in a single excel file. Measurements were made on the CEAMARC voyage of the Aurora Australis - voyage 3 of the 2008-2008 summer season. See other CEAMARC metadata records for more information.

  • These data describe the locations, dates, time, etc where biogeochemistry data were collected on the CEAMARC-CASO cruise in the 2007/2008 Antarctic season. See the CEAMARC-CASO events metadata record for further information. Sample codes are not descriptive. CEMARC/CASO column have underway data (no link to group site) as well as the CEAMARC and CASO sampling locations. Events are recorded by number and the associated type of sample taken. CTD - 0.4 um filtered water sample. Box corer - diatom scrape. Beam Trawl AAD - sponge sample. PHY - phytoplankton sample taken from inline surface seawater system. Van Veen grab - sediment scrape. WAT - surface water sample passed through 0.4 um filter. Description column explains the samples in more detail - eg information on what size fraction the phytoplankton were filtered at. Litres column describes the volume of water that was filtered. Depth is in metres. Time is local time. Temperature is degrees C. Storage location was for shipboard use only. The "other" column details any extra information that may be useful to the sample for example #2153 refers to a sample id code that the French CEAMARC group was using to code for their samples. Our aim for this voyage was to collect surface phytoplankton and water samples across a transect of the Southern Ocean, and to collect benthic sponge and coral samples in Antarctica, to (i) measure the Ge/Si and Si isotope composition to construct a nutrient profile across the Southern Ocean, and to test and calibrate these parameters as proxies for silica utilisation; and (ii) measure the B isotope composition to test the potential of biogenic silica to be used as a seawater pH proxy. We collected phytoplankton, sponges, diatom sediment scrapes and water samples at strategic locations to ensure that the entire water column was surveyed. The data that were collected were used in collaboration with palaeoenvironmental data from sediment cores and experimental culture experiments on diatoms and sponges to gain a better understanding of historical distributions of Silicon and pH in the Southern Ocean.

  • Water samples were collected from the seawater line on the Aurora Australis during the K-Axis voyage. They were filtered so that two fractions of each sample were collected: a fraction that was between 1.2 and 210 um and a fraction that was between 210 and 1000 um. A 47 mm diameter 1000 um mesh was placed upstream of all samples, and this prevented larger particles (e.g. zooplankton) from entering the samples. The underway water was taken from the pCO2 rig at 1.4 to 1.5 atmospheres. All samples were collected on 25 mm diameter 1.2um Sterlitech silver membrane filters. The greater than 210 samples were collected on mesh and refiltered onto silver filters. The filters were stored frozen until they were processed in Hobart. Subsamples of the filters were analysed at the Central Science Laboratories, University of Tasmania to determine elemental N and C. The remainder of the filters were analysed by ANSTO (NSW) to determine delta15N and delta13C. Volumes are in litres, and the values for the nitrogen isotopes are presented as ratios.

  • Zooplankton were collected during the winter-spring transition during two cruises of the Aurora Australis: SIPEX in 2007 and SIPEX II in 2012. As part of the collections sea ice cores were collected to describe the ice habitat during the period of zooplankton collections. Ice cores were taken with a 20 cm diameter SIPRE corer and sectioned in the field with an ice core. Particulate organic matter (POM) and animals from the zooplankton (water column) and the sea ice cover (meiofauna) were processed for stable isotopes - delta 13 Carbon and delta 15 Nitrogen.