Pacific Arctic Stable Isotope Synthesis

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Frequently anticipated questions:


What does this data set describe?

Title: Pacific Arctic Stable Isotope Synthesis
Abstract:
This dataset is a synthesis of carbon and nitrogen stable isotope data from several studies collected into a single GIS feature class. The data cover the Pacific-influenced coastal shelf ecosystem of the Arctic Ocean. Data points include isotopic ratios of del C-13 and del N-15. Additional metadata such as the names of the original data collectors are included as attributes of the feature class when available. Carbon isotope ratios are a good indicator of carbon sources of the food web because of their small enrichment steps between consecutive consumers (0-1‰) and nitrogen isotope ratios are good indicators of trophic level (TL) because of the larger enrichment step of 3-4‰ between TL.
Supplemental_Information:
This dataset was compiled from various other studies performed throughout several decades in the Arctic Ocean. Data were compiled in spreadsheet form and then imported into GIS as a single feature class. Data source information is provided as attributes for each data point.
Benthic samples for stable isotopic measurements (13C and 15N) were obtained from both van Veen grabs and benthic trawls. Zooplankton and samples of particulate organic matter (POM) were also collected for isotopic analysis; these data were used to develop our coupled benthic-pelagic conceptual food web model. In addition to biota, replicate 1 cc surface samples of undisturbed sediment were frozen for sediment isotopic analysis. Prior to 2002, sub-samples of freeze-dried tissue for isotopic analysis were treated with dilute HCl for several hours to remove carbonates and then dried at 70oC. About 15-20 mg of dried tissue samples were ground with 1 g of CuO and combusted in evacuated quartz tubes. The liberated carbon dioxide and nitrogen were cryogenically cleaned and stored in sealed glass tubes until analysis. Mass spectrometry was conducted using a VG Isogas SIRA 9 Mass Spectrometer. Machine precision was approximately ±0/2% for δ13C and ±0.3% for δ15N. Results are expressed in standard δ notation relative to carbonate PeeDeeBelemnite and atmospheric nitrogen where:
δ 13C or δ 15N (‰) = [Rsample/Rstandard) – 1] x 1000
and R = (13C/12C or 15N/14N), respectively.
After 2002, tissues for isotope analyses were processed on an easier and more accurate system. All biota were dried in aluminum dishes at 60 °C following removal of extraneous organic matter. When possible, soft tissues were removed from shelled organisms. All invertebrate samples were soaked in 1 N HCl for several hours to remove carbonates, rinsed in distilled water, and then dried. Muscle or body wall tissue was analyzed from bivalves, gastropods, large crustaceans (euphausiids and amphipods), and fish; all other organisms were analyzed whole. Entire organisms or tissues are manually ground for isotopic analyses. Replicate analyses reflected the analysis of individual organisms, not composite samples. All samples were analyzed on an automated system for coupled δ 13C and δ 15N measurements using a Finnegan MAT Delta Plus mass spectrometer attached to an elemental analyzer (CE Instruments, NC 2500). Samples were combusted at 1,020 °C and then injected into the mass spectrometer with continuous flow. Results are expressed in standard δ notation as seen above. Secondary and NBS calibration standards were routinely for cross-calibration checks of tank reference gases, against which all samples are run. The resulting data were reproducible to within ± 0.2 ‰. Machine analytical error was ± 0.15 ‰.
  1. How should this data set be cited?

    Ken Dunton, Marine Science Institute, The University of Texas at Austin, Professor, 20130227, Pacific Arctic Stable Isotope Synthesis: Earth Observing Laboratory.

    Online Links:

    • pacmars.eol.ucar.edu

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -180.000000
    East_Bounding_Coordinate: 180.000000
    North_Bounding_Coordinate: 79.144987
    South_Bounding_Coordinate: 57.882074

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 01-Jan-1980
    Ending_Date: 10-Aug-2010
    Currentness_Reference:
    Temporal period extent is based on sample dates. In some cases, only sample year was provided by the original data source, while in other cases, no temporal context was provided at all.
    The dates/times of the dataset refer to sample dates.

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Entity point (4094)

    2. What coordinate system is used to represent geographic features?

      The map projection used is North Pole Stereographic.

      Projection parameters:
      Longitude_of_Projection_Center: 0.0
      Latitude_of_Projection_Center: 90.0
      False_Easting: 0.0
      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000000006783107409091829
      Ordinates (y-coordinates) are specified to the nearest 0.000000006783107409091829
      Planar coordinates are specified in meter

      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.

  7. How does the data set describe geographic features?

    stable_isotope_synthesis
    Locations of stable isotope samples (Source: Various investigators over several decades collected the data compiled into this dataset)

    FID
    Internal feature number. (Source: Esri)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: Esri)

    Coordinates defining the features.

    CruiseID
    Cruise identifier (Source: Various)

    StationNum
    Station number or unique identifier (Source: Assigned for each cruise by investigator or cruise planner)

    StationNme
    Station name (Source: Assigned for each cruise by investigator or cruise planner)

    DataDate
    Sample date (Source: Recorded for each cruise by investigator)

    DataYear
    Sample year (Source: Compiled from sample dates or publications)

    DataTime
    Sample times (Source: Recorded for each cruise by investigator)

    TimeZone
    Time zone (Source: Global time zones)

    UTCOffset
    Offset in hours from Coordinated Universal Time (UTC) (Source: International Telecommunications Union Recommendation (ITU-R TF.460-6))

    Latitude
    Latitude (Source: World Geodetic System)

    Longitude
    Longitude (Source: World Geodetic System)

    Depth
    Depth that samples were taken, in meters. Depths are positive in the downward direction. Null values are indicated by -999.99. (Source: Depths were recorded by sensors on each cruise)

    WaterDepth
    Water depth to sea floor at the current location, in meters. Depths are positive in the downward direction. Null values are indicated by -999.99. (Source: Depths were recorded by sensors on each cruise)

    delC13
    del C-13 isotopic ratio, per mille. Null values are indicated by -999.99. Method of measurement is indicated in the Method attribute when available. (Source: Data collector)

    delN15
    del N-15 isotopic ratio, per mille. Null values are indicated by -999.99. Method of measurement is indicated in the Method attribute when available. (Source: Data collector)

    TSN
    Taxonomic serial number, a unique identifier for taxa. Missing or "not applicable" values are indicated by -999. (Source: Integrated Taxonomic Information System)

    Source
    Original source of the data

    Org
    Affiliation of the group who originally collected the data

    Method
    Method of isotopic ratio sample collection and measurement. (Source: Data collector)

    Citation
    Reference citations from data in this dataset. (Source: Originator)

    SampleType
    Broad category for the type of sample, e.g., benthic. (Source: Originator)

    Taxon
    Entity sampled (Source: Data collector)

    FeedGuild
    Feeding Guild by Macdonald, et. al., 2010. Key: PEL: Pelagic EP: Epibenthic SR: Surface SS: Sub-surface He: Herbivore De: Detritovore Su: Suspension feeder Pr: Predator mac: macrofauna mei: meiofauna zoo: zooplankton (Source: Macdonald, TA, BJ Burd, VI Macdonald, A. van Roodsellar. 2010. Taxonomic and feeding guild classification for the marine benthic macroinvertebrates of the Strait of Georgia, British Columbia. Canadian Technical Report of Fisheries and Aquatic Sciences 2874. Fisheries and Oceans Canada.)


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    This dataset was compiled from a variety of sources by Ken Dunton, Marine Science Institute, The University of Texas at Austin. Data were loaded into a GIS feature class by Tim Whiteaker, Center for Research in Water Resources, The University of Texas at Austin.

  3. To whom should users address questions about the data?

    Marine Science Institute, The University of Texas at Austin
    Attn: Ken Dunton
    Professor

    1-361-749-6744 (voice)
    ken.dunton@utexas.edu


Why was the data set created?

To synthesize carbon and nitrogen stable isotope data from several studies into a single dataset, with a focus on data in the Pacific-influenced coastal shelf ecosystem of the Arctic Ocean.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

  3. What similar or related data should the user be aware of?


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Accuracy data is not available for this dataset.

  2. How accurate are the geographic locations?

    Station locations generally appear accurrate when overlain onto regional scale maps.
    Points from the following CruiseIDs initially plotted far inland, suggesting coordinates are off. The locations were moved as described below. The original latitude and longitude values were not changed in the attribute table, thereby preserving a record of the original coordinates as supplied by the data source.
    CruiseID Golikov Russia 1989 ''''''''''''''''''''''''''''
    Sites: Amguyema River Kolyachinskaya Bay - inside Kolyachinskaya Bay - outside
    Note: Golikov's Wrangel Island locations seem correct
    These sites were moved per instructions from Susan Schonberg as follows, using ETOPO1 to provide depths: The inside Kolyachinskaya Bay is in the center of the bay near the coast. Adding a negative sign to the longitude places the point in that location, so the new coordinates are (-174.167, 66.9). The outside Kolyachinskaya Bay is located off the western coast in 30 m depth. Like the previous point, adding a negative sign to the longitude places the point in the rightlocation, (-174.5, 67.767). The Amguyema River is located against the river at 50 m depth. Negative sign was missing again. Correct coordinates (-177.5, 68.6)
    Cruise ID NP 1994 '''''''''''''''''
    Site: NP94 (168.83, 67.75)
    There is only one other NP94 site in the dataset. It has the same longitude as the suspect site, but different latitude. Assume the latitude in the suspect site is wrong, and use the same latitude as the other NP94 site, 73.5. Cruise ID RV Thompson 1988 ''''''''''''''''''''''''''
    Site: R/V THOMAS WASHINGTON - TW88 (163.12, 67.03)
    The other sites in this cruise are located in the Bering Strait. Longitude of this site of 163.12 is also -196.88 (the originally reported longitude). Assuming a typo, a longitude of -169.88 places this site between the two sites with the most similar latitude. With nothing else to help locate this site, assuming there was a typo and correcting the longitude to be -169.88 seems reasonable.

  3. How accurate are the heights or depths?

    Vertical accuracy is not available for depths reported in this dataset.

  4. Where are the gaps in the data? What is missing?

    Data in the original source datasets east of -120 degrees longitude or south of 60 degrees north latitude were excluded from this dataset. Sites on land or in inland waters were also excluded.
    Some data points from collectors Golikov and Haubenstauk included coordinates placing those points in what appeared to be incorrect locations (far inland in Russia). These points were excluded from the dataset.

  5. How consistent are the relationships among the observations, including topology?

    This synthesis dataset relies heavily on quality control performed by original data collectors. However, all stable isotope ratio values do fall within a reasonable range of values.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
Station locations are publicly available. Stable isotope values are restricted for use within the PacMARS research team. Data will be made available to the public after the first year of the PacMARS project.
The publisher, originator, original data collectors, and others associated with this work assume no liability for the quality and use of this dataset.
Use_Constraints:
PacMARS team members should be contacted before use of their data sets. PacMARS investigators and others are responsible for providing appropriate recognition to data providers in publications. This can include article co-authorship and/or reference to data publications. Citations, and DOIs when available, will be provided for datasets within the EOL data archive.

  1. Who distributes the data set? (Distributor 1 of 1)

    National Center for Atmospheric Research
    Attn: Earth Observing Laboratory
    3450 Mitchell Lane
    Boulder, CO 80301
    USA

    303-497-8154 (voice)
    codiac@ucar.edu

  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    PacMARS team members should be contacted before use of their data sets. PacMARS investigators and others are responsible for providing appropriate recognition to data providers in publications. This can include article co-authorship and/or reference to data publications. Citations, and DOIs when available, will be provided for datasets within the EOL data archive.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    Data can be obtained from EOL, <http://www.eol.ucar.edu/>.


Who wrote the metadata?

Dates:
Last modified: 29-May-2013
Metadata author:
The University of Texas at Austin
Attn: Tim Whiteaker
Research Associate
10100 Burnet Rd., Bldg. 119
Austin, TX 78758
USA

512-471-0570 (voice)
twhit@mail.utexas.edu

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


This page is <http://pacmars.eol.ucar.edu/docs/metadata/stable_isotope_synthesis_metadata.faq.html>
Generated by mp version 2.9.23 on Thu Jan 2 10:25:52 2014