Identification_Information:
  Citation:
    Citation_Information:
      Originator:
        Charles W. Holmes (retired)

        Debra Willard
      Publication_Date: 1999
      Title: Florida Bay Physical Data
      Geospatial_Data_Presentation_Form: spreadsheet
      Online_Linkage: http://sofia.usgs.gov/exchange/holmes/holmesradiochem.html
  Description:
    Abstract:
      The dataset contains the core number, depth (cm), wet bulk density,
      dry bulk density, accumulated dry bulk density, dry bulk fines, total
      % H2O content, % insoluble residue, % loss on ignition, coarse (% dry
      wt.) > 0.062 mm, fines (% dry wt.) < 0.062 mm, and total Pb-210
      activity (dpm/g and error).
    Purpose:
      The use of radioactive isotopes is founded on the known physical
      property of radioactive material, the half-life. A half-life of an
      isotope is the amount of time it takes for half of a given number of
      atoms to "decay" to another element. The age of objects that contain
      radioactive isotopes with known half-lives can be calculated by
      determining the percent of the remaining radioactive material. To use
      this method successfully certain other prerequisites must be met.
      These are: 1. the chemistry of the nuclide (element) is known; 2. once
      the nuclide is incorporated into the substrate the only change is
      radioactive decay, and 3. in order to be useful, it is relatively easy
      to measure.
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 19940224
        Ending_Date: 19970613
    Currentness_Reference: ground condition
  Status:
    Progress: complete
    Maintenance_and_Update_Frequency: none planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -81.75
      East_Bounding_Coordinate: -80.1
      North_Bounding_Coordinate: 26.5
      South_Bounding_Coordinate: 24.75
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: core depth
      Theme_Keyword: Radioactive isotopes
      Theme_Keyword: total Pb-210
      Theme_Keyword: geology
      Theme_Keyword: geochemistry
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: environment
      Theme_Keyword: geoscientificInformation
      Theme_Keyword: inlandWaters
      Theme_Keyword: 007
      Theme_Keyword: 008
      Theme_Keyword: 012
    Place:
      Place_Keyword_Thesaurus:
        Department of Commerce, 1995, Countries, Dependencies, Areas of
        Special Sovereignty, and Their Principal Administrative Divisions, 
        Federal Information Processing Standard (FIPS) 10-4, Washington,
        D.C., National Institute of Standards and Technology
      Place_Keyword: United States
      Place_Keyword: US
    Place:
      Place_Keyword_Thesaurus:
        U.S. Department of Commerce, 1987, Codes for the identification of
        the States, the District of Columbia and the outlying areas of the
        United States, and associated areas (Federal Information Processing
        Standard 5-2): Washington, D. C., NIST
      Place_Keyword: Florida
      Place_Keyword: FL
    Place:
      Place_Keyword_Thesaurus:
        Department of Commerce, 1990, Counties and Equivalent Entities of
        the United States, Its Possessions, and Associated Areas, FIPS 6-3,
        Washington, DC, National Institute of Standards and Technology
      Place_Keyword: Collier County
      Place_Keyword: Miami-Dade County
      Place_Keyword: Monroe County
    Place:
      Place_Keyword_Thesaurus: USGS Geographic Names Information System
      Place_Keyword: Rabbit Key
      Place_Keyword: Cluett Key
      Place_Keyword: Whipray Basin
      Place_Keyword: Bob Allen Key
      Place_Keyword: Lake Ingraham
      Place_Keyword: Johnson Key
      Place_Keyword: Porjoe Key
      Place_Keyword: Trout Creek
      Place_Keyword: Little Madeira Bay
      Place_Keyword: Crocodile Point
      Place_Keyword: Pass Key
      Place_Keyword: Florida Bay
      Place_Keyword: Rankin Bight
    Place:
      Place_Keyword_Thesaurus: none
      Place_Keyword: Central Everglades
      Place_Keyword: SW Big Cypress
      Place_Keyword: Russell Bank
  Access_Constraints: none
  Use_Constraints: none
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Debra A Willard
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: mailing address
        Address: 926A National Center
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
      Contact_Voice_Telephone: 703 648 5320
      Contact_Facsimile_Telephone: 703 648 6953
      Contact_Electronic_Mail_Address: dwillard@usgs.gov
  Native_Data_Set_Environment: MS Excel spreadsheets
Data_Quality_Information:
  Logical_Consistency_Report: not applicable
  Completeness_Report:
    Data is available for sites 3b (Rabbit Key), 5g (Whipray Basin), 6a and
    6c (Bob Allen Key), 7b (Rankin Bight), 8b (Lake Ingraham), 10b (Russell
    Bank S), 11a (Johnson Key), 12b and 12d (Porjoe Key), 13a (Trout Creek),
    14b (Little Madeira Bay), 16b (Crocodile Point), 17d and 17g (Pass Key),
    18c (Russell Bank N), 19b and 19c (Russell Bank S), 20d (Bob Allen Key),
    21b (Pass Key Bank), 21e (Pass Key Bank-North), 21f (Pass Key Bank
    -South), 22d (Russell Bank South), 23a (Park Key Bank), 24a and 24c (Bob
    Allen Key Bank), 25b (Whipray Basin), 26-35 and 26-37 (Pass Key Bank)
  Lineage:
    Process_Step:
      Process_Description:
        Analytical

        Major Sediment Characteristics

        In the laboratory, the bagged samples were first weighed to
        determine the water loss. A wet aliquot was placed in pre-cleaned
        pre-weighed porcelain evaporating dish, dried at 40 deg. C, cooled
        and re-weighed to determine water loss. This sample was dissolved in
        6N HCl. The filtrate was washed three times with distilled water and
        dried. The residue was reweighed and reported as percent insoluble
        residue.

        A separate aliquot (ca. 20 g wet weight) was weighed then sieved (62
        micron mesh) using distilled water to obtain the amount of fine
        sediment in each interval. These samples were freeze-dried. Portions
        of dried samples were ground to a fine powder (75-100 mesh) in a
        grinding mill to obtain a homogeneous sample for analysis. Sample
        splits were made and 5g placed into pre-cleaned, pre-weighed
        crucibles and heated in a muffle furnace at 450 deg. for 6 hours so
        as to obtain a stable weight. The samples were then cooled and
        reweighed to determine loss on ignition.  The remain fraction was
        submitted for 210Pb analysis.

        Total extracted lead-210

        The analysis of sediments at the USGS-Denver is based on counting of
        Po-210, in secular equilibrium with its parent Pb-210, and exploits
        the ability of polonium to self-plate onto silver and certain other
        metals (FLYNN, 1968). Five grams of the >62 micrometer dried, ground
        sample was transferred to a 100 ml Teflon beaker and mixed with 5-10
        ml of reagent grade 16N nitric acid. An amount of NIST-calibrated
        Po-209 spike was added and the sample swirled to mix the spike. The
        beaker was covered with a watch glass and allowed to stand
        overnight. The solution with solids was allowed to evaporate under
        heat lamps at 90 deg. C. The sample was washed from the sides of the
        beaker using 8N Hydrochloric acid and swirled again to insure proper
        mixing. The solution is evaporated again and allowed to cool. One ml
        of 30% hydrogen peroxide was then added to the sample and the
        resulting mixture evaporated to dryness. These latter steps, adding
        peroxide and drying the mixture were repeated an additional two
        times. The 8N HCl was added to the sample and allowed to dry out. 
        This step was repeated so as to ensure that nitric acid, which
        hinders efficient plating is virtually eliminated from the mixture.
        Finally 5ml of 8N HCl were added to the dried sample and the mixture
        transferred to a 100ml beaker using additional amounts of de-ionized
        water to insure essentially complete transfer.  To minimize
        interference of several ions with plating, 5ml of hydroxylamine
        hydrochloride and 2ml of 25% sodium citrate were added to each
        sample.  Additionally, 1ml of a hold back carrier, bismuth nitrate,
        was added to prevent deposition of Bi-212.   A plastic coated
        magnetic bar was added to each beaker for stirring during
        autoplating. The pH of the solution was adjusted to between 1.85 and
        1.95 using ammonium hydroxide. The beaker was placed on a hot plate
        and heated between 85 and 90 deg. C for 5 minutes to reduce iron,
        chromium and oxidants present. Then a Teflon holder which exposes
        one side of a silver foil disc was placed in the solution for a
        minimum of 90 minutes. Rinsed and air-dried silver discs were then
        counted for polonium isotopes by alpha spectroscopy. Combined
        analytical and counting errors in determining lead-210 values are
        about 3%.

        For purposes of intercalibration, fifteen samples of sieved sediment
        (from Bob Allen Core 6C) were analyzed at the GLERL laboratory for
        lead-210 by counting its decay product, polonium-210. Two gram
        samples were placed in beakers, 1 ml of calibrated polonium-209
        standard solution added to each, followed by 30 ml of concentrated
        HCl transferred slowly to avoid excessive foaming. After subsidence
        of foaming (in 24 hrs) the mixtures were placed in centrifuge tubes
        and allowed to stand for two weeks at room temperature. The mixture
        was then centrifuged and the supernatant decanted. The residue was
        rinsed, re-centrifuged and the second aliquot of supernatant added
        to the first. The above procedure was then repeated on the rinsed
        residue with the additional step of first slowly adding 10 ml of 30%
        hydrogen peroxide to oxidize organic matter and presumably release
        any bound lead-210 into the extractant. To both sets of supernatant
        solutions, one gram of NH2OH&uacute;HCl was added as in the Denver
        method to reduce the interference of dissolved iron with polonium
        plating (FLYNN, 1968) and the solutions brought to a volume of 100
        ml with distilled water and adjusted to a pH of 1.5 via small
        additions of NH4OH.  Polonium isotopes were self-plated onto
        polished, Mylar-backed copper disks placed in the solutions (at 85
        C) and gently agitated for eight hours. Exposed disks were
        alcohol-rinsed and counted by alpha spectrometers consisting of
        surface barrier detectors coupled to a multichannel analyzer. The
        polonium-209 solution was calibrated by comparison with standard
        solutions of polonium-208 (NIST SRM 4327) and with polonium-210 in
        secular equilibrium with lead-210 in an NIST-traceable standard
        solution obtained from the U. S. Environmental Protection Agency
        (Environmental Monitoring Systems, Las Vegas, Nevada).  The activity
        of the polonium-208 solution has an overall uncertainty of 1.4
        percent. The activity of the polonium-209 solution is consistently
        determined by the two independent methods and presently known with
        an overall uncertainty of about 2.5%. Uncertainty due to random
        errors decreases in time because the activity of the solution is
        re-checked every few years by intercomparison with new
        NIST-traceable aliquots of polonium-208. Overall uncertainty in
        counting were about 2%.

        Total lead-210 and radium-226

        A larger aliquot of wet sediment was washed through a 62 micron
        stainless steel sieve using distilled water. The fine fraction was
        allowed to settle, overlying water decanted and the final slurry was
        freeze-dried and disaggregated. At USGS-Woods Hole, 10-50 grams of
        the freeze-dried fraction were transferred to a plastic counting jar
        with a tight sealing plastic screw cap. Sealed counting jars were
        stored for at least 20 days to allow for the in-growth of radium-222
        and lead-214 to approximate equilibrium values.

        Samples were counted on a gamma detector system consisting of a
        germanium detector for low energy gamma rays (2000 mm2 area) and a
        4096 channel multichannel analyzer. Samples were typically counted
        for 48 hours (depending on sample size) or until counting errors
        were <5%. The system has been calibrated using EPA standard
        pitchblende ore in the same geometry as the samples. A
        self-absorption correction (CUTSHALL et al., 1983) has been applied
        to each sample. Results of the lead-214 analysis (for radium-226) of
        the Canadian ore standard DH-1a were within 3.5% of the published
        value. Total lead-210 results on the same standard were 1952
        &ntilde;14 dpm/g (n=2) compared with the published value of 1848
        &ntilde;54 dpm/g, a 5.6 % difference.

        At the GLERL laboratory radium-226 was determined on 4.00
        &ntilde;0.02 g of dry, desegregated sediment less than 62
        micrometer.  Samples were packed into counting vials to a constant
        height 4.0 &ntilde;0.05 cm to assure a fixed counting geometry and
        packing density. Vials were sealed with epoxy cement and stored for
        at least three weeks to allow for in-growth of radon-222 and its
        gamma-emitting progeny.  Samples were placed in an intrinsic (HpGe)
        well detector and counted for up to two days to achieve acceptable
        counting statistics.  Specific activity of radium-226 was determined
        from counts associated with the gamma photopeaks of Pb-214 (295 and
        351 keV) and Bi-214 (609 KeV). Activities calculated from the three
        peaks were combined to yield a weighted mean reported value and
        standard deviation. The system was calibrated and frequently
        recalibrated by counting standards prepared by doping portions of
        Bay sediment with precisely known amounts of a radium standard
        solution (NIST SRM-4959). This solution has a 0.4% uncertainty in
        activity at the 99% confidence level due to random errors and an
        additional 0.8% uncertainty due to assessable systematic errors. 
        Reported standard deviations in radium activity, including random
        errors associated with detector calibration, were typically 5-7%.
        The limit of detection was about 0.1 dpm/g for this matrix.

        Total cesium-137

        The GLERL well and planar detectors were also calibrated for
        cesium-137 using sediment doped with a standard gamma-emitting,
        mixed radionuclide standard (Amersham Searle, QCY.46) traceable to
        the British Calibration Service. The system efficiency has also been
        calibrated using several NIST standard reference materials,
        (SRM-4354, Standard Lake Sediment; SRM-4353 Rocky Flats soil Number
        1 ; SRM-4353, River Sediment). In order to achieve acceptable
        counting statistics, all samples having significant radiocesium
        activity on the 1 to 2 day count for radium were recounted for up to
        five days each. The resulting overall detection limit was about 0.02
        dpm/g corresponding to a minimum uncertainty in reported activities
        of about 10%. Cesium-137 was also determined at USGS-Woods Hole on
        selected samples by counting the 661.7 KeV gamma ray.  Results for
        IAEA Standard 4018 were within 3% of published values. The detection
        limit was also about 0.02 dpm/g.

        Trace metal analysis (lead and others)

        To determine concentrations of selected trace metals (lead, uranium,
        barium and mercury) 0.2 grams of freeze-dried whole sediment from
        Bob Allen 6A, 6C and Russell Bank 19C were placed in microwave
        digestion vessels to which was added 20 ml of 10% Ultrapure nitric
        acid. The mixtures were processed by microwave digestion at 160 deg.
        C for 1 hour.  Ten ml of the resulting solutions were diluted 2.5x
        and analyzed for metals using an ICP-M system (Perkin Elmer Elate
        5000A) focused to detect Pb-208 and U-238. The system, situated in a
        class 100 laboratory, was calibrated linearly using standard
        concentrations of 1, 10 and 100 ppb of lead and uranium and checked
        using synthetic water reference (NIST-1643C) as the external
        standard.  Long term replication of that standard indicated a
        probable uncertainty in the determination of both metals as less
        than or equal to 5%. Concentrations of uranium reported as ppb were
        re-calculated in terms of specific activities (dpm/g) for comparison
        with lead-210 and radium-226 results.

        Isolation of the Non-Carbonate Fraction

        Starting from the top of core Bob Allen 6C, roughly equal weights of
        dried, sieved sediment from 10 contiguous 2 cm sections of core were
        combined to form a composite sample weighing 65 g spanning a 20 cm
        segment. Eight such composite samples were prepared for each 10
        successive 2-cm intervals downcore which together spanned the entire
        160 cm length of the core.  Four grams of each ground, homogenized
        composite was packed into standard vials and sealed for later
        counting while a 60g sample was placed in a 8 L container to which a
        stochiometric excess of dilute (10%) acetic acid was added to
        dissolve carbonates. Following the primary phase of gas evolution,
        the entire mixture was quantitatively transferred to large beakers,
        the solids allowed to settle and the supernatant decanted. Fresh 10%
        acetic acid was added along with a magnetic stirring bar. The
        mixtures were stirred continuously at ambient temperature (ca 20
        deg. C) for an additional three days to ensure complete dissolution
        of carbonates. Subsequently, the mixtures were allowed to settle,
        the supernatant discarded and residues rinsed with distilled water
        three times to remove soluble products.  Following drying, 4 grams
        of each residue were packed into standard vials and sealed for
        subsequent gamma counting.
      Process_Date: 1999
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Debra A Willard
            Contact_Organization: U.S. Geological Survey
          Contact_Address:
            Address_Type: mailing address
            Address: 926A National Center
            City: Reston
            State_or_Province: VA
            Postal_Code: 20192
          Contact_Voice_Telephone: 703 648 5320
          Contact_Facsimile_Telephone: 703 648 6953
          Contact_Electronic_Mail_Address: dwillard@usgs.gov
Spatial_Data_Organization_Information:
  Indirect_Spatial_Reference: Florida Bay
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Geographic:
      Latitude_Resolution: 0.0001
      Longitude_Resolution: 0.0001
      Geographic_Coordinate_Units: Decimal degrees
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137
      Denominator_of_Flattening_Ratio: 298.257
Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview:
      The attributes for each site are: core no., depth in cm, wet bulk
      density (g/cm3), dry bulk density (g/cm3), accum. Dry bulk density
      (g/cm3), dry bulk fines density (g/cm3), total % h20 content, insol.
      residue (%dry wt.), loss on ignition (% dry wt.), coarse (%dry wt.)
      >0.062mm, fines (%dry wt.) <0.062 mm, total Pb-210 activity (dpm/g),
      and total Pb-210 activity error (+/_)
    Entity_and_Attribute_Detail_Citation: USGS personnel
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Heather S.Henkel
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: mailing address
        Address: 600 Fourth St. South
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727 803-8747 ext 3028
      Contact_Facsimile_Telephone: 727 803-2030
      Contact_Electronic_Mail_Address: hhenkel@usgs.gov
  Resource_Description: Florida Bay physical data
  Distribution_Liability: The data have no implied or explicit guarantees
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: MS Excel
        Format_Version_Date: 1997
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: http://sofia.usgs.gov/exchange/holmes/holmesradiochem.html
          Access_Instructions: Data may be downloaded from the SOFIA website
    Fees: none
Metadata_Reference_Information:
  Metadata_Date: 20071031
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Heather Henkel
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 600 Fourth Street South
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727 803-8747 ext 3028
      Contact_Facsimile_Telephone: 727 803-2030
      Contact_Electronic_Mail_Address: sofia-metadata@usgs.gov
  Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998