Collection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015

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What does this data set describe?

Title:
Collection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015
Abstract:
Coastal wetlands in Tampa Bay, Florida, are important ecosystems that deliver a variety of ecosystem services. Key to ecosystem functioning is wetland response to sea-level rise through accumulation of mineral and organic sediment. The organic sediment within coastal wetlands is composed of carbon sequestered over the time scale of the wetland’s existence. This study was conducted to provide information on soil accretion and carbon storage rates across a variety of coastal ecosystems that was utilized in the Tampa Bay Blue Carbon Assessment (ESA, 2017; linkage below). Ten sediment cores were collected from six Tampa Bay wetland sites in October 2015 (maximum core length 40 centimeters). Three main vegetation types were targeted for core collection: salt marsh, dominated by Juncus and Spartina alternaflora; mangrove, including Rhizophora mangle, Laguncularia racemosa and/or Avicennia germinans; and young mangrove, where wetlands were created within the last three decades. An additional surface sediment sample was collected from a salt barren, as this site was not conducive to coring. Marsh surface elevations were measured at each site (ranging from 0.771 meters to 1.462 meters relative to NAVD88) to determine the marsh boundaries within current tidal conditions. Continuous Rate of Supply age models, based on lead-210 and cesium-137 isotope analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. Over that time, accretion rates were very similar for each ecosystem: restored marsh sites (2.5 mm per year), followed by the salt marshes (2.7 mm per year) and mature mangroves (3.2 mm per year). The resulting carbon burial rates over the past century vary as a function of vegetation type, with mature mangroves burying on average 163 grams carbon per square meter per year, compared to young (restoring) mangroves with an average of 94 grams carbon per square meter per year and the salt marsh with an average of 64 grams carbon per square meter per year . This dataset also includes dry bulk density (0.02 - 1.70 grams per cubic centimeter), percent carbon (0.32 %-39.08 %), and percent loss on ignition (0.66 % – 80.2 %) from a sub-set of core sections in order to assess possible correlative relationships among these parameters.
https://estuaries.org/wp-content/uploads/2019/02/FINAL_Tampa-Bay-Blue-Carbon-Assessment-Report-updated-compressed.pdf
Supplemental_Information:
For more information, see the following field activity: https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-071-FA
  1. How might this data set be cited?
    O'Keefe Suttles, Jennifer A., Eagle, Meagan J., Mann, Adrian G., Smith, Chris, and Kroeger, Kevin D., 20210630, Collection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015: data release DOI:10.5066/P9QB17H2, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: O’Keefe Suttles, J.A., Eagle, M.J., Mann, A.G., Smith, C.G., Kroeger, K.D., 2021, Collection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015: U.S. Geological Survey data release, https://doi.org/10.5066/P9QB17H2
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -82.71587
    East_Bounding_Coordinate: -82.46762
    North_Bounding_Coordinate: 28.0076
    South_Bounding_Coordinate: 27.58085
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/60bfb8a4d34e86b938916d6f?name=TampaBay_Wetland.jpg (JPEG)
    Browse graphic is a photograph of a Juncus marsh in the Tampa Bay estuary, Florida.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 19-Oct-2015
    Currentness_Reference:
    Ground Condition. These are the dates when the cores were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Tabulated comma separated text file (.CSV)
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Geographic Names Information System (GNIS) placenames are included as keywords to give the general location of core collections. The entity contains attributes with specific latitude and longitude of each core collection; several attributes are also included to describe the core collection location: nearest body of water, vegetation type, and in some cases, the nearest road. Refer to the entity and attribute definitions for "Site", "Status", and "ID" for details.
      This is a Point data set.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 1.0E-5. Longitudes are given to the nearest 1.0E-5. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Data_TampaBay_Cores.csv
    Comma separated text file with soil core data collected from salt marsh and mangrove sites within the Tampa Bay estuary. The file includes latitude and longitude of core collection, calculated values of soil dry bulk density, mass accumulation rates, vertical accretion rates, and carbon burial rates. Also included are the data required for those calculations: radioisotope data, soil carbon and nitrogen content. The dataset includes 277 records. (Source: Producer-defined)
    Site
    A text identifier for the general location of the study site within Tampa Bay. (Source: Producer-defined)
    ValueDefinition
    E.G. SimmonsA data point from a sediment core collected within a wetland at E.G. Simmons Park (Ruskin, Florida).
    Fort de SotoA data point from a sediment core collected within a wetland at Fort de Soto Park, (St. Petersburg, Florida).
    Holly HouseA data point from a sediment core collected within a wetland at Terra Ceia Preserve State Park, (Palmetto, Florida). Note that a nearby landmark is named Haley House, however, our field notes refer to the location as Holly House.
    Rocky CreekA data point from a sediment core collected within a wetland along Rocky Creek (Tampa, Florida).
    Upper Tampa BayA data point from a sediment core collected within a wetland in the Upper Tampa Bay region (Tampa, Florida).
    Weedon IslandA data point from a sediment core collected within a wetland at Weedon Island Preserve, (St. Petersburg, Florida).
    Status
    A text identifier indicating the vegetation type that now dominates the sediment core collection site. (Source: Producer-defined)
    ValueDefinition
    MangroveData point collected from a location dominated by mature mangrove vegetation.
    Juncus MarshData point collected from a location that is now dominated by Juncus salt marsh vegetation.
    Salt BarrenData point collected from a location without much vegetation cover although it may be adjacent to a vegetated area.
    Young MangroveData point collected from a study site that has had a wetland created in the last three decades and the established mangrove trees are relatively young.
    ID
    Abbreviated alphabetical identification code of each core to indicate the study site from which it was collected using a two or three letter abbreviation; an additional qualifier of A or B was added to abbreviations for E.G. Simmons, Holly House, and Rocky Creek to differentiate replicate cores. Note, replicate cores were only collected from those three sites. Cores collected from Upper Tampa Bay (UT) represent two different ecosystems - a salt barren and a salt marsh. Refer to the attribute "Status" for further site details. (Source: Producer-defined)
    ValueDefinition
    EGSAE.G. Simmons, core A
    EGSBE.G. Simmons, core B
    FDSFort de Soto
    HHMAHolly House, Mangrove, core A
    HHMBHolly House, Mangrove, core B
    RCRARocky Creek, core A
    RCRBRocky Creek, core B
    UTRUpper Tampa Bay
    UTSBUpper Tampa Bay, Salt Barren
    WIWeedon Island
    Date
    A numeric identifier of the date the core was collected in the format of month/day/year. (Source: Producer defined)
    Range of values
    Minimum:10/19/2015
    Maximum:10/21/2015
    Units:mm/dd/yyy
    Lat
    Latitude decimal degrees north, NAD83 (Source: Producer-defined)
    Range of values
    Minimum:27.580827
    Maximum:28.007596
    Units:decimal degrees
    Lon
    Longitude decimal degrees west, NAD83. The negative value indicates a location in the western hemisphere. (Source: Producer-defined)
    Range of values
    Minimum:-82.715883
    Maximum:-82.467600
    Units:decimal degrees
    Depth_mid
    A numeric identifier of the interval mid-point depth below the sediment interface in centimeters. (Source: Producer-defined)
    Range of values
    Minimum:0.5
    Maximum:39.5
    Units:centimeters
    Elevation
    A numeric identifier of interval mid-point elevation relative to NAVD88 datum in centimeters. Calculated by subtracting the sample mid-interval depth from the NAVD88 land surface elevation of the core location. Refer to the vertical accuracy report within this metadata record for elevation accuracy estimates for each site. (Source: Producer-defined)
    Range of values
    Minimum:-100.6
    Maximum:145.7
    Units:centimeters
    DBD
    Dry Bulk Density: A numeric identifier of the sediment dry bulk density in grams per cubic centimeter (g/cm3). Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:0.0244
    Maximum:1.6953
    Units:grams per cubic centimeter
    210Pb
    A numeric identifier of the sediment total lead-210 activity in decays per minute per gram (dpm/g). Measured at 46.5 kiloelectronvolt (KeV) on a planar gamma counter. Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection; see gamma analysis process step for detection limits of radioisotopes. (Source: Producer-defined)
    Range of values
    Minimum:0.2681
    Maximum:10.7749
    Units:decays per minute per gram
    210Pb_e
    A numeric identifier of the measurement error in sediment total lead-210 activity in decays per minute per gram (dpm/g). Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. (Source: Producer-defined)
    Range of values
    Minimum:0.0278
    Maximum:0.8670
    Units:decays per minute per gram
    226Ra
    A numeric identifier of the sediment total radium-226 activity in decays per minute per gram (dpm/g). Measured at 352 kiloelectronvolt (KeV) on a planar gamma counter. Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection; see gamma analysis process step for detection limits of radioisotopes (Source: Producer-defined)
    Range of values
    Minimum:0.1547
    Maximum:6.6989
    Units:decays per minute per gram
    226Ra_e
    A numeric identifier of the measurement error in sediment total radium-226 activity in decays per minute per gram (dpm/g). Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. (Source: Producer-defined)
    Range of values
    Minimum:0.0995
    Maximum:0.2928
    Units:decays per minute per gram
    210Pbex
    A numeric identifier of the sediment excess lead-210 activity in decays per minute per gram (dpm/g). Calculated as the difference between total lead-210 and total radium-226 activities. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:-0.5091
    Maximum:9.5208
    Units:decays per minute per gram
    210Pbex_e
    A numeric identifier of the propagated measurement error in sediment excess lead-210 activity in decays per minute per gram (dpm/g). Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:0.0294
    Maximum:0.9151
    Units:decays per minute per gram
    137Cs
    A numeric identifier of the sediment total cesium-137 activity in decays per minute per gram (dpm/g). Measured at 662 kiloelectronvolt (KeV) on a planar gamma counter. Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection; see gamma analysis process step for detection limits of radioisotopes. (Source: Producer-defined)
    Range of values
    Minimum:0.0070
    Maximum:0.9950
    Units:decays per minute per gram
    137Cs_e
    A numeric identifier of the measurement error in sediment total cesium-137 activity in decays per minute per gram (dpm/g). Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. (Source: Producer-defined)
    Range of values
    Minimum:0.0069
    Maximum:0.0800
    Units:decays per minute per gram
    7Be
    A numeric identifier of the total sediment beryllium-7 activity in decays per minute per gram (dpm/g). Measured at 477 kiloelectronvolt (KeV) on a well gamma counter. The value 0.00 is given to analyzed samples found to be below detection; see gamma analysis process step for detection limits of radioisotopes. (Source: Producer-defined)
    Range of values
    Minimum:0.7100
    Maximum:18.40
    Units:decays per minute per gram
    7Be_e
    A numeric identifier of the measurement error in sediment total beryllium-7 activity in decays per minute per gram (dpm/g). Blank/empty cells indicate the measurement was not done. The value 0.00 is given to analyzed samples found to be below detection. (Source: Producer-defined)
    Range of values
    Minimum:0.1500
    Maximum:3.0700
    Units:decays per minute per gram
    wtC
    Total amount of organic carbon by weight percent in soil. Sediments in this sample set were placed in a acid fuming desiccator to remove inorganic carbon prior to analysis. Blank/empty cells indicate the measurement was not done. Refer to the attribute accuracy and process step sections for further details. (Source: Producer-defined)
    Range of values
    Minimum:0.32
    Maximum:39.08
    Units:unitless
    wtN
    Total amount of organic nitrogen by weight percent in soil. Sediments in this sample set were placed in a acid fuming desiccator to remove inorganics prior to analysis. Blank/empty cells indicate the measurement was not done. Refer to the attribute accuracy and process step sections for further details. (Source: Producer-defined)
    Range of values
    Minimum:0.01
    Maximum:1.77
    Units:unitless
    Age
    Age: A numeric identifier for the age in years from the collection date of the core interval based on the Continuous Rate of Supply lead-210 age model. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:1.1
    Maximum:104.9
    Units:years
    Age_e
    Age_e: A numeric identifier for the age model uncertainty in years of the core interval based on the Continuous Rate of Supply lead-210 age model. Error is propagated through the model. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:0.90
    Maximum:40.5
    Units:years
    VAR
    Vertical Accretion Rate: A numeric identifier for the vertical accretion rate of the sediment in millimeters per year (mm/y). Calculated as the difference in interval midpoint divided by the difference in ages of those adjacent sediment intervals. (Source: Producer-defined)
    Range of values
    Minimum:0.7
    Maximum:8.8
    Units:millimeters per year
    MAR
    Mass Accumulation Rate: A numeric identifier for the mass accumulation rate of the sediment in grams per square meter per year (g/m2/y). Calculated by multiplying dry bulk density times vertical accretion rate. (Source: Producer-defined)
    Range of values
    Minimum:112
    Maximum:4458
    Units:grams sediment per square meter per year
    CAR
    Carbon Accumulation Rate: A numeric identifier for the carbon mass accumulation rate of the sediment in grams of carbon per square meter per year (gC/m2/y). Calculated by multiplying the average mass accumulations rate for the combined depth interval of the elemental sample times weight percent carbon. (Source: Producer-defined)
    Range of values
    Minimum:6
    Maximum:378
    Units:grams carbon per square meter per year
    Year
    The year corresponding to the soil horizon based on the Continuous Rate of Supply (CRS) lead-210 age model. Calculated as collection date minus age of sediment at each depth interval. Year is not calculated for deeper sections that are beyond the limits of the CRS model. (Source: Producer-defined)
    Range of values
    Minimum:1911.0
    Maximum:2014.8
    Units:calendar year
    LOI
    LOI: Loss On Ignition is the amount of material lost when sediment is burned in a muffle furnace for 4 hours at 450 degrees Celsius. Percent LOI is an operationally defined proxy estimate for the amount of organic matter (and organic carbon) content. (Source: Producer-defined)
    Range of values
    Minimum:0.6559
    Maximum:80.1975
    Units:percent

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • O'Keefe Suttles, Jennifer A.
    • Eagle, Meagan J.
    • Mann, Adrian G.
    • Smith, Chris
    • Kroeger, Kevin D.
  2. Who also contributed to the data set?
    Field work was supported by Dr. Ryan Moyer’s team at the Florida Fish and Wildlife Institute, St. Petersburg, FL. Dr. Nicole Khan provided laboratory and field assistance.
  3. To whom should users address questions about the data?
    Meagan J Eagle
    Northeast Region: WOODS HOLE COASTAL & MARINE SCIENCE
    Research Physical Scientist
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2280 (voice)
    meagle@usgs.gov

Why was the data set created?

Sediment cores were collected, age-dated, and their carbon content was measured to calculate vertical accretion and carbon burial rates. Data were collected to determine 1) carbon burial rates in typical Tampa Bay ecosystems and 2) the ecosystem resilience to sea-level rise.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 5)
    Sites around Tampa Bay were visited on October 19, 20 and 21, 2015 and sediment cores were collected. Three main vegetation types were targeted: salt marsh, dominated by Juncus and Spartina alternaflora; mangrove, including Rhizophora mangle, Laguncularia racemosa and/or Avicennia germinans; and young mangrove, where wetlands were created within the last three decades. E.G. Simmons park was restored in 1990 (Osland and others, 2012). An additional surface sediment sample was collected from a salt barren, as this site was not conducive to coring. USGS core collections were co-located with biomass and soil surveys conducted by study collaborators.
    Sediment cores were taken by pounding 4 inch diameter PVC pipe 20 to 40 cm into the ground. Compaction was monitored by measuring the sediment surface inside and outside the core tube. If compaction was greater than 1 cm (2-3% of total core length), the core was discarded and not used. After the core barrel was inserted into the sediment, a rubber gasket and handle were placed over the top and then the core was dug out of the sediment. The gasket allowed the core to be removed without further disturbance. Caps were placed on the top and bottom of each core immediately after collection. The cores were transported upright to the laboratory for further processing. At the salt barren site it was not possible to take a sediment core, so a section of sediment was removed with a shovel, sectioned and bagged in the field. Note at the two restored mangrove sites (E.G. Simmons and Fort de Soto) cores were collected of the organic peat above a compact sand layer, which was not conducive to coring. Thus these cores are only 20-24 cm deep, compared to other cores that were 30-40 cm deep.
    Latitude, longitude, and elevation were measured, by study collaborators, with a differential global positioning system (DGPS). Refer to the horizontal and vertical accuracy report sections of the metadata record for more information regarding this measurement. The process date reflects the last occurrence of the work.
    Osland, M.J., A.C. Spivak, J.A. Nestlerode, J.M. Lessmann, A.E. Almario, P.T. Heitmuller, M.J. Russell, K.W. Krauss, F. Alvarez, D.D. Dantin, J.E. Harvey, A.S. From, N. Cormier, C.L. Stagg. 2012. Ecosystem Development after mangrove wetland creation: Plant-soil change across a 20-year chronosequence: Ecosystems 15: 848-866, https://doi.org/10.1007/s10021-012-9551-1.
    Date: 2016 (process 2 of 5)
    All cores were transported to the U.S. Geological Survey in St. Petersburg, FL, the day of collection and immediately sectioned. Cores were sectioned on a spinning wheel, which was calibrated to push 1 cm of sediment out of the core top. This interval was removed, placed in a labeled whir-pak bag, weighed (wet weight) and frozen. Samples were shipped frozen overnight to the U.S. Geological Survey in Woods Hole, MA, where all further laboratory analysis was done. All sediment samples were kept frozen (-40 degrees Celsius) until freeze dried. Samples were kept in original sample bags and placed in a freeze dryer for 1 week until constant weight was achieved. Samples were immediately weighed (dry weight). Dry bulk density was determined as the dry weight of a known volume of sample.
    Approximately 5 g of dried sediment sample was blended and homogenized prior to sealing in a jar for a minimum of three weeks and then placed on a planar-type gamma counter for 24 to 48 hours to measure 7Be, 137Cs, 210Pb, and 226Ra at 477, 662, 46.5 and 352 kiloelectronvolts (KeV) energies respectively (Canberra Inc., USA). Detector efficiency was determined from EPA standard pitchblende ore in the same geometry as the samples. Activities of 7Be, 137Cs, and 210Pb were decay corrected to time of collection. Suppression of low energy peaks by self-absorption was corrected for according to Cutshall and others, 1983. Peak detection, with respect to background activity, is calculated for each radioisotope in the APTEC software during sample analysis. Generally, measured radioisotope activity greater than or equal to 0.30 (210Pb), 0.20 (226Ra), 0.71 (7Be), and 0.10 (137Cs) dpm/g were accepted as above detection limit for this dataset; values below are reported as 0. Sediment ages and accretion rates were calculated with the continuous rate of supply 210Pb age model, a variant on the advection-decay equation (Appleby and Oldfield, 1978; Goldberg, 1963). This model assumes that 210Pb supply to the sediment surface is constant through time, but allows for changing sedimentation rates, in addition to decay, to control the down-core activity of 210Pb. The common form of the CRS (constant rate of 210Pb supply) model as derived by Appleby and Oldfield (1978) solves for age based on the distribution of 210Pb in the sediment record. Prior to application of the age model, 210Pb profiles were evaluated to ensure they were sufficiently resolved to apply the CRS model without bias towards ages that are too old or accretion rates that are too low at depth (Binford, 1990). All gamma analyses were ongoing from 2015 and completed in 2016.
    Appleby, P.G., and Oldfield, F., 1978, The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sediment: Catena, v. 5, issue 1, p. 1–8, https://doi.org/10.1016/S0341-8162(78)80002-2.
    Binford, M.W., 1990, Calculation and uncertainty analysis of 210 Pb dates for PIRLA project lake sediment cores: Journal of Paleolimnology, v. 3, issue 3, p. 253-267, https://doi.org/10.1007/BF00219461.
    Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210 Pb in sediment samples—Self-absorption corrections: Nuclear Instruments and Methods in Physics Research, v. 206, issues 1–2, p. 309–312, https://doi.org/10.1016/0167-5087(83)91273-5.
    Goldberg, E.D, 1963, Geochronology with 210 Pb, in Miller, J.A., convener, Radioactive dating: International Atomic Energy Agency Symposium on Radioactive Dating, Athens, Greece, November 19-23, 1962, [Proceedings], p. 121-131. Person who carried out this activity:
    Meagan J Eagle
    Northeast Region: WOODS HOLE COASTAL & MARINE SC
    Research Physical Scientist
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2280 (voice)
    meagle@usgs.gov
    Date: 2016 (process 3 of 5)
    A subsample of freeze-dried sediment (0.5 g) was ball-milled to a fine powder and packaged for carbon and nitrogen analysis at the USGS WHCMSC. Sample preparation involved weighing 10-30 micrograms of ball-milled sediment into a silver capsule, sediment was moistened and placed in a fuming hydrochloric acid desiccator overnight. The sample was subsequently dried at 60 degrees Celsius and then encapsulated for carbon and nitrogen analysis via a Perkin Elmer 2400 Series II CHNS/O analyzer. Standards, blanks and reference sediment with a known carbon and nitrogen content were run to verify results (see attribute accuracy report for further details). Analysis of fumed samples yields organic carbon and nitrogen. These analyses occurred concurrently with analyses in the previous process step; after radioisotope analysis was completed on a core, we would begin the total carbon and nitrogen analysis (as other cores were still in the process of being analyzed for radioisotopes). Person who carried out this activity:
    Adrian C Mann
    Northeast Region: WOODS HOLE COASTAL AND MARINE SCIENCE CENTER
    Physical Scientist, Lab and Safety Manager
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2316 (voice)
    amann@usgs.gov
    Date: 2016 (process 4 of 5)
    Samples were run for loss on ignition (%LOI) to determine the operationally-defined organic matter content. %LOI is commonly used as a proxy for organic carbon content, since %LOI is an easy and inexpensive approach. Thus, these samples will be used to determine a relationship between %LOI and %C. A fraction of sediment (1 to 10 grams) was weighed, then burned in a muffle furnace for 4 hours at 450 degrees Celsius and reweighed to determine percent loss on ignition (%LOI). LOI% = (pre weight-post weight)/(pre weight)×100%
    Date: 2021 (process 5 of 5)
    Raw data was entered into an EXCEL spreadsheet where all calculations were completed. The Excel spreadsheet was exported as a CSV file from Excel for Mac version 15.33. The CSV file was processed in Matlab to round calculated values to appropriate place values and again exported as a comma separated text file. Note that all calculations were performed prior to rounding and truncating values reported in this data release. Person who carried out this activity:
    Meagan J Eagle
    Northeast Region: WOODS HOLE COASTAL and MARINE SCIENCE CENTER
    Research Physical Scientist
    384 Woods Hole Road
    Woods Hole, MA
    US

    508-548-8700 x2280 (voice)
    meagle@usgs.gov
  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?
    Radioisotope detection limits are specific to an individual sample and are a function of: 1) the detector efficiency at the energy of the peak being measured; 2) the branching ratio (number of decay events observed in each peak), 3) the background activity within the sample. Detector efficiency was determined from EPA standard pitchblende ore in the same geometry as the samples. Activities of 7Be, 137Cs, and 210Pb were decay corrected to time of collection. Suppression of low energy peaks by self-absorption was corrected for according to Cutshall and others, 1983. Peak detection, with respect to background activity, is calculated for each radioisotope in the APTEC software during sample analysis. Generally, measured radioisotope activity greater than or equal to 0.26 (210Pb), 0.15 (226Ra), 0.71 (7Be), and 0.007 (137Cs) dpm/g were accepted as above detection limit for this dataset. Any analysis value below detection is given the numerical value of 0. Any attribute that was not measured for a specific sample is left as a blank cell.
    Samples were analyzed for Total Carbon (TC) and Nitrogen (TN) on a Perkin-Elmer Series II CHNS/O Elemental Analyzer at USGS Woods Hole Coastal and Marine Science Center (WHCMSC). A series of calibration blanks and reference standards were analyzed daily. A standard reference estuarine marine sediment, MESS-2, was analyzed throughout each set of sample runs and was determined to have an average wt%C of 2.10±0.04 and wt%N of 0.17±0.03, compared to published values of 2.14±0.03 and 0.16 respectively. For determination of Organic Carbon (OC) and Nitrogen (ON), samples, along with blanks and standards were placed in a fuming hydrochloric acid desiccator overnight. Fumed Mess-2 was determined to have an average of 1.40±0.08 wt%OC and 0.15±0.01 wt%ON. Triplicate samples had an average relative standard deviation of 6.3% OC and 5.0% ON. The detection limit was determined as wt%OC of 0.10 and wt%ON of 0.01. Any analysis value below detection is given the numerical value of 0. Any attribute that wasn't measured for a specific sample is left as a blank cell.
    Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210 Pb in sediment samples—Self-absorption corrections: Nuclear Instruments and Methods in Physics Research, v. 206, issues 1–2, p. 309–312, https://doi.org/10.1016/0167-5087(83)91273-5.
  2. How accurate are the geographic locations?
    Latitude and longitude were measured, by study collaborators, with a differential global positioning system (DGPS). This system uses information from satellites combined with a ground station correction to ideally provide sub-centimeter location accuracy in both the horizontal (latitude, longitude) and vertical (elevation) planes. Briefly, at each site a 3-meter antenna pole was staked at the core location for 20-30 minutes during core collection; positional accuracy was calculated as the standard deviation of repeated measurements at each site and summarized for each site below.
    Upper Tampa Bay, Salt barren: 0.003 meters Upper Tampa Bay, Juncus marsh: 0.060 meters Rocky Creek: 0.003 meters E.G. Simmons: 1.827 meters Fort de Soto: 1.366 meters Holly House: 0.079 meters Weedon Island: 0.446 meters
  3. How accurate are the heights or depths?
    Site elevation was evaluated with a differential global positioning system (DGPS). This system uses information from satellites combined with a ground station correction to ideally provide sub-centimeter location accuracy in both the horizontal (latitude, longitude) and vertical (elevation) planes. Briefly, at each site a 3-meter antenna pole was staked at the core location for 20-30 minutes during core collection; vertical positional accuracy was calculated as the standard deviation of repeated measurements at each site and summarized for each site below. We found that the antenna height was not sufficient to achieve accurate results within the mangrove canopy, therefore elevation data for those sites is not well resolved. One marsh and salt barren sites had much better accuracy for elevation.
    Upper Tampa Bay, Salt barren: 0.004 meters standard deviation Upper Tampa Bay, Juncus marsh: 0.071 meters Rocky Creek: 0.006 meters E.G. Simmons: 2.053 meters Fort de Soto: 2.512 meters Holly House: 0.097 meters Weedon Island: 0.597 meters
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. All sample measurements are reported.
  5. How consistent are the relationships among the observations, including topology?
    Dataset was queried for maximum and minimum values to be sure sample analyses were within expected ranges for the environmental conditions. Data were plotted to look for any obvious outliers that may have been indicative of analytical error. Samples with questionable results was re-analyzed according to standard operating procedures. Detection limits are defined attribute accuracy section of the metadata. Any analysis value below detection is given the numerical value of 0. Any attribute that wasn't measured for a specific sample is listed as an empty or blank cell. Each sample was treated in the same manner for each analysis.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints none
Use_Constraints none
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    US

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The data release includes 1 comma-delimited text file. The user must have software capable of opening the text file and reading the data formats.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
Jennifer A. O'Keefe Suttles
Northeast Region: WOODS HOLE COASTAL AND MARINE SCIENCE CENTER
Chemist
384 Woods Hole Road
Woods Hole, MA
United States

508-548-8700 x2385 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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