Collection, Analysis, and Age-Dating of Sediment Cores from Salt Marshes, Rhode Island, 2016

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Frequently anticipated questions:

What does this data set describe?

Title:
Collection, Analysis, and Age-Dating of Sediment Cores from Salt Marshes, Rhode Island, 2016
Abstract:
The accretion history of fringing salt marshes in Narragansett Bay, Rhode Island, was reconstructed from sediment cores. Age models, based on excess lead-210 and cesium-137 radionuclide analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. The Constant Rate of Supply (CRS) age model was used to date six cores collected from three salt marshes. Both vertical accretion rates and carbon burial increased from 1900 to 2016, the year the data were collected. Cores were up to 90 cm in length with dry bulk density ranging from 0.07 to 3.08 grams per cubic centimeter and carbon content 0.71 % to 33.58 %.
Supplemental_Information:
For more information, see the following field activity: https://cmgds.marine.usgs.gov/fan_info.php?fan=2016-016-FA
  1. How might this data set be cited?
    Jennifer A. O'Keefe Suttles, Eagle, Meagan J., Mann, Adrian G., Moseman-Valtierra, Serena, Pratt, Sara E., and Kroeger, Kevin D., 20210630, Collection, Analysis, and Age-Dating of Sediment Cores from Salt Marshes, Rhode Island, 2016: data release DOI:10.5066/P94HIDVU, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: O’Keefe Suttles, J.A., Eagle, M.J., Mann, A.G., Moseman-Valtierra, S., Pratt, S.E., Kroeger, K.D., 2021, Collection, analysis, and age-dating of sediment cores from salt marshes, Rhode Island, 2016: U.S. Geological Survey data release, https://doi.org/10.5066/P94HIDVU.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -71.512756347656
    East_Bounding_Coordinate: -71.163940429688
    North_Bounding_Coordinate: 41.861379155874
    South_Bounding_Coordinate: 41.576415977893
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/60bfb7c2d34e86b938916d1e/?name=RI_salt_marsh.jpeg (JPEG)
    Browse graphic showing salt marsh vegetation at one of the Rhode Island coring sites.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 09-Sep-2016
    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. It contains the following vector data types (SDTS terminology):
      • Point (353)
    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.
  7. How does the data set describe geographic features?
    Data_RI_Marsh_Core.csv
    Comma separated text file with salt marsh core data collected from sites in Narragansett Bay. The CSV 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: radionuclide data, soil carbon and nitrogen content. The dataset includes 353 records. (Source: Producer defined)
    Site
    A text identifier for the general location of the study site. (Source: Producer-defined)
    ValueDefinition
    Narragansett BayA data point from a sediment core collected from a salt marsh in Narragansett Bay.
    Status
    A text identifier indicating the vegetation type that now dominates the core collection site. (Source: Producer-defined)
    ValueDefinition
    Salt marshData point collected from a study site that is dominated by salt marsh plant species (e.g. Spartina alterniflora or Spartina patens).
    ID
    Core ID: Each core is assigned an alphabetical identification code to indicate from which marsh it was collected (defined below) and a secondary qualifier of A or B, indicating the order of core collection over time. (Source: Producer-defined)
    ValueDefinition
    MCAMary's Creek site, core A. Salt marsh located in Warwick, Rhode Island.
    MCBMary's Creek site, core B. Salt marsh located in Warwick, Rhode Island.
    PIAPrudence Island site, core A. Salt marsh located on Prudence Island, Rhode Island.
    PIBPrudence Island site, core B. Salt marsh located on Prudence Island, Rhode Island.
    MDAMary Donovan site, core A. Salt marsh located in Little Compton, Rhode Island.
    MDBMary Donovan site, core B. Salt marsh located in Little Compton, Rhode Island.
    Date
    Collection 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:9/9/2016
    Maximum:9/12/2016
    Units:mm/dd/yy
    Lat
    Latitude: Latitude decimal degrees north, NAD83. (Source: Producer-defined)
    Range of values
    Minimum:41.54387
    Maximum:41.69060
    Units:decimal degrees
    Lon
    Longitude: Longitude decimal degrees west, NAD83. (Source: Producer defined)
    Range of values
    Minimum:-71.45162
    Maximum:-71.20399
    Units:decimal degrees
    Depth_mid
    Depth: 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:89.0
    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:0.0700
    Maximum:3.0789
    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 kiloelectron volts (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 radionuclides. (Source: Producer-defined)
    Range of values
    Minimum:0.0208
    Maximum:1.0481
    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. If the radionuclide is below detection, then the associated error is also reported with a value 0.00. (Source: Producer-defined)
    Range of values
    Minimum:0.0106
    Maximum:0.3855
    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 kiloelectron volts (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 radionuclides. (Source: Producer-defined)
    Range of values
    Minimum:0.0219
    Maximum:1.5942
    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. If the radionuclide is below detection, then the associated error is also reported with a value 0.00. (Source: Producer-defined)
    Range of values
    Minimum:0.0374
    Maximum:0.3314
    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), decay-corrected to date of core collection. Calculated as the difference between total 210-Lead and total radium-226 activities. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:-0.6223
    Maximum:23.9884
    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:-0.0220
    Maximum:16.6860
    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), decay-corrected to date of core collection. Measured at 662 kiloelectron volts (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 radionuclides. (Source: Producer-defined)
    Range of values
    Minimum:0.0140
    Maximum:1.2017
    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. If the radionuclide is below detection, then the associated error is also reported with a value 0.00. (Source: Producer-defined)
    Range of values
    Minimum:0.0078
    Maximum:0.3200
    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), decay-corrected to date of core collection. Measured at 477 kiloelectron volts (KeV) on a planar 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 radionuclides. (Source: Producer-defined)
    Range of values
    Minimum:0.0366
    Maximum:13.7111
    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), decay-corrected to date of core collection. Blank/empty cells indicate the measurement was not done. If the radioisope is below detection, then the associated error is also reported with a value 0.00. (Source: Producer-defined)
    Range of values
    Minimum:0.1575
    Maximum:1.6769
    Units:decays per minute per gram
    wtC
    Total amount of carbon by weight percent in soil. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:0.71
    Maximum:33.58
    Units:unitless
    wtN
    Total amount of nitrogen by weight percent in soil. Blank/empty cells indicate the measurement was not done. (Source: Producer defined)
    Range of values
    Minimum:0.01
    Maximum:3.48
    Units:unitless
    Age
    A numeric identifier for the age in years from the collection date of the core interval based on the Constant Rate of Supply excess lead-210 age model. Blank/empty cells indicate the measurement was not done. (Source: Producer-defined)
    Range of values
    Minimum:0.9
    Maximum:115.2
    Units:years
    Age_e
    A numeric identifier for the age model uncertainty in years of the core interval based on the Constant Rate of Supply excess 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:0.9
    Maximum:32.0
    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:1.0
    Maximum:39.6
    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:231
    Maximum:49503
    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:38
    Maximum:415
    Units:grams of carbon per square meter per year
    Year
    Year: The year corresponding to the soil horizon based on the Constant Rate of Supply excess lead-210 age model. Calculated as collection date minus age of sediment at each depth interval. (Source: Producer-defined)
    Range of values
    Minimum:1901.6
    Maximum:2016.0
    Units:Calendar Year

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Jennifer A. O'Keefe Suttles
    • Meagan J. Eagle
    • Adrian G. Mann
    • Serena Moseman-Valtierra
    • Sara E. Pratt
    • Kevin D. Kroeger
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    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

Why was the data set created?

Sediment cores were collected and dated, and their carbon content was measured to determine vertical accretion and carbon burial rates.

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: 2016 (process 1 of 4)
    Six sediment cores were collected in coastal salt marshes between 9/9/2016 and 9/12/16. A piston coring system was used, where the core liner (diameter 11 cm, 1-2 m in length) was fitted with a gasketed piston that was placed on the sediment surface. The clear, sharpened core liner was pushed down into the marsh subsurface, while the piston was maintained at the marsh surface via tension on the piston. We visually observed the sediment surface to ensure that the soil column did not compact during collection. Once the core reached the maximum depth (limited by the core tube length or an impenetrable sediment layer), the core liner and piston were removed from the marsh with a pulley system. The process date reflects the last occurrence of the work.
    Date: 2017 (process 2 of 4)
    At the end of each core collection date, the sediment cores were immediately returned to the Woods Hole Coastal and Marine Science Center. They were placed in a refrigerator for 1 to 3 days, then split vertically, sectioned at 1 or 2 cm intervals, frozen, and then freeze dried for 7 days, until sediment weights did not change further. 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 kiloelectron volts (KeV) energies, respectively (Canberra Inc., USA). Detector efficiency was determined from EPA standard pitchblende ore in the same geometry as the samples. Excess 210Pb was calculated as the decay-corrected difference between total 210Pb and supported 210Pb (considered to be equal to 226Ra). Activities of 7Be, 137Cs, and 210Pb were decay-corrected to time of collection, using their respective half-lives. Suppression of low energy peaks by self-absorption was corrected for according to Cutshall and others, 1983. Gamma spectroscopy detection limits were determined in APTEC software for each sample; refer to the attribute accuracy section of this metadata for further details. Values reported are above this limit, while values below are reported as 0. Core sections not analyzed are reported as blank cells. Sediment ages and accretion rates were calculated with the Constant Rate of Supply (CRS) excess 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 excess 210Pb. The common form of the CRS model, as derived by Appleby and Oldfield (1978), solves for age based on the distribution of excess 210Pb in the sediment record. Prior to application of the age model, excess 210Pb profiles were evaluated to ensure they were sufficiently resolved to apply the CRS model without bias towards to ages that are too old or accretion rates that are too low at depth (Binford, 1990). All gamma analyses were ongoing from 2016 and completed in 2017.
    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.
    Date: 2019 (process 3 of 4)
    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 Woods Hole Coastal and Marine Science Center. Sample preparation involved weighing 10-30 micrograms of ball-milled sediment into a tin capsule; encapsulated samples were analyzed for carbon and nitrogen on 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). These analyses occurred concurrently with analyses in the previous process step; after radionuclide 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 radionuclide). 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: 2020 (process 4 of 4)
    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 (*.csv). Note that all calculations were performed prior to rounding and truncating values reported in this data release.
  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?
    Radionuclide detection limits are specific to an individual sample and are a function of: 1) the detector efficiency at the energy of level of the peak being measured; 2) the branching ratio (expected fraction of decay events observed at each energy level), 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 excess 210Pb (i.e. unsupported) 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 radionuclide in the APTEC peak integration spectroscopy software during sample analysis. Generally, measured radionuclide activity greater than or equal to 0.02 (210Pb), 0.02 (226Ra), 0.03 (7Be), and 0.01 (137Cs) dpm/g were accepted as above detection limit for this dataset.
    Samples were analyzed for Total Carbon and Nitrogen on a Perkin-Elmer Series II CHNS/O Elemental Analyzer at USGS Woods Hole Coastal and Marine Science Center. A series of calibration blanks and reference standards were analyzed daily. Standard reference materials (Algae (Bladderwrack), High Organic Sediment Standard and BCSS-1) were analyzed throughout each set of sample runs. Algae was determined to have an average weight percent carbon (wt%C) of 36.45 and weight percent nitrogen (wt%N) of 1.33, compared to published values of 33.67 ± 0.29 and 1.25 ± 0.0.02, respectively. The High Organic Sediment Standard was determined to have an average wt%C of 7.32 and wt%N of 0.53, compared to published values of 7.45 ± 0.14 and 0.52 ± 0.02, respectively. BCSS-1 was determined to have an average wt%C of 2.26 and wt%N of 0.17 compared to published values of 2.19 ± 0.09 and 0.07 ± 0.003, respectively. Triplicate samples had an average relative standard deviation of 2.9 %C and 3.3 %N. The detection limit was determined as wt%C of 0.18 and wt%N of 0.01. 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.
  2. How accurate are the geographic locations?
    Latitude and Longitude was measured with a handheld Garmin GPSMAP 76Cx unit in the field at time of collection. The GPS unit indicated accuracy was within 3 meters. No formal positional accuracy tests were conducted.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. 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 were re-analyzed. Detection limits are defined in the attribute accuracy section of the metadata. Any analysis value below detection is given the numerical value of 0. Any attribute that was not 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)
    ScienceBase
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains one CSV file containing the data (Data_RI_Marsh_Core.csv), the browse graphic, and the FGDC CSDGM metadata in XML format.
  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 file and reading the data formats.

Who wrote the metadata?

Dates:
Last modified: 30-Jun-2021
Metadata author:
Jennifer A O'Keefe Suttles
Northeast Region: WOODS HOLE COASTAL AND MARINE SCIENCE CENTER
Chemist
384 Woods Hole Road
Woods Hole, MA
US

508-548-8700 x2385 (voice)
jokeefesuttles@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P94HIDVU/meta_RhodeIsland_Cores.faq.html>
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