Collection, analysis, and age-dating of sediment cores from natural and restored salt marshes on Cape Cod, Massachusetts, 2015-16

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• 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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   O'Keefe Suttles, Jennifer A., Eagle, Meagan J., Mann, Adrian G., Spivak, Amanda, Sanks, Kelly, Roberts, Daniel, and Kroeger, Kevin D., 20210630, Collection, analysis, and age-dating of sediment cores from natural and restored salt marshes on Cape Cod, Massachusetts, 2015-16: data release DOI: 10.5066/P9R154DY, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9R154DY
   • https://www.sciencebase.gov/catalog/item/60bfb987d34e86b938916dc9

   Other_Citation_Details:

   Suggested citation: O'Keefe Suttles, J.A., Eagle, M.J., Mann, A.G., Spivak, A., Sanks, K., Roberts, D., and Kroeger, K.D., 2021, Collection, analysis, and age-dating of sediment cores from natural and restored salt marshes on Cape Cod, Massachusetts, 2015 -2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9R154DY

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -70.669555664063
   East_Bounding_Coordinate: -69.908752441406
   North_Bounding_Coordinate: 41.941105783816
   South_Bounding_Coordinate: 41.510634060621
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/60bfb987d34e86b938916dc9/?name=CapeCod_Restored_Salt_marsh.jpg (JPEG)

   Photograph of a tidal salt marsh creek at low tide with a restored tidal restriction/bridge in the background (Bass Creek, Yarmouth, MA).

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

   Calendar_Date: 03-Jun-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 (*.csv) file
   

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 (1075)
   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:

      Depth_System_Definition:

      Depth_Datum_Name: North American Vertical Datum of 1988 (NAVD88)
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
      

7. How does the data set describe geographic features?

   Data_RestoredMarshes_Cores.csv

   Comma separated text file with soil core data collected from natural and restored salt marsh sites Cape Cod, MA. 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 1075 records (Source: Producer defined)

   Site

   A text identifier for the general location of the study site. (Source: Producer defined)

   Value	Definition
   Quivett	Quivett Creek, Dennis, MA
   Bass	Bass Creek, Yarmouth, MA
   Stony	Stony Brook, Brewster, MA
   Boat	Boat Meadow, Eastham and Orleans, MA
   Scusset	Scusset marsh (restored) and Mill Creek marsh (natural), Sagamore and Sandwich, MA

   Status

   A text identifier indicating whether the core was collected in a natural marsh or a formerly restricted (now restored) marsh. (Source: Producer defined)

   Value	Definition
   Natural	Marsh with no history of hydrologic restriction.
   Restored	Marsh with history of hydrologic restriciton, now with tidal exchange restored.

   ID

   Abbreviated alphabetical identification code of each core to indicate: 1) the marsh site from which it was collected (using a two letter abbreviation); 2) the status of the marsh (N for natural, R for Restored); and 3) a qualifier of A, B or C to indicate the order of core collection over time. (Source: Producer defined)

   Value	Definition
   QCNA	Quivett Creek, natural core A
   QCNB	Quivett Creek, natural core B
   QCRA	Quivett Creek, restored core A
   BCNA	Bass Creek, natural core A
   BCNB	Bass Creek, natural core B
   BCRA	Bass Creek, restored core A
   BCRB	Bass Creek, restored core B
   SBNA	Stony Brook, natural core A
   SBNB	Stony Brook, natural core B
   SBRA	Stony Brook, restored core A
   SBRB	Stony Brook, restored core B
   BMNA	Boat Meadow, natural core A
   BMNB	Boat Meadow, natural core B
   BMRA	Boat Meadow, restored core A
   BMRB	Boat Meadow, restored core B
   SMRB	Scussett Marsh, restored core B
   SMRC	Scussett Marsh, restored core C
   MCNA	Mill Creek, natural core A
   MCNB	Mill Creek, natural core B

   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:	06/03/2015
   Maximum:	07/19/2016
   Units:	date: month/day/year

   Lat

   Latitude decimal degrees north, NAD83. (Source: Producer defined)

   Range of values
   Minimum:	41.71575
   Maximum:	41.80291
   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:	-70.51978
   Maximum:	-69.98568
   Units:	decimal degrees

   Depth

   A numeric identifier of the interval mid-point depth below the sediment interface in centimeters. Note that depth = 0 cm is given as a reference point in order to include the land surface elevation within the dataset. Sediment core analyses are not reported for this sample depth because it is not a sampled horizon within a collected core. The minimum interval mid-point for each core is 0.5 cm. (Source: Producer defined)

   Range of values
   Minimum:	0.0
   Maximum:	167.0
   Units:	centimeters

   Elevation

   A numeric identifier of interval mid-point elevation relative to NAVD88 datum in centimeters. Calculated by subtracting the mid-interval sample depth from the NAVD88 elevation of the core location reported as depth = 0 cm within the dataset for each core. (Source: Producer defined)

   Range of values
   Minimum:	-118.6
   Maximum:	151.0
   Units:	centimeter

   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:	0.0358
   Maximum:	2.6248
   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. (Source: Producer defined)

   Range of values
   Minimum:	0.2709
   Maximum:	34.9084
   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. (Source: Producer defined)

   Range of values
   Minimum:	0.0345
   Maximum:	0.9975
   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. (Source: Producer defined)

   Range of values
   Minimum:	0.0360
   Maximum:	3.0504
   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:	0.0098
   Maximum:	0.4011
   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 lead-210 and total radium-226 activities. Blank/empty cells indicate the measurement was not done. (Source: Producer defined)

   Range of values
   Minimum:	-0.3410
   Maximum:	34.2095
   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), decay-corrected to date of core collection. Blank/empty cells indicate the measurement was not done. (Source: Producer defined)

   Range of values
   Minimum:	0.0385
   Maximum:	1.0243
   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. (Source: Producer defined)

   Range of values
   Minimum:	0.0037
   Maximum:	12.3840
   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), decay-corrected to date of core collection. 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:	0.0010
   Maximum:	0.9418
   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. 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:	0.4667
   Maximum:	38.0003
   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. The value 0.00 is given to analyzed samples found to be below detection. (Source: Producer defined)

   Range of values
   Minimum:	0.0773
   Maximum:	7.3151
   Units:	decays per minute per gram

   wtC

   Either total carbon or total organic carbon by weight percent in soil. Sediments in this sample set that were analyzed for both carbon content and isotopic carbon signature were not fumed prior to analysis and reported wtC is total carbon. Sediment sections without a reported isotopic signature were run in a separate lab and were fumed 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:	0.12
   Maximum:	48.91
   Units:	unitless

   wtN

   Either total nitrogen or total organic nitrogen by weight percent in soil. Sediments in this sample set that were analyzed for both nitrogen content and isotopic nitrogen signature were not fumed prior to analysis and reported wtN is total nitrogen. Sediment sections without a reported isotopic signature were run in a separate lab and were placed in an 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:	1.94
   Units:	unitless

   13C

   The carbon isotopic signature of the soil sample relative to Pee Dee Belemnite (PDB) standard. Blank/empty cells indicate the measurement was not done. (Source: Producer defined)

   Range of values
   Minimum:	-29.10
   Maximum:	-11.84
   Units:	parts per thousand OR per mil

   15N

   The nitrogen isotopic signature of the soil sample relative to air. Blank/empty cells indicate the measurement was not done. (Source: Producer defined)

   Range of values
   Minimum:	-1.24
   Maximum:	5.79
   Units:	parts per thousand OR per mil

   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:	0.4
   Maximum:	136.2
   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:	0.6
   Maximum:	51.8
   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:	0.8
   Maximum:	26.2
   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:	163
   Maximum:	7858
   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:	15
   Maximum:	603
   Units:	grams of carbon per square meter per 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:	1879.4
   Maximum:	2016.6
   Units:	calendar year

   Year_restored

   Calendar year corresponding to when restoration occurred. (Source: Producer defined)

   Range of values
   Minimum:	2001
   Maximum:	2010
   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)
   • O'Keefe Suttles, Jennifer A.
   • Eagle, Meagan J.
   • Mann, Adrian G.
   • Spivak, Amanda
   • Sanks, Kelly
   • Roberts, Daniel
   • Kroeger, Kevin D.
2. Who also contributed to the data set?
   Barry Irwin (USGS Geophysicist), Sandra Brosnahan (USGS Physical Scientist), and Jonathan Borden (USGS Electronics Technician) helped with RTK GPS data collection at these study sites.
3. To whom should users address questions about the data?
   Meagan J Eagle

   Northeast Region: WOODS HOLE COASTAL and 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?

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)

   19 sediment cores were collected in coastal salt marshes in 2015 and 2016. A piston coring system was used, where the PVC 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 desired depth, the core liner and piston were removed from the marsh with a pulley system. The process date reflects the last occurrence of the work. 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

   Date: 2017 (process 2 of 4)

   At the end of each core collection date, the sediment cores were immediately returned to the USGS 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 excess 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 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 2017.
   Appleby, P.G., and Oldfield, Frank, 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 and MARINE SCIENCE CENTER

   Research Physical Scientist

   384 Woods Hole Road

   Woods Hole, MA
   

   US

   508-548-8700 x2280 (voice)

   meagle@usgs.gov

   Date: 2019 (process 3 of 4)

   A sub-sample of freeze dried sediment (0.5 g) was ball-milled to a fine powder and packaged for analysis Total Carbon and Nitrogen. Samples were analyzed for carbon and nitrogen content in one of two laboratories. 1) Samples reported with both isotopic signature and weight percent of carbon and nitrogen were analyzed by the University of California - Davis (UC Davis), Stable Isotope Facility (SIF) with an Elementar Vario EL Cube or Micro Cube elemental analyzer interfaced to a PDZ Europa 20-20 isotope ratio mass spectrometer. During analysis, samples were interspersed with several replicates of at least four different laboratory reference material; these reference materials have a long term standard deviation is 0.2 per mil for 13C and 0.3 per mil for 15N. 2) Samples reported with only weight percent of carbon and nitrogen (no isotopic signature reported) were analyzed by the USGS Woods Hole Coastal and Marine Science Center. 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; analysis of non-fumed samples yields total carbon and nitrogen. These analyses occurred concurrently with analyses in the previous process step; after radionuclide analysis was completed on a core, we would begin the carbon and nitrogen analysis (as other cores were still in the process of being analyzed for radionuclide)

   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. Person who carried out this activity:
   

   Meagan J. Eagle

   U.S. Geological Survey

   Research Physical Scientist

   384 Woods Hole Rd.

   Woods Hole, MA
   

   United States

   508-548-8700 x 2280 (voice)

   meagle@usgs.gov

3. What similar or related data should the user be aware of?
   O’Keefe Suttles, Jennifer A., Brosnahan, Sandra M., Gonneea, Meagan E., and Kroeger, Kevin D., 2019, Continuous monitoring data from natural and restored salt marshes on Cape Cod, Massachusetts, 2016-17: data release DOI:10.5066/P9YLXOY8, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.5066/P9YLXOY8
   • https://www.sciencebase.gov/catalog/item/5da76672e4b09fd3b0c9c134

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 level of the peak being measured; 2) the branching ratio (expected fraction of decay events at the 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 0.270 (210Pb), 0.036 (226Ra), 0.466 (7Be), and 0.003 (137Cs) dpm/g were accepted as above detection limit for this dataset.
   Samples were analyzed for carbon and nitrogen content in one of two laboratories. 1) Samples reported with both isotopic signature and weight percent of carbon and nitrogen were analyzed by the University of California - Davis (UC Davis), Stable Isotope Facility (SIF) with an Elementar Vario EL Cube or Micro Cube elemental analyzer interfaced to a PDZ Europa 20-20 isotope ratio mass spectrometer. During analysis, samples were interspersed with several replicates of at least four different laboratory reference material; these reference materials have a long term standard deviation is 0.2 per mil for 13C and 0.3 per mil for 15N. 2) Samples reported with only weight percent of carbon and nitrogen (no istopic signature reported) 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. 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 was not 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 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?
   Land surface elevations were measured by Trimble Real-Time Kinematic (RTK) GPS across the collection area after core collection. Surveyors returned to the core collection sites, navigated to the core collection locations, and surveyed several points. Average vertical accuracy of this method is +/- 5 centimeters. No formal positional accuracy tests were conducted.
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. All sample measurements are reported. Note that no samples were analyzed (and no data is reported) for two cores that were collected (QCRB or SMA) because these cores were found to be unusable once brought back for sectioning in the laboratory. Scusset Marsh (SM) is the only site from which a "C" core was collected. Users are advised to read the rest of the metadata record carefully for additional details.
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. For samples that had detectable total 210Pb but 226Ra was below detection, an estimate of 226Ra, based on the measured values throughout the core, was used to create the age-model. Those estimated 226Ra values and their uncertainties are: 0.5000, 0.0000 for core IDs QCNA and QCNB; 0.5000, 0.1000 for core IDs QCRA, BMRA; 0.6000, 0.1000 for core IDs SBNA, SBNB, SBRB, BMRB; 0.4000, 0.1000 for core ID SBRA; 0.7513, 0.0757 for core SMB. 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?

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
   

   US

   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_RestoredMarsh_Cores.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?
   • Availability in digital form:

     Data format:	The data release includes 1 comma separated file, a browse graphic, and the FGDC CSDGM metadata. in format CSV (version Microsoft Excel Office 365) Size: 1
     Network links:	https://www.sciencebase.gov/catalog/file/get/60bfb987d34e86b938916dc9 https://www.sciencebase.gov/catalog/item/60bfb987d34e86b938916dc9 https://doi.org/10.5066/P9R154DY

   • Cost to order the data: None

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)