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

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?
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  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., 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:

   • https://doi.org/10.5066/P9QB17H2
   • https://www.sciencebase.gov/catalog/item/60bfb8a4d34e86b938916d6f

   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)

   Value	Definition
   E.G. Simmons	A data point from a sediment core collected within a wetland at E.G. Simmons Park (Ruskin, Florida).
   Fort de Soto	A data point from a sediment core collected within a wetland at Fort de Soto Park, (St. Petersburg, Florida).
   Holly House	A 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 Creek	A data point from a sediment core collected within a wetland along Rocky Creek (Tampa, Florida).
   Upper Tampa Bay	A data point from a sediment core collected within a wetland in the Upper Tampa Bay region (Tampa, Florida).
   Weedon Island	A 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)

   Value	Definition
   Mangrove	Data point collected from a location dominated by mature mangrove vegetation.
   Juncus Marsh	Data point collected from a location that is now dominated by Juncus salt marsh vegetation.
   Salt Barren	Data point collected from a location without much vegetation cover although it may be adjacent to a vegetated area.
   Young Mangrove	Data 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)

   Value	Definition
   EGSA	E.G. Simmons, core A
   EGSB	E.G. Simmons, core B
   FDS	Fort de Soto
   HHMA	Holly House, Mangrove, core A
   HHMB	Holly House, Mangrove, core B
   RCRA	Rocky Creek, core A
   RCRB	Rocky Creek, core B
   UTR	Upper Tampa Bay
   UTSB	Upper Tampa Bay, Salt Barren
   WI	Weedon 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?

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?

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?
   • Availability in digital form:

     Data format:	CSV (version Microsoft Excel Office 365) The data release includes 1 comma separated file, a browse graphic, and the FGDC CSDGM metadata. Size: 1
     Network links:	https://www.sciencebase.gov/catalog/file/get/60bfb8a4d34e86b938916d6f https://www.sciencebase.gov/catalog/item/60bfb8a4d34e86b938916d6f https://doi.org/10.5066/P9QB17H2

   • 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)