Sedimentary Data From Grand Bay, Alabama/Mississippi, 2014-2016 (ver. 1.1, April 2020)

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?
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• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Marot, Marci E., Smith, Christopher G., McCloskey, Terrence A., Locker, Stanley D., Khan, Nicole S., and Smith, Kathryn E.L., 20200428, Sedimentary Data From Grand Bay, Alabama/Mississippi, 2014-2016 (ver. 1.1, April 2020): U.S. Geological Survey Data Release doi:10.5066/P9FO8R3Y, U.S. Geological Survey, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P9FO8R3Y

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.41242
   East_Bounding_Coordinate: -88.39657
   North_Bounding_Coordinate: 30.38365
   South_Bounding_Coordinate: 30.37594
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 21-Oct-2016

   Ending_Date: 22-Oct-2016

   Currentness_Reference:

   ground condition

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: Multimedia presentation
   

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?
      
   2. What coordinate system is used to represent geographic features?
      
7. How does the data set describe geographic features?

   16CCT07_SiteInformation.xlsx

   Microsoft Excel workbook defining the field sampling dates, distance from shoreline, site locations, elevations, core lengths and core compaction for the 8 marsh push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). (Source: USGS)

   16CCT07_SiteInformation.csv

   Comma-separated values text file defining the field sampling dates, distance from shoreline, site locations, elevations, core lengths, and core compaction for the 8 marsh push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). (Source: USGS)

   16CCT07_SedimentPhysicalProperties.xlsx

   Microsoft Excel workbook listing water content, porosity, bulk density and loss-on-ignition data for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). The results for each core are provided on its own tab. (Source: USGS)

   16CCT07_SedimentPhysicalProperties.csv

   Comma-separated values text file listing water content, porosity, bulk density and loss-on-ignition data for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). (Source: USGS)

   16CCT07_GrainSize.xlsx

   Microsoft Excel workbook summarizing grain-size parameters for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). The averaged results for each sample, including the number of runs used, the standard deviation of the averaged results, and graphical class-size distributions, are provided for each core on its own tab. (Source: USGS)

   16CCT07_GrainSize.csv

   Comma-separated values text file summarizing grain-size parameters for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). The averaged results for each sample, including the number of runs used, the standard deviation of the averaged results, and graphical class-size distributions, are provided. (Source: USGS)

   16CCT07_GammaSpectroscopy.xlsx

   Microsoft Excel workbook listing gamma spectroscopy radiochemistry results for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). The results for each core are provided on its own tab. (Source: USGS)

   16CCT07_GammaSpectroscopy.csv

   Comma-separated values text file listing gamma spectroscopy radiochemistry results for the 8 push cores collected in this study (USGS FAN 2016-358-FA, project ID 16CCT07). (Source: USGS)

   Site ID

   Site identifier assigned by the USGS scientist (Source: USGS) Character string

   Date Collected

   Calendar date of field sample collection (Source: USGS)

   Range of values
   Minimum:	10/21/2016
   Maximum:	10/22/2016
   Units:	mm/dd/yyyy
   Resolution:	1

   Distance from Shoreline

   Distance of the core site from the marsh shoreline, in meters (Source: USGS)

   Range of values
   Minimum:	5
   Maximum:	50
   Units:	Meter
   Resolution:	1

   Latitude (NAD83)

   Latitude of site location relative to the North American Datum of 1983, in decimal degrees (Source: VDatum)

   Range of values
   Minimum:	30.37600
   Maximum:	30.38365
   Units:	Decimal degree
   Resolution:	0.00001

   Longitude (NAD83)

   Longitude of site location relative to the North American Datum of 1983, in decimal degrees (Source: VDatum)

   Range of values
   Minimum:	-88.41242
   Maximum:	-88.39657
   Units:	Decimal degree
   Resolution:	0.00001

   Orthometric Height (m, NAVD88 Geoid 12A)

   Orthometric height of site location relative to the North American Vertical Datum of 1988 using Geoid 12A, in meters (Source: VDatum)

   Range of values
   Minimum:	0.158
   Maximum:	0.305
   Units:	Meter

   Push Core Recovered Length (cm)

   Field measurement of the recovered push core length, in centimeters (Source: USGS)

   Range of values
   Minimum:	42
   Maximum:	54
   Units:	Centimeter
   Resolution:	0.5

   Push Core Compaction During Coring (cm)

   Field measurement of sediment compaction in the push cores during coring, in centimeters (Source: USGS)

   Range of values
   Minimum:	3
   Maximum:	9
   Units:	Centimeter
   Resolution:	0.5

   Core ID

   Core identifier assigned by the USGS scientist (Source: USGS) Character string

   Depth (cm)

   Depth interval measured from below the core surface, in centimeters (Source: USGS)

   Range of values
   Minimum:	Top (unconsolidated sediment)
   Maximum:	51-52
   Units:	Centimeter
   Resolution:	0.1

   Water Content (g-water/g-wet)

   The ratio of the mass of water to the mass of wet sediment (Source: USGS)

   Range of values
   Minimum:	0.26
   Maximum:	0.73
   Units:	Gram of water per gram of wet sediment
   Resolution:	0.01

   Porosity (cm^3-voids/cm^3-wet)

   Porosity of the sediment interval (Source: USGS)

   Range of values
   Minimum:	0.47
   Maximum:	0.87
   Units:	Cubic centimeter of void space per cubic centimeter of wet sediment
   Resolution:	0.01

   Dry Bulk Density (g/cm^3)

   Dry bulk density of the sediment interval (Source: USGS)

   Range of values
   Minimum:	0.28
   Maximum:	1.27
   Units:	Gram per cubic centimeter
   Resolution:	0.01

   Loss On Ignition (g-OM/g-dry)

   The ratio of the mass of organic matter combusted at 550 Celsius to the pre-combusted mass of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.022
   Maximum:	0.280
   Units:	Gram of organic matter per gram of dry sediment
   Resolution:	0.001

   Cs-137 (dpm/g)

   Cesium-137 specific activity measured in disintegrations per minute per gram of dry sediment decay-corrected to the date of field collection (Source: USGS)

   Range of values
   Minimum:	Not Detected
   Maximum:	1.75
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Cs-137 Error (+/- dpm/g)

   Cesium-137 specific activity counting error measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	Null
   Maximum:	0.17
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Pb-210 (dpm/g)

   Lead-210 specific activity measured in disintegrations per minute per gram of dry sediment decay-corrected to the date of field collection (Source: USGS)

   Range of values
   Minimum:	1.10
   Maximum:	7.88
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Pb-210 Error (+/- dpm/g)

   Lead-210 specific activity counting error measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.15
   Maximum:	0.58
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Ra-226 (dpm/g)

   Radium-226 specific activity measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.88
   Maximum:	1.97
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Ra-226 Error (+/- dpm/g)

   Radium-226 specific activity counting error measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.05
   Maximum:	0.20
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Th-234 (dpm/g)

   Thorium-234 specific activity measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	1.18
   Maximum:	8.24
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Th-234 Error (+/- dpm/g)

   Thorium-234 specific activity counting error measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.17
   Maximum:	0.77
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   K-40 (dpm/g)

   Potassium-40 specific activity measured in disintegrations per minute per gram of dry sediment decay-corrected to the date of field collection (Source: USGS)

   Range of values
   Minimum:	2.64
   Maximum:	26.78
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   K-40 Error (+/- dpm/g)

   Potassium-40 specific activity counting error measured in disintegrations per minute per gram of dry sediment (Source: USGS)

   Range of values
   Minimum:	0.51
   Maximum:	2.71
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Entity_and_Attribute_Overview:

   The detailed attribute descriptions for the grain size workbook are provided in the included data dictionary (16CCT07_Grain_Size_Data_Dictionary.pdf). These metadata are not complete without this file.

   Entity_and_Attribute_Detail_Citation:

   Data dictionary for grain-size data tables, in: Marot, M.E., Smith, C.G., McCloskey, T.A., Locker, S.D., Khan, N.S., and Smith, K.E.L., 2019, Sedimentary Data From Grand Bay, Alabama/Mississippi, 2014-2016: U.S. Geological Survey data release, https://doi.org/10.5066/P9FO8R3Y.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Marci E. Marot
   • Christopher G. Smith
   • Terrence A. McCloskey
   • Stanley D. Locker
   • Nicole S. Khan
   • Kathryn E.L. Smith
2. Who also contributed to the data set?

   U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center

3. To whom should users address questions about the data?
   U.S. Geological Survey

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   mmarot@usgs.gov

Why was the data set created?

Dissemination of field-collected and laboratory analytical data of sediment from push cores collected in Grand Bay marsh, Alabama/Mississippi in October 2016 (USGS FAN 2016-358-FA, project ID 16CCT07).

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 10)

   Two transects of four cores each were collected at two salt marsh sites along Grand Bay, Alabama/Mississippi. At each site, the 4 cores were collected at distances of 5, 15, 25, and 50 meters landward of the shoreline. Push cores were collected with 10.2-centimenter (cm) diameter polycarbonate barrels, driven into the sediment until refusal. Measurements were taken on the inside and outside of the barrel to determine compaction or core shortening values. Upon retrieval, the push cores were capped, labeled, and inspected for integrity. Push core recovered lengths ranged between 42 and 54 cm. Core identifiers consist of the USGS project ID (16CCT07) and a site-specific identifier (for example, GB301). An alphabetic identifier was appended to each site identifier to differentiate the collection method (M for push core). Site positioning and elevations for cores GB301M-GB304M were determined using an Ashtech differential GPS receiver. GPS locations were not recorded at the core sites GB305M-GB308M, the site location was approximated from a reference map. Elevations at core sites GB305M-GB308M were determined using a total station during site reoccupation in January 2017. Site locations, elevations, date of collection, distance from the shoreline, core lengths, and core compaction are reported in an Excel spreadsheet. Comma-separated values data files containing the tabular data in plain text are included in the download files. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_SiteInformation.zip

   Date: 2016 (process 2 of 10)

   DGPS Acquisition: DGPS base stations were erected on two NGS benchmarks located within the Grand Bay National Estuarine Research Reserve, B166 (PID DO5987) and 189A (PID DO5977). At each base station, an Ashtech Z-Xtreme DGPS receiver recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via a Thales choke-ring antenna. A similar instrument combination (Ashtech Z-Xtreme receiver and Ashtech geodetic antenna) was used for the rover GPS systems. The base receiver and the rover receiver record their positions concurrently at 1 second (s) recording intervals throughout the survey. A stop-and-go rapid-static survey technique was used, with static occupation durations of either 300 or 30 s, depending on sample site. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Marci Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Date: 2016 (process 3 of 10)

   GPS Post-Processing: The final, time weighted coordinates from 16CCT07 for the GPS base stations were imported into GrafNav, version 8.7 (Novatel Waypoint Product Group) and the data from the rover GPS were post-processed to the concurrent GPS session data from the nearest base station; baseline distances for all sample sites were less than about 8 km dependent upon site location. The GPS data were acquired in the World Geodetic System of 1984 (WGS84, (G1150)) geodetic datum, processed and exported in the North American Datum of 1983 (NAD83) geocentric datum. The exported file from GrafNav was converted using the National Oceanic and Atmospheric Association (NOAA) VDatum software conversion tool version 3.6 (http://vdatum.noaa.gov/). The sample locations were transformed from the GPS acquisition datum (WGS84) horizontal and vertical, to NAD 83, Universal Transverse Mercator (UTM) Zone 16 north (16N) horizontal reference frame and the North American Vertical Datum of 1988 (NAVD 88) orthometric elevation using the NGS geoid model of 2012A (GEOID 12A). The site information data files provided in the data release are in the Geographic Coordinate System (latitude, longitude, decimal degrees) NAD83. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Marci Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_SiteInformation.zip

   Date: 2016 (process 4 of 10)

   At the SPCMSC, the eight push cores were vertically extruded and sectioned into 1-cm intervals. The outer circumference of each interval was removed to avoid use of sediment that was in contact with the polycarbonate barrel. Each sediment interval was bagged and homogenized. The bagged intervals were refrigerated until processing. Person who carried out this activity:
   

   U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Date: 2017 (process 5 of 10)

   In the SPCMSC laboratory, a subsample of each 1-cm interval from the 8 push cores was processed for basic sediment characteristics (dry bulk density and porosity). Water content, porosity and dry bulk density were determined using water mass lost during drying. For each 1-cm interval, 10–60 milliliters (mL) of each wet subsample was packed into a graduated syringe with 0.5 mL resolution. The wet sediment was then extracted into a pre-weighed aluminum tray and the weight of the wet sediment and the volume was recorded. The wet sediment and tray were placed in a drying oven for a minimum of 48 hours at 60 degrees Celsius (°C). Water content (θ) was determined as the mass of water (mass lost when dried) relative to the initial wet sediment mass. Dry bulk density was determined by ratio of dry sediment to the known volume of sediment packed into the syringe. Porosity (φ) was calculated from the equation φ = θ / [θ+(1-θ)/ρs] where ρs is grain density assumed to be 2.5 grams per cubic centimeter (g/cm^3). Salt-mass contributions were removed based on an estimation of salinity to be 25. Water content, porosity and dry bulk density are reported in the Excel spreadsheet. A comma-separated values data file containing the tabular data in plain text is included in the download file. Person who carried out this activity:
   

   U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_SedimentPhysicalProperties.zip

   Date: 2018 (process 6 of 10)

   Organic matter content was determined with a mass loss technique, referred to as loss on ignition (LOI). The dry sediment from the previous process was homogenized with a porcelain mortar and pestle. Approximately 2-3 grams (g) of the dry sediment was placed into a pre-weighed porcelain crucible. The mass of the dried sediment was recorded. The sample was then placed inside a laboratory muffle furnace with stabilizing temperature control. The furnace was heated to 110 °C for a minimum of 6 hours to remove hygroscopic water absorbed onto the sediment particles. The furnace temperature was then lowered to 60 °C, at which point the sediments could be reweighed. The dried sediment was returned to the muffle furnace. The furnace was heated to 550 °C over 30 minutes and kept at 550 °C for 6 hours. The furnace temperature was then lowered to 60 °C and held at this temperature until the sediments could be reweighed. The latter step prevents the absorption of moisture, which can affect the measurement. The mass lost during the 6-hour baking period relative to the 110 °C-dried mass is used as a metric of organic matter content. Data are reported as a ratio of mass (g) of organic matter to mass (g) of dry sediment (post-110 °C drying). Replicate analyses of loss on ignition for a representative subset of the core intervals are reported for quality assurance in the Excel spreadsheet. A comma-separated values data file containing the tabular data in plain text is included in the download file. Person who carried out this activity:
   

   U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_SedimentPhysicalProperties.zip

   Date: 2017 (process 7 of 10)

   Down-core particle size analysis was performed on 1-cm depth interval for the eight push cores. Select intervals throughout the entire length of each core were chosen for analysis. A total of 96 samples were analyzed for particle size. Prior to particle size analysis, organic material was chemically removed from the samples using 30% hydrogen peroxide (H2O2). Wet sediment was dissolved in H2O2 overnight. The H2O2 was then evaporated by gentle heating and the sediment washed and centrifuged twice with deionized water. Grain size analyses on the sediment cores were performed using a Coulter LS 13 320 (https://www.beckmancoulter.com/) particle-size analyzer (PSA), which uses laser diffraction to measure the size distribution of sediments ranging in size from 0.4 microns to 2 millimeters (mm) (clay to very coarse-grained sand). To prevent shell fragments from damaging the Coulter instrument, particles greater than 1 mm in diameter were separated from all samples prior to analysis using a number 18 (1000 microns or 1 mm) U.S. standard sieve, which meets the American Society for Testing and Materials (ASTM) E11 standard specifications for determining particle size using woven-wire test sieves. Two subsamples from each depth interval were processed through the instrument a minimum of three runs each. The sediment slurry made from the digested sample and deionized water was sonicated with a wand sonicator for 1 minute before being introduced into the Coulter PSA to breakdown aggregated particles. The Coulter PSA measures the particle-size distribution of each sample by passing sediment suspended in solution between two narrow panes of glass in front of a laser. Light is scattered by the particles into characteristic refraction patterns measured by an array of photodetectors as intensity per unit area and recorded as relative volume for 92 size-related channels (bins). The size-classification boundaries for each bin were specified based on the ASTM E11 standard. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Date: 2017 (process 8 of 10)

   The raw grain size data were then run through the free software program GRADISTAT (Blott and Pye, 2001; http://www.kpal.co.uk/gradistat), which calculates the mean, sorting, skewness, and kurtosis of each sample geometrically in metric units and logarithmically in phi units. GRADISTAT also calculates the fraction of sediment from each sample by size category (for example, clay, coarse silt, fine sand). A macro function in Microsoft Excel, developed by the USGS SPCMSC, was applied to the data to calculate average and standard deviation for each sample set (8 runs per sample), and highlighted runs that varied from the set average by more than ±1.5 standard deviations. Excessive deviations from the mean are likely the result of equipment error or extraneous organic material in the sample and are not considered representative of the sample. The highlighted runs were removed from the results and the sample average was recalculated using the remaining runs. The averaged results for all samples, including the number of averaged runs and the standard deviation of the averaged results were summarized in an Excel workbook with each core on its own tab. A comma-separated values data file containing the tabular data in plain text is included in the download file. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_GrainSize.zip

   Date: 2018 (process 9 of 10)

   Dried, ground sediment from the 1-cm depth intervals of the 8 push cores were analyzed for the detection of radionuclides by standard gamma-ray spectrometry (Cutshall and Larsen, 1986) at the USGS SPCMSC radioisotope lab. Intervals from the uppermost 30 cm were analyzed from each core with alternating intervals analyzed from lower depths in the cores. A total of 306 depth intervals were analyzed for radioisotopic activities. The sediments (3.3-30 g) were sealed in airtight polypropylene containers or polystyrene test tubes. Sediments placed in the test tubes were sealed with a layer of epoxy. The sample weights and counting container geometries were matched to pre-determined calibration standards. The sealed samples were stored for a minimum of 3 weeks prior to analysis to allow Ra-226 to come into secular equilibrium with its daughter isotopes Pb-214 and Bi-214. The sealed samples were then counted for 48-72 hours on a 16 x 40-mm well or 50-mm diameter planar-style, low energy, high-purity germanium, gamma-ray spectrometer. The suite of naturally-occurring and anthropogenic radioisotopes measured along with their corresponding photopeak energies in kiloelectron volts (keV) are Pb-210 (46.5 keV), Th-234 (63.3 keV), Pb-214 (295.7 and 352.5 keV; proxies for Ra-226), Bi-214 (609.3 keV; proxy for Ra-226), Cs-137 (661.6 keV), and K-40 (1640.8 keV). Sample count rates were corrected for detector efficiency determined with International Atomic Energy Agency RGU-1 reference material, standard photopeak intensity, and self-absorption using a U-238 sealed source (planar detectors only, Cutshall and others, 1983). All activities, with the exception of short-lived Pb-214 and Bi-214, were decay-corrected to the date of field collection. The radioisotopic activities reported in the Excel spreadsheet include the counting error for all samples, results from each core are on its own tab. The critical level is reported for each core. A comma-separated values data file containing the tabular data in plain text is included in the download file. Person who carried out this activity:
   

   U.S. Geological Survey St. Petersburg Coastal and Marine Science Center

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   mmarot@usgs.gov

   Data sources produced in this process:

   • 16CCT07_GammaSpectroscopy.zip

   Date: 13-Oct-2020 (process 10 of 10)

   Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: VeeAnn A. Cross

   Marine Geologist

   384 Woods Hole Road

   Woods Hole, MA
   

   508-548-8700 x2251 (voice)

   508-457-2310 (FAX)

   vatnipp@usgs.gov

3. What similar or related data should the user be aware of?
   DeWitt, N.T., Stalk, C.A., Smith, C.G., Locker, S.D., Fredericks, J.J., McCloskey, T.A., and Wheaton, C.J., 2017, Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi: U.S. Geological Survey Data Series 1070.

   Online Links:

   • https://doi.org/10.3133/ds1070

   Stalk, C.A., Fredericks, J.J., Locker, S.D., and Carlson, C.S., 2018, Multibeam bathymetry data collected in 2016 from Grand Bay Alabama/Mississippi: U.S. Geological Survey data release doi.org/10.5066/F7MC8Z9N.

   Online Links:

   • https://doi.org/10.5066/F7MC8Z9N

   Locker, S.D., Forde, A.S., and Smith, C.G., 2018, Subbottom and sidescan sonar data acquired in 2015 from Grand Bay, Mississippi and Alabama: U.S. Geological Survey data release doi.org/10.5066/P9374DKQ.

   Online Links:

   • https://doi.org/10.5066/P9374DKQ

   Haller, Christian, Osterman, L.E., Smith, C.G., McCloskey, T.A., Marot, M.E., Ellis, A.M, and Adams, C.S., 2018, Benthic foraminiferal data from the eastern Mississippi Sound salt marshes and estuaries: U.S. Geological Survey data release doi.org/10.5066/F7MC8X5F.

   Online Links:

   • https://doi.org/10.5066/F7MC8X5F

   Haller, Christian, Smith, C.G., McCloskey, T.A., Marot, M.E., Ellis, A.M., and Adams, C.S., 2018, Benthic foraminiferal data from sedimentary cores collected in the Grand Bay (Mississippi) and Dauphin Island (Alabama) salt marshes: U.S. Geological Survey data release doi.org/10.5066/F7445KSG.

   Online Links:

   • https://doi.org/10.5066/F7445KSG

   Blott, S.J. and Pye, K., 2001, Gradistat: A grain size distribution and statistics package for the analysis of unconsolidated sediments: Earth Surface Processes and Landforms Volume 26.

   Online Links:

   • http://www.kpal.co.uk/gradistat.html

   Other_Citation_Details: Pages 1237-1248
   

   Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 1983, Direct analysis of 210Pb in sediment samples: self-absorption corrections: Nuclear Instruments and Methods Volume 206, Issues 1-2.

   Online Links:

   • https://doi.org/10.1016/0167-5087(83)91273-5

   Other_Citation_Details: Pages 309-312
   

   Cutshall, N.H. and Larsen, I.L., 1986, Calibration of a portable intrinsic Ge gamma-ray detector using point sources and testing for field applications: Health Physics Volume 51.

   Online Links:

   • https://doi.org/10.1097/00004032-198607000-00004

   Other_Citation_Details: Pages 53-59
   

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?
   The accuracy of the position and elevation data at the sample locations was determined during data collection. It is a function of the benchmark horizontal and vertical accuracy, and the quality of the raw DGPS position data recorded by the DGPS receiver and antenna. Benchmarks for the base stations were selected based upon the reported positional accuracy of a benchmark and the distance between sample sites (rover antenna) and base station. For this survey, the distance was kept within 8 kilometers (km). The final position and associated accuracy of the sample locations were determined through post-processing the DGPS trajectory between the base DGPS and the rover DGPS using Waypoint Product Group's GrafNav software version 8.7. All base station positions, respective antenna profiles, antenna height offsets, and recording intervals were accounted for in post-processing. Replicate analyses of loss on ignition are reported for quality assurance. The grain size data represent the sample averages for a subset of the statistical parameters calculated by GRADISTAT. The number of runs included in the averaged results are reported, and the standard deviation of the averaged results are reported for most parameters. The gamma spectroscopic radioisotope activities reported include the counting error for all samples. The critical level for gamma spectroscopy is reported for each core set.
2. How accurate are the geographic locations?
   All static GPS base station sessions were processed through the On-Line Positioning User Service (OPUS) maintained by the National Geodetic Survey (NGS). The OPUS base station solutions were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height) for each base station. Base station positional error was calculated as the absolute value of the final position minus the session position value. The maximum horizontal error of the base station coordinates used for post-processing the sample locations was 0.00081 seconds latitude and 0.00063 seconds longitude for benchmark B166, and 0.00054 seconds latitude and 0.00036 seconds longitude for benchmark 189A.
3. How accurate are the heights or depths?
   All static GPS base station sessions were processed through OPUS. The OPUS base station solutions were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height) for each base station. Base station positional error for each GPS session was calculated as the absolute value of the final position minus the session position value. For this survey, the maximum standard deviation of the base station ellipsoid heights were 0.021 m for B166 and 0.012 m for 189A. The maximum vertical error and standard deviation for the base stations B166 and 189A were +/- 0.028 m, 0.007 m and +/- 0.029 m, 0.011 m, respectively. All sample locations were post-processed to the base station coordinates.
4. Where are the gaps in the data? What is missing?
   This dataset is considered complete for the information presented, as described in the abstract section. 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?
   The grain-size sample runs in the GRADISTAT output files for which the mean Folk and Ward grain size varied from the set average by more than 1.5 standard deviations are highlighted in yellow and were not included in final averaged results. No formal logical accuracy tests were conducted on the remaining datasets.

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:

The U.S. Geological Survey requests that it be acknowledged as the originator of this dataset in any future products or research derived from these data.

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center

   Attn: Marci E. Marot

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   mmarot@usgs.gov
2. What's the catalog number I need to order this data set? Downloadable data
3. What legal disclaimers am I supposed to read?

   This publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	These zip archives includes Microsoft Excel spreadsheets, comma-separated values text files, Portable Document Format (PDF) image files, and accompanying metadata for sediment data from push cores collected from Grand Bay, Alabama/Mississippi in October 2016 (USGS FAN 2016-358-FA, project ID 16CCT07). in format Compressed (zip) archive Multimedia presentation
     Network links:	https://coastal.er.usgs.gov/data-release/doi-P9FO8R3Y/data/16CCT07_SiteInformation.zip https://coastal.er.usgs.gov/data-release/doi-P9FO8R3Y/data/16CCT07_SedimentPhysicalProperties.zip https://coastal.er.usgs.gov/data-release/doi-P9FO8R3Y/data/16CCT07_GrainSize.zip https://coastal.er.usgs.gov/data-release/doi-P9FO8R3Y/data/16CCT07_GammaSpectroscopy.zip

   • Cost to order the data: None, if obtained online

5. What hardware or software do I need in order to use the data set?

   The data tables for USGS FAN 2016-358-FA (project ID 16CCT07) were created in Microsoft Excel 2010 and can be opened using Microsoft Excel 2007 or higher; these data may also be viewed using the free Microsoft Excel Viewer (http://office.microsoft.com/). The data tables are also provided as comma-separated values text files (.csv). The .csv data file contains the tabular data in plain text and may be viewed with a standard text editor. Portable Document Format (PDF) files can be viewed using the free software Adobe Acrobat Reader (http://get.adobe.com/reader).

Who wrote the metadata?

Dates:

Last modified: 13-Oct-2020

Metadata author:

U.S. Geological Survey

Attn: Marci E. Marot

Geologist

600 4th Street South

St. Petersburg, FL

USA

727-502-8000 (voice)

mmarot@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)