Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi (21CCT02)

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What does this data set describe?

1. How might this data set be cited?
   Ellis, Alisha M., Smith, Christopher G., Vargas, Joseph M., Everhart, Cheyenne S., Terrano, Joseph F., Smith, Kathryn E.L., and Griffiths, Jonathan P., 20250624, Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi (21CCT02):.

   This is part of the following larger work.
   Ellis, Alisha M., Smith, Christopher G., Vargas, Joseph M., Everhart, Cheyenne S., Terrano, Joseph F., Smith, Kathryn E.L., and Griffiths, Jonathan P., 20210605, Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi: U.S. Geological Survey data release doi:10.5066/P9XYDHFZ, U.S. Geological Survey - St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

   Online Links:

   • https://doi.org/10.5066/P9XYDHFZ

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.45009
   East_Bounding_Coordinate: -88.40274
   North_Bounding_Coordinate: 30.36769
   South_Bounding_Coordinate: 30.32135
   

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

   Calendar_Date: 04-Aug-2021

   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?

   21CCT02_SiteInformation.csv, 21CCT02_SiteInformation.xlsx

   Comma-separated values text file (.csv) and Microsoft Excel workbook defining the field sampling dates, site locations, elevations, water depths, core lengths and compaction, and water quality parameters for the push cores collected in this study (USGS FAN 2021-320-FA, alternate FAN/project ID 21CCT02). Some values in the .csv file display as dates due to csv formatting, and no data values are indicated with a hyphen. (Source: USGS)

   Alternate FAN

   Alternate field activity number assigned by the USGS to the sample collection. (Source: USGS)

   Value	Definition
   21CCT02	Alternate FAN (FAN 2021-320-FA).

   Sample ID

   Sample identifier assigned by USGS scientist consisting of GB to indicate Grand Bay and a three-digit number. (Source: USGS) Character string

   Sample Type Collected

   Additional sample identifier designations appended to identify sample type collected at a single site. For some sites, multiple sample types were collected, which is designated by a letter and space between each sample type. (Source: USGS)

   Value	Definition
   M	Marsh push core
   R	Russian peat auger core

   Transect Site ID

   Marsh samples were collected along shore perpendicular transects, with each transect referred to as a site number. (Source: USGS) Sample sites include Site 7 and 9.

   Distance from Shoreline (m)

   Distance, in meters, from the shoreline where the samples at that site were collected. (Source: USGS)

   Range of values
   Minimum:	20
   Maximum:	50
   Units:	meters

   Date Collected

   Date identifier (Source: USGS)

   Range of values
   Minimum:	08/04/21
   Maximum:	08/04/21
   Units:	mm/dd/yy

   Latitude (NAD83)

   Latitude of station location, in decimal degrees (North American Datum of 1983). (Source: USGS)

   Range of values
   Minimum:	30.33677
   Maximum:	30.34447
   Units:	Decimal degrees
   Resolution:	0.00001

   Longitude (NAD83)

   Longitude of site location, in decimal degrees (North American Datum of 1983). (Source: USGS)

   Range of values
   Minimum:	-88.44894
   Maximum:	-88.44667
   Units:	Decimal degrees
   Resolution:	0.00001

   Elevation

   The elevation, in meters, of each site relative to the North American Datum of 1988 GEOID12A. (Source: USGS)

   Range of values
   Minimum:	0.325
   Maximum:	0.404
   Units:	meters
   Resolution:	0.001

   Water Depth (m)

   The depth of the water recorded at each estuarine site, in meters. (Source: USGS)

   Range of values
   Minimum:	1.5
   Maximum:	1.5
   Units:	meters
   Resolution:	0.1

   Field Estimated Recovered Core Length (cm)

   The approximate length of the push core collected, in centimeters, as recorded in the field. (Source: USGS)

   Range of values
   Minimum:	28.2
   Maximum:	44.2
   Units:	centimeters
   Resolution:	0.2

   Coring Compaction (cm)

   The approximate amount of compaction withstood by the push core, in centimeters, as recorded in the field. (Source: USGS)

   Range of values
   Minimum:	2.7
   Maximum:	9.2
   Units:	centimeters
   Resolution:	0.1

   Core Diameter (cm)

   The diameter of the acrylic core barrel used to collect the push cores, in centimeters. (Source: USGS)

   Range of values
   Minimum:	10.16
   Maximum:	10.16
   Units:	centimeters
   Resolution:	0.01

   Number Auger Sections (N)

   The total number of 50-centimeter sections of Russian Peat Augers collected at each station. (Source: USGS)

   Range of values
   Minimum:	3
   Maximum:	4
   Units:	Number of 50-centimeter sections
   Resolution:	1.0

   Recovered Auger Length (cm)

   The total length of the Russian Peat Auger collected at each site in centimeters, as recorded in the field. (Source: USGS)

   Range of values
   Minimum:	109.0
   Maximum:	160.0
   Units:	centimeters
   Resolution:	0.5

   Marsh Unit Thickness (cm)

   The estimated vertical extent/depth of the marsh unit, in centimeters. (Source: USGS)

   Range of values
   Minimum:	109
   Maximum:	129
   Units:	centimeters
   Resolution:	1.0

   Elevation of Basal Marsh Contact (m, NAVD88 GEOID12A)

   The estimated elevation of the basal marsh contact, in meters, at each site relative to the North American Vertical Datum of 1988 GEOID12A. (Source: USGS)

   Range of values
   Minimum:	-0.944
   Maximum:	-0.746
   Units:	meters
   Resolution:	0.001

   21CCT02_SedimentPhysicalProperties.csv, 21CCT02_SedimentPhysicalProperties.xlsx

   Comma-separated values text file (.csv) and Microsoft Excel workbook listing water content, porosity, dry bulk density (DBD) and loss-on-ignition (LOI) data for sediment cores collected on and around Point aux Chenes marsh, Mississippi (USGS FAN 2021-320-FA, alternate FAN/project ID 21CCT02). The results for each core are provided on its own tab. Some values in the .csv file display as dates due to csv formatting, and no data values are indicated with a hyphen. (Source: USGS)

   Core ID

   Core identifier assigned by a USGS scientist. (Source: USGS) Identifier consists of alternate FAN (21CCT02), hyphen, sample ID (GB####), hyphen, sample type (M = marsh push core), hyphen, PP (physical parameters subsample). A, B, and C indicate laboratory replicates of a single sample.

   Depth (cm)

   Depth interval in centimeters measured below the core surface, A, B, and C indicates laboratory replicate. (Source: USGS)

   Range of values
   Minimum:	0-1
   Maximum:	40-41.2
   Units:	centimeters
   Resolution:	0.2

   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:	0.39
   Maximum:	0.76
   Units:	Grams of water per grams 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:	0.25
   Maximum:	0.91
   Units:	Grams per cubic centimeter
   Resolution:	0.01

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

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

   Range of values
   Minimum:	0.06
   Maximum:	0.79
   Units:	Grams of organic matter per grams of dry sediment
   Resolution:	0.01

   21CCT02_GammaSpectroscopy.csv, 21CCT02_GammaSpectroscopy.xlsx

   Comma-separated values text file (.csv) and Microsoft Excel workbook summarizing the total cesium-137, lead-210, radium-226, thorium-234, potassium-40, and their associated errors for each depth interval for the sediment cores collected from the Point aux Chenes marsh, Mississippi (USGS FAN 2021-320-FA, alternate FAN/project ID 21CCT02). The results are provided for each core on its own tab. Some values in the .csv file display as dates due to csv formatting, no data values are indicated with a double hyphen, and values of ND indicate not detected. (Source: USGS)

   21CCT02_GammaSpectroscopy.csv

   Comma-separated values text file summarizing the total cesium-137, lead-210, radium-226, thorium-234, potassium-40, and their associated errors for each depth interval for the sediment cores collected from the Point aux Chenes marsh, Mississippi (USGS FAN 2021-320-FA, alternate FAN/project ID 21CCT02). (Source: USGS)

   Core ID

   Core identifier assigned by a USGS scientist. (Source: USGS) Identifier consists of alternate FAN (21CCT02), hyphen, sample ID (GB####), hyphen, sample type (M = marsh push core).

   Depth (cm)

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

   Range of values
   Minimum:	0-1
   Maximum:	39-40
   Units:	centimeters
   Resolution:	1.0

   Cs-137 (dpm/g)

   The total activity of cesium-137 for each centimeter interval of every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.10
   Maximum:	1.30
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

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

   The counting error associated with the total activity of cesium-137 for each centimeter interval for every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.04
   Maximum:	0.13
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Pb-210 (dpm/g)

   The total activity of lead-210 for each centimeter interval of every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	1.82
   Maximum:	8.34
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

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

   The counting error associated with the total activity of lead-210 for each centimeter interval for every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.19
   Maximum:	0.39
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Ra-226 (dpm/g)

   The total activity of radium-226 for each centimeter interval of every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	1.17
   Maximum:	1.95
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

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

   The counting error associated with the total activity of radium-226 for each centimeter interval for every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.07
   Maximum:	0.13
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Th-234 (dpm/g)

   The total activity of thorium-234 for each centimeter interval of every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	1.81
   Maximum:	7.27
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

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

   The counting error associated with the total activity of thorium-234 for each centimeter interval for every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.23
   Maximum:	0.52
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   K-40 (dpm/g)

   The total activity of potassium-40 for each centimeter interval of every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	4.68
   Maximum:	22.09
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

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

   The counting error associated with the total activity of potassium-40 for each centimeter interval for every core in disintegrations per minute per gram of sediment. (Source: USGS)

   Range of values
   Minimum:	0.78
   Maximum:	1.79
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   Entity_and_Attribute_Overview:

   The processed x-ray images of each marsh push core are provided for non-quantitative purposes only (18CCT09_21CCT02_Xrays.zip).

   Entity_and_Attribute_Detail_Citation:

   The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

   Entity_and_Attribute_Overview:

   The detailed attribute descriptions for the grain-size workbooks are provided in the included data dictionary (GrainSize_DataDictionary.docx). Comma-separated values text file (.csv) and Microsoft Excel workbook (.xlsx) summarizing grain-size parameters for each surface sample and centimeter depth interval from the sediment cores collected on the Point aux Chenes marshes (USGS FAN 2021-320-FA [21CCT02]). 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. These metadata are not complete without this file.

   Entity_and_Attribute_Detail_Citation:

   The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Alisha M. Ellis
   • Christopher G. Smith
   • Joseph M. Vargas
   • Cheyenne S. Everhart
   • Joseph F. Terrano
   • Kathryn E.L. Smith
   • Jonathan P. Griffiths
2. Who also contributed to the data set?
   U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
3. To whom should users address questions about the data?
   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@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: 2021 (process 1 of 10)

   At 2 sites on the Point aux Chenes marsh, push cores (GB537M, GB572M) were collected with 10.16-cm diameter polycarbonate barrels. Upon retrieval, similar to methods described in Osbourne and DeLaune (2013; with the exception of not adding water for extraction when not necessary due to the sediments being saturated) and calculation of compaction due to coring, the cores were visually inspected for disturbances (i.e., slumping, washout, scouring, cracking, bubbling, and/or discontinuities) to ensure the core was intact and representative of the site. If the core appeared disturbed, it was discarded, and a new core was collected and inspected. The cores were transported upright, in order to avoid slumping and preserve the natural sediment orientation, to the SPCMSC laboratory for sectioning. At each marsh site, Russian peat augers were collected in agreement with the methods described in Osbourne and DeLaune (2013) and manufacturer recommendations. Visual characteristics of the peat augers were described (i.e., general color, visual organic matter texture and type such as roots, bivalves, and level of decomposition, and sediment texture such as sandy silt or clayey silt) and thickness of the upper organic-bearing unit (peat) was recorded in field logs, in centimeters. Once described and photographed horizontally with a scale bar and label, peat augers were discarded in the field. The field logs associated with those peat augers are available upon request. Sample identifiers consist of the USGS alternate FAN or project ID (21CCT02), a site-specific identifier (for example, GB572), and appended with an alphabetic identifier to differentiate the sediment collection method (M for marsh push core, R for Russian peat auger). Push core locations were initially recorded at the time of collection using a Garmin GPSMAP 76S or Garmin 62stc handheld GPS receiver. Marsh site coordinates were also recorded using a GPS antenna with base station set up. Site location information includes sample type, date collected, location relative to the shoreline, latitude, longitude, elevation, core lengths, and YSI measurements, which are reported in an Excel spreadsheet (.xlsx). Comma-separated values (.csv) 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, St. Petersburg Coastal and Marine Science Center

   Attn: Joseph F. Terrano

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   jterrano@usgs.gov

   Data sources produced in this process:

   • 21CCT02_SiteInformation.csv
   • 21CCT02_SiteInformation.xlsx

   Date: 2021 (process 2 of 10)

   A Trimble R10 GNSS and TSC3 data collector were used to collect global positioning system (GPS) coordinates and elevations. Both the R10 and TSC3 were mounted onto a 2-m graphite rod with a mounted foot to keep the rod on the surface of the marsh. A projected coordinate system (NAD_1983_StatePlane_Mississippi_East_FIPS_2301) was used for data collection. At marsh core sites, the "Measure Points" tool was used. Data were exported from the TSC3 as a shapefile (.shp). The .shp was pulled from the export folder and brought into ArcGIS software where the projection was defined as NAD_1983_StatePlane_Mississippi_East_FIPS_2301 (ESRI:102694). Elevation data were sent to the USGS SPCMSC as ArcGIS shapefiles. Within ArcMap, the data were reprojected from NAD_1983_StatePlane_Mississippi_East_FIPS_2301 into NAD_1983_UTM_Zone_16N (North American Datum of 1983 Universal Transverse Mercator Zone 16 North), using the "reproject" geoprocessing tool. The final shapefile was exported into tabular digital data format (Comma Separated Values [CSV]). Person who carried out this activity:
   

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

   Attn: Joseph F. Terrano

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   jterrano@usgs.gov

   Data sources produced in this process:

   • 21CCT02_SiteInformation.csv
   • 21CCT02_SiteInformation.xlsx

   Date: 2021 (process 3 of 10)

   Upon return from the field, all marsh push cores were X-rayed vertically using a stand, to avoid sediment slumping, onto an iCRco 11 x 14-inch cassette using an Ecotron EPX-F2800 X-ray unit at a distance of 79 cm for a 1:1.015 ratio. The cassette was inserted into and scanned using an iCR3600+ cassette scanner and processed using iCRco QPC XSCAN32 version 2.10. Images were exported as Tag Image File Format (.tiff) files and edited in Adobe Photoshop, using grayscale color inversion, and inserting a reference scale bar. X-ray images were used as visual aids prior to extrusion and subsampling to assess peat thickness in comparison with peat augers, presence of macrofossils which may impede sectioning, and to ensure cores are intact for the length of the core. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@usgs.gov

   Data sources produced in this process:

   • 18CCT09_21CCT02_Xrays.zip

   Date: 2021 (process 4 of 10)

   Following x-raying, all cores were vertically extruded and sectioned into 1-cm intervals using a serrated knife, pre-measured polycarbonate ring, and extruder (in accordance with methods described in Osbourne and DeLaune, 2013 and in 1-cm intervals as is standard for sediment and radiochemical analyses; Nittrouer and others, 1979) at the USGS SPCMSC sediment core laboratory. The outer circumference of each sample interval was removed to avoid use of sediment that was in contact with the polycarbonate barrel which could result in contamination by sediment from other depths due to movement within the barrel both during collection and extruding; each sediment interval was bagged in a zipped baggie, homogenized, and refrigerated (Osbourne and DeLaune, 2013). Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@usgs.gov

   Date: 2021 (process 5 of 10)

   In the laboratory, marsh core samples were homogenized in the sample bag to ensure a representative subsample from the 1-cm interval (Reddy and others, 2013), and the subsample for sediment parameters was extracted and processed for basic sediment characteristics: dry bulk density and porosity. Water content, porosity, and dry bulk density were calculated by determining water mass lost during drying. To calculate, known volumes of each wet subsample, usually 30-60 milliliters (mL), were packed into a graduated syringe with 0.5 cubic centimeter (cm^3) resolution. The wet sediment sample was then extruded into a pre-weighed aluminum tray/weigh boat, and the weight was recorded. The wet sediment sample and tray were placed in a drying oven for 48 hours at 60 °C to remove water content. A 1 mL split from the original wet sample was also taken for diatom analysis and was dried using the same procedure. Water content (θ) was determined as the mass of water (lost when dried) relative to the initial wet sediment mass. Porosity (φ) was estimated 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), representative of a silty quartz sand. Salt-mass contributions were removed based on the salinity measured at the time of sample collection. If salinity was not measured in the field, pore water salinity was estimated to be 25 (Sharma and others, 1987; Gardner and Wilson, 2006). Dry bulk density (g/cm^3) was determined by the ratio of dry sediment to the known volume of sediment packed into the syringe. Water content, porosity and dry bulk density are reported in the Excel spreadsheet (.xlsx). A comma-separated values (.csv) data file containing the tabular data in plain text is included in the download file. Some depth intervals in the .csv file display as dates due to csv formatting. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@usgs.gov

   Data sources produced in this process:

   • 21CCT02_SedimentPhysicalProperties.csv
   • 21CCT02_SedimentPhysicalProperties.xlsx

   Date: 2023 (process 6 of 10)

   Organic matter (OM) content was determined with a mass loss technique referred to as loss on ignition (LOI). The dry sediment subsample from the previous process step, measuring dry bulk density, was homogenized with a porcelain mortar and pestle. Approximately 2 to 6 grams (g) of the dry sediment was placed into a pre-weighed porcelain crucible. The mass of the dried sediment was recorded with a precision of 0.01 g on an analytical balance. The sample was then placed inside a laboratory muffle furnace with stabilizing temperature control. The furnace was heated to 110 °C (Celsius) for a minimum of 6 hours to remove hygroscopic water adsorbed onto the sediment particles. The furnace temperature was then lowered to 60 °C, at which point the sediments could be reweighed safely (modified from Dean, 1974 who heated the furnace to 100 °C for 1 hour). The dried sediment was returned to the muffle furnace and heated to 550 °C over a period of 30 minutes and kept at 550 °C (Galle and Runnels, 1960) for 6 hours (optimal exposure times for complete combustion of organic carbon are reported ranging between 1–12 hours; Dean, 1974; Wang and others, 2011; Heiri and others, 2001; Santisteban and others, 2004). Following the 6-hour burn time for removal of organic carbon, the furnace's temperature was lowered to 60 °C, at which point the sediments could be reweighed safely while preventing 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 OM content (Dean, 1974). Approximately 12.3 percent of the field samples were run in triplicate for LOI to assess precision. 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 are reported for quality assurance in the Excel spreadsheet (.xlsx). A comma-separated values (.csv) data file containing the tabular data in plain text is included in the download file. Some depth intervals in the .csv file display as dates due to csv formatting. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@usgs.gov

   Data sources produced in this process:

   • 21CCT02_SedimentPhysicalProperties.csv
   • 21CCT02_SedimentPhysicalProperties.xlsx

   Date: 2023 (process 7 of 10)

   Dried, ground sediment from the 1-cm depth intervals of 2 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 40 cm were analyzed from each core. The sediments were sealed in airtight polypropylene containers for planar detectors or polystyrene test tubes for the well detector. 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 radium-226 (Ra-226) to come into secular equilibrium with its daughter isotopes lead-214 (Pb-214) and bismuth-214 (Bi-214). The sealed samples were then counted for 48-72 hours on a 16 x 40-millimeter well or 50-millimeter 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), thorium-234 (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), cesium-137 (Cs-137; 661.6 keV), and potassium-40 (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 uranium-238 (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 (.xlsx) 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 (.csv) data file containing the tabular data in plain text is included in the download file. Some depth intervals in the .csv file display as dates due to csv formatting. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Christopher G. Smith

   Research Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cgsmith@usgs.gov

   Data sources produced in this process:

   • 21CCT02_GammaSpectroscopy.csv
   • 21CCT02_GammaSpectroscopy.xlsx

   Date: 2024 (process 8 of 10)

   Particle size analysis was performed on selected 1-cm depth intervals for the 10 marsh push cores, based on dry bulk density variations down-core, and on all 23 surficial sediment samples. Prior to analyses, sediment samples were digested with 8 mL of 30 percent hydrogen peroxide (H2O2) overnight to remove excess organics (Poppe and others, 2000). The H2O2 was then evaporated slowly on a hot plate, and the sediment was 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 four 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). Person who carried out this activity:
   

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

   Attn: Cheyenne S. Everhart

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ceverhart@usgs.gov

   Data sources produced in this process:

   • 21CCT02_GrainSize.csv
   • 21CCT02_GrainSize.xlsx

   Date: 2024 (process 9 of 10)

   The raw grain-size data were processed with the free software program, GRADISTAT version 8, (Blott and Pye, 2001; kpal.co.uk/gradistat), which calculates the mean, median, sorting, skewness, and kurtosis of each sample geometrically in metric units and logarithmically in phi units (Φ) (Krumbein, 1934) using a modified Folk and Ward (1957) scale. GRADISTAT also calculates the fraction of sediment from each sample by size category (for example, clay, coarse silt, fine sand) based on Friedman and Saunders (1978), a modified Wentworth (1922) size scale. A macro function in Microsoft Excel, developed by the USGS SPCMSC, was applied to the data to calculate the average and standard deviation for each sample set (8 runs per sample), and highlight runs that varied from the set average by more than ± 1.5 standard deviations. 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 (.xlsx) with each core on its own tab. A comma-separated values (.csv) data file containing the tabular data in plain text is included in the download file. The individual run statistics for all sites, prior to averaging, is available upon request. Some depth intervals in the .csv file display as dates due to csv formatting. Person who carried out this activity:
   

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

   Attn: Cheyenne S. Everhart

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   ceverhart@usgs.gov

   Data sources produced in this process:

   • 21CCT02_GrainSize.csv
   • 21CCT02_GrainSize.xlsx

   Date: 24-Jun-2025 (process 10 of 10)

   Version 3.0: This data release was versioned in June 2025, to add new co-authors, grain-size information (21CCT02 only), and other required versioning changes to the metadata record. Metadata contact information with Alisha Ellis as the primary contact was changed to Christopher Smith. Person who carried out this activity:
   

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

   Attn: Joseph F. Terrano

   Physical Scientist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   jterrano@usgs.gov

3. What similar or related data should the user be aware of?
   Blott, S.J. and Pye, K., 20010928, Gradistat: A grain size distribution and statistics package for the analysis of unconsolidated sediments: Earth Surface Processes and Landforms Volume 26, Issue 11.

   Online Links:

   • https://doi.org/10.1002/esp.261
   • http://www.kpal.co.uk/gradistat.html

   Other_Citation_Details: Pages 1237-1248
   

   Cutshall, N.H., and Larsen, I.L., 198607, Calibration of a portable intrinsic Ge gamma-ray detector using point sources and testing for field applications: Health Physics Volume 51, Issue 1.

   Online Links:

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

   Other_Citation_Details: Pages 53-59
   

   Osbourne, T.Z., and DeLaune R.D., 20131018, Soil and sediment sampling of inundated environments: Methods in Biogeochemistry of Wetlands Volume 10.

   Online Links:

   • https://doi.org/10.2136/sssabookser10.c2

   Other_Citation_Details: Pages 21-41
   

   Cutshall, N.H., Larsen, I.L., and Olsen, C.R., 19830215, Direct analysis of Pb-210 in sediment samples: self-absorption corrections: Nuclear Instruments and Methods in Physics Research Volume 206, Issues 1-2.

   Online Links:

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

   Other_Citation_Details: Pages 309-312
   

   Folk, R.L., and Ward, W.C., 19570301, Brazos River Bar: A study in the significance of grain size parameters: Journal of Sedimentary Petrology Volume 27, No. 1.

   Online Links:

   • https://doi.org/10.1306/74D70646-2B21-11D7-8648000102C1865D

   Other_Citation_Details: Pages 3-26
   

   Krumbein, W.C., 19340801, Size frequency distributions of sediments: Journal of Sedimentary Petrology Volume 4, No. 2.

   Online Links:

   • https://doi.org/10.1306/D4268EB9-2B26-11D7-8648000102C1865D

   Other_Citation_Details: Pages 65-77
   

   Wentworth, C.K., 1922, A scale of grade and class terms for clastic sediments: Journal of Geology Volume 30, No. 5.

   Online Links:

   • https://www.jstor.org/stable/30063207

   Other_Citation_Details: Pages 377-392
   

   Dean, W.E., 19740301, Determination of carbonate and organic matter in calcareous sediments and sediment rocks by loss on ignition: comparison with other methods: Journal of Sedimentary Petrology Volume 44, No. 1.

   Online Links:

   • https://doi.org/10.1306/74D729D2-2B21-11D7-8648000102C1865D

   Other_Citation_Details: Pages 242-248
   

   Friedman, G.M., and Saunders, J.E., 1978, Principles of Sedimentology.

   Other_Citation_Details: 792 pages
   

   Nittrouer, C.A., Sternberg, R.W., Carpenter, R., and Bennett, J.T., 197905, The use of Pb-210 geochronology as a sedimentological tool: application to the Washington continental shelf: Marine Geology Volume 31, Issues 3-4.

   Online Links:

   • https://doi.org/10.1016/0025-3227(79)90039-2

   Other_Citation_Details: Pages 297-316
   

   Reddy, K.R., Clark, M.W., DeLaune, R.D., and Kongchum, M., 20131018, Physicochemical characterization of wetland soils: Methods in biogeochemistry of wetlands Volume 10, Chapter 3.

   Online Links:

   • https://doi.org/10.2136/sssabookser10.c3

   Other_Citation_Details: Pages 41-54
   

   Sharma, P., Gardner, L.R., Moore, W.S., Bollinger, M.S., 198703, Sedimentation and bioturbation in a salt marsh as revealed by 210Pb, 137Cs, and 7Be studies: Limnology and Oceanography Volume 32, Issue 2.

   Online Links:

   • https://doi.org/10.4319/lo.1987.32.2.0313

   Other_Citation_Details: Pages 313-326
   

   Gardner, L.R., and Wilson, A.M., 200609, Comparison of four numerical models for simulating seepage from salt marsh sediments.: Estuarine, Coastal and Shelf Science Volume 69, Issue 3-4.

   Online Links:

   • https://doi.org/10.1016/j.ecss.2006.05.009

   Other_Citation_Details: Pages 427-437
   

   Galle, O.K., and Runnels, R.T., 19601201, Determination of CO2 in carbonate rocks by controlled loss on ignition: Journal of Sedimentary Petrology Volume 30, No. 4.

   Online Links:

   • https://doi.org/10.1306/74D70ABF-2B21-11D7-8648000102C1865D

   Other_Citation_Details: Pages 613-618
   

   Poppe, L.J., Eliason, A.H., Fredericks, J.J., Rendigs, R.R., Blackwood, D., and Polloni, C.F., 2000, CHAPTER 1: Grain-size analysis of marine sediments: methodology and data processing: U.S. Geological Survey Open-File Report 00-358.

   Online Links:

   • https://pubs.usgs.gov/of/2000/of00-358/text/chapter1.htm

   Santisteban, J.I., Mediavilla, R., Lopez-Pamo, E., Dabrio, C.J., Blanca Ruiz Zapata, M., Garcia, M.J.G., Castano, S., and Martinez-Alfaro, P.E., 200410, Loss on ignition: a qualitative or quantitative method for organic matter and carbonate mineral content in sediments?: Journal of Paleolimnology Volume 32.

   Online Links:

   • https://doi.org/10.1023/B:JOPL.0000042999.30131.5b

   Other_Citation_Details: Pages 287-299
   

   Wang, Q., Li, Y., and Wang, Y., 201103, Optimizing the weight loss-on-ignition methodology to quantify organic and carbonate carbon of sediments from diverse sources: Environmental Monitoring and Assessment Volume 174.

   Online Links:

   • https://doi.org/10.1007/s10661-010-1454-z

   Other_Citation_Details: Pages 241-257
   

   Heiri, O., Lotter, A.F., and Lemcke, G., 200101, Loss on Ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results: Journal of Paleolimnology Volume 25.

   Online Links:

   • https://doi.org/10.1023/A:1008119611481

   Other_Citation_Details: Pages 101-110
   

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

1. How well have the observations been checked?
   Position and elevation data at each sample site were recorded with a Trimble R10 Global Navigation Satellite System (GNSS) and TSC3 data collector. The positional accuracy of the Trimble R10 GNSS has a horizontal error of +/-8 millimeters (mm) + 0.5 parts per million (ppm) root mean square (RMS) and a vertical error of +/-15 mm + 0.5 ppm RMS. 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. It is a known issue that the CSV text format for several depth intervals is incorrectly displayed when viewed. Instead of the depth being "01-02" it is displayed as "month-number" (January-2). This is caused by internal formatting of CSVs and can not be changed unless the CSV is converted back to an Excel document (xlsx).
2. How accurate are the geographic locations?
   +/-8 mm + 0.5 ppm RMS.
3. How accurate are the heights or depths?
   +/-15 mm + 0.5 ppm RMS.
4. Where are the gaps in the data? What is missing?
   This data release contains all sediment data associated with this USGS FAN and includes the geographic site location, sediment physical properties, grain-size statistics, and sediment radiochemistry activities for 2 cores collected at 2 sites on Point aux Chenes marsh and marsh surface and estuarine grab samples, collected in August 2021.
5. How consistent are the relationships among the observations, including topology?
   Position and elevation data at each sample site were recorded with a Trimble R10 GNSS system set to 1 s continuous topo for shorelines and 10 s static occupations for all other data points. At the start of each survey a baseline mark was collected at the same location at the Grand Bay NERR headquarters. The grain-size sample runs in the GRADISTAT output files for which the mean Folk and Ward (1957) 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?

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

   Attn: USGS SPCMSC Data Management

   600 4th Street South

   Saint Petersburg, FL
   

   United States

   727-502-8000 (voice)

   gs-g-spcmsc_data_inquiries@usgs.gov
2. What's the catalog number I need to order this data set? 21CCT02_SiteInformation.csv, 21CCT02_SiteInformation.xlsx, 21CCT02_SedimentPhysicalProperties.csv, 21CCT02_SedimentPhysicalProperties.xlsx, 21CCT02_GammaSpectroscopy.csv, 21CCT02_GammaSpectroscopy.xlsx, 21CCT02_GrainSize.csv, 21CCT02_GrainSize.xlsx, 21CCT02-GB537M_xray.jpg, 21CCT02-GB572M_xray.jpg, and GrainSize_DataDictionary.docx
3. What legal disclaimers am I supposed to read?
   Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product 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:

     This zip archive includes Microsoft Excel spreadsheets (.xlsx), comma-separated values text files (.csv), Joint Photographic Experts Group files (JPEG) and accompanying metadata for sediment data from cores collected from the Point aux Chenes marsh (USGS FAN 2021-320-FA). in format Comma-delimited text, Microsoft Excel format, JPEG, Microsoft Word format WinZip, 7-Zip

     Network links:

     https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_SiteInformation.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_SedimentPhysicalProperties.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_GrainSize.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_GammaSpectroscopy.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_FieldLogs.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_21CCT02_Xrays.zip

   • Cost to order the data: None

5. What hardware or software do I need in order to use the data set?
   The data tables for USGS FAN 2021-320-FA were created in Microsoft Excel and can be opened using Microsoft Excel 2007 or higher. 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.

Who wrote the metadata?

Dates:

Last modified: 24-Jun-2025

Metadata author:

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

Attn: USGS SPCMSC Data Management

600 4th Street South

Saint Petersburg, FL

United States

727-502-8000 (voice)

gs-g-spcmsc_data_inquiries@usgs.gov

Metadata standard:

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