Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi

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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., and Everhart, Cheyenne, 20210615, Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi:.

   This is part of the following larger work.
   Ellis, Alisha M., Smith, Christopher G., Vargas, Joseph M., and Everhart, Cheyenne S., 20210616, 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, 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?

   Beginning_Date: 23-Oct-2018

   Ending_Date: 26-Oct-2018

   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?

   18CCT09_SiteInformation.xlsx

   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 and surficial sediment samples collected in this study (USGS FAN 2018-358-FA, project ID 18CCT09). (Source: USGS)

   18CCT09_SiteInformation.csv

   Comma-separated values text file defining the field sampling dates, site locations, elevations, water depths, core lengths and compaction, and water quality parameters for the push cores and surficial sediment samples collected in this study (USGS FAN 2018-358-FA, project ID 18CCT09). (Source: USGS)

   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: M, marsh push core; R, Russian peat auger; G, estuarine ponar grab; S, marsh surface sample. (Source: USGS) Character string

   Transect Site ID

   Marsh samples were collected along shore perpendicular transects, with each transect referred to as a site. (Source: USGS) Character string

   Distance from Shoreline (m)

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

   Date Collected

   Date identifier (Source: USGS)

   Range of values
   Minimum:	10/23/18
   Maximum:	10/26/18
   Units:	mm/dd/yy

   Latitude (NAD83)

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

   Range of values
   Minimum:	30.32135
   Maximum:	30.36769
   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:	-88.45009
   Maximum:	-88.40274
   Units:	Decimal degrees
   Resolution:	0.00001

   Elevation (m, NAVD88 GEOID12A)

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

   Range of values
   Minimum:	0.350
   Maximum:	0.650
   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:	0.2
   Maximum:	3.3
   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:	36.0
   Maximum:	65.0
   Units:	centimeters
   Resolution:	0.5

   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:	2.0
   Maximum:	61.0
   Units:	centimeters
   Resolution:	0.5

   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:	0
   Maximum:	4
   Units:	Number of 50-centimeter sections
   Resolution:	1

   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:	100.0
   Maximum:	188.0
   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:	52
   Maximum:	144
   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:	-0.79
   Maximum:	-0.118
   Units:	meters
   Resolution:	1.000

   Temperature (°C)

   Water temperature in degrees Celsius at each site. (Source: YSI)

   Range of values
   Minimum:	20.9
   Maximum:	22.2
   Units:	Degrees Celsius
   Resolution:	0.1

   Barometric Pressure (mmHg)

   Barometric pressure, in millimeters of mercury, at each site. (Source: YSI)

   Range of values
   Minimum:	763.7
   Maximum:	765.3
   Units:	Millimeters of mercury
   Resolution:	0.1

   Dissolved Oxygen (%)

   Percent dissolved oxygen at each core location. (Source: YSI)

   Range of values
   Minimum:	7.89
   Maximum:	107.0
   Units:	Percent
   Resolution:	0.1

   Dissolved Oxygen (mg/L)

   Dissolved oxygen in milligrams per liter at each core location. (Source: YSI)

   Range of values
   Minimum:	7.2
   Maximum:	35.7
   Units:	Milligrams per liter
   Resolution:	0.1

   Specific Conductance (mS/cm)

   Specific conductance in millisiemens per centimeter at core location. (Source: YSI)

   Range of values
   Minimum:	36.7
   Maximum:	38.4
   Units:	Millisiemens per centimeter
   Resolution:	0.1

   Salinity

   Salinity at each core location. (Source: YSI)

   Range of values
   Minimum:	22.6
   Maximum:	25.6
   Units:	Practical salinity units
   Resolution:	0.1

   pH

   pH at each core location (Source: YSI)

   Range of values
   Minimum:	7.6
   Maximum:	7.9
   Units:	Hydrogen ion concentrations
   Resolution:	0.1

   pH (mV)

   pH in millivolts at each core location. (Source: YSI)

   Range of values
   Minimum:	-56.3
   Maximum:	-73.8
   Units:	Millivolts
   Resolution:	0.1

   Oxidation-Reduction Potential (mV)

   Oxidation-reduction potential in millivolts at each core location. (Source: YSI)

   Range of values
   Minimum:	82.0
   Maximum:	159.8
   Units:	Millivolts
   Resolution:	0.1

   Turbidity (NTU)

   Measurement of the amount of light that is scattered by material in the water, in nephelometric turbidity units. (Source: YSI)

   Range of values
   Minimum:	3.3
   Maximum:	10.5
   Units:	nephelometric turbidity units
   Resolution:	0.1

   18CCT09_SedimentPhysicalProperties.xlsx

   Microsoft Excel workbook listing water content, porosity, bulk density and loss-on-ignition data for sediment cores and surface samples collected on and around Point aux Chenes marsh, Mississippi (USGS FAN 2018-358-FA). The results for each core are provided on its own tab. (Source: USGS)

   18CCT09_SedimentPhysicalProperties.csv

   Comma-separated values text file listing water content, porosity, bulk density and loss-on-ignition data for sediment cores and surface samples collected on and around Point aux Chenes marsh, Mississippi (USGS FAN 2018-358-FA). (Source: USGS)

   Sample ID

   Sample identifier assigned by USGS scientist, S appended is for a marsh surface sample, G is for a petite ponar grab sample, PP indicates physical parameters subsample, A, B, and C indicate laboratory replicates of a single sample. (Source: USGS) Character string

   Core ID

   Core identifier assigned by USGS scientist, M indicates the sample is a marsh push core, PP indicates physical parameters subsample, A, B, and C indicate laboratory replicates of a single sample. (Source: USGS) Character string

   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:	71-72
   Units:	centimeters
   Resolution:	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:	0.17
   Maximum:	1.67
   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:	0.28
   Maximum:	1.58
   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:	0.00
   Maximum:	0.24
   Units:	Grams of organic matter per grams of dry sediment
   Resolution:	0.01

   18CCT09_GammaSpectroscopy.xlsx

   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 2018-358-FA). The results are provided for each core on its own tab. (Source: USGS)

   18CCT09_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 2018-358-FA). (Source: USGS)

   Core ID

   Core identifier assigned by USGS scientist; M indicates the sample is a marsh push core. (Source: USGS) Character string

   Depth (cm)

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

   Range of values
   Minimum:	0-1
   Maximum:	59-60
   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:	0.09
   Maximum:	1.62
   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:	0.03
   Maximum:	0.14
   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:	0.25
   Maximum:	8.03
   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:	0.08
   Maximum:	0.84
   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:	0.21
   Maximum:	1.98
   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:	0.03
   Maximum:	0.18
   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:	0.21
   Maximum:	6.22
   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:	0.08
   Maximum:	0.80
   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:	0.50
   Maximum:	28.07
   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:	0.28
   Maximum:	2.61
   Units:	Disintegrations per minute per gram
   Resolution:	0.01

   18CCT09_GrainSize.xlsx

   Microsoft Excel workbook summarizing grain-size parameters for each surface sample and centimeter depth interval from the sediment cores collected on the Point aux Chenes marshes and the surrounding estuary (USGS FAN 2018-358-FA). 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)

   18CCT09_GrainSize.csv

   Comma-separated values text files summarizing grain-size parameters for each surface sample and centimeter depth interval from the sediment cores collected on the Point aux Chenes marshes and the surrounding estuary (USGS FAN 2018-358-FA). 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)

   Entity_and_Attribute_Overview:

   The detailed attribute descriptions for the grain size workbooks are provided in the included data dictionary (18CCT09_GrainSize_DataDictionary.pdf). These metadata are not complete without this file.

   Entity_and_Attribute_Detail_Citation:

   Data Dictionary for Gradistat grain-size output, in: Ellis, A.M., Smith, C.G., Vargas, J., and Everhart, C., 2021, Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi (ver. 1.0, August 2021), https://doi.org/10.5066/P9XYDHFZ

   Entity_and_Attribute_Overview:

   The processed x-ray images of each marsh push core are provided for non-quantitative purposes only (18CCT09_Xrays.zip).

   Entity_and_Attribute_Detail_Citation:

   Core x-radiographic images (.jpg) provided in, in: Ellis, A.M., Smith, C.G., Vargas, J., and Everhart, C., 2020, Sedimentologic Data from Point aux Chenes Marsh and Estuary, Mississippi, (ver. 1.0, August 2021), https://doi.org/10.5066/P9XYDHFZ

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 Everhart
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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   aellis@usgs.gov

Why was the data set created?

Dissemination of processed sediment data from sediment surface and core samples collected from Point aux Chenes marsh and estuary, Mississippi (FAN 2018-358-FA).

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: 2018 (process 1 of 10)

   Surface grab samples were taken from estuarine sites (GB542G-GB563G) using a petite PONAR grab sampler, deployed according to manufacturer specifications. The sediment recovered in the grab sampler was inspected for an undisturbed (i.e., free of slumping, washout, scouring, cracking, and/or other disturbance features) sediment-water interface to ensure the bulk sample collected was representative of the surface and material was not lost. If the sediment was disturbed, the sediment was discarded and a new grab sample was collected and assessed. If the sediment surface was intact, the any overlying water and the mesh screens were slowly removed in accordance with the product manual, and the uppermost one centimeter of sediment was subsampled with a spoon or scoopula for sediment characterization as described in Osbourne and Delaune (2013) and for consistency with related products (Ellis and Smith, 2021; Haller et al., 2019) and as is standard and recommended for recent surficical sediment and microfossil analyses (Schonfeld et al., 2012). Water quality properties at each estuarine site were measured with a YSI Pro-DSS and values were recorded. At ten sites on the Point aux Chenes marsh, push cores (GB530M-GB541M) 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 discontinuties) to ensure the core was intact and representataive of the site. If the core appeared disturbed, it was discarded and a new core was collected and inspected. Core lengths ranged between 36 and 65 cm. 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 decomposisiton, 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 include handwritten notes visible on the scanned field logs for each site. Sample identifiers consist of the USGS project ID (18CCT09), a site-specific identifier (for example, GB542), and appended with an alphabetic identifier to differentiate the sediment collection method (S for marsh surface sample, M for marsh push core, G for estuarine grab sample, R for Russian peat auger). Estuarine site coordinates and water depth were recorded with a Garmin EchoMapPlus 63v boat GPS and depth sounder; push core locations were initially recorded at the time of collection using a Garmin GPSMAP 76S 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. 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_SiteInformation.zip

   Date: 2018 (process 2 of 10)

   DGPS Acquisition: a DGPS base station was erected on a NGS benchmark located within the Grand Bay National Estuarine Research Reserve, B166 (PID DO5987). At the 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 30 minutes per sample site, which provide more accurate horizontal and vertical control than handheld GPS units. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_SiteInformation.zip

   Date: 2018 (process 3 of 10)

   GPS Post-Processing: The final, time weighted coordinates from 18CCT09 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. 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 NAD83, Universal Transverse Mercator (UTM) Zone 16 north (16N) horizontal reference frame and the North American Vertical Datum of 1988 (NAVD88) orthometric elevation using the NGS geoid model of 2012A (GEOID12A). 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_SiteInformation.zip

   Date: 2018 (process 4 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 then exported as .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 extraction and subsampling to assess peat thickness in comparison with peat augers, presence of macrofossils which may impead sectioning, and to ensure cores are intact for the length of the core. Person who carried out this activity:
   

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

   Attn: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_XRays.zip

   Date: 2018 (process 5 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, 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 St. Petersburg Coastal and Marine Science Center

   Attn: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Date: 2018 (process 6 of 10)

   In the laboratory, marsh core samples were homogenized in the sample bag to ensure a representative subsample from the 1-cm interval, 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/weighboat, 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. 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. 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_SedimentPhysicalProperties.zip

   Date: 2018 (process 7 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 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 et al., 2011; Heiri et al., 2001; Santisteban et al., 2004). In error, marsh push core GB541M was heated to 800 °C instead of 550 °C for 6 hours, which may result in an overestimate of organic matter content due to potential degredadation of inorganic carbon at the higher temperature, which is considered to peak at 950 °C (Galle and Runnels, 1960). Following the 6 hour burn time for removal of organic carbon, The furnace 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); OM content for core GB541M may be overestimated due to the increased furnace temperature. Approximately 13 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. 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   U.S.

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_SedimentPhysicalProperties.zip

   Date: 2019 (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 et al., 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 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Date: 2019 (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 (6-8 runs per sample), and highlight 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. The individual run statistics or all sites, prior to averaging, is available upon request. Person who carried out this activity:
   

   U.S. Geological Survey

   Attn: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   (727) 502-8000 (voice)

   aellis@usgs.gov

   Data sources produced in this process:

   • 18CCT09_GrainSize.zip

   Date: 2020 (process 10 of 10)

   Dried, ground sediment from the 1-cm depth intervals of the 10 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. 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 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-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), 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:

   • 18CCT09_GammaSpectroscopy.zip

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:

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

   Other_Citation_Details: Pages 1237-1248
   

   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: Methods in Biogeochemistry of Wetlands Volume 10.

   Online Links:

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

   Other_Citation_Details: Pages 21-41
   

   Osbourne, T.Z. and DeLaune R.D., 2013, Soil and Sediment sampling of Inundated Environments: Health Physics Volume 51.

   Online Links:

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

   Other_Citation_Details: Pages 53-59
   

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

   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., 1957, Brazos River Bar: A study in the significance of grain size parameters: Journal of Sedimentary Petrology Volume 27.

   Other_Citation_Details: Pages 3-26
   

   Krumbien, W.C., 1934, Size frequency distributions of sediments: Journal of Sedimentary Petrology Volume 4, No. 2.

   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.

   Other_Citation_Details: pages 377-392
   

   Dean, W.E., 1974, 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.

   Other_Citation_Details: pages 242-248
   

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

   Other_Citation_Details: 792 pages
   

   Ellis, A.M., and Smith, C.G., 2021, Emerging dominance of Paratrochammina simplissima (Cushman and McCulloch) in the northern Gulf of Mexico following hydrologic and geomorphic changes: Estuarine, Coastal and Shelf Science Volume 255.

   Online Links:

   • https://doi.org/10.1016/j.ecss.2021.107312

   Other_Citation_Details: 15 pages
   

   Haller, C., Smith, C.G., Hallock, P., Hine, A.C., Osterman, L.E., and McCloskey, T., 2019, DISTRIBUTION OF MODERN SALT-MARSH FORAMINIFERA FROM THE EASTERN MISSISSIPPI SOUND, U.S.A.: Journal of Foraminiferal Research Volume 24.

   Online Links:

   • https://doi.org/10.2113/gsjfr.49.1.29

   Other_Citation_Details: pages 24-47
   

   Schönfeld, J., Alve, E., Geslin, E., Jorissen, F., Korsun, S., Spezzaferri, S., and Members of the FOBIMO group, 2012, The FOBIMO (FOraminiferal BIo-MOnitoring) initiative—Towards a standardised protocol for soft-bottom benthic foraminiferal monitoring studies: Marine Micropaleontology Volume 94-95.

   Online Links:

   • https://doi.org/10.1016/j.marmicro.2012.06.001

   Other_Citation_Details: pages 1-13
   

   Nittrouer, C.A., Sternberg, R.W., Carpenter, R., and Bennett, J.T., 1979, The use of Pb-210 geochronology as a sedimentological tool: application to the washington continental shelf: Marine geology Volume 31.

   Online Links:

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

   Other_Citation_Details: pages 297-316
   

   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

   Galle, O.K., and Runnels, R.T., 1960, Determination of CO2 in carbonate rocks by controlled loss on ignition: Journal of Sedimentary Petrology vol. 30.

   Online Links:

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

   Other_Citation_Details: pages 613-618
   

   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., 2004, Loss on ignition: a qualitative or quantitative method for organic matter and carbonate mineral content in sediments?: Journal of Paleolimnology vol. 32.

   Online Links:

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

   Other_Citation_Details: pages 287-299
   

   Wang, Q., Li, Y., and Wang, Y., 2011, Optimising the weight loss-on-ignition methodology to quantify organic and carbonate carbon of sediments from diverse sources: Environmental Monitoring and Assessment vol. 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., 2001, Loss on Ignition as a method for estimating organic and carbonate content in sediments: reproducibility and comparability of results: Journal of Paleolimnology vol. 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?
   The positional accuracy of the sample locations is determined by the accuracy of the raw position data recorded by the GPS antenna, in the North American Datum of 1983 (NAD83), during data collection. Differential Global Positioning System (DGPS) coordinates were obtained using post-processing software packages (National Geodetic Survey On-Line Positioning User Service, OPUS, and Novatel Waypoint Product Group GrafNav). 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 the base station: NGS Permanent Identifier [PID]DO5987, stamping 0166 B 2010 (recording site name B166) located at the boat ramp at the northern end of Bayou Heron. Base station positional error was calculated as the absolute value of the final position minus the session position value. The estimated post-processed horizontal accuracy (2-sigma) for the core locations was 0.00015 +/- 0.00007 seconds latitude and 0.00013 +/- 0.00006 seconds longitude.
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. The maximum vertical error of the base station coordinates used for post-processing the sample locations was 0.011 +/- 0.006 meters.
4. Where are the gaps in the data? What is missing?
   This data release doi:10.5066/P9XYDHFZ contains all sediment data associated with this USGS FAN and includes the geographic site location, water quality parameters, sediment physical properties, grain size statistics, and sediment radiochemistry activities for ten cores collected at ten sites on Point aux Chenes marsh and marsh surface and estuarine grab samples, collected in October, 2018.
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 (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?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:

Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. 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: Alisha M. Ellis

   Geologist

   600 4th Street South

   St. Petersburg, FL
   

   USA

   727-502-8000 (voice)

   aellis@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:

     This zip archive includes Microsoft Excel spreadsheets (.xlsx), comma-separated values text files (.csv), Portable Document Format (PDF) files, Joint Photographic Experts Group files (JPEG) and accompanying metadata for sediment data from surface samples and cores collected from the Point aux Chenes marsh and surrounding Grand Bay estuary (USGS FAN 2018-358-FA). in format Compressed (zip) archive WinZip, 7-Zip

     Network links:

     https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_SiteInformation.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_SedimentPhysicalProperties.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_GrainSize.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_GammaSpectroscopy.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_FieldLogs.zip https://coastal.er.usgs.gov/data-release/doi-P9XYDHFZ/data/18CCT09_XRays.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 2018-358-FA were created in Microsoft Excel for Mac version 16.37 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. 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: 21-Sep-2021

Metadata author:

U.S. Geological Survey

Attn: Alisha M. Ellis

Geologist

600 4th Street South

St. Petersburg, FL

USA

727-502-8000 (voice)

aellis@usgs.gov

Metadata standard:

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