Nearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware

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What does this data set describe?

Title:
Nearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware
Abstract:
Assessment of biogeochemical processes and transformations at the aquifer-estuary interface and measurement of the chemical flux from submarine groundwater discharge (SGD) zones to coastal water bodies are critical for evaluating ecosystem service, geochemical budgets, and eutrophication status. The U.S. Geological Survey and the University of Delaware measured rates of SGD and concentrations of dissolved constituents, including nitrogen species, from recirculating ultrasonic and manual seepage meters, and in nearshore groundwater, on the southern shore of Guinea Creek, an estuarine tributary of Rehoboth Bay, in Millsboro, Delaware, in June, August, and October of 2015. A novel oxygen- and light-regulated seepage meter and a standard seepage meter were deployed as an adjacent pair and sampled at 0.5- to 2-hour intervals across the majority or entirety of single tidal cycles (8 to 12 hours). SGD rate was measured within an attached collection bag (0.5- to 2-hour intervals), or with an ultrasonic flow sensor (1-second intervals). Groundwater samples were collected at multiple depths (5 to 83 centimeters) in shore-perpendicular transects extending across the nearshore subtidal SGD zone. Constituents and other parameters measured in seepage meters and groundwater included: dissolved oxygen, salinity, pH, oxidation/reduction potential, temperature, nitrate, ammonium, phosphate, dissolved organic and inorganic carbon, stable isotopic ratios of carbon species, trace elements, and alkalinity. These data can be used to evaluate biogeochemical conditions and extent of chemical transformation in the upper coastal aquifer and surface sediments and to calculate fluxes of nitrogen and other constituents carried by SGD across the aquifer-estuary interface.
Supplemental_Information:
Related primary publication:
Brooks, T.W., Kroeger, K.D., Michael, H.M., and York, J.K., 2021, Oxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer-estuary interface: Limnology and Oceanography, https://doi.org/10.1002/lno.11858.
This dataset is associated with USGS field activity 2015-056-FA. Additional information for this field activity can be acquired from the field activity landing page: https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-056-FA.
  1. How might this data set be cited?
    Brooks, T.W., Kroeger, K.D., Michael, H.A., Szymczycha, B., Eagle, M. J., and York, J.K., 20210608, Nearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware: data release DOI:10.5066/P94NBY3Z, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation:
    Brooks, T.W., Kroeger, K.D., Michael, H.A., Szymczycha, B., Eagle, M.J., and York, J.K., 2021, Nearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware: U.S. Geological Survey data release, https://doi.org/10.5066/P94NBY3Z
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.16647
    East_Bounding_Coordinate: -75.16623
    North_Bounding_Coordinate: 38.63594
    South_Bounding_Coordinate: 38.63586
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5fec8c1ed34ea5387defd59d?name=Thumbnail_Image_GuineaCreek.jpg (JPEG)
    Schematic of the sampling scheme adapted from Brooks and others (2021).
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 08-Jun-2015
    Ending_Date: 22-Oct-2015
    Currentness_Reference:
    Ground condition of when samples were collected, although the samples were not collected daily.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Tabulated comma-separated values files
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (774)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is World Geodetic System 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Sediment surface
      Depth_Resolution: 0.01
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Discrete_GeochemicalData_GuineaCreek
    Geochemical and field data collected from the recirculating oxygen-regulated and standard seepage meters (RSM and SSM), and in nearshore groundwater at Guinea Creek in June, August, and October of 2015. This csv file contains 164 data records. (Source: Producer defined.)
    SampleType
    Identifier specifying the type of water sample, either SeepageMeter_Regulated, SeepageMeter_Standard, or Groundwater. (Source: Producer defined.) Character set.
    Deployment_ID
    Identifier specifying the corresponding deployment in the format Month_SeepageMeterType_SiteID, e.g., June_RSM_Site_01. RSM represents regulated seepage meter and SSM represents standard seepage meter. Samples of type "Groundwater" do not have deployment IDs, and are therefore blank. (Source: Producer defined.) Character set.
    Sample_ID
    Unique identifier for discrete water samples. Sample_ID for samples from the recirculating seepage meters are in the format seepage meter type, site ID, time point, month, e.g. RSM1-1-Aug. Groundwater Sample_ID do not follow a consistent naming convention, but are further identified by date, time, location, and sample depth attributes. (Source: Producer defined.) Character set.
    Date_UTC
    Date in Coordinated Universal Time (UTC) at which the water sample was collected in the format mm/dd/yyyy, month/day/year. (Source: Producer defined.)
    Range of values
    Minimum:6/8/2015
    Maximum:10/22/2015
    Units:month/day/year
    DateTime_UTC
    Date and time in 24 hour Coordinated Universal Time (UTC) at which the water sample was collected in the format m/d/yyyy h:mm, month/day/year hour:minutes. Blank cells indicate time was not measured for samples of type "Groundwater" collected on 8/11/2015 and 10/19/2015 through 10/22/2015. (Source: Producer defined.)
    Range of values
    Minimum:6/8/2015 18:05
    Maximum:10/22/2015 21:30
    Units:month/day/year and time
    Latitude_WGS84_degN
    Latitude in decimal degrees north, measured using the WGS84 datum. See Notes attribute for location details (distance and direction from a specified waypoint) for limited cases when groundwater sample location was not measured by GPS and therefore does not have a latitude value. (Source: Producer defined.)
    Range of values
    Minimum:38.63586
    Maximum:38.63594
    Units:decimal degrees
    Longitude_WGS84_degW
    Longitude in decimal degrees west, measured using the WGS84 datum. A negative value indicates the western hemisphere. See Notes attribute for location details (distance and direction from a specified waypoint) for limited cases when groundwater sample location was not measured by GPS and therefore does not have a longitude value. (Source: Producer defined.)
    Range of values
    Minimum:-75.16647
    Maximum:-75.16623
    Units:decimal degrees
    GWSampleDepth_cm
    Depth of the mid-point of the well screen below the sediment surface at which the groundwater sample was collected. (Source: Producer defined.)
    Range of values
    Minimum:5
    Maximum:83
    Units:centimeters
    Temp_degC
    Temperature of the water sample, either in situ (for sample type "SeepageMeter") or once pumped above the sediment surface (for sample type "Groundwater"). Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:10.30
    Maximum:32.93
    Units:degrees Celsius
    SpCond_mSpercm
    Specific conductance. A measure of the ability of the water sample to conduct electricity at the standard temperature of 25 degrees Celsius. Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:28.25
    Maximum:43.93
    Units:millisiemens per centimeter
    Salinity_PSU
    Salinity of the water sample measured in practical salinity units (PSU, dimensionless). (Source: Producer defined.)
    Range of values
    Minimum:0.06
    Maximum:28.29
    Units:practical salinity units (dimensionless)
    DO_percentSat
    Dissolved oxygen (DO) saturation of the water sample. Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:1.00
    Maximum:183.80
    Units:percent saturation
    DO_mgperL
    Dissolved oxygen (DO) concentration of the water sample. Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:0.07
    Maximum:11.77
    Units:milligrams per liter
    pH
    Negative logarithm of hydronium ion activity [H+] of the water sample. Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:4.79
    Maximum:8.30
    Units:unitless
    ORP_mV
    Oxidation/Reduction potential (ORP) of the water sample. Not recorded for seepage meter Deployment_IDs October_SSM_Site_01 and October_SSM_Site_02, therefore cells are blank for those records. (Source: Producer defined.)
    Range of values
    Minimum:-388.10
    Maximum:330.40
    Units:millivolts
    Nitrate_umolperL
    Concentration of dissolved nitrate plus nitrite (NO3- + NO2-) of the water sample. Note that the analytical limit of detection is equal to 0.05 micromoles per liter (LOD = 0.05 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.64
    Maximum:405.24
    Units:micromoles per liter
    Ammonium_umolperL
    Dissolved ammonium (NH4+) concentration of the water sample. Note that the analytical limit of detection is equal to 0.05 micromoles per liter (LOD = 0.05 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.00
    Maximum:73.37
    Units:micromoles per liter
    Phosphate_umolperL
    Dissolved phosphate (PO43-) concentration of the water sample. Note that the analytical limit of detection is equal to 0.05 micromoles per liter (LOD = 0.05 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.03
    Maximum:2.02
    Units:micromoles per liter
    DOC_umolperL
    Dissolved organic carbon (DOC) concentration of the water sample. Note that the analytical limit of detection is equal to 10 micromoles per liter (LOD = 10 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:11.78
    Maximum:1574.17
    Units:micromoles per liter
    DOC_d13C_permil
    Delta (d) 13C of dissolved organic carbon (DOC) in the water sample, a measure of the stable isotopic ratio of 13C : 12C expressed relative to Vienna Pee Dee Belemnite (VPDB). The analytical limit of detection of d13C and DOC concentration is equal to 10 micromoles per liter DOC (LOD = 10 uM). (Source: Producer defined.)
    Range of values
    Minimum:-63.92
    Maximum:-21.32
    Units:per mil
    DIC_umolperL
    Dissolved inorganic carbon (DIC) concentration of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:956.27
    Maximum:2121.00
    Units:micromoles per liter
    DIC_d13C_permil
    Delta (d) 13C of dissolved inorganic carbon (DIC) in the water sample, a measure of the stable isotopic ratio of 13C : 12C expressed relative to Vienna Pee Dee Belemnite (VPDB). (Source: Producer defined.)
    Range of values
    Minimum:-21.25
    Maximum:-2.77
    Units:per mil
    Mn_umolperL
    Dissolved manganese (Mn) concentration of the water sample. Note that the analytical limit of detection is equal to 0.01 micromoles per liter (LOD = 0.01 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.03
    Maximum:1.81
    Units:micromoles per liter
    Fe_umolperL
    Dissolved iron (Fe) concentration of the water sample. Note that the analytical limit of detection is equal to 0.01 micromoles per liter (LOD = 0.01 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.13
    Maximum:21.84
    Units:micromoles per liter
    Cu_nmolperL
    Dissolved copper (Cu) concentration of the water sample. Note that the analytical limit of detection is equal to 0.01 nanomoles per liter (LOD = 0.01 nM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:18.55
    Maximum:245.84
    Units:nanomoles per liter
    Sr_umolperL
    Dissolved strontium (Sr) concentration of the water sample.Note that the analytical limit of detection is equal to 0.01 micromoles per liter (LOD = 0.01 uM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:1.12
    Maximum:77.42
    Units:micromoles per liter
    Ba_nmolperL
    Dissolved barium (Ba) concentration of the water sample. Note that the analytical limit of detection is equal to 0.01 nanomoles per liter (LOD = 0.01 nM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:205.70
    Maximum:3149.15
    Units:nanomoles per liter
    U_nmolperL
    Dissolved uranium (U) concentration of the water sample. Note that the analytical limit of detection is equal to 0.01 nanomoles per liter (LOD = 0.01 nM) and values below the LOD are truly an unknown value between zero and the LOD. (Source: Producer defined.)
    Range of values
    Minimum:0.29
    Maximum:11.67
    Units:nanomoles per liter
    Chloride_mmolperL
    Dissolved chloride (Cl-) concentration of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:259.01
    Maximum:378.19
    Units:millimoles per liter
    Sulfate_mmolperL
    Dissolved sulfate (SO42-) concentration of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:15.65
    Maximum:19.47
    Units:millimoles per liter
    TotalAlkalinity_ueqperL
    Total alkalinity of the water sample, a measure of the ability of the water sample to resist change in pH. (Source: Producer defined.)
    Range of values
    Minimum:240.89
    Maximum:1578.69
    Units:microequivalents per liter
    Notes
    Field notes or observations pertaining to the particular Sample_ID or Deployment_ID. Includes location details (as distance and direction from a specified waypoint) for limited cases when groundwater sample location was not measured by GPS. (Source: Producer defined.) Character set.
    WaterQualityParameters_GuineaCreek
    In situ field water quality parameters measured and internally logged with multiparameter sondes in the regulated and standard recirculating seepage meters (RSM and SSM) and in nearby estuarine surface water in June, August, and October of 2015. This csv file contains 11,427 data records. (Source: Producer defined.)
    SampleType
    Identifier specifying the type of water sample, either SeepageMeter_Regulated, SeepageMeter_Standard, or Estuary. (Source: Producer defined.) Character set.
    Deployment_ID
    Identifier specifying the corresponding deployment in the format Month_SeepageMeterType_SiteID, e.g., June_RSM_Site_01, June_SampleType_Site_01. RSM represents regulated seepage meter and SSM represents standard seepage meter. (Source: Producer defined.) Character set.
    DateTime_UTC
    Date and time in 24 hour Coordinated Universal Time (UTC) for the measurement in the format m/d/yyyy h:mm, month/day/year hour:minutes. (Source: Producer defined.)
    Range of values
    Minimum:6/10/2015 4:54
    Maximum:10/22/2015 21:48
    Units:month/day/year and time
    Latitude_WGS84_degN
    Latitude in decimal degrees north, measured using the WGS84 datum. (Source: Producer defined.)
    Range of values
    Minimum:38.63591
    Maximum:38.63593
    Units:decimal degrees
    Longitude_WGS84_degW
    Longitude in decimal degrees west, measured using the WGS84 datum. A negative value indicates the western hemisphere. (Source: Producer defined.)
    Range of values
    Minimum:-75.16640
    Maximum:-75.16630
    Units:decimal degrees
    Temp_degC
    In situ water temperature. (Source: Producer defined.)
    Range of values
    Minimum:12.67
    Maximum:33.07
    Units:degrees Celsius
    SpCond_mSpercm
    Specific conductance. A measure of the ability of the water sample to conduct electricity at the standard temperature of 25 degrees Celsius. (Source: Producer defined.)
    Range of values
    Minimum:27.32
    Maximum:45.27
    Units:millisiemens per centimeter
    Salinity_PSU
    Salinity of the water sample measured in practical salinity units (PSU, dimensionless). (Source: Producer defined.)
    Range of values
    Minimum:16.67
    Maximum:29.25
    Units:practical salinity units (dimensionless)
    DO_percentSat
    Dissolved oxygen (DO) saturation of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:0.70
    Maximum:196.20
    Units:percent saturation
    DO_mgperL
    Dissolved oxygen (DO) concentration of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:0.05
    Maximum:14.52
    Units:milligrams per liter
    pH
    Negative logarithm of hydronium ion activity [H+] of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:6.80
    Maximum:8.30
    Units:unitless
    ORP_mV
    Oxidation/Reduction potential (ORP) of the water sample. (Source: Producer defined.)
    Range of values
    Minimum:-397.30
    Maximum:329.80
    Units:millivolts
    WaterDepth_m
    Water depth measured as the vertical distance between the sediment surface and the water surface. Water depth was not measured for sample type "SeepageMeter_Regulated" or "SeepageMeter_Standard" - cells corresponding to those records are therfore blank. (Source: Producer defined.)
    Range of values
    Minimum:0.495
    Maximum:1.421
    Units:meters
    GroundwaterSeepage_Ultrasonic_GuineaCreek
    Submarine groundwater seepage rate measured from the oxygen regulated seepage meter with the ultrasonic flow sensor, internally logged at 1 second frequency, at Guinea Creek in June and October 2015. This csv file contains 119,592 data records. (Source: Producer defined.)
    Deployment_ID
    Identifier specifying the corresponding deployment in the format Month_SeepageMeterType_SiteID; either June_RSM_Site_01, October_RSM_Site_01, or October_RSM_Site_02. (Source: Producer defined.) Character set.
    DateTime_UTC
    Date and time in 24 hour Coordinated Universal Time (UTC) for the measurement in the format m/d/yyyy h:mm:ss, month/day/year hour:minutes:seconds. (Source: Producer defined.)
    Range of values
    Minimum:6/14/2015 14:00:00
    Maximum:10/22/2015 21:32
    Units:month/day/year and time
    Latitude_WGS84_degN
    Latitude in decimal degrees north, measured using the WGS84 datum. (Source: Producer defined.)
    Range of values
    Minimum:38.63591
    Maximum:38.63593
    Units:decimal degrees
    Longitude_WGS84_degW
    Longitude in decimal degrees west, measured using the WGS84 datum. A negative value indicates the western hemisphere. (Source: Producer defined.)
    Range of values
    Minimum:-75.16640
    Maximum:-75.16630
    Units:decimal degrees
    WaterVelocity_Ultrasonic_cmpersecond
    Water velocity through the flow tube on the seepage meter. Raw value as measured by the ultrasonic sensor. Positive values indicate discharge from the aquifer to the estuary and negative values indicate recharge from the estuary into the aquifer. (Source: Producer defined.)
    Range of values
    Minimum:-0.955
    Maximum:1.332
    Units:centimeters per second
    GWSeepage_Ultrasonic_Lperhour
    Ultrasonic volumetric groundwater seepage rate across the seabed, expressed in units of liters per hour. Positive values indicate discharge from the aquifer to the estuary and negative values indicate recharge from the estuary into the aquifer. (Source: Producer defined.)
    Range of values
    Minimum:-3.526
    Maximum:4.918
    Units:liters per hour
    GWSeepage_Ultrasonic_cmperday
    Ultrasonic specific groundwater seepage rate across the seabed, expressed in units of centimeters per day. Positive values indicate discharge from the aquifer to the estuary and negative values indicate recharge from the estuary into the aquifer. (Source: Producer defined.)
    Range of values
    Minimum:-18.565
    Maximum:25.894
    Units:centimeters per day
    GroundwaterSeepage_Manual_GuineaCreek
    Manual measurements of submarine groundwater seepage rate from the oxygen regulated and standard seepage meters (RSM and SSM) in June, August and October of 2015 in Guinea Creek. This csv file contains 89 data records. (Source: Producer defined.)
    Deployment_ID
    Identifier specifying the corresponding deployment in the format Month_SeepageMeterType_SiteID, e.g., June_RSM_Site_01, where RSM represents regulated seepage meter and SSM represents standard seepage meter. The exception is for Deployment_ID "June_SSM_Site_02_06092015", which has an appended date in the format ddmmyyyy. Since there were two deployments at Site_02 during June, therefore this appended date distinguishes it. (Source: Producer defined.) Character set.
    Latitude_WGS84_degN
    Latitude in decimal degrees north, measured using the WGS84 datum. (Source: Producer defined.)
    Range of values
    Minimum:38.63586
    Maximum:38.63594
    Units:decimal degrees
    Longitude_WGS84_degW
    Longitude in decimal degrees west, measured using the WGS84 datum. A negative value indicates the western hemisphere. (Source: Producer defined.)
    Range of values
    Minimum:-75.16647
    Maximum:-75.16623
    Units:decimal degrees
    DateTime_Initial_UTC
    Date and time corresponding to the start of the groundwater seepage measurement. Reported in 24 hour Coordinated niversal Time (UTC) in the format m/d/yyyy h:mm, month/day/year hour:minutes. (Source: Producer defined.)
    Range of values
    Minimum:6/8/2015 12:43
    Maximum:10/22/2015 20:41
    Units:month/day/year and time
    DateTime_Final_UTC
    Date and time corresponding to the end of the groundwater seepage measurement. Reported in 24 hour Coordinated Universal Time (UTC) in the format m/d/yyyy h:mm, month/day/year hour:minutes. (Source: Producer defined.)
    Range of values
    Minimum:6/8/2015 15:14
    Maximum:10/22/2015 21:28
    Units:month/day/year and time
    GWSeepage_Lperhour
    Volumetric groundwater seepage rate across the seabed, expressed in units of liters per hour. Positive values indicate discharge from the aquifer to the estuary and negative values indicate recharge from the estuary into the aquifer. (Source: Producer defined.)
    Range of values
    Minimum:-0.20
    Maximum:1.66
    Units:liters per hour
    GWSeepage_cmperday
    Specific groundwater seepage rate across the seabed, expressed in units of centimeters per day. Positive values indicate discharge from the aquifer to the estuary and negative values indicate recharge from the estuary into the aquifer. (Source: Producer defined.)
    Range of values
    Minimum:-1.04
    Maximum:15.50
    Units:centimeters per day
    Notes
    Field notes or observations pertaining to the particular Deployment_ID. (Source: Producer defined.) Character set.
    Entity_and_Attribute_Overview:
    The first line of each CSV file is a header line and those labels are the same as defined in the attribute section. Other than the limited number of cases when data was omitted due to reasons described in the Completeness Report, blank cells in the attached data files indicate either the attribute does not pertain to the sample or the attribute was not measured for the sample. The explanation for the presence of blank cells for this entire dataset is therefore captured in the above description, and the description provided in the Completeness Report and is not stated for individual Attribute Definitions in addition.
    Analytical limits of detection are reported in the Attribute Definition, and the Process Description, when applicable. In a limited number of cases, post-processing of laboratory geochemical data resulted in slight negative values, insignificantly different from zero as based on known analytical precision and are reported as zero (0) in this dataset. Positive values that are below the analytical limit of detection are reported as measured and are not set to an arbitrary value such as 'zero' or 'BDL'. Note that any value below the reported limit of detection is truly an unknown value between zero and the limit of detection. Additional quality assurance information, including analytical precision of individual analytes, is reported in the Process Description.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Brooks, T.W.
    • Kroeger, K.D.
    • Michael, H.A.
    • Szymczycha, B.
    • Eagle, M. J.
    • York, J.K.
  2. Who also contributed to the data set?
    We thank Daniel Torre, Chris Russoniello, Stephanie DeVries, John Pohlman, and Adrian Mann for field and/ or analytical assistance.
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Thomas W. Brooks
    Physical Scientist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2359 (voice)
    wallybrooks@usgs.gov

Why was the data set created?

The purpose of this study was to evaluate biogeochemical conditions and extent of chemical transformation in the upper coastal aquifer and surface sediments and to calculate fluxes of nitrogen and other constituents across the aquifer-estuary interface carried by SGD.

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: 22-Oct-2015 (process 1 of 11)
    Recirculating oxygen-regulated and standard seepage meters:
    Two different designs of recirculating seepage meters were used to measure SGD and fluxes of dissolved constituents from benthic sediments under contrasting biogeochemical conditions at the Guinea Creek field site in June, August, and October of 2015. Details pertaining to seepage meter design and operation are described in this Process Description, and in below Process Descriptions. The below detail, and additional detail is available in Brooks and others (2021).
    The oxygen- and light-regulated seepage meter (RSM) consists of a stainless-steel cylindrical base with a detachable transparent 0.5 centimeter thick polycarbonate lid. Four “stops” fabricated from sections of stainless-steel angle stock are bolted to the inside of the seepage cylinder and ensure deployment at a consistent depth into the sediment each time. A 3.5 millimeter wall thickness, 9.5 millimeter inner diameter titanium pipe is attached to the side of the seepage cylinder to allow the quantification of groundwater seepage rate via an ultrasonic or manual approach. The material and geometry of the flow tube were selected for optimal precision in flow measurements by the ultrasonic sensor (FLEXIM F7407; FLEXIM Corp., Edgewood, NY, USA) based on manufacturer recommendations. Water is continuously recirculated through a recirculating flow system with a 10 liter per minute capacity 12-volt diaphragm pump, sufficient to provide thorough mixing, but not resuspend or disturb the sediment. Results of a tracer injection test on mix time indicated the water contained in the seepage meter headspace and circulation system is 95 percent mixed within 1.3 minutes of injection of the tracer. The flow system includes a length of gas permeable silicone tubing (9.5 mm inner diameter, 1.6 mm wall thickness) to allow the dissolved gas concentrations within the seepage meter, including oxygen, to achieve equilibrium with the surrounding water body. The length of the gas permeable tubing was 91 meters for June and August, and 60 meters for October. The silicone tubing was arranged in a loose coil and placed in a protective cradle fabricated from plastic lattice fencing, foam floats, and a concrete anchor to keep the tubing situated below the water surface but above the bay floor. The flow system includes an inline multi-parameter sonde in a flow through cell, and a syringe port for collection of discrete water samples for analysis of a suite of dissolved constituents, both of which are contained on a nearby above-water sampling platform. The internal volume of the RSM headspace including the recirculating flow system once deployed into the sediment was 77.9 liters (June and August deployments) and 75.8 liters (October deployments). The area of bay floor occupied by the seepage cylinder is 0.456 square meters.
    The standard seepage meter (SSM) was constructed to test the hypothesis that isolating the enclosed water column from oxygen renewal and photosynthetically active radiation would result in artifacts in redox conditions and chemical flux. The SSM is constructed from the top portion of a 208 liter steel drum (Lee, 1977) and is operated in standard mode (for measurement of seepage rate alone) or in recirculating mode (for seepage rate and chemical flux). In recirculating mode, it employs a circulation system, discrete sampling port, and an inline multiparameter sonde as described above for the RSM. However, unlike the RSM, the design does not include gas-permeable tubing for oxygen regulation or a transparent lid for transmission of photosynthetically active radiation. Groundwater seepage rate is measured via a manual approach through a 9.5 millimeter inner diameter port located on the lid of the seepage meter. The SSM covers a surface area of 0.26 square meters, has a combined headspace and circulation system volume of 21.1 liters, and was operated with a 4 liter per minute capacity 12-volt diaphragm pump. A mixing test of the SSM yielded inconclusive results, however, the estimated turnover time of water within the SSM and flow system, based on volume and circulation rate, is 5.3 minutes, less than that of the RSM (7.8 minutes). Therefore, we anticipate the actual mix time of the SSM to be comparable, or perhaps slightly faster than the RSM.
    The contact person listed for this process description is listed below and is the same for all subsequent process descriptions. This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    References cited:
    Brooks, T.W., Kroeger, K.D., Michael, H.M., and York, J.K., 2021, Oxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer-estuary interface: Limnology and Oceanography, https://doi.org/10.1002/lno.11858. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Thomas W. Brooks
    Physical Scientist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2359 (voice)
    wallybrooks@usgs.gov
    Date: 22-Oct-2015 (process 2 of 11)
    Groundwater seepage rate:
    Rate of groundwater seepage across seabed was measured from the seepage meters either with the ultrasonic sensor at 1 second frequency (June and October RSM deployments) or manually within an attached collection bag (all other deployments). The ultrasonic and manual flow measurement approaches were adapted from Paulsen and others, (2001), and Russoniello and others (2013), respectively. For measurements made on 06/08/2015 and 06/09/2015 (see GroundwaterSeepage_Manual_GuineaCreek.csv), the SSM in standard (non-recirculating) mode was used to measure groundwater seepage rate alone. In all other cases, the RSM and the SSM were deployed as an adjacent pair, separated by 1 meter or less in a shoreline parallel orientation and sampled across 4 to 24 hour timeseries events (hereafter “paired timeseries”) for groundwater seepage rate, and dissolved constituents and other parameters. In either case, the procedures for deploying the seepage cylinders into the sediment, and for measuring groundwater seepage rate was the same. First, the seepage meters were deployed into the sediment in the nearshore subtidal zone at the Guinea Creek study site. Deployment location was measured with a Garmin GPSMAP 76CX to an accuracy of 2 meters or less. Water depth was observed at each site location for each deployment and was always between 0.3 and 1.5 meters. Unless otherwise stated (see Notes Attribute in GroundwaterSeepage_Manual_GuineaCreek.csv), following installation into the sediment, 45 minutes or longer was allowed to elapse before measuring groundwater seepage rate. Positive values for groundwater seepage indicate upward discharge of groundwater from the aquifer to the estuary (hereafter “discharge”), and negative values indicate downward recharge of estuarine surface water into the aquifer (hereafter “recharge”). Groundwater seepage is reported in this dataset in units of volumetric seepage (volume per time, e.g. liters per hour), and as specific seepage (length per time, e.g. centimeters per day).
    For manual measurements, thin-walled plastic collection bags (40 liter capacity) were pre-filled with ~2 L of bay water, to allow measurement of both groundwater discharge and recharge, and to overcome bag resistance to flow (Rosenberry and others, 2008). The pre-filled bags were weighed to the nearest 0.05 kg with a digital scale before and after deployment, and initial and final mass measurements were converted to volumes based on calculated density (Fofonoff and Millard, 1983) given additional measured values of temperature and salinity. Volumetric seepage rate was calculated as the change in volume divided by the change in time. Specific seepage rate was calculated as the volumetric seepage rate divided by the area of bay floor occupied by the seepage meter. Deployment durations of the collection bags typically ranged from 0.5 to 2.5 hours, and in one case 15 hours, when a single measurement took place overnight (6/14/2015 paired timeseries). For manual measurements of seepage rate in this dataset we report the initial DateTime and the final DateTime. Therefore, reported seepage rate represents the average seepage rate across that time interval.
    Ultrasonic flow in the RSM was measured at one second frequency with the FLEXIM F7407 sensor. Prior to deployment, the ultrasonic transducers were externally mounted onto the titanium flow tube following manufacturer recommended spacing and orientation, and the transducer/ tube assembly was encased in a water-tight rigid clear polyvinylchloride enclosure. A lead weight was secured to the exterior of the enclosure to keep the flow tube at a level and stable position resting on the bay floor. Water velocity through the flow tube (length per time, e.g. centimeters per second) was measured at one second frequency and internally logged by the sensor which was located on a nearby above-water sampling platform. The sensor was powered by two 12-volt deep cycle batteries linked in parallel. The sensor display allowed real-time monitoring of groundwater flows during measurement. Flow measurements made during times when field personnel had to inspect the flow tube for potential obstructions to flow (e.g. fish or other debris), and during discrete water sample collection (typically 5 minutes or less), are erroneous and therefore are not reported. Volumetric groundwater seepage rate was calculated as the product of the measured velocity and the inner cross-sectional area of the flow tube. Specific seepage rate was calculated by dividing the volumetric seepage rate by the area of bay floor occupied by the seepage meter. Laboratory and field measurements of instrument performance of the ultrasonic sensor are described in Brooks and others (2021). Results indicated both excellent precision (1 sigma = 0.07 centimeters per day, n = 1,200), and excellent agreement to manually measured flows (r2 = 1.00, p < 0.001, df = 19).
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    References cited:
    Fofonoff, N.P., and Millard, R.C., 1983, Algorithms for computation of fundamental properties of seawater: UNESCO Technical Papers is Marine Science. No. 44. 53 pp.
    Paulsen, R.J., Smith, C.F., O'Rourke, D., and Wong, T.F., 2001, Development and evaluation of an ultrasonic ground water seepage meter: Groundwater, 39, p. 904-911, https://doi.org/10.1111/j.1745-6584.2001.tb02478.x.
    Rosenberry, D.O., LaBaugh, J.W., and Hunt, R.J., 2008, Use of monitoring wells, portable piezometers, and seepage meters to quantify flow between surface water and ground water, p. 39-70. In D.O. Rosenberry and J.W. LaBaugh [Eds.], Field Techniques for estimating water fluxes between surface water and ground water: U.S. Geological Survey Techniques and Methods 4-D2.
    Russoniello, C.J., Fernandez, C., Bratton, J.F., Banaszak, J.F., Krantz, D.E., Andres, A.S., Konikow, L.F., and Michael, H.A., 2013, Geologic effects on groundwater salinity and discharge into an estuary: Journal of Hydrology, 498 p. 1-12, https://doi.org/10.1016/j.jhydrol.2013.05.049.
    Date: 22-Oct-2015 (process 3 of 11)
    Sampling of seepage meters for dissolved constituents during paired timeseries events:
    After the seepage cylinders were installed into the sediment, the seepage meters were flushed with bay water in an open loop configuration to ensure that chemical conditions (e.g. salinity, dissolved oxygen) closely approximated conditions in nearby estuarine bottom water prior to beginning paired timeseries measurement of dissolved constituents and other parameters. In the case of the RSM, the lid was left detached during this period, while the SSM relied on continuous flushing with the circulation pump. At the end of the equilibration period, the return tube was attached to the intake on the lid of each seepage meter, forming a closed loop.
    Discrete water samples were collected through the syringe port located on the recirculating flow systems once the seepage meters were in closed loop mode (t = 0), and at regular intervals (0.5 to 1.5 hours) throughout the timeseries events. Paired timeseries typically ranged from 4 to 12 hours in duration (see DateTime_UTC Attribute). Samples were collected into acid-cleaned, sample-rinsed, 60 milliliter All-Plastic syringes and subsampled in the field into individual vials for analysis of a suite of dissolved constituents. Subsampling into separate vials, method of preservation, and analysis of the individual constituents is described in separate process steps below. The date and time in coordinated universal time (UTC) corresponding the midpoint of the syringe sample set was recorded for t=0 and all subsequent intervals (see Discrete_GeochemicalData_GuineaCreek.csv). Sampling duration at each timepoint was approximately 4 minutes. The total volume of water removed for each set of syringe samples, including that used for rinsing, was noted during sampling and recorded (typically 220 milliliters).
    Notes on 6/14/2015 paired timeseries:
    For the 6/14/2015 paired timeseries, the RSM and SSM were left to continue measuring groundwater seepage and field water quality parameters overnight, and a final set of syringe samples were collected the following morning (RSM1-15-June and SSM1-15-June, see Discrete_GeochemicalData_GuineaCreek.csv). Upon arrival to the field site on 6/15/2015, it was discovered that the water recirculation in the SSM had stopped at some point the previous night due to a failed pump. It was later determined by evaluating continuous water quality sensor data in the SSM (see below Process Description) that this flow interruption caused by the failed pump occurred on 06/15/2015 at approximately 2:35 UTC. The pump was replaced, and circulation was restored to the SSM, and real-time readings of field water quality parameters in the SSM (see below Process Description) were allowed to stabilize, indicating complete mixing, prior to collecting the final sample set (SSM1-15-June).
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Date: 22-Oct-2015 (process 4 of 11)
    Field water quality parameters in recirculating seepage meters and in estuarine surface water:
    Water quality parameters (temperature, specific conductance, salinity, dissolved oxygen, pH, and oxidation-reduction potential) were measured in the recirculating seepage meters with calibrated YSI 600XLM multi-parameter sondes (YSI Inc., Yellow Springs, OH, USA) in water-tight YSI 696 Flow Cells located on a nearby above-water sampling platform. During the paired timeseries, parameters were measured and internally logged at 1-minute frequency. Deployment duration ranged from 4 to 24 hours. Conditions inside the flow through cells were monitored visually throughout the timeseries, and measurements were monitored in real time with a YSI 650 MDS Display. There were a few cases in which gas bubbles collected on the oxygen sensor in the RSM, most notably during periods of high oxygen saturation (200 percent or greater at times) in the RSM. The bubbles were removed by tapping the flow cell, and oxygen data corresponding to these time periods were later eliminated from the dataset (see attributes DO_percentSat and DO_mgperL in WaterQualityParameters_GuineaCreek.csv). Also note that the full suite of parameters measured from 2:33 to 13:03 Coordinated Universal Time (UTC) on 6/15/2015 in the SSM (deployment ID: June_SSM_Site_01) are not reported due to a failed pump and an interruption in water recirculation during that time (see above Process Description). The suite of parameters corresponding to the midpoint of discrete syringe sample sets (see above Process Description) for the SSM and RSM time series were extracted and are reported in Discrete_GeochemicalData_GuineaCreek.csv. Data were measured and reported in the above manner for all recirculating seepage meter deployments except for 10/20/2015 October_SSM_Site_01 and 10/22/2015 October_SSM_Site_02. For those deployments, salinity alone was measured on discrete bottle samples using a calibrated YSI 30 (see https://www.ysi.com/pro30 for instrument specifications and precision) and is reported in Discrete_GeochemicalData_GuineaCreek.csv. One-minute logged data for all other deployments are reported in WaterQualityParameters_GuineaCreek.csv.
    A calibrated YSI 600XLM-V2 sonde was deployed at a height of 10 centimeters above the bay floor adjacent to the seepage meters to measure and internally log water depth, temperature, specific conductance, salinity, optical dissolved oxygen, pH, and ORP in the estuary at 3 minute frequency (June) or 2 minute frequency (all other deployments). The sensor was deployed onto a weighted crate with the sonde and sensors oriented horizontally, parallel with the bay floor. We report only the depth relative to the bay floor, which was calculated as the raw measured water depth minus the vertical distance between the bay floor and the pressure (depth) sensor. Deployment duration ranged from 1 to 6 days.
    For all sondes, dissolved oxygen was calibrated the day of deployment, and all other parameters were calibrated the day prior to deployment following manufacturer specifications. In the case of the 600XLM sondes used in the recirculating seepage meters, the electrodes on the polarographic dissolved oxygen sensors were reconditioned according to manufacturer specifications the day of, or the day prior to deployment. Flow rate provided by the circulation pumps were within the acceptable range for polarographic dissolved oxygen measurement in the flow cells. In addition to the internal calibrations, the three sondes were simultaneously deployed in the field, both immediately before deployment, and upon retrieval, in a 5-gallon bucket of site bay water using a method adapted from Wagner and others (2006) to test for fouling and drift. A submersible 10 liter per minute capacity diaphragm pump was placed into the bucket to continuously circulate the water, and parameters were logged for 10 minutes or longer. The June and August post comparison results indicated ORP measured in the estuary (June_Estuary_Site_01 and August_Estuary_Site_01) were not within the acceptable range of accuracy and precision, likely due to prolonged exposure to reduced material. ORP data from those deployments are therefore not reported in this dataset. All other results were within the acceptable range of accuracy and precision. Instrument specifications including precision of the above listed parameters measured with the 600XLM and 600XLM-V2 sondes can be found at: https://www.ysi.com/File%20Library/Documents/Manuals/069300-YSI-6-Series-Manual-RevJ.pdf.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Reference cited:
    Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51 p.
    Date: 22-Oct-2015 (process 5 of 11)
    Groundwater sampling:
    Groundwater samples were collected at multiple depths (5 to 83 centimeters below sediment surface) at the Guinea Creek study site. Samples were collected as individual sample points, or at multiple depths in vertical profiles adjacent to the seepage meter deployments or at locations shoreward. All sample points are contained in a relatively small area in the nearshore, shallow (0.3 to 1.4 meter water depth), subtidal zone (see Bounding_Coordinates in Spatial_Domain section). Location was measured with a handheld Garmin GPSMAP 76Cx using the WGS84 datum to an accuracy of 3 meters or less in most cases. In the limited number of cases when location was not measured by GPS, it was measured as distance shoreward from either site 1 or site 2 with a meter tape to an accuracy of 0.5 meters (see Latitude, Longitude, and Notes Attributes in Discrete_GeochemicalData_GuineaCreek.csv). In many cases porewater sample collections were concurrent with paired seepage meter timeseries.
    Samples were collected with 0.6 cm outer diameter, 4 cm long screened interval stainless steel push-point sampling devices (https://www.mheproducts.com/). Samples were either collected into acid-cleaned 60 mL syringes through Tygon tubing or with a peristaltic pump through a short length of Cole-Parmer C-Flex silicone pump tubing. Sampling depth is reported as the depth of the midpoint of the well screen below the sediment surface. Field water quality parameters (temperature, specific conductance, salinity, dissolved oxygen, pH, oxidation/reduction potential) were measured with a calibrated YSI ProPlus multiparameter sonde in a flow-through cell. Field parameters were recorded once dissolved oxygen readings stabilized. Details of instrument specifications including precision of individual parameters can be found at: https://www.ysi.com/proplus. Porewater was then subsampled into individual vials in the field for geochemical analysis of a suite of dissolved constituents. The specifics of sample collection, preservation and analysis of the individual analytes are described below in subsequent process steps.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Date: 22-Oct-2015 (process 6 of 11)
    Nutrients:
    Samples for analysis of nutrients nitrate, ammonium, and phosphate were filtered through sample-rinsed 0.45 micron pore size polyethersulfone filters into acid-cleaned polyethylene vials, kept on ice in the field, and then stored frozen until analysis.
    Nitrate, ammonium, and phosphate were measured on a Seal AA3 autoanalyzer at the University of Delaware, in Lewes, DE using standard colorimetric techniques according to APHA (2005), method 4500-NO3-F, method 4500-NH3-G, and method 4500-P-F. Nitrate (NO3-) and nitrite (NO2-) were not quantified separately and their sum is referred to as nitrate (NO3-) in this report. Analytical limits of detection are 0.1 micromoles per liter (uM) for nitrate and ammonium and 0.05 uM for phosphate. for Coefficient of variation is 5% or less.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Reference cited:
    APHA, 2005, Standard methods for the examination of water and waste water, 21st edn., American Public Health Association, Washington, DC, https://doi.org/10.2105/SMWW.2882.001.
    Date: 22-Oct-2015 (process 7 of 11)
    Concentrations and stable isotopic ratios of dissolved organic carbon:
    Samples for dissolved organic carbon (DOC) concentration, and delta 13C of DOC (d13C-DOC) were filtered through sample-rinsed 0.45 micron pore size polyethersulfone filters into combusted borosilicate glass vials with acid-cleaned Teflon-lined septa caps. Vials were pretreated with 20 percent hydrochloric acid (12 microliters per milliliter of sample) to decrease the pH of the sample to 2 or less, and samples were stored at 4 degrees Celsius until analysis. Samples were analyzed for DOC on an O.I. Analytical Aurora 1030C auto-analyzer by high temperature catalytic oxidation and nondispersive infrared detection (HTCO-NDIR). Concentrations are reported relative to potassium hydrogen phthalate (KHP) calibration standard.
    Isotopic ratio of 13C:12C was measured using a Thermo-Finnigan DELTAplus XL Isotope Ratio Mass Spectrometer interfaced to the Aurora 1030C following the method of Lalonde and others (2014). Stable carbon isotope ratios are reported in standard delta (d) notation relative to Vienna Pee Dee Belemnite (VPDB). Quality assurance included replicate analysis of natural reference materials, field samples and calibration standards. Analytical uncertainties in concentration and d13C were determined based on replicate measurement of field samples. Coefficient of variation in DOC concentration and d13C were 5 percent or less, and 2 percent or less, respectively. Analytical limit of detection for DOC concentration and d13C was determined as three times the standard deviation of the analytical blank, or LOD = 10 micromoles per liter (uM).
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Reference cited:
    Lalonde, K., Middlestead, P. and Gelinas, Y., 2014, Automation of 13C/12C ratio measurement for freshwater and seawater DOC using high temperature combustion: Limnology and Oceanography: Methods, 12(12), pp. 816-829, https://doi.org/10.4319/lom.2014.12.816.
    Date: 22-Oct-2015 (process 8 of 11)
    Concentrations and stable isotopic ratios of dissolved inorganic carbon:
    Samples for DIC and delta 13C of DIC (d13C-DIC) were collected unfiltered and submitted to the University of California Stable Isotope Facility in Davis, CA (UC Davis SIF) for analysis. Samples were collected into pre-combusted borosilicate glass vials with Teflon-lined butyl rubber septa screw caps. Vials were filled from the bottom, overflowed with >3 void volumes, capped immediately without headspace, and stored at 4 degrees C until analysis.
    Samples were analyzed on a GasBench II system interfaced to a Delta V Plus isotope ratio mass spectrometer at the UC Davis SIF (https://stableisotopefacility.ucdavis.edu/dictracegas.html). Stable isotopic ratios are reported in standard delta notation relative to Vienna Pee Dee Belemnite (VPDB). Quality assurance included replicate analysis of natural reference materials and field samples. Reported long-term standard deviation in d13C and Limit of Quantification in DIC as CO2 are 150 nanomoles, and 0.1 per mil. Note that d13C-DIC data measured in the regulated seepage meter are qualitative, since the gas-permeable tubing of the regulated seepage meter is expected to exchange carbon dioxide, a component of DIC, with ambient estuarine water. This process took place over a range of time from 2012 to 2016. The process date below represents the most recent date.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Date: 22-Oct-2015 (process 9 of 11)
    Trace elements in porewater and surface water:
    Samples for trace elements analysis were filtered through a sample-rinsed 0.45 micron pore size polyethersulfone filters into acid cleaned polyethylene vials, spiked with 8 normal (N) Optima nitric acid to a pH of less than 2, and stored at room temperature until analysis.
    Samples were diluted 20-fold with 5% Optima nitric acid and analyzed on a Thermo Fisher iCAP Qc at the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, MA for manganese (Mn), iron (Fe), copper (Cu), strontium (Sr), barium (Ba), and uranium (U). Count rates were normalized to an internal indium (In) standard to account for drift and matrix interference of the solution. Water sample density was calculated based on field salinity and a typical lab temperature of 25 degrees Celsius following the method of Fofonoff and Millard (1983). Molar concentration was calculated as the product of lab-measured molal concentration and density. Quality assurance included replicate analysis of natural reference materials and field samples. Detection limits were determined as 3 times the standard deviation of the analytical blank. LOD = 0.01 uM for Mn, Fe, and Sr; and 0.01 nM for Cu, Ba, and U. Coefficient of variation = 1, 12, 11, 5, 0.3, and 7 percent for Mn, Fe, Cu, Sr, Ba, and U, respectively. Dissolved Fe data from the SSM is not reported due to risk of potential contamination from the seepage meter.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Reference cited:
    Fofonoff, N.P., and Millard, R.C., 1983, Algorithms for computation of fundamental properties of seawater: UNESCO Technical Papers is Marine Science. No. 44. 53 pp.
    Date: 22-Oct-2015 (process 10 of 11)
    Total alkalinity in porewater and surface water:
    Samples for total alkalinity were collected into acid-cleaned 60 mL HDPE plastic syringes with a two-way stopcock unfiltered without headspace and stored at 4 degrees Celsius until analysis. Samples were analyzed on a Hiranuma Sangyo Aquacounter COM-300A Automatic Titrator following standard protocols within 7 days of collection. Quality assurance included replicate analysis of natural reference materials and field samples. Results were within the acceptable range of precision and accuracy. Coefficient of variation = 2 percent.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
    Date: 22-Oct-2015 (process 11 of 11)
    Chloride and sulfate:
    Samples for chloride (Cl-) and sulfate (SO42-) were filtered through sample-rinsed 0.45 micron pore size polyethersulfone filters into acid-cleaned polyethylene vials, stored on ice in the field, and then stored frozen until analysis. Samples were analyzed on a Metrohm 850 Ion Chromatograph following standard protocols. Quality assurance included replicate analysis of field samples and calibration standards. Coefficient of variation = 1 percent for chloride and sulfate.
    This process took place over a range of time in 2015. The Process Date below represents the most recent date.
  3. What similar or related data should the user be aware of?
    Brooks, T.W., Kroeger, K.D., York, J.K., and Michael, H.A., 2021, Oxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer-estuary interface: Limnology and Oceanography LNO11858, Association for the Sciences of Limnology and Oceanography, Waco, TX.

    Online Links:

    Torre, D.M., Coyne, K.J., Kroeger, K.D., and York, J.K., 2019, Phytoplankton community structure response to groundwater-borne nutrients in the Inland Bays, Delaware, USA: Marine Ecology Progress Series Volume 624, Inter-Research, Olendorf, Germany.

    Online Links:

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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Location was measured with a handheld Garmin GPSMAP 76Cx using the WGS84 datum to an accuracy of 3 meters or less. Horizontal distance between groundwater profiles along the shore-perpendicular transect was measured with a meter tape to an accuracy of 0.5 meters.
  3. How accurate are the heights or depths?
    Vertical position (depth of the mid-point of the well screen below sediment surface) was measured by subtracting the exposed length of the push-point sampling device from the total length to an accuracy of 2 centimeters or less.
  4. Where are the gaps in the data? What is missing?
    Blank cells:
    In this dataset, blank cells are intentionally left blank and are not reported as an arbitrary integer or character set. The explanation for blank cells for a given attribute is stated in the corresponding attribute definition, unless otherwise stated below.
    Water recirculation in the SSM was interrupted in the recirculating standard seepage meter (SSM) on 06/15/2015 at approximately 2:35 UTC due to a failed pump. The pump was replaced and flow restored at approximately 12:55 UTC. Field water quality parameters (temperature, salinity, specific conductance, pH, dissolved oxygen, oxidation/reduction potential) measured during the time of the interruption in flow are not reported (see WaterQualityParameters_GuineaCreek.csv, deployment ID: June_SSM_Site_01). The June and August post-deployment water quality sonde check indicated oxidation/reduction potential (ORP) measured in the estuary during Deployment_IDs June_Estuary_Site_01 and August_Estuary_Site_01 were not within the acceptable range of accuracy and precision, likely due to prolonged exposure to reduced material. ORP data from those deployments are therefore not reported in this dataset. In a limited number of cases gas bubbles would collect on the oxygen sensor in the recirculating regulated seepage meter (RSM), most notably during periods of high oxygen saturation (200 percent or greater) in the RSM. The bubbles were removed by tapping the flow cell to prevent interference with measurements, and oxygen data corresponding to these time periods were later eliminated from the dataset (see attributes DO_percentSat and DO_mgperL in WaterQualityParameters_GuineaCreek.csv).
    The primary research objectives were focused primarily on inorganic nitrogen species cycling and fluxes, therefore certain analytes among the full suite of dissolved constituents were not always collected and/ or analyzed. Dissolved Fe was not analyzed on samples of type SeepageMeter_Standard due to the risk of potential contamination from the seepage meter.
    Other unreported data:
    Ultrasonic groundwater seepage measurements made during times when field personnel had to inspect the flow tube for potential obstructions to flow (e.g. fish or other debris), and during discrete water sample collections (typically 5 minutes or less), are erroneous and therefore are not reported.
  5. How consistent are the relationships among the observations, including topology?
    Analytical limits of detection are reported in the Attribute Definition, and the Process Description, when applicable. In a limited number of cases, post-processing of laboratory geochemical data resulted in slight negative values, insignificantly different from zero as based on known analytical precision and are reported as zero (0) in this dataset. Positive values that are below the analytical limit of detection are reported as measured and are not set to an arbitrary value such as 'zero' or 'BDL'. Note that any value below the reported limit of detection is truly an unknown value between zero and the limit of detection. Additional quality assurance information, including analytical precision of individual analytes, is reported in the Process Description.
    Field sampling, laboratory analyses, and subsequent handling and processing of data followed strict protocols and were consistent for each Process Step outlined below.
    In order to avoid the use of special characters, no subscripts, superscripts, are used in the metadata. e.g.: NO3- is actually NO subscript 3 superscript - and represents nitrate.

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 None.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains the following files: Discrete_GeochemicalData_GuineaCreek.csv (geochemical and field data collected from the recirculating seepage meters (RSM and SSM), and nearshore groundwater in a comma-separated text file); WaterQualityParameters_GuineaCreek.csv (water quality parameters measured and internally logged with multiparameter sondes in the RSM, SSM, and in nearby estuarine surface water in a comma-separated text file); GroundwaterSeepage_Ultrasonic_GuineaCreek.csv (ultrasonic groundwater seepage rate measured from the RSM in a comma-separated text file); GroundwaterSeepage_Manual_GuineaCreek.csv (manual measurements of groundwater seepage rate RSM and SSM in a comma-separated text file); DataDictionary_GuineaCreek.csv (comma-separated text file describing the contents and structure of the data files, effectively the entity and attribute details in another format); Thumbnail_Image_GuineaCreek.jpg (browse graphic); and FGDC CSDGM metadata in XML format.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These data are available in CSV format. The user must have software capable of reading this data format.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Thomas W. Brooks
Physical Scientist
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2359 (voice)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P94NBY3Z/Metadata_GuineaCreek.faq.html>
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