OFR 97-492: Washington Quadrangle NURE HSSR Study

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National Geochemical Database—Reformatted Data from the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) Program

By Steven M. Smith
Version 1.40 (2006)

Brief History and Description of Data

[See History of NURE HSSR Program for a summary of the entire program.]

Virginia
Subcontractors for the Savannah River Laboratory (SRL) collected at least 5,667 stream-sediment, 2,598 surface-water, and 4,834 ground-water samples within 96 counties from Virginia as part of the NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program. The sediment samples were collected during July - October 1976; August - September 1977; and April - November 1978, and water samples were collected during December 1976 - September 1977; April - October 1978; and June - August 1979. Sample coverage included portions of the Baltimore, Bluefield, Charlottesville, Chincoteague, Cumberland, Currituck Sound, Greensboro, Jenkins, Johnson City, Norfolk, Richmond, Roanoke, Salisbury, Washington, and Winston-Salem 1:250,000-scale quadrangles. (A total of 443 stream-sediment, 160 surface-water, and 371 ground-water samples were collected within the Washington quadrangle.) These samples were sent to SRL for analysis of uranium and additional elements (16 in sediments and 9 in waters). SRL was able to analyze 5,522 sediments and 7,416 waters from Virginia; this includes 441 sediment and 531 water samples from the Washington quadrangle. The analytical and site location data for all Virginia samples were released in the Delaware, Maryland, Virginia, and West Virginia Data Report [GJBX-103(82)].

SRL sent 2,719 sediment samples from Virginia to an unnamed contract laboratory for "Supplemental Analyses." Supplemental analytical determinations for up to 23 elements were reported for 2,711 of these samples in the Delaware, Maryland, Virginia, and West Virginia Data Report [GJBX-103(82)]. The digital data file accompanying this report includes Supplemental Analyses for 26 Virginia sediment samples within the Washington quadrangle.

Maryland
Subcontractors for the Savannah River Laboratory (SRL) collected at least 1,322 stream-sediment, 837 surface-water, and 1,188 ground-water samples within 23 counties from Maryland as part of the NURE Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program. The sediment samples were collected during May - August 1978, and water samples were collected during May - June 1977; December 1977; and July - October 1978. Sample coverage included portions of the Baltimore, Chincoteague, Cumberland, Salisbury, Washington, and Wilmington 1:250,000-scale quadrangles. (A total of 298 stream-sediment, 87 surface-water, and 318 ground-water samples were collected within the Washington quadrangle.) These samples were sent to SRL for analysis of uranium and additional elements (16 in sediments and 9 in waters). SRL was able to analyze 1,286 sediments and 2,023 waters from Maryland; this includes 294 sediment and 405 water samples from the Washington quadrangle. The analytical and site location data for all Maryland samples were released in the Delaware, Maryland, Virginia, and West Virginia Data Report [GJBX-103(82)].

SRL: Washington Quadrangle
SRL released a separate quadrangle report for the Washington NTMS quadrangle, which includes data for 729 stream-sediment and 681 ground-water samples. SRL released the analytical data as the Washington Quadrangle GJBX-284(81) Abbreviated Data Report. Although these data are given on microfiche that accompanies the report, no digital data files were found for this reformatting effort. A cursory comparison of the [GJBX-284(81)] data suggests that there are some differences between this set of HSSR data and that found for corresponding samples in the Virginia and Maryland State reports. One minor difference is that analytical data values found in the digital state files are slightly different from the hard copy tables. These variations are apparently due only to differences in rounding versus truncation of reported values or to differences in the number of recorded significant digits.

Gold Analyses
Data for gold analyses of sediments by SRL neutron activation were released in the GJBX-135(82) summary report. The introduction of that report states:

"This report contains previously unreported neutron-activation analyses of gold in sediment samples determined at SRL. These data were not included in the standard SRL NURE data reports because the gold spectrum was not measured in the original analytical procedure and the report format was designed without the gold analyses being included. Gold analyses became available as the analytical procedure was refined, but the report format was not modified to incorporate these data."

Only those sediment samples that had detectable concentrations of gold by neutron activation analysis were given in the GJBX-135(82) report. Sediment samples with concentrations below detection limits were not reported and can only be ascertained by identifying which samples were actually analyzed by neutron activation at SRL.

Summary Tables
Because of the various laboratories and analytical methods used, some SRL samples may have been analyzed once, twice, or not at all. The following table summarizes the analysis of Washington quadrangle samples.

Combination of laboratories that analyzed samples for the Washington quadrangle.
Laboratory Analysis Sediments Waters
Only SRL 709 936
Both SRL and Supplemental Labs 26 0
None 6 0
Total Samples 741 936
Total Data Records 741 936

The following is a list of all sample types collected and reported for NURE studies in the Washington quadrangle.

Summary of Washington quadrangle sample types.
Sediment Sample Type Number of Samples Water Sample Type Number of Samples
Wet Streams 741 Streams 247
    Wells 666
    Springs 23
Total Sediments 741 Total Waters 936

These Washington quadrangle samples were analyzed by one or more of the following methods:

Sediment Samples

Water Samples



Discussion of the Reformatting Process for Washington Quadrangle

Sediment Records
The Washington quadrangle sediment data consist of reformatted records from the Maryland and Virginia portions of the Delaware, Maryland, Virginia, and West Virginia [GJBX-103(82)] Data Report. The following problems were found and addressed during the comparison and reformatting stages for the Washington quadrangle sediment data:

  1. During reformatting, contamination codes for "residential" and "recreation" were found to be missing from each State's CONTAMC field. The presence of one of these two codes was indicated only by a "." (period). The missing codes were assigned a value of "unknown" in the CONTAMC field within the final sediment data file.
  2. An analysis of latitude-longitude site coordinates identified several stream-sediment samples that were missing coordinates, did not plot within expected state, county, or map boundaries, or had differing coordinates in corresponding records. To correct or confirm sample coordinates, the original field collection maps for Prince Georges County, Maryland were obtained and re-digitized. The newly re-digitized coordinates were added to the database and the coordinates from the original file(s) were recorded in the COORDPRB comment field. When the newly re-digitized coordinates were not significantly different, that confirmation of the site location was also noted in the COORDPRB comment field.
  3. After re-digitizing, seven stream-sediment samples from Prince Georges County, Maryland originally located in the Baltimore quadrangle now plot in the adjacent Washington quadrangle.
  4. The latitude and longitude coordinates for 5 stream-sediment samples collected within Arlington(5) County in Virginia were not found in the data during the reformatting process. The records for these 5 samples cannot be retrieved on a geographical basis.
  5. Gold concentrations from the GJBX-135(82) report were added to the appropriate sediment records. A value of -0.01 (<0.01 ppm Au) was added to all other sediment samples determined to have been analyzed by SRL neutron activation. This value was chosen because 0.01 is the lowest reported gold concentration in the entire report.

Water Records
The Washington quadrangle water data consist of reformatted records from the Maryland and Virginia portions of the Delaware, Maryland, Virginia, and West Virginia [GJBX-103(82)] Data Report. The following problems were found and addressed during the comparison and reformatting stages for the Washington quadrangle water data:

  1. Two surface-water samples were not included in the original digital data file for Virginia: These records were manually entered from the Virginia portion of the Delaware, Maryland, Virginia, and West Virginia Data Report [GJBX-103(82)].
  2. The original NURE format for surface-water files did not include much information about the character of the sample location. This missing information includes observations taken at each site on the stream width, depth, and flow, water color, surrounding vegetation, local relief, weather, and possible contaminants. This information is given in records for stream-sediment samples that were collected at the same locations. The available site descriptive information for stream-water sites were compared with the corresponding stream-sediment site records. The missing site descriptive data were then added to stream-water records from the corresponding stream-sediment sample records. Sources of data and any problems found are described in the REFORMAT comment field.
  3. During reformatting, contamination codes for "residential" and "recreation" were found to be missing from each State's CONTAMC field. The presence of one of these two codes was indicated only by a "." (period). The missing codes were assigned a value of "unknown" in the CONTAMC field within the final sediment data file.
  4. Unlikely sample collection dates were found for seven samples. These dates were removed from the SAMPDAT field. For each record, the original SAMPDAT value and the most likely correct value was added as a comment to the REFORMAT field.
  5. Eight ground-water samples were identified with a SRLID in the 700's. All of these samples were missing latitude and longitude coordinates. Evidence from original sample site field notes strongly suggests that these are duplicate samples collected later from a previously sampled 500's series site (i.e. SRLID site number ABCD718R is the same location as ABCD518R). The coordinates from the original 500's series sites were added to the matching 700's records and this change was noted in the REFORMAT and COORDPRB comment fields.
  6. An analysis of latitude-longitude site coordinates identified several stream-water samples that were missing coordinates, did not plot within expected state, county, or map boundaries, or had differing coordinates in corresponding records. To correct or confirm sample coordinates, the original field collection maps for Prince Georges County, Maryland were obtained and re-digitized. The newly re-digitized coordinates were added to the database and the coordinates from the original file(s) were recorded in the COORDPRB comment field. When the newly re-digitized coordinates were not significantly different, that confirmation of the site location was also noted in the COORDPRB comment field.
  7. After re-digitizing, seven stream-water samples from Prince Georges County, Maryland originally located in the Baltimore quadrangle now plot in the adjacent Washington quadrangle.
  8. The latitude and longitude coordinates for 7 water samples collected within Arlington(6) and Fairfax(1) Counties in Virginia were not found in the data during the reformatting process. The records for these 7 samples cannot be retrieved on a geographical basis.


Download The Data

The NURE HSSR data are now available online in two databases: The sediment database (also includes data for soils and some rocks) at http://tin.er.usgs.gov/nure/sediment/ and the water database at http://tin.er.usgs.gov/nure/water/. From these two web sites, NURE HSSR data can be selected, examined, summarized, and downloaded by political boundaries (State and County), by quadrangle (1:250,000-scale, 1:100,000-scale, and 1:63,360-scale for Alaska or 1:24,000-scale for the Lower 48 States), and by hydrologic unit (drainage region, subregion, river basin, or sub-basin). Selected data can be downloaded as a dBase file, a shapefile, an HTML table, or ASCII text (tab- or comma-delimited).

Washington Quadrangle Sediment Data - 736 records
Washington Quadrangle Water Data - 929 records



Notes for Data Users

In the eastern United States, SRL collected samples primarily by county. Often, not all counties within a quadrangle were completely sampled. Sample coverage in the Washington quadrangle is complete and includes samples from Anne Arundel, Calvert, Charles, Dorchester, Montgomery, Prince Georges, Queen Annes, St. Marys, and Talbot Counties in Maryland; and Arlington, Caroline, Culpeper, Essex, Fairfax, Fauquier, King George, Loudoun, Louisa, Northumberland, Orange, Prince William, Richmond, Spotsylvania, Stafford, and Westmoreland Counties in Virginia. The laboratory and analytical methods used also may vary by county such that adjacent counties often have very different analytical coverage.

Six stream-sediment samples within the Washington quadrangle were not analyzed by any of the various laboratories. The following table summarizes the locations of those unanalyzed samples.

General locations of unanalyzed samples.
State County Unanalyzed Samples Total Samples
Maryland Calvert 1 30
Maryland Talbot 3 26
Virginia Caroline 2 29




Other NURE Geochemical Data for the Washington Quadrangle

None found.



Washington Quadrangle NURE Bibliography



Links Within Open-File Report 97-492

Back to Maryland NURE data
Back to Virginia NURE data
Frequently Asked Questions Concerning NURE Data
Home Page: USGS National Geochemical Database - NURE HSSR data



Page written by Bryan G. Moravec and Steven M. Smith.
Contact: Steven M. Smith (smsmith@usgs.gov)
Version 1.41: February 23, 2006

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