Paul E. Stackelberg
Zoltan Szabo
Bryant Jurgens
2017
Data for Radium Mobility and the Age of Groundwater in Public-drinking-water Supplies from the Cambrian-Ordovician Aquifer System, North-Central USA: Table 1. Dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age of groundwater by calibration of lumped parameter models to tracer concentrations.
Tabular Digital Data
Reston, VA
U.S. Geological Survey
https://doi.org/10.5066/F7BR8QP0
Paul E. Stackelberg
Zoltan Szabo
Bryant Jurgens
2017
Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA
Journal Article
Amsterdam, Netherlands
Applied Geochemistry
https://doi.org/10.1016/j.apgeochem.2017.11.002
High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers ( 3H, 3Hetrit, SF6 , 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined Ra (Rac = 226Ra + 228Ra) at concentrations exceeding the USEPA MCL of 185 mBq/L (5 pCi/L). The distribution of the three Ra isotopes comprising total Ra (Rat = 224Ra + 226Ra + 228Ra) differed across the aquifer system. The concentrations of 224Ra and 228Ra were strongly correlated and comprised a larger proportion of the Rat concentration in samples from the regionally unconfined area, where arkosic sandstones provide an enhanced source for progeny from the 232Th decay series. 226Ra comprised a larger proportion of the Rat concentration in samples from downgradient confined regions. Concentrations of Rat were significantly greater in samples from the regionally confined area of the aquifer system because of the increase in 226Ra concentrations there as compared to the regionally unconfined area. 226Ra distribution coefficients decreased substantially with anoxic conditions and increasing ionic strength of groundwater (mineralization), indicating that Ra is mobilized to solution from solid phases of the aquifer as sorption capacity is diminished. The amount of 226Ra released from solid phases by alpha-recoil mechanisms and retained in solution increases relative to the amount of Ra sequestered by adsorption processes or co-precipitation with barite as sorption capacity and the concentration of Ba decreases. Although 226Ra occurred at concentrations greater than 224Ra or 228Ra, the ingestion exposure risk was greater for 228Ra owing to its greater toxicity. In addition, 224Ra added substantial alpha-particle radioactivity to potable samples from the C-O aquifer system. Thus, monitoring for Ra isotopes and gross-alpha-activity (GAA) is important in upgradient, regionally unconfined areas as downgradient, and GAA measurements made within 72 h of sample collection would best capture alpha-particle radiation from the short-lived 224Ra.
Dissolved gas and environmental tracer data were collected from drinking-water wells that withdraw water from the Cambrian-Ordovician in 2014 to understand the age and vulnerability of the aquifer to natural and anthropogenic contaminants.
CamOrd_Radium_Table1.xlsx contains dissolved gas modeling results, environmental tracer concentrations (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), and results for the mean age of groundwater by calibration of lumped parameter models to tracer concentrations (Jurgens and others, 2012). Dissolved gas modeling and environmental tracer results were averaged when multiple dissolved gas models and tracer concentrations were computed in CamOrd_Radium_Table2.xlsx and CamOrd_Radium_Table3.xlsx. In cases where age was modeled with a binary lumped parameter model (LPM), the mean age was computed from the mean age and fraction of the two components in the mixture. Please see the processing steps below and the main manuscript for additional details on the results presented in this table.
CamOrd_Radium_Table_Structures_and_Abbreviations.xlsx contains a description of each tables's structure, a list of abbreviations contained in the tables, and the definition of each abbreviation.
20140326
20141001
ground condition
Not planned
-97.514648437199
-82.22167968781
49.410688528111
35.924290222685
USGS Thesaurus
radium
groundwater age
Cambrian-Ordovician aquifer system
radium 226 distribution coefficient
alpha recoil
dissolved gas
lumped parameter modeling
recharge temperature
NAWQA
nawqa
cycle 3
water quality
USGS Metadata Identifier
USGS:59ea88bee4b0026a55fd0137
Geographic Names Information System (GNIS)
Illinois
Iowa
Michigan
Minnesota
Wisconsin
None. Please see 'Distribution Information' for details.
Acknowledgment of the Originator when using the dataset as a source. Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations.
Paul E Stackelberg
U.S. Geological Survey
mailing and physical
425 Jordan Road
Troy
NY
12180
United States
518-285-5652
pestack@usgs.gov
National Water-Quality Assessment project
Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.3.1 (Build 4959) Service Pack N/A (Build N/A)
Data are checked by individual U.S. Geological Survey science center personnel before entry into the National Water Information System (NWIS).
Results from TracerLPM are documented in Jurgens, B.C., Böhlke, J.K., and Eberts, S.M., 2012, TracerLPM (Version 1): An Excel® workbook for interpreting groundwater age distributions from environmental tracer data: U.S. Geological Survey Techniques and Methods Report 4-F3, 60 p.
No formal logical accuracy tests were conducted
Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
No formal positional accuracy tests were conducted
No formal positional accuracy tests were conducted
Aeschbach-Hertig, W.
Peeters, F.
Beyerle, U.
Kipfer, R.
1999
Interpretation of dissolved atmospheric noble gases in natural waters
Publication
Hoboken, NJ
Water Resources Research
Aeschbach-Hertig, W., F. Peeters, U. Beyerle, and R. Kipfer, 1999, Interpretation of dissolved atmospheric noble gases in natural waters, Water Resources Research, 35(9), 2779–2792, https://doi.org/10.1029/1999WR900130
https://doi.org/10.1029/1999WR900130
Digital and/or Hardcopy Resources
19990101
19991231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
John N. Andrews
David J. Lee
1979
Inert gases in groundwater from the Bunter Sandstone of England as indicators of age and palaeoclimatic trends
Publication
Amsterdam, The Netherlands
Journal of Hydrology
Andrews, J.N. and Lee, D.J., 1979, Inert gases in groundwater from the Bunter Sandstone of England as indicators of age and palaeoclimatic trends: Journal of Hydrology 41, 233-252, https://doi.org/10.1016/0022-1694(79)90064-7
https://doi.org/10.1016/0022-1694(79)90064-7
Digital and/or Hardcopy Resources
19780922
19781215
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Eurybiades Busenberg
L. Niel Plummer
2000
Dating young groundwater with sulfur hexafluoride: Natural and anthropogenic sources of sulfur hexafluoride
Publication
Hoboken, NJ
Water Resources Research
Busenberg, E., and L. N. Plummer, 2000, Dating young groundwater with sulfur hexafluoride: Natural and anthropogenic sources of sulfur hexafluoride, Water Resources Research, 36(10), 3011–3030, https://doi.org/10.1029/2000WR900151
https://doi.org/10.1029/2000WR900151
Digital and/or Hardcopy Resources
20000101
20001231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Quan Hua
Mike Barbetti
Andrzej Z. Rakowski
2013
Atmospheric radiocarbon for the period 1950-2010
Publication
New York, NY
Radiocarbon
Hua, Q., Barbetti, M., and Rakowski, A.Z., 2013, Atmospheric radiocarbon for the period 1950-2010: Radiocarbon, v. 55, no. 4, p. 2059–2072, https://doi.org/10.2458/azu_js_rc.v55i2.16177.
https://doi.org/10.2458/azu_js_rc.v55i2.16177
Digital and/or Hardcopy Resources
19500101
20101231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Andrew G. Hunt
20150812
U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples
Publication
Reston, VA
U.S. Geological Survey
Hunt, A.G., 2015, Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples: U.S. Geological Survey Techniques and Methods, book 5, chap. A11, 22 p., https://dx.doi.org/10.3133/tm5A11
https://dx.doi.org/10.3133/tm5A11
Digital and/or Hardcopy Resources
20150812
20150813
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Bryant C. Jurgens
J.K. Bohlke
Sandra M. Eberts
2012
TracerLPM (version 1): An Excel workbook for interpreting groundwater age distributions from environmental tracers
Publication
Reston, VA
U.S. Geological Survey
Jurgens, B.C., Böhlke, J.K., and Eberts, S.M., 2012, TracerLPM (Version 1): An Excel® workbook for interpreting groundwater age distributions from environmental tracer data: U.S. Geological Survey Techniques and Methods Report 4-F3, 60 p., https://pubs.usgs.gov/tm/4-f3/
https://pubs.usgs.gov/tm/4-f3/
Digital Resource
20120101
20121231
publication date
TracerLPM
Software used for evaluating groundwater age distributions from environmental tracer data by using lumped parameter models (LPMs).
George Edward Manger
1963
Porosity and bulk density of sedimentary rocks
Publication
Reston, VA
U.S. Geological Survey
Manger, G.E., 1963, Porosity and bulk density of sedimentary rocks, in: U.S. Geological Survey Bulletin 1144-E (Ed.), p. 55., https://pubs.usgs.gov/bul/1144e/report.pdf
https://pubs.usgs.gov/bul/1144e/report.pdf
Digital and/or Hardcopy Resources
19630101
19631231
publication date
Data Collection Protocols and Procedures
This report describes protocols and recommended procedures for the collection of water-quality samples and related data from wells for the NAWQA Program.
Robert L. Michel
1989
Tritium deposition over the continental United States, 1953-1983
Publication
Reston, VA
U.S. Geological Survey
Michel, R.L., 1989, Tritium deposition over the continental United States, 1953-1983 in: Atmospheric Deposition (Proceedings of the Baltimore Symposium, May 1989, IAHS Publ. No. 179, http://hydrologie.org/redbooks/a179/iahs_179_0109.pdf
http://hydrologie.org/redbooks/a179/iahs_179_0109.pdf
Digital and/or Hardcopy Resources
19530101
19831231
publication date
Data Collection Protocols and Procedures
This report describes protocols and recommended procedures for the collection of water-quality samples and related data from wells for the NAWQA Program.
National Ocean Sciences Accelerator Mass Spectrometry Facility
2015
General statement of 14C procedures at the National Ocean Sciences AMS Facility
Web Page
Woods Hole, MA
Woods Hole Oceanographic Institution
National Ocean Sciences Accelerator Mass Spectrometry Facility, 2015, General statement of 14C procedures at the National Ocean Sciences AMS Facility: Woods Hole Oceanographic Institution, accessed July 2016 at http://www.whoi.edu/nosams/general-statement-of-14c-procedures
http://www.whoi.edu/nosams/general-statement-of-14c-procedures
Digital Resources
20150101
20170908
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Jeffrey D. Phillips
Joseph S. Duval
Russell A. Ambroziak
1993
National geophysical data grids; gamma-ray, gravity, magnetic, and topographic data for the conterminous United States
Publication
Reston, VA
U.S. Geological Survey
Phillips, J. D., Duval, J. S., and Ambroziak, R. A., 1993, National geophysical data grids; gamma-ray, gravity, magnetic, and topographic data for the conterminous United States: U.S. Geological Survey Digital Data Series DDS-9, accessed August 30, 2010 at URL http://crustal.usgs.gov/geophysics/North_America.html.
http://crustal.usgs.gov/geophysics/North_America.html
Digital Resources
19930101
19931231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Paula J. Reimer
Edouard Bard
Alex Bayliss
J. Warren Beck
Paul G. Blackwell
Christopher Bronk Ramsey
Caitlin E. Buck
Hai Cheng
R. Lawrence Edwards
Michael Friedrich
Pieter M. Grootes
Thomas P. Guilderson
Haflidi Haflidason
Irka Hajdas
Christine Hatté
Timothy J. Heaton
Dirk L. Hoffmann
Alan G. Hogg
Konrad A. Hughen
K. Felix Kaiser
Bernd Kromer
Sturt W. Manning
Mu Niu
Ron W. Reimer
David A. Richards
E. Marian Scott
John R. Southon
Richard A. Staff
Christian S. M. Turney
Johannes van der Plicht
2013
IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP
Publication
The University of Arizona
Radiocarbon
Reimer, P. J.; Bard, Edouard; Bayliss, Alex; Beck, J. W.; Blackwell, P. G.; Bronk Ramsey, Christopher; Buck, C. E.; Cheng, H.; Edwards, R. L.; Friedrich, M.; Grootes, P. M.; Guilderson, T. P.; Haflidason, H.; Hajdas, Irka; Hatte, C; Heaton, T. J.; Hoffman, D.L.; Hogg, A. G.; Hughen, K. A.; Kaiser, K. F.; Kromer, B.; Manning, S. W.; Niu, M.; Reimer, R. W.; Richards, D. A.; Scott, E.M.; Southon, J. R.; Staff, R.A.; Turney, C. S. M.; and Van Der Plicht, Johannes, 2013, IntCal13 and Marine13 radiocarbon age calibration curves, 0–50,000 years cal BP: Radiocarbon, v. 55., no. 4, p. 1869–1887, https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/16947
https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/16947
Digital Resources
19930101
19931231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
D. Kip Solomon
Peter G. Cook
2000
3H and 3He
Publication
Boston, MA
Kluwer Academic Publishers
Solomon D.K. and Cook P.G., 2000, 3H and 3He. In: Cook P.G., Herczeg A.L. (eds) Environmental Tracers in Subsurface Hydrology. Springer, Boston, MA
Digital Resources
20000101
20001231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
D. Kip Solomon
2000
4He in groundwater
Publication
Boston, MA
Kluwer Academic Publishers
Solomon D.K., 2000, 4He in groundwater. In: Cook P.G., Herczeg A.L. (eds) Environmental Tracers in Subsurface Hydrology. Springer, Boston, MA
Digital Resources
20000101
20001231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Thatcher, L.L.
Janzer, V.J.
Edwards, K.W.
1977
Methods for the determination of radioactive substances in water
Publication
Reston, VA
U.S. Geological Survey
Thatcher, L.L., Janzer, V.J., and Edwards, K.W., 1977, Methods for the determination of radioactive substances in water: U.S. Geological Survey Techniques of Water-Resources Investigations, book 5, chap. A5, 95 p., https://pubs.usgs.gov/twri/twri5a5/
https://pubs.usgs.gov/twri/twri5a5/
Digital Resources
19770101
19771231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
U.S. Geological Survey
2010
The Reston Chlorofluorocarbon Laboratory, analytical procedures for dissolved gas
Web Page
Reston, VA
U.S. Geological Survey
U.S. Geological Survey, 2010, The Reston Chlorofluorocarbon Laboratory, analytical procedures for dissolved gas, accessed September 2010 at http://water.usgs.gov/lab/dissolved-gas/lab/analytical_procedures/
http://water.usgs.gov/lab/dissolved-gas/lab/analytical_procedures/
Digital Resources
20150101
20151231
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
U.S.Geological Survey
2016
CFC and SF6 Air Curves
Web Site
Reston, VA
U.S.Geological Survey
U.S. Geological Survey, 2016, CFC and SF6 Air Curves: U.S. Geological Survey Web Site, https://water.usgs.gov/lab/software/air_curve/index.html.
https://water.usgs.gov/lab/software/air_curve/index.html
Digital Resources
19970101
20150101
publication date
Water-Quality Data Collection
Web site provides protocols (requirements and recommendations) and guidelines for USGS personnel who are responsible for the collection and quality assurance of such data.
Weiss, R.F.
1970
The solubility of nitrogen, oxygen and argon in water and seawater
Publication
Amsterdam, The Netherlands
Deep Sea Research and Oceanographic Abstracts
Weiss, R. F., 1970, The solubility of nitrogen, oxygen, and argon in water and seawater, Deep Sea Research, vol. 17, pp. 721-735, https://doi.org/10.1016/0011-7471(70)90037-9
https://doi.org/10.1016/0011-7471(70)90037-9
Digital and/or Hardcopy Resources
19700112
19700113
publication date
Data Collection Protocols and Procedures
Reference for data analysis and interpretation
Concentrations of sulfur hexafluoride (SF6) in femtomoles per kilogram and argon and nitrogen in milligrams per liter were analyzed at the USGS Groundwater Dating Laboratory (formerly Reston Chlorofluorocarbon Laboratory; U.S. Geological Survey, 2010). Concentrations of noble gases (helium, neon, argon, xenon, and nitrogen) in cubic centimeters at standard temperature and pressure per gram of water and helium isotopes were analyzed at the USGS Noble Gas Laboratory (Hunt, 2015). Concentrations of carbon-14 (14C) in percent modern (pM) were analyzed at Woods Hole Oceanographic Institute were de-normalized and converted to percent modern carbon (pmC) for age dating analysis (National Ocean Sciences Accelerator Mass Spectrometry Facility, 2015). Tritium (3H) was analyzed by electrolytic enrichment-liquid scintillation at the USGS Stable Isotope and Tritium Laboratory in Menlo Park, California (Thatcher et al., 1977).
Regional histories of atmospheric tracers in recharge were compiled and used as input to the program TracerLPM [Jurgens et al., 2012] for computing groundwater ages. Tritium concentrations in precipitation from 1953 to 2002 for the area covering the Cambrian-Ordovician aquifer system were estimated from updated monthly 3H data. Atmospheric tritium records were compiled for 10 latitude-longitude combinations covering the Cambrian-Ordovician aquifer system (Michel, 1989; written communication, 2011). Northern Hemisphere atmospheric mixing ratios of SF6 were obtained from the U.S. Geological Survey Groundwater Dating Laboratory (U.S. Geological Survey, 2016). Atmospheric records of 14C were compiled by combining data from the 2013 international radiocarbon calibration curve (IntCal13; Reimer et al., 2013) with modern historical tropospheric 14C data for the northern hemisphere (zone 2; Hua and others, 2013). Graphical relationships between measured 3H, tritiogenic helium-3 (3Hetrit), SF6, and 14C indicated that concentrations of 14C have been diluted by 14C-free sources of 14C in water recharged since 1950. Dilution of the atmospheric 14C signal was estimated to be about 30% (i.e 70% of the atmospheric signal) and this dilution was likely caused by the dissolution of soil carbonates during infiltration of precipitation in recharge areas of the Cambrian-Ordovician aquifer system. Additional dilution of 14C in the saturated zone may also occur from dissolution of dolomite and limestone sequences of the aquifer but these reactions were not accounted for in the modeling of groundwater ages using 14C. Without correction for these reactions, mean groundwater ages will be older but differences between corrected and uncorrected ages may only be a few thousand years in most samples. Radiogenic helium (4Herad) concentrations were calculated using a helium production rate of 1.89 X 10-10 cubic centimeters at standard temperature and pressure per gram of water (cc/g) of water, which was 50 times the natural production rate of 3.78 X 10-12. The natural production rate was determined from using the equation of Andrews and Lee (1979) with average uranium and thorium sediment concentrations of 1.63 and 5.23 ppm, respectively (Phillips el al., 1993), a porosity of 0.2, and a bulk density of 2.2 (Manger, 1963).
Mean groundwater ages were computed by calibrating lumped parameter models (LPMs) to concentrations of tracers (3H, 3Hetrit, SF6, 14C, and 4Herad) in samples using the computer program TracerLPM (Jurgens and others, 2012). The LPM used to compute final groundwater ages reported in table 1 was based on sample 3H activities. The dispersion model (DM) was used to determine groundwater ages for samples with 3H equal to or above 4 Tritium units (TU) because this activity was indicative of water that had been recharged entirely or almost entirely since 1950. Six samples had 3H from about 4 to 6 TU and these samples usually were accompanied with measureable amounts of 3Hetrit and SF6. Mean groundwater ages for these samples ranged from 19.6 to 29.2 years. The piston-flow model (PFM) was used to determine mean groundwater ages for samples with 3H below 0.3 TU. This activity was indicative of water that that had been recharged entirely or almost entirely before 1950. Since 3H was largely absent in these samples, the PFM was calibrated to 4Herad concentrations or to 14C concentrations when 4Herad was less than 2 times the solubility concentration of helium, which was about 4.5 X 10-8. The PFM was computed for 64 (80% of samples) samples and mean groundwater ages for these samples ranged from 61.5 to over 1.4 million years. A binary dispersion-piston-flow model (BMM-DM-PFM) was used to determine mean groundwater ages for samples with 3H between 0.3 and 4 TU because these samples are mixtures of groundwater with a distinct portion of the water recharged after 1950 and another portion that was recharged before 1950, commonly 1,000 years or more. Nine samples were modeled as binary mixtures and the fraction of young water in the mixtures ranged from 1% to 53%. Additional details about the models and ages derived from them are given in the manuscript associated with this data release.
2014
2014
2014
Table 1 Excel File
Table containing dissolved gas modeling results
U.S. Geological Survey
Sample Information: Study Unit
Sample group 1
U.S. Geological Survey
Location of sample group 1. Column A in spreadsheet.
Sample Information: Study Area
Sample group 2
U.S. Geological Survey
Location of sample group 2. Column B in spreadsheet.
Sample Information: USGS Station ID
USGS Station identification no.
U.S. Geological Survey
USGS Station identification no. Column C in spreadsheet.
Sample Information: Site ID
Site identification no.
U.S. Geological Survey
Site identification no. Column D in spreadsheet.
Sample Information: Sample Date
Date of sample
U.S. Geological Survey
Date of sample. Column E in spreadsheet.
Modeling Results: Noble Gas Model
Name of noble gas model used in optimization
U.S. Geological Survey
Name of noble gas model used in optimization. Column F in spreadsheet.
Modeling Results: Model Parameters
Short name of model parameters included in optimization
U.S. Geological Survey
Short name of model parameters included in optimization. Column G in spreadsheet.
Modeling Results: Chi-Square
Chi square test statistic (sum of weighted squared residuals)
U.S. Geological Survey
Chi square test statistic (sum of weighted squared residuals). Column H in spreadsheet.
Modeling Results: Probability
Chi-square probability of chi-square error when degrees of freedom is greater than 1
U.S. Geological Survey
Chi-square probability of chi-square error when degrees of freedom is greater than 1. Column I in spreadsheet.
Modeling Results: Salinity, per mil
Salinity of water, in per mil
U.S. Geological Survey
Salinity of water, in per mil. Column J in spreadsheet.
Modeling Results: Salinity Err, 1-Sigma
Salinity of water error (1-sigma), in per mil
U.S. Geological Survey
Salinity of water error (1-sigma), in per mil. Column K in spreadsheet.
Modeling Results: Recharge Elevation, meters
Elevation of recharge area, in meters above land surface
U.S. Geological Survey
Elevation of recharge area, in meters above land surface. Column L in spreadsheet.
Modeling Results: Recharge Elevation Err, 1-Sigma
Recharge elevation error (1-sigma), in meters above land surface
U.S. Geological Survey
Recharge elevation error (1-sigma), in meters above land surface. Column M in spreadsheet.
Modeling Results: Recharge Temp, degrees Celsius
Temperature of water at time of recharge, in degrees Celsius
U.S. Geological Survey
Temperature of water at time of recharge, in degrees Celsius. Column N in spreadsheet.
Modeling Results: Recharge Temp Err, 1-Sigma
Temperature error (1-sigma), in degrees Celsius
U.S. Geological Survey
Temperature error (1-sigma), in degrees Celsius. Column O in spreadsheet.
Modeling Results: Excess Air / Entrapped Air, cc STP/kg of H2O
Excess air or entrapped air of water at time of recharge, in cubic centimeters per kilogram of water
U.S. Geological Survey
Excess air or entrapped air of water at time of recharge, in cubic centimeters per kilogram of water. Column P in spreadsheet.
Modeling Results: Excess Air / Entrapped Air Err, 1-Sigma
Excess air or entrapped air error (1-sigma), in cubic centimeters per kilogram of water
U.S. Geological Survey
Excess air or entrapped air error (1-sigma), in cubic centimeters per kilogram of water. Column Q in spreadsheet.
Modeling Results: Fractionation, dimensionless
Fractionation factor of gases (CE or PR models) of water at time of recharge, dimensionless
U.S. Geological Survey
Fractionation factor of gases (CE or PR models) of water at time of recharge, dimensionless. Column R in spreadsheet.
Modeling Results: Fractionation Err, 1-Sigma
Fractionation error (1-sigma), dimensionless
U.S. Geological Survey
Fractionation error (1-sigma), dimensionless. Column S in spreadsheet.
Modeling Results: Excess Nitrogen, mg/L as N
Amount of nitrogen gas that is in excess of solubility and excess air component, in milligrams per liter as nitrogen
U.S. Geological Survey
Amount of nitrogen gas that is in excess of solubility and excess air component, in milligrams per liter as nitrogen. Column T in spreadsheet.
Modeling Results: Excess Nitrogen Err, 1-Sigma
Excess nitrogen gas error (1-sigma), in milligrams per liter as nitrogen
U.S. Geological Survey
Excess nitrogen gas error (1-sigma), in milligrams per liter as nitrogen. Column U in spreadsheet.
Tracer Concentrations: Tritium, TU
Tritium, in tritium units
U.S. Geological Survey
Tritium, in tritium units. Column V in spreadsheet.
Tracer Concentrations: Tritium error, TU
Tritium error, in tritium units
U.S. Geological Survey
Tritium error, in tritium units. Column W in spreadsheet.
Tracer Concentrations: SF6, pptv
Sulfur hexafluoride, in parts per trillion by volume (pptv)
U.S. Geological Survey
Sulfur hexafluoride, in parts per trillion by volume (pptv). Column X in spreadsheet.
Tracer Concentrations: SF6 error, pptv
Sulfur hexafluoride error, in parts per trillion by volume (pptv)
U.S. Geological Survey
Sulfur hexafluoride error, in parts per trillion by volume (pptv). Column Y in spreadsheet.
Tracer Concentrations: Reported 3He trit., TU
Reported tritiogenic helium-3, TU
U.S. Geological Survey
Reported tritiogenic helium-3, TU. Column Z in spreadsheet.
Tracer Concentrations: Reported 3He trit. error, TU
Reported tritiogenic helium-3 error, TU
U.S. Geological Survey
Reported tritiogenic helium-3 error, TU. Column AA in spreadsheet.
Tracer Concentrations: 14C, pmC
Carbon-14 in percent modern Carbon
U.S. Geological Survey
Carbon-14 in percent modern Carbon. Column AB in spreadsheet.
Tracer Concentrations: 14C error, pmC
Carbon-14 error in percent modern Carbon
U.S. Geological Survey
Carbon-14 error in percent modern Carbon. Column AC in spreadsheet.
Tracer Concentrations: 4He, cc STP/g of H2O
Radiogenic helium in cubic centimeters at standard temperature and pressure per gram of water
U.S. Geological Survey
Radiogenic helium in cubic centimeters at standard temperature and pressure per gram of water. Column AD in spreadsheet.
Tracer Concentrations: 4He error, cc STP/g of H2O
Radiogenic helium error in cubic centimeters at standard temperature and pressure per gram of water
U.S. Geological Survey
Radiogenic helium error in cubic centimeters at standard temperature and pressure per gram of water. Column AE in spreadsheet.
Lumped Parameter Modeling Results: Final mean age, years
Mean age of groundwater sample
U.S. Geological Survey
Mean age of groundwater sample. Column AF in spreadsheet.
Lumped Parameter Modeling Results: Fraction of young water
Fraction of water less than about 60 years
U.S. Geological Survey
Fraction of water less than about 60 years. Column AG in spreadsheet.
Lumped Parameter Modeling Results: LPM name
Name of lumped parameter model
U.S. Geological Survey
Name of lumped parameter model. Column AH in spreadsheet.
Lumped Parameter Modeling Results: Free Model Parameters
Model parameters to be optimized
U.S. Geological Survey
Model parameters to be optimized. Column AI in spreadsheet.
Lumped Parameter Modeling Results: Chi-Square (sum of weighted squared residuals)
Optimized chi-square error (sum of weighted squared resdiuals) of model solution
U.S. Geological Survey
Optimized chi-square error (sum of weighted squared resdiuals) of model solution. Column AJ in spreadsheet.
Lumped Parameter Modeling Results: Chi-Square Probability
Chi-square probability of chi-square error when degrees of freedom is greater than 1
U.S. Geological Survey
Chi-square probability of chi-square error when degrees of freedom is greater than 1. Column AK in spreadsheet.
Lumped Parameter Modeling Results: UZ travel time, years
Unsaturated zone travel time in years (assuming piston flow transport of tracer)
U.S. Geological Survey
Unsaturated zone travel time in years (assuming piston flow transport of tracer). Column AL in spreadsheet.
Lumped Parameter Modeling Results: UZ travel time error, years
Unsaturated zone travel time error in years (assuming piston flow transport of tracer)
U.S. Geological Survey
Unsaturated zone travel time error in years (assuming piston flow transport of tracer). Column AM in spreadsheet.
Lumped Parameter Modeling Results: Mean age, years
Mean age of primary lumped parameter model
U.S. Geological Survey
Mean age of primary lumped parameter model. Column AN in spreadsheet.
Lumped Parameter Modeling Results: Mean age error, years
Mean age error of primary lumped parameter model
U.S. Geological Survey
Mean age error of primary lumped parameter model. Column AO in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 1
PEM upper ratio, Dispersion parameter (DP), EPM ratio of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio of the primary lumped parameter model. Column AP in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 1 error
PEM upper ratio, Dispersion parameter (DP), EPM ratio error of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio error of the primary lumped parameter model. Column AQ in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 2
PEM lower ratio, alpha parameter for FDM of the primary lumped paramerer model
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) of the primary lumped paramerer model. Column AR in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 2 error
PEM lower ratio, alpha parameter for FDM error of the primary lumped paramerer model
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) error of the primary lumped paramerer model. Column AS in spreadsheet.
Lumped Parameter Modeling Results: Fraction
Fraction of component 1
U.S. Geological Survey
Fraction of component 1. Column AT in spreadsheet.
Lumped Parameter Modeling Results: Fraction error
Fraction error of component 1
U.S. Geological Survey
Fraction error of component 1. Column AU in spreadsheet.
Lumped Parameter Modeling Results: Mean age, years
Mean age of second component in binary mixture
U.S. Geological Survey
Mean age of second component in binary mixture. Column AV in spreadsheet.
Lumped Parameter Modeling Results: Mean age error, years
Mean age error of second component in binary mixture
U.S. Geological Survey
Mean age error of second component in binary mixture. Column AW in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 1
PEM upper ratio, Dispersion parameter (DP), EPM ratio of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio of second component of binary mixture. Column AX in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 1 error
PEM upper ratio, Dispersion parameter (DP), EPM ratio error of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio error of second component of binary mixture. Column AY in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 2
PEM lower ratio, alpha parameter for FDM of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) of second component of binary mixture. Column AZ in spreadsheet.
Lumped Parameter Modeling Results: Model Parameter 2 error
PEM lower ratio, alpha parameter for FDM error of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) error of second component of binary mixture. Column BA in spreadsheet.
Lumped Parameter Modeling Results: Tracers Modeled
Tracers used to calibrate lumped parameter model
U.S. Geological Survey
Tracers used to calibrate lumped parameter model. Column BB in spreadsheet.
Lumped Parameter Modeling Results: HiTracer
Tracer with the highest contribution to chi-square
U.S. Geological Survey
Tracer with the highest contribution to chi-square. Column BC in spreadsheet.
Lumped Parameter Modeling Results: Hi Tracer Chi-Sqr
Chi-square error of the HiTracer
U.S. Geological Survey
Chi-square error of the HiTracer. Column BD in spreadsheet.
Lumped Parameter Modeling Results: Number of iterations
Number of iterations to find solution
U.S. Geological Survey
Number of iterations to find solution. Column BE in spreadsheet.
Lumped Parameter Modeling Results: Model solution time, seconds
Elapsed time to find model solution
U.S. Geological Survey
Elapsed time to find model solution. Column BF in spreadsheet.
Lumped Parameter Modeling Results: Model date stamp
Date and time the model was computed
U.S. Geological Survey
Date and time the model was computed. Column BG in spreadsheet.
Modeled Tracer Data: 3H, in TU
Modeled concentration of tracer 1 (Tritium, in tritium units)
U.S. Geological Survey
Modeled concentration of tracer 1 (Tritium, in tritium units). Column BH in spreadsheet.
Modeled Tracer Data: 3He(trit), in TU
Modeled concentration of tracer 2 (Tritiogenic Helium-3, in tritium units)
U.S. Geological Survey
Modeled concentration of tracer 2 (Tritiogenic Helium-3, in tritium units). Column BI in spreadsheet.
Modeled Tracer Data: 3Ho, in TU
Modeled concentration of tracer 3 (Initial Tritium, in tritium units)
U.S. Geological Survey
Modeled concentration of tracer 3 (Initial Tritium, in tritium units). Column BJ in spreadsheet.
Modeled Tracer Data: 3H/3Ho, ratio
Modeled concentration of tracer 4 (Tritium / Initial tritium ratio, unitless)
U.S. Geological Survey
Modeled concentration of tracer 4 (Tritium / Initial tritium ratio, unitless). Column BK in spreadsheet.
Modeled Tracer Data: SF6, in pptv
Modeled concentration of tracer 5 (Sulfur Hexafluoride, in parts per trillion by volume)
U.S. Geological Survey
Modeled concentration of tracer 5 (Sulfur Hexafluoride, in parts per trillion (10^-12) by volume). Column BL in spreadsheet.
Modeled Tracer Data: NO3-N, in mg/L as N
Modeled concentration of tracer 6 (Nitrate in recharge, milligrams per liter as nitrogen)
U.S. Geological Survey
Modeled concentration of tracer 6 (Nitrate in recharge, milligrams per liter as nitrogen). Column BM in spreadsheet.
Modeled Tracer Data: Tracer 7, empty
Modeled concentration of tracer 7
U.S. Geological Survey
Modeled concentration of tracer 7. Column BN in spreadsheet.
Modeled Tracer Data: 14C, in pmC
Modeled concentration of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs)
U.S. Geological Survey
Modeled concentration of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs). Column BO in spreadsheet.
Modeled Tracer Data: 4He, cc@STP/gH2O
Modeled concentration of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP per gram of water)
U.S. Geological Survey
Modeled concentration of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP (standard temperature and pressure) per gram of water). Column BP in spreadsheet.
Modeled Tracer Data: Tracer 10, empty
Measured concentration of tracer 10
U.S. Geological Survey
Modeled concentration of tracer 10. Column BQ in spreadsheet.
Measured Tracer Data: 3H, in TU
Measured concentration of tracer 1 (Tritium, in tritium units)
U.S. Geological Survey
Measured concentration of tracer 1 (Tritium, in tritium units). Column BR in spreadsheet.
Measured Tracer Data: 3H, std. err.
Measured error concentrations of tracer 1
U.S. Geological Survey
Measured error concentrations of tracer 1. Column BS in spreadsheet.
Measured Tracer Data: 3He(trit), in TU
Measured concentration of tracer 2 (Tritiogenic Helium-3, in tritium units)
U.S. Geological Survey
Measured concentration of tracer 2 (Tritiogenic Helium-3, in tritium units). Column BT in spreadsheet.
Measured Tracer Data: 3He(trit), std. err.
Measured error concentrations of tracer 2
U.S. Geological Survey
Measured error concentrations of tracer 2. Column BU in spreadsheet.
Measured Tracer Data: Tracer 3, empty
Measured error concentrations of tracer 3
U.S. Geological Survey
Measured error concentrations of tracer 3. Column BV in spreadsheet.
Measured Tracer Data: Tracer 3, std. err.
Measured error concentrations of tracer 3
U.S. Geological Survey
Measured error concentrations of tracer 3. Column BW in spreadsheet.
Measured Tracer Data: Tracer 4, empty
Measured error concentrations of tracer 4
U.S. Geological Survey
Measured error concentrations of tracer 4. Column BX in spreadsheet.
Measured Tracer Data: Tracer 4, std. err.
Measured error concentrations of tracer 4
U.S. Geological Survey
Measured error concentrations of tracer 4. Column BY in spreadsheet.
Measured Tracer Data: SF6, in pptv
Measured concentration of tracer 5 (Sulfur Hexafluoride, in parts per trillion by volume)
U.S. Geological Survey
Measured concentration of tracer 5 (Sulfur Hexafluoride, in parts per trillion (10^-12) by volume). Column BZ in spreadsheet.
Measured Tracer Data: SF6, std. err.
Measured error concentrations of tracer 4
U.S. Geological Survey
Measured error concentrations of tracer 4. Column CA in spreadsheet.
Measured Tracer Data: 14C, in pmC
Measured concentration of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs)
U.S. Geological Survey
Measured concentration of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs). Column CB in spreadsheet.
Measured Tracer Data: 14C, std. err.
Measured error concentrations of tracer 8
U.S. Geological Survey
Measured error concentrations of tracer 8. Column CC in spreadsheet.
Measured Tracer Data: 4He, cc@STP/gH2O
Measured concentration of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP per gram of water)
U.S. Geological Survey
Measured concentration of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP (standard temperature and pressure) per gram of water). Column CD in spreadsheet.
Measured Tracer Data: 4He, std. err.
Measured error concentrations of tracer 9
U.S. Geological Survey
Measured error concentrations of tracer 9. Column CE in spreadsheet.
Measured Tracer Data: Tracer 8, empty
Measured error concentrations of tracer 8
U.S. Geological Survey
Measured error concentrations of tracer 8. Column CF in spreadsheet.
Measured Tracer Data: Tracer 8, std. err.
Measured error concentrations of tracer 8
U.S. Geological Survey
Measured error concentrations of tracer 8. Column CG in spreadsheet.
Measured Tracer Data: Tracer 9, empty
Measured error concentrations of tracer 9
U.S. Geological Survey
Measured error concentrations of tracer 9. Column CH in spreadsheet.
Measured Tracer Data: Tracer 9, std. err.
Measured error concentrations of tracer 9
U.S. Geological Survey
Measured error concentrations of tracer 9. Column CI in spreadsheet.
Measured Tracer Data: Tracer 10, empty
Measured error concentrations of tracer 9
U.S. Geological Survey
Measured error concentrations of tracer 9. Column CJ in spreadsheet.
Measured Tracer Data: Tracer 10, std. err.
Measured error concentrations of tracer 10
U.S. Geological Survey
Measured error concentrations of tracer 10. Column CK in spreadsheet.
Monte Carlo Results: Num. of Monte Carlo sims
Number of Monte Carlo simulations
U.S. Geological Survey
Number of Monte Carlo simulations. Column CL in spreadsheet.
Monte Carlo Results: Simulation time, seconds
Elapsed time to compute Monte Carlo simulations
U.S. Geological Survey
Elapsed time to compute Monte Carlo simulations. Column CM in spreadsheet.
Monte Carlo Results: UZ travel time, years
Unsaturated zone travel time in years (assuming piston flow transport of tracer)
U.S. Geological Survey
Unsaturated zone travel time in years (assuming piston flow transport of tracer). Column CN in spreadsheet.
Monte Carlo Results: UZ travel time error, years
Unsaturated zone travel time error in years (assuming piston flow transport of tracer)
U.S. Geological Survey
Unsaturated zone travel time error in years (assuming piston flow transport of tracer). Column CO in spreadsheet.
Monte Carlo Results: Mean age, years
Mean age of primary lumped parameter model
U.S. Geological Survey
Mean age of primary lumped parameter model. Column CP in spreadsheet.
Monte Carlo Results: Mean age error, years
Mean age error of primary lumped parameter model
U.S. Geological Survey
Mean age error of primary lumped parameter model. Column CQ in spreadsheet.
Monte Carlo Results: Model Parameter 1
PEM upper ratio, Dispersion parameter (DP), EPM ratio of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio of the primary lumped parameter model. Column CR in spreadsheet.
Monte Carlo Results: Model Parameter 1 error
PEM upper ratio, Dispersion parameter (DP), EPM ratio error of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio error of the primary lumped parameter model. Column CS in spreadsheet.
Monte Carlo Results: Model Parameter 2
PEM lower ratio, alpha parameter for FDM of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) of the primary lumped parameter model. Column CT in spreadsheet.
Monte Carlo Results: Model Parameter 2 error
PEM lower ratio, alpha parameter for FDM error of the primary lumped parameter model
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) error of the primary lumped parameter model. Column CU in spreadsheet.
Monte Carlo Results: Fraction
Fraction of component 1
U.S. Geological Survey
Fraction of component 1. Column CV in spreadsheet.
Monte Carlo Results: Fraction error
Fraction error of component 1
U.S. Geological Survey
Fraction error of component 1. Column CW in spreadsheet.
Monte Carlo Results: Mean age, years
Mean age of second component in binary mixture
U.S. Geological Survey
Mean age of second component in binary mixture. Column CX in spreadsheet.
Monte Carlo Results: Mean age error, years
Mean age error of second component in binary mixture
U.S. Geological Survey
Mean age error of second component in binary mixture. Column CY in spreadsheet.
Monte Carlo Results: Model Parameter 1
PEM upper ratio, Dispersion parameter (DP), EPM ratio of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio of second component of binary mixture. Column CZ in spreadsheet.
Monte Carlo Results: Model Parameter 1 error
PEM upper ratio, Dispersion parameter (DP), EPM ratio error of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) upper ratio, Dispersion parameter (DP), EPM (exponential piston-flow model) ratio error of second component of binary mixture. Column DA in spreadsheet.
Monte Carlo Results: Model Parameter 2
PEM lower ratio, alpha parameter for FDM of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) of second component of binary mixture. Column DB in spreadsheet.
Monte Carlo Results: Model Parameter 2 error
PEM lower ratio, alpha parameter for FDM error of second component of binary mixture
U.S. Geological Survey
PEM (partial exponential model) lower ratio, alpha parameter for FDM (fractional dispersion model) error of second component of binary mixture. Column DC in spreadsheet.
Monte Carlo Tracer Results: 3H, in TU
Average simulated concentration of Monte Carlo simulations of tracer 1 (Tritium, in tritium units)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 1 (Tritium, in tritium units). Column DD in spreadsheet.
Monte Carlo Tracer Results: 3H, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 1
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 1. Column DE in spreadsheet.
Monte Carlo Tracer Results: 3He(trit), in TU
Average simulated concentration of Monte Carlo simulations of tracer 2 (Tritiogenic Helium-3, in tritium units)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 2 (Tritiogenic Helium-3, in tritium units). Column DF in spreadsheet.
Monte Carlo Tracer Results: 3He(trit), std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 2
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 2. Column DG in spreadsheet.
Monte Carlo Tracer Results: 3Ho, in TU
Average simulated concentration of Monte Carlo simulations of tracer 3 (Initial Tritium, in tritium units)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 3 (Initial Tritium, in tritium units). Column DH in spreadsheet.
Monte Carlo Tracer Results: 3Ho, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 3
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 3. Column DI in spreadsheet.
Monte Carlo Tracer Results: 3H/3Ho, ratio
Average simulated concentration of Monte Carlo simulations of tracer 4 (Tritium / Initial tritium ratio, unitless)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 4 (Tritium / Initial tritium ratio, unitless). Column DJ in spreadsheet.
Monte Carlo Tracer Results: 3H 3Ho, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 4
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 4. Column DK in spreadsheet.
Monte Carlo Tracer Results: SF6, in pptv
Average simulated concentration of Monte Carlo simulations of tracer 5 (Sulfur Hexafluoride, in parts per trillion by volume)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 5 (Sulfur Hexafluoride, in parts per trillion (10^-12) by volume). Column DL in spreadsheet.
Monte Carlo Tracer Results: SF6, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 5
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 5. Column DM in spreadsheet.
Monte Carlo Tracer Results: NO3-N, in mg/L as N
Average simulated concentration of Monte Carlo simulations of tracer 6 (Nitrate in recharge, milligrams per liter as nitrogen)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 6 (Nitrate in recharge, milligrams per liter as nitrogen). Column DN in spreadsheet.
Monte Carlo Tracer Results: NO3-N, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 6
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 6. Column DO in spreadsheet.
Monte Carlo Tracer Results: Tracer 7, empty
Average simulated concentration of Monte Carlo simulations of tracer 7
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 7. Column DP in spreadsheet.
Monte Carlo Tracer Results: Tracer 7, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 7
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 7. Column DQ in spreadsheet.
Monte Carlo Tracer Results: 14C, in pmC
Average simulated concentration of Monte Carlo simulations of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 8 (Carbon-14, in percent modern carbon--reconstructed 14C curve for last 50,000 yrs). Column DR in spreadsheet.
Monte Carlo Tracer Results: 14C, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 8
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 8. Column DS in spreadsheet.
Monte Carlo Tracer Results: 4He, cc@STP/gH2O
Average simulated concentration of Monte Carlo simulations of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP per gram of water)
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 9 (Radiogenic Helium-4, in cubic centimeters at STP (standard temperature and pressure) per gram of water). Column DT in spreadsheet.
Monte Carlo Tracer Results: 4He, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 9
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 9. Column DU in spreadsheet.
Monte Carlo Tracer Results: Tracer 10, empty
Average simulated concentration of Monte Carlo simulations of tracer 10
U.S. Geological Survey
Average simulated concentration of Monte Carlo simulations of tracer 10. Column DV in spreadsheet.
Monte Carlo Tracer Results: Tracer 10, std. err.
Standard error of simulated concentrations of Monte Carlo simulations of tracer 10
U.S. Geological Survey
Standard error of simulated concentrations of Monte Carlo simulations of tracer 10. Column DW in spreadsheet.
Tracer Input Variables: Tracer Name 1 through Tracer Name 10
Name(s) of tracer 1 through tracer 10
U.S. Geological Survey
Name(s) of tracer 1 through tracer 10. There are 10 individual columns. Columns DX-EG in spreadsheet.
Tracer Input Variables: Tracer Input Source 1 through Tracer Input Source 10
Name(s) of input data (row 4 of TracerInput worksheet) for tracer 1 through tracer 10
U.S. Geological Survey
Name(s) of input data (row 4 of TracerInput worksheet) for tracer 1 through tracer 10. There are 10 individual columns. Columns EH-EQ in spreadsheet.
Tracer Input Variables: Scaling Factor 1 through Scaling Factor 10
Scaling factor (row 17 of TracerInput worksheet) for tracer 1 through tracer 10
U.S. Geological Survey
Scaling factor (row 17 of TracerInput worksheet) for tracer 1 through tracer 10. There are 10 individual columns. Columns ER-FA in spreadsheet.
Tracer Input Variables: UZ travel time treatment 1 through UZ travel time treatment 10
Unsaturated zone trave time treatement (row 8,9 of TracerInput worksheet) for tracer 1 through tracer 10
U.S. Geological Survey
Unsaturated zone trave time treatement (row 8,9 of TracerInput worksheet) for tracer 1 through tracer 10. There are 10 individual columns. Columns FB-FK in spreadsheet.
Tracer Input Variables: Dissolved inorganic carbon 1
Dissolved inorganic carbon concentration for component 1
U.S. Geological Survey
Dissolved inorganic carbon concentration for component 1. Column FL in spreadsheet.
Tracer Input Variables: Dissolved inorganic carbon 2
Dissolved inorganic carbon concentration for component 2
U.S. Geological Survey
Dissolved inorganic carbon concentration for component 2. Column FM in spreadsheet.
Tracer Input Variables: Uranium, ppm
Uranium abundance in rocks or aquifer materials in parts per million
U.S. Geological Survey
Uranium abundance in rocks or aquifer materials in parts per million. Column FN in spreadsheet.
Tracer Input Variables: Thorium, ppm
Thorium abundance in rocks or aquifer materials in parts per million
U.S. Geological Survey
Thorium abundance in rocks or aquifer materials in parts per million. Column FO in spreadsheet.
Tracer Input Variables: Porosity
Porosity (volume of pore space / volume of aquifer materials)
U.S. Geological Survey
Porosity (volume of pore space / volume of aquifer materials). Column FP in spreadsheet.
Tracer Input Variables: Bulk Density
Bulk density of sediments
U.S. Geological Survey
Bulk density of sediments. Column FQ in spreadsheet.
Tracer Input Variables: Helium solution rate
Helium solution rate, in cc per g of water
U.S. Geological Survey
Helium solution rate, in cc (cubic centimeters) per g (gram) of water. Column FR in spreadsheet.
Tracer Input Variables: Time Increment
Time step increment of tracer input data (cell A12 of TracerInput worksheet)
U.S. Geological Survey
Time step increment of tracer input data (cell A12 of TracerInput worksheet). Column FS in spreadsheet.
TracerLPM is an interactive Excel® (2007 or later) workbook program for evaluating groundwater age distributions from environmental tracer data by using lumped parameter models (LPMs). Lumped parameter models are mathematical models of transport based on simplified aquifer geometry and flow configurations that account for effects of hydrodynamic dispersion or mixing within the aquifer, well bore, or discharge area. Five primary models are included in the workbook: piston-flow model (PFM), exponential mixing model (EMM), exponential piston-flow model (EPM), partial exponential model (PEM), and dispersion model (DM). Binary mixing models (BMM) can be created by combining primary models in various combinations. Travel time through the unsaturated zone can be included as an additional parameter. TracerLPM also allows users to enter age distributions determined from other methods, such as particle tracking results from numerical groundwater-flow models or from others not included in this program. Tracers of both young groundwater (anthropogenic atmospheric gases and isotopic substances indicating post-1940s recharge) and much older groundwater (carbon-14 and helium-4) can be interpreted simultaneously so that estimates of the groundwater age distribution for samples with a wide range of ages can be constrained.
TracerLPM is organized to permit a comprehensive interpretive approach consisting of hydrogeologic conceptualization, visual examination of data and models, and best-fit parameter estimation. Groundwater age distributions can be evaluated by comparing measured and modeled tracer concentrations in two ways: (1) multiple tracers analyzed simultaneously can be evaluated against each other for concordance with modeled concentrations (tracer-tracer application) or (2) tracer time-series data can be evaluated for concordance with modeled trends (tracer-time application). Groundwater-age estimates can also be obtained for samples with a single tracer measurement at one point in time; however, prior knowledge of an appropriate is required because the mean age is often non-unique.
LPM output concentrations depend on model parameters and sample date. All of thes have a parameter for mean age. The EPM, PEM, and DM have an additional parameter that characterizes the degree of age mixing in the sample. BMMs have a parameter for the fraction of the first component in the mixture. An together with its parameter values, provides a description of the age distribution or the fractional contribution of water for every age of recharge contained within a sample. For the PFM, the age distribution is a unit pulse at one distinct age. For the others, the age distribution can be much broader and span decades, centuries, millennia, or more. For a sample with a mixture of groundwater ages, the reported interpretation of tracer data includes the name, the mean age, and the values of any other independent model parameters.
TracerLPM also can be used for simulating the responses of wells, springs, streams, or other groundwater discharge receptors to nonpoint-source contaminants that are introduced in recharge, such as nitrate. This is done by combining an or user-defined age distribution with information on contaminant loading at the water table. Information on historic contaminant loading can be used to help evaluate a model’s ability to match real world conditions and understand observed contaminant trends, while information on future contaminant loading scenarios can be used to forecast potential contaminant trends.
Jurgens, B.C., Bohlke, J.K. and Eberts, S.M. (2012) TracerLPM (version 1): An Excel workbook for interpreting groundwater age distributions from environmental tracers, U.S. Geological Survey Techniques and Methods Report 4-F3, p. 60.
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