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L. Knobel - United States Geological Survey
Association between atmospheric circulation patterns and firn-ice core records from the Inilchek glacierized area, central Tien Shan, Asia (Vladimir B. Aizen, Elena M. Aizen, John M. Melack, Karl J Kreutz, and L. DeWayne Cecil)
Glacioclimatological research in the central Tien Shan was performed in the summers of 1998 and 1999 on the South Inilchek Glacier at 5100-5460 m. A 14.36 m firn-ice core and snow samples were collected and used for stratigraphic, isotopic, and chemical analyses.The firn-ice core and snow records were related to snow pit measurements at an event scale and to meteorological data and synoptic indices of atmospheric circulation at annual and seasonal scales. Linear relationships between the seasonal air temperature and seasonal isotopic composition in accumulated precipitation were established. Changes in the d18O air temperature relationship, in major ion concentration and in the ratios between chemical species, were used to identify different sources of moisture and investigate changes in atmospheric circulation patterns. Precipitation over the central Tien Shan is characterized by the lowest ionic content among the Tien Shan glaciers and indicates its mainly marine origin. In seasons of minimum precipitation, autumn and winter, water vapor was derived from the arid and semiarid regions in central Eurasia and contributed annual maximal solute content to snow accumulation in Tien Shan. The lowest content of major ions was observed in spring and summer layers, which represent maximum seasonal accumulation when moisture originates over the Atlantic Ocean and Mediterranean and Black Seas.
Development of a Local Meteoric Water Line for southeastern Idaho, western Wyoming, and south-central Montana (Lyn Benjamin, LeRoy L. Knobel, L. Flint Hall, L. DeWayne Cecil, and Jaromy R. Green)
Linear regression analysis was applied to stable hydrogen (H) and oxygen (O) isotope data in 72 snow-core and precipitation samples collected during 1999-2001 to determine the Local Meteoric Water Line (LMWL) for southeastern Idaho, western Wyoming, and south-central Montana.
On the basis of (1) residuals from the regression model, (2) comparison of study-area deuterium-excess (d-excess) values with the global range of d-excess values, and (3) outlier analysis by means of Chauvenet's Criterion, values of four samples were excluded from final regression analysis of the dataset. Regression results for the 68 remaining samples yielded a LMWL defined by the equation d2H = 7.95 d18O + 8.09 (r2 = 0.98).
This equation will be useful as a reference point for future studies in this area that use stable isotopes of H and O to determine sources of ground-water recharge, to determine water-mineral exchange, to evaluate surface-water and ground-water interaction, and to analyze many other geochemical and hydrologic problems.
Earth paleoenvironments: Records preserved in mid- and low-latitude glaciers (L. DeWayne Cecil, Jaromy R. Green, and Lonnie G. Thompson)
The earth is in a state of constant physical, chemical, and biological change on a global scale. Global environmental alterations have occurred throughout the existence of the earth and will invariably happen in the next millennium and beyond. Global change can have immediate as well as future consequences that could affect all life on earth. As a result, the importance of understanding current and potential global environmental change has radically increased.
Numerous global environmental change studies are currently underway. From monitoring ongoing natural events such as earthquakes and volcanoes to delineating potential anthropogenic effects from industrial chemical fallout from the atmosphere, all studies focus on understanding the immediate and potential environmental change and monetary impacts associated with such events. The study of global environmental change caused by anthropogenic influences requires knowing how and when the influences occurred and what effects the environment will suffer. Once these are known, the resultant future climactic and environmental changes can be projected. Additionally, studies of natural climactic and environmental alterations require the knowledge of long-term historical changes in order to predict or understand future shifts. Knowledge of past changes can only be acquired by studying and analyzing preserved environmental records that act as archives of these changes.
Preserved archives of past climactic and environmental conditions do exist in nature. For example, glaciers, ice caps, and ice sheets around the world can be repositories of climactic and environmental change. Ice cores from the polar regions have provided the scientific community with an unprecedented picture of past environmental change through chemical, isotopic, and stratigraphic data. High-resolution ice core records have also been obtained from high altitude sites in the tropics. However, weather patterns and climate changes affect high-latitude regions of the world differently than mid- to low-latitude areas. In addition, the majority of the world's population, at least 85 percent, lives between 50o N and 50o S. Therefore, understanding potential environmental change in mid- and low-latitude regions is of prime importance and could be accomplished by utilizing ice cores collected from selected alpine areas.
Research on temperate ice cores faces the challenge of several commonly held beliefs about ice cores in "warm" environments. First, that the influence of meltwater percolation - which tends to smooth glaciochemical variations in the glacier forming firn and snow- precludes the use of isotopic and chemical tracers. Second, that the high accumulation rates typical for temperate glaciers and ice sheets limit the length of the record to at most, a few centuries. Third, that the availability of other climate proxies, such as pollen and tree-ring records, makes temperate ice cores unnecessary.
Research at several mid-latitude sites worldwide has shown that these common beliefs are not warranted. Glacial research has already proven that ice cores collected from mid-latitude glaciers preserve the isotopic record with surprising accuracy and, for some glaciers, represents thousands of years of record. In addition, ice cores archive not only natural variations in climate and the environment but anthropogenic influences introduced over the last two centuries as well. Such additional anthropogenic information can aid in distinguishing between natural and human additions to the environment and thus further refine the understanding of future global, environmental, and climate change.
There is now a small army of diverse researchers worldwide turning to the archived environmental record in mid- and low-latitude ice cores to answer diverse questions from natural and anthropogenic influences on climate change to rates of glacial retardation and growth. With the advent of ultra-sensitive analytical methods such as accelerator mass spectrometry and the experiences of diverse research teams, glaciers worldwide, with their environmental records and markers locked in, are becoming accessible.
These new scientific tools and their application to understanding our influence on global environmental processes are the focus of this book. In the field of glacial research and the associated global impacts on humans there is no set of handy formulas into which various parameters can be substituted to obtain answers for the complex problems facing the world's population. This book was designed with that fact in mind.
The papers collected here represent some of the leading research and methods development in the growing scientific field of documenting global climactic and environmental changes using records archived at mid- and low-latitude sites; historically, presently, and in the future. It is hoped that current researchers and students will find the introductory "how-to" methods section useful in their work. Additionally, with a good solid grounding in the methods utilized in bringing ice core records from remote, harsh environments to the laboratory for analyses and interpretation, students will be prepared to appreciate the significance of any glacial research they may find in the literature.
L. DeWayne Cecil
U.S. Geological Survey
Idaho Falls, Idaho U.S.A.
Development of an AMS method to study oceanic circulation characteristics using cosmogenic 39Ar (Ph. Collon, M. Bichler, J. Caggiano, L. DeWayne Cecil, Y. El Masri, R. Golser, C.L. Jiang, A. Heinz, D. Henderson, W. Kutschera, B.E. Lehmann, P. Leleux, H.H. Loosli, R.C. Pardo, M. Paul, K.E. Rehm, P. Schlosser, R.H. Scott, W.M. Smethie, Jr. and R. Vondrasek)
Initial experiments at the ATLAS facility resulted in a clear detection of cosmogenic 39Ar signal at the natural level. The present paper summarizes the recent developments of 39Ar AMS measurements at ATLAS: the use of an electron cyclotron resonance (ECR) positive ion source equipped with a special quartz liner to reduce 39K background, the development of a gas handling system for small volume argon samples, the acceleration of 39Ar8+ ions to 232 MeV, and the final separation of 39Ar from 39K in a gas-filled spectrograph. The first successful AMS measurements of 39Ar in ocean water samples from the Southern Atlantic ventilation experiment (SAVE) are reported.
Methods of Mid- and Low-Latitude Glacial Record Collection, Analysis, and Interpretation (Jaromy R. Green, L. DeWayne Cecil, and Shaun K. Frape)
The credibility of collecting, analyzing, interpreting and "dating" mid- and low-latitude glacial ice samples depends primarily on the methods used. Due to the wide variety of characteristics among mid- and low-latitude glaciers (such as location, altitude, precipitation, size, movement, and archived history), the methods used to study such glaciers vary from site to site and must be chosen with care. Of benefit to many of today's researchers is the ability to build upon the knowledge of past studies of mid- and low-latitude glaciers. In the 1970s and 80s, research was performed on such places as the Quelccaya Ice Cap in the Andes mountains of Peru, the Dunde Ice Cap within the Tibetan Plateau, and the Colle Gnifetti in the Alps. Past and present studies of these glacial sites allow current day researchers to more correctly identify and use those methods that are logistically, scientifically, and statistically sound to research additional mid- and low-latitude glacial sites. The following chapter details some of the methods used in current research.
A high resolution record of chlorine-36 nuclear-weapons-tests fallout from central Asia (J.R. Green, L.D. Cecil, H.-A. Synal, J. Santos, K.J. Kreutz, and C.P. Wake)
The Inilchek Glacier, located in the Tien Shan Mountains, central Asia, is unique among mid-latitude glaciers because of its relatively large average annual accumulation. In July 2000, two ice cores of 162 and 167 meters (m) in length were collected from the Inilchek Glacier for chlorine-36 (36Cl) analysis as part of a collaborative international effort to study the environmental changes archived in mid-latitude glaciers worldwide. The average annual precipitation at the collection site was calculated to be 1.6 m. In contrast, the reported average annual accumulations at the high-latitude Dye-3 glacial site, Greenland, the mid-latitude Guliya Ice Cap, China, and the mid-latitude Upper Freemont Glacier, Wyoming, USA, were 0.52, 0.16, and 0.76 m, respectively. The resolution of the 36Cl record in one of the Inilchek ice cores was from 2 to 10 times higher than the resolution of the records at these other sites and could provide an opportunity for detailed study of environmental changes that have occurred over the last 150 years.
Despite the differences in accumulation among these various glacial sites, the 36Cl profile and peak concentrations for the Inilchek ice core were remarkably similar in shape and magnitude to those for ice cores from these other sites. The 36Cl peak concentration from 1958, the year during the mid-1900s nuclear-weapons-tests period when 36Cl fallout was largest, was preserved in the Inilchek core at a depth of 90.56 m below the surface of the glacier (74.14-m-depth water equivalent) at a concentration of 7.7 x 105 atoms of 36Cl/gram (g) of ice. Peak 36Cl concentrations from Dye-3, Guliya, and the Upper Freemont glacial sites were 7.1 x 105, 5.4 x 105, and 0.7 x 105 atoms of 36Cl/g of ice, respectively. Measurements of 36Cl preserved in ice cores improve estimates of historical worldwide atmospheric deposition of this isotope and allow the sources of 36Cl in ground water to be better identified.
Event to decadal-scale glaciochemical variability on the Inilchek Glacier, Central Tien Shan (Karl J. Kreutz, Cameron P. Wake, Vladimir B. Aizen, L. DeWayne Cecil, Jaromy R. Green, and Hans-Arno Synal)
Glaciochemical records developed from mid- and low-latitude Asian ice cores provide a unique archive of past atmospheric conditions, and can be used for high-resolution reconstructions of climactic and environmental variability. To realize the full potential of chemical signals preserved in ice cores, detailed modern proxy calibration studies must be undertaken to understand the effects of local deposition noise and the relationships between meteorological conditions and time-series chemical variability. Previous work in the Tien Shan mountains of Central Asia has demonstrated the usefulness of stable water isotopes and soluble ions for investigating temperature, moisture flux, atmospheric circulation, and dust loading on different timescales. On a seasonal basis, a good correlation between d18O ratios and site temperature has previously been demonstrated. Alternatively, a 1996 worker interpreted fresh snow event isotope data in terms of moisture source and transport pathway. For soluble ions, the strong influence of dust derived from surrounding arid regions has been noted in snow, firn core, and aerosol studies. Here we present new fresh snow and snowpit results from the Inilchek Glacier, Central Tien Shan collected during July/August 2000. During the 2000 field season, two deep ice cores were also recovered, and are being used to develop high-resolution stable isotope and soluble ion records of the past 200-500 years. Our goal in this chapter is to assess local-scale spatial chemical variability in the Inilchek basin and the relation between time series chemical variability and regional meteorological parameters. Such knowledge is critical for the proper interpretation of high-resolution records developed from deep ice cores, particularly at sites such as the Inilchek where relatively high accumulation rates may allow reconstructions on seasonal or sub-seasonal timescales.
Variations between d18O in recently deposited snow and on-site air temperature, Upper Fremont Glacier, Wyoming (David L. Naftz, David D. Susong, L. DeWayne Cecil, and Paul F. Schuster)
Oxygen isotopic ratios (d18O) in ice
cores have been used extensively to reconstruct past climate trends. Recent
investigations have documented positive correlations between site-specific d18O
values in snow and ice to on-site average air temperature (TA) during snow
accumulation events in polar regions.
To date (2003), only limited observations link the d18O values in ice and snow samples to on-site air temperature at high-altitude, mid- and low-latitude ice-coring sites. In 2002, our team developed a series of site-specific transfer functions between on-site air temperature and d18O values in snow deposited at a mid-latitude ice coring site established at over 4,000 m above sea level (masl) on Upper Fremont Glacier (UFG), Wyoming. The site-specific transfer functions developed from this site were used in conjunction with d18O values from ice cores obtained from UFG to reconstruct changes in air temperature since the early 1700s.
Because UFG is a remote, high-altitude site, it is not possible to physically collect discrete snow samples from individual storm events for d18O analysis. Instead, the site was visited one to three times per year and snow pits were excavated and used to sample the accumulated snowpack. The timing and amount of each snow accumulation event in the excavated snow pits on UFG was determined from snow pillow data from Cold Springs SNOTEL site, approximately 22 km northeast from UFG, and used in the development of site-specific transfer functions. This method of determining the timing and relative amounts of accumulation events on UFG relied on the following assumptions: (1) snow redeposition from wind events and melting was minimal after each accumulation event; (2) the same storms impact both sites with the same relative intensities; and (3) all precipitation on the UFG is in the form of snow and, therefore, accumulates and can be used as a proxy for cumulative precipitation. None of these assumptions were valid 100 percent of the time.
To better record the on-site snow accumulation and redeposition on UFG during 1999-2000, an hourly record of snow depth was obtained using an ultrasonic sensor. Instead of relying on the SNOTEL data as a proxy record for snow accumulation on UFG, on-site data were possible. The objectives of this chapter are to: (1) investigate and model the transfer function between d18O values in snow and the corresponding air temperature using the continuous, on-site snow-depth and air temperature monitoring equipment installed on UFG; (2) compare the transfer function developed from the on-site snow-depth sensor to transfer functions developed using off-site snow accumulation data; and (3) reconstruct and compare air temperatures from d18O values in UFG ice cores using both transfer functions.
Hydraulic and geochemical framework of the Idaho National Engineering and Environmental Laboratory vadose zone (John R. Nimmo, Joseph P. Rousseau, Kim S. Perkins, Kenneth G. Stollenwerk, Pierre D. Glynn, Roy C. Bartholomay, and LeRoy L. Knobel)
Questions of major importance for subsurface contaminant transport at the Idaho National Engineering and Environmental Laboratory (INEEL) include (i) travel times to the aquifer, both average or typical values and the range of values to be expected, and (ii) modes of contaminant transport, especially sorption processes. The hydraulic and geochemical framework within which these questions are addressed is dominated by extreme heterogeneity in a vadose zone and aquifer consisting of interbedded basalts and sediments. Hydraulically, major issues include diverse possible types of flow pathways, extreme anisotropy, preferential flow, combined vertical and horizontal flow, and temporary saturation or perching. Geochemically, major issues include contaminant mobility as influenced by redox conditions, the concentration of organic and inorganic complexing solutes and other local variables, the interaction with infiltrating waters and with the contaminant source environment, and the aqueous speciation of contaminants such as actinides. Another major issue is the possibility of colloid transport, which inverts some of the traditional concepts of mobility, as sorbed contaminants on mobile colloids may be transported with ease compared with contaminants that are not sorbed. With respect to the goal of minimizing aquifer concentrations of contaminants, some characteristics of the vadose zone are essentially completely favorable. Examples include the great thickness (200 m) of the vadose zone, and the presence of substantial quantities of fine sediments that can retard contaminant transport both hydraulically and chemically. Most characteristics, however, have both favorable and unfavorable aspects. For example, preferential flow, as promoted by several notable features of the vadose zone at the INEEL, can provide fast, minimally sorbing pathways for contaminants to reach the aquifer easily, but it also leads to a wide dispersal of contaminants in a large volume of subsurface material, thus increasing the opportunity for dilution and sorption.
Radiochemical and Chemical Constituents in Water from Selected Wells and Springs from the Southern Boundary of the Idaho National Engineering and Environmental Laboratory to the Hagerman Area, Idaho, 2002 (Gordon W. Rattray and Linford J. Campbell)
The U.S. Geological Survey, Idaho Department of Water Resources, and the State of Idaho INEEL Oversight Program, in cooperation with the U.S. Department of Energy, sampled water from 17 sites as part of the sixth round of a long-term project to monitor water quality of the eastern Snake River Plain aquifer from the southern boundary of the Idaho National Engineering and Environmental Laboratory to the Hagerman area. The samples were collected from eight irrigation wells, three domestic wells, one stock well, one dairy well, one commercial well, one observation well, and two springs and analyzed for selected radiochemical and chemical constituents. One quality-assurance sample, a sequential replicate, also was collected and analyzed.
Many of the radionuclide and inorganic-constituent concentrations were greater than the reporting levels and most of the organic-constituent concentrations were less than the reporting levels. However, none of the reported radiochemical- or chemical-constituent concentrations exceeded the maximum contaminant levels for drinking water established by the U.S. Environmental Protection Agency. Statistical evaluation of the replicate sample pair indicated that, with 95 percent confidence, 132 of the 135 constituent concentrations of the replicate pair were equivalent.
Evidence of Abrupt Climate Change and the Development of an Historic Mercury Deposition Record Using Chronological Refinement of Ice Cores at Upper Fremont Glacier (Paul F. Schuster, David L. Naftz, L. DeWayne Cecil , and Jaromy R. Green)
Paleoclimatic and paleoenvironmental ice-core records are not common from mid-latitude locations in the contiguous U.S.A. Although excellent paleo-records exist for the high latitudes, ice-core records from polar regions may be considered proxy indicators of climactic and environmental change in the mid latitudes. Unlike polar ice cores which are more likely to preserve visual, chemical and isotopic stratigraphy with sub-annual resolution, visual stratigraphy and sub annual isotopic resolution are generally not apparent in mid-latitude ice cores. In addition, meltwater percolation can influence chemical and isotopic stratigraphy of alpine glaciers from mid-latitude ice cores by "damping" the environmental signal. Despite these problems, through chemical lines of evidence, several investigators indicated that the Upper Fremont Glacier (UFG) in the Wind River Range, Wyoming, U.S.A., (43° 07' 37" N, 109° 36' 54" W) is suitable for reconstruction of isotopic and chemical paleoclimate and environmental change records.
For a temperate glacier, the UFG has a combination of qualifications conducive to preserving paleoenvironmental signals. The drill-site elevation is 4100 m. Minimum, maximum and average annual air temperatures during 5 years of record were -36°C, 13°C, and -7°C respectively. Temperature profiles from snow pits, conducted on an intermittent basis on the UFG, indicated that the snow pack was typically isothermal at 0°C during the summer months. During the winter months, the snow pack was below 0°C, ranging from -7°C to -2°C. The net accumulation rate is 96 cm snow weq/yr, based on the vertical position of the 1963 tritium (3H) fallout record. The glacial surface gradient is nearly level, reducing crevassing and fracturing of the ice strata. These characteristics reduce the potential for meltwater to alter any paleoenvironmental signal. Because the remoteness of the site limits the influence of local sources of atmospheric mercury (Hg) deposition to the UFG, the location is favorable for measuring historical regional and global deposition of Hg and other chemical constituents from the atmosphere.
A grasshopper leg was recovered in 1991 near the base (152-m depth) of the UFG which yielded a carbon-14 (14C) age of 221 ± 95 years before present. Based on present-day accumulation and ablation rates, ice deposited near the bottom of the glacier formed from snow which fell between about A.D. 1716 and 1820. This chronology, albeit informative, did not provide the accuracy needed to date abrupt climate change or interpret paleoenvironmental signals on, at least, a decadal time scale during the last 270 years.
Further study, direct current electrical conductivity measurements (ECM), scanning electron microscopy (SEM), and energy dispersion analysis (EDA) were performed, Hg concentrations were measured, and isotopic and chemical data were reexamined to: (1) identify volcanic fallout in the ice cores from historical volcanic eruptions, (2) support and refine previous low-resolution chronological estimates of the UFG ice cores, (3) constrain the time of the Little Ice Age (LIA) transition in alpine regions of Central North America, and (4) reconstruct an historical record of atmospheric Hg deposition. The results discussed here will, hopefully, increase awareness and urgency of recovering ice cores from mid-latitude alpine glaciers for paleoclimate studies before these records disappear or are severely compromised by meltwater effects in response to a warming climate. With the addition of the ECM and the Hg data, the UFG ice core data set is the most extensive of its kind from a glacier in the contiguous U.S.
To underscore the urgency to recover these unique records, increasing global temperatures are threatening the existence and integrity of mid- and low-latitude glaciers, which are receding rapidly. Thus, any future research involving mid-latitude glaciers must be prompt. Key to the advancement of understanding environmental change on a global scale through the interpretation of mid-latitude ice-core data is the establishment of global linkage with ice cores from other regions of the world. If recession continues at these rates, the Dinwoody Glacier, about 3 kilometers north of the UFG, will be gone in about 20 years. Other estimates indicate that the remaining glaciers in Glacier National Park, Montana will no longer exist in 50 to 70 years and high alpine glaciers in the Andes of South America (i.e. Quelccaya) will be severely compromised by meltwater processes. These irreplaceable paleoenvironmental resources may literally melt away in the near future releasing an additional and potentially large reservoir of Hg and other contaminants trapped in snow and ice to the environment.
Aizen, V. B., Aizen, E. M., Melack, J. M., Kreutz, K. J., and Cecil, L. D., 2004, “Association between atmospheric circulation patterns and firn-ice core records from the Inilchek glacierized area, central Tien Shan,” Asia: Journal of Geophysical Research, v. 109, D08304, p. 1-18.
Benjamin, Lyn, Knobel, L. L., Hall, L. F., Cecil, L. D., and Green, J. R., 2004, “Development of a Local Meteoric Water Line for southeastern Idaho, western Wyoming, and south-central Montana”: U.S. Geological Survey Scientific Investigations Report 2004-5126, 17 p.
Cecil, L. D., Green, J. R., and Thompson, L. G., editors, 2004, “Earth paleoenvironments: Records preserved in mid- and low-latitude glaciers in Developments in paleoenvironmental research 9”: Kluwer Academic Publishers, The Netherlands, 249 p.
Collon, Ph., Bichler, M., Caggiano, J., Cecil, L. D. El Masri, Y., Golser, R., Jiang, C. L., Heinz, A., Henderson, D., Kutschera, W., Lehmann, B. E., Leleux, P., Loosli, H. H., Pardo, R. C., Paul, M., Rehm, K. E., Schlosser, P., Scott, R. H., Smethie, W. M., Jr., and Vondrasek, R., 2004, “Development of an AMS method to study oceanic circulation characteristics using cosmogenic 39Ar: Nuclear Instruments and Methods in Physics Research”, B223-224, p. 428-434.
Green, J. R., Cecil, L. D., and Frape S. K., 2004, “Methods of Mid- and Low-Latitude Glacial Record Collection, Analysis, and Interpretation: chapter in Earth paleoenvironments: Records preserved in mid- and low-latitude glaciers”, Cecil, L. D., Green, J. R., and Thompson, L. G., editors, Kluwer Academic Publishers, The Netherlands, 249 p.
Green, J. R, Cecil, L. D, Synal, H. A., Santos, J., Kreutz, K. J., and Wake, C. P., 2004, “A high resolution record of chlorine-36 nuclear-weapons-tests fallout from central Asia”: Nuclear Instruments and Methods in Physics Research, B223-224, p. 854-857.
Kreutz, K. J., Wake, C. P., Aizen, V. B., Cecil, L. D., Green, J. R., and Synal, H. A., 2004, “Event to decadal-scale glaciochemical variability on the Inilchek Glacier, Central Tien Shan: chapter in Earth paleoenvironments: Records preserved in mid- and low-latitude glaciers Cecil, L. D., Green, J. R., and Thompson, L. G., editors, Kluwer Academic Publishers, The Netherlands,
Naftz, D. L., Susong, D. D., Cecil, L. D., and Schuster, P. F., 2004, “Variations between d18O in recently deposited snow and on-site air temperature, Upper Fremont Glacier, Wyoming”: chapter in Earth paleoenvironments: Records preserved in mid- and low-latitude glaciers Cecil, L.D., Green, J.R., and Thompson, L.G., editors, Kluwer Academic Publishers, The Netherlands, 249 p.
Environmental Protection Agency (EPA), 2002, "National Primary Drinking Water Regulations," Code of Federal Regulations, 40 CFR 141, Office of the Federal Register.
IDAPA 58.01.11, "Ground Water Quality Rules," State of Idaho Department of Health and Welfare, current revision.
U.S. Department of Energy (DOE) Order 5400.5, 1993, "Radiation Protection of the Public and the Environment," U.S. Department of Energy, January 7.
U.S. Department of Energy, 1988a, Internal Dose Conversion Factors for Calculation of Dose to the Public, DOE/EH-0071, July.
U.S. Department of Energy, 1988b, External Dose
Conversion Factors for Calculation of Dose to the Public, DOE/EH-0070, July.
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