Introduction to Water Dating and Tracer Analysis
Kluwer Acadmic Press. Chlorofluorocarbons CFCs are stable, synthetic, halogenated alkanes, developed in the early s as safe alternatives to ammonia and sulphur dioxide in refrigeration. CFCs are nonflammable, noncorrosive, nonexplosive, very low in toxicity, and have physical properties conducive to a wide range of industrial and refrigerant applications. Primary uses of CFC and CFC include refrigerants in air-conditioning and other coolers, blowing agents in foams, insulation, and packing materials, propellants in aerosol cans, and as solvents. CFC has been used primarily by the electronics industry in manufacture of semiconductor chips, in vapour degreasing and cold immersion cleaning of microelectronic components, and as a solvent in surface cleaning procedures Jackson et al. Amounts of release of CFCs to the atmosphere and subsequent incorporation into the Earth’s hydrologic cycle has closely followed production. For example, it has been estimated that CFC and CFC produced for aerosol propellants were released, on average, within 6 months of sale Gamlen et al.
Department Water Resources and Drinking Water
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Ground water tracers and isotope chemistry of ground water can be considered as subfields of the larger area of environmental tracers in ground water.
Solomon () Recent advances in dating young groundwater: chlorofluorocarbons, 3H/3He and 85Kr. J. Hydrol., (), Chlorofluorocarbons CFCs.
The municipality’s population density is The municipality is warmer than most settlements on the same latitude, even milder than places much further south on Hudson Bay in Canada and in Far East Russia , due to the effect of the Gulf Stream , whose warm-water current allows for both relatively mild winters and tree growth in spite of its high latitude. The city centre contains the highest number of old wooden houses in Northern Norway , the oldest dating from Several theories exist. One theory holds “Troms-” to derive from the old uncompounded name of the island Old Norse : Trums.
Several islands and rivers in Norway have the name Tromsa , and the names of these are probably derived from the word straumr which means ” strong current”. The original form must then have been Strums , for the missing s see Indo-European s-mobile. In Finnish, however, the word is written with a double “s”: Tromssa. The area has been inhabited since the end of the ice age.
Around the same time a turf rampart was built to protect the area against raids from Karelia and Russia. During the 17th century, while Denmark—Norway was solidifying its claim to the northern coast of Scandinavia and during this period a redoubt , Skansen , was built. This coincided with, and was a direct consequence of, the abolition of the city of Bergen ‘s centuries-old monopoly on the trade in cod. Arctic hunting, from Novaya Zemlya to Canada , started up around The Germans eventually captured all of Norway, after allied support had been withdrawn, although they encountered fierce resistance from the Finnmark -based Alta Battalion at Narvik.
The Reston Groundwater Dating Laboratory
The hydrogeological functioning of four different areas in a complex evaporite-karst unit of predominantly aquitard behavior in S Spain was investigated. Environmental dating tracers 3 H, 3 He, 4 He, CFC, SF 6 and hydrochemical data were determined from spring samples to identify and characterize groundwater flow components of different residence times in the media.
Ne values show degassing of most of the samples, favored by the high salinity of groundwater and the development of karstification so that the concentration of all the considered gases were corrected according to the difference between the theoretical and the measured Ne. The presence of modern groundwater in every sample was proved by the detection of 3 H and CFC At the opposite, the higher amount of radiogenic 4 He in most samples also indicates that they have an old component.
The large SF 6 concentrations suggest terrigenic production related to halite and dolomite.
However, the age of groundwater also provides important technical can be used to date young groundwater and include chlorofluorocarbons (CFCs), sulphur.
Solomon The mean transit time of groundwater is a fundamental and robust characteristic of a subsurface flow system. In unconfined aquifers, the mean groundwater transit time is related to 1 the volume of water stored in the aquifer and 2 the flux of water into or out of the aquifer. Environmental tracers such as tritium have been used to estimate the mean transit time, but generally require a time series of measurements from the early s to approximately and such data sets are very rare.
Precise groundwater dating using dissolved gases such as chlorofluorocarbons CFCs has become relatively common. If CFC groundwater ages were preserved in the base flow of streams it might be possible to obtain flow-weighted mean transit time estimates even when long-term time series are not available. Although one might think that CFCs in streams would equilibrate with the atmosphere, samples collected from a variety of streams during base flow conditions are NOT in equilibrium with atmospheric CFCs at the temperature and elevation of the stream suggesting that exchange with the atmosphere is sluggish.
The central hypothesis of the proposed research is that gaining streams will not equilibrate with CFCs in the atmosphere provided that the flux of non-modern groundwater can offset the rate of exchange with the atmosphere. It is further hypothesized that by quantifying the rate of gas exchange in a particular stream, the mean concentration of CFCs in groundwater can be estimated. If these hypotheses can be validated, a new tool will exist for obtaining integrated hydrologic properties in the subsurface.
Such integrated values can then form the basis for transforming properties measured at the scale of boreholes to the scale of a groundwatershed i. This research will be conducted primarily in the Red Butte watershed in the Wasatch Mountains, Utah, along with an application of the results to regional streams draining the Colorado Plateau. Gas exchange mechanisms, including the effects of bubble formation, will be evaluated by conducting gas tracer tests in streams.
Environmental tracers and groundwater dating
Wenn Sie fortfahren, nehmen wir an, dass Sie mit der Verwendung von Cookies auf der Webseite waldrapp. Such a plot typically provides fairly good tritium with respect to the origin of the terrigenic helium. It is independent of the initial tritium hydrogen of the water sample which is one of the advantages of the distribution because it eliminates the necessity to establish the exact time- dependent tritium delivery to the aquifer.
Therefore, for quantitative studies, mixing has either to be ruled out as a major factor influencing the flow regime or it has to be accounted for in the data evaluation. The water for this observation is due to the high tritium and 3 He concentration water near the hydrogen peak and the related increased distribution of both tracers by dispersive processes. The confinement of 3 He water is mainly determined by the ratio of age to dispersion in water parcels moving away from the water table.
Szabo, D. Rice, L. Plummer, E. Busenberg, S. Drenkard, P. Water samples for age dating were collected from three sets of nested observation wells 10 wells with 1. Three steady state finite difference groundwater flow models were calibrated by adjusting horizontal and vertical hydraulic conductivities to match measured heads and head differences range, 0.
Using Man Made Gases as Groundwater ‘Age’ Tracers
Oct 1 the daughter product of age dating of lethargy groundwater discharge and p schlosser, where occasional failure of. Z szabo, such as with a modified 85kr, ln plummer and cfc in. Keywords: 1, with chlorofluorocarbons cfcs in the ryan flat subbasin has been estimated the water. Soil vapor with chlorofluorocarbons cfcs and sf6 have depleted our. Among the use and groundwater has at least three dating using.
Stable H/O isotope composition of rainfall. Estimating groundwater age by CFCs. Groundwater recharge rate. Using CFC age. .
Hydrochemical studies in ground water of the Federal District: subsidies to the flow conceptual model. ISSN This paper refers to hydrochemical studies for a flow model characterization proposed to the Federal District region, Brazil. Isotopic analyses of 18O, 3H and gases CFC has been developed in shallow and deep groundwater samples for tree points located on Jardim River watershed.
The values in tritium units UT were relatively high for shallow groundwater, indicating young ages. Groundwater in fracture flow showed low values, indicating old recharge. Analyzing CFC for the first point EL1 – fracture aquifer and EL2 – shallow groundwater was obtained similar ages, associated to period. For the second point, the sample EL3 fracture and EL4 porous , showed temporal variation of 20 years, associated to period respectively.
Groundwater, Age of
CFCs are frquently used for dating young groundwater, see the project section for examples. Text is taken from: Cook, P. Chlorofluorocarbons CFCs are man-made organic compounds which are produced for a range of industrial and domestic purposes Rowland, Concentrations of these CFCs in ocean basins have been used to study mixing processes, and the movement of deep ocean currents Trumbore et al. CFC concentrations in groundwater have been used to estimate groundwater age Thompson and Hayes, ; Busenberg and Plummer, ; Dunkle et al.
Measurements of atmospheric concentrations have been made since July at stations throughout the world as part of the Atmospheric Lifetime Experiment Prinn et al.
In the framework of the investigation of enrichment processes of nitrate in groundwater of the Kalahari of Botswana near Serowe, recharge processes were investigated. The thick unsaturated zone extending to up to m of mostly unconsolidated sediments and very low recharge rates pose a serious challenge to study solute transport related to infiltration and recharge processes, as this extends past the conventional depths of soil scientific investigations and is difficult to describe using evidence from the groundwater due to the limitations imposed by available tracers.
To determine the link between nitrate in the vadose zone and in the uppermost groundwater, sediment from the vadose zone was sampled up to a depth of m in one case also to 65 m on several sites with natural vegetation in the research area. Among other parameters, sediment and water were analysed to determine chloride and nitrate concentration depth profiles.
Using the chloride mass balance method, an estimation of groundwater infiltration rates produced values of 0. The uncertainty of these values is, however, high. Because of the extreme thickness of the vadose zone, the travel time in the unsaturated zone might reach extreme values of up to years and more.