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. For investigations using groundwater, we applied the chlorofluorocarbons CFC, CFC, sulphur hexafluoride SF 6 and tritium to identify potential recharge, and found indications for some advective transport of the CFCs and SF 6 , which we accounted for as constituting potential active localised recharge.
The Reston Groundwater Dating Laboratory
Plummer, E. Busenberg, S. Drenkard, P. Schlosser , B. Ekwurzel, R. Weppernig, J.
the high velocity of groundwater circulation in Japan (Asai and Tsujimura, ), SF6 may be a more useful tracer than. CFCs in dating young groundwater.
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.
Department Water Resources and Drinking Water
Numeriska experiment gjordes med en modell av en jord—bergprofil. Knowledge about the groundwater recharge is essential for the prediction of impacts of groundwater withdrawal and underground construction. Recharge in the bedrock is, however, difficult to estimate. The objectives of this thesis were to increase the understanding of groundwater recharge in crystalline bedrock, to investigate how the recharge could be estimated, and to develop new models to describe the recharge.
The study was based on three approaches: groundwater dating using chlorofluorocarbons CFCs , geohydraulic field measurements, and mathematical modelling.
Unfortunately, CFCs catalyze reactions in the stratosphere that deplete atmospheric ozone. This resulted in international agreements to limit global CFC.
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. Particularly, GA 50 is derived from the median groundwater age and is presented as a new way of interpreting mixed groundwater age data. A greater fraction of old groundwater 3 H and CFC free was identified in discharge areas, while the proportion and estimated infiltration date of the younger fractions in recharge areas were higher and more recent, respectively.
The application of different approaches has been useful to corroborate previous theoretical conceptual model proposed for the study area and to test the applicability of the used environmental tracer in dating brine groundwater and karst springs. Andreo, M. Mudarra The hydrogeological functioning of four different areas in a complex evaporite-karst unit of predominantly aquitard behavior in S Spain was investigated.
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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.
Linking chloride mass balance infiltration rates with chlorofluorocarbon and SF6 groundwater dating in semi-arid settings: potential and limitations. Isotopes.
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. Environmental tracers are simply chemical or isotopic solutes that are found in ground water as a result of ambient conditions rather than the deliberate activity of a researcher.
They are studied mainly for the information they give about the ground water flow regime rather than the nature of the chemical activity in the ground water system. Such tracers have assumed new prominence in the past decade as a result of the refocusing of attention in applied ground water hydrology from questions of ground water supply, which are somewhat independent of the details of the flow path, to questions of ground water contamination, for which understanding the flow path and the nature of solute transport along it are central.
Opportunities in the Hydrologic Sciences NRC, emphasizes that “environmental isotopes are a key tool in studying the subsurface component of the hydrologic cycle. Despite recently increased interest in applications of environmental tracers, no clear path of development over the past 5 to 10 years can be laid out. This diffuse and unpredictable nature of development is a direct outcome of the opportunistic nature of the field.
Scientific disciplines that have a large theoretical component e. New developments are driven in large part by intellectual assessment of immedi-. In contrast, the application of environmental tracers to ground water hydrology has tended to be driven in large part by the introduction of analytical technologies developed by workers in other fields. Although in some cases the systematics of the tracer behavior have been worked out during investigations of ground water systems, more commonly the systematics have been previously well understood from independent investigations and the focus has mainly been on what the tracers can reveal about ground water flow and transport.
Using Man Made Gases as Groundwater ‘Age’ Tracers
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.
Many aspects of the subject of dating young groundwater appear in Cook and Herczeg (), and in “Guidebook on the Use of Chlorofluorocarbons in.
Toggle navigation ScienceBase-Catalog. Your browser does not have support for cookies enabled. Some features of this application will not work. Year The analytical procedure determines concentrations of the four tracers in air and water samples. SF5CF3 and CFC can be used to date groundwaters in some environments where the CFCs and SF6 have previously failed because these new tracers have increasing atmospheric input functions, no known terrigenic source, and are believed to be stable under reducing conditions.
SF5CF3 has a dating range from to modern; the mixing ratio mole fraction in North American air has increased from the detection limit of 0. No evidence was found for degradation of SF5CF3 in laboratory anaerobic systems. CFC is a trace atmospheric gas with a dating range in groundwater of about to modern. CFC has been used primarily in very low-temperature refrigeration; thus groundwater environments are less likely to be contaminated with nonatmospheric sources as compared to other widely used CFCs.
The new dating procedure was tested in water samples from wells and springs from Maryland, Virginia, and West Virginia. Item Actions View Item as Save Item as
Groundwater, Age of
Nitrogen pollution of freshwater and estuarine environments is one of the most urgent environmental crises. Shallow aquifers with predominantly local flow circulation are particularly vulnerable to agricultural contaminants. Water transit time and flow path are key controls on catchment nitrogen retention and removal capacity, but the relative importance of hydrogeological and topographical factors in determining these parameters is still uncertain.
We used groundwater dating and numerical modeling techniques to assess transit time and flow path in an unconfined aquifer in Brittany, France. The
Stable H/O isotope composition of rainfall. Estimating groundwater age by CFCs. Groundwater recharge rate. Using CFC age. .
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.
Prescription drug pollution: a wide range of cfc method. The cfc ‘ratio age’ dating methods chlorofluorocarbons. Alternative tools for dating methods chlorofluorocarbons cfcs are typically invoked: 1, which was compared with an example of the. The rain that report on henry’s law solubility. An area percolates trickles down through soil air between the difference in.