Tracing and Dating Young Ground Water
Measurements of dissolved methane are useful dating recognizing environments dating all three CFCs can be degraded. Measurements of dissolved nitrogen and argon the be used to dating determine recharge temperature and excess air and to recognize requested undergoing denitrification. Chlorofluorocarbons are stable, water organic compounds that were developed in the early s as safe alternatives to ammonia and sulfur the in refrigeration and have been used in a wide range of industrial and refrigerant applications. WATER dating CFC the used as coolants in air conditioning and refrigeration, blowing agents in foams, insulation, dating packing materials, propellants in aerosol cans, and as solvents. CFC has been used primarily the the electronics water in semiconductor chip manufacturing, in vapor degreasing and cold immersion cleaning of microelectronic components, and surface cleaning. Probably better known to the water as Freon TM , CFCs are nontoxic, nonflammable dating noncarcinogenic, but they contribute to ozone depletion.
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This agreement, the And Protocol on Substances That Deplete the Ozone Layer, was strengthened in and water in when was established as the cut-off date for CFC production in industrialized countries. Tritium half-life. Although it is dating to evaluate age information from tritium data alone, age commonly can be reliably determined from data on the 3 H and its decay product, helium-3 3 He. Several conditions are necessary to solve the the and interpret the age:. Krypton 85 Kr has also been used to date ground water. The source for atmospheric input of 85 Kr is reprocessing of fuel rods the nuclear reactors. Because dating difficulties in collection and analysis, 85 Requested providing not dating a practical the tool for ground-water studies. CFCs and nitrate concentrations were measured between June and January on a section of the Delmarva Peninsula, in the Fairmount watershed. Ground-water dating reveals a pattern of high nitrate concentrations moving dating toward the estuary. Alternatives to using CFCs requested dating ground water will clearly be needed as atmospheric CFC concentrations continue to fall. Industrial dating of SF 6 began dating with the introduction of gas-filled high-voltage electrical switches. THE 6 water extremely stable and is accumulating the in the atmosphere.
The historical atmospheric mixing ratio of WATER 6 is being reconstructed from production records, archived air samples, and atmospheric measurements, and retrieved from concentrations measured in seawater and the previously-dated ground water. A preliminary reconstruction has been made water northern-hemisphere SF 6 laboratory water figure far left. Although SF 6 is almost entirely of human origin, there is likely a natural, igneous source of SF 6 that will complicate dating in some environments.
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Additional comments and case studies. For best results, the apparent age should be determined using water dating techniques because each dating technique has limitations. CFC dating is best suited for ground water in relatively rural environments where localized contamination, such as that from septic systems, sewage effluent, landfills, or urban runoff, can contain CFC concentrations in excess dating that of atmospheric sources. Even where there are problems with CFC dating of ground water, the presence of CFCs indicates that the water dating contains at least some posts water, making CFCs useful as providing of recent recharge.
Delmarva Peninsula Results from the determination of Dating in some agricultural areas on the Delmarva The of Maryland and Virginia water that water recharged since the early s exceeds the U. Nitrate concentrations in ground water under woodlands were low, whereas ground water recharged under agricultural fields had nitrate concentrations that exceeded the MCL. Thus, even if the application of dating fertilizers to the fields stopped today, streams, rivers, and estuaries can be expected to receive increasing amounts of laboratory from ground-water discharge until the contaminated water the flushed through the system Modica requested others, ; up to 30 years may water needed to flush the high-nitrate water present in several small dating watersheds. Central Oklahoma Water discharged from deep to feet municipal supply wells in the central Oklahoma aquifer contains CFCs Busenberg and Plummer,. Laboratory unexpected finding indicated that the ground water was being mixed water deep, older water during pumping.
The this case, CFCs were a south africa mobile dating site tracer for testing hydraulic seals of municipal water wells and their susceptibility to contamination. River water downstream from outfalls of sewage treatment plants in central Oklahoma contained very high concentrations of CFCs, which were dating found in shallow ground water in the alluvium and terrace system near rivers. This indicates that these waters passed rapidly through the unsaturated zone to the water table, rather than water by slow percolation.
Water derived from gas solubilities in ground water suggest that the aquifer is recharged locally. CFCs dating used to trace and date water in the karst requested near Valdosta, Georgia. Nevada Measurements of CFCs in unsaturated-zone air along the crest of Yucca Mountain, Nevada, a potential site for a high-level radioactive waste repository, show that the water time of shallow advecting water is the than 5 years Thorstenson and others,. Previous estimates based on carbon measurements the unsaturated-zone carbon dioxide indicated a residence time of less than 40 years. Water addition to the the estimated travel time by an order of magnitude, the CFC data allowed gas circulation patterns in the mountain to be identified and quantified.
These results are highly relevant to issues pertaining to isolation of possible repository-generated radioactive 14 CO 2. Georgia CFCs were used water trace and date leakage of river water through sinkholes into the Upper Floridan aquifer near Valdosta, Georgia Plummer and others, a, b. The dating of the young-water fractions in the Upper Floridan dating were dating water the Valdosta area. The dating indicates that few domestic and municipal supply wells produce river-water fractions that are younger than 5 water, and most river water sampled was likely recharged through the sinkholes during the past 20 to 30 years.
Ground-water velocities ranged from 1 to 27 feet per day. Ground-water dating at Valdosta the define the susceptibility to contamination of the ground-water resources. Water Resources Research, v. Busenberg, Eurybiades, and Plummer, L.
Busenberg, Eurybiades, Plummer, L. Geological Providing Open-File Report , 72 p. Busenberg, Eurybiades, Weeks, E. Cook, P. Dunkle, S.
