Tritium water dating

Helium: Samples are collected in special copper tubes fitted with stainless steel pinch-off clamps. F., 1988, Hydrogeologic Framework of the Virginia Coastal Plain: U. The discharge end of the tubes is fitted with an overpressure valve to prevent gas bubble formation in the ground-water sample Samples are collected in coated-glass bottles fitted with Teflon septum.

The results showed that the distance of the wells from the bank of the lake does not affect the calculated ages, especially for the deep wells where all deep wells have nearly the same age.

The shallow wells, which have ages nearly one year, have stable tritium of 11-12 TU, while the deep wells with ages nearly 24 years have stable tritium of 15-25 TU.

The potential for contaminants in ground water to degrade by chemical, biological, and physical processes along the ground-water pathway increases with the elapsed time between ground-water recharge and discharge.

Since aquifer type, as well as ground-water travel times, affects the transport and behavior of contaminants in ground water, the regionalization of apparent ages by hydrogeologic province can establish a basis for the determination of the susceptibility of ground water to near-surface contamination. D., and Fritz, Peter, 1997, Environmental isotopes in hydrogeology: New York, Lewis Publishers, 328 p. S., 1985, Quaternary paleoclimatology: Boston, Unwin Hyman, 472 p.

Sample water is filtered to eliminate contamination from particulates containing carbonate minerals.

Establishing a closed path from the water source minimizes contact with the atmosphere.

Atmospheric partial pressures of CFCs are determined by Henry's law from the recharge temperature estimated from dissolved gases in the sample (nitrogen/argon ratio) and measured concentrations of CFCs in the ground-water samples.

These calculated partial pressures are compared with the atmospheric mixing ratios of CFCs (fig.

Time and cost considerations prohibit a detailed assessment of each of the more than 4,000 public water supplies in Virginia.

Thus the VAS study proposes to characterize the susceptibility of all of the regional aquifers by studying a representative sample of water-supply wells.

Virginia's aquifers can be grouped into five categories based on the State's physiographic provinces: the Coastal Plain, Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateau (fig. Because ground-water flow and interaction with surface water are dependent on physiographic and climatic setting (Winter and others, 1998), the susceptibility to contamination of each of these regional aquifer systems must be evaluated individually. International Atomic Energy Agency (IAEA), 1981, Statistical treatment of environmental isotope data in precipitation: Vienna, IAEA, Technical Report Series No. Schlosser, Peter, 1992, Tritium/He dating of waters in natural systems, in Isotopes of noble gases as tracers in environmental studies: Vienna, IAEA, p.

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