Tritium age dating groundwater

Isotopically enriched noble gases are inexpensive, commercially available, and non-toxic, allowing them to be used as introduced tracers to tag large volumes of recharging water.

The time it takes to travel to a given location, known as the groundwater age, can vary from days to thousands of years.

For relatively young groundwater, chlorofluorocarbons (CFCs) often are used.

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Uranium—lead dating method[ edit ] Main article: However, local eruptions of volcanoes or other events that give off large amounts of carbon dioxide can reduce local concentrations of carbon and give inaccurate dates.

Groundwater Ages Groundwater can either be very young, representing recent recharge to the subsurface, or it can exist as very old water that has been interacting with the rock and sediments that host it.

Chlorofluorocarbons (Freon) and tritium techniques are used to date groundwater that is less than 50 years old.

Theoretically, ages can be estimated by (1) the travel time of groundwater from the point of recharge to the subsurface point of interest as calculated by Darcy's law combined with an equation of continuity, (2) the decay of radionuclides which have entered the water from contact with the atmosphere, (3) the accumulation of products of radioactive reactions in the subsurface, (4) the degree of disequilibrium between radionuclides and their radioactive daughter products, (5) the time-dependent changes in the molecular structure of compounds dissolved in water, (6) the presence of man-made materials in groundwater, (7) the correlation of paleoclimatic indicators in the water with the known chronology of past climates, and (8) the presence or absence of ions which can be related to past geologic events that have been previously dated.

Environmental isotopes can be either radioactive or stable.

They can be used to determine the locations of groundwater recharge areas, circulation patterns in aquifers, sources of dissolved solids in groundwater, and the age of groundwater- the length of time it has been out of contact with the atmosphere.

SF 6 is another stable, human-made compound that has exhibited increasing concentrations in the atmosphere. Effect of mineral precipitation on isotopic composition and 14C dating of groundwater.

Unlike CFC concentrations, atmospheric SF 6 concentrations are expected to increase for the foreseeable future.

Various environmental isotopes and tracers are used to determine the age of groundwater.

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