Groundwater age dating candidating ru
Uncertainty in age because of analytic uncertainty is approximately ± 0.5 years.
Larger uncertainties in age result from corrections in defining the tritiogenic H input has been relatively constant and therefore influenced to a lesser extent by hydrodynamic dispersion (Solomon and Sudicky 1991). Practical applications of environmental tracers to dating young ground water often depend on sampling from pre-existing domestic, industrial, and municipal-supply wells that, because of their construction, intercept relatively large open intervals and can produce mixed waters.
One liter of water with a concentration of 1 TU produces 7.2 disintegrations per minute(dpm) or 0.12 becquerel (Bq); one Bq corresponds to 1 disintegration per second (dps);one curie (Ci) is equal to 3.7x10 Bq.] Additional He sources, terrigenic He, may be present in aquifers where the rocks are enriched in U or Th, or in ground-water samples in which young water has mixed with relatively old water containing terrigenic He.
In these cases, the measured Ne content (assumed to be derived solely from the atmosphere) can be used to calculate the additional He (He has to be determined from the isotope measurements of tritium-free water in the aquifer under investigation.
In some mixtures, the CFC age of the young fraction could be determined from the ratio of two CFCs in the water sample, and mixing fractions based on the ratio of observed to expected CFC concentrations in the water sample (see Plummer and others, 2000). C., 1993, Age dating ground water by use of chlorofluorocarbons (CCl), and distribution of chlorofluorocarbons in the unsaturated zone, Snake River Plain aquifer, Idaho National Engineering Laboratory, Idaho: U. Geological Survey Water-Resources Investigations Report 93-4054, 47p.
If mixing of young and old water occurs, the CFC concentration in the ground-water sample must be divided by the fraction of young water in the mixture before age of the young fraction can be estimated.
G., 1993, Decrease in the growth rates of atmospheric chlorofluorocarbons 11 and 12: Nature, v.
N., and Busenberg, E., 1995, Chemical Evolution of groundwater near a sinkhole lake, northern Florida. Flow patterns, age of groundwater, and influence of lakewater leakage: Water Resources Research, v.
If the mixture contains multiple fractions of young water, the resulting age is regarded as a mean age of the young fraction(s) in the mixture. L., 1998a, Flow of river water into a karstic limestone aquifer-1. B., Busenberg, E., Drenkard, S., Schlosser, P., and Michel, R. Dating the young fraction in groundwater mixtures in the Upper Floridan aquifer near Valdosta, Georgia. Additionally, location of the mid-1960s bomb peak provides information on recharge rate (Schlosser and others, 1988, 1989; Solomon and Sudicky, 1991; Solomon and others, 1992, 1993; Ekwurzel and others, 1994). Locating the position of the mid-1960s bomb peak is difficult due to the required high density of vertical sampling and, therefore, is often an impractical means of obtaining ground-water age information. Ekwurzel, B., Schlosser, P., Smethie, Jr., Plummer, L. L., Weppernig, R., and, Stute, M., 1994, Dating of shallow groundwater: Comparison of the transient tracers Kr: Water Resources Research, v.