Dating groundwater Privat webcam
We find that the system is controlled by mixing of three distinct water masses: Interglacial or recent meteoric water (δ Kr ages range from 300 ka to 1.3 Ma for interglacial or recent meteoric water and glacial meltwater.
For the brine component, ages exceed the dating range of the ATTA-3 instrument of 1.3 Ma.
This increased reliance on the groundwater in concert with the strict regulation on water quality has led to a need by water managers and regulators to understand: Characterization of mean groundwater age and recharge temperature through the use of noble gas techniques provides information that is relevant to answering these questions and that is not accessible through traditional hydrogeologic approaches.
LLNL has developed a noble gas mass spectrometry facility that houses a state-of-the-art water-gas separation manifold and mass spectrometry system designed specifically for high throughput of groundwater samples. scientists with cutting-edge expertise in the measurement and interpretation of noble gases and tritium in groundwater.
When these individual fractionation factors (0.54 for the Pleistocene and 0.62 for the Judea Group) are used, it is revealed that both aquifers contain young water, in agreement with the Darcy calculation, which was recharged at the beginning of the period of thermonuclear atmospheric testing in the early 1960s.
The 1000-yr difference is an artifact of initial isotopic fractionation differences through the unsaturated zone as established elsewhere for these 2 aquifers.
The $^$Kr measurements are interpreted within this mixing framework to estimate the age of the end-members.
Deconvoluted $^$Kr ages range from 300 ka to 1.3 Ma for interglacial or recent meteoric water and glacial meltwater.
As additional recharge continues to enter the aquifer, older recharge is pushed deeper by the newer recharge, resulting in a trend of increasing groundwater age with depth.For the brine component, ages exceed the dating range of the ATTA 3 instrument of 1.3 Ma.The radiogenic noble gas components $^$He* and $^$Ar* are less conclusive but also support an age of 1 Ma for the brine. These aquifers have small storage capacities and good hydraulic properties. Radiocarbon and tritium determinations were carried out in 2 adjacent small aquifers in Israel.