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Regarding his development as an environmental scientist, Professor Stute says, "I knew early on that I wanted to dedicate my career to environmental issues and studied physics, because there was no such thing as environmental science to study at a university back then. My Ph D thesis research topic at the University of Heidelberg focused on novel tracer techniques to study the dynamics of ground water flow, and the use of ground water as an archive of paleoclimate.
Both observations and modeling suggest that 4He may be useful as a groundwater dating tool over a range of tens to hundreds of years. A model of 4He diffusion from spherical grains suggests that aquifer solids derived from old protoliths will release 4He at rates greater than supported by U/Th production for up to 50 million years in fine sands that have typical U/Th concentrations.Both observations and modeling suggest that 4He may be useful as a groundwater dating tool over a range of tens to hundreds of years.The apparent rate of 4He(rad) release is 130 μcm3 m-3 yr-1 and is 300 times greater than can be supported by the in situ decay of U and Th series nuclides (i.e., the 'steady state' approximation).Laboratory release experiments (conducted by sequentially heating the aquifer solids, measuring the amount of 4He released, and then extrapolating release rates to the in situ temperature) agree well with the field results and suggest that diffusion from aquifer solids is the source of 4He(rad).