The observations on the behavior of the noble gases in the hydrological cycle may provide the tools to calculate the initial noble-gas contents in recharging water. This is essential for: (a) the use of the noble gases as tracers in geothermal systems; and (b) the evaluation of initial noble-gas contents in ancient waters for paleotemperature studies. Noble-gas contents in four non-karstic and three karstic springs were repeatedly measured, along with the temperatures in the recharge and discharge points. The Ar, Kr, and Xe contents in non-karstic springs are found to reflect the temperature of the base of the aerated zone above the water table. This temperature is seen to be close to the local average annual temperature and different from the rainy season temperature. The difference between the temperature measured at a spring and the noble-gas-deduced temperature indicates the depth of circulation in the saturated aquifer and thus may enable one to recognize the recharge area (e.g., local rain or recharge from adjacent mountains). Karstic springs are found to contain substantial air excesses, revealing a negative correlation to discharge. These air excesses are attributed to air present in some parts of the karstic systems, more so in the low-discharge season than in the high one. This air is sucked in by the water when it rushes through narrow parts of the system. Excess air may provide a tracer for karstic waters. © 1979.
