A. SUCKOW and C. SONNTAG (1993) found that salt have influence on the noble gas thermometer: "The negative noble gas temperatures can be explained by a loss of noble gases from the highly saline aquifer: since salt drastically reduces the noble gas solubilities, the brines are supersaturated with respect to the noble gases. This supersaturation is the driving force enriching the low permeability layer above the brines with noble gases and causing apparent negative NGTs." It was found in a deep (100-200 m below ground, confined for the middle layer) aquifer above a salt dome. And they explained this kind of degassing with a gradient of partial pressure that driving the diffusion process. NGTs were shown with figures but not detailed data of solubilities or concentrations.

Well,

Studies of the distribution of helium concentrations in groundwater systems

Helium-rich groundwater, as a general rule, was found in confined systems deep below sea level, a observation that in itself indicates that one deals with stagnant systems. The concentration of helium in water saturated with air is at most 5 x 10-8 cc STP / cc water, ie an increase above this concentration is of non-atmospheric origin. In the terrain on stable parts of the Earth's crust, the only source of helium is non atmospheric origin. However, together with tectonic plate margins and in volcanic systems, helium is added to groundwater, contributions of helium to the mantle are marked by an increase of 3H: 4He and rarely reach 50% of helium observed.

Regards

Dear Bayan Hussien ,

Many thanks for your attention and kind reply.

Yes, the max concentration for helium is at the situation of temperature (T)=0 degree C, pressure (P)=1 atm, and water salinity (S)=0.

If there was only atmospheric noble gas in groundwater, would the concentration change due to changed T, P or/and S in a closed system? I want to know that if the inert noble gas concentration stay unchanged from the recharge area (after equilibrium) to the discharge area or sampling area? It seems like that the Henry's Law only care about the air-water exchange process. I am not sure whether I understand it correctly.

Thanks again for your answers.

Kind regards

Dan

Well, for example

Example: In the Milo Holdings 3 well, 1421 m deep, in the Jurassic rock sequence east Australia, the helium concentration of 1000 x10-8 cc STP /cc water was found. The following local parametric values were applied to calculate the water age: ζHe = 1; U = 1.7 ppm; Th=6.1 ppm; d= 2.6; effective porosity of 0.2 or a rock: water ratio of 4= (0.8/0.2). Thus the age of this groundwater was found to be:

t = He/[10-7 ζHe (1.21U + 0.287Th) d (rock: water)]

t =1000x10-8/ [10-7(1){1.21(1.7x10-6) + 0.287(6.1x10-6)} (2.6)(4)] =2.5x106 years

The age obtained for deep water is approximate because of uncertainty in the criteria applied to the calculation. However, it is of utmost importance: water resources are not renewed, but it is completely protected from the surface, and then they are immune to the pollution of the human origin.

Helium can be measured reliably in the water with a 104 year-old, but the age of groundwater varies greatly and can be up to 108 years. In short, the various helium-based age equation criteria can be estimated well, and water age can be approximated. Thus, the methods available cover a full range of groundwater, with some overlap: (tritium), 102-103 years (14C), 105-106 years (36Cl) and (104-108 (4He years and 105-108 years (40Ar) .

Regards

Good discussion....Following