| A’ |
= |
amount of excess air in units consistent with ci (e.g. molM-1, typically in ccSTP/g, ccSTP/kg, or mole/kg) |
| Age |
= |
elapsed time since groundwater recharge, i.e., exposure to atmosphere (T) |
| [latex]{Age}_{\min}[/latex] |
= |
minimum age of the sample (T) |
| C |
= |
aqueous concentration (molM-1, typically in mole/kg or TU for 3H) |
| Co |
= |
concentration at an arbitrary time; a convenient choice is 1950 when the precipitation [latex]_{}^{3}H[/latex] record begins after 1950. (molM-1, typically in mole/kg or TU for 3H) |
| [latex]C_{Ar}[/latex] |
= |
concentration of Ar in water (L3M-1, typically in ccSTP/g) |
| [latex]C_{background}[/latex] |
= |
[latex]_{}^{3}H[/latex] concentration in precipitation at the time the sample was collected (TU) |
| [latex]c_{i}^{water}[/latex] |
= |
concentration of gas i in the water phase (L3M-1, typically in ccSTP/g) |
| [latex]c_{i}[/latex] |
= |
concentration of gas i in the water phase (L3M-1, typically in ccSTP/g) |
| [latex]C_{i,eq}[/latex] |
= |
concentration of air saturated water, ASW, (L3M-1, typically in ccSTP/g or ccSTP/kg) |
| [latex]C_{i}^{gas}[/latex] |
= |
concentration of gas i in the gas phase (moles/L) |
| Cm,i |
= |
measured concentration of the ith gas (moles/L) |
| [latex]C_{m,Ne}[/latex] |
= |
measured concentration of dissolved [latex]Ne[/latex] (ccSTP/g) |
| [latex]C_{meas}[/latex] |
= |
sample concentration (L3M-1, typically in ccSTP/g) |
| [latex]C_{N_{2}}[/latex] |
= |
concentration of [latex]N_{2}[/latex] in water (L3M-1, typically in ccSTP/g) |
| [latex]C_{O_{2}}[/latex] |
= |
concentration of [latex]O_{2}[/latex] in water (L3M-1, typically in ccSTP/g) |
| cs,i |
= |
simulated concentration of the ith gas (L3M-1, typically in ccSTP/g or ccSTP/kg) |
| Csol,Ne |
= |
theoretical concentration of [latex]Ne[/latex] in equilibrium with the atmosphere (L3M-1, typically in ccSTP/g or ccSTP/kg) |
| ∆t |
= |
sample time −[latex]\ C_{0}[/latex] time (T) |
| e |
= |
temperature dependent vapor pressure of water (ML-1T-2, typically in atm or mmHg) |
| e(T) |
= |
vapor pressure of water at temperature T (ML-1T-2, typically in atm or mmHg) |
| F |
= |
fractionation factor (dimensionless) |
| [latex]_{}^{3}{He}_{atm}^{}[/latex] |
= |
[latex]_{}^{3}{He}[/latex] derived from atmospheric sources (L3M-1) |
| [latex]_{}^{3}{He}_{EA}[/latex] |
= |
[latex]_{}^{3}{He}[/latex] derived from excess air (L3M-1) |
| [latex]_{}^{3}{He}_{m}^{}[/latex] |
= |
[latex]_{}^{3}{He}[/latex] measured in the groundwater sample (L3M-1) |
| [latex]_{}^{3}{He}_{sol}[/latex] |
= |
[latex]_{}^{3}{He}[/latex] concentration at solubility equilibrium with the atmosphere at recharge temperature and elevation (L3M-1) |
| [latex]_{}^{3}{He}_{terr}^{}[/latex] |
= |
[latex]_{}^{3}{He}[/latex] from terrigenic sources, including crustal [latex]_{}^{3}{He}[/latex] ([latex]_{}^{3}{He}[/latex]crust) and mantle [latex]_{}^{3}{He}[/latex] ([latex]_{}^{3}{He}[/latex]man) (L3M-1) |
| [latex]_{}^{4}{He}_{m}[/latex] |
= |
Measured concentration of [latex]_{}^{4}{He}[/latex] (L3M-1) |
| Kh |
= |
temperature- and salinity-dependent equilibrium constant (molM‑2LT2 typically in moles kg‑1atm‑1) |
| [latex]K_{w,Ar}[/latex] |
= |
dimensioned Henry Coefficient for [latex]Ar[/latex] (molM‑2LT2, typically in moles kg‑1atm‑1) |
| [latex]K_{w,i}^{cc}[/latex] |
= |
dimensionless Henry Coefficient for gas i (dimensionless) |
| [latex]K_{w,i}[/latex] |
= |
Henry Coefficient for gas i (molM‑2LT2, typically in moles kg‑1atm‑1) |
| [latex]K_{w,i}(T,S)[/latex] |
= |
Henry Coefficient of gas i at temperature T and salinity S (molM‑2LT2, typically in moles kg‑1atm‑1) |
| [latex]K_{w,N_{2}}[/latex] |
= |
dimensioned Henry Coefficient for [latex]N_{2}[/latex](molM‑2LT2, typically in moles kg‑1atm‑1) |
| [latex]K_{w,O_{2}}[/latex] |
= |
dimensioned Henry Coefficient for [latex]O_{2}[/latex](molM‑2LT2, typically in moles kg‑1atm‑1) |
| [latex]L_{vz}[/latex] |
= |
vertical distance from land surface to the water table (L) |
| [latex]\lambda[/latex] |
= |
tritium decay constant (T-1, 0.05626 yr–1) |
| P |
= |
atmospheric pressure (ML-1T-2, typically in atm) |
| [latex]P_{0}[/latex] |
= |
pressure at elevation zero (ML-1T-2, 1 atm) |
| [latex]p_{i}[/latex] |
= |
partial pressure of gas i in the gas phase (ML-1T-2, typically in atm) |
| [latex]q[/latex] |
= |
recharge rate (LT-1, typically in mm/yr) |
| [latex]R_{m}[/latex] |
= |
measured [latex]\frac{_{}^{3}{He}}{_{}^{4}{He}}[/latex] ratio; commonly referred to simply as [latex]R[/latex], as in the notation [latex]\frac{R}{R_{a}}[/latex] (dimensionless) |
| [latex]R_{terr}[/latex] |
= |
[latex]\frac{_{}^{3}{He}}{_{}^{4}{He}}[/latex] ratio for terrigenic [latex]He[/latex], given in Table 4, (dimensionless) |
| S |
= |
salinity of the sample (MM-1), often in part per thousand (1000 MM-1) |
| [latex]\sigma_{i}[/latex] |
= |
measurement error of the ith gas (L3M-1, typically in ccSTP/kg) |
| T |
= |
temperature (typically in °C) |
| t |
= |
time of sampling (T) |
| TDGP |
= |
total dissolved gas pressure (ML-1T-2) |
| [latex]t_{vz}[/latex] |
= |
vadose zone transport time (T) |
| [latex]\theta_{vz}[/latex] |
= |
mobile water content (dimensionless) |
| x |
= |
dry air mole fraction (dimensionless) |
| [latex]x_{i}[/latex] |
= |
fraction of gas i (mixing ratio) in the dry atmosphere (dimensionless) |
| [latex]Z[/latex] |
= |
elevation (L) |
| [latex]Z_{s}[/latex] |
= |
scaling factor (dimensionless) |
