Function N2SAT(S, T)

'CALCULATE NITROGEN CONCENTRATION AT SATURATION

'Source:  The solubility of nitrogen, oxygen and argon in water and
'         seawater - Weiss (1970) Deep Sea Research V17(4): 721-735.

'Molar volume of nitrogen at STP obtained from NIST website on the
'         thermophysical properties of fluid systems:

'         http://webbook.nist.gov/chemistry/fluid/


'Input:       S = Salinity (0/00)
'             T = Temp (deg C)

'Output:      Nitrogen saturation at one atmosphere (umol/kg).


'DEFINE CONSTANTS, ETC FOR SATURATION CALCULATION

'   The constants -177.0212, etc., are used for units of ml N2/kg.

  T1 = (T + 273.15) / 100

  NSAT = -177.0212 + 254.6078 / T1 + 146.3611 * log(T1) - 22.0933 * T1
  NSAT = NSAT + S * (-0.054052 + T1 * (0.027266 - 0.0038430 * T1))
  NSAT = exp(NSAT)


'CONVERT FROM ML/KG TO UM/KG

  N2SAT = NSAT * 1000 / 22.404

End Function