235
Dissolved Gases Other than CO 2
The total flux is equal to the values through the two boundaries
F = k g (C g – C sg ) = k 1 (C sl – C l )
(6.26)
where C g is the concentration of the gas in the gas phase, C sg is the concentration of gas in
the surface film, C l is the concentration of the gas in the liquid phase, and C sl is the concentration of the gas in the surface film. In the surface film,
C sg = H C sl
(6.27)
where H is the Henry’s law constant. The substitution into Equation 6.26 gives
F = (C g = H C l )/(1/k g + H/ k l ) (C g / H – C l )(1/k l + 1/H k g )
(6.28)
If we define:
1/K g = 1/k g + H/ k l
(6.29)
1/K l = 1/k l + 1/H k g
(6.30)
Equation 6.28 can be rewritten as
F = K g (C g – H C l ) = K l (C g / H – C l )
(6.31)
The total resistance to transport across the air–sea interface R is given by
R = 1/K A + 1/K W
(6.32)
where R g = 1/K g is the resistance of the gas phase and R l = 1/K l is the resistance of the liquid phase. The value of R depends on the exchange constants of the gas and liquid phases
C g
Gas
Gas Film
C sg
Interface
Liquid Film
C sl
Liquid
Figure 6.3
The gas film model for the transport of gases across the air–sea interface.