Consider the diffusion of O2 gas through air in the pores of a column of dry sandy soil. The temperature of the systems is 25C and the total pressure of the systems is 1 atm. The soil bed depth is 1 m and the void fraction is 0.20. The partial pressure of O2 at the top of the column is 0.23 atm while at the bottom, the partial pressure is 0 atm. A tortuosity of 2 can be assumed. Calculate the rate of diffusion, in g/m2h of O2 in air at steady state. [HINT: Due to the tortuous nature of the paths, the diffusivity in air will be reduced by a factor equal to the tortuosity.]