Temperature Dependence of Solute Reaction Parameters

Several of the diffusion (Dw, Dg), zero-order production (γw, γs, γg), first-order degradation (μw’, μs’, μg’, μw, μs, and μg), and adsorption (ks, kg, β, η, ω) coefficients may be strongly dependent upon temperature. HYDRUS assumes that this dependency can be expressed by the Arrhenius equation [Stumm and Morgan, 1981]. This equation can be expressed in the general form

where ar and aT are values of the coefficient being considered at a reference absolute temperature TrA and absolute temperature TA, respectively; Ru is the universal gas constant, and Ea [ML2T-2M-1] is the activation energy of the particular reaction or process being modeled.

The activation energy characterizing the temperature dependence of the solute transport and reaction parameters is entered in the dialog window.

When the Fumigant option is active, the fifth variable (normally reserved for the Frendlich exponent) is used to enter the activation energy for the resistance of surface tarp.