A continuous time dynamic system of an unsteady state fugacity model i
s presented. Properties of this model as stability are studied. In ord
er to evaluate numerical results a discretization preserving the stabi
lity and yielding the positivity property of the model is used. Finall
y, algorithms to determine the values of the fugacities, the concentra
tions and the dissipation time are given. The above study is illustrat
ed with numerical results in a three compartmental environmental syste
m. (C) 1998 Elsevier Science Inc. All rights reserved.