Abstract: In recent years the multicomponent reactive transport model is widely used in earth science and environment field; however, some difficulties lie in its solution. To enhance computational efficiency a decoupling approach is advised to simplify the model. A decoupling approach is presented for heterogeneous media and used to solve the model in this situation. The whole domain is divided into several subdomains according to the reactions that may occur; and the corresponding decoupling matrix is obtained. The concentration boundary between sub-domains is set so that the models in each subdomain can be connected and solved together. A test of reactive transport in one-dimensional heterogeneous domain where reactions followed local equilibrium assumption is taken as an example. The model is solved by proposed method and by PHAST separately; and the corresponding results are compared. The results show that the concentration evolution and distribution solved by decoupling approach has a good agreement with ones solved by PHAST, so as to show that the proposed method has a good applicability.

Key words: decoupling approach, multicomponent reactive transport model, heterogeneity, PHAST soft ware