This paper presents a numerical model to investigate the migration of BTEX (benzene, toluene, ethylbenzene, and xylene) within a fractured aquifer system at the scale of a single fracture under the coupled effect of various transport processes such as dissolution, sorption, biodegradation. The developed model also considers the influence of equilibrium- and kinetic-controlled sorption scenarios on BTEX transport. Further, the transport characteristics of dissolved BTEX within the fracture-matrix system (FMS) are obtained by carrying out the spatial moment analysis on the concentration profiles simulated. In this study, the spatial moment analysis is conducted to estimate the following transport characteristics of dissolved BTEX: (a) velocity within the fracture, (b) dispersion coefficient within the fracture, (c) dissolved mass within the matrix. In order to investigate the sensitivity of various input parameters, two sensitivity indices are computed based on the variation in the velocity of dissolved BTEX constituent within the fracture (SI_vel) and on the variation in the dissolved mass of BTEX constituents within the matrix (SI_mat). Results from the present simulation study suggest that the sorption and biodegradation reactions influence the concentration distribution of highly soluble BTEX constituents (benzene, toluene) within the FMS significantly. The influence of biodegradation on the migration of BTEX within the FMS is found to be more when it co-occurs with the sorption reaction. The effect of sorption and biodegradation reactions on the mobility and dispersion coefficient of dissolved BTEX constituents within the FMS is found to be significant during the early simulation period.
