Analytical model for one-dimensional transport of organic contaminants in multi-layered media considering advection-diffusion-adsorption-degradation

For the problem of one-dimensional transport of organic contaminants in multi-layered media, a one-dimensional organic contaminants transport model in multi-layered media considering advection-diffusion-adsorption-degradation is established, and the analytical solution for the model is obtained by using the separation variable method. The correctness of the established one-dimensional transport analytical model is verified by comparing the calculated results with those of the existing analytical solution and the numerical method. Based on the established analytical model, the one-dimensional transport process of organic contaminants in a four-layer soil is taken as an example to conduct the parameter analysis. The results show that the advection caused by the leachate head h_w will accelerate the transport process and increase the bottom flux. Compared with that at h_w of 0.0 m, the bottom flux at 2.0 m can be increased by more than one order of magnitude. The degradation will reduce the concentration and bottom flux. When the transport process reaches the steady state, the bottom flux at degradation half-life t_1/2 of 100 a can be reduced by about 45% compared with that at t_1/2 of infinity. The increase of the Robin boundary constant α will reduce the concentration in the bottom region, and also will increase the bottom flux, which varies in the same order of magnitude under different α.