We present the Matlab code used for the paper "Heavy Metal Pollution to Shallow Groundwater Aquifer Caused by CO2 Leakage During Geological Carbon Storage (GCS)" Figures 2 and 3 are obtained by sequentially running "startup.m", and "figure_resultf.m" in the folder "leakge-trautz/reactive transport" (remember to change the rootine to "leakge-trautz/reactive transport" when running figure_resultf.m); The simulations for obtaining Figures 2 and 3 are performed using code "trautz_horizontal_2d_new.m" Before running "trautz_horizontal_2d_new.m", we need to initialize the water chemistry in the aquifer (species_0.01.mat ) and the water chemistry of the injection well (species_3.8.mat). This is obtained by running "test_reaction_trautz.m"; note: (i) set k note set initial pressure to 0.01bar" ; )