Top panel: Median integrated intensity measurements for radii less than 50 and 100 pc from the centre of the disc, including species such as CO, C i, and C ii, collected over a time span of 3–8 Myr. The data reveal a declining trend in intensity over time, more pronounced at larger radii (<100 pc), indicating that intensity decreases as distance from the centre increases in both AGN and NoAGN models. In the inner and outer regions, median intensities of C i, C ii, and CO are lower in the AGN model for time-scales below 7 Myr. However, after 7 Myr, the inner region of the AGN model shows an increase in median CO intensity, followed by increases in C i and C ii at 8 Myr, suggesting AGN influence on the distribution and abundance of these species. Bottom panel: Median integrated intensity ratios for C i/CO, C ii/CO, and C i/C ii for radii smaller than 50 and 100 pc. The trends indicate a gradual decrease in C i/CO and C i/C ii ratios over time, reflecting a diminishing abundance of C i relative to C ii. Notably, the C i/C ii ratio increases after 6 Myr for radii below 50 pc. C ii/CO ratios exhibit a generally increasing pattern over time. In the inner regions, AGN models show lower median values for C i/CO, C ii/CO, and C i/C ii for time-scales below 8 Myr compared to NoAGN models, with a notable increase in C i/CO at 8 Myr for the AGN model. Overall, the NoAGN model shows a higher abundance of C i relative to CO before 7 Myr, a trend that reverses at 8 Myr in the inner regions.