Pie charts showing the percentage of each chemical element (from top to bottom: carbon, oxygen, nitrogen and sulphur) that is carried in different volatile ices (the abundances of CO₂ and SO₂ were doubled when accounting for the oxygen budget in the second row, and the abundance of S₂ was likewise doubled when accounting for the sulphur budget in the fourth row). Left column features the starting abundances for pebble drift starting at 200 AU. The second, third and fourth columns represent fast (10 kyr), medium (100 kyr) and slow drift (1 Myr), respectively. Going from left to right therefore corresponds to increasing the chemical timescales. The pie charts in these columns represent pebble ice compositions at 18.9 AU, which is the innermost midplane radius at which none of the shown volatile molecules have desorbed yet (see Table 1), except for CO ice, which is only present in the ices at the beginning of drifting (see "Carbon" and "Oxygen" pie charts in the first column).