Abundances of volatile ices on a drifting pebble as a function of radius (time), where the pebbles moves inwards with time. Left is drift from 128 AU, right is drift from 200 AU. Top panels are for species with abundances larger than 10⁻⁵ wrt H (H₂O, CO₂ CH₃OH, NH₃ and CH₄). Bottom panels are for species with abundances ranging from 10⁻⁸–10⁻⁵ (HCN, SO, SO₂, H₂S and S₂). Solid profiles are for slow drift (1 Myr), dashed profiles are for medium drift (100 kyr) and dotted profiles are for fast drift (10 kyr). Colours correspond to the same species in both panels. We note that the top and bottom panels have different dynamical y-axis ranges.