Pie charts of the percentage contributions of the dominant oxygen-bearing molecules to the total elemental oxygen abundance (=3.2 × 10⁻⁴) at r ~ 60 au (T_gas ~ 150 K, inside the water snowline) in the NGC 1333-IRAS 2A envelope model (top three charts) and the NGC 1333-IRAS 4A envelope model (bottom three charts). The left, middle, and right charts show the contributions with L_X = 10²⁸, 10³⁰, and 10³² erg s⁻¹, respectively. The red, dark blue, purple, black, green, and light blue slices are respectively the contributions of CO, H₂O, O, O₂, CO₂, and other molecules (such as CH₃OH).