“…As a result of the metal depletion onto dust grains the gas-phase elemental abundances are altered to H: 1.00, He: 9.50 Â 10 À2 , Li: 5.40 Â 10 À11 , B: 8.90 Â 10 À11 , C: 3.00 Â 10 À4 , N: 7.00 Â 10 À5 , O: 4.00 Â 10 À4 , Ne: 6.00 Â 10 À5 , Na: 3.00 Â 10 À7 , Mg: 3.00 Â 10 À6 , Al: 2.00 Â 10 À7 , Si: 4.00 Â 10 À6 , P: 1.60 Â 10 À7 , S: 1.00 Â 10 À5 , Cl: 1.00 Â 10 À7 , Ar: 3.00 Â 10 À6 , K: 1.10 Â 10 À8 , Ca: 2.00 Â 10 À8 , Ti: 5.80 Â 10 À10 , V: 1.00 Â 10 À10 , Cr: 1.00 Â 10 À8 , Mn: 2.30 Â 10 À8 , Fe: 3.00 Â 10 À6 , Ni: 1.00 Â 10 À7 , Cu: 1.50 Â 10 À9 , and Zn: 2.00 Â 10 À8 . These depleted elemental abundances are based on results of several studies of the Orion nebula (Baldwin et al 1991;Rubin et al 1991;Rubin, Dufour, & Walter 1993;Rubin et al 1992;Osterbrock, Tran, & Veilleux 1992). Note that beryllium, fluorine, scandium, and cobalt are not included in the calculations for the dusty models.…”