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tokens: consequence of the release of the S-species from the icy grain mantles because of thermal and nonthermal desorption and sputtering. Contrary to dark clouds and prestellar cores, in B1b the S depletion is comparable to that of C and O, which explains the high abundances of S-bearing species in this core. Table 4 Elemental abundances relative to H. Notes. (a) From the compilation by Agúndez Wakelam (2013) ; (b) this work; (c) elemental abundance in the gas phase; (d) depletion factor = (X/H)/(X/H). The abundance of sulfur in grains is very uncertain. Thus far, the only S-bearing molecule unambiguously detected in ice mantles is OCS, because of its large band strength in the infrared ( Geballe et al. 1985 ; Palumbo et al. 1995 ), and maybe SO ( Boogert et al. 1997 ), but there are only upper limits of the solid HS abundance ( Jiménez-Escobar Muñoz Caro 2011 ), which is thought to be the main sulfur reservoir in the ice. Measurements of the sulfur depletion are derived by comparing the predictions of gas-phase chemical models with the observed abundances of the main S-bearing species. As reported above, chemical models are limited by the uncertainty in the reaction rates and the poorly known [O]/[O] ratio and the exact value of the sulfur depletion is uncertain. Our results suggest, however, that the sulfur depletion in Barnard 1b is not as extreme as in dark clouds where the abundance of S-bearing species is lower. This moderate sulfur depletion could be the consequence of the star formation activity in the region. B1b is irradiated on its eastern side by UV photons from the nearby Herbig Ae stars LkH 327 and LkH 328 ( Walawender et al. 2009 ; Young et al. 2015 ). On its western side, B1b is impacted by the outflows associated with B1a and B1d ( Hatchell et al. 2007 ). Not unrelated, the level of turbulence in B1 (0.4 km s) is higher than in cold cores such as L1544, TMC-1 or L134N (0.1 km s). Sputtering induced by collisions may be efficient in this turbulent environment to erode the icy mantles and release the sulfuretted species to the gas phase. Sputtering could also explain the high abundances of complex molecules observed in this core ( Marcelino et al. 2009 ; Cernicharo et al. 2012 ). The main drawback of this interpretation is that it would also imply a low depletion of CO that is not observed. Another possibility is that the moderate sulfur depletion is a consequence of the rapid collapse of B1b. Aikawa et al. (2005) investigated the impact of different collapse timescales on the gas chemistry. The initial conditions of their first model lie close to the critical Bonnor-Ebert sphere with a central density of 10 cm. When the central density of the core reaches 10 cm, the S-bearing species were totally depleted at AU. In the second case, internal gravity overwhelms pressure and the collapse is much faster (about 0.1 Myr). When the central density of the core reaches 10 cm, molecules such as CS, SO, and CS have abundances of 10 in the