Chemistry of Protostellar Clumps in the High-mass, Star-forming Filamentary Infrared Dark Cloud G034.43+00.24

To search for the potential chemical dependence on physical conditions, we have carried out the study of chemistry on the nine protostellar clumps of the high-mass star-forming infrared dark cloud G034.43+00.24, with observations of several similar to 1 mm lines by the Atacama Pathfinder EXperiment telescope. They include CO/(CO)-C-13/(CO)-O-18(2-1), HCO+/(HCO+)-C-13(3-2), HCN/(HCN)-C-13(3-2), HNC (3-2), CS/(CS)-S-34(5-4), SiO.(6 -5), SO(6-5), p-H2CO.(3-2), and CH3OH.(5-4). All the clumps are simply grouped into two classes: highluminosity protostellar clumps (MM1-MM4, L-bol > similar to 103 L-circle dot) and low-luminosity protostellar clumps (MM5-MM9, L-bol << 10(3) L-circle dot). Our observations indicate that (CO)-C-13 suffers either no or low depletion in the clump environment of G034.43+00.24 as characterized by a nearly constant level of the (CO)-C-13 abundance distribution. For the remaining relatively dense gas tracers, we find that their abundances tend to get enhanced in the highluminosity protostellar clumps as opposed to the low-luminosity counterparts. We suggest that for most, if not all, of the dense gas tracers the high abundance mainly arises from both the high luminosities and associated outflows of the high-luminosity protostellar clumps while the low abundance could be due to the lack of such active starforming activities in the low-luminosity protostellar clumps.