High-mass IR-dark clumps MALT90 molecular content

(1) Eleven sources have significant SiO detection (over 3{sigma}) which usually indicates outflow activity. (2) Thirteen sources are found with blue profiles in both/either HCO+ and/or HNC lines and clump mass infall rates are estimated to be in the range of 0.2x10^-3^M_{sun}_/yr-1.8x10^-2^M_{sun}_/yr. (3) The excitation temperature is obtained as <24K for all sources.

(4) The column densities for optically thin lines of H^13^CO^+^ and HN^13^C (1-0) are in the range of 0.4-8.8(x10^12^)cm^-2^, and 0.9-11.9(x10^12^)cm^-2^, respectively, while it is in the range of 0.1-7.5(x10^14^)cm^-2^ for HCO^+^ and HNC lines. The column densities for N^13^CH^+^ were ranging between 4.4-275.7(x10^12^)cm^-2^ as expected from cold dense regions. (5) Large line widths of N^13^CH^+^ might indicate turbulence and large line widths of HCO^+^, HNC, and SiO indicate outflow activities.

(6) Mean optical depths are 20.32, and 23.19 for optically thick HCO^+^ and HCN lines, and 0.39 and 0.45 for their optically thin isotopologues H^13^CO^+^ and HN^13^C (1-0), respectively. This study reveals the physical and chemical properties of 30 high-mass IR-dark clumps and the interesting targets among them based on their emission line morphology and kinematics.