Photochemistry of reduced sulfur compounds in a landfill environment

This study examines the distribution characteristics of reduced sulfur compounds (RSCs such as DMS, CS2, H2S, DMDS, and CH3SH) and their photochemical reactions in landfill air. The photochemical conversions of RSCs to a further oxidized form, SO2 were evaluated in the landfill site using a photochemical box model. Measurements of RSCs were carried out from landfill areas in Daegu, Korea, during a wintertime period (e.g., 13–16 Jan 2004). This study indicated that H2S was the most dominant RSC in the landfill, with the concentrations of 4.2±5.8 ppbv. The chemical species of RSCs, which may exert influences on the SO2 production depending on sampling conditions, were found to include DMS, DMDS, and H2S. In general, the RSC contribution to the observed SO2 levels was insignificant in the sampling sites investigated. Overall, the extent of the RSC oxidation to the observed SO2 varied dramatically during the sampling period. The photochemical conversion of the RSCs in the landfill environment can account for about 15% of the observed SO2, on average. There was a strong correlation between DMS and SO2 concentration levels during the study period.