Microbial Degradation of Carbonyl Sulfide in soils

Abstract

Acrylic cylinders were packed with 2 kg of soil and carbonyl sulfide (COS) gas (100 μl I-1) was introduced to the columns at a rate of 0.5 1 min-1. The COS concentration of the outlet gas reached equilibrium at 50 μl 1-1 within a few minutes in the cylinder packed with sandy soil but was less than the detection limit for 24 h in the cylinder with Andosol. Sterilized soils did not show any decrease in COS. The amount of sulfate in the sandy soil increased on the introduction of COS for 24 h, and this suggested that approximately 48% of the sulfur moieties of COS were converted to sulfate by the microbial activity. Batchwise experiments adding high concentrations of COS such as 8000 μl I-1 into sealed flasks also showed a rapid degradation of COS. Batchwise experiments with Andosol were performed to clarify the relationship between the activity to degrade COS and temperature, soil water content or microbial biomass. COS-degrading activity rose with the increase in temperature and fell with the increase in soil water content. The rate constant and microbial biomass had a good correlation (correlation coefficients.79). Our results indicate that COS-degrading microorganisms are widely distributed in soils, and serve as a possible sink of COS in natural environments. © 2002, Japanese Society of Microbial Ecology & The Japanese Society of Soil Microbiology. All rights reserved.