AUTOMOTIVE TIRE WEAR AS A SOURCE FOR ATMOSPHERIC OCS AND CS2

The emission of CS2, OCS and traces of SO2 from mixtures of fifteen di fferent ground tire treads has been detected in laboratory experiments using gas chromatography/flame photometric detection (GC/FPD) and gas chromatography/mass spectrometry (GC/MS). Samples of ground tire part icles (60-100 mesh) were flushed at different temperatures using eithe r clean nitrogen gas or a mixture of 100 ppb O3 in N2. CS2 was the dom inant sulfur gas detected in all of the experiments. OCS and CS2 emiss ions increased strongly with temperature and were independent of the p resence of O3. In contrast, SO2 was observed only at high ozone levels . It is roughly estimated that tire wear may produce as much as 0.04 /- 0.004 Tg S (OCS) yr-1 or about 6.7% of the total OCS flux into the atmosphere. Therefore, this as yet undescribed automotive source may m ake a small but significant contribution to the atmospheric OCS budget .