Methyl tert-butyl ether (MTBE) in snow samples in Germany

Abstract

In the present study, experimental results of methyl tert-butyl ether (MTBE) analysis in 43 snow samples from 13 various locations during two winter seasons are presented. MTBE could be detected in 65% of the samples. The concentrations ranged from 11 to 631 ng L −1. The comparison to formerly analysed rainwater samples indicates atmospheric transfer of MTBE from urban to rural areas preferentially in winter due to lower atmospheric degradation rates and suggests that MTBE is more effectively scavenged from the atmosphere by snow than by rain. This result is in contrast to calculated distribution coefficients K Rain/Air (−6.8°) and K Snow/Air (−6.8°) using different values for the specific snow surface area. MTBE concentrations measured in the collected snow samples from rural areas did not differ from MTBE concentrations in snow samples collected in the urban area of Frankfurt/M. The explanatory factor for this finding is also the lower atmospheric degradation rate of MTBE in winter. Particular meteorological conditions at the monitoring site Schmücke most probably explain maximum concentrations of 631 and 438 ng L −1 measured at this site. Decreasing MTBE amounts in snow samples collected at the monitoring site Schauinsland in January 2003 might have been due to increasing ambient temperatures. Varying MTBE amounts in snow samples collected at the Taunus Observatorium (Kleiner Feldberg) in February 2002 and in January/February 2003 cannot be explained by ambient temperatures. In future studies concurrent air sampling and morphological characterisation of the sampled snow would be required to clarify and confirm the results of the present study.