Acetaldehyde and acetone in the Arctic snowpack during the ALERT2000 campaign. Snowpack composition, incorporation processes and atmospheric impact

摘要

Acetaldehyde and acetone were measured in the seasonal snowpack near Alert (Nunavut, Canadian Arctic) in February and April 2000. Acetaldehyde concentrations in fresh surface snow in February were about 2.5 ppbw, decreasing to 1 ppbw after several days, while gas-phase acetaldehyde was about 75 pptv. Values for aged layers were 1.3-2.6 ppbw. In April, values for fresh snow were 5-10 ppbw, decreasing to 1-4 ppbw after several days (gas- phase values were around 230 pptv). Values for aged layers were in the range 0.7-3 ppbw. Snow-phase acetaldehyde represented 67/100 of the (snow + atmospheric mixing layer) system in winter and 94/100 in spring.