In situ measurement of atmospheric HCFC-22 at the Shangdianzi GAW regional station

An in situ GC-ECD monitoring system was established at the Shangdianzi GAW Regional station from April 2007 to March 2008, and the mixing ratio of atmospheric HCFC-22 was (278.1±113.6)×10^-12 (mol/mol). A "R" statistical software was applied to the HCFC-22 time series to separate background and pollution data. The background HCFC-22 mixing ratio was (199.5±5.1)×10^-12, close to northern hemisphere background level observed at Mace Head and Trinidad Head stations. The pollution HCFC-22 mixing ratio was (312.1±121.0)×10^-12 due to anthropogenic emission from various regions and air mass transport. There was no significant seasonal variability of background data. However, pollution data was much higher in summer than that in winter, and elevated up to 100.9×10^-12 in July than in January attribute to seasonal emission characteristics. The mean HCFC-22 mixing ratio from southwest wind sector (327.3×10^-12) was much higher than that of northeast sector (236.2×10^-12). The W-WSW-SW wind sector has a positive contribution to the HCFC-22 level, while NNE-N-NE has a large negative contribution.