Eighteen measurements of acetonitrile have been made at two rural sites about 40 km from Tucson, Arizona. Mean mixing ratio was 56 (¿ 20) ppt; no value greater than 84 ppt was observed. Limit of detection was between 10 and 20 ppt. Allowing for some contamination from Tucson, the results are compatible with observed stratospheric mixing ratios, small tropospheric loss, and a small global surface source. |