Short‐lived alkyl iodides and bromides at Mace Head, Ireland: Links to biogenic sources and halogen oxide production

摘要: Automated in situ gas chromatograph/mass spectrometer (GC/MS) measurements of a range predominantly biogenic alkyl halides air, including CHBr3, CHBr2Cl, CH3Br, C2H5Br, CH3I, C2H5I, CH2ICl, CH2I2, and the hitherto unreported CH2IBr were made at Mace Head during 3-week period May 1997. C3H7I CH3CHICH3 monitored but not detected. Positive correlations observed between polyhalomethane pairs CHBr3/CHBr2Cl CHBr3/CH2IBr monohalomethane pair CH3I/C2H5I, which are interpreted terms common or linked marine sources. During periods when air masses affected by emissions from local seaweed beds, concentrations only showed remarkable correlation also maximized low water. These first field observations to provide evidence for link tidal cycle, polyhalomethanes potential production. The calculated total flux iodine atoms into boundary layer organic gaseous precursors was dominated photolytic destruction CH2I2. Photolysis CH3I contributed less than 3%. peak campaign coincided with highest measured levels oxide radicals, as determined using Differential Optical Absorption Spectrometry (DOAS).