Sources and sinks of acetone, methanol, and acetaldehyde in North Atlantic marine air

[摘要] Measurements of acetone, methanol, acetaldehyde and a range of non-methane hydrocarbonshave been made in North Atlantic marine air at the Mace Head observatory. Under maritimeconditions the combination of OVOCs (acetone, methanol and acetaldehyde) contributed upto 85% of the total mass of measured non methane organics in air and up to 80% ofthe OH radical organic sink, when compared with the sum of all other organic compoundsincluding non-methane hydrocarbons, DMS and OH-reactive halocarbons (trichloromethane andtetrachloroethylene). The observations showed anomalies in the variance and abundance ofacetaldehyde and acetone over that expected for species with a remote terrestrial emissionsource and OH controlled chemical lifetime.A detailed model incorporating an explicitchemical degradation mechanism indicated in situ formation during air mass transportwas on timescales longer than the atmospheric lifetime of precursor hydrocarbons or primaryemission. The period over which this process was significant was similar to that of airmassmotion on intercontinental scales, and formation via this route may reproduce that of awidespread diffuse source. The model indicates that continued short chain OVOC formationoccurs many days from the point of emission, via longer lived intermediates ofoxidation such as organic peroxides and long chain alcohols.

[学科分类] 大气科学