RUI: Aqueous-Phase Photochemistry of Atmospheric Hydrocarbon Oxidation Products

各种碳氢化合物从自然来源和人为来源排放到大气中。异戊二烯(2-甲基-1，3-丁二烯)特别令人感兴趣，因为它在任何单一碳氢化合物中具有最大的全球通量(可能是甲烷除外)，异戊二烯在NOx存在下与羟基自由基(OH)和臭氧(O3)迅速反应生成3-丁烯-2酮(甲基乙烯基酮，MVK)和2-甲基-2-丙二醛(甲基丙烯醛，MACR)。一旦形成，对流层MVK和MACR以及许多其他碳氢化合物氧化产物可能会在气相中发生各种反应。MVK、MACR和其他碳氢化合物氧化产物可能也会分配到大气水滴中，并进行后续的水相反应，导致过氧基(HO2/RO2)和其他氧化剂物种的形成，从而消耗MVK和MACR。过氧基可以破坏对流层的臭氧，并形成过氧化氢，迅速氧化水相中的二氧化硫(SO2)。随后形成的硫酸盐气溶胶有效地对进入的太阳辐射进行反向散射，并对气候产生显著的冷却作用。因此，这些研究人员将研究：1)将MVK、MACR和其他烃类氧化产物从气相分配到水中；2)在典型的大气水滴条件下，MVK、MACR和其他烃类氧化产物的水相光化学；以及3)MVK、MACR和其他烃类氧化产物与选定的光化学氧化剂的水相反应。

A wide variety of hydrocarbons are emitted into the atmosphere from both natural and anthropogenic sources. Isoprene (2-methyl- 1,3-butadiene) is of particular interest because it has the largest global flux of any single hydrocarbon species with the possible exception of methane, Isoprene reacts rapidly with hydroxyl radical (OH) and ozone (O3) in the presence of NOx forming 3-buten-2 one( methyl vinyl ketone, MVK) and 2-methyl-2-propenal (methacrolein, MACR). Once formed, tropospheric MVK and MACR, as well as many other hydrocarbon oxidation products, may undergo a variety of reactions in the gas phase. It is likely that MVK, MACR and other hydrocarbon oxidation products can also partition into atmospheric water drops and undergo subsequent aqueous-phase reactions leading to the formation of peroxyl radicals (HO2/RO2) and other oxidant species, and there by, consuming MVK and MACR. Peroxyl radicals can destroy tropospheric O3 and form peroxides that rapidly oxidize sulfur dioxide (SO2) in the aqueous phase. The sulfate aerosol that is subsequently formed efficiently backscatters incoming solar radiation and exerts a significant cooling effect upon climate. These researchers therefore will study: 1) partitioning of MVK, MACR and other hydrocarbon oxidation products from the gas phase into water, 2) aqueous-phase photochemistry of MVK, MACR, and other hydrocarbon oxidation products under conditions that are typical of atmospheric water drops, and 3) aqueous-phase reactions of MVK, MACR and other hydrocarbon oxidation products with selected photochemical oxidants.