Paulot F, Wunch D, Crounse J D, Toon G C, Millet D B, DeCarlo P F, Vigouroux C, Deutscher N M, González Abad G, Notholt J, Warneke T, Hannigan J W, Warneke C, de Gouw J A, Dunlea E J, De Mazière M, Griffith D W T, Bernath P, Jimenez J L, Wennberg P O
Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, California, USA.
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
Atmos Chem Phys. 2011 Mar;11(5):1989-2013. doi: 10.5194/acp-11-1989-2011. Epub 2011 Feb 4.
We present a detailed budget of formic and acetic acids, two of the most abundant trace gases in the atmosphere. Our bottom-up estimate of the global source of formic and acetic acids are ∼1200 and ∼1400Gmolyr, dominated by photochemical oxidation of biogenic volatile organic compounds, in particular isoprene. Their sinks are dominated by wet and dry deposition. We use the GEOS-Chem chemical transport model to evaluate this budget against an extensive suite of measurements from ground, ship and satellite-based Fourier transform spectrometers, as well as from several aircraft campaigns over North America. The model captures the seasonality of formic and acetic acids well but generally underestimates their concentration, particularly in the Northern midlatitudes. We infer that the source of both carboxylic acids may be up to 50% greater than our estimate and report evidence for a long-lived missing secondary source of carboxylic acids that may be associated with the aging of organic aerosols. Vertical profiles of formic acid in the upper troposphere support a negative temperature dependence of the reaction between formic acid and the hydroxyl radical as suggested by several theoretical studies.
我们给出了甲酸和乙酸的详细收支情况，这两种是大气中含量最为丰富的痕量气体。我们通过自下而上的方法估算得出，全球甲酸和乙酸的源分别约为1200 Gmol/yr和1400 Gmol/yr，主要来源于生物挥发性有机化合物的光化学氧化，尤其是异戊二烯。它们的汇主要是湿沉降和干沉降。我们使用GEOS-Chem化学传输模型，对照来自地面、船舶和卫星傅里叶变换光谱仪的大量测量数据，以及北美地区几次飞机观测活动的数据，来评估这一收支情况。该模型能很好地捕捉甲酸和乙酸的季节性变化，但总体上低估了它们的浓度，尤其是在北半球中纬度地区。我们推断，这两种羧酸的源可能比我们的估计值高出50%，并报告了存在一种可能与有机气溶胶老化有关的长期缺失的羧酸二次源的证据。对流层上部甲酸的垂直分布情况支持了几项理论研究提出的甲酸与羟基自由基之间反应的负温度依赖性。
