Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry
Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry
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DOI：
10.5194/acp-12-9529-2012
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发表时间：
2012-10
影响因子：
6.3
通讯作者：
J. Digangi;S. Henry;A. Kammrath;E. S. Boyle;L. Kaser;R. Schnitzhofer;M. Graus;A. Turnipseed;J. P
中科院分区：
文献类型：
--
作者：
J. Digangi;S. Henry;A. Kammrath;E. S. Boyle;L. Kaser;R. Schnitzhofer;M. Graus;A. Turnipseed;J. P
我们提供了两个农村活动BEARPEX 2009和BEACHON-ROCs的甲醛和乙二醛的同步快速原位测量，这两个活动都位于黄松林，排放以生物挥发性有机化合物(VOC)为主。尽管甲醛和乙二醛的浓度有很大的差异，但乙二醛和甲醛的比率，RGF，在近两周的测量中显示出非常规则的日循环。RGF的唯一偏差是朝向更高的值，是2009年BEARPEX期间的生物质燃烧事件和BEACHON-ROCS期间非常新鲜的人为影响的结果。乙二醛和甲醛浓度的其他快速变化对RGF几乎没有任何影响，可能反映了低NO和高NO之间的过渡。与生物源活性VOC混合物相比，人为活性VOC混合物和生物质燃烧引起的RGF增加的趋势是强劲的，这是因为观察到的RGF变化发生的时间尺度很短。卫星检索显示，生态区的RGF较高，这与我们观察到的趋势相反。解决这一差异仍然很重要，特别是考虑到卫星反演和现场测量对于模型比较的重要性。此外，我们认为，对于生物或人为的反应性VOC混合物，RGF是一个有用的指标，并且与乙二醛和甲醛的绝对浓度相结合，进一步代表了通过NOx对整个反应性VOC处理的人为影响程度的有用指标。特别是，RGF不仅提供了关于气团中主导反应性的VOC的信息，而且还提供了直接与臭氧和次级有机气溶胶产生相耦合的VOC处理本身的信息。
We present simultaneous fast, in-situ measurements of formaldehyde and glyoxal from two rural campaigns, BEARPEX 2009 and BEACHON-ROCS, both located in Pinus Ponderosa forests with emissions dominated by biogenic volatile organic compounds (VOCs). Despite considerable variability in the formaldehyde and glyoxal concentrations, the ratio of glyoxal to formaldehyde, RGF, displayed a very regular diurnal cycle over nearly 2 weeks of measurements. The only deviations in RGF were toward higher values and were the result of a biomass burning event during BEARPEX 2009 and very fresh anthropogenic influence during BEACHON-ROCS. Other rapid changes in glyoxal and formaldehyde concentrations have hardly any affect on RGF and could reflect transitions between low and high NO regimes. The trend of increased RGF from both anthropogenic reactive VOC mixtures and biomass burning compared to biogenic reactive VOC mixtures is robust due to the short timescales over which the observed changes in RGF occurred. Satellite retrievals, which suggest higher RGF for biogenic areas, are in contrast to our observed trends. It remains important to address this discrepancy, especially in view of the importance of satellite retrievals and in situ measurements for model comparison. In addition, we propose that RGF represents a useful metric for biogenic or anthropogenic reactive VOC mixtures and, in combination with absolute concentrations of glyoxal and formaldehyde, furthermore represents a useful metric for the extent of anthropogenic influence on overall reactive VOC processing via NOx. In particular, RGF yields information about not simply the VOCs dominating reactivity in an airmass, but the VOC processing itself that is directly coupled to ozone and secondary organic aerosol production.