Stable Carbon Isotope Ratios and the Photochemical Age of Atmospheric Volatile Organic Compounds

作者：Kornilova A; Saccon M; O'Brien J M; Huang L; Rudolph J^*

来源：Atmosphere-Ocean, 2015, 53(1): 7-13.

DOI：10.1080/07055900.2013.822787

• VOC
• photochemical age
• isotope composition
• isotope hydrocarbon clock
• ozone
• nitrogen oxides

The dependence of ozone formation on the mixing ratios of volatile organic compounds (VOCs) and nitrogen oxides (NOx) has been widely studied. In addition to the atmospheric levels of VOCs and NOx, the extent of photochemical processing of VOCs has a strong impact on ozone levels. Although methods for measuring atmospheric mixing ratios of VOCs and NOx are well established and results of those measurements are widely available, determination of the extent of photochemical processing of VOCs, known as photochemical age (PCA), is difficult. In this article a recently developed methodology for the determination of PCA for individual compounds based on the change in their stable carbon isotope composition is used to investigate the dependence between ozone and VOC or NOx mixing ratios at a rural site in Ontario, Canada, during fall and winter. The results show that under these conditions the variability in VOC mixing ratios is predominantly a result of the varying impact of local emissions and not a result of changes in the extent of atmospheric processing. This explains why the mixing ratio of ozone shows no systematic dependence on the mixing ratios of VOCs or NOx in this environment and at this time of the year.

• 出版日期2015