التفاعل الكيميائى وجهد النقل الطويل للمواد الهيدروكربونية متعددة الحلقات - مقالة مرجعية
2013
Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised toxicity
and especially due to the carcinogenic hazard which they present. PAHs are semi-volatile and therefore
partition between vapour and condensed phases in the atmosphere and both the vapour and particulate
forms undergo chemical reactions. This article briefly reviews the current understanding of vapour–particle
partitioning of PAHs and the PAH deposition processes, and in greater detail, their chemical reactions.
PAHs are reactive towards a number of atmospheric oxidants, most notably the hydroxyl radical, ozone,
the nitrate radical (NO3) and nitrogen dioxide. Rate coefficient data are reviewed for reactions of lower
molecular weight PAH vapour with these species as well as for heterogeneous reactions of higher
molecular weight compounds. Whereas the data for reactions of the 2–3-ring PAH vapour are quite
extensive and generally consistent, such data are mostly lacking for the 4-ring PAHs and the heterogeneous
rate data (5 and more rings), which are dependent on the substrate type and reaction conditions, are
less comprehensive. The atmospheric reactions of PAH lead to the formation of oxy and nitro derivatives,
reviewed here, too. Finally, the capacity of PAHs for long range transport and the results of numerical
model studies are described. Research needs are identified.
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