Atmospheric chemistry

Atmospheric radical chemistry revisited, Vaida, V., Science, vol. 353, issue 6300, pp. 650, Published by the AAAS, 12 August 2016.

Chapter 2 emphasizes the importance of various types of atmospheric reactions and the significant role played by solar radiation in driving many of these. This paper examines sunlight’s role as the largest energy source for Earth and agrees that this helps determine many aspects of Earth’s atmospheric chemistry and climate. Much like our discussions, this paper acknowledges that photolysis of ozone leads to the formation of hydroxyl radicals, which are involved in most oxidative processes in the environment. However, the author details research on an alternative oxidation processes, discussing how others have shown i) that direct photolysis of a fatty acid at an air-water interface leads to the formation of oxidized products in the gas phase, and ii) indirect photolysis of organic molecules must also be considered, potentially unlocking new radical reactions initiated by absorption of sunlight. Clearly our simplified view of these atmospheric processes have a more complicated story.

The hydroxyl radical

Small interannual variability of global atmospheric hydroxyl, Montzka, S.A., M. Krol, E. Dlugokencky, B. Hall, P. Jockel, and J. Lelieveld, Science, (2011) 67-69 (Published by the AAAS, January 2011).

We emphasize the central importance of the hydroxyl radical in atmospheric chemistry in Chapter 2 and again later in Chapter 3. This paper examines the commonly-used method of determining global averages of this radical. By taking into account appropriate modifications it is concluded that, while there are local perturbations in the mixing ratio of hydroxyl, on a global scale its concentration is well buffered and relatively constant from year to year.