While there is much meta going on and on and on and on, even at Rabett Run, Eli came across some interesting science in Science. As previously discussed here, the oxidative capacity of the atmosphere has remained constant, a bit of a shock as with the increasing injection of methane and various dirties (as in Asian brown cloud), somebunny might think that it would have fallen, as indeed the authors of the previously discussed paper did
However, a consistent, predictive understanding of the net response of [OH] on broad scales to such perturbations is lacking. For example, a range of negative [OH] feedbacks is calculated from changes in atmospheric methane abundance (3, 5–7).Which is why a new paper by Su and a list of co authors long enough for CERN, Uli Poeschl being the last but not least, is so interesting. The experiment was simple enough, they put some dirt into a tube and blew air through it, analyzing what came out. they found that nitrite (NO2-) converts to nitrous acid, HNO2, in the soil which desorbs into the atmosphere as HONO (yes atmospheric science folk pronounce it that way).
At this point Eli has to commit some chemistry. The first point, which is NOT taught in General Chemistry, or at least most GChem courses, is that molecules that you can buy are not reactive.
They are stable. In the case of organic or molecules consisting of non-metals, each atom is surrounded by a shared outer shell of eight electrons which makes them think they are noble gases, much as Chris Monckton thinks he is a Nobel prize winner, and they don't want to know different or associate with non-peers.
However there are some molecules with an odd number of electrons in the outer shell (so they can't have eight) called free radicals, and free radicals are very reactive because that odd electron is looking for a partner. In the atmosphere HO is the most important free radical and the one responsible for cleaning out all the hydrocarbons such as methane (chemistry at link).
the question being where the HO comes from.
The generic answer is in water aerosols where nitrogen dioxide has dissolved
H2O(aq) + 2 NO2(aq)= HNO3(aq) + HONO (g)
and the HONO absorbs a photon and falls apart into HO + NO but there is not enough of this process to explain the concentration of HO in the atmosphere, without significant ear waving. Su et al have added the red arrow below the line processes.
This appears to be catalyzed at low pH (acid conditions) and we know that agriculture is increasingly acidifying and fertilizing soils which is degrading water quality and increasing eutrophication. It may also have maintained the oxidative capacity of the atmosphere, leaving us lagomorphs with the choice of dirty air or dirty water