nitric acid breaks down into a nitrous oxide and a hydroxyl radical
HNO3→OH+NO2
an organic radical is formed when hydrogen is extracted by the hydroxyl
radical
R–H+OH→R+H2O
the organic radical then reacts with nitrogen oxide to form nitrate
R+NO2→R–NO2
nitrite rather than nitrate may be formed
R+NO2→R–O–N–O
The reactions described would account for the presence of nitrogen compounds but
do not explain the other reactions taking place.