Diamines,
such as 1,3-diaminopropane (Dap), 1,4-diaminobutane (putrescine,
or Put), and 1,5-diaminopentane (cadaverine), are essential organic
bases for plants. Such “biogenic diamines” are abundantly
present in oak tree flowers and are emitted into the atmosphere. We
sampled atmospheric diamines in a typical broadleaf tree forest and
chestnut grove during blossom season and carried out a chromatography-mass
spectrometry analysis. Amide derivatives of Dap and Put, 3-aminopropanamide
and 4-aminobutanamide, respectively, were found in higher atmospheric
concentrations than their source diamine. Because their concentrations
in oak tree flowers were very low, we deduced that these aminoamides
were produced after Dap and Put, respectively, were released into
the atmosphere. Time series of biogenic diamine and aminoamide concentrations
showed evidence of diurnal variations. Concentrations were lower during
daytime in sunny conditions, suggesting relatively fast photochemical
decomposition. Biogenic diamines and aminoamides bond more easily
than monoamines with water vapor and sulfuric acid in the atmosphere.
Biogenic diamines and aminoamides may play a role in the formation
of new particles and biogenic secondary organic aerosols in the forest
atmosphere during spring and early summer.