Articles | Volume 16, issue 19
Research article
14 Oct 2016
Research article |  | 14 Oct 2016

Observation of new particle formation and measurement of sulfuric acid, ammonia, amines and highly oxidized organic molecules at a rural site in central Germany

Andreas Kürten, Anton Bergen, Martin Heinritzi, Markus Leiminger, Verena Lorenz, Felix Piel, Mario Simon, Robert Sitals, Andrea C. Wagner, and Joachim Curtius

Abstract. The exact mechanisms for new particle formation (NPF) under different boundary layer conditions are not known yet. One important question is whether amines and sulfuric acid lead to efficient NPF in the atmosphere. Furthermore, it is not clear to what extent highly oxidized organic molecules (HOMs) are involved in NPF. We conducted field measurements at a rural site in central Germany in the proximity of three larger dairy farms to investigate whether there is a connection between NPF and the presence of amines and/or ammonia due to the local emissions from the farms. Comprehensive measurements using a nitrate chemical ionization–atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer, a proton-transfer-reaction mass spectrometer (PTR-MS), particle counters and differential mobility analyzers (DMAs), as well as measurements of trace gases and meteorological parameters, were performed. We demonstrate here that the nitrate CI-APi-TOF is suitable for sensitive measurements of sulfuric acid, amines, a nitrosamine, ammonia, iodic acid and HOMs. NPF was found to correlate with sulfuric acid, while an anti-correlation with RH, amines and ammonia is observed. The anti-correlation between NPF and amines could be due to the efficient uptake of these compounds by nucleating clusters and small particles. Much higher HOM dimer (C19/C20 compounds) concentrations during the night than during the day indicate that these HOMs do not efficiently self-nucleate as no nighttime NPF is observed. Observed iodic acid probably originates from an iodine-containing reservoir substance, but the iodine signals are very likely too low to have a significant effect on NPF.

Short summary
Field measurements were conducted at a rural site in central Germany close to dairy farms to investigate if there is a connection between new particle formation and the presence of amines. A variety of trace gases were measured in addition to amines, like sulfuric acid, ammonia and highly oxygenated organic molecules (HOM). The results indicate that amines are very likely involved in the growth of aerosol particles and probably also in the nucleation process, although HOM could be relevant, too.
Final-revised paper