Organic aerosols influence the world’s climate in several ways. They can serve, for example, as cloud condensation nuclei as they adsorb water on their surface, causing the condensation of air moisture to small water droplets and thus the development of mist.
The aerosols are formed by mutual adsorption of so-called secondary organic compounds. These are the non-volatile products of atmospheric oxidation reactions of volatile hydrocarbons emitted by tropical plants. Until now, it has been assumed that only these organic compounds take part in the aerosol formation process. However, the mechanism of its initial step, when secondary organic compounds start to adsorb one another, remained unclear.
Ulrich Pöschl, Christopher Pöhlker and colleagues, Max Planck Insitute for Chemistry, Mainz, Germany, used scanning transmission X-ray microscopy with near edge X-ray absorption fine structure analysis, scanning electron microscopy, and secondary ion mass spectrometry to analyze the structure and composition of organic aerosols in the Amazonian rainforest. Among all the substances found in the aerosol particles, potassium was always present. Therefore, the research team concluded that potassium salts might be responsible for the initialization of the mutual adsorption process of non-volatile organic compounds, acting as seeds for the aerosol formation. This indicates a close relationship between the rainforest’s biosphere and its climate, as the potassium salts are released by tropical plants and particularly fungi.
- Biogenic Potassium Salt Particles as Seeds for Secondary Organic Aerosol in the Amazon,
C. Pöhlker, K. T. Wiedemann, B. Sinha, M. Shiraiwa, S. S. Gunthe, M. Smith, H. Su, P. Artaxo, Q. Chen, Y. Cheng, W. Elbert, M. K. Gilles, A. L. D. Kilcoyne, R. C. Moffet, M. Weigand, S. T. Martin, U. Pöschl, M. O. Andreae,
Science 2012, 337 (6098), 1075–1078.