Biogenic Potassium Salt Particles as Seeds for Secondary Organic Aerosol in the Amazon

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.

Max Planck Society

Max Planck Society

Max Planck Graduate Center

Max Planck Graduate Center

Geocycles Cluster Mainz (Landesexzellenzcluster RheinlandPfalz)

Geocycles Cluster Mainz (Landesexzellenzcluster Rheinland-Pfalz)

European Community (PEGASOS) [FP7-265148]

European Community (PEGASOS)

Office of Science, Office of Basic Energy Sciences (BES), U.S. Department of Energy (DOE) [DE-FG02-08ER6452]

Office of Science, Office of Basic Energy Sciences (BES), U.S. Department of Energy (DOE)

U.S. NSF [0925467]

U.S. NSF

Office of Science, BES, of the U.S. DOE

Office of Science, BES, of the U.S. DOE [DE-AC02-05CH11231]