Dynamics of the volatile organic substances associated with cyanobacteria and algae in a eutrophic shallow lake.

The volatile substances present in a eutrophic shallow lake were determined qualitatively and quantitatively during the growing season, allowing a first-time analysis of the dynamics of these compounds in a water body. The major compounds found were beta-cyclocitral, alpha-cyclocitral, beta-ionone, 1,3,3-trimethylcyclohexene, 2,2,6-trimethylcyclohexanone, 2,6,6-trimethylcyclohex-2-en-1-one, eucalyptol, geosmin, two argosmin isomers, pent-1-en-3-ol, pent-1-en-3-one, heptadec-1-ene, heptadec-cis 5-ene, heptadeca-1, cis 8-diene, decanal, and hexanal. Most of the substances have not been detected before in natural waters. The occurrence of geosmin, the argosmin isomers, heptadec-cis 5-ene, and an unknown sesquiterpene could clearly be correlated with the appearance of Aphanizomenon gracile, as could the occurrence of beta-cyclocitral with the appearance of Microcystis wesenbergii. The data presented indicate that a rapid metabolism or the elimination of these compounds occurs in lake water.