Composition of organic volatile compounds in the atmosphere of forest ecosystems as studied by gas chromatography
Cermak, J.; Novak, J.
Ekologia-CSSR 6(3): 251-264
Air samples from an open atmosphere of the forest ecosystem and from the atmosphere close to plant organs were analyzed for the content of organic volatile substances. The combination of the sorption enrichment techniques (trapping columns with Tenax GC, through which about 5 to 15 lines of air were sucked) and the gas chromatography with flame-ionization detection were used for analysis. The calculation of the individual analyte mass in the concentrate obtained was made through the interpretation of the chromatogram on the basis of previously known parameters of the used flame-ionization detector without direct calibration of individual analytes by the method described by Novak and Cermak (1986). Several tens of volatile organic substances were found in the analyzed air from the crown space of a mixed forest by the above mentioned method. The effective carbon numbers in these substances were about C4 to C12 (t.m.isoprene to dodecane) with boiling temperatures of about 30 to 230.degree. C. The concentration of individual substances was in units up to hundreds nanograms per cubic meter, the concentration of the whole mixture reached about 1 .mu.g m-3. It was found which substances were released from particular source namely from spruce (Picea abies (L.) Karst) needles (mostly monoterpenes were found there) and which of these substances changed their proportions in the mixture when needles were exposed to drought. The method described allows to take samples within time interval of any duration. The results obtained can be used for the assessment of a physiological state of trees in various space scales (from plant parts to landscape) and for the application in a row of ecological branches.