Volatile organic compounds from leaves litter Valery Isidorov a, * , Maria Jdanova b a Chemical Institute of Białystok University, 15-443 Białystok, Poland b Chemical Department of St. Petersburg University, 198904 St. Petersburg, Russia Received 19 February 2001; received in revised form 23 August 2001; accepted 5 February 2002 Abstract Qualitative composition of volatile emissions of litter of five species of deciduous trees was investigated by GC-MS. The list of identified substances contains more than 70 organic compounds of various classes. It was established that the composition of components emitted by the litter into the gas phase greatly differs from that of essential oils extracted by hydrodistillation from turned leaves collected from trees during fall. It is suggested that most compounds found in litter emissions are products of vital activity of microorganisms decomposing it. The reported data indicate that after the vegetative period is over the decomposition processes of litter are important seasonal sources of reactive organic compounds under the forest canopy. Ó 2002 Published by Elsevier Science Ltd. Keywords: VOCs; Leaves; GC-MS; Decomposition 1. Introduction In the last decades, specialists in the atmospheric sciences paid much attention to biogenic emissions of volatile organic compounds (VOCs) from higher plants. This is due to the fact that the vegetation of continents is the main source of organic carbon in the atmosphere on the global scale. According to the present evaluations (Isidorov, 1990; Guenther et al., 1995), it annually emits into the atmosphere 1150–1500 Tg of VOCs capable of being actively included in oxidation processes. In air polluted with anthropogenic nitrogen oxides, under fa- vourable meteorological conditions these processes can lead to the formation of great amounts of ozone and other photooxidants (Fuentes et al., 2000) and to the generation of submicron aerosol particles (M€akel€a et al., 1997; Leaithch et al., 1999). To date, attention has focused on VOCs emission by leaves and needles of living plants. However, in our opinion, leaves litter can be a potentially important VOCs source. For land ecosystems, the litter mass is estimated to be about 50  10 15 gy 1 (Zavarzin, 1984). These organic material undergo microbiological decom- position. The intensity of this process is profoundly af- fected by external conditions, mainly by temperature and humidity. In rain tropical forests almost complete litter mineralization occurs rapidly, whereas in boreal forests it takes place slowly, and in soils of this belt organic carbon is accumulated. So far, there is no clear picture of litter microbiolog- ical decomposition. Still less is known about the decom- position of dead roots in soil. We know that fungi are the main group of organisms decomposing litter and that CO 2 , organic acids, and humus compounds are the dominant oxidation products (Babich and Stotzky, 1974). On the other hand, it has been found long ago that anaerobic and aerobic soil microorganisms (bacte- ria, fungi and yeast) grown on various nutritive arti- ficial media emit a broad range of VOCs into the gas phase. They include alkanes, alkenes, isoprene, terpenes, alcohols, carbonyl compounds, as well as sulfur-, nitro- gen-, and halogen-containing hydrocarbon derivatives Chemosphere 48 (2002) 975–979 www.elsevier.com/locate/chemosphere * Corresponding author. E-mail address: isidorov@uwb.edu.pl (V. Isidorov). 0045-6535/02/$ - see front matter Ó 2002 Published by Elsevier Science Ltd. PII:S0045-6535(02)00074-7