Laboratory and field measurements of enantiomeric monoterpene emissions as a function of chemotype, light and temperature

Abstract

Abstract. Plants emit significant amounts of monoterpenes into the earth's atmosphere, where they react rapidly to form a multitude of gas phase species and particles. Many monoterpenes exist in mirror-image forms or enantiomers. In this study the enantiomeric monoterpene profile for several representative plants (Quercus ilex L., Rosmarinus officinalis L., and Pinus halepensis Mill.) was investigated as a function of chemotype, light and temperature both in the laboratory and in the field. Analysis of enantiomeric monoterpenes from 19 Quercus ilex individuals from Southern France and Spain revealed four regiospecific chemotypes (genetically fixed emission patterns). In agreement with previous work, only Quercus ilex emissions increased strongly with light. However, for all three plant species no consistent enantiomeric variation was observed as a function of light, and the enantiomeric ratio of α-pinene was found to vary by less than 20 % from 100 and 1000 µmol m −2 s −1 PAR (photosynthetically active radiation). The rate of monoterpene emission increased with temperature from all three plant species, but little variation in the enantiomeric distribution of α-pinene was observed with temperature. There was more enantiomeric variability between individuals of the same species than could be induced by either light or temperature. Field measurements of α-pinene enantiomer mixing ratios in the air, taken at a Quercus ilex forest in Southern France, and several other previously reported field enantiomeric ratio diel cycle profiles are compared. All show smoothly varying diel cycles (some positive and some negative) even over changing wind directions. This is surprising in comparison with variations of enantiomeric emission patterns shown by individuals of the same species.

Isoprenoid emission response to changing light conditions of English oak, European beech and Norway spruce

“…The average A n rates for early spruce and late spruce were between 4.3 and 12.1 and between 3.6 and 12 µmol CO 2 m −2 s −1 respectively, whilst the G S rates ranged between 400 and 1200 mmol H 2 O m −2 s −1 for early spruce and between 300 and 1000 mmol H 2 O m −2 s −1 for late spruce. These values are in range or slightly higher than reported in other studies (Le Thiec et al, 1994;Roberntz and Stockfors, 1998;Špunda et al, 2005). Early spruce 1 and late spruce 2 behaved in a similar fashion as European beech with a tendency to stabilize their A n and G S rates at a light level of 500 µmol m −2 s −1 , indicating some shade adaptation of the selected needle twigs.…”

The Tree Drought Emission MONitor (Tree DEMON), an innovative system for assessing biogenic volatile organic compounds emission from plants

“…The regulation of environmental conditions in the chambers described is not as fast as for a small leaf cuvette (for instance [32, 50, 70, 71]), since air exchange rates of the chambers are smaller. Thus, the larger volume chambers are not very well suited to conduct experiments requiring fast (in the order of seconds) environmental changes.…”

Intense Vibronic Modulation of the Chiral Photoelectron Angular Distribution Generated by Photoionization of Limonene Enantiomers with Circularly Polarized Synchrotron Radiation

“…The monoterpene isomers, C 10 H 16 , are prominent amongst biogenic emissions of volatile compounds (BVOCs), and of these limonene is arguably the most frequently encountered. While clearly associated with citrus fruits, limonene is emitted from many plant species, including forestation and even the marine ecosphere . Limonene is one of the most frequently cited examples of a chiral molecule whose perceived odour depends upon the specific enantiomer sampled, and the varying enantiomeric distribution of biogenic limonene with plant type and environment is emerging to be of significant interest .…”