B. G. Ageev

Variation of H 2 O, CO 2 , and CO 2 Isotope Composition in Tree Rings of Siberian Stone Pine

The experimental measurements of H2O, CO2, and the carbon isotope content of CO2, vacuum-desorbed from tree rings of the Siberian stone pine disc, have been obtained. It is shown that: 1) certain cyclicity exists in annual trends of H2O and CO2; 2) the amplitude of CO2 cycles has markedly risen after 1960; 3) the annual trend of the CO2 concentration in the rings correlates with an increase in atmospheric CO2 concentration; 4) the carbon isotope content varies with the variation of CO2 concentration in a sample.

Variations in gas components and total pressure in stem and root disc wood of conifer species

The content of CO2 and H2O in vacuum-extracted tree-ring wood of stem and root discs of certain conifer species was measured. Annual distributions of these gas components were found to exhibit cyclic behavior. Moreover, distinct cyclicity was also revealed in interannual variations of the total pressure of the vacuum-extracted tree-ring gas samples. It may be safely assumed that diffusion of stem CO2 into the atmosphere will show the same periodic variability. Two hypotheses about the origin of the cyclicity in the treering CO2 distributions are examined.

Variations and trends in CO 2 and H 2 O content in coniferous tree-rings

The experimental values of the variation in the CO2 and H2O content in tree-rings of some conifers from regions with different climate conditions have been obtained. These data are compared with tree-ring widths; some conclusions are made about the climatic response in the annual CO2 and H2O distributions. The hypothesis is proposed that the long-term cyclicity found in the annual CO2 distribution over tree rings is a response of trees to environmental changes.

A trend of the CO2 concentration in tree rings and the atmospheric CO2

Several suppositions about the interpretation of the CO2 content measurements in the rings of old discs of tree stems are put forward. In particular, it is supposed that the trend in the annual CO2 content detected in the rings is related to the rising concentration of the atmospheric CO2.

Dark respiration under low pressure and increased ethylene

Responses of plants seedlings to hypobaria (reduced pressure of air) exposure (up to 8 kPa) and exogenously applied ethylene (10 -4 , 10 -5 , 10 -6 kPa) was studied using a gasometric system based on CO 2 -laser photoacoustic spectrometer. The increase of O 2 -evolution (in the dark) by pea (Pisum sativum L.), wheat (Triticum aestivum L.), maize (Zea mays L.), barley (Hordeum vulgare L.) and pine seedlings (Pinus sylvestris L.) was revealed. Some differences in dynamics of CO 2 -evolution and signal magnitudes are probably stipulated by the objects specificity. The alcohol-dehydrogenase, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, phosphoenolpyruvate carboxylase activity and contents of malate, pyruvate and lactate were studied in pea leaves. It was shown that an anaerobic metabolism increases with time and also when the air pressure is decreased. An increase of CO 2 -evolution from ethylene-treated pea seedlings and alcohol-dehydrogenase activation were observed.

Certain features of gas emission from the wood of annual rings of conifers

Results of our studies of gas content in rings of tree discs have shown that a significant part of the CO2 generated by cell respiration remains in tree stems. The content of this CO2 exceeds the atmospheric CO2 in most cases and forms the distribution over tree rings. In our investigations, we first used photoacoustic gas analysis. In this work, we discuss certain features of the chronologies (year-to-year distribution) of gas samples.

Design of eye-safe YAG:TmCrHo pulsed laser and study of its radiation absorption by molecular gases and air

Abstract The design of a frequency tunable pulsed YAG:TmCrHo-laser is described. The laser line half-width is less than 0.09 cm −1 . The tuning of laser frequency is achieved by using the temperature controlled quartz Fabry-Perot interferometer as an output mirror. The determined width of the tuning spectral interval near 2.08 μm is of about 2 cm −1 . The absorption of YAG:TmCrHo-laser radiation by CO 2 , H 2 O, and air within the interval was studied using photo-acoustic and spectrophotometric methods.

Measurements of the carbon dioxide concentration in silicon dioxide nanopores

Measurement results on the concentration of carbon dioxide, adsorbed by nanopores of silicon dioxide, are presented. The measurements were conducted by the laser photoacoustic gas-analysis method. The magnitude found corresponds well to the concentration value found with the help of the standard vacuum technique.

Laser gas-analyzers for studying kinetics of gas-exchange between vegetation biosystems and atmosphere

Specifications and examples of application of laser gas-analyzers of near- and mid-infrared ranges for diagnostics of greenhouse gases (CO2, C2H4, and CH4) emission by vegetation biosystems both under standard conditions and under impacts of natural and anthropogenic stresses are considered in the report. The gas-analyzer complex includes: 1) gas-analyzer with a multipass absorption cell based on the frequency-tunable diode laser (1600-1650 nm) for measuring sub-background methane concentrations (≤ 20 ppbV); 2) gas-analyzer based on the wave-guide CO2-laser equipped with the intracavity acoustic detector capable of fast frequency scanning in the 9 and 10 μm generation bands and having the ethylene-sensitivity better than 1 ppbV. The technology of measurements of gas emission by plant stripped leaves and coniferous needles is described and the measurements of CO2 and CH4 emissions are presented.

Variations of Residual CO 2 and Pressure in Conifer Woody Roots

In continuation of works on the determination of cyclic tree-stem CO2 efflux, vacuum-extracted gas samples of large woody roots of Siberian stone pine and Scots pine are studied. Laser photoacoustic gas analysis was used to obtain chronologies of CO2 and total pressure of gas components in root rings. Spectral and cross-spectral analyses reveal the cyclic character of variations in the chronologies. Such a behavior of the total pressure and CO2 content in large roots can testify to possible cyclic diffusion of CO2 from the roots into soil and then into the atmosphere, which can be considered as a new feature of autotroph respiration. An attempt is made to analyze results of some previous work on a similar subject based on cyclic CO2 efflux from large roots.