RESUMO
This article presents measurements of the piezoelectric modulus d 11 of a single crystal of lanthanum gallium silicate (LGS, La3Ga5SiO14). The piezoelectric modulus was measured by X-ray diffraction at angles close to backscattering. Experiments in such schemes are very sensitive to relative changes in the lattice constant in crystals caused by external influences (constant or alternating electric field, mechanical load, temperature change etc.). The development opportunity of the technique is shown, its applicability is evaluated and results of measurement of the LGS single-crystal piezo modulus by the method of diffraction of synchrotron radiation at angles near π are discussed.
RESUMO
For the first time were the results of studies on influence of main kinds of local anthropogenic factors on soil emission of biogenic greenhouse gases (CO2, CH4, and N2O) in permafrost ecosystems of Arctic and North-Boreal zones of the Russian Federation, and also of the Spitsbergen Archipelag summarized. Different types of land use can, depending on their manner, lead to significant enhancing or suppression of soil CO2 emission. On average, anthropogenic factors (AFs), acting in concert, favor the enhancement of local CO2 soil emission, promoting, at the same time, an increase in its dispersion. AFs directly influence the microbial-root respiration in soil, modify the soil itself, and indirectly affect important natural respiration regulators, phytomass reserves in particular, which makes them primary factors with relation to respiration pattern. AFs influence also the emission of other biogenic greenhouse gases (CH4 and N2O), though this influence can be exercised in different ways. Methane emission is mediated by degree of the territory drainage. However, in all studied cases, AFs have led to source reduction or sink intensification of this gas from the atmosphere. Unlike methane emission, N2O emission increased under the influence of AFs considered. As for the whole complex of AFs that impacts the carbon balance and fluxes of CO2 in cryogenic ecosystems, its role is expressed through the enhancement of soil respiration at the beginning of the cold season, when AFs are capable of soil emission increasing, at the level of meso-landscape, almost by 50%.
