Свойства на-несенных на θ-Al2O3 гетерополисоединений в процессе улав-ливания NOх по данным ИК- спектроскопии in situ

It was shown that carrying a small (up to 1%) amount of a heteropoly compound increases the adsorption of NOx as compared to the original carrier. The increase in adsorption is due to the oxidation of NO to NO2 on the carried heteropoly compound. The main adsorption factors are nitrite and nitrate complexes. Their place of localization is the carrier. As temperature increases, the complexes change to nitrates. The presence of ions of varying valencies in the composition of the Kegin anion reduces the strength of the bond of the nitrate complexes with the surface. The ions that are not in the Kegin anion increase the bond strength. The change in the strength of the bond of nitrates with the surface of the carrier is owned to the carrier modification, which results from disintegration of a part of the carried heteropoly compound.С использованием ИК-спектроскопии in situ в режиме термодесорбции проведено исследование механизма активации оксидов азота на массивных гетерополисоединениях, а также состава адсорбционных комплексов, места их локализации, стабильности, механизма взаимных превращений на нанесенных на θ-Al2O3 гетерополисоединениях. Показано, что нанесение небольшого (до 1%) количества гетерополисоединения увеличивает адсорбцию NOх по сравнению с чистым носителем. Увеличение адсорбции связано с окислением NO до NO2 на нанесенном гетерополисоединении. Основными формами адсорбции являются нитритные и нитратные комплексы, которые локализуются на носителе. С повышением температуры нитритные комплексы превращаются в нитратные. Присутствие ионов переменной валентности в составе аниона Кегина уменьшает прочность связи нитратных комплексов с поверхностью; ионы, не входящие в состав аниона Кегина, увеличивают прочность связи. Изменение прочности связи нитратов с поверхностью носителя происходит в результате модифицирования носителя за счет деструкции части нанесенного гетерополисоединения

Patterned-ground facilitates shrub expansion in Low Arctic tundra

Recent expansion of tall shrubs in Low Arctic tundra is widely seen as a response to climate warming, but shrubification is not occurring as a simple function of regional climate trends. We show that establishment of tall alder ( Alnus ) is strongly facilitated by small, widely distributed cryogenic disturbances associated with patterned-ground landscapes. We identified expanding and newly established shrub stands at two northwest Siberian sites and observed that virtually all new shrubs occurred on bare microsites (‘circles’) that were disturbed by frost-heave. Frost-heave associated with circles is a widespread, annual phenomenon that maintains mosaics of mineral seedbeds with warm soils and few competitors that are immediately available to shrubs during favorable climatic periods. Circle facilitation of alder recruitment also plausibly explains the development of shrublands in which alders are regularly spaced. We conclude that alder abundance and extent have increased rapidly in the northwest Siberian Low Arctic since at least the mid-20th century, despite a lack of summer warming in recent decades. Our results are consistent with findings in the North American Arctic which emphasize that the responsiveness of Low Arctic landscapes to climate change is largely determined by the frequency and extent of disturbance processes that create mineral-rich seedbeds favorable for tall shrub recruitment. Northwest Siberia has high potential for continued expansion of tall shrubs and concomitant changes to ecosystem function, due to the widespread distribution of patterned-ground landscapes

Properties of heteropoly compounds carried on θ-Al₂O₃ in the capturing of NOx using infra red spectroscopy (in situ)

It was shown that carrying a small (up to 1%) amount of a heteropoly compound increases the adsorption of NOx as compared to the original carrier. The increase in adsorption is due to the oxidation of NO to NO2 on the carried heteropoly compound. The main adsorption factors are nitrite and nitrate complexes. Their place of localization is the carrier. As temperature increases, the complexes change to nitrates. The presence of ions of varying valencies in the composition of the Kegin anion reduces the strength of the bond of the nitrate complexes with the surface. The ions that are not in the Kegin anion increase the bond strength. The change in the strength of the bond of nitrates with the surface of the carrier is owned to the carrier modification, which results from disintegration of a part of the carried heteropoly compound

The Input of the Climatic Factors in the Temperature Regime of Soils of Discontinuous Permafrost of Northern Taiga of Western Siberia

The results of the four-year study of the temperature regime of soils of three common landscapes of northern taiga in Western Siberia, located in the area of discontinuous permafrost, are presented. The soils of lumpy peatlands are characterized by mild permafrost annual regime with very cold summer and moderately cold winter. Temperature regime of the forest soils may be characterized as cold long-time seasonally freezing mild with very cold summer and moderately cold winter. The soils of the investigated region are functioning in conditions of the narrow range of temperatures: at the depth of 20 cm for the soils of all of the landscapes, the temperatures vary within the range of -2.5 to 0°С. This occurs due to their high moisture, low thermal conductivity, specificities of snow cover regime and the freezing effect of permafrost rocks. Annual temperature soil indices are characterized by the weak correlation to the mean annual specificities of air temperature regime. We discovered the direct correlation of annual soil temperature regime and the dynamics of the snow cover (with average and maximal thickness, and thawing date), and with winter N-factor (surface temperature index), and accumulative positive temperatures. Since isolating activity of the vegetation is significantly lower than that of snow (summer N- factors 0.7-0.9), annual fluctuations of summer air temperatures will significantly affect the temperature regime of soils and geo-cryologic situation of the region in general