Specifics of Phase Equilibria Studies in the Multinary Aqueous Systems

Фазовые диаграммы и данные по фазовым равновесиям в многокомпонентных системах лежат в основе технологических схем переработки рассолов природного и техногенного происхождения, проектирования процессов получения, разделения и очистки неорганических веществ. Поэтому разработку новых технологий, усовершенствование технологических процессов необходимо начинать с изученя соответствующих систем и построения фазовых диаграмм. Эффективность изучения фазовых равновесий в многокомпонентных водно-солевых системах оптимизированным методом сечений показана на примере пятикомпонентной системы CO(NH2)2 – NH4Cl – (NH4)2SO4 – NH4H2PO4 – H2O при 25 °C. Оптимизированный метод сечений позволяет определять составы равновесных фаз без выделения их из раствора и последующего физико-химического анализа. В результате образования между карбамидом и хлоридом аммония химического соединения NH4Cl·CO(NH2)2 в системе появляются две нонвариантные области – эвтоническая и перитоническая. В работе описаны особенности прогнозирования составов двух нонвариантных точек, экспериментального определения составов на гиперплоскостях нонвариантных областей для расчета по ним составов равновесных жидких и твердых фаз. Показана эффективность алгоритма прогнозирования нонвариантных составов в системе. Описана методология планирования исследования линий моновариантного равновесия и поверхности кристаллизации индивидуальных солей. По экспериментальным данным построена проекция фазовой диаграммы на солевое основание системыThe data of phase equilibria and phase diagrams have an important significance to guide the development and utilization of brine-mineral resources, design process of obtain, separation and purification of inorganic salts, and provide a theoretical basis for understanding the recovery of rare earth elements, whether from the environment or the economy. Therefore, the phase diagram determination of the corresponding systems is essential for establishment of the optimal temperature-concentration conditions of the process of crystallization. The efficiency of the investigation of the solid-liquid equilibria in quinary system CO(NH2)2 – NH4Cl – (NH4)2SO4 – NH4H2PO4 – H2O at 25 °C by the optimized sections method was shown. The method is allowed to determine the compositions of equilibrium solid phases without isolating them from liquid in the systems differently complexity. As a result of the formation of one complex salt NH4Cl·CO(NH2)2 between urea and ammonium chloride the quinary system has two invariant regions – eutonic and peritonic. In this study, the specifics of predicting the compositions of two invariant points, experimental determination of the compositions on the hyperplanes of invariant regions for computation of the compositions of equilibrium liquid and solid phases were considered. The efficiency of the algorithm for predicting the compositions of invariant points in the system was proved. The methodology of experimental design in studies of univariant curves and salt crystallization surfaces was described. According to the experimental data the phase diagram projection on the salt base of the system was constructe

Chronicles of nature calendar, a long-term and large-scale multitaxon database on phenology

We present an extensive, large-scale, long-term and multitaxon database on phenological and climatic variation, involving 506,186 observation dates acquired in 471 localities in Russian Federation, Ukraine, Uzbekistan, Belarus and Kyrgyzstan. The data cover the period 1890-2018, with 96% of the data being from 1960 onwards. The database is rich in plants, birds and climatic events, but also includes insects, amphibians, reptiles and fungi. The database includes multiple events per species, such as the onset days of leaf unfolding and leaf fall for plants, and the days for first spring and last autumn occurrences for birds. The data were acquired using standardized methods by permanent staff of national parks and nature reserves (87% of the data) and members of a phenological observation network (13% of the data). The database is valuable for exploring how species respond in their phenology to climate change. Large-scale analyses of spatial variation in phenological response can help to better predict the consequences of species and community responses to climate change.Peer reviewe

Phenological shifts of abiotic events, producers and consumers across a continent

Ongoing climate change can shift organism phenology in ways that vary depending on species, habitats and climate factors studied. To probe for large-scale patterns in associated phenological change, we use 70,709 observations from six decades of systematic monitoring across the former Union of Soviet Socialist Republics. Among 110 phenological events related to plants, birds, insects, amphibians and fungi, we find a mosaic of change, defying simple predictions of earlier springs, later autumns and stronger changes at higher latitudes and elevations. Site mean temperature emerged as a strong predictor of local phenology, but the magnitude and direction of change varied with trophic level and the relative timing of an event. Beyond temperature-associated variation, we uncover high variation among both sites and years, with some sites being characterized by disproportionately long seasons and others by short ones. Our findings emphasize concerns regarding ecosystem integrity and highlight the difficulty of predicting climate change outcomes. The authors use systematic monitoring across the former USSR to investigate phenological changes across taxa. The long-term mean temperature of a site emerged as a strong predictor of phenological change, with further imprints of trophic level, event timing, site, year and biotic interactions.Peer reviewe

Differences in spatial versus temporal reaction norms for spring and autumn phenological events

For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the environmental effects on timing (cogradient variation) or attenuate the effects (countergradient variation). To resolve spatial and seasonal variation in species' response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms tend to accentuate responses in spring (cogradient variation) and attenuate them in autumn (countergradient variation). As a result, among-population variation in the timing of events is greater in spring and less in autumn than if all populations followed the same reaction norm regardless of location. Despite such signs of local adaptation, overall phenotypic plasticity was not sufficient for phenological events to keep exact pace with their cues-the earlier the year, the more did the timing of the phenological event lag behind the timing of the cue. Overall, these patterns suggest that differences in the spatial versus temporal reaction norms will affect species' response to climate change in opposite ways in spring and autumn