The level of limnological knowledge of the European part of Russia (EPR) and the current state of the lake ecosystems located on the territory are analyzed basing on the analysis of scientific and reference publications. The emphasis is made on the poor knowledge of water bodies of the regions of active industrial development. First of all, this is the North-East of the EPR, where the oil and gas complex is actively developing. Simplified arctic ecosystems are characterized by increased vulnerability to various impacts, which raises the concerns about health of the population living in these regions. Significant problems are also observed at the lakes of the center and south of the EPR, where their number is initially small, and the anthropogenic transformation of the territory causes the gradual replacement of the natural bodies by artificial ones, with the accompanying loss of biodiversity. It is concluded that there is a need to develop a special program aimed at studying mechanisms of the functioning of northern lake ecosystems, as well as adopting the unified monitoring program for lakes that have received a special conservational status.

Coastalisation - the concentration of population and economic activities on the coasts of the World Ocean - has been investigated since the mid 19th century. Coastalisation studies focusing on the Baltic region do not date back a long time. However, the region per se has been studied extensively since the 1990s when it underwent dramatic geopolitical changes and became a hub for integration processes. Researchers have established how the vicinity of the sea affects parts of the Baltic Sea that differ in environmental and socioeconomic conditions and belong to different states. However, it has not been examined how coastalisation influences networks of coastal cities. This article studies the spatial features of the emergence and development of coastal city networks. The authors use Eurostat data, national statistics of the Baltic region states, research literature, and coastal city websites. The study uses mapping and statistical analysis. The findings may be used in spatial planning in the Baltic region and in university programmes.

Sustainable social and economic development of cities is a complex, multifactorial phenomenon that has different dimensions and evaluation criteria. One of the simplest and most accessible indicators of the situation in the economy and social sphere is the population dynamics. Authors investigate the influence of 2014-2016 years Russian economic crisis phenomena on the urban population dynamics in Leningrad region. Since the late 1980 s the cities of the Leningrad region developed in a different way: in some cities population was steadily declining, in others it was growing, and in some cities stagnation was observed. These differences preserved to the present time, but the population growth and decline rates (caused largely by migration processes) vary considerably, depending on economic situation. As a result of the research it was revealed that during crisis phenomena of 2014-2016 years еру demographic trend change was not typical for all the cities. Authors identify several types of urban settlements according to their population dynamics pattern in 2011-2017 years and offer explanation for the differences in cities resilience to crisis phenomena.

The lava flows of XX-XXI centuries at six volcanic areas of Kamchatka are considered. Lava flows and fields had overlapped area of about 125 km², most of the suffered territories had mountain and high-mountain barrens, formed by old lava flows and scoria areas of past eruptions (totally about 77 km²). These flows had destroyed forest at area of about 28 km² (half of the forest was coniferous and the other half was forest of Erman's birch), as well as about 20 km² of subalpine thickets of alder, Japanese stone pine and meadows. The largest effusions of basaltic lavas have occurred in the Tolbachik Dol volcano area (totaling 85 km²), and on the slopes of the Klyuchevskoy volcano (35 km²). Andesite-basalt flows of Karymsky and Kizimen volcanoes destroyed the volcanic ecosystems of the slopes in relatively small areas. Short andesite flows at the active volcano domes of Shiveluch and Bezymianny volcanoes caused only mediated devastation, often at a considerable distance from the eruptive centers (through the collapse of a dome and forming of pyroclastic flows). Forest fires during the eruptions were not noted, but potentially they may be possible in areas of coniferous forest. Restoring of forest vegetation takes place during an extremely long period (up to 2000 years), ash falls can speed up or slow down a succession during this period.

The results of studies of the effect of changes in the regional climate on the dynamics of the thermal regime of two small boreal lakes with different types of mixing during the open water period according to the data of long-term observations are given in the article. The main attention is paid to the stage of spring mixing (including spring under-ice convection and the stage of homothermy after breaking of ice), and revealing its role in the development of the thermal regime of lakes at subsequent stages of the annual cycle. It is shown that the spring under-ice convection began on lakes earlier and lasted longer in years with abnormally high winter and spring air temperatures than in years with temperatures of these months close to the climatic norm. This could provoke the formation of direct stratification by the end of the ice period and the disappearance of the stage of homothermy after ice-break. The duration of the spring homothermia phase is the most critical for dimictic lakes, since it affects the summer temperature of the hypolimnion and can therefore determine both the thermal and gas regimes at subsequent stages of the annual cycle. The obtained results allow us to conclude that, against the background of anomalously warm winter and spring months, polymictic lakes can acquire features of dimictic ones, leaving stably stratified after the melting of ice, and losing the stage of spring homothermy. Reduction of the ice-period on dimictic lakes due to earlier ice-off may lead to both a decrease and an increase in the duration of summer stratification, depending on the weather conditions of late spring and early summer.

The article deals with the dynamics of socio-economic development of the 75 cities-administrative centres of Russian regions. The main objective of the study is to test the author's methodology that defines and classifies the trajectories of change in the relative position of the city in the studied sample in each year of the period. Unlike common schema analysis when comparing the situation at the beginning and at the end of the period, the authors study the changes for 11 years on a year-by-year basis, in other words, trajectories of change in the relative position of the object in the studied sample. The study and comparison of the trajectories allows: a) to see the inflection points-the years in which the city's development was slowed or accelerated to further identifying the factors that influence the trajectory; b) suggest the base to group cities by the type of trajectory dynamics. The technique involves the calculation of index of dynamics of city development based on the integration of nine indicators and building of vector ranks. In addition, sampling characteristics of minimum and maximum values and coefficients of variation are calculated for each of nine primary indicators. The cities are grouped according to the trajectory of the vectors ranks dynamics. The group of cities and towns steadily growing faster than others, consistently lagging and path-changing ones are identified. Hypotheses about the causes of the acceleration or deceleration of individual cities are presented. No meaningful connection between acceleration of the development and elaboration of official strategies was identified.