Methane emission from coal and associated strata samples

Summary This article discusses methods for providing a reliable forecast of the gas-dynamic behaviour of coal seams and adjacent strata. It shows that the ash content of carbonaceous materials determines their sorptive capacity (a universally applicable expression is presented for calculating the methane content of a sample) whilst the rate of methane desorption is a function of the degree of geological disturbance, i.e. the number and distribution of the macropores and fractures in the sample. This effect becomes less important as the sample ash content increases and effectively disappears above a certain value for high permeability materials.The quantity sorption-kinetic characteristic is shown to be a reliable means for quantifying methane emission behaviour. Large variations in coal sorption-kinetic characteristics are shown to occur over short distances as the geological structure of the seam changes, both vertically and horizontally. Consequently, sorption-kinetic characteristics may be used to predict the general level of methane emission from the seam and to quantify the risk of outburst inherent in disturbed areas of coal seams.     

Possibilities of the photoluminescence method for determining the oxygen concentration in the redox zone of the Black Sea in comparison with other methods

Different methods of measuring low oxygen concentrations were compared in July 2008 in the Black Sea: the conventional Winkler method, electrochemical sensors (membrane and membrane-free), and two modifications of photoluminescence sensors. The membrane-free sensor used in the Black Sea since 1999 and the domestic photoluminescence sensor showed the best results: agreement of data, possibility of fine oxygen distribution resolution, and absence of the oxygen and hydrogen sulfide coexistence layer. The latter has good technical characteristics: high oxygen sensitivity and complete inertness to hydrogen sulfide, possibility of calibration in a gaseous environment, and a relatively low time constant (5–6 s). An equation was suggested for dynamic correction of data in the testing mode, which eliminates hysteresis of data on probe descent and ascent to a significant degree. It was shown that the oxygen concentration above the hydrogen sulfide layer in the subreductive zone of the Black Sea did not exceed 0.02 μM.     

Cooling in the western Bering Sea in 1999: quick propagation of La Niña signal or compensatory processes effect?

In 1999, synoptic and hydrological conditions in the western Bering Sea were characterized by negative SST and air temperature anomalies, extensive ice coverage and late melting. Biological processes were also delayed. In 1999, the average zooplankton biomass was 1.76 g/m³, approximately half the average 3.07 g/m³ in 1998. Pacific salmon migrated to the northeastern Kamchatka streams two weeks later. This contrasts with 1997 (spring and summer) and 1998 (summer) when positive SST anomalies were widely distributed throughout the northwestern Bering Sea shelf. Since the second half of the 1990s, seasonal atmospheric processes developed over the western Bering Sea that were similar to those of the cold decades of the 1960–1970s. A meridional atmospheric circulation pattern began to replace zonal transport. Colder Arctic air masses have shifted over the Bering Sea region and shelf water temperatures have cooled considerably with the weakening of zonal atmospheric circulation. Temperature decreased in the cold intermediate layer during its renewal in winter. Besides, oceanic water inflow intensified into the Bering Sea in intermediate layers. Water temperature warmed to 4°C and a double temperature maximum existed in the warm intermediate layer in late summer in both 1997 and 1998. Opposing trends of cold water temperature and a warm intermediate layer led to an increase of vertical gradients in the main thermocline and progressing frontogenesis. It accelerates frontal transport and can be regarded as a chief cause of increased water exchange with the Pacific Ocean.     

Geology and mineralogy of ore at the hidden Engteri Au-Ag deposit,the Magadan Region

The Engteri is a new hidden Au-Ag deposit in the Russian segment of the Pacific ore belt. The discovery of this deposit merits special attention, because it involves repeated attempts to reappraise a lowprospective ore occurrence, which were crowned with success as a result of fulfillment of large-scale drilling project. The average Au grade is 18.6 gpt. The deposit is classified as the gold geochemical type of Au-Ag deposits. The major ore mineral is pyrite, which amounts to no less than 95% of the total ore minerals. The native phases comprise electrum and to a lesser extent native gold of low fineness (730). The homogenization temperature of fluid inclusions is 125–255°C with a distinct maximum at 145–150°C. Despite blind localization of some orebodies, the Engteri deposits bears evidence for a deep erosion level: (1) small vertical range of economic mineralization (50–100 m); (2) predominant occurrence of massive sugarlike quartz with a low sulfide content; (3) prevalence of massive and brecciated textures above rhythmically banded textures; and (4) lack of low-temperature propylites. The southern part of the ore field distinguished by occurrence of rhythmically banded, framework-tabular, and brecciated texture has the best prospect for revealing new orebodies. The Engteri deposit allowed us to outline the following prospecting guides and methods of prospecting for hidden Au-Ag deposits: (1) these deposits are regularly arranged in ore clusters between heavy concentrate anomalies of cinnabar and gold-silver or silver-base-metal occurrences (method of missed link); (2) findings of fragments of ore mineral assemblages with sporadically high Au and Ag contents in barren calcite-quartz veins (method of indicators); (3) linear zones of ankeritization in the fields of low- and mediumtemperature propylites (mapping of metasomatic rocks); and (4) pyrite-quartz veinlets with rhythmically banded pockets (mineralogical mapping of halos of stringer-disseminated mineralization).     

Seasonal Dynamics of Algal Flora in the Stratified Kislo-Sladkoe Lake Partially Separated from the White Sea

Oceanology - The article presents data on the composition and abundance of algal flora in the coastal stratified Kislo-Sladkoe Lake (the Karelian coast of the White Sea) after its flushing with...     

Spatial variability of the species composition,abundance, and productivity of the phytoplankton in the white sea in the late summer period

The species composition, cell concentration (N), and biomass (B) of the phytoplankton, as well as the chlorophyll a (Chl a) concentration, primary production (PP), and the concentrations of the dissolved inorganic micronutrients (phosphorus, silica, nitrogen as nitrite), were estimated for Kandalaksha Bay (KB), Dvina Bay (DB), and the basin (Bas) of the White Sea in August of 2004. The micronutrient concentrations were lower compared to the average long-term values for the summer period. The Chl a concentration varies from 0.9 to 2.0 mg/m³ for most of the studied areas, reaching up to 7.5 mg/m³ in the Northern Dvina River estuary. The surface water layer of the DB was the most productive area, where the PP reached up to 270–375 mg C/(m³ day). The phytoplankton biomass varied from 11 to 205 mg C/m³ with the highest values observed in the Bas and DB. Three groups of stations were defined during the analysis of the phytoplankton’s species composition similarity. The dinoflagellates Dinophysis norvegica and Ceratium fusus were particular to the phytoplankton assemblages in the KB; the diatom Ditylum brightwellii was particular to the upper and central parts of the DB. These three phytoplankton species were less abundant in the Bas.     

Vertical flux of phytoplankton and particulate matter in the White Sea according to the long-term exposure of sediment traps

The vertical fluxes of phytoplankton (VF_Phyto) and particulate organic carbon (VF_POC) in the White Sea were determined using seven long-term (292 to 296 days) sediment traps moored at five stations at 67–255 m depths. The annual VF_Phyto and VF_POC ranged from 0.55 to 24.64 g C/m² and from 3.7 to 93.9 g C/m², respectively. The highest VFPhyto was observed in the Basin region located close to the Gorlo along the Tersk coast. The algal biomass accounted for 15–43% of the VF_POC. Diatoms comprised the most important group, accounting for 83–100% in the sedimented biomass. Thalassiosira nordenskioeldii dominated in the VF_Phyto at all the stations except for the station in the basin close to Onega Bay, where Ditylum brightwellii was the most abundant.     

Climate change impacts on runoff in the Ferghana Valley (Central Asia)

The main freshwater source of arid/semi-arid Central Asia is stored in its high mountain glaciers. Water for the downstream countries is mainly supplied through the Syrdarya River that originates at the confluence of the Naryn and Karadarya rivers in the Ferghana Valley. Runoff generation from glaciers plays a crucial role, although a considerable number of small tributaries supply the river with additional runoff from snowmelt and rain in the mountains surrounding the Ferghana Valley. Observations of rising air temperature and accelerated glacier shrinkage make it most likely that the relative contributions of the smaller tributaries will increase. Hitherto, assessments of climate change effects on the water resource availability have largely neglected the growing importance of the runoff from smaller tributaries. We used a dynamically downscaled A1B SRES scenario for climate change effects for the period 2071–2100 in relation to the reference period of 1971–2000 and a version of the conceptual hydrological Hydrologiska Byråns Vattenavdelning model (HBV-light) to estimate runoff contributions with particular respect to the small tributaries. The simulations showed a 12–42% decrease in summer runoff; and a 44–107% increase in winter-spring runoff. This indicates the hydrological regime is shifting towards a runoff from snowmelt earlier in the year. The study suggests that actions for climate change adaptation should be complemented by land management configured to secure optimal runoff supplement from the smaller catchments.     

Laboratory and marine study of photoluminescent sensors of oxygen dissolved in seawater

The laboratory and marine study of photoluminescent sensors developed at the TsAGI has been conducted to create a highly sensitivity gauge of the oxygen dissolved in seawater. The advantages of the photoluminescent gauge over the electrochemical ones are the following: zero sensitivity to electromagnetic fields, the pH of the water, and the hydrogen sulphide and ions of heavy metals in the water; zero oxygen consumption; and no need for the water to be pumped through the device.     

Spatial distribution of phytoplankton in the White Sea in the late summer period with regard to the water structure and dynamics

The species composition and biomass of the phytoplankton, as well as the hydrophysical and hydrochemical characteristics of the water masses, were estimated for different areas of the White Sea at 24 stations for the period of August 26 to September 3, 2007. The micronutrient concentrations were lower compared to the average long-term values for the summer period. The total biomass of phytoplankton (B _t ) varied from 87 to 1914 mg C/m². For most of the studied sites, B _t was low; dinoflagellates were the most abundant species. Diatoms dominated in the areas of elevated hydrodynamic activity, i.e., in the Gorlo (vertical mixing of the water layers), in intrusions of the Gorlo water masses into the basin of the White Sea, and in the peripheral areas of the Dvina outflow current. The B _t was also the highest in the listed areas.