Assessment of the long-term safety of radioactive waste disposal: 2. Isotopic study of water exchange in a multilayer system

As a continuation of previous studies of ³H, δ²H, δ¹⁸O, Ar, ⁴⁰Ar/³⁶Ar, and ²³⁴U/²³⁸U isotope systems, data of uranium-helium dating of groundwater at the radioactive waste repository of Siberian Chemical Works are quantitatively interpreted. The interpretation is based on analytical models taking into account the inflow of deep-earth helium and the diffusion-advection exchange between layers. Estimated flow velocities in reservoir beds and buffer horizons are in agreement with previous hydrodynamic estimates. The obtained velocities of horizontal mass transfer were used to evaluate the age of groundwater in sampling points. Water age varies from 7 to 14 (with a mean of ～9) in the lower (II and III) aquifers, into which the radioactive wastes are pumped, from 2 to 4 in buffer horizon IV, and from 1 to 2 thousand years in the upper V horizon.     

Assessment of the long-term safety of radioactive waste disposal: 1. Paleoreconstruction of groundwater formation conditions

Isotopic characteristics (δ²H, δ¹⁸O, ²³⁴U/²³⁸U, Ar, ³H) of natural and technogenically affected waters were determined in the area around the burying grounds of the Siberian Chemical Combine with the aim to assess the circulation conditions of natural waters and the safety of radioactive waste disposal in reservoir beds.     

Plankton as a Factor Modifying the Physical Characteristics in the Marine Environment

Abstract. Some hydrophysical environmental parameters ( e.g . temperature, salinity, transparency, flows, erc .) are known to profoundly affect the structural and functional characteristics and species composition of plankton communities. The purpose of the present work was to assess the opposite - the influence of qualitative and quantitative characteristics of plankton on some optical (light transmission. optical density) and acoustic (sound volume backscattering strength) characteristics in the Black Sea. The influence of specific features (shape, size and color) of planktonic unicells on light attenuation in seawater was examined in laboratory experiments. The data from field studies on variability of statistic characteristics of sound volume backscattering strength in upper productive water layer, depending on species composition and numbers of zooplankton, are given.     

Natural background of hydrocarbon gases (C1–C5) in the waters of the Kara Sea

The distributions of methane and hydrocarbons (HC) C2+ throughout the vertical section of the water mass and sediments of the Kara Sea and the estuaries of the Ob and Yenisei rivers were examine during expeditions aboard the R/V “Akademik Boris Petrov” in 1997–2002. Data obtained during the expeditions and extensive information provided by the complex study of the carbon cycle in the aquatic area were used to analyze the genesis of hydrocarbon gases in marine water. The example of particulate matter was used to demonstrate that hydrocarbon gases of the composition C2–C5 contained in seawater are genetically related to aquatic organic matter (OM), regardless of seawater salinity. The hydrocarbon complex is dominated (80%) by higher C4–C5 homologues. The concentration of C4–C5 hydrocarbons in the estuarine fresh waters is comparable with the high methane concentration (2–3 μl/l), drastically decreases in the zone of water mixing, and then rapidly increases to values several times higher than the methane concentration in seawater outside the outer boundary of the sedimentation depocenter of riverine particulate matter. A direct correlation was established for the concentration of the C4 + C5 homologues with the OM of the water mass, and the leading role was demonstrated to be played by labile OM of the autochthonous biomass (marine phytoplankton) in the genesis of higher hydrocarbon gases (alkenes, alkanes, and isoalkanes) during the early diagenetic stage of OM transformations in water. Along with the biomass of phytoplankton, a significant role in the genesis of C2–C3 hydrocarbons is played by destruction products of terrigenous OM. The destruction of OM and generation of gaseous hydrocarbons, including methane, are restricted to the pycnocline and the water-sediment interface. The absolute predominance of the sum of the C4 + C5 homologues in the hydrocarbon C2+ gases and the presence of unsaturated C2–C4 hydrocarbons are typical of the natural background of hydrocarbons of the Kara Sea water mass.     

Low Frequency Cosmic Background for a Cloudy Interstellar Medium Model

The first interpretation of the cosmic noise background spectrum over a broad frequency band from 0.25 - 200 MHz using a cloudy interstellar medium model is given.     

Transbaikal Mesozoic granites: Mode of crystallization and subsequent metasomatic transformations

Crystallization conditions and early post-magmatic rock alteration have been studied for three orebearing granite massifs using the method of stochastic modeling. These Mesozoic granites were crystallized from a relatively dry melt, whose barren (ore-free) parts were crystallized from a volatile-enriched magma under sealed conditions. Surface zones of weak rock alteration over subsurface mineralization reflect the subsurface structural patterns controlling the mineralization.     

Physicochemical Conditions of the Existence of Early Cambrian Chemotrophic Microbiota in the Zone of Influence of Sulfide Ore-Forming Hydrothermal Solutions

Doklady Earth Sciences - Complex studies of the Early Cambrian Kyzyl-Tashtyg pyrite deposit (East Tuva) allowed us to reconstruct the paleohydrothermal systems, to understand the physicochemical...     

Earthquakes,characteristics of the upper mantle under kamchatka,and their connection with volcanism (according to data collected up to 1971)

This paper presents new data on the upper mantle characteristics, and on seismicity and volcanism in Kamchatka. It is shown that the seismic activity in the Pacific focal layer decreases sharply below that narrow line on which the foci of the active volcanoes are situated. A map of longitudinal wave velocitiesV _p in the mantle upper layers under Kamchatka is given. The lowest values ofV _p (7.3–7.6 km/sec) are found near the volcanic belt. The graphs Θ=lg (E_s/E_p) (h) for the Kamchatka earthquakes indicate that Θ_min at the depths of 120–250 km may be caused by a concentration of magmatic melts. A map of bodies (magma chambers?) screening S- and P-waves at the depths of 30–100 km under Kamchatka has been compiled. These bodies are mainly located under the belt of active volcanoes.     

Volcanic earthquakes of Kamchatka: classification, nature of source and spatio-temporal distribution

Volcanic earthquakes on Kamchatka can be divided into two large groups: earthquakes with depths of 0–40 km generated by stresses which arise during magma migration in the Earth's crust under volcanos (the first group), and the earthquakes directly connected with the eruptions (volcanic tremor, explosive earthquakes, etc.—the second group). This paper presents a review of some energetic, spectral and spatio-temporal characteristics of the Kamchatkan volcanic earthquakes of the first group and their relationship with volcanic phenomena.

Seismicity related to volcanic activity has the following specific features: a local and predominantly swarm-like pattern of earthquake origination; iteration of earthquake swarms in the same seismically active zones; many shallow and relatively small events; a small magnitude limit (up to 5.5–6); the existence of longer-period variations of volcanic earthquake foci as compared to the tectonic one; and a comparatively high value of the slope of the earthquake recurrence plot. At the same time, similarity in behaviour of some parameters of the seismic regime during the preparation and development of eruptions and prior to large earthquakes, as well as the destruction of samples, are noted.     

How rough sea affects marine seismic data and deghosting procedures

Most seismic processing algorithms generally consider the sea surface as a flat reflector. However, acquisition of marine seismic data often takes place in weather conditions where this approximation is inaccurate. The distortion in the seismic wavelet introduced by the rough sea may influence (for example) deghosting results, as deghosting operators are typically recursive and sensitive to the changes in the seismic signal. In this paper, we study the effect of sea surface roughness on conventional (5–160 Hz) and ultra‐high‐resolution (200–3500 Hz) single‐component towed‐streamer data. To this end, we numerically simulate reflections from a rough sea surface using the Kirchhoff approximation. Our modelling demonstrates that for conventional seismic frequency band sea roughness can distort results of standard one‐dimensional and two‐dimensional deterministic deghosting. To mitigate this effect, we introduce regularisation and optimisation based on the minimum‐energy criterion and show that this improves the processing output significantly. Analysis of ultra‐high‐resolution field data in conjunction with modelling shows that even relatively calm sea state (i.e., 15 cm wave height) introduces significant changes in the seismic signal for ultra‐high‐frequency band. These changes in amplitude and arrival time may degrade the results of deghosting. Using the field dataset, we show how the minimum‐energy optimisation of deghosting parameters improves the processing result.