Prospects for exploration of hydrogen fields in riftogene structures of platforms (the case of the Dnieper-Donets Aulacogene)

This paper shows the prospect to find industrial-scale hydrogen accumulations in riftogenic structures of platforms using the example of the Dnieper-Donets Aulacogene, located in the southern part of the East European Platform. Within the Dnieper-Donets Depression, geological and geophysical methods indicate a significant number of deep faults and ring structures of volcanogenic and explosive origin promising increased hydrogen content. Possible locations of the most propitious areas of hydrogen concentration are associated with faults in rift systems and their nearest margins, as well as with explosive and volcanogenic ring structures with signs of modern activation. At a fine-grained level, the prospectivity of the area is determined not only by the specified structural relationship, but also by the set of geophysical characteristics (thermal, seismic, gravity, electrical conductivity, magnetic) and the corresponding geological and hydrogeological parameters. Areas for further more detailed investigations within the Sribne and other ring structures, Southern Near-Edge Fault, Northern Near-Edge Fault were identified based on the data on geological and geophysical materials, satellite images, and field work. We defined high-priority and low-priority territories. Areas for initial investigations using satellite images, gas sampling (hydrogen, helium, methane, etc.), primary geophysical surveys (with evaluation of intermediate reservoirs and cap rocks) were identified. The primary results can be used to plan pilot shallow drilling and wells sampling. The areas for priority deeper drilling and sampling are selected by the sum of results obtained and data comparison. The paper presents the results obtained 30 km east of Kyiv as an example of field assessment of H2 degassing in a local depression. The results show that hydrogen concentrations at depths of 0.45 to 1.5 m are near zero outside the local depression. The maximum values of H2 concentration (up to 3300 ppm 1.5 m deep) are characteristic of the point inside the depression.

Supercooling of Seawater Near the Glacier Front in a Fjord

We analyze seawater temperature and salinity in the immediate vicinity of the Paulbreen front in Spitsbergen. The CTD-measurements were carried out from ice in winter and from a boat in summer. ADCP profiling was performed near the glacier front from the ice in winter. In winter, we found water with lower salinity than the surrounding water in the fjord at a distance of 15 m from the glacier front and recorded a low upward water flux near the glacier. Relatively fresh water was found at a depth of 2-4 m near the glacier front in the place where the sea and glacier bed have local depression up to 17 m. Supercooling of the freshened water reached 0.35°C. We link this phenomenon to a flow of freshwater from under a polythermal glacier. This water becomes overcooled in the seawater with significantly lower temperature and higher salinity.

On Geological and Geophysical Safety of the New Safe Confinement for ChNPP-4

The paper considers evidences and mechanisms of potential impact of local depression (microgeodynamic) zones on NPP safety. The depression forms were revealed within the Chornobyl NPP site, including location of the new safe confinement. Nature of zones and character of their influence is determined by fault structures and conjugated deep degassing processes, which cannot be detected and studied by traditional methods of engineering and exploration works during NPP siting. The assumption was made that significant and still unexplored risks for nuclear facilities are related to probable release of deep hydrogen through the bottom of depressions along sub-bottom channels. The approaches were proposed to studying the system of “depression with its sub-bottom channel” within the sites of Chornobyl NPP and other nuclear power plants.

Pre-Camber Study on the Steel-Concrete Composite Beam Constructed by the Incremental Launching Method

This paper summarized and evaluated the girder construction methods of self-anchored suspension bridge, pointed out that the main beam linear would have a local depression between the largest span temporary pier when the steel-concrete composite beams were constructed by the incremental launching construction method, even if the main beam were withstand uniform bar-forces, moreover, the pre-camber curve of the main-girder could not arranged as a circle curve or quadratic parabola within the entire span. In view of this, the entire construction process of a self-anchored suspension bridge was analyzed by the finite element method, The results showed that the section property changes of the steel-concrete composite beam were the nature reason of the local depression on the main beam linear; The completed main beam was simplified into a three-span continuous beam which suffered vertical uniform distributing load and horizontal forces at the two ends, and the simplified formulas of calculating the vertical displacement of each span were derived by the force method; The numerical example showed that, the proposed simplified formulas could effectively solve the affection by the section property changes, accurately predicted the main beam cumulative vertical displacement, and the calculation accuracy could meet the engineering requirements, the conclusions of this paper had a strong guiding significance and reference value on the camber design and construction of the bridge wth the similar structural type.

The parasitic ascomycete Mniaecia jungermanniae induces the formation of giant perichaetia and apogamous sporophytes in leafy liverworts

To test the hypothesis that the apothecia of Mniaecia jungermanniae (Nees ex Fr.) Boud. growing on stems of the liverwort Cephalozia bicuspidata (L.) Dumort. might be the perfect stage of an ascomycete fungus forming a symbiotic association with swollen rhizoids in a liverwort, we grew both axenically and resynthesized the association. Contrary to our expectation, Mniaecia remained extracellular, but induced, on Cephalozia , the formation of giant perichaetia containing supernumerary archegonia followed by parthenogenetic and apogamous sporophytes. This is the first report of these latter two features in liverworts. By analogy with apogamy and apospory in mosses and pteridophytes that are induced by media supplemented with organic nutrients and growth regulators, we suggest that the abnormal structures in Cephalozia resulted from substances produced by Mniaecia. Giant perichaetia and abnormal perianths were also observed on wild colonies of Cephalozia, Diplophyllum , and Scapania heavily infected with Mniaecia. Apart from local depression of perianth formation in the wild, this parasitic fungus appears to cause no long-term damage to its hosts.

Groundwater control to the rescue: two case histories

Two case histories are discussed where groundwater lowering was used to permit completion of excavations that experienced problems because of the lack of groundwater control.The first case involved a 4.1 m diameter tunnel, some 26 m below grade, within a clay stratum sandwiched between two water-bearing, granular deposits. Several collapses of the tunnel roof occurred because of a local depression in the surface of the clay stratum, allowing the upper, water-charged granular material to flow into the tunnel. Subsequent investigations indicated the feasibility of lowering the groundwater level by means of an eductor well system, allowing completion of the tunnel in relatively dry conditions.The second case describes groundwater problems associated with the sinking of a 21 m deep exploratory mine shaft through water-bearing silts and sands. Three attempts at sinking the shaft without groundwater control had failed. Therefore, based on the results of a pumping test, eductor wells were installed around a steel sheet pile cofferdam to permit the successful sinking of the shaft to bedrock.