Structural solutions and hydrometric parameters of fish passage and spawning channel tracts with elements of enhanced roughness

Purpose: to develop proposals for the design and methodology for calculating the hydrometric parameters of fish passage and spawning channel tracts at waterworks. Materials and methods. The factual basis of the work is data of hydrometric studies of the Nikolaevsky and Konstantinovsky fish passage and spawning channels and materials of technical justification of channel projects at the Bagaevsky and Kochetovsky waterworks on the river Don. The methodological basis of study was the results of the authors’ research and well-known recommendations for determining the parameters of channel tracts with enhanced roughness. Results. The hydrometric parameters of fish passage and spawning channels are accepted and calculated assuming the provision of necessary conditions for attracting anadromous fish into the channels, their passage from the downstream of the waterworks to the upstreams and the spawning of some of them in the tracts. The following parameters were considered: flow rate, average flow velocity, bottom depth and width, cross-sectional shape and slope ratio, underwater gradient and channel length, types and sizes of gravel-pebble channel coating and elements of enhanced roughness. As a result of the study, the recommendations for flow rates, flow velocities and depths, the choice of the cross-section of the channel, the type and size of fractions of the gravel-pebble mixture were proposed. A methodology for hydraulic calculation of the fish passage and spawning channel tracts has been developed for the accepted conditions of its operation taking into account the arrangement of the channel with enhanced roughness elements. To test the methodology, the hydrometric parameters of the conditional fish passage and spawning channel tract, equipped with enhanced roughness elements, with an average flow velocity of 0.9 m/s was calculated. Conclusion. Recommendations for calculating the hydrometric parameters of fish passage and spawning channel tracts with enhanced roughness elements and a methodology for such calculations that meet the requirements of fish farming and biological justification on formation of conditions for fish migration and spawning in their tracts are proposed

Trace Element Patterns in Shells of Mussels (Bivalvia) Allow to Distinguish between Fresh- and Brackish-Water Coastal Environments of the Subarctic and Boreal Zone

The accumulation of trace metals in the shells of bivalves allows quantitative assessments of environmental pollution and helps to reconstruct paleo aquatic environments. However, the understanding on how marine and freshwater mollusks control the level of trace elements in their shells remains very limited. Here, we compared the trace element composition of marine and freshwater bivalves from boreal and subarctic habitats, using examples of widely distributed species of marine (Mytilus edulis, M. trossulus) and freshwater (Anodonta anatina, Unio sp., Beringiana beringiana) mussels. Sizable differences in several trace element concentrations were detected between different species, depending on their environmental niches. A multiparametric statistical treatment of the shell’s elemental composition allowed to distinguish the impact of external factors (water and sediment chemical composition) from active metabolic (biological) control. In particular, the obtained results demonstrated that Ba:Ca and Pb:Ca ratios in mussels’ shells are closely related to the primary productivity of aquatic ecosystems. The Mn:Ca ratio allowed to constrain the environmental conditions of mussels’ species depending on the trophic state of inhabited waterbody. Overall, the marine mussels exhibited stronger biological control of trace element accumulation, whereas trace element pattern in shells of freshwater mussels was chiefly controlled by environmental factors. The obtained results might help to use the trace element composition of bivalves in distinguishing marine and freshwater habitats of mollusks in paleo environments

Constructive and Destructive Processes During the 2018–2019 Eruption Episode at Shiveluch Volcano, Kamchatka, Studied From Satellite and Aerial Data

Dome-building volcanoes often develop by intrusion and extrusion, recurrent destabilization and sector collapses, and renewed volcanic growth inside the collapse embayment. However, details of the structural architecture affiliated with renewed volcanic activity and the influences of regional structures remain poorly understood. Here, we analyze the recent activity of Shiveluch volcano, Kamchatka Peninsula, characterized by repeated episodes of lava dome growth and destruction due to large explosions and gravity-driven collapses. We collect and process a multisensor dataset comprising high-resolution optical (aerial and tri-stereo Pleiades satellite), radar (TerraSAR-X and TanDEM-X satellites), and thermal (aerial and MODIS, Sentinel-2, and Landsat 8 satellites) data. We investigate the evolution of the 2018–2019 eruption episode and evaluate the morphological and structural changes that led to the August 29, 2019 explosive eruption and partial dome collapse. Our results show that a new massive lava lobe gradually extruded onto the SW flank of the dome, concurrent with magmatic intrusion into the eastern dome sector, adding 0.15 km3 to the lava dome complex. As the amphitheater infilled, new eruption craters emerged along a SW-NE alignment close to the amphitheater rim. Then, the large August 29, 2019 explosive eruption occurred, followed by partial dome collapse, which was initially directed away from this SW-NE trend. The eruption and collapse removed 0.11 km3 of the dome edifice and led to the formation of a new central SW-NE-elongated crater with dimensions of 430 m × 490 m, a collapse scar at the eastern part of the dome, and pyroclastic density currents that traveled ∼12 km downslope. This work sheds light on the structural architecture dominated by a SW-NE lineament and the complex interplay of volcano constructive and destructive processes. We develop a conceptual model emphasizing the relevance of structural trends, namely, 1) a SW-NE-oriented (possibly regional) structure and 2) the infilled amphitheater and its decollement surface, both of which are vital for understanding the directions of growth and collapse and for assessing the potential hazards at both Shiveluch and dome-building volcanoes elsewhere

Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015

Zooplankton abundance and vertical fluxes of sedimentary matter and chemical elements in the White Sea from 15 to 24 June, 2000

A multidisciplinary oceanographic survey of the White Sea was carried out in the Gorlo Straight, Basin, and Kandalaksha Bay regions including estuaries of Niva, Kolvitza and Knyazhaya rivers. Hydrophysical study in the northern part of the Basin revealed long-lived step-like structures and inversions in vertical profiles of temperature and salinity, which formed due to tidal mixing of saline and cold Barents Sea waters and warmer White Sea waters in the Gorlo Straight. Biological studies revealed the main features of spatial distribution, as well as qualitative and quantitative composition of phyto- and zooplankton in all studied areas; tolerance of main zooplankton species to fresh water influence in estuaries was shown. Study of suspended matter in estuaries clearly demonstrated physicochemical transformations of material supplied by the rivers. Data on vertical particle flux in the deep part of the Kandalaksha Bay showed difference between the upper and near-bottom layers, which could result from sinking of spring phytoplankton bloom products and supply of terrigenic suspended matter from the nepheloid layer formed by tidal currents