High-amplitude lake-level changes in tectonically active Lake Issyk-Kul (Kyrgyzstan) revealed by high-resolution seismic reflection data

A total of 84 seismic profiles, mainly from the western and eastern deltas of Lake Issyk-Kul, were used to identify lake-level changes. Seven stratigraphic sequences were reconstructed, each containing a series of delta lobes that were formed during former lake-level stillstands or during slow lake-level increase or decrease. The lake level has experienced at least four cycles of stepwise rise and fall of 400 m or more. These fluctuations were mainly caused by past changes in the atmospheric circulation pattern. During periods of low lake levels, the Siberian High was likely to be strong, bringing dry air masses from the Mongolian steppe blocking the midlatitude Westerlies. During periods of high lake levels, the Siberian High must have been weaker or displaced, and the midlatitude Westerlies could bring moister air masses from the Mediterranean and North Atlantic regions

Morphology and recent history of the Rhone River Delta in Lake Geneva (Switzerland)

The current topographic maps of the Rhone Delta—and of Lake Geneva in general—are mainly based on hydrographic data that were acquired during the time of F.-A. Forel at the end of the nineteenth century. In this paper we present results of a new bathymetric survey, based on single- and multi-beam echosounder data. The new data, presented as a digital terrain model, show a well-structured lake bottom morphology, reflecting depositional and erosional processes that shape the lake floor. As a major geomorphologic element, the sub-aquatic Rhone Delta extends from the coastal platform to the depositional fans of the central plain of the lake at 310m depth. 9 canyons cut the platform edge of the delta. These are sinuous ("meandering”) channels formed by erosional and depositional processes, as indicated by the steep erosional canyon walls and the depositional levees on the canyon shoulders. Ripples or dune-like morphologies wrinkle the canyon bottoms and some slope areas. Subaquatic mass movements are apparently missing on the delta and are of minor importance on the lateral lake slopes. Morphologies of the underlying bedrock and small local river deltas are located along the lateral slopes of Lake Geneva. Based on historical maps, the recent history of the Rhone River connection to the sub-aquatic delta and the canyons is reconstructed. The transition from three to two river branches dates to 1830-1840, when the river branch to the Le Bouveret lake bay was cut. The transition from two to one river branch corresponds to the achievement of the correction and dam construction work on the modern Rhone River channel between 1870 and 188

Возраст грязевой брекчии грязев ых вулканов Академического хреб та озера Байка

Lake Baikal is the only freshwater reservoir on Earth with gas-hydrate accumulations in its bottom sediments, partly due to the activity of mud volcanoes. This paper describes a group of mud volcanoes recently discovered on the slope of the Academician Ridge between the northern and central Lake Baikal basins. Our analysis of diatom skeletons in the mud breccia sampled from the study area shows a high abundance of Cyclotella iris et var. These extinct species were also discovered in a core sample from BDP-98 borehole. Based on the biostratigraphic and seis-mostratigraphic correlations, the age of the mud breccia in the studied mud volcanoes ranges from the Late Miocene to the Early Pliocene (4.6 to 5.6 Ma). The correlations suggest that the material originated from a depth of less than 310 m below the lake bottom

Atmospheric methane flux from bubbling seeps: Spatially extrapolated quantification from a Black Sea shelf area

Bubble transport of methane from shallow seep sites in the Black Sea west of the Crimea Peninsula between 70 and 112 m water depth has been studied by extrapolation of results gained through different hydroacoustic methods and direct sampling. Ship-based hydroacoustic echo sounders can locate bubble releasing seep sites very precisely and facilitate their correlation with geological or other features at the seafloor. Here, the backscatter strength of a multibeam system was integrated with single-beam data to estimate the amount of seeps/m2 for different backscatter intensities, resulting in 2709 vents in total. Direct flux measurements by submersible revealed methane fluxes from individual vents of 0.32–0.85 l/min or 14.5–37.8 mmol/min at ambient pressure and temperature conditions. A conservative estimate of 30 mmol/min per site was used to estimate the flux into the water to be 1219–1355 mmol/s. The flux to the atmosphere was calculated by applying a bubble dissolution model taking release depth, temperature, gas composition, and bubble size spectra into account. The flux into the atmosphere (3930–4533 mol/d) or into the mixed layer (6186–6899 mol/d) from the 21.8 km2 large study area is three times higher than independently measured fluxes of dissolved methane for the same area using geochemical methods (1030–2495 mol/d). The amount of methane dissolving in the mixed layer is 2256–2366 mol/d. This close match shows that the hydroacoustic approach for extrapolating the number of seeps/m2 and the applied bubble dissolution model are suitable to extrapolate methane fluxes over larger areas

Constraining the Oceanic Uptake and Fluxes of Greenhouse Gases by Building an Ocean Network of Certified Stations: The Ocean Component of the Integrated Carbon Observation System, ICOS-Oceans

The European Research Infrastructure Consortium “Integrated Carbon Observation System” (ICOS) aims at delivering high quality greenhouse gas (GHG) observations and derived data products (e.g., regional GHG-flux maps) for constraining the GHG balance on a European level, on a sustained long-term basis. The marine domain (ICOS-Oceans) currently consists of 11 Ship of Opportunity lines (SOOP – Ship of Opportunity Program) and 10 Fixed Ocean Stations (FOSs) spread across European waters, including the North Atlantic and Arctic Oceans and the Barents, North, Baltic, and Mediterranean Seas. The stations operate in a harmonized and standardized way based on community-proven protocols and methods for ocean GHG observations, improving operational conformity as well as quality control and assurance of the data. This enables the network to focus on long term research into the marine carbon cycle and the anthropogenic carbon sink, while preparing the network to include other GHG fluxes. ICOS data are processed on a near real-time basis and will be published on the ICOS Carbon Portal (CP), allowing monthly estimates of CO2 air-sea exchange to be quantified for European waters. ICOS establishes transparent operational data management routines following the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles allowing amongst others reproducibility, interoperability, and traceability. The ICOS-Oceans network is actively integrating with the atmospheric (e.g., improved atmospheric measurements onboard SOOP lines) and ecosystem (e.g., oceanic direct gas flux measurements) domains of ICOS, and utilizes techniques developed by the ICOS Central Facilities and the CP. There is a strong interaction with the international ocean carbon cycle community to enhance interoperability and harmonize data flow. The future vision of ICOS-Oceans includes ship-based ocean survey sections to obtain a three-dimensional understanding of marine carbon cycle processes and optimize the existing network design

Geo- and hydro-acoustic manifestations of shallow gas and gas seeps in the Dnepr paleodelta, northwestern Black Sea

Shallow gas occurs between 0 and 1000 m below the sea floor. It consists mainly of microbial-formed or thermogenic methane or a combination of both, sometimes with a limited admixture of higher hydrocarbons (propane, butane, etc.)

Identification of novel cyclin-dependent kinases interacting with the CKS1 protein of Arabidopsis

The SUC1/CKS1 proteins interact with cyclin-dependent kinases (CDKs) and play an essential, but yet not entirely resolved, role in the regulation of the cell cycle. With the Arabidopsis thaliana CKS1At: protein as bait in a two-hybrid screen. two novel Arabidopsis CDKs, Arath;CDKB1;2 and Arath;CDKB2;1, were isolated. A closely related homologue of Arath;CDKB2;1 was discovered in the databases and was nominated Arath;CDKB2;2. Transcript analysis of the five known Arath;CDKA and Arath;CDKB genes revealed that they all had the highest expression in flowers and cell suspensions. Differences in the expression patterns in roots, leaves and stems suggest unique roles for each CDK

Stratigraphic and structural control on the distribution of gas hydrates and active gas seeps on the Posolsky Bank, Lake Baikal

The distribution and origin of shallow gas seeps in the vicinity of the Posolsky Bank in Lake Baikal were studied based on the integration of detailed seismic, multibeam, and hydro-acoustic water-column investigations. In all, 65 acoustic flares have been detected on the Posolsky Fault scarp near the crest of the bank and in a similar, nearby setting at water depths of -43 to -332 m. The seismic data reveal BSRs (bottom-simulating reflectors) occurring up to water depths of -300 m. Calculations involving hydrate stability, heat flow, and topographic modulation based on BSR occurrence and multibeam bathymetry enabled prediction of a methane-ethane gas mixture and heat-flow values that would account for gas hydrate stability in the lake sediments under prevailing ambient conditions. These predictions are supported by ground truth data. The findings suggest that seeps concentrated along the crest of the Posolsky Bank are fed mainly by gas coming from below the base of the gas hydrate stability zone, which would migrate updip via permeable stratigraphic pathways beneath the bank. Gas would ultimately be released into the water column where these pathways are cut off by faults