Influence of water level fluctuation on the spatial dynamic of the water chemistry at Lake Fertõ/Neusiedler See

Lake Fertõ/Neusiedler See is a steppe lake situated on the Hungarian-Austrian border with a surface area of 309 km². It is an extremely shallow lake with regulated outflow. 54% of the whole lake and 85% of the Hungarian part (75 km²) is covered by reed. There are numerous reedless areas (inner ponds) of variable size within the reed belt, which is enmeshed with canals connecting the inner ponds with the open water areas. Fundamental differences were recorded in the water chemistry of the three water type areas, open water, canals and inner ponds. The degree of these differences is basically determined by the distance from the open water areas and the water level of the actual years. An extremely high, an average and an extremely low water level year was examined, in order to present the spatial and temporal differences in the water chemistry of the investigated water bodies. Differences due to the water level fluctuation between years in the three different water types are discussed on the basis of electrical conductivity, cation, and anion concentration changes of the water. Our results support the concept of high instability of Lake Fertõ and describe habitats with remarkable temporal and spatial variability. The high influence of water level on habitat conditions at different sites of the lake recommend a carefull water level regulation strategy.     

Accessing effects and signals of leakage from a CO<Subscript>2</Subscript> reservoir to a shallow freshwater aquifer by reactive transport modelling

CO₂ geological storage is a transitional technology for the mitigation of climate change. In the vicinity of potential CO₂ reservoirs in Hungary, protected freshwater aquifers used for drinking water supplies exist. Effects of disaster events of CO₂ escape and brine displacement to one of these aquifers have been studied by kinetic 1D reactive transport modelling in PHREEQC. Besides verifying that ion concentrations in the freshwater may increase up to drinking water limit values in both scenarios (CO₂ or brine leakage), total porosity of the rock is estimated. Pore volume is expected to increase at the entry point of CO₂ and to decrease at further distances, whereas it shows minor increase along the flow path for the effect of brine inflow. Additionally, electrical conductivity of water is estimated and suggested to be the best parameter to measure for cost-effective monitoring of both worst-case leakage scenarios.     

充分发挥岩土力学数值分析与解析方法的效能——第三届全国岩土力学数值分析与解析方法讨论会论文选登

岩土力学是力学学科的一个重要分支,也是一门应用性很强的工程学科。岩土介质作为一种地质材料,因不同的形成历史与条件,除物质组成不同外,还具有不同的微观、细观和宏观结构,这就使岩土介质与其他固体材料有着重大的差别。     

Life in the sublittoral zone of long-lived Lake Pannon: paleontological analysis of the Upper Miocene Szák Formation,Hungary

Life and depositional environments in the sublittoral zone of Lake Pannon, a large, brackish Paratethyan lake from the Late Miocene, were reconstructed from fossils and facies of the Szák Formation. This formation is exposed in several, roughly coeval (9.4–8.9 Ma) outcrops, located along strike of the paleo-shelf-break in northwestern Hungary. The silty argillaceous marl of the formation was deposited below storm wave base, at 20–30 to 80–90 m water depth. The abundance of benthic organisms indicates that the bottom water was usually well oxygenated. Interstitial dysoxia, however, may have occurred immediately below the sediment–water interface, as evidenced by occasional preservation of trace fossils such as Diplocraterion. The fauna comprised endemic mollusks, including brackish cockles of the subfamily Lymnocardiinae, dreissenid mussels (Congeria), and highly adapted, uniquely large-sized deep-water pulmonate snails (planorbids and lymnaeids). Ostracods were dominated by endemic species and, in some cases, endemic genera of candonids, leptocytherids, cypridids, and loxoconchids. Fish remnants include a sciaenid otolith and the oldest skeletal occurrence of Perca in Europe. The phytoplankton comprised exclusively endemic coccolithophorids, mostly endemic dinoflagellates (prevailingly Spiniferites), and cosmopolitan green algae. The Late Miocene fauna and flora of Lake Pannon were in many ways similar to the modern Caspian biota, and in particular cases can be regarded as its precursor.     

Magnetic susceptibility as a possible correlation tool in Quaternary alluvial stratigraphy

Correlation of the fluvial magnetic susceptibility (MS) record of borehole Devavanya‐1 in the Körös Basin (eastern Hungary) with Chinese aeolian MS records (Jingbian, Lingtai) and the marine δ¹⁸O record from the Equatorial Pacific (V28‐239) is established here based on cross‐correlations and singular spectral analysis. A basin‐scale well‐to‐well correlation based on magnetic susceptibility records was also performed involving unpublished cores. To refine the age model, a Monte Carlo simulation was conducted using the Chinese Jingbian section as a tuning target. Spectral analysis of the tuned record revealed c. 400, c. 100 and c. 41 ka cycles over the 2.5 million years of the Quaternary fluvial succession. To ensure a complementary palaeoclimate proxy, the full width at half maximum of smectites was measured as a facies‐independent indicator of weathering intensity. This investigation was carried out on a subset of samples involved in MS measurements representing a c. 400 ka time interval across the top of the Olduvai subchron. A phase‐shift between MS and weathering intensity recorded in the clay mineralogy indicates different response times of the considered proxies. The fluvial MS record is determined by the climatic control on delivery and preservation of magnetic minerals, mainly of magnetite. Under cold‐and‐dry climate these minerals were released owing to frost shattering in the adjacent hinterlands and were transported to alluvial plains in the early postglacial periods thanks to the increasing discharge of rivers. With further warming the weathering‐sensitive magnetic minerals soon disappeared from the soils of the catchment area and thus from the fluvial load. As a result, in fluvial successions early postglacial warmings are expressed by the occurrences of MS maxima (magnetic episodes), while the palaeotemperature maximum and the subsequent cooling remain concealed within the tract of low MS values. The early postglacial magnetic episodes may serve as ideal stratigraphical markers in regional and global correlations.     

OSL-dating the Quaternary landscape evolution in the Vértes Hills forelands (Hungary)

Fluvial, colluvial, and aeolian sediments were dated by optically stimulated luminescence (OSL) on quartz to improve the chronological framework for Quaternary sedimentation and landscape evolution in the forelands of the Vértes Hills (central Hungary). The separated quartz was suitable for age determination based on an OSL SAR protocol. Most samples have asymmetric equivalent dose distributions and OSL ages were calculated by the mean, central, and minimum D_e values. Considering geomorphology and earlier age data from the area, the central D_e values seem most appropriate for age calculation. A fan on the geomorphological level QV in the western foreland of the Vértes Hills was deposited 79–75 (±8) ka ago. In the south-eastern foreland an alluvial fan on level QIIb is at most 42 ± 4 ka old. Fluvial incision and aggradation occurred 16–10 (±1) ka ago on the geomorphic surface QIIa. Loess is 14 ± 1 ka old, and slope sedimentation was active 11–9 (±1) ka ago. Our OSL data demonstrate that in the north-western foreland of the Vértes Hills wind remained an important agent after the last glacial times, into the early Holocene (9–8 ± 1 ka) and was able to accumulate large aeolian dunes.     

Provenance of the Upper Triassic siliciclastics of the Mecsek Mountains and Villány Hills (Pannonian Basin,Hungary): constraints to the Early Mesozoic paleogeography of the Tisza Megaunit

International Journal of Earth Sciences - The Tisza Megaunit in the Southern Pannonian Basin formed part of the southern margin of the European Plate in the Early Mesozoic era. Its exact...     

Distribution of relict permafrost features in the Pannonian Basin,Hungary

Wedge structures and involutions suggest that Late Pleistocene frozen ground, either permafrost or deep seasonal frost, extended at least as far south as latitude 47°N in central Europe (the Pannonian Basin). Optically stimulated luminescence dating of the sand infill from a number of wedges indicates that emplacement of the sand infill occurred during the Late Pleistocene (22.2–15.7 ka). This suggests that during this time the mean annual air temperature was depressed by at least ～15°C relative to the present. Either continuous or discontinuous permafrost was probably present in the north and NW of the Pannonian Basin. The subsequent thaw of frozen ground is indicated by the widespread occurrence of deformed sediments. The presence of soil (ground) wedges suggests conditions of deep seasonal frost probably existed during the period when climate ameliorated following the Last Permafrost Maximum (LPM).     

Luminescence dating of historical fluvial deposits from the Danube and Ebro

The validity of optically stimulated luminescence (OSL) has been tested on known‐age (historical) fluvial deposits along the rivers Danube (Austria) and Ebro (Spain). As partial bleaching of the OSL signal prior to deposition can interfere with correct age estimates, different approaches to extracting the dose accumulated during burial are compared. Using the finite mixture model gave OSL ages that are internally as well as stratigraphically consistent and in agreement with independent age control. According to these results, fluvial deposition at the Danube River study site can be attributed to different periods ranging from Bronze Age to the 18th century A.D. Fluvial deposits of Roman age and of the late 17th or early 18th century A.D. were found at the Ebro River study site. This is consistent with the morphological subdivision of the valleys and encourages further investigation of the fluvial and archaeological history of the study areas using OSL. © 2009 Wiley Periodicals, Inc.