Combining multiple isotope and noble gas data with seismic profiles in an interpretation of hydro-geochemical anomalies

Environmental isotopes (δ18O, δD, δ13C, 14C, 87Sr/86Sr), combined with hydrogeochemical data and seismic profile interpretation, have been used in studying regional groundwater flow systems in the Pannonian Basin. An interpretation of seismic profiles indicates the existence of faults systems, some of them being traceable from the Pre-Cenozoic basement up to near-surface Quaternary sediments. The Lakitelek study area shows high He contents (22 to 25 %) of mantle origin, where fault lines might have been reactivated during recent geological times and facilitated the occurrence of mantle-derived He in the groundwater. The Mezőtúr study area, where most H- and O-isotope compositions are shifted from the global meteoric water line, exhibits 7.6 to 10.6 % He of mantle origin,. The deepest sample indicates mixing with formation waters. Here basement faults might not have been reactivated, since they do not seem to have an active role on the groundwater composition and effects of the regional flow system seem to be the dominant factor determining the groundwater isotope compositions

Anthropogenic impacts on mineral weathering: A statistical perspective

Correspondence Analysis was adopted as tool for investigating the statistical structure of hydrochemical and weathering datasets of groundwater samples, with the main purpose of identifying impacts on mineral weathering caused by anthropogenic activities, namely fertilizing of farmlands. The hydrochemical dataset comprised measured concentrations of major inorganic compounds dissolved in groundwater, namely bicarbonate, silica (usually by-products of chemical weathering), chloride, sulphate and nitrate (typically atmospheric plus anthropogenic inputs). The weathering dataset consisted of calculated mass transfers of minerals being dissolved in loess sediments of a region located in SW Hungary (Szigetvár area), namely Na-plagioclase, calcite and dolomite, and of pollution-related concentrations of sodium, magnesium and calcium. A first run of Correspondence Analysis described groundwater composition in the study area as a system of triple influence, where spots of domestic effluents-dominated chemistries are surrounded by areas with agriculture-dominated chemistries, both imprinted over large regions of weathering dominated chemistries. A second run revealed that nitrification of N-fertilizers is promoting mineral weathering by the nitric acid reaction (anthropogenic pathway), in concurrence with the retreating of weathering by carbonic acid (natural pathway). It also indicated that dolomite and calcite are being players in a dedolomitization process driven by dissolution of gypsum fertilizers and nitrification of N-fertilizers. © 2013 Elsevier Ltd

Hydrogeochemistry in Transboundary Thermal Water Management

AbstractThis study gives a brief and general overview of the hydrogeology and hydrogeochemistry of the transboundary geothermal resources in the western part of the Pannonian Basin, carried out within the framework of a joint Hungarian, Slovenian, Slovakian and Austrian project (TRANSENERGY). Chemical and isotope data were used to describe the different flow systems, to calculate the groundwater ages along both the flow paths and the main discharge zones, and to help calibrate the hydrogeological flow and transport models used as input for a sustainable transboundary thermal water management scheme

Bridging hydraulic diffusivity from aquifer to particle-size scale: a study on loess sediments from southwest Hungary

In situ megascale hydraulic diffusivities (D) of a confined loess aquifer were estimated at various scales (10 <= L <= 1500 m) by a finite difference model, and laboratory microscale diffusivities of a loess sample by empirical formulas. A scatter plot reveals that D fits to a single power function of L, providing that microscale diffusivities are assigned to L = 1 m and that differences in diffusivity observed between micro- and megascales are assigned to medium heterogeneity appraised by variations in the curvature and slope of natural hydraulic head waves propagating through the aquifer. Subsequently, a general power relationship between D and L is defined where the base and exponent terms stand for the aquifer storage capability under a confined regime of flow, for the microscale hydraulic conductivity and specific yield of loess, and for the changes in curvature and slope of hydraulic head waves relative to values defined at unit scale.[GRAPHICS]Editor Z.W. Kundzewic

Transboundary geothermal resources of the Mura-Zala basin: a need for joint thermal aquifer management of Slovenia and Hungary

Large transboundary Upper Miocene geothermal sandy aquifers which are widely utilized by both countries forbalneological and direct heat purposes exist in the Slovenian-Hungarian border region. In NE Slovenia the totaldirect heat use was 382 TJ in 2010, while in SW Hungary it was 648 TJ, including utilization from basement reservoirs.The total installed capacity of the 13 Slovenian users was 38.8 MWt, while that of the 29 Hungarian userswas 70.6 MWt. Utilisation takes place without harmonized management strategies which might endanger the longtermsustainability of these systems. We aimed to overcome this by delineating a transboundary thermal groundwaterbody (TTGWB) Mura-Zala with an aerial extent of 4,974 km2 and with vertical extent between depths 500–2,200 m, which was done based on detailed geological, hydrological, geochemical and geothermal models as wellas numerical modelling. The regional groundwater flow in the Mura-Zala TTGWB is from west to east in general,the modeled cross-border flow is approximately 50 l/s. At present, thermal water abstraction rates from the Mura/Újfalu Fm. (61.8 l/s in the Slovenian and 67.3 l/s in the Hungarian part of the TTGWB) does not endanger the goodregional quantity status of the water body, and this should be maintained by allowing a maximum increase of thermalwater abstraction 3.5 times higher than today. However, to achieve target numbers for an increased proportionof geothermal energy in the total energy mix in both countries, we suggest that increase of thermal efficiency andre-injection should be prioritized apart from the higher thermal water abstraction with setting up limit of themaximum allowable drawdown