In the Szigetvár area, SW Hungary, shallow groundwaters draining upper Pleistocene loess and Holocene sediments are considerably contaminated by domestic effluents and leachates of farmland fertilizers. The loess contains calcite and dolomite, but gypsum was not recognized in these sediments. The anthropogenic inputs contain significant amounts of calcium and sulfate. The calcium from these anthropogenic inputs is promoting calcite growth, with concomitant consumption of carbonate alkalinity, undersaturation of the system with respect to dolomite, and dolomite dissolution; in brief, is driving "dedolomitization reactions". Geochemical arguments supporting the occurrence of "dedolomitization reactions" in the area are provided by the results of mass balance and thermodynamic analyses. The mass balances predicted the weather sequence dolomite > calcite > plagioclase > K-feldspar, at odds with widely accepted sequences of weatherability where calcite is the first mineral in the row. The exchange between calcite and dolomite can be a side effect of "dedolomitization reactions" because they cause precipitation of calcite. The thermodynamic prerequisites for "dedolomitization reactions" are satisfied by most local groundwaters (70%) since they are supersaturated (or in equilibrium) with respect to calcite, undersaturated (or in equilibrium) with respect to dolomite, and undersaturated with respect to gypsum. The calcium vs. sulfate and magnesium vs. sulfate trends are also compatible with homologous trends resulting from "dedolomitization reactions".

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Large transboundary Upper Miocene geothermal sandy aquifers which are widely utilized by both countries for balneological and direct heat purposes exist in the Slovenian-Hungarian border region. In NE Slovenia the total direct 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 MW t , while that of the 29 Hungarian users was 70.6 MW t . Utilisation takes place without harmonized management strategies which might endanger the longterm sustainability of these systems. We aimed to overcome this by delineating a transboundary thermal groundwater body (TTGWB) Mura-Zala with an aerial extent of 4,974 km 2 and with vertical extent between depths 500-2,200 m, which was done based on detailed geological, hydrological, geochemical and geothermal models as well as 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 good regional quantity status of the water body, and this should be maintained by allowing a maximum increase of thermal water abstraction 3.5 times higher than today. However, to achieve target numbers for an increased proportion of geothermal energy in the total energy mix in both countries, we suggest that increase of thermal efficiency and re-injection should be prioritized apart from the higher thermal water abstraction with setting up limit of the maximum allowable drawdown. Izvle~ekNa mejnem obmo~ju med Slovenijo in Madžarsko so razprostranjeni obsežni, prekomejni zgornjemiocenski geotermalni pe{~eni vodonosniki, ki se v obeh državah uporabljajo predvsem v balneolo{ke namene in za direktno rabo toplote. V severovzhodni Sloveniji je skupna direktna raba toplote v letu 2010 dosegla 382 TJ, v jugovzhodnem delu Madžarske pa 648 TJ, vklju~no z rabo vodonosnikov v podlagi neogenskih kamnin. Celotna in{talirana kapaciteta 13 slovenskih uporabnikov je zna{ala 38,8 MW t , medtem ko je in{talirana kapaciteta pri 29 madžarskih uporabnikih dosegla 70,6 MW t . Uporaba poteka brez usklajene strategije upravljanja, kar lahko ogrozi dolgoro~no vzdržnost teh sistemov. To smo želeli prese~i z opredelitvijo prekomejnega Mursko-Zalskega telesa termalne podzemne vode (VTPodV Mura-Zala) s povr{ino 4.974 km 2 in vertikalnim razponom globine 500-2200 m, dolo~enega na podlagi podrobnih geolo{kih, hidrogeolo{kih, geokemi~nih in geotermalnih modelov, kot tudi numeri~nega modela podzemne vode. Tok podzemne vode v VTPodV Mura-Zala je usmerjen pretežno v smeri zahod-vzhod, pri ~emer je prekomejni tok ocenjen na približno 50 l/s. Pri trenutni koli~ini odvzema termalne vode (~ 61,8 l/s iz slovenskega ter ~ 67,3 l/s iz madžarskega dela VTPodV Mura-Zala) koli~insko stanje telesa ni ogroženo, a njegovo dobro stanje je potrebno ohranjati ...

Quaternary fluvial succession of the Jászság Basin (Hungary) was investigated, challenging the stratigraphical potential of ‘early postglacial fluvial magnetic susceptibility episodes' recognized earlier in the Körös Basin. Low field magnetic susceptibility (MS) was measured in four boreholes from the basin centre and margins, representing channel and flood‐plain environments. Statistical distributions of MS data contain significant sets of outliers, regardless of facies conditions. The downhole distribution of these outliers produces magnetic susceptibility cycles. Supported by magnetic susceptibility cycles, high‐resolution facies correlations were performed reflecting a steady palaeohydrographical situation in the area, with a trunk river to the southeast and tributaries to the northwest. SEM‐EDX data revealed that ferromagnetic grains are responsible for the outlying MS values. The heterogeneous association of magnetite indicates a catchment area with volcanic and metamorphic rocks, while the group of small (<5 μm) magnetite octahedrons originated from nearby rhyolitic tuff formations. Magnetic grains were transported along channel belts, while small (<2 μm) magnetic particles were floated onto flood‐plains attached to clays. Climatic control is indicated by peaks at ~100 ka frequency in spectra of MS records and was also detected in palaeosol development and in flood frequency using the spectra of measured colour (~100 ka) and logged resistivity (~100 ka, ~41 ka), respectively. The climate‐dependent MS signal traceable far into the basin in both channel and flood‐plain environments can be summoned when the Quaternary fluvial succession of the Pannonian Basin is investigated, assuming some sources of magnetite in the catchment areas. According to the concept of ‘fluvial magnetic susceptibility episodes’, the early postglacial escape and spreading of the magnetite fraction control the MS signal that can support mapping of the unconformable Quaternary base and building of high‐resolution models of aquifers.

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susceptibility as a proxy for long-term variations of mountain permafrost development in the Alp-Carpathian region.