István Fórizs

Transit time determination for a riverbank filtration system using oxygen isotope data and the lumped-parameter model

Abstract The mathematical description of the lumped-parameter Dispersion Model is presented, and its use for estimating transit time and proportion of river water in a riverbank filtration system on Szentendre Island (in the Danube River, Hungary) is assessed by applying stable oxygen isotope data. The modelling approach could only be used to analyse single oxygen-isotope peaks observed during a 6-month-long time series, because the mean input (Danube) concentration was very close to the output (well) concentration. The water level in the Danube varied, but the lumped-parameter approach is only applicable for steady-state conditions. Isotope data observed during quasi steady-state hydraulic conditions selected at medium and higher water levels were modelled. At low water levels the method could not be used because the 18O content of the Danube water and of collector wells was similar. Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus Citation Kármán, K., Maloszewski, P., Deák, J., Fórizs, I. and Szabó, C., 2014. Transit time determination for a riverbank filtration system using oxygen isotope data and the lumped-parameter model. Hydrological Sciences Journal, 59 (6), 1109–1116. http://dx.doi.org/10.1080/02626667.2013.808345

Linking silicate weathering to riverine geochemistry—A case study from a mountainous tropical setting in west-central Panama

Chemical analyses from 71 watersheds across an ∼450 km transect in west-central Panama provide insight into controls on weathering and rates of chemical denudation and CO2 consumption across an igneous arc terrain in the tropics. Stream and river compositions across this region of Panama are generally dilute, having a total dissolved solute value = 118 ± 91 mg/L, with bicarbonate and silica being the predominant dissolved species. Solute, stable isotope, and radiogenic isotope compositions are consistent with dissolution of igneous rocks present in Panama by meteoric precipitation, with geochemical signatures of rivers largely acquired in their upstream regions. Comparison of a headwater basin with its entire watershed observed considerably more runoff production from the high-elevation upstream portion of the catchment than in its much more spatially extensive downstream region. Rock alteration profiles document that weathering proceeds primarily by dissolution of feldspar and pyroxene, with base cations effectively leached in the following sequence: Na > Ca > Mg > K. Control on water chemistry by bedrock lithology is indicated through a linking of elevated ([Na + K]/[Ca + Mg]) ratios in waters to a high proportion of catchment area silicic bedrock and low ratios to mafic bedrock. Sr-isotope ratios are dominated by basement-derived Sr, with only very minor, if any, contribution from other sources. Cation weathering of Casil + Mgsil + Na + K spans about an order in magnitude, from 3 to 32 tons/km2/yr. Strong positive correlations of chemical denudation and CO2 consumption are observed with precipitation, mean watershed elevation, extent of land surface forest cover, and physical erosion rate.

Origin of Thermal Waters in Budapest Based on Chemical and Isotope Investigations Including Chlorine-36

Budapest is a major spa center with numerous thermal baths that are open to the public. Thermal spas in Budapest were first developed by the Romans and followed by the Turks, present spas were built mainly in the 19th and 20th centuries. At the city of Budapest the Danube River flows along a geological fault which separates the Buda Hills from the Great Plain. Within this fault zone in the vicinity of the Danube more than 100 thermal springs are arising yielding totally about 40,000 m3 per day of warm mineral water. In this study the results of thermal, chemical and isotope analyses (including tritium and chlorine-36) of 12 thermal springs and wells are presented. These results are interpreted with respect to the origin and recharge conditions of the investigated thermal waters.

Stable isotope signatures of seasonal precipitation on the Pacific coast of central Panama

As calculated from data archived in the IAEA-WMO Global Network of Isotopes in Precipitation programme, the amount-weighted local meteoric water line for the Pacific coast of central Panama is: δ2H = 7.63(±0.08) × δ18O + 6.51(±0.49). Amount-weighted mean isotopic values were regressed against the sea surface temperature (SST) fields of the adjacent tropical oceans. A negative correlation of precipitation isotope composition with Caribbean SSTs is observed only for the early wet season (May–June), whilst the mid-summer dry period is characterized by positive correlation with eastern Pacific SSTs, similar to the late wet season (October–November). The negative response of May–June rainfall isotopic composition to Caribbean SSTs is explained by a SST-mediated change in stratiform rain fraction from organized convective systems proximal to the Inter Tropical Convergence Zone (ITCZ). The positive correlation for the rest of the wet season, when the organized convective zone of ITCZ and its attached stratiform belt are distant from the Pacific coast of Panama, is interpreted as simple evaporative temperature effect on isotopic fractionation.

Introductory Editorial: Thematic issue: “Utilization of Thermal and Mineral Waters”

This special thematic issue contains selected presentations from the 2012 yearly meeting of the International Association of Hydrogeologists (IAH) Commission on Mineral and Thermal Waters (CMTW). The meeting and longestablished framework of a field trip in conjunction with it was held 12–18 August 2015, in Budapest and several other Hungarian locales. Main topics of the meeting were Groundwater, Thermal and Mineral water in karstic terrains and porous sedimentary basins, and Utilization of thermal and mineral waters. The Headquarters of the Hungarian Academy of Sciences in Budapest was the location for a day-long series of nine presentations covering three main topics:

A 14,000-year diatom oxygen isotope record from the Romanian South Carpathians reflect changes in the seasonal distribution of precipitation and temperature

Oxygen isotope records from lacustrine sediments have the potential to reflect short-term and long-term changes in temperature, seasonal changes in the distribution of precipitation and changes in lake water budget determined by the evaporation to inflow ratio. This proxy has widely been used in the Alps and NW Europe to provide high-resolution temperature or evaporation records, but similar studies in the Carpathians are missing. Here we provide a continuous Lateglacial and Holocene record of diatom silica oxygen isotope changes (δ 18 O DIAT ) in a subalpine lake sediment sequence coming from the northern flank of the Retezat Mts (Taul dintre Brazi, TDB, 1740 m a.s.l.).

A preliminary stable isotope study on a potential radioactive waste repository site in the Mecsek Mountains, Southern Hungary

A potential repository site for high-activity radioactive waste is investigated in the vicinity of a former uranium mine in the Mecsek Mts. (S. Hungary). In order to evaluate the usefulness of the site, stable H, C and O isotope compositions of shallow groundwaters, repository site waters, carbonate veins and fluid inclusions of the veins have been measured. Shallow groundwaters have H and O isotope compositions identical to those of the present day local precipitation water, whereas repository site waters show δD and δ18O values characteristic of Pleistocene meteoric waters. Based on δ13C, δ18O and δD (inclusion fluid) data, the calcite veins might have been formed by movements of meteoric water originating from precipitation in a warmer climate of the geological past. The results indicate that no significant infiltration of surface waters to the investigated repository site occurs, but signs of migration of Pleistocene waters along the veins has been observed.