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 Aquatic GeochemistryJournal Prestige (SJR): 0.591 Citation Impact (citeScore): 1Number of Followers: 4      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1573-1421 - ISSN (Online) 1380-6165 Published by Springer-Verlag  [2351 journals]
• Tufa Deposition Dynamics in a Freshwater Karstic Stream Influenced by Warm
Springs
• Abstract: Sweet Springs Creek, located in the Valley and Ridge Province of the Appalachian Mountains in southeastern West Virginia and southwestern Virginia, USA, contains major fluvial tufa formations at the sites of localized fractures and faults. Sweet Springs Creek receives input from higher-temperature thermal springs of lower pH and higher sulfate concentration that differ significantly in chemical composition due to differences in the underlying geology. In this study, theoretical rates of tufa accumulation were compared with those measured on travertine tiles left in situ for 30 days during periods of high and low stream flow above and below the sites of major fluvial tufa formations. Consistent with the chemistry of the spring waters, observed and predicted tufa accumulation rates in the stream were low compared to others reported worldwide. Tufa formation rate estimates were consistently higher during seasonal conditions of low flow, warm temperatures, and higher pH that occurred in late summer, but net annual accumulation may still be zero or less due to formation erosion during periodic flooding events. Computer tomography analysis determined that the natural porosity of travertine tiles results in a total surface area 32% greater than that calculated based solely on tile dimensions, which may overestimate initial tufa accumulation rates in situ. Measured rates of carbonate deposition on travertine tiles were 1.6–82 × lower than rates predicted based on theoretical models, consistent with the hypothesis of rate reduction due to variable diffusional boundary layer limitations and variability in stream hydrology. The generation of loose, platy, and unconsolidated precipitate on tiles under geochemical conditions predicted to be the greatest for optimal tufa formation suggested that the precipitation of particulate calcite in the stream system may predominantly result in the formation of unconsolidated marl deposits.
PubDate: 2019-08-19

• Multicomponent Versus Classical Geothermometry: Applicability of Both
Geothermometers in a Medium-Enthalpy Geothermal System in India
• Abstract: The Manuguru geothermal area, located in the Khammam district of Telangana state, India, is one of the least explored medium-enthalpy geothermal systems in India. In this study, subsurface reservoir temperature was estimated by applying various methodologies such as chemical geothermometry, multicomponent geothermometry and mixing models. Chemical geothermometers provided wide range in temperature estimation, and most of them (Na–K, Na–K–Ca, Mg-corrected Na–K–Ca) were found to be unsuitable for predicting reservoir temperature due to the absence of attainment of equilibrium between suitable mineral pairs. The temperature range estimated from the quartz geothermometers varied from 72 to 120 °C which matched closely with values obtained from K–Mg geothermometers. To overcome this problem and to better constrain the reservoir temperature, multicomponent solute geothermometry modelling was carried out by applying the GeoT computer code. Fluid reconstruction was done after taking into account both the degassing and mixing phenomena. GeoT modelling of the reconstructed fluid provided excellent clustering of the minerals. From the GeoT modelling study, it was found that minerals like quartz, chalcedony, calcite, etc., attained simultaneous equilibrium with thermal waters in the temperature range of 130 ± 10 °C, which can be taken as the most probable reservoir temperature. The subsurface temperature (137 °C) obtained from the mixing model further validated the results obtained from multicomponent geothermometry. This integrated multicomponent method and the simulation program used in this study take into account various processes (i.e. mixing, degassing, non-attainment of equilibrium, etc.) which affect the composition of the thermal fluids during its ascent to the surface. The statistical approach of ‘best clustering minerals’ used in this model helps to overcome the problems encountered in applying cation or single-component geothermometers in the medium-enthalpy geothermal systems.
PubDate: 2019-08-09

• Editorial
• PubDate: 2019-06-29

• Isotopic Composition and Origin of Sulfide and Sulfate Species of Sulfur
in Thermal Waters of Jiangxi Province (China)
• Abstract: The reduced sulfur species, sulfide, elemental and thiosulfate were considered in the thermal waters of Jiangxi Province for the first time. It is shown that the sulfur speciation content significantly varies and depends on the pH values. The major part of reduced sulfur refers to sulfide species in the nitric thermal waters, to elemental—in the carbon dioxide thermal waters. The presence of both reduced and oxidized sulfur speciation indicates the possibility of sulfide minerals hydrolysis and disproportionation of the product of this reaction (SO2) with the participation of hot water with the formation of elemental and sulfate sulfur. The isotopic composition of dissolved sulfate and sulfide sulfur speciation has shown that the process of bacterial reduction proceeds in the thermal waters, accompanied by accumulation of relatively heavy sulfur isotope in sulfates. Simultaneously with reduction, the oxidation of both sulfide minerals and newly formed hydrosulfide proceeds with formation of elemental, thiosulfates and also sulfates in the discharge zone was proceeded. It is shown that the process of sulfide oxidation mostly occurs in carbon dioxide thermal waters. Therefore, the elemental sulfur is predominant in carbon dioxide waters. The oxidation process is less significant in the nitric thermal waters, whereby the concentrations of sulfide ion are higher than sulfates. The ambiguous effect of sulfate reduction on the hydrogeochemical environment of the thermal waters is confirmed by the differing value of the carbon isotope ratio of HCO3− in the considered waters. The obtained isotopic composition data 34δS(SO42−) indicate host rocks as a source of sulfates in the thermal waters of Jiangxi Province.
PubDate: 2019-06-13

• An Integrated Isotope-Geochemical Approach to Characterize a Medium
Enthalpy Geothermal System in India
• Abstract: The Manuguru geothermal area, situated in the Telangana state, is one of the least explored geothermal fields in India. In this study, the chemical characteristics of the groundwater (thermal and non-thermal waters) are investigated to elucidate the source of the solutes dissolved in the water and to determine the approximate residence time of the thermal waters. The major hydrogeochemical processes controlling the groundwater geochemistry have been deciphered using multivariate statistical analysis, conventional graphical plots and geochemical modelling (PHREEQC). Geochemically different groundwater clusters (bicarbonate type, bicarbonate–chloride type and chloride type) can clearly be identified from the chemometric analysis, i.e. PCA and HCA. Thermal waters are mostly Na–HCO3 type having low EC and TDS compared to non-thermal groundwaters. Silicate weathering and ion exchange mainly contribute to the dissolved ion budget in the groundwater of the study area. The carbon isotopic composition of DIC (δ13C) points to silicate weathering with soil CO2 coming from C3 type of plants. Stable isotopes (δ18O, δ2H) data confirm the meteoric origin of the thermal waters with no oxygen-18 shift. The low tritium values of the thermal water samples reveal the long circulation time (> 50 years) of the recharging waters. Radiocarbon dating (14C) shows that the approximate residence time of the thermal waters ranges from 9952 to 18,663 year BP (before present).
PubDate: 2019-04-26

• Geochemistry of Chilean Rivers Within the Central Zone: Distinguishing the
Impact of Mining, Lithology and Physical Weathering
• Abstract: Several rivers of Chile from the latitude 30°–38° have been sampled during a stable anticyclonic period (October 2008). Firstly, our aim was to evaluate the dissolved chemical composition (major and trace elements) of poorly known central Chilean rivers. Secondly, we used a co-inertia analysis (see Dolédec and Chessel in Freshw Biol 31:277–294, 1994) to explore the possible relationships between the concentrations of elements and the environmental parameters [surface of the basin (km2)/mining activity (%)/average height (m)/watershed mean slope (%)/% of the surface covered by vegetation, sedimentary rocks, volcano-sedimentary rocks, volcanic rocks, granitoid rocks/erosion rate (mm/year)]. Globally, the major elements concentration could be explained by a strong control of mixed silicate and carbonate and evaporate lithology. The statistical treatment reveals that the highest metal and metalloids loads of Tinguiririca, Cachapoal, Aconcagua, Choapa, Illapel and Limari could be explained by the contribution of the mining activities in the uppermost part of these watersheds and/or by the higher geochemical background. Indeed, it remains difficult to decipher between a real mining impact and a higher geochemical background. Even if these rivers could be impacted by AMD process, the size of these watersheds is capable of diluting AMD waters by the alkaline character of tributaries that induce acid neutralization and decrease the level of metals and metalloids.
PubDate: 2019-03-20

• The Speciation and Mobility of Mn and Fe in Estuarine Sediments
• Abstract: Dissolved and solid-phase speciation of Mn and Fe was measured in the porewaters of sediments recovered from three sites in the Greater St. Lawrence Estuary: the Saguenay Fjord, the Lower St. Lawrence Estuary (LSLE) and the Gulf of St. Lawrence (GSL). At all sites and most depths, metal organic ligand complexes (Mn(III)–L and Fe(III)–L) dominated the sedimentary porewater speciation, making up to 100% of the total dissolved Mn or Fe. We propose that these complexes play a previously underestimated role in maintaining oxidized soluble metal species in sedimentary systems and in stabilizing organic matter in the form of soluble metal–organic complexes. In the fjord porewaters, strong (log KCOND > 13.2) and weak (log KCOND < 13.2) Mn(III)–L complexes were detected, whereas only weak Mn(III)–L complexes were detected at the pelagic and hemipelagic sites of the GSL and LSLE, respectively. At the fjord site, Mn(III)–L complexes were kinetically stabilized against reduction by Fe(II), even when Fe(II) concentrations were as high as 57 μM. Only dissolved Mn(II) was released from the sediments to overlying waters, suggesting that Mn(III) may be preferentially oxidized by sedimentary microbes at or near the sediment–water interface. We calculated the dissolved Mn(II) fluxes from the sediments to the overlying waters to be 0.24 µmol cm−2 year−1 at the pelagic site (GSL), 11 µmol cm−2 year−1 at the hemipelagic site (LSLE) and 2.0 µmol cm−2 year−1 in the fjord. The higher benthic flux in the LSLE reflects the lower oxygen concentrations (dO2) of the bottom waters and sediments at this site, which favor the reductive dissolution of Mn oxides as well as the decrease in the oxidation rate of dissolved Mn(II) diffusing through the oxic layer of the sediment and its release to the overlying water.
PubDate: 2019-03-15

• Evaluation of Hydrogeochemical Processes for Waters’ Chemical
Composition and Stable Isotope Investigation of Groundwater/Surface Water
in Karst-Dominated Terrain, the Upper Tigris River Basin, Turkey
• Authors: E. Dişli
Abstract: The Upper Tigris River Basin is one of the biggest basins in Turkey, where municipal, agricultural and industrial water supplies are highly dependent on groundwater and surface water resources. The interpretation of plots for different major ions indicates that the chemical compositions of the surface/groundwater in the Upper Tigris River Basin are dominated Ca2+, Mg2+, HCO3− and SO42− which have been arisen largely from chemical weathering of carbonate and evaporate rock, and reverse ion exchange reactions. Isotopic composition of surface and groundwater samples is influenced by two main air mass trajectories: one originating from the Central Anatolia that is cold and rainy and another originating from the rains falling over northeastern Syria that is warm and rainy, with warm winds. The relative abundance of cations and anions in water samples is in the order: Ca2+  > Mg2+  > Na+  > K+ for cations and HCO 3 −   > Cl− > SO42−, respectively. Majority of the water samples are plotted on a Piper diagram showing that the chemical composition of the water samples was predominantly Ca–Mg–HCO3 type. Groundwater and surface water have an average (Ca2+ + Mg2+/2HCO3−) ratio of 0.65 and 0.74, indicating no significant difference in their relative solute distribution and dissolution of carbonate rock (calcite and dolomite) predominantly by carbonic acid. The Mg2+/Ca2+ and Mg2+/ HCO3− molar ratio values are ranging from 0.21 to 1.30 and 0.11 to 0.47 for the groundwater and from 0.13 to 2.46 and 0.10 to 0.61 for the surface water samples, respectively, indicating that significant contribution of dolomite dissolution has a higher advantage over limestone within the Upper Tigris River Basin.
PubDate: 2019-02-26
DOI: 10.1007/s10498-019-09349-8

• Acknowledgement to Reviewers 2018
• PubDate: 2019-02-15
DOI: 10.1007/s10498-019-09348-9

• Detection of Biochar Carbon by Fluorescence and Near-Infrared-Based
Chemometrics
• Authors: Minori Uchimiya; Alan J. Franzluebbers; Zhongzhen Liu; Marshall C. Lamb; Ronald. B. Sorensen
Abstract: Large-scale biochar field trials have been conducted worldwide to test for “carbon negative strategy” in the event of carbon credit and if other subsidies become enacted in the future. Once amended to the soil, biochar engages in complex organo-mineral interactions, fragmentation, transport, and other aging mechanisms exhibiting interactions with treatments including the irrigation and fertilizer application. As a result, quantitative tracing of biochar carbon relying on the routinely measured soil parameters, e.g., total/particulate organic carbon, poses a significant analytical uncertainty. This study utilized two biochar field trial sites to calibrate for the biochar carbon structure and quantity based on the infrared- and fluorescence-based chemometrics: (1) slow pyrolysis biochar pellets on kaolinitic Greenville fine sandy loam in Georgia and (2) fast pyrolysis biochar powder on Crider silt loam in Kentucky. Partial least squares-based calibration was constructed to predict the amount of solvent (toluene/methanol)-extractable fluorescence fingerprint (290/350 nm excitation and emission peak) attributed to biochar based on the comparison with the authentic standard. Near-infrared-based detection was sensitive to the C–H and C–C bands, as a function of biochar loading and the particulate organic carbon content (< 53 μm) of the bulk soil. Developed chemometrics could be used to validate tarry carbon structures intrinsic to biochar additives, as the impact of biochar additives on soil chemical properties (pH, electric conductivity, and dissolved organic carbon) becomes attenuated over time.
PubDate: 2019-02-14
DOI: 10.1007/s10498-018-9347-9

• Reduction of Manganese Oxides: Thermodynamic, Kinetic and Mechanistic
Considerations for One- Versus Two-Electron Transfer Steps
• Authors: George W. Luther; Aubin Thibault de Chanvalon; Véronique E. Oldham; Emily R. Estes; Bradley M. Tebo; Andrew S. Madison
Pages: 257 - 277
Abstract: Manganese oxides, typically similar to δ-MnO2, form in the aquatic environment at near neutral pH via bacterially promoted oxidation of Mn(II) species by O2, as the reaction of [Mn(H2O)6]2+ with O2 alone is not thermodynamically favorable below pH of ~ 9. As manganese oxide species are reduced by the triphenylmethane compound leucoberbelein blue (LBB) to form the colored oxidized form of LBB (λmax = 623 nm), their concentration in the aquatic environment can be determined in aqueous environmental samples (e.g., across the oxic–anoxic interface of the Chesapeake Bay, the hemipelagic St. Lawrence Estuary and the Broadkill River estuary surrounded by salt marsh wetlands), and their reaction progress can be followed in kinetic studies. The LBB reaction with oxidized Mn solids can occur via a hydrogen atom transfer (HAT) reaction, which is a one-electron transfer process, but is unfavorable with oxidized Fe solids. HAT thermodynamics are also favorable for nitrite with LBB and MnO2 with ammonia (NH3). Reactions are unfavorable for NH4+ and sulfide with oxidized Fe and Mn solids, and NH3 with oxidized Fe solids. In laboratory studies and aquatic environments, the reduction of manganese oxides leads to the formation of Mn(III)-ligand complexes [Mn(III)L] at significant concentrations even when two-electron reductants react with MnO2. Key reductants are hydrogen sulfide, Fe(II) and organic ligands, including the siderophore desferioxamine-B. We present laboratory data on the reaction of colloidal MnO2 solutions (λmax ~ 370 nm) with these reductants. In marine waters, colloidal forms of Mn oxides (< 0.2 µm) have not been detected as Mn oxides are quantitatively trapped on 0.2-µm filters. Thus, the reactivity of Mn oxides with reductants depends on surface reactions and possible surface defects. In the case of MnO2, Mn(IV) is an inert cation in octahedral coordination; thus, an inner-sphere process is likely for electrons to go into the empty e g * conduction band of its orbitals. Using frontier molecular orbital theory and band theory, we discuss aspects of these surface reactions and possible surface defects that may promote MnO2 reduction using laboratory and field data for the reaction of MnO2 with hydrogen sulfide and other reductants.
PubDate: 2018-08-01
DOI: 10.1007/s10498-018-9342-1
Issue No: Vol. 24, No. 4 (2018)

• Uranium and Multi-element Release from Orthogneiss and Granite (Austria):
Experimental Approach Versus Groundwater Composition
• Authors: Daniel Elster; Edith Haslinger; Martin Dietzel; Heinz Fröschl; Gerhard Schubert
Pages: 279 - 306
Abstract: In this study, the release of elements and in particular U from five Austrian orthogneiss and granite samples into a CO2-bearing solution was investigated to describe the initial phase (24 h) of leaching focusing on the impact of ferrous (hydro)oxide formation. Experiments were conducted at ambient temperature by flushing CO2:N2 gas through the reactive solution (pHinitial ~ 4.3) at a liquid:solid ratio of 10:1 with and without a reducing agent. The chemical evolution of the leaching solution was dominated by incongruent dissolution of silicates showing a parabolic kinetic behavior due to protective surface formation most likely caused by precipitation of amorphous FeIII/Al hydroxides. However, the relative distribution of Ca, Mg and Sr in the leaching solution excellently traced the individual bulk rock composition. The mobilization of U was highly prevented under oxidizing conditions by sorption onto ferrous (hydro)oxides, which were precipitating through ongoing silicate leaching. Therefore, the leaching behavior of individual U-bearing minerals was less relevant for U release. At reducing conditions, the above elements were accumulated in the solution, although an oversaturation regarding UIVO2 was calculated. This indicates its inhibited formation within the experimental run time. The composition of experimental leaching solutions did not reflect analyzed groundwater compositions from investigated local rock-type aquifers indicating that reaction rate constants of siliceous rocks significantly differ between values found in nature and in the laboratory. Change in active mineral surface areas with ongoing weathering, accumulation of secondary precipitates, leached layer formation and given reaction time are key factors for distinct elemental release.
PubDate: 2018-08-01
DOI: 10.1007/s10498-018-9344-z
Issue No: Vol. 24, No. 4 (2018)

• Potential Influence of Ocean Acidification on Deep-Sea Fe–Mn Nodules and
Pelagic Clays: An Improved Assessment by Using Artificial Seawater
• Authors: Quan Wang; Hodaka Kawahata; Kyoko Yamaoka; Atsushi Suzuki
Pages: 307 - 322
Abstract: In order to assess the potential risk of metal release from deep-sea sediments in response to pH decrease in seawater, the mobility of elements from ferromanganese (Fe–Mn) nodules and pelagic clays was examined. Two geochemical reference samples (JMn-1 and JMS-2) were reacted with the pH-controlled artificial seawater (ASW) using a CO2-induced pH regulation system. Our experiments demonstrated that deep-sea sediments have weak buffer capacities by acid–base dissociation of surface hydroxyl groups on metal oxides/oxyhydroxides and silicate minerals. Element concentrations in the ASW were mainly controlled by elemental speciation in the solid phase and sorption–desorption reaction between the charged solid surface and ion species in the ASW. These results indicated that the release of heavy metals such as Mn, Cu, Zn and Cd should be taken into consideration when assessing the influence of ocean acidification on deep-sea environment.
PubDate: 2018-08-01
DOI: 10.1007/s10498-018-9345-y
Issue No: Vol. 24, No. 4 (2018)

• Correction to: A Tribute to Rick and Debbie Jahnke: From Deep Sea Pore
Water to Coastal Permeable Sediments-Contributions that Cover the Oceans
• Authors: Timothy J. Shaw; Steve Emerson; Herbert L. Windom
Pages: 323 - 323
Abstract: In the original publication of the article, the third author affiliation was incorrectly published.
PubDate: 2018-08-01
DOI: 10.1007/s10498-018-9343-0
Issue No: Vol. 24, No. 4 (2018)

• Oxygen Consumption in Permeable and Cohesive Sediments of the Gulf of
Aqaba
• Authors: Valeria Boyko; Adi Torfstein; Alexey Kamyshny
Pages: 165 - 193
Abstract: Oxygen profiles were measured in the sediments of the Gulf of Aqaba (Red Sea), an oligotrophic marine system affected by episodic seasonal flash floods and intense aeolian dry deposition. Sediment cores were retrieved from shallow (15–45 m), intermediate (250–561 m) and deep (700 m) water sites of south–north and east–west transects. Dissolved oxygen concentrations were measured simultaneously by using microelectrodes and microoptodes immediately after sampling and after transportation. Oxygen penetration depths were found to increase from 2 to 5 mm at the shallow water sites with sandy permeable sediments to 10–21 mm at the deeper sites with cohesive muddy sediments. This increase corresponds to decrease in oxygen diffusive fluxes at the sediment–water interface and oxygen consumption rates with depth. Oxygen consumption rates exhibit local maxima at the oxic–anoxic sediment boundary, which may be attributed to oxygen reduction coupled to oxidation of dissolved Fe(II) and Mn(II) at deep and intermediate water sites and of hydrogen sulfide at shallow water sites. Microelectrodes and microoptodes measurements of cohesive sediments from deep and intermediate water sites yielded similar results. By comparison, the microoptodes displayed more robust measurements than microelectrodes in sandy near-shore sediments. This was attributed to their flexible fiber structure that is less likely to break or to abruptly displace sand particles. After transportation of sediment cores from Eilat to Beer Sheva followed by ≤ 24-h storage, no changes in oxygen fluxes and consumption rates were detected.
PubDate: 2018-06-01
DOI: 10.1007/s10498-018-9338-x
Issue No: Vol. 24, No. 3 (2018)

• Fluorescence Quenching and Energy Transfer Phenomena Associated with the
Interactions of Terbium Ion and Humic Acid
• Authors: Mingquan Yan; Gregory V. Korshin; Marc F. Benedetti; Chi-Wang Li
Pages: 195 - 207
Abstract: Fluorescence of the hydrophobic acid fraction (HPOA) of Suwannee River natural organic matter and Tb3+ excitation spectra were measured in tandem using the instantaneous and time-resolved emission modes. The intensity of HPOA fluorescence decreased in the presence of Tb3+, while the intensity of the emission from Tb3+ cations bound by HPOA increased by up to several orders of magnitude due to energy transfer (ET) from HPOA to Tb3+ ions. To determine intrinsic ET and fluorescence quenching (FQ) coefficients, NICA–Donnan modeling was carried. It showed that phenolic groups in HPOA dominated both the ET and FQ processes and that the binding of Tb3+ by HPOA could be described using the non-ideality parameter nTb, median binding constant log $$\tilde{K}_{\text{Tb}}$$ for the phenolic sites and intrinsic ET and FQ coefficients (denoted as ηTbΦ and αTbΦ), and were 0.48, 8.5, 1385 and 0.12, respectively. The high value of the energy transfer coefficient of Tb3+ ions bound by the phenolic groups in HPOA is indicative of both the match between the electronic levels of the donor and acceptor, and the short distance between them. The deviation of the data of Nica–Donnan modeling of the ET and FQ dependence of versus [Tb]total for a 1.0 M ionic strength highlights the need to quantify the distribution of donor–acceptor distances in HPOA molecules in more detail.
PubDate: 2018-06-01
DOI: 10.1007/s10498-018-9339-9
Issue No: Vol. 24, No. 3 (2018)

• Salt Crystallization Sequences of Nonmarine Brine and Their Application
for the Formation of Potassium Deposits
• Authors: Chuanyong Ye; Jianye Mao; Yaqiong Ren; Yingping Li; Yongjie Lin; Ian M. Power; Yangbing Luo
Pages: 209 - 229
Abstract: The salt assemblages precipitated during evaporation of concentrated brine collected from Gasikule Salt Lake (GSL) were studied to better understand the formation of potassium deposits in the Qaidam Basin. The study included isothermal evaporation at 25 °C in the laboratory and solar evaporation in the ponds at GSL field. Brines increased in density and became moderately acidic (pH ≈ 5.30) while major ion geochemistry and precipitate mineralogy all showed broad agreement between both systems. Four salt assemblages were identified in the isothermal evaporation experiment: halite → halite + hexahydrite → halite + bischofite + carnallite → bischofite. Alternately, three salt assemblages were recognized in the solar evaporation: halite → halite + epsomite + carnallite → halite + carnallite + bischofite. The key difference in salt assemblages between the two systems is attributed to differences in relative humidity and temperature conditions. Although the GSL has deep spring inflow recharge, the high abundance of MgSO4 salts demonstrates that the salt assemblages are similar to normal seawater evaporation. Thus, different proportions of deep spring inflow and river water could form both MgSO4-deficient potassium evaporite and normal seawater potassium evaporites. Therefore, nonmarine water may form diverse potassium evaporite deposits in continental basins when the geological structure as well as hydrogeological and climatic conditions is appropriate.
PubDate: 2018-06-01
DOI: 10.1007/s10498-018-9340-3
Issue No: Vol. 24, No. 3 (2018)

• Integration of In Situ Experiments and Numerical Simulations to Reveal the
Physicochemical Circumstances of Organic and Inorganic Precipitation at a
Thermal Spring
• Authors: Petra Kovács-Bodor; Dóra Anda; Laura Jurecska; Mihály Óvári; Ákos Horváth; Judit Makk; Vincent Post; Imre Müller; Judit Mádl-Szőnyi
Pages: 231 - 255
Abstract: Organic and inorganic precipitates are both characteristic in the active hypogenic karst area of Buda Thermal Karst in Hungary. As an active system, it is a good natural laboratory to study ongoing precipitation processes. Because of anthropogenic influence and the complexity of spring environments, it is challenging to reveal all the governing factors in the process of precipitation. In situ experiments, i.e. artificially controlled natural systems simplify the complexity by adding, excluding or stabilizing influencing parameters during the experiment. CO2 degassing drives changes in the physicochemical parameters of spring waters from the discharge along their flow path. The rate and spatial extension of these changes depend on local hydrogeological, geological, climatic, topographical etc. factors, affecting precipitation processes. In this study, two one-day-long in situ experiments were executed to examine the physicochemical parameter changes of thermal water in a tunnel. The integration of the results with reactive transport models revealed the physicochemical processes of ingassing and degassing and predicted CaCO3 precipitation along the flow path. Small-scale roughness of the channel surface seemed to further influence pH and concentration of HCO3−. After 6 weeks of thermal water flowing, organic precipitate (biofilm) formed close to the discharge and then, with a sharp change, inorganic precipitate (calcite) dominates a bit further from the discharge. In situ experiments and connected numerical simulations revealed the role of CO2 degassing and calcite precipitation in the changes of physicochemical parameters, but organic precipitates also have to be considered near the discharge.
PubDate: 2018-06-01
DOI: 10.1007/s10498-018-9341-2
Issue No: Vol. 24, No. 3 (2018)

• Correction to: The Iodide and Iodate Distribution in the Seto Inland Sea,
Japan
• Authors: Kazuhiko Takeda; Kengo Yamane; Yuuta Horioka; Kazuaki Ito
Pages: 163 - 164
Abstract: In the original publication of the article, Figs. 3 and 4 were interchanged. Now the correct figures have been provided in this erratum.
PubDate: 2018-04-01
DOI: 10.1007/s10498-018-9334-1
Issue No: Vol. 24, No. 2 (2018)

• Hydrogeochemical Processes in a Small Eastern Mediterranean Karst
Watershed (Nahr Ibrahim, Lebanon)
• Authors: N. Hanna; B. Lartiges; V. Kazpard; E. Maatouk; N. Amacha; S. Sassine; A. El Samrani
Abstract: Watersheds located in semiarid areas such as the eastern Mediterranean are particularly sensitive to the impact of climate change. To gain knowledge on the hydrogeochemical processes occurring in the Nahr Ibrahim watershed, a Critical Zone Observatory in Lebanon, we analyze the isotopic composition of the river water as well as the concentrations of the major ions exported (Ca2+, Mg2+, HCO3−, Na+, Cl−, K+, SO42−). Sampling campaigns were conducted from March 2014 to August 2016 to capture contrasting hydrological conditions. The results indicate that the carbonate lithology of the watershed is the predominant source of Ca2+, Mg2+ and HCO3−, whereas the low contents of Na+, Cl−, K+, SO42− mainly originate from sea spray. Except in the headwaters, the Nahr Ibrahim River is oversaturated with respect to calcite and dolomite. During wet seasons, calcite weathering and dolomite weathering contribute in an equivalent manner to the solute budget, whereas during dry seasons, calcite precipitates in the river. The isotopic composition of the river water reveals little seasonal dependency, the groundwater recharge by snowmelt infiltration leading to spring waters depleted in heavier isotopes during the dry seasons. A carbonate weathering rate of about 176 t/km2/year was determined at the outlet of the Nahr Ibrahim watershed. The calculated values of CO2 partial pressure, on average twice the atmospheric pressure, suggest that the river is a significant source of CO2 to the atmosphere (111 t/year).
PubDate: 2018-12-14
DOI: 10.1007/s10498-018-9346-x

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