34S and 18O in dissolved sulfate as tracers of hydrogeochemical evolution of the Triassic carbonate aquifer exposed to intense groundwater exploitation (Olkusz–Zawiercie region, southern Poland) (original) (raw)
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Sources and impact of sulphate on groundwaters of Triassic carbonate aquifers, Upper Silesia, Poland
Journal of Hydrology, 2013
Sulphur isotopes Oxygen isotopes Carbonate aquifer Linear mixing model Monte Carlo method s u m m a r y Groundwater within the unconfined or semi-confined parts of Triassic carbonate aquifers in Upper Silesia (Poland) contains high concentrations of sulphate (up to 290 mg/L), sometimes in excess of drinking water limits (>250 mg/L). To assess the influence of different possible sulphate sources, isotopic analyses of S and O were performed on groundwater sulphate and potential sulphate sources and combined with literature data. Three dominant sources of sulphate were delineated, based on the geological and literature study and supported by the mixing relations between inverse concentration of sulphate and its isotopic compositions. These sources are: (i) sulphate from rainfall; (ii) weathering of sulphide minerals in ore deposits in the aquifer-forming carbonate rocks; (iii) dissolution of sulphate evaporites in the Triassic sequence. Fortunately these three sources have distinctive S and O isotope compositions and thus their contributions to the total dissolved sulphate could be estimated. The application of linear mixing models for three sources in the dual isotope system allowed the impact of the three different sulphate sources on particular parts of the aquifers to be calculated. The average isotopic composition of sulphate in abstracted groundwater indicates that the most important source of sulphate is sulphide weathering, contributing about 50% of total sulphate. The second most significant source of sulphate input is rainfall and it is characterised by a mean contribution of 30%. Application of Monte Carlo analysis that incorporates the full variability in distributions of isotopic compositions for the three sources and all mixing fractions between them gave the most probable ranges of the dissolved in groundwater sulphate. This analysis indicated that the proportion of sulphate derived by sulphide oxidation is comparable with the estimations based on linear models. This study has shown that the water quality of these important groundwater resources is under threat from both natural sources, i.e. metal sulphide oxidation and gypsum dissolution. Analysis of the mathematical models analysis shows that the first process is the predominant source of sulphate in groundwater. However, the highest concentrations of dissolved sulphate are positively correlated with the increasing proportion of sulphate derived from gypsum dissolution. Moreover, one should keep in mind that natural processes might be anthropogenically accelerated due to variable water demands and groundwater abstraction. Eventually, the statistically secondorder source of sulphate -rainfall might contain surface-derived contaminants, and its contribution to the total load of sulphate might indirectly indicate the vulnerability of aquifers for the pollution.
Applied Geochemistry, 2008
The paper presents the results of a geochemical and isotopic study of acidic pond water in the abandoned Podwiśniówka quarry (Poland). The scope of investigations also encompassed mineralogical and isotopic studies of pyrite and related supergene minerals. Compared to similar sites throughout the world, the pit pond water examined is characterized by a very low pH averaging 2.64 ± 0.33 and simultaneously very low concentrations of SO 2À 4 (geometric mean of 237 ± 57 mg L À1 ), Fe(II) (4.8 ± 3.4 mg L À1 ), Fe(III) (10.0 ± 6.2 mg L À1 ) and other trace elements. This acidity has been generated by complex processes of As-rich pyrite oxidation combined primarily with hydrolysis, precipitation, and transformation of Fe oxyhydroxysulfates and oxyhydroxides into goethite. The specific mineralogy of ore and gangue minerals, but especially the lack of acid-buffering constituents, has additionally contributed to the very low pH and element concentrations. Of the toxic elements, the high content of As (1111-1879 mg kg À1 ) in the western part of pit pond sediment may be of great concern, especially when using lime as a neutralizing agent of the acidic water. The d 34 S of soluble SO 4 varied from À19.8‰ to À11.1‰ and was different from that of efflorescent sulfates (À25.7‰ to À25.4‰) and host pyrite (À25.4 ± 2.5‰). The comparison of the d 18 O-SO 2À 4 (À2.0 ± 1.2‰) and d 18 O-H 2 O (À6.2 ± 3.5‰) values indicated that the pyrite underwent bacterially catalyzed oxidation by two natural oxidants, primarily by Fe 3+ and to a lesser extent O 2 .
2012
The analysis of sulphates content in groundwater has been based on results of the regional and local groundwater quality monitoring performed in the area of the Olkusz and Bytom regions. There are situated still active and abandoned Zn-Pb ores mines. These areas have been subjected to long-lasting intensive drainage, which has caused significant changes of hydrogeochemical conditions in Triassic aquifer. The results of these changes are mainly: high concentrations of sulphates (up to more than 5000 mg/dm3) in groundwater of the Triassic karst-fractured aquifers in both regions. Numerous industrial and communal waste sites were constructed directly on the area without any protective measures. These waste sites, particularly in recharge areas, are an additional source of sulphates noticed in groundwater. So the final contents of sulphates observed in groundwater in these areas is the result of an overlapping negative impact of both above mentioned factors.
2007
Groundwater in the Carboniferous–Permian sedimentary aquifer in the vicinity of Unislaw Śląski–Sokolowsko (Intra-Sudetic Basin, the Sudetes, SW Poland) manifests spatial chemical diversity. The water chemistry varies from fresh calcium-magnesium-bicarbonate groundwater at the recharge area to calciumsodium-sulphate mineral water downwards the basin. Geochemical mass balance modelling confirms that the main chemistry features of the sulphate mineral water are controlled by dedolomitization and calcium common-ion effects. Congruent dissolution of gypsum promotes incongruent dissolution of dolomite with calcite precipitation. Cation exchange between Ca 2+ (and Mg 2+ ) solutes and Na + (and K + ) also takes place. The sulphate mineral water shows elevated concentrations of numerous trace elements. Iron, zinc and manganese originate from dissolution of carbonates (dolomite and/or siderite) and/or sulphides. The hydrogeological system studied should be considered as a series of individual...
Applied Geochemistry, 2002
Sulfur and O isotope analyses of dissolved SO 4 were used to constrain a hydrogeological model for the area overlying the Gorleben-Rambow Salt Structure, Northern Germany. Samples were collected from 80 wells screened at different depth-intervals. The study area consists of a set of two vertically stacked aquifer systems. Generally, the isotope data show a good spatial correlation, outlining well-defined groundwater zones containing SO 4 of characteristic isotopic composition. Highly saline waters from deeper parts of the lower aquifer system are characterized by rather constant SO 4 isotopic compositions, which are typical of Permian Zechstein evaporites (d 34 S=9.6-11.9%; d 18 O=9.5-12.1%). Above this is a transition zone containing ground waters of intermediate salinity and slightly higher isotopic values (average d 34 S=16.6%; d 18 O=15.3%). The confined groundwater horizon on the top of the lower aquifer system below the low permeable Hamburg Clays is low in total dissolved solids and is characterized by an extreme 34 S enrichment (average d 34 S=39.1%; d 18 O=18.4%), suggesting that bacterially mediated SO 4 reduction is a dominant geochemical process in this zone. Two areas of distinct isotopic composition can be identified in the shallow ground water horizons of the upper hydrogeological system. Sulfate in groundwaters adjacent to the river Elbe and Lo¨cknitz has a typical meteoric isotopic signature (d 34 S=5.2%; d 18 O=8.2%), whereas the central part of the area is characterized by more elevated isotopic ratios (d 34 S=12.7%; d 18 O=15.6%). The two major SO 4 pools in the area are represented by Permian seawater SO 4 and a SO 4 of meteoric origin that has been mixed with SO 4 resulting from the oxidation of pyrite. It is suggested that the S-isotope compositions observed reflect the nature of the SO 4 source that have been modified to various extent by bacterial SO 4 reduction. Groundwaters with transitional salinity have resulted from mixing between brines and low-mineralized waters affected by bacterial SO 4 reduction.
Journal of Geochemical Exploration, 2002
A detailed chemical study of groundwater was carried out to elucidate the processes controlling the oxidation and dissolution of sulphide minerals at two massive sulphide deposits in the Iberian Pyrite Belt (IPB), i.e. the mined La Zarza deposit and the unmined Masa Valverde deposit. It was found that major-element compositions varied according to the hydrological regime, La Zarza being in a relatively high area with groundwater recharge (and disturbance due to the human factor) and Masa Valverde being in a relatively low area with groundwater discharge. The variations mainly concern pH, Eh, SO 4 and Na concentrations. Metal concentrations were determined (a) by ICP-MS after filtration, and (b) in some cases by voltammetric measurement of Cu, Pb, Zn, Cd and Mn using the Voltammetric In situ Profiling (VIP) System, which allows detection of only the mobile fractions of trace elements (i.e., free metal ions and small labile complexes a few nanometers in size). If one compares the results obtained by each of the two methods, it would appear that the groundwater shows significant enhancement of metal solubility through complexing with organic matter and/or adsorption onto colloids and/or small particles. In areas of sulphide oxidation, however, this solubility enhancement decreases according to Cu > Zn>Cd>Pb. Under very low redox conditions, the attained metal concentrations can be several orders of magnitude (up to 10 8 -10 9 for Cu and 10 2 -10 3 for Pb) larger than those expected from equilibrium with respect to sulphide minerals as calculated with the EQ3NR geochemical code; Zn concentrations, however, are close to equilibrium with respect to sphalerite. The implication of these results is discussed with respect both to mineral exploration and to environmental issues. D
Environmental Geology, 2009
In 2005 and 2006, hydrogeochemical study was carried out in the bipartite Wiśniówka Mała pit lake of the Holy Cross Mountains (south-central Poland). This is the largest acidic water body in Poland. This report presents the element concentrations in the water and sediment, stable sulfur and oxygen isotope ratios in the soluble sulfates, and stable oxygen isotope ratio in the water. The scope of the investigation also encompassed mineralogical examinations (scanning electron microscope, X-ray diffraction) of the sediment. The results of this study show that there is a spatial and temporal variability in concentrations of most elements and sulfur isotope ratios in the examined pit lake. The water of the western pond displayed a lower pH with a mean of 3.73 and higher conductivity (390 lS cm -1 ) as well as higher concentrations of sulfates (156 mg L -1 ) and most of the cations and anions. The concentrations of Fe 2+ and Fe 3+ averaged 0.8 and 0.4 mgÁL -1 . In contrast, the eastern pond water revealed a higher pH (mean of 4.36), lower conductivity (293 lS cm -1 ) and lower sulfate (90 mg L -1 ) and trace metal levels. Similar variations were recorded in the stable sulfur isotope ratios. The d 34 S V-CDT (SO 4 2-) values in the water of the western pit pond were in the range of -6.7 to -4.6% (mean of -5.6%), whereas that in the eastern pit pond ranged from -2.2 to -0.9% (-1.6%). The alkalinity of the entire lake water was below 0.1 mgÁL -1 CaCO 3 . No distinct difference in the d 18 O V-SMOW (SO 4 2-) was noted between the western and eastern pit ponds. Compared to the Purple Pond in the Sudetes (Poland) and similar sites throughout the world, the examined pit lake is highlighted by distinctly low concentrations of sulfates, iron and other trace metals. Based on this and other studies performed in the Holy Cross Mountains, a conclusion can be drawn that the SO 4 2in the Wiśniówka Mała pit lake water is a mixture of SO 4 2derived from the following sources: (1) pyrite oxidation (especially in the western pond water), (2) leaching of soluble sulfates from soils and waste material, as well as subordinate deposition of airborne sulfate precipitation.
Austrian Journal of Earth Sciences, 2016
In the Upper Kauner Valley of the Tyrolean Central Alps in Austria, some of the slopes, consisting of crystalline bedrock covered by Quaternary deposits, host groundwater of remarkable chemical composition. The bedrock consists mainly of a thick paragneiss series with intercalations of orthogneiss and amphibolite belonging to the Ötztal-Stubai Basement Complex. These metamorphic rocks are ubiquitously fractured and the fracture surfaces are coated with Fe-(hydr-)oxides and chlorite but also carbonates. Sul phides occur as dispersed accessory crystals and locally as small ore deposits. During the Quaternary, the valley floor, slopes, and cirques were covered by clastic sediments of differing thicknesses. A striking feature of the valley is that the slopes have been affected by different types of mass movements (rockfalls, debris flows and deep-seated rockslides). Data from extensive (hydro)geological field surveys, tunnels (exploration drift and water conduction galleries) and exploration drillings indicate that the groundwater preferentially flows within zones of highly weathered bedrock (i.e. the saprolite), brittle fault and fracture zones, deep-seated rockslides, and in the conductive Quaternary deposits, i.e. the talus, colluvium, debris flow and alluvial deposits. Interestingly, unusually high amounts of total dissolved solids (>1000 mg / l) were measured in some spring waters. Tritium and δ 18 O values indicate short residence times (<5 years) and the analysis of δ 18 O and δ 2 H data shows that the groundwater is of meteoric origin and that no fractionation or evaporation processes, leading to increased mineralisation, have taken place. Ca and Mg are the dominant cations and SO 4 and HCO 3 are the major anions present. Data correlation shows that the electric conductivity (EC) of the waters increases with increasing Ca, Mg and SO 4 concentration, but not with HCO 3. Low δ 34 S values indicate that the dissolved sulphate can be attributed to the oxidation of sulphides. Accordingly, the dissolution of carbonate fracture fillings and the oxidation of pyrite and other sulphides are regarded as the main processes responsible for the mineralised groundwater in the study area. Im hinteren Kaunertal der Tiroler Zentralalpen, welches aus metamorphen Gesteinen aufgebaut und durch quartäre Ablagerungen bedeckt wird, tritt Grundwasser von bemerkenswerter chemischer Zusammensetzung auf. Das Festgestein ist Teil des Ötztal-Stubai-Komplexes und besteht vorwiegend aus mächtigen Paragneis-Serien mit Einschaltungen aus Orthogneis und Amphibolit. Diese metamorphen Gesteine treten durchgehend geklüftet auf. Die Kluftflächen weisen Fe-(hydr-)oxide und Chlorit sowie Karbonat überzüge auf. Sulfide treten einerseits feinverteilt akzessorisch und andererseits als kleine Erzkörper auf. Im Quartär wurden klastische Sedimente unterschiedlicher Mächtigkeiten im Talboden, auf den Hängen und in hochgelegenen Karen abgelagert. Ein besonderes Merkmal des Tales sind verschiedene Typen von Massenbewegungen (Steinschlag, Muren und tiefgründige Felsgleitungen), die entlang der Hangflanken auftreten. Daten von umfassenden (hydro)geologischen Gelände-und Tunnelaufnahmen (Erkundungsstollen und Wasserbeileitungsstollen) zeigen, dass das Grundwasser vorwiegend in stark verwitterten Bereichen des Festgesteins (Saprolit), in spröden Störungs-und Zerlegungszonen, in tiefgründigen Massenbewegungen und den durchlässigen quartären Ablagerungen, wie alluvialen Sedimenten, Murschutt, Hangschutt und kolluvialen Schuttkegeln, fließt. Interessanterweise wurden ungewöhnlich hohe Gesamtionenkonzentrationen (>1000 mg / l) in einigen der natürlichen Quellwässer gemessen. Die Tritium und δ 18 O Gehalte deuten auf kurze Verweilzeiten (<5 Jahre) hin. δ 18 O und δ 2 H Daten zeigen, dass das Grundwasser meteorischen Ursprungs ist und keine Fraktionierung oder Evaporation stattgefunden haben, welche die Mineralisation erhöhen würden. Ca und Mg sind die dominierenden Kationen, und SO 4 und HCO 3 treten als Hauptanionen auf. Eine Korrelation der Daten zeigt, dass die elektrische Leitfähigkeit des Wassers mit zunehmenden Ca, Mg und SO 4 Werten, jedoch nicht mit zunehmender HCO 3 Konzentration steigt. Niedrige δ 34 S Werte weisen darauf hin, dass das gelöste Sulfat aus der Oxidation von Sulfiden stammt. Die Lösung von karbonatischen Kluftfüllungen und die Oxidation von Pyrit und anderen Sulfiden werden somit als Hauptprozesse für die hohe Mineralisation des Grundwassers im Untersuchungsgebiet angesehen.