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Author Pacheco, F.A.L.; Szocs, T.
Title “Dedolomitization reactions” driven by anthropogenic activity on loessy sediments, SW Hungary Type Journal Article
Year 2006 Publication Applied Geochemistry Abbreviated Journal
Volume 21 Issue 4 Pages 614-631
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Abstract 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 Ca and SO4. The Ca 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\textgreatercalcite\textgreaterplagioclase\textgreaterK-feldspar, at odds with widely accepted sequences of weatherability where calcite is the first mineral in the weathering sequence. 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 Ca vs. SO4 and Mg vs. SO4 trends are also compatible with homologous trends resulting from “dedolomitization reactions”.
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ISSN 0883-2927 ISBN Medium
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Call Number THL @ christoph.kuells @ Pacheco2006 Serial 35
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Author Sebben, M.L.; Werner, A.D.; Graf, T.
Title Seawater intrusion in fractured coastal aquifers: A preliminary numerical investigation using a fractured Henry problem Type Journal Article
Year 2015 Publication Advances in Water Resources Abbreviated Journal
Volume 85 Issue Pages 93-108
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Abstract Despite that fractured coastal aquifers are widespread, the influence of fracture characteristics on seawater intrusion (SWI) has not been explored in previous studies. This research uses numerical modelling in a first step towards understanding the influence of fracture orientation, location and density on the extent of seawater and accompanying patterns of groundwater discharge in an idealised coastal aquifer. Specifically, aquifers containing single fractures or networks of regularly spaced fractures are studied using modified forms of the Henry SWI benchmark problem. The applicability of equivalent porous media (EPM) models for representing simple fracture networks in steady-state simulations of SWI is tested. The results indicate that the influence of fractures on SWI is likely to be mixed, ranging from enhancement to reduction in seawater extent and the width of the mixing zone. For the conceptual models considered here, vertical fractures in contact with the seawater wedge increase the width of the mixing zone, whereas vertical fractures inland of the wedge have minimal impact on the seawater distribution. Horizontal fractures in the lower part of the aquifer force the wedge seaward, whereas horizontal fractures located within the zone of freshwater discharge enhance the wedge. Inclined fractures roughly parallel to the seawater-freshwater interface increase the landward extent of seawater and fractures perpendicular to the interface inhibit the wedge. The results show that EPM models are likely inadequate for inferring salinity distributions in most of the fractured cases, although the EPM approach may be suitable for orthogonal fracture networks if fracture density is high and appropriate dispersivity values can be determined.
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ISSN 0309-1708 ISBN Medium
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Call Number THL @ christoph.kuells @ Sebben2015 Serial 37
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Author Vengosh, A.; Rosenthal, E.
Title Saline groundwater in Israel: its bearing on the water crisis in the country Type Journal Article
Year 1994 Publication Journal of Hydrology Abbreviated Journal
Volume 156 Issue 1 Pages 389-430
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Abstract One of the major causes for the deterioration of water quality bearing heavily on the water crisis in Israel is the ongoing contamination of its water resources by saline water bodies. The present paper reviews the geochemical processes forming saline water, lists and explains certain chemical and isotopic parameters which enable understanding these processes and describes the saline groundwater bodies and various salinization phenomena occurring in the country’s various aquifers. Deterioration of groundwater in Israel is caused by numerous natural processes such as encroachment of sea water, migration of connate, highly pressurized brines penetrating into fresh groundwater, by subsurface dissolution of soluble salts originating in surrounding country rocks and by water-rock interaction. In addition to sea water, two saline water bodies were identified as the main factors causing salinization of fresh groundwater: (a) Ca-chloride brines encountered in the Jordan-Dead Sea Rift Valley, in various parts of the Negev and of the Coastal Plain, and (b) Na-chloride saline water identified in the subsurface of the Negev and in the southern part of the Coastal Plain. Intensive exploitation of groundwater in Israel has disturbed the natural equilibrium which prevailed between fresh and saline water. The newly established groundwater flow regimes have facilitated the migration of saline water bodies, their participation in the active hydrological cycle and the progressive contamination of fresh groundwater. These processes which were not anticipated by planners and water resources managers emphasize that large-scale groundwater exploitation was undertaken without giving sufficient consideration to the occurrence and subsurface migration of saline water and brines.
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ISSN 0022-1694 ISBN Medium
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Notes Approved no
Call Number THL @ christoph.kuells @ Vengosh1994 Serial 39
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Author Shyu*, G.; Cheng, B.; Chiang, C.; Yao, P.; Chang, T.
Title Applying factor analysis combined with kriging and information entropy theory for mapping and evaluating the stability of groundwater quality variation in Taiwan Type Journal Article
Year 2011 Publication Int. J. Environ. Res. Public Health Abbreviated Journal
Volume 8 Issue Pages 1084-1109
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Call Number CUT @ phaedon.kyriakidis @ Shyu2011 Serial 123
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Author Xu, J.; Li, W.; Hong, Y.; Wei, C.; Tang, J.
Title A quantitative assessment on groundwater salinization in the Tarim River lower reaches, Northwest China Type Journal Article
Year 2014 Publication Sci. Cold Arid. Reg. Abbreviated Journal
Volume 6(1) Issue Pages 44-51
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Call Number CUT @ phaedon.kyriakidis @ Xu2014 Serial 126
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