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Liu, F., Wang, S., Wang, L., Shi, L., Song, X., Yeh, T. - C. J., et al. (2019). Coupling hydrochemistry and stable isotopes to identify the major factors affecting groundwater geochemical evolution in the Heilongdong Spring Basin, North China. Journal of Geochemical Exploration, 205.
Abstract: Understanding the interference of natural processes and anthropogenic activities in geochemical evolution of groundwater is vital for groundwater sustainable management in water-stressed regions. This study is devoted to the identification of the main factors controlling the evolution of groundwater chemistry by the combined use of hydrogeochemical indicators along with isotope tracers in the Heilongdong Spring Basin, North China. Thirty-nine groundwater samples and twelve surface water samples were collected, and major ions and stable isotopes were measured during the two campaigns (December 2017 and August 2018). The isotope approach indicates that the groundwater is recharged by precipitation infiltration after evaporation, and interacts with surface water along preferential flow paths in fault zones and karst conduits. Currently, the main chemical facies of groundwater evolve from Ca-HCO3 and Ca-Mg-HCO3 types with low TDS, through Ca-Mg-HCO3-SO4 and Ca-HCO3-SO4 types with moderate TDS, to Ca-SO4, Ca-SO4-Cl and CaCl types with high TDS. Apart from natural processes (involving dissolution/precipitation of minerals, cation exchange, and evaporation) regulating the groundwater quality, the stagnant zones also play a crucial role in the formation of severe localized nitrate contamination. The deterioration in groundwater quality can be attributed to anthropogenic factors (including the change in groundwater exploitation, the leaching of solid waste, and the overuse of agricultural fertilizers). The high loads of agricultural fertilizers in irrigation return flows are likely to be the main contributor of the dissolved nitrate in groundwater. The findings of this work not only have important implications for groundwater sustainable utilization, but also could serve as a template for other rapidly industrialized and water-stressed regions.
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Llopis-Albert, C., Merigó, J. M., & Xu, Y. (2016). A coupled stochastic inverse/sharp interface seawater intrusion approach for coastal aquifers under groundwater parameter uncertainty. Journal of Hydrology, 540, 774–783.
Abstract: This paper presents an alternative approach to deal with seawater intrusion problems, that overcomes some of the limitations of previous works, by coupling the well-known SWI2 package for MODFLOW with a stochastic inverse model named GC method. On the one hand, the SWI2 allows a vertically integrated variable-density groundwater flow and seawater intrusion in coastal multi-aquifer systems, and a reduction in number of required model cells and the elimination of the need to solve the advective-dispersive transport equation, which leads to substantial model run-time savings. On the other hand, the GC method allows dealing with groundwater parameter uncertainty by constraining stochastic simulations to flow and mass transport data (i.e., hydraulic conductivity, freshwater heads, saltwater concentrations and travel times) and also to secondary information obtained from expert judgment or geophysical surveys, thus reducing uncertainty and increasing reliability in meeting the environmental standards. The methodology has been successfully applied to a transient movement of the freshwater-seawater interface in response to changing freshwater inflow in a two-aquifer coastal aquifer system, where an uncertainty assessment has been carried out by means of Monte Carlo simulation techniques. The approach also allows partially overcoming the neglected diffusion and dispersion processes after the conditioning process since the uncertainty is reduced and results are closer to available data.
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Magaritz, M., Nadler, A., Kafri, U., & Arad, A. (1984). Hydrogeochemistry of continental brackish waters in the southern Coastal Plain, Israel. Chemical Geology, 42(1), 159–176.
Abstract: The southern Coastal Plain in Israel incorportates a transitional fringe of the desert in which three different chemical types of groundwater are found: (1) near-surface waters from springs along the Besor River course: (2) shallow- to moderate-depth waters from the slightly westward-dipping Pleistocene coastal aquifer (this aquifer, which consists of sandstone layers of the Kurkar Group, is recharged in the Coastal Plain); and (3) deep waters of the westward-dipping Upper Cretaceous Judea Group carbonates, which are recharged in the mountains in the east. A thick aquiclude of Upper Cretaceous-Tertiary rocks separates the Judea Group aquifer from the overlying coastal aquifer in the southern Coastal Plain. Isotopically light oxygen and depleted deuterium characterize the Judea Group waters, as expected from high-altitude recharge. The isotopic composition of the Coastal Plain waters is variable, but for the most part enriched in 18O and D. Within the southern Coastal Plain aquifer a southern subgroup comprises waters more depleted in heavy isotopes than those of either the northern or eastern subgroups. The Besor waters are isotopically similar to the Judea Group waters, reflecting their origin in the mountain region, and flow through the surficial river gravels and sands. It is suggested that leakage of the Besor waters into the underlying southern Coastal Plain aquifer results in mixing of the two water types. The most prominent chemical feature characterizing the groundwater of the southern Coastal Plain is Na+Cl− \textgreater 1. This Na+Cl− ratio can be maintained only by a continuous input from a non-marine source of Na. The most plausible source of this Na is the dissolution of feldspar derived from the windblown loess deposits which cover the area and/or leaching of trona minerals found in the unsaturated zone, combined with base-exchange processes.
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Moral, F., Cruz-Sanjulián, J. J., & Olías, M. (2008). Geochemical evolution of groundwater in the carbonate aquifers of Sierra de Segura (Betic Cordillera, southern Spain). Journal of Hydrology, 360(1), 281–296.
Abstract: Sierra de Segura (Betic Cordillera), with a total area of over 3000km2, is the source of the two principal rivers in southern Spain, the Guadalquivir and the Segura. Due to the orographic effect of these mountains, precipitations are considerably more abundant than in nearby lowland areas, where the climate is semi-arid. Sierra de Segura is constituted of Mesozoic and Cenozoic sedimentary rocks, among which there are thick limestone–dolomitic formations which have given rise to extensive outcrops of permeable materials. In geomorphological terms, there is a large plateau intensively karstified that constitutes the main recharge area. Discharge takes place via a large number of springs, of which the 50 most important add up to a mean spring flow of about 13,500l/s. The active geochemical processes in aquifers of Sierra de Segura, with their corresponding time sequence, are: dissolution of CO2, dissolution of calcite, incongruent dissolution of dolomite, dedolomitization, exsolution of CO2, and precipitation of calcite. More evolved water has higher temperature, magnesium content and Mg/Ca ratio; therefore, these parameters can be utilised as indicators of the degree of hydrochemical evolution. In addition, a good correlation between water temperature and magnesium concentration (or Mg/Ca ratio) indicates that an increase in temperature accelerates the kinetics of the dissolution of dolomite. Finally, the distribution of the temperatures in the vadose zone, determined by atmospheric thermal gradient, implies an apparent stratification of the predominant hydrochemical processes and of the groundwater physical and chemical characteristics.
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Nadler, A., Magaritz, M., & Mazor, E. (1980). Chemical reactions of sea water with rocks and freshwater: Experimental and field observations on brackish waters in Israel. Geochimica et Cosmochimica Acta, 44(6), 879–886.
Abstract: Four major processes are observed to take place in the coastal aquifer of Israel, detectable even in the short times of water contact with the carbonate-containing host rocks. Three are chemical reactions, Ca2+-Mg2+ exchange, Na+-Ca2+ or Na+-Mg2+ base exchange, SO2−4 reduction and the fourth is dilution by freshwater. These reactions and their effects on the chemical composition of the waters were demonstrated experimentally. The range of chemical changes observed in the laboratory experiments overlap the range of the studied natural waters. This indicates that simulation of geologically long-term rock-water interaction could be achieved in laboratory experiments even at low temperatures.
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