Applying rare earth elements, Uranium, and 87Sr/86Sr to disentangle structurally forced confluence of regional groundwater resources: The case of the Lower Yarmouk Gorge

The conjoint discussion of tectonic features, correlations of element concentrations, δ18O, δD, and 87Sr/86Sr of groundwater leads to new insight into sources of groundwater, their flow patterns, and salinization in the Yarmouk Basin. The sources of groundwater are precipitation infiltrating into basaltic rock or limestone aquifers. Leaching of relic brines and dissolution of gypsum and calcite from the limestone host rocks generate enhanced salinity in groundwater in different degrees. High U(VI) suggests leaching of U from phosphorite-rich Upper Cretaceous B2 formation. Both very low U(VI) and specific rare earth element including yttrium (REY) distribution patterns indicate interaction with ferric oxyhydroxides formed during weathering of widespread alkali olivine basalts in the catchment area. REY patterns of groundwater generated in basaltic aquifers are modified by interaction with underlying limestones. Repeated sampling over 18 years revealed that the flow paths towards certain wells of groundwater varied as documented by changes in concentrations of dissolved species and REY patterns and U(VI) contents. In the Yarmouk Gorge, groundwater with basaltic REY patterns but high U(VI) and low Sr2+ and intermediate sulfate concentrations mainly ascends in artesian wells tapping a buried flower structure fault system crossing the trend of the gorge

Faulting patterns in the Lower Yarmouk Gorge potentially influence groundwater flow paths

Recent studies investigating groundwater parameters, e.g., heads, chemical composition, and heat transfer, argued that groundwater flow paths in the Lower Yarmouk Gorge (LYG) area are controlled by geological features such as faults or dikes. However, the nature of such features, as well as their exact locations, were so far unknown. In the present paper, we propose a new fault pattern in the LYG area by compiling and revising geological and geophysical data from the study area, including borehole information, geological map cross sections, and seismic data from the southern Golan Heights and northern Ajloun mountains. The presented pattern is composed of strike–slip and thrust faults, which are associated with the Dead Sea transform system and with the Kinnarot pull-apart basin. Compressional and tensional structures developed in different places, forming a series of fault blocks probably causing a non-uniform spatial hydraulic connection between them. This study provides a coarse fault-block model and improved structural constraints that serve as fundamental input for future hydrogeological modeling which is a suggested solution for an enigmatic hydrological situation concerning three riparian states (Syria, Jordan, and Israel) in a water-scarce region. In areas of water scarcity and transboundary water resources, transient 3-D flow simulations of the resource are the most appropriate solution to understand reservoir behavior. This is an important tool for the development of management strategies. However, those models must be based on realistic geometry, including structural features. The study at the LYG is intended to show the importance of such kinds of structural investigations for providing the necessary database in geologically stressed areas without sufficient data. Furthermore, during the hydrogeological investigation, a mismatch with results of pull-apart basin rim fault evolution studies was discovered. We argue that this mismatch may result from the settings at the eastern rim of the basin as the en-echelon changes from pull-apart basins (Dead Sea, Kinnarot, Hula) to a push-up ridge (Hermon)

Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin

Hot and salty waters occur in the surroundings of the Lake Tiberias. Transient numerical simulations of thermally-driven flow without salinity effects show that mixed convection can explain the upsurge of thermal waters through permeable faults and the high temperature gradient in the Lower Yarmouk Gorge (LYG). It turns out that by including salinity effects, the flow patterns differ from those of a purely thermal regime because heavy brines dampen upward buoyant flow and convective cells. Accordingly, the fault permeability had to be increased to restore a good fit with the measured temperatures. This further supports the hypothesis that the high temperature gradient in the LYG is likely due to fractures or faults in that area. The thermohaline simulations also suggest that the derivatives of relic seawater brines are the major source of salinity. Deep brines leaching salt diapirs cannot reach the surface. However, the presence of local shallower salt bodies below the lake can potentially contribute to the salinity of the western spring and well waters, though in very small amount. This is in agreement with geochemical data according to which the major source of the brines of the Tiberias Basin represents seawater evaporation brines. Besides being of importance for understanding the hydrogeological processes that salinize Lake Tiberias, the presented simulations provide a real-case example illustrating large-scale fluid patterns due to only one source of buoyancy (heat) and those that are additionally coupled to salinity

Sources of Salinization of Groundwater in the Lower Yarmouk Gorge, East of the River Jordan

In the Lower Yarmouk Gorge the chemical composition of regional, fresh to brackish, mostly thermal groundwater reveals a zonation in respect to salinization and geochemical evolution, which is seemingly controlled by the Lower Yarmouk fault (LYF) but does not strictly follow the morphological Yarmouk Gorge. South of LYF, the artesian Mukeihbeh well field region produces in its central segment groundwaters, an almost pure basaltic-rock type with a low contribution (<0.3 vol-%) of Tertiary brine, hosted in deep Cretaceous and Jurassic formations. Further distal, the contribution of limestone water increases, originating from the Ajloun Mountains in the South. North of the LYF, the Mezar wells, the springs of Hammat Gader and Ain Himma produce dominantly limestone water, which contains 0.14-3 vol-% of the Tertiary brine, and hence possesses variable salinity. The total dissolved equivalents, TDE, of solutes gained by water/rock interaction (WRI) and mixing with brine, TDEWRI+brine, amount to 10-70% of total salinity in the region comprising the Mukheibeh field, Ain Himma and Mezar 3 well; 55-70% in the springs of Hammat Gader; and 80-90% in wells Mezar 1 and 2. The type of salinization indicates that the Lower Yarmouk fault seemingly acts as the divide between the Ajloun and the Golan Heights-dominated groundwaters

The Hydrogeochemical Stratigraphy of Brines and Its Implications on Water Management in the Central Jordan-Dead Sea Rift Valley, Israel

The exploratory borehole Megiddo-Jezre’el 1 (MJ1) was drilled in Israel, in the Bet She’an Valley which branches out from the Central Jordan Rift. It reached the depth of 5060 m and bottomed within the Upper Triassic Mohilla Fm. Following the increase of groundwater exploitation, the Cl- concentrations increased and ionic ratios changed indicating inflow of Ca2+-Cl- brines, the origins of which were hitherto unknown. Data from the new MJ1 borehole revealed that rock porosities decrease with depth. Lowermost values of about 3% were interpreted from logs in Lower Jurassic and Triassic strata. The highest shut-in pressures were measured in the Upper Jurassic sequence raising the water much higher than the ground surface. Along the drilled section, there is a continuous downward increase in Cl- concentrations in the range of 12-186 g Cl-/l and a very clear stratification of brines. Data from the MJ1 borehole and from other exploration wells indicate that in the subsurface of the area, there are two definite source brines: Triassic brine and the Late Tertiary (so-called) Rift brine. Brines encountered in Jurassic and Cretaceous beds represent ancient mixtures of the two source brines involving various water-rock chemical transformations. Evidence of very high pressures in deep boreholes Devora 2A, Rosh Pinna 1, and MJ1 revealed the existence of a mechanism in which the deep brines are “piston-driven” upwards and possibly also laterally. The ongoing salinization of groundwater in the area is due to the inflow of the Late Tertiary Ca2+-Cl- Rift brines and not that of the Jurassic or Triassic brines. The hydrogeological and hydrochemical data from borehole MJ1 is of major importance for the management of groundwater resources in the Central Jordan Rift Valley and in the adjacent geologically connected areas

Chemical chaperones regulate molecular chaperones in vitro and in cells under combined salt and heat stresses.

Salt and heat stresses, which are often combined in nature, induce complementing defense mechanisms. Organisms adapt to high external salinity by accumulating small organic compounds known as osmolytes, which equilibrate cellular osmotic pressure. Osmolytes can also act as "chemical chaperones" by increasing the stability of native proteins and assisting refolding of unfolded polypeptides. Adaptation to heat stress depends on the expression of heat-shock proteins, many of which are molecular chaperones, that prevent protein aggregation, disassemble protein aggregates, and assist protein refolding. We show here that Escherichia coli cells preadapted to high salinity contain increased levels of glycine betaine that prevent protein aggregation under thermal stress. After heat shock, the aggregated proteins, which escaped protection, were disaggregated in salt-adapted cells as efficiently as in low salt. Here we address the effects of four common osmolytes on chaperone activity in vitro. Systematic dose responses of glycine betaine, glycerol, proline, and trehalose revealed a regulatory effect on the folding activities of individual and combinations of chaperones GroEL, DnaK, and ClpB. With the exception of trehalose, low physiological concentrations of proline, glycerol, and especially glycine betaine activated the molecular chaperones, likely by assisting local folding in chaperone-bound polypeptides and stabilizing the native end product of the reaction. High osmolyte concentrations, especially trehalose, strongly inhibited DnaK-dependent chaperone networks, such as DnaK+GroEL and DnaK+ClpB, likely because high viscosity affects dynamic interactions between chaperones and folding substrates and stabilizes protein aggregates. Thus, during combined salt and heat stresses, cells can specifically control protein stability and chaperone-mediated disaggregation and refolding by modulating the intracellular levels of different osmolytes