Modeling radium distribution in coastal aquifers during sea level changes: The Dead Sea case

Application of radon and radium isotopes to groundwater flow dynamics: An example from the Dead Sea

The Dead Sea is worldwide a major bromine provider for industry with an average concentration of 5.2 g/l of bromide compared to 0.065 mg/l in seawater and with a Cl/Br weight ratio in the Dead Sea water of about 42 compared to around 300 in oceanic water. The origin of the high bromide concentration in the Dead Sea has not yet been adequately clarified. In the course of this study, the bromide concentrations in the different surface and groundwater bodies in Jordan were analyzed and the types of rocks with which these waters were in contact were identified. Analyses carried out up to about 30 years ago and recent analyses confirm the natural origin of bromide in the water and also confirm that the analyzed sources are not polluted by anthropogenic bromide sources. It was found that a variety of these surface and groundwater sources contain high concentrations of bromide which discharges into the Dead Sea and contribute to its high bromide concentration. The present study concludes that the late Cretaceous early Tertiary oil shale deposits form the major source of the bromine species in the surface and groundwater feeding the Dead Sea. Some bromide is also contributed by the Triassic and Jurassic rocks containing evaporate salts containing bromides. Phosphate rocks of late Upper Cretaceous age contribute also with appreciable amounts of bromine species to the different water sources and hence to the Dead Sea water. At present, dissolution and erosion of bromide-rich sediments laid down by the predecessor water bodies of the present Dead Sea such as the Lisan Lake are being transported into the Dead Sea and contribute relatively large amounts of secondary bromide to the Dead Sea water.

The effect of base level changes and geological structures on the location of the groundwater divide, as exhibited in the hydrological system between the Dead Sea and the Mediterranean Sea

The first report, to our knowledge, on the occurrence of filamentous fungi in the hypersaline (340 g salt l-1) Dead Sea is presented. Three species of filamentous fungi from surface water samples of the Dead Sea were isolated: Gymnascella marismortui (Ascomycota), which is described as a new species, Ulocladium chlamydosporum and Penicillium westlingii (Deuteromycota). G. marismortui and U. chlamydosporum grew on media containing up to 50% Dead Sea water. G. marismortui was found to be an obligate halophile growing optimally in the presence of 0.5-2 M NaCl or 10 30% (by volume) of Dead Sea water. Isolated cultures did not grow on agar media without salt, but grew on agar prepared with up to 50% Dead Sea water. This suggests that they may be adapted to life in the extremely stressful hypersaline Dead Sea.

After a prolongued period of stratification (about 300 years) the Dead Sea overturned in 1979 and again in 1982. Its waters became saturated with respect to halite and the massive precipitation of halite which occurred in winter 1982/83 has been monitored. We followed the fate of the heavy metals during this period of physical and chemical changes. The concentrations of Zn, Cd, Pb and Cu in the Dead Sea waters have been measured by anodic stripping voltammetry (ASV) which provided sensitive measurement of these elements after a minimal pretreatment of the samples (dilution 1: 1 and acidification). In the meromictic lake (prior to 1979), the concentrations of all four elements were larger in the deep anoxic layers. With the onset of halite precipitation a decline in their concentrations was observed. Most dramatic was the decrease in Cd, which practically disappeared from the water column in 1985. The coprecipitation of heavy metals with halite — collected by sediment traps in 1983 — was examined, as well as that of older halite recovered from a sediment core. Although concentrations of heavy metals were somewhat larger in recent halite, all halite samples had the same coprecipitation pattern: the concentration of Pb was the largest, followed by Cd, and that of Cu was the smallest. The apparent distribution coefficient was larger for Cd than for Pb. We estimated the amount of Cd which may have accompanied the deposition of halite during 1983–1985; it is compatible with its observed disappearance from the water column in 1985. The amounts of Pb and of Zn which are missing from the Dead Sea of 1985 are much larger than can be accounted for by coprecipitation with halite. A possible explanation is that the formation of halite crystals may have enhanced settling of particulates which in turn, may have scavenged Pb and Zn from the Dead Sea waters. Cu seems to be much less affected by the physical and chemical events which occurred in the Dead Sea during 1976–1985.

Atmospheric mercury depletion events at the Dead Sea: Spatial and temporal aspects

Relationships between lake-level changes and water and salt budgets in the Dead Sea during extreme aridities in the Eastern Mediterranean

The role of magnesium in drownings in the dead sea

The image of the Dead Sea as a body of water which by its very nature is hostile to human activities persisted for over 2000 years [1]. One of the aspects of this view was the often made claim that no boats can ply the lake water. To quote two examples out of many others, Pompeius Trogus (63 B.C.-14 A.D.) claimed that the Dead Sea is inherently antagonistic to nonliving material and therefore any ship which sails on the lake would sink [2]. Justin (7th century A.D.) declared that Dead Sea water will not bear navigable vessels because "whatsoever is without life sinks downright to the bo t tom" [2]. This hostile image contrasts markedly with historical evidence which indicates the importance of the Dead Sea as a t rade artery. The shortest, and safest, road from the fertile land of Moab, overlooking the eastern coast of the Dead Sea, to Judea was by sea. Local products of the area were also transported over the lake [2]. For example, during the Crusader period, sugar, dates, and other agricultural products were moved by boats f rom Segor (EsSail) in the south to the Kalia area in the north. Float ing asphalt blocks, a major trade commodity , were collected by boats and exported to Egypt [3, 4]. According to letters found a few years ago in caves in the escarpment overlooking the western coast of the lake, the rebels of Bar Kochba (2nd Century, A.D.) were supplied by boats landing in Ein Gedi [2].

Hydrochemical processes in the lower Jordan valley and in the Dead Sea area

At the Dead Sea spas, which are 400 m below sea level, both the ultraviolet radiation from the sun and the mineral-rich waters of the lake have special features. The separate influence of these two factors was studied in 81 patients with psoriasis. The condition was assessed during 4 weeks of treatment using the psoriasis area and severity index (PASI). In subjects who only bathed in Dead Sea water the improvement was 28%, in those who only sunbathed it was 73%, and in those who did both it was 83%. The main therapeutic factor was thus shown to be sun exposure, possibly enhanced by bathing in Dead Sea water. Similar degrees of improvement in spring, summer and autumn led to speculation about the optimum dose of solar radiation needed.

To study biological phenomena in the Dead Sea and to simulate the effects of mixing Dead Sea water with Red Sea water, experimental mesocosms were operated at the Dead Sea Works at Sedom, Israel. Dense communities of red halophilic archaea developed in mesocosms filled with 80 % Dead Sea water and 20 % Red Sea water after enrichment with phosphate. The most common type of colonies isolated from these brines belonged to the genus Halorubrum. A few white-pinkish opaque colonies contained pleomorphic flat cells with gas vesicles. Three strains isolated from the latter colonies were characterized in depth. Their 16S rRNA gene sequences showed only 91 % similarity to the closest cultured relative (Haloferax mediterranei), indicating that the new strains represent a novel species of a new genus. The name Haloplanus natans gen. nov., sp. nov. is proposed for this novel organism. The type strain of Haloplanus natans is RE-101(T) (=DSM 17983(T)=JCM 14081(T)).

<p>The drainage basin of the Dead Sea is the largest hydrological system in the Levant and spans across the boundary between the sub-humid to semi-arid Mediterranean and the arid to hyper-arid Saharo-Arabian climate zones. As a terminal lake, precipitation changes due to climatic variations result in extensive fluctuations of lake level and sediment deposition.</p><p>A unique sediment record from the deepest part of the Dead Sea Basin was obtained as part of the ICDP Dead Sea Deep Drilling Project. Here we analyze the partially annually laminated sediments of Core 5017-1-A between 88.5-99.2 m core depth, which comprise the period between ~16.5 and ~11 ka and document a lake level drop of ca 160 m. In the sediments of Core 5017-1-A, this marks the transition from MIS2 aad (alternating aragonite and detritus) sediments to MIS1 halite deposits and ld (laminated detrital marl) sediments, coinciding with increased drying in the Dead Sea watershed.</p><p>Microfacies analyses show the occurrence of several lithological facies that accumulated during MIS2: aad, gd (massive gypsum deposit within marl), native sulfur concretions (associated with greenish colored aad), mtd (mass-transport deposits, typically graded) and homogenites consisting of clay and silt. Further, flood layers have been identified, potentially indicating rainstorms associated with specific eastern Mediterranean synoptic systems. To complement the microfacies analyses, XRF scanning provides continuous Ti/Ca and S/Ca records to reconstruct relative detrital input and gypsum occurrence, respectively. Additionally, to study potential early signs of hydroclimatic change, the deep lake sediments are correlated to the Lisan Formation of the marginal Masada outcrop using distinct gypsum marker layers, indicative of pronounced lake level drops. However, due to a significant lake level decline, the Masada outcrop sediments terminate at around 14.5 ka and the subsequent lake level lowering is solely recorded in the deep lake sediments.</p><p>This study was funded by the German Science Foundation (DFG Grant BR 2208/13-1/-2). Further, it is a contribution to the Helmholtz Association (HFG) climate initiative REKLIM Topic 8 “Abrupt climate change derived from proxy data”.</p>

Unique gypsum structures: large capes (termed “gypsum deltas”) and small pitted gypsum mounds are exposed along the western shores of the currently retreating Dead Sea, the hypersaline terminal lake in the Dead Sea Basin. The gypsum deltas were formed during time intervals of low lake stands (∼420 ± 10 m below mean sea level), when sulfate‐rich Ca chloride brines discharged from the coastal aquifer via saline springs, mixed with the Dead Sea brine and precipitated the gypsum (outsalting process). The ages of formation of the gypsum structures coincide with times of North Atlantic cooling events and grand solar minima suggesting a direct impact of the latter on the Dead Sea hydrology and high sensitivity of the regional hydrology (controlling lake level) to global solar‐related events. The temporal occurrence and numbers of the gypsum structures appear to follow the Hallstatt Cycle that approaches minima at ∼3,000–2,000 years before present.

Despite its purported importance, previous studies of the influence of sea-level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of the sea water intrusion response to sea-level rise has not been reported. In this study, a simple conceptual framework is used to provide a first-order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea-level rise. Two conceptual models are tested: (1) flux-controlled systems, in which ground water discharge to the sea is persistent despite changes in sea level, and (2) head-controlled systems, whereby ground water abstractions or surface features maintain the head condition in the aquifer despite sea-level changes. The conceptualization assumes steady-state conditions, a sharp interface sea water-fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea-level rise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea-level rise. This study has highlighted the importance of inland boundary conditions on the sea-level rise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable.