SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Dead Sea

496

Computer imaging techniques are commonly used to preserve and share readable manuscripts, but capturing writing locked away in ancient, deteriorated documents poses an entirely different challenge. This software pipeline-referred to as “virtual unwrapping”-allows textual artifacts to be read completely and noninvasively. The systematic digital analysis of the extremely fragile En-Gedi scroll (the oldest Pentateuchal scroll in Hebrew outside of the Dead Sea Scrolls) reveals the writing hidden on its untouchable, disintegrating sheets. Our approach for recovering substantial ink-based text from a damaged object results in readable columns at such high quality that serious critical textual analysis can occur. Hence, this work creates a new pathway for subsequent textual discoveries buried within the confines of damaged materials.

Concepts: Codex, Manuscript, Ein Gedi, Torah, Israel, Scroll, Dead Sea, Dead Sea scrolls

91

Some of the coldest and driest permafrost soils on Earth are located in the high-elevation McMurdo Dry Valleys (MDVs) of Antarctica, but little is known about the permafrost microbial communities other than that microorganisms are present in these valleys. Here, we describe the microbiology and habitable conditions of highly unique dry and ice-cemented permafrost in University Valley, one of the coldest and driest regions in the MDVs (1700 m above sea level; mean temperature -23 °C; no degree days above freezing), where the ice in permafrost originates from vapour deposition rather than liquid water. We found that culturable and total microbial biomass in University Valley was extremely low, and microbial activity under ambient conditions was undetectable. Our results contrast with reports from the lower-elevation Dry Valleys and Arctic permafrost soils where active microbial populations are found, suggesting that the combination of severe cold, aridity, oligotrophy of University Valley permafrost soils severely limit microbial activity and survival.

Concepts: Microbiology, Dead Sea, Microorganism, Victoria Land, Antarctica, McMurdo Sound, McMurdo Dry Valleys, Water

58

The discovery on Mars of recurring slope lineae (RSL), thought to represent seasonal brines, has sparked interest in analogous environments on Earth. We report on new studies of Don Juan Pond (DJP), which exists at the upper limit of ephemeral water in the McMurdo Dry Valleys (MDV) of Antarctica, and is adjacent to several steep-sloped water tracks, the closest analog for RSL. The source of DJP has been interpreted to be deep groundwater. We present time-lapse data and meteorological measurements that confirm deliquescence within the DJP watershed and show that this, together with small amounts of meltwater, are capable of generating brines that control summertime water levels. Groundwater input was not observed. In addition to providing an analog for RSL formation, CaCl(2) brines and chloride deposits in basins may provide clues to the origin of ancient chloride deposits on Mars dating from the transition period from “warm/wet” to “cold/dry” climates.

Concepts: Lake Assal, Don Juan Pond, Water, McMurdo Sound, Lake, Antarctica, McMurdo Dry Valleys, Dead Sea

28

Trypanosoma evansi is the cause of surra in horses, camels and other domestic animals. Following the first outbreak of surra in horses and camels in Israel in 2006, a survey of the prevalence of the parasite in the Israeli horse population was conducted using serology, PCR followed by the reverse dot blot (RDB) technique and blood smear microscopy. In total, 614 horses from 7 regions were sampled. The CATT/T. evansi kit was used for serology for all the horses. Horses from the Arava and Dead Sea region, where the first outbreak occurred, were sampled again one year later and both samples were subjected to serology and the RDB technique. The country wide seroprevalence was 4.6% (28/614). The seroprevalence in the Arava and Dead Sea region was 6.5% (9/139) in the first sampling compared with 4.1% (5/122) in the second, whereas the prevalence of RDB-positivity was 18.7% (26/139) in the first sampling and only 0.8% (1/122) in the second. All horses were asymptomatic except for one horse from the Arava and Dead Sea region that demonstrated clinical signs of surra combined with positive serology and RDB. The results of this study indicated that surra is prevalent in most regions of the country and thus should be considered an important differential diagnosis in horses and other domestic animals in Israel with chronic weight loss, edema or neurological signs.

Concepts: Sea, West Bank, Medical diagnosis, Trypanosoma evansi, Epidemiology, Jordan, Israel, Dead Sea

27

The light-driven outward proton transporter assists energy production via an ATP synthase system best exemplified by the bacteriorhodopsin (BR) from Halobacterium salinarum, HsBR. As the only archaea able to survive in the resource-limited ecosystem of the Dead Sea, Haloarcula marismortui has been reported to have a unique dual-BR system, consisting of HmBRI and HmBRII, instead of only a single BR in a cell (solo-BR). The contribution of this dual-BR system to survival was investigated. First, native H. marismortui and H. salinarum cells were tested in water that had been adjusted to mimic the conditions of Dead Sea water. These archaea were shown to accumulate protons and reduce pH in their periplasmic regions, which disabled further proton transportation functionality in H. salinarum but not in H. marismortui. Then, pH-dependent photocurrent measurements using purified BR proteins demonstrated that HsBR and HmBRI were functional at pH > 5.0 and that HmBRII was functional at pH > 4.0. Our results indicate that the dual-HmBR system is composed of two BRs with different optimal functional pH ranges and together they maintain light-driven proton transport activity under pH > 4.0, which might contribute the survival of H. marismortui under the acidic pH of the Dead Sea.

Concepts: Sodium chloride, Archaea, Sea, Halobacterium, Acid, Seawater, PH, Dead Sea

10

Sea spray is one of the largest natural aerosol sources and plays an important role in the Earth’s radiative budget. These particles are inherently hygroscopic, that is, they take-up moisture from the air, which affects the extent to which they interact with solar radiation. We demonstrate that the hygroscopic growth of inorganic sea salt is 8-15% lower than pure sodium chloride, most likely due to the presence of hydrates. We observe an increase in hygroscopic growth with decreasing particle size (for particle diameters <150 nm) that is independent of the particle generation method. We vary the hygroscopic growth of the inorganic sea salt within a general circulation model and show that a reduced hygroscopicity leads to a reduction in aerosol-radiation interactions, manifested by a latitudinal-dependent reduction of the aerosol optical depth by up to 15%, while cloud-related parameters are unaffected. We propose that a value of κs=1.1 (at RH=90%) is used to represent the hygroscopicity of inorganic sea salt particles in numerical models.

Concepts: Dead Sea, Redox, Chloride, Standard Model, Salt, Sodium hydroxide, Sodium, Sodium chloride

9

Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low density of cells most of which are Archaea. We discovered several underwater fresh to brackish water springs in the Dead Sea harboring dense microbial communities. We provide the first characterization of these communities, discuss their possible origin, hydrochemical environment, energetic resources and the putative biogeochemical pathways they are mediating. Pyrosequencing of the 16S rRNA gene and community fingerprinting methods showed that the spring community originates from the Dead Sea sediments and not from the aquifer. Furthermore, it suggested that there is a dense Archaeal community in the shoreline pore water of the lake. Sequences of bacterial sulfate reducers, nitrifiers iron oxidizers and iron reducers were identified as well. Analysis of white and green biofilms suggested that sulfide oxidation through chemolitotrophy and phototrophy is highly significant. Hyperspectral analysis showed a tight association between abundant green sulfur bacteria and cyanobacteria in the green biofilms. Together, our findings show that the Dead Sea floor harbors diverse microbial communities, part of which is not known from other hypersaline environments. Analysis of the water’s chemistry shows evidence of microbial activity along the path and suggests that the springs supply nitrogen, phosphorus and organic matter to the microbial communities in the Dead Sea. The underwater springs are a newly recognized water source for the Dead Sea. Their input of microorganisms and nutrients needs to be considered in the assessment of possible impact of dilution events of the lake surface waters, such as those that will occur in the future due to the intended establishment of the Red Sea-Dead Sea water conduit.

Concepts: 16S ribosomal RNA, Dead Sea, Seawater, Photosynthesis, Microbiology, Archaea, Water, Bacteria

6

Temporal distribution of earthquakes is key to seismic hazard assessment. However, for most fault systems shortness of large earthquake catalogues makes this assessment difficult. Its unique long earthquake record makes the Dead Sea fault (DSF) exceptional to test earthquake behaviour models. A paleoseismological trench along the southern section of the DSF, revealed twelve surface-rupturing earthquakes during the last 8000 years, of which many correlate with past earthquakes reported in historical chronicles. These data allowed us building a rupture scenario for this area, which includes timing and rupture length for all significant earthquakes during the last two millenaries. Extending this rupture scenario to the entire DSF south of Lebanon, we were able to confirm the temporal-clustering hypothesis. Using rupture length and scaling laws, we have estimated average co-seismic slip for each past earthquake. The cumulated slip was then balanced with long-term tectonic loading to estimate the slip deficit for this part of DSF over the last 1600 years. The seismic-slip budget shows that the slip deficit is similarly high along the fault with a minimum of 2 meters, which suggests that an earthquake cluster might happen over the entire region in the near future.

Concepts: Seismology, Israel, Dead Sea Transform, Jordan Rift Valley, Sea, Earth, Dead Sea, Earthquake

3

The overall aim of the this study, which was conducted within the framework of the multilateral IWRM project SUMAR, was to expand the scientific basement to quantify surface- and groundwater fluxes towards the hypersaline Dead Sea. The flux significance for the arid vicinity around the Dead Sea is decisive not only for a sustainable management in terms of water availability for future generations but also for the resilience of the unique ecosystems along its coast. Coping with different challenges interdisciplinary methods like (i) hydrogeochemical fingerprinting, (ii) satellite and airborne-based thermal remote sensing, (iii) direct measurement with gauging station in ephemeral wadis and a first multilateral gauging station at the river Jordan, (iv) hydro-bio-geochemical approach at submarine and shore springs along the Dead Sea and (v) hydro(geo)logical modelling contributed to the overall aim. As primary results, we deduce that the following: The results of this work show a promising enhancement of describing and modelling the Dead Sea basin as a whole.

Concepts: Jordan Rift Valley, West Bank, Water, Geography of Israel, Israel, Jordan River, Jordan, Dead Sea

2

In the age-old debate between technological optimists and pessimists, desalination has been hailed as a “game changer” that can fundamentally alter the dynamics of water management under conditions of scarcity. While water from desalination facilities can reduce uncertainties in municipal supply, they are unlikely to replace the missing flow required to rehabilitate rivers and streams. The Jordan River is an iconic, but highly degraded water body whose restoration has been the subject of extensive research as well as numerous proposals and strategies. A review of the present state of the River and prospects for successful rehabilitation efforts reveals that neither the increase in the riparian population nor the reduced water supply due to climate change in the Jordan basin has been considered sufficiently in restoration strategies. Demographic pressures produce acute water shortages which make the provision of future environmental flows highly unlikely. While much can and should be done to improve its environmental condition, the Jordan River offers a cautionary tale for water scarce regions about the challenge of stream restoration initiatives in the face of accelerated population growth, notwithstanding the potential benefits of desalination as a source of drinking water.

Concepts: Jordan River, Jordan, Rivers, River, Dead Sea, Water, Water supply, Stream