scholarly journals Controls on the Radiocarbon Reservoir Ages in the Modern Dead Sea Drainage System and in the Last Glacial Lake Lisan

Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 969-982 ◽  
Author(s):  
Reuven Belmaker ◽  
Mordechai Stein ◽  
Yoseph Yechieli ◽  
Boaz Lazar
Keyword(s):  
Mass Balance ◽  
Sea Water ◽  
Dissolved Inorganic Carbon ◽  
Dead Sea ◽  
Glacial Lake ◽  
Chemical Compositions ◽  
Exchange Reactions ◽  
Last Glacial ◽  
The Dead ◽  
The Last Glacial

Carbon isotopic and chemical compositions of freshwaters feeding the Dead Sea and the Sea of Galilee (i.e. perennial streams and floods along their stream profiles) were used to constrain the factors that dictate the reservoir ages (RA) of these lakes and the last glacial Lake Lisan. Runoff waters are characterized by high Ca2+, Mg2+, alkalinity, and radiocarbon contents (67–108 pMC), suggesting a major role for 14C atmospheric exchange reactions (carbonate rock dissolution alone will result in lower pMC values). These exchange processes were corroborated by dissolved inorganic carbon (DIC) and δ13C trends throughout the flood profile. During the evolution from rain to incipient runoff, the 14CDIC of the water increases and is accompanied by a DIC increase and δ13CDIC decrease, suggesting an addition of soil CO2, which is characterized by light δ13C and high 14C content. When incipient runoffs evolve to floods, the opposite trends are observed.It appears that the Sea of Galilee, the Dead Sea, and its last glacial precursor, Lake Lisan, maintained uniform but specific RAs of 0.8 ± 0.1, 2.3 ± 0.1, and 1.6 ± 0.3 kyr, respectively. However, applying the 14C contents of modern Dead Sea water sources to the water mass balance of Lake Lisan reveals that the RA of Lake Lisan is higher than that predicted by the mass balance. This discrepancy may reflect enhanced dissolution of carbonatic dust, changes in the amount of 14C exchanged in Judean Desert floods, or variations in the contribution of brine and saline springs. Furthermore, the small fluctuations in the Lisan RA (1.6 ± 0.3 kyr) may reflect small, short-term changes in the relative contributions of these sources.

Changes in biogeochemistry recorded in the Lisan formation and the Dead Sea Basin

2020 ◽  
Author(s):  
Alexandra Turchyn ◽  
Harold Bradbury ◽  
Adi Torfstein
Keyword(s):  
Climate Change ◽  
Isotopic Composition ◽  
Hydrological Cycle ◽  
Dead Sea ◽  
Glacial Cycle ◽  
Last Glacial ◽  
The Dead ◽  
Lisan Formation ◽  
The Last Glacial ◽  
Arava Valley

<p>Terrestrial climate archives provide a rich array of information on regional climate dynamics that often can link to global climate change.  A range of new metal and coupled isotope proxies is helping to unlock the most information from terrestrial archives and this paleoclimate information. The Jordon-Arava valley, tectonically active since the early Neogene, is one of the world’s largest pull-apart basins.  Throughout the Pleistocene to the Holocene, the valley contained a series of lacustrine water bodies.  As the valley is located on the boundary between the African-Arabian deserts and the Mediterranean regional climatic zone, studies of past conditions in these lacustrine bodies allows the reconstruction of changes in the regional hydrological cycle.  Lacustrine sediments, such as those found in the Jordon-Arava valley, record paleoclimatic information similar to that found within marine sedimentary archives and often at much higher resolution, from millennial to even annual timescales. The Lisan Formation is a 40-80m thick Pleistocene marl, which was deposited in Lake Lisan, which existed over the last glacial cycle in the Jordan-Arava Valley. The Lisan Formation contains a significant quantity of annually-precipitated primary aragonite, which has not recrystallised to calcite, allowing for direct U-Th dating, which has led to an exceptional age model for the Lisan Formation.</p><p>Here we discuss the measurement of the sulfur and oxygen isotopic composition of gypsum in the Lisan formation, as well as the generation of sulfur nodules within the formation that are not found in the sediment cores of the Dead Sea. We use this data to explore how sediment diagenesis, relating to changes in biogeochemistry, changes as a function of climate change over the last glacial cycle. We then present the calcium isotopic composition of the gypsum and interbedded aragonite, and show how the aragonite calcium isotopic composition covaries with lake level, and thus offers profound insight into the regional hydrological cycle in the Jordon-Arava Valley.</p>

The diatom flora of Lake Lisan (Israel): a preliminary investigation

2020 ◽  
Author(s):  
Hannah Hartung ◽  
Jane M. Reed ◽  
Thomas Litt
Keyword(s):  
Lake Level ◽  
Eastern Mediterranean ◽  
Sediment Cores ◽  
Dead Sea ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Diatom Flora ◽  
Last Glacial ◽  
The Dead ◽  
The Last Glacial

<p>The Eastern Mediterranean, and the southern Levant in particular, is a key region for palaeoclimatological and palaeoenvironmental research due to its highly complex topography and climatic variability. Our understanding of environmental variability and its possible drivers, and the interaction with migration processes of modern <em>Homo sapiens</em> from a source area in Africa to Europe, is still limited. This is partly because continuous sediment records of sufficient age are rare across the Mediterranean Basin. The deposits of the Dead Sea represent an ideal archive to investigate palaeoenvironmental conditions during human migration phases in the Last Glacial period (MIS 4-2). </p><p>Diatoms (single-celled siliceous algae, Bacillariophyceae) have well-recognised potential to generate high-quality palaeolimnological data, especially in closed-basin saline lakes, but they remain one of the least-exploited proxies in Eastern Mediterranean palaeoclimate research. Here, we present preliminary results of a low-resolution diatom study derived from analysis of sediment deposits of Lake Lisan, the last glacial precursor of the Dead Sea. Sediment cores were recovered during an ICDP campaign in 2010/2011 from the centre of the modern Dead Sea. 18 sediment samples were analysed to investigate (a) the preservation of diatom valves in various evaporitic deposits (b) possible shifts in diatom species composition of Lake Lisan during the Last Glacial period, and (c) if diatoms can be used as proxy indicator for lake-level and, thus, palaeoclimate reconstruction. We focus on a prominent lake-level high stand of Lake Lisan at around 28-22 ka BP, which resulted in the merging Lake Lisan and freshwater Lake Kinneret.</p><p>First results show that the diatom preservation is exceptionally good in evaporitic deposits of the sediment cores from Lake Lisan, which is contradictory to the available literature. In contrast to Holocene deposits from the Dead Sea, diatoms are abundant in all analysed samples from laminated deposits from Lake Lisan: the diatom flora is dominated by halophilous benthic diatoms, such as <em>Amphora</em> spp., <em>Halamphora</em> spp. and <em>Nitzschia</em> spp. In phases of lake-level high stands of Lake Lisan, the diatom flora shifts towards a more plankton-dominated freshwater flora containing <em>Aulacoseira</em> spp. and taxa from the <em>Cyclotella-ocellata-</em>species complex.</p>

scholarly journals Carbon burial in deep-sea sediment and implications for oceanic inventories of carbon and alkalinity over the last glacial cycle

2018 ◽  
Vol 14 (11) ◽  
pp. 1819-1850 ◽  
Author(s):  
Olivier Cartapanis ◽  
Eric D. Galbraith ◽  
Daniele Bianchi ◽  
Samuel L. Jaccard
Keyword(s):  
Marine Sediments ◽  
Active Carbon ◽  
Deep Sea ◽  
Dissolved Inorganic Carbon ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Carbon Burial ◽  
Order Constraint ◽  
The Last Glacial ◽  
Carbon Inventory

Abstract. Although it has long been assumed that the glacial–interglacial cycles of atmospheric CO2 occurred due to increased storage of CO2 in the ocean, with no change in the size of the “active” carbon inventory, there are signs that the geological CO2 supply rate to the active pool varied significantly. The resulting changes of the carbon inventory cannot be assessed without constraining the rate of carbon removal from the system, which largely occurs in marine sediments. The oceanic supply of alkalinity is also removed by the burial of calcium carbonate in marine sediments, which plays a major role in air–sea partitioning of the active carbon inventory. Here, we present the first global reconstruction of carbon and alkalinity burial in deep-sea sediments over the last glacial cycle. Although subject to large uncertainties, the reconstruction provides a first-order constraint on the effects of changes in deep-sea burial fluxes on global carbon and alkalinity inventories over the last glacial cycle. The results suggest that reduced burial of carbonate in the Atlantic Ocean was not entirely compensated by the increased burial in the Pacific basin during the last glacial period, which would have caused a gradual buildup of alkalinity in the ocean. We also consider the magnitude of possible changes in the larger but poorly constrained rates of burial on continental shelves, and show that these could have been significantly larger than the deep-sea burial changes. The burial-driven inventory variations are sufficiently large to have significantly altered the δ13C of the ocean–atmosphere carbon and changed the average dissolved inorganic carbon (DIC) and alkalinity concentrations of the ocean by more than 100 µM, confirming that carbon burial fluxes were a dynamic, interactive component of the glacial cycles that significantly modified the size of the active carbon pool. Our results also suggest that geological sources and sinks were significantly unbalanced during the late Holocene, leading to a slow net removal flux on the order of 0.1 PgC yr−1 prior to the rapid input of carbon during the industrial period.

Exploring the complex uncertainties in coupled climate-ice simulations of the Last Glacial Maximum

2021 ◽  
Author(s):  
Lauren Gregoire ◽  
Niall Gandy ◽  
Lachlan Astfalck ◽  
Robin Smith ◽  
Ruza Ivanovic ◽  
...  
Keyword(s):  
Mass Balance ◽  
Last Glacial Maximum ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Sea Surface ◽  
Surface Mass ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

<p>Simulating the co-evolution of climate and ice-sheets during the Quaternary is key to understanding some of the major abrupt changes in climate, ice and sea level. Indeed, events such as the Meltwater pulse 1a rapid sea level rise and Heinrich, Dansgaard–Oeschger and the 8.2 kyr climatic events all involve the interplay between ice sheets, the atmosphere and the ocean. Unfortunately, it is challenging to simulate the coupled Climate-Ice sheet system because small biases, errors or uncertainties in parts of the models are strongly amplified by the powerful interactions between the atmosphere and ice (e.g. ice-albedo and height-mass balance feedbacks). This leads to inaccurate or even unrealistic simulations of ice sheet extent and surface climate. To overcome this issue we need some methods to effectively explore the uncertainty in the complex Climate-Ice sheet system and reduce model biases. Here we present our approach to produce ensemble of coupled Climate-Ice sheet simulations of the Last Glacial maximum that explore the uncertainties in climate and ice sheet processes.</p><p>We use the FAMOUS-ICE earth system model, which comprises a coarse-resolution and fast general circulation model coupled to the Glimmer-CISM ice sheet model. We prescribe sea surface temperature and sea ice concentrations in order to control and reduce biases in polar climate, which strongly affect the surface mass balance and simulated extent of the northern hemisphere ice sheets. We develop and apply a method to reconstruct and sample a range of realistic sea surface temperature and sea-ice concentration spatio-temporal field. These are created by merging information from PMIP3/4 climate simulations and proxy-data for sea surface temperatures at the Last Glacial Maximum with Bayes linear analysis. We then use these to generate ensembles of FAMOUS-ice simulations of the Last Glacial maximum following the PMIP4 protocol, with the Greenland and North American ice sheets interactively simulated. In addition to exploring a range of sea surface conditions, we also vary key parameters that control the surface mass balance and flow of ice sheets. We thus produce ensembles of simulations that will later be used to emulate ice sheet surface mass balance.  </p>

Dead Sea Water Levels Analysis Using Artificial Neural Networks and Firefly Algorithm

2022 ◽  
pp. 1118-1129
Author(s):  
Nawaf N. Hamadneh
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Water Level ◽  
Firefly Algorithm ◽  
Sea Water ◽  
Dead Sea ◽  
Water Levels ◽  
Artificial Neural ◽  
The Dead ◽  
Predicted Values

In this study, the performance of adaptive multilayer perceptron neural network (MLPNN) for predicting the Dead Sea water level is discussed. Firefly Algorithm (FFA), as an optimization algorithm is used for training the neural networks. To propose the MLPNN-FFA model, Dead Sea water levels over the period 1810–2005 are applied to train MLPNN. Statistical tests evaluate the accuracy of the hybrid MLPNN-FFA model. The predicted values of the proposed model were compared with the results obtained by another method. The results reveal that the artificial neural network (ANN) models exhibit high accuracy and reliability for the prediction of the Dead Sea water levels. The results also reveal that the Dead Sea water level would be around -450 until 2050.

RADIOCARBON RESERVOIR AGES IN THE HOLOCENE DEAD SEA

Radiocarbon ◽  
2020 ◽  
Vol 62 (5) ◽  
pp. 1453-1473
Author(s):  
Nurit Weber ◽  
Boaz Lazar ◽  
Ofra Stern ◽  
George Burr ◽  
Ittai Gavrieli ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Dead Sea ◽  
Climate Conditions ◽  
The Holocene ◽  
Radiocarbon Age ◽  
The Past ◽  
Organic Debris ◽  
The Dead ◽  
The Difference ◽  
Continuous Deposition

ABSTRACTThe sources and fate of radiocarbon (14C) in the Dead Sea hypersaline solution are evaluated with 14C measurements in organic debris and primary aragonite collected from exposures of the Holocene Ze’elim Formation. The reservoir age (RA) is defined as the difference between the radiocarbon age of the aragonite at time of its precipitation (representing lakeʼs dissolved inorganic carbon [DIC]) and the age of contemporaneous organic debris (representing atmospheric radiocarbon). Evaluation of the data for the past 6000 yr from Dead Sea sediments reveal that the lakeʼs RA decreased from 2890 yr at 6 cal kyr BP to 2300 yr at present. The RA lies at ~2400 yr during the past 3000 yr, when the lake was characterized by continuous deposition of primary aragonite, which implies a continuous supply of freshwater-bicarbonate into the lake. This process reflects the overall stability of the hydrological-climate conditions in the lakeʼs watershed during the late Holocene where bicarbonate originated from dissolution of the surface cover in the watershed that was transported to the Dead Sea by the freshwater runoff. An excellent correlation (R2=0.98) exists between aragonite ages and contemporaneous organic debris, allowing the estimation of ages of various primary deposits where organic debris are not available.

A 45 kyr laminae record from the Dead Sea: Implications for basin erosion and floods recurrence

2020 ◽  
Author(s):  
Nicolas Waldmann ◽  
Yin Lu ◽  
Revital Bookman ◽  
Shmulik Marco
Keyword(s):  
High Frequency ◽  
Lake Level ◽  
Dead Sea ◽  
Last Deglaciation ◽  
The Holocene ◽  
Lamina Thickness ◽  
The Last Deglaciation ◽  
The Dead ◽  
Basin Erosion ◽  
The Last Glacial

<p>Recording and analyzing how climate change impacts flood recurrence, basin erosion, and sedimentation can improve our understanding of these systems. The aragonite-detritus laminae couplets comprising the lacustrine formations that were deposited in the Dead Sea Basin are considered as faithful monitors of the freshwater supply to the lakes. We count a total of ~5600 laminae couplets deposited in the last 45 kyr (MIS3-MIS1) at the Dead Sea depocenter, which encompass the upper 141.6 m of the ICDP Core 5017-1. The present study shows that aragonite and detritus laminae are thinner and occur at high frequency during MIS 3-2, while they are much thicker and less frequent during MIS 1. By analyzing multiple climate-connected factors, we propose that significant lake-level drops, enhanced dust input, and low vegetative cover in the drainage basin during the last deglaciation (22-11.6 ka) have considerably increased erodible materials in the Dead Sea watershed. We find a decoupling existed between the significant lake-level drop/lake size reduction and lamina thickness change during the last deglaciation. We argue that during the last glacial and the Holocene, the variation of lamina thickness at the multiple-millennium scale was not controlled directly by the lake-level/size change. We interpret this decoupling implying the transport capacity of flash-floods is low and might be saturated by the oversupply of erodible materials, and indicating a transport-limited regime during the time period. We suggest that the observed thickness and frequency distribution of aragonite-detritus laminae points to the high frequency of small-magnitude floods during the last glacial period, in contrast to low frequency, but large-magnitude floods during the Holocene.</p>

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