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  • 1
    Electronic Resource
    Electronic Resource
    Temporal variations in dissolved selenium in Lake Kinneret (Israel) (1999)
    Springer
    Aquatic sciences 61 (1999), S. 215-233 
    Details
    ISSN: 1420-9055
    Keywords: Key words: Selenium, lakes [IB1].
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract: Selenium is an essential micronutrient for the growth of the dinoflagellate Peridinium gatunense that dominates the spring algal bloom in Lake Kinneret (LK). The relationship between the levels of dissolved selenium species and the occurance of algal blooms in this lake was studied. During algal blooms of P. gatunense in spring and of the blue-green Aphanizomenon ovalisporum in fall (in 1994) the concentration of epilimnetic dissolved organic Se (Seorg) increased whereas that of selenite (SeIV) decreased, to levels below the limit of detection: 5ng/l. The disappearance of SeIV during these blooms is attributed to algal uptake and it is suggested that the growth of both algae may have depended on Seorg regeneration. A budget performed for selenate (SeVI) suggests that this species is also consumed by algae but to a lesser extent than SeIV (in 1994 ∼ 40 % of the epilimnetic load). During the stratification period the hypolimnion of Lake Kinneret becomes anoxic, with high levels of dissolved sulfide. The affects of this environment on the distribution of Se oxy-anions, selenite (SeIV) and selenate (SeVI), were also studied. At the onset of thermal stratification (March) about 35 % of the lake inventory of both Se oxidized species are entrapped in the hypolimnion. During stages of oxygen depletion and H2S accumulation, SeIV is completely and SeVI partially removed from this layer. The removal is attributed to reduction followed by formation of particulate reduced products, such as elemental selenium Se(o). The ratio between SeVI to total dissolved selenium (SeT) in water sources to the lake is ∼ 0.84, about twice the corresponding ratio in the lake (∼ 0.44, during holomixis). In the lake about 75 % of annual SeVI inflow from external sources undergoes reduction to selenide (Se-II) and Se(o) through epilimnetic algal assimilation and hypolimnetic anoxic reduction, respectively. It is suggested that the latter oxidation of the dissolved organic selenide released from biogenic particles and of Se(o) only to the tetravalent species is the cause for the lower ratio of SeVI/SeT in the lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000270050063
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Lake Kinneret dissolved oxygen regime reflects long term changes in ecosystem functioning (1998)
    Springer
    Biogeochemistry 42 (1998), S. 253-283 
    Details
    ISSN: 1573-515X
    Keywords: dissolved oxygen concentration ; yearly oxygen budgets ; hypolimnetic respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Lake Kinneret (Israel) has undergone several prominent chemical and biological changes since 1970. Between 1970 and 1991 significant, long-term gradual increase were recorded in epilimnetic dissolved oxygen (DO) concentrations (about 20%), and in pH levels (0.2 units). Concomitantly there was a significant increase in hypolimnetic H2S concentrations (about 75%) and a long-term gradual drop in zooplankton biomass (50%). Since 1994 these trends were reversed and the levels of the three chemical parameters have returned to those found in the 1970's and that of zooplankton to mid 1980's levels. The present study is an attempt to relate some of these long term changes by means of yearly oxygen budgets, based on fluxes of oxygen producing and consuming processes. This analysis raises the possibility that part of the long-term increase in epilimnetic DO and pH between 1970 to 1990 may be attributed to reduced inputs of organic matter from alochthonous sources and possibly to enhanced burial of organic matter in the bed sediments. However, the major cause for the observed increase in epilimnetic DO and pH is increased sedimentation of organic matter to the hypolimnion during stratification. As indicated by the amount of H2S formed in the hypolimnion during stratification added to the amount of oxygen entrapped in this layer at the onset of thermal stratification, between 1970 to 1991 the sedimentation flux of organic matter increased by approximately 40%. It is estimated that during these two decades hypolimnetic respiration increased from ca. 8% of the annual amount of oxygen evolved due to photosynthesis during the early 1970's to ca. 12.5% during the 1980's. The shift in the layer of oxidative processes is suggested to be the result of a multi-annual decline in zooplankton grazing pressure, which led to increased sedimentation of organic matter. The reversed trends for DO, pH and H2S since 1994 may have partially been due to the increase in zooplankton activity and partially due to changes in phytoplankton community structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005921029867
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  • 3
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    Radionuclides and recent sedimentation and mixing rates in Northern Gulf of Eilat/Aqaba, Red Sea (2014)
    In:  EPIC3Journal of Marine Systems, 139, pp. 1-8, ISSN: 09247963
    Details
    Publication Date: 2018-05-24
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 4
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    Radionuclides activity concentrations of sediment core A2
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: A2; Caesium-137; Caesium-137, decision threshold; Caesium-137, standard deviation; Calculated; Core_A2; Density, dry bulk; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Gamma-ray spectrometry; GC; Gravity corer; Gulf of Aqaba, northern Red Sea; Inductively coupled plasma - mass spectrometry (ICP-MS); Lead-210 excess; Lead-210 excess, standard deviation; Potassium-40; Potassium-40, standard deviation; Radium-226, standard deviation; Radium-226 activity per mass; Radium-228, standard deviation; Radium-228 activity per mass; Thorium-228; Thorium-228, standard deviation; Thorium-232 activity per mass
    Type: Dataset
    Format: text/tab-separated-values, 337 data points
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  • 5
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    Radionuclides activity concentrations of sediment core B
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: B; Caesium-137; Caesium-137, decision threshold; Caesium-137, standard deviation; Calculated; Core_B; Density, dry bulk; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Gamma-ray spectrometry; GC; Gravity corer; Gulf of Aqaba, northern Red Sea; Inductively coupled plasma - mass spectrometry (ICP-MS); Lead-210 excess; Lead-210 excess, standard deviation; Potassium-40; Potassium-40, standard deviation; Radium-226, standard deviation; Radium-226 activity per mass; Radium-228, standard deviation; Radium-228 activity per mass; Thorium-228; Thorium-228, standard deviation; Thorium-232 activity per mass
    Type: Dataset
    Format: text/tab-separated-values, 253 data points
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  • 6
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    Radionuclides activity concentrations of sediment core F (2015)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: Caesium-137; Caesium-137, decision threshold; Caesium-137, standard deviation; Calculated; Core_F; Density, dry bulk; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; F; Gamma-ray spectrometry; GC; Gravity corer; Gulf of Aqaba, northern Red Sea; Inductively coupled plasma - mass spectrometry (ICP-MS); Lead-210 excess; Lead-210 excess, standard deviation; Potassium-40; Potassium-40, standard deviation; Radium-226, standard deviation; Radium-226 activity per mass; Radium-228, standard deviation; Radium-228 activity per mass; Thorium-228; Thorium-228, standard deviation; Thorium-232 activity per mass
    Type: Dataset
    Format: text/tab-separated-values, 251 data points
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  • 7
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    Radionuclides activity concentrations of sediment core HHN2C (2015)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: Caesium-137; Caesium-137, decision threshold; Caesium-137, standard deviation; Calculated; Density, dry bulk; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Gamma-ray spectrometry; GC; Gravity corer; Gulf of Aqaba, northern Red Sea; HHN2C; Inductively coupled plasma - mass spectrometry (ICP-MS); Lead-210 excess; Lead-210 excess, standard deviation; Potassium-40; Potassium-40, standard deviation; Radium-226, standard deviation; Radium-226 activity per mass; Radium-228, standard deviation; Radium-228 activity per mass; Thorium-228; Thorium-228, standard deviation; Thorium-232 activity per mass
    Type: Dataset
    Format: text/tab-separated-values, 250 data points
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  • 8
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    Radionuclides activity concentrations of sediment core HHN3 (2015)
    PANGAEA
    Details
    Publication Date: 2023-06-27
    Keywords: Caesium-137; Caesium-137, decision threshold; Caesium-137, standard deviation; Calculated; Density, dry bulk; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Gamma-ray spectrometry; GC; Gravity corer; Gulf of Aqaba, northern Red Sea; HHN3; Lead-210 excess; Lead-210 excess, standard deviation; Potassium-40; Potassium-40, standard deviation; Radium-226, standard deviation; Radium-226 activity per mass; Radium-228, standard deviation; Radium-228 activity per mass; Thorium-228; Thorium-228, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 290 data points
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  • 9
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    Activity concentrations of radionuclides in 5 short cores taken in 2007-2008 measured by ICP-MS and HPGe gamma spectrometry
    PANGAEA
    In:  Supplement to: Pittauerova, Daniela; Kirchner, Gerald; Garbe-Schönberg, Dieter; Herut, Barak; Nishri, Ami; Fischer, Helmut W (2014): Radionuclides and recent sedimentation and mixing rates in Northern Gulf of Eilat/Aqaba, Red Sea. Journal of Marine Systems, 139, 1-8, https://doi.org/10.1016/j.jmarsys.2014.04.017
    Details
    Publication Date: 2023-06-08
    Description: Natural radionuclides and man-made 137Cs were analyzed in five short sediment cores taken in northern part of the Gulf of Eilat (Gulf of Aqaba) in order to provide information on sedimentation and mixing rates and sediment sources. The maximum estimates of sedimentation rates based on excess 210Pb were found to vary between 0.105 ± 0.020 and 0.35 ± 0.23 cm · year**-1. Even the lowest estimates are significantly higher than those expected from dust deposition, suggesting other sources and processes being responsible for most of the allochthonous material accumulation, including periodical floods following heavy rain events, internal erosion or triggers, like earthquakes. In 137Cs depth profiles no 1963 related nuclear weapon test maxima were found; instead, the activities decrease monotonically, suggesting that a major process leading to radionuclides' depth distribution might be mixing. The mixing rates calculated from 137Cs, excess 210Pb and excess 228Th reach values up to 2.18 ± 0.69 cm**2 · year**-1.
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 10
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    Geochemistry of sediment core Kinneret_AA3 (2013)
    PANGAEA
    In:  Supplement to: Quintana Krupinski, Nadine B; Marlon, Jennifer R; Nishri, Ami; Street, Joseph H; Paytan, Adina (2013): Climatic and human controls on the late Holocene fire history of northern Israel. Quaternary Research, 80(03), 396-405, https://doi.org/10.1016/j.yqres.2013.06.012
    Details
    Publication Date: 2023-12-05
    Description: Long-term fire histories provide insight into the effects of climate, ecology and humans on fire activity; they can be generated using accumulation rates of charcoal and soot black carbon in lacustrine sediments. This study uses both charcoal and black carbon, and other paleoclimate indicators from Lake Kinneret (Sea of Galilee), Israel, to reconstruct late Holocene variations in biomass burning and aridity. We compare the fire history data with a regional biomass-burning reconstruction from 18 different charcoal records and with pollen, climate, and population data to decipher the relative impacts of regional climate, vegetation changes, and human activity on fire. We show a long-term decline in fire activity over the past 3070 years, from high biomass burning ~3070-1750 cal yr BP to significantly lower levels after ~1750 cal yr BP. Human modification of the landscape (e.g., forest clearing, agriculture, settlement expansion and early industry) in periods of low to moderate precipitation appears to have been the greatest cause of high biomass burning during the late Holocene in southern Levant, while wetter climate apparently reduced fire activity during periods of both low and high human activity.
    Keywords: Accumulation rate, black carbon mass; Accumulation rate, charcoal; AGE; Calcium carbonate; Carbon, organic, total; Carbon/Nitrogen ratio; DEPTH, sediment/rock; GC; Gravity corer; Kinneret_AA3; Nitrogen, total; δ13C, black carbon; δ13C, carbonate; δ13C, organic carbon; δ15N; δ18O, carbonate
    Type: Dataset
    Format: text/tab-separated-values, 640 data points
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