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Publikationen

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Collecting cores in the field – the start of every publication!
Foto: Roland Zech

23 Publikationen filtern

Die Publikationen filtern

Hervorgehobene Autoren sind Angehörige der Universität Jena.

  1. Wetter or drier? Paleohydrological evidence from a 30-year resolution Holocene biomarker δD record from Moossee, Switzerland

    ErscheinungsjahrErschienen in:Quaternary science reviews : the international multidisciplinary research and review journal M. Prochnow, L. Danius, P. Strobel, F. Rey, L. Rittmeier, M. Zech, W. Tinner, R. Zech
    The hydrological cycle intensifies under global warming, causing humid areas to become wetter. However, rising temperatures also amplify seasonal ecosystem dryness, complicating the link between temperature and hydroclimate. Such divergent mechanisms challenge generalizations like 'warm and wet' in paleoclimatology on a global scale. On a regional scale, knowledge about evapotranspiration in response to past warming and cooling is still limited, but highly relevant to understand future hydroclimate. Here, we analyse the hydrogen isotope composition (δD) of aquatic and terrestrial biomarkers in varved sediments from Moossee, Switzerland, covering the past 7300 years at a temporal resolution of 30 years. Based on a dual biomarker approach, we reconstruct evapotranspiration at Moossee. Our data suggests that cool and wet conditions repeatedly favored rising lake levels and advancing glaciers in the Alps but lowered treelines, e.g. at the onset of the Neoglacial, dated to ∼5.5 cal ka BP. In contrast, warmer periods like the Mid Holocene or the Roman Warm Period were associated with dryness. Short-term hydrological fluctuations are partly explained by volcanic and solar forcings. Aside from an increased risk of strong convective rainfall and floods, paleohydrology provides robust evidence that an intensified hydrological cycle under global warming will substantially favor summer drought in Central Europe.
    Universitätsbibliographie Jena:
    fsu_mods_00027545Externer Link

  2. Pleistocene glacial geomorphology and chronology of the Nahuel Huapi-Limay and Traful catchments, northern Patagonia

    ErscheinungsjahrErschienen in:Geomorphology: an international journal on pure and applied geomorphology I. Mizerit, E. Morabito, F. Bechis, C. Terrizzano, A. Groos, G. Rugel, S. Merchel, R. Zech
    Universitätsbibliographie Jena:
    fsu_mods_00025293Externer Link

  3. A Late Glacial and Holocene sugar biomarker-based δ¹⁸O paleoclimate record from the Afro-alpine Central Lake, Bale Mountains, Ethiopia

    ErscheinungsjahrErschienen in:Global and planetary change: a daughter journal of palaeogeography, palaeoclimatology, palaeoecology S. Chernet, L. Bittner, G. Gil-Romera, B. Lemma, M. Bliedtner, R. Zech, B. Glaser, T. Bromm, S. Szidat, W. Zech, M. Zech
    The Eastern African region is an amalgamation of complex climate systems nestled in contrasting topographic barriers. Although rift basins are prime targets for studying the climate of the past, high-altitude climate archives in the context of paleoclimate research also offer invaluable insight and have yet to be fully explored. Here, we present a 17 kyr hydroclimate history of the Afro-alpine (4121 m a.s.l) Central Lake using a δ¹⁸O record established by analyzing hemicellulose-derived sugar biomarkers. The sugar biomarker patterns with a dominance of fucose indicate the predominance of autochthonous sedimentary organic matter. Therefore, the oxygen isotopic variability of the sugar biomarkers in general and of fucose in particular (δ¹⁸Ofucₒsₑ) reflects δ¹⁸Olₐkₑ wₐtₑr being controlled by climatic conditions, particularly lake water ¹⁸O enrichment by evaporation. Our δ¹⁸Ofucₒsₑ record from Central Lake indicates strong enrichment during the Late Glacial. Around 15 cal kyr BP, the onset of more humid climate marks the beginning of the African Humid Period (AHP) in the Bale Mountains. The AHP was interrupted by an arid period during the Late Glacial – Holocene transition roughly coinciding with the Younger Dryas (YD). After the YD, humid climatic conditions prevailed again until the Late Holocene when a gradual shift towards drier climate started. Our δ¹⁸Ofucₒsₑ record and interpretation agree well with the findings from adjacent low-altitude archives of Eastern Africa, the Indian Ocean paleoclimate records and the Asian Monsoon Domain, which suggests region-wide hydro-climatic teleconnections.
    Universitätsbibliographie Jena:
    fsu_mods_00026113Externer Link

  4. Comparing recent and buried Chernozems/Phaeozems in Central Germany: Soil transformation and human impact since 3.8 ka

    ErscheinungsjahrErschienen in:Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution H. von Suchodoletz, B. Schneider, A. Skokan, T. Nitz, B. Glaser, S. Polivka, K. Wiedner, F. Schlütz, T. Schunke, P. Kühn
    Universitätsbibliographie Jena:
    fsu_mods_00026016Externer Link

  5. Late Glacial summer paleohydrology across Central Europe

    ErscheinungsjahrErschienen in:Scientific Reports M. Prochnow, J. Hepp, P. Strobel, R. Zech, S. Acharya, S. Szidat, D. Rius, L. Millet, B. Glaser, M. Zech
    It is generally accepted that a weakening of the North Atlantic thermohaline circulation caused the Younger Dryas cooling. Although the role of seasonality was emphasized previously, this aspect is rarely considered yet, and it remains elusive how this impacted hydroclimate during winters and summers across Central Europe. Here, we coupled biomarker-based δ¹⁸O and δ²H from Bergsee in southern Germany to reconstruct deuterium excess as a proxy for evaporation history from the Bølling-Allerød to the Preboreal. We compared this dataset with other biomarker isotope records in Central Europe. They are all lacking a strong isotopic depletion during the Younger Dryas, which is best explained by the summer sensitivity of the biomarker proxies: As Younger Dryas summers were relatively warm, there is an absence of the strong winter cooling signals recorded in annual water isotope records like Greenland or Lake Steißlingen. Lake evaporation at Bergsee together with other paleohydrological reconstructions draw a coherent picture of the Late Glacial hydroclimate, with strong evidence for warm and dry Younger Dryas summers. Rather than a southward shift of the Westerlies during winter, we suggest that a recently proposed feedback mechanism between North Atlantic sea ice extend, strong winter cooling and summer atmospheric blocking serves as a suitable explanation for summer dryness. Additional confidence to the robustness of these biomarker records is provided by the overall agreement of paleohydrological fluctuations during the Preboreal.
    Universitätsbibliographie Jena:
    fsu_mods_00018882Externer Link

  6. Paleoclimate, paleoenvironment, and human impact over the last 400 years based on lipid biomarkers from Lake Höglwörth, Germany

    ErscheinungsjahrErschienen in:Quaternary Science Advances S. Acharya, P. Strobel, M. Prochnow, S. Taut, M. Zech, A. Schwalb, R. Zech
    Lipid biomarkers are valuable proxies for reconstructing paleoclimate and paleoenvironmental changes as well as human impact. However, little attention has been paid on evaluating how the combination of biomarkers can be used to reconstruct various aspects of local paleoenvironmental conditions. This study presents a suite of lipid biomarker records from a sediment core from Lake Höglwörth, southern Germany, covering the past 400 years. Compound-specific hydrogen isotopic compositions (δD) of terrestrial n-alkanes (n-C₂₉₋ₐlkₐnₑ) and n-alkanoic acids (n-C₃₀₋ₐcid) indicate minor changes in isotopic composition of precipitation. The δD of n-C₂₂₋ₐcid is interpreted to record the isotopic composition of the lake water and evaporative enrichment, which drops after 1700 CE, coinciding with the construction of a mill and the related rerouting of a creek into Lake Höglwörth. The δD of n-C₂₅₋ₐlkₐnₑ is also enriched but decoupled from the reconstructed isotopic composition of precipitation and lake water. Therefore, we suggest that δD of n-C₂₅₋ₐlkₐnₑ reflects the leaf water isotopic composition of Sphagnum, which is present in the catchment and undergoes transpirative enrichment. Both short-chain compounds have become more enriched over the last century, maybe related to increasing temperature associated with anthropogenic climate warming. The faecal biomarkers record the changes in human population, partly related to the history of the local Monastery, the World Wars I and II as well as the intensive farming after the mid-20th century. Polycyclic aromatic hydrocarbons (PAHs) reveal a significant change in combustion activities associated with human activities such as the industrial revolution, biomass burning, and environmental cleanup as well as the implementation of emission standards. Our study demonstrates that the combination of plant wax compounds, faecal biomarkers, and PAHs from lacustrine sediment serves as a valuable tool to reconstruct and distinguish various aspects of paleoclimate and paleoenvironmental changes including human impacts.
    Universitätsbibliographie Jena:
    fsu_mods_00016348Externer Link

  7. Paleohydrology and human driven paleoproductivity during the Late Holocene from Schliersee, Bavaria

    ErscheinungsjahrErschienen in:Quaternary science reviews : the international multidisciplinary research and review journal M. Prochnow, K. Dulias, P. Strobel, M. Bliedtner, G. Daut, S. Szidat, G. Salazar, F. Lechleitner, S. Acharya, R. Martínez-Abarca, A. Schwarz, A. Schwalb, R. Zech
    Understanding Holocene hydroclimatic variability in the European Alps is challenging due to spatial and temporal disparities between the northern and southern Alps. In addition, interpreting lake sediment records in terms of paleohydrology is complicated by human presence during Roman and Medieval settlements, which increased soil erosion and lake eutrophication. Here, we present a ∼4440-year long sediment record from Schliersee, Bavaria, where we applied compound-specific δ²H on leaf waxes, geochemical and diatom analyses to reconstruct hydrology and lake productivity. The terrestrial δ²Hn₋C₃₁ records the isotopic composition of precipitation and is similar to leaf wax δ²H from Lake Ghirla, southern Alps, and δ¹⁸O from Spannagel cave in Austria. This provides evidence that, on millennial time scales, changes in moisture sources associated with shifts in the position of the Westerlies are one potential explanation regarding the isotope signals across the region. However, doubts remain whether the North Atlantic Oscillation as a winter signal can explain variations in summer-sensitive biomarker δ²H records. The aquatic δ²Hn₋C₂₅ records the isotopic composition of lake water and its isotopic offset to δ²Hn₋C₃₁ (Δₐq–tₑrr) is applied as a proxy for lake evaporation. We find increased evaporation during the Medieval Climate Anomaly in line with a drought reported from tree-ring studies, whereas lower evaporation prevailed during the Little Ice Age, likely due to solar forcing. Lake productivity was higher during the Roman period and Middle Ages, concomitant with land use resulting in higher nutrient inputs into the lake. The intensified use of industrial fertilizers and the drainage of untreated wastewater after the Second World War caused eutrophication during the 1950s. Despite its paleoclimatic significance, this study emphasizes that multi-proxy approaches combining assemblages of geochemical and biological proxies allow robust reconstructions of climate–landscape interactions and human impact.
    Universitätsbibliographie Jena:
    fsu_mods_00017932Externer Link

  8. North Atlantic Oscillation polarity during the past 3000 years derived from sediments of a large lowland lake, Schweriner See, in NE Germany

    ErscheinungsjahrErschienen in:Climate of the past: CP M. Adolph, S. Czerwiński, M. Dreßler, P. Strobel, M. Bliedtner, S. Lorenz, M. Debret, T. Haberzettl
    Based on a multi-dating and multi-proxy approach, we reconstruct Late Holocene environmental changes derived from sediments of Schweriner See, a large lowland lake in NE Germany, covering the past 3070⁺¹⁷⁰/₋₂₁₀ years cal BP. We infer variations in large-scale atmospheric circulation systems by combining in-lake productivity indicators obtained from traditional and high-resolution techniques (e.g. LOI₅₅₀, TOC, inc / coh), diatom assemblages, and compound-specific hydrogen isotopes (δ²HC₂₅). Before 105⁺⁹⁵/₋₇₅ cal BP (∼1850 CE), changes in productivity and the occurrence or disappearance of the diatom species Stephanocostis chantaicus reflect winter temperature variability, while variations in the compound-specific hydrogen isotopes suggest changes in the moisture source region. We observe distinct variations between (i) milder winter temperatures with a moisture source region in the southern-central North Atlantic and (ii) colder winter temperatures with a moisture source in the northern North Atlantic and/or Arctic regions. Such distinct variations in winter temperature and moisture source region are mainly modulated by the North Atlantic Oscillation (NAO). This affects, among others, westerly wind strength and pathways and, thereby, winter temperature and moisture source region for northern central Europe. Besides these long-term shifts in atmospheric conditions, short-term variations in titanium can be linked to lake-level variability, most likely influenced by changes in precipitation and/or evaporation, and after the 12th century to anthropogenic impacts. Since 105⁺⁹⁵/₋₇₅ cal BP (∼1850 CE), productivity has been driven predominantly by nutrient availability related to anthropogenic activities masking the hydroclimatic signal.
    Universitätsbibliographie Jena:
    fsu_mods_00017336Externer Link

  9. Holocene fire dynamics and their climatic controls on the southern Cape coast of South Africa - A 7.2 ka multi-proxy record from the peatland Vankervelsvlei

    ErscheinungsjahrErschienen in:Quaternary science reviews : the international multidisciplinary research and review journal P. Strobel, T. Henning, M. Bliedtner, S. Mosher, H. Rahimova, T. Haberzettl, K. Kirsten, E. Lehndorff, M. Power, M. Zech, R. Zech
    Fire is a natural phenomenon along South Africa's southern Cape coast, but identifying its climatic drivers has been a subject of considerable debate. This study investigates the hydroclimatic and fire dynamics from a 9.6 m sediment core from Vankervelsvlei covering the past 7.2 ka. The fen is located near the southern Cape coast within the year-round rainfall zone of South Africa. A reconstruction of hydroclimatic variability through time applies oxygen isotopes from hemicellulose-derived sugars and hydrogen isotopes from leaf wax-derived n-alkanes. Coupling both isotopes enables a reconstruction of the atmospheric source and seasonality of precipitation as well as estimating local relative humidity. Past trends in fire activity are inferred from macro-charcoal and polycyclic aromatic hydrocarbon (PAH) analyses, the latter serving as fire biomarkers. Results indicate high fire activity at Vankervelsvlei accompanied by generally moist conditions and a year-round rainfall regime linked to both Westerly-derived winter precipitation and Easterly- and locally-derived summer precipitation from 7.2⁺⁰.²/−₀.₂ to 4.5⁺⁰.³/−₀.₃ cal ka BP. From 4.5⁺⁰.³/−₀.₃ to 1.5⁺⁰.⁴/−₀.₂ cal ka BP, a shift to a Westerly-derived winter rainfall regime is identified. This variation features alongside reduced fire activity and persistent drought conditions as Easterly- and locally-derived summer precipitation decreased. From 1.5⁺⁰.⁴/−₀.₂ cal ka BP until present day, macro-charcoal and PAH accumulation rates show high fire activity. Paleoclimate evidence from the last two millennia suggests a variable climate with an overall increase in total moisture availability as contributions from both Westerly-derived winter precipitation and Easterly- and locally-derived summer precipitation support the year-round rainfall regime present today. Results from Vankervelsvlei support previous evidence from regional paleo-reconstructions, refining our understanding of the interplay between hydroclimatic variability and fire activity along South Africa's southern Cape coast. Our study discusses the role of large-scale climate modes, specifically the intensity of El Niño, as a potential driver of short-term hydroclimatic variability, which in turn drives fuel availability and fire activity at Vankervelsvlei during the Holocene.
    Universitätsbibliographie Jena:
    fsu_mods_00009880Externer Link

  10. A regional assessment of the deglaciation history of the Swiss Plateau based on newly obtained and re-evaluated Be-10 cosmic-ray exposure ages

    ErscheinungsjahrErschienen in:Quaternary Science Advances F. Hofmann, A. Groos, E. Garcia Morabito, J. Struck, C. Gnägi, A. Scharf, G. Rugel, S. Merchel, R. Zech
    During marine oxygen isotope stage (MIS) 2, the Swiss Plateau temporarily hosted large piedmont lobe glaciers that retreated after their maximum advance back to the fringe of the Alps. The presence of moraines in this region indicates that overall glacier recession was punctuated by repeated phases of ice-marginal stability and re-advances. The timing of these events in the region formerly covered by the eastern lobe of the Rhône (or Valais) glacier has been controversial and remains poorly constrained due to the lack of chronological data. To fill this gap, ¹⁰Be cosmic-ray exposure (CRE) dating was applied to erratic boulders inside the assumed MIS 2 maximum extent of this piedmont lobe. An erratic boulder at an ice-marginal position upstream from the suspected MIS 2 maximum extent gave an age of about 19 ka. Erratic boulders at a presumably younger ice-marginal position (Brästenberg position) yielded an average age of ca. 20 ka. However, several erratic boulders beyond the Brästenberg position gave internally consistent, but stratigraphically too young ages of ca. 17 ka. We cannot rule out that glacier recession from the Brästenberg position began no later than 17 ka. CRE dating of a moraine of a presumably younger ice-marginal position (Solothurn position) gave unrealistically old ages and an incredibly young age (86 ka, 40 ka, and 4 ka). Carbon-14 CRE dating should be applied to provide additional information on the last deglaciation of the Swiss Plateau. Nevertheless, despite outlying ages, the presented chronological data contribute to an overall consistent and increasingly refined chronology of the last deglaciation of the Swiss Plateau when compared with 59 previously published CRE ages.
    Universitätsbibliographie Jena:
    fsu_mods_00009370Externer Link

  11. Holocene vegetation, fire, climate dynamics and human impact in the upper Orkhon Valley of the Khangai Mountains, Mongolia

    ErscheinungsjahrErschienen in:Quaternary science reviews : the international multidisciplinary research and review journal C. Barhoumi, M. Bliedtner, R. Zech, H. Behling
    The Upper Orkhon Valley, located in the Khangai Mountains of Central Mongolia, is mainly covered by a forest-steppe ecosystem. This is an interesting area to study because its vegetation dynamics might have been influenced by climatic and anthropogenic drivers. This study investigates the dynamics of vegetation (pollen), human activity (pollen and NPP) and fire activity (macro-charcoal) from a lacustrine sediment core from lake Shireet Naiman Nuur, covering the last 7400 cal yr BP. The results of the pollen analysis showed a continual and constant decline of tree species in favour of the development of grasslands. Fire activity was more intense (high peak magnitude) during the mid Holocene, while it became more frequent but less intense from 5000 cal yr BP onwards, when herbaceous taxa became more present. The NPP analysis suggest that the study site was free of human activity from 7400 to 3500 cal yr BP, whereas the traces of the development of human societies that took place in the Orkhon Valley, such as pastoralism and grazing activities, have been demonstrated by the increase in coprophilous fungi and the Poaceae Cerealia-type pollen around 3200 cal yr BP, although its impact seems to have remained low.
    Universitätsbibliographie Jena:
    fsu_mods_00012911Externer Link

  12. Multi-proxy reconstruction of the last millennium paleo-environmental conditions from Lake Höglwörth, Southern Germany

    Erscheinungsjahr S. Acharya
    Universitätsbibliographie Jena:
    fsu_mods_00013477Externer Link
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