scholarly journals How dry was the Younger Dryas? Evidence from a coupled δ<sup>2</sup>H-δ<sup>18</sup>O biomarker paleohygrometer, applied to the Lake Gemündener Maar sediments, Western Eifel, Germany

2018 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Vegetation Period ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Natural Climate

Abstract. The Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in Central Europe during the Late Glacial, are considered crucial for understanding rapid natural climate change in the past. The sediments from Maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from Lake Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf wax-derived lipid biomarkers (n-alkanes C27 and C29) and hemicellulose-derived sugar biomarkers (arabinose), respectively. Both δ2H and δ18O are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. This enables the coupling of the results via a δ2H-δ18O biomarker paleohygrometer approach and allows calculating past relative air humidity values, which is the major advantage of the applied approach. Fundamental was the finding that the isotopic enrichment of leaf water due to evapotranspiration depends mainly on relative humidity. We hence use the coupled δ2H-δ18O biomarker approach to reconstruct the deuterium-excess of leaf water and in turn relative air humidity values corresponding to the vegetation period and daytime (RHdv). Most importantly, the results of the coupled δ2H-δ18O biomarker paleohygrometer approach (i) support a two-phasing of the Younger Dryas, i.e. a relative wet phase (on Allerød level) followed by a drier Younger Dryas ending, (ii) do not corroborate overall drier climatic conditions characterising the Younger Dryas or a two-phasing with regard to a first dry and cold Younger Dryas phase followed by a warmer period along with increasing precipitation amounts, and (iii) suggest that the amplitude of RHdv changes during the Early Holocene was more pronounced compared to the Younger Dryas. One possible driver for the unexpected Lake Gemündener Maar RHdv variations could be the solar activity.

scholarly journals How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

2019 ◽  
Vol 15 (2) ◽  
pp. 713-733 ◽  
Author(s):  
Johannes Hepp ◽  
Lorenz Wüthrich ◽  
Tobias Bromm ◽  
Marcel Bliedtner ◽  
Imke Kathrin Schäfer ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Leaf Water ◽  
Early Holocene ◽  
Unexpected Finding ◽  
Temperature Dependent ◽  
The Past ◽  
Natural Climate

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

The influence of climatic conditions on physiological and behavioural parameters in dairy cows kept in open stables

2004 ◽  
Vol 78 (1) ◽  
pp. 139-147 ◽  
Author(s):  
M. Zähner ◽  
L. Schrader ◽  
R. Hauser ◽  
M. Keck ◽  
W. Langhans ◽  
...  
Keyword(s):  
Mean Value ◽  
Climatic Conditions ◽  
Air Humidity ◽  
Lactating Cows ◽  
Relative Air Humidity ◽  
Infra Red ◽  
Commercial Farms ◽  
Humidity Index ◽  
Body Surface Temperature ◽  
Night And Day

AbstractThis study aimed to assess whether cows are able to cope with the range of climatic conditions they are exposed to in open stables on commercial farms in central Europe. On each of four farms, ten lactating cows were observed over a total of five weeks in winter, spring and summer. Based on continuous measurements of air temperature (–13·8 to 28·7ºC) and relative air humidity (0·26 to 0·99), a mean value of a temperature humidity index (THI) was calculated for each farm and each observation day for night and day.THI had significant effects on skin temperature and body surface temperature (infra-red thermography) both during night and day. Rectal temperature, duration of lying and cortisol concentration in the milk was significantly affected by THI during the day but not during the night. Heart rate and frequency of lying did not significantly covary with THI. Differences between farms and interactions between THI and farm were significant for most parameters. These results suggest that the climatic conditions during the day induced stronger thermoregulatory responses than the conditions during the night. Within the measured range of climatic conditions the cows were hardly exposed to severe cold or heat stress.

scholarly journals A major hydrobiological change in Dasht-e Arjan Wetland (southwestern Iran) during the late glacial – early Holocene transition revealed by subfossil chironomids

2019 ◽  
Vol 56 (8) ◽  
pp. 848-856
Author(s):  
Cyril Aubert ◽  
Morteza Djamali ◽  
Matthew Jones ◽  
Hamid Lahijani ◽  
Nick Marriner ◽  
...  
Keyword(s):  
Lake Level ◽  
Regional Scale ◽  
Younger Dryas ◽  
Late Glacial ◽  
Early Holocene ◽  
Geochemical Data ◽  
The Holocene ◽  
Chironomus Plumosus ◽  
Subfossil Chironomids ◽  
Southwestern Iran

The late glacial – early Holocene transition is a key period in the earth’s history. However, although this transition is well studied in Europe, it is not well constrained in the Middle East and palaeohydrological records with robust chronologies remain scarce from this region. Here we present an interesting hydrobiological record showing a major environmental change occurring in the Dasht-e Arjan Wetland (southwestern Iran, near to Persepolis) during the late glacial – early Holocene transition (ca. 11 650 years cal BP). We use subfossil chironomids (Insecta: Diptera) as a proxy for hydrological changes and to reconstruct lake-level fluctuations. The Arjan wetland was a deep lake during the Younger Dryas marked by a dominance of Chironomus plumosus/anthracinus-type, taxa adapted to anoxic conditions of deep waters. At the beginning of the Holocene, a drastic decrease (more than 80% to less than 10%) of Chironomus plumosus/anthracinus-type, combined with diversification of littoral taxa such as Polypedilum nubeculosum-type, Dicrotendipes nervosus-type, and Glyptotendipes pallens-type, suggests a lake-level decrease and a more vegetalized aquatic environment. We compare and contrast the chironomid record of Arjan with a similar record from northwestern Iran. The palaeoclimatic significance of the record, at a local and regional scale, is subsequently discussed. The increase in Northern Hemisphere temperatures, inferred by geochemical data from NGRIP, at the beginning of the Holocene best explains the change from the Younger Dryas highstand to early Holocene lowstand conditions in the Dasht-e Arjan wetland. However, a contribution of the meltwater inflow from small local glaciers in the catchment basin is not excluded.

A multiproxy study of Younger Dryas and Early Holocene climatic conditions from the Grabia River paleo-oxbow lake (central Poland)

2015 ◽  
Vol 438 ◽  
pp. 34-50 ◽  
Author(s):  
Dominik Pawłowski ◽  
Mateusz Płóciennik ◽  
Stephen J. Brooks ◽  
Tomi P. Luoto ◽  
Krystyna Milecka ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Climatic Conditions ◽  
Early Holocene ◽  
Oxbow Lake ◽  
Central Poland

scholarly journals Palynology and Archaeology of Late Vistulian and Early Holocene Sites in Lubuskie Lake District, Western Poland

2014 ◽  
Vol 31 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Iwona Okuniewska-Nowaczyk ◽  
Iwona Sobkowiak-Tabaka
Keyword(s):  
Small Area ◽  
Younger Dryas ◽  
Late Glacial ◽  
Early Holocene ◽  
Lake District ◽  
Multidisciplinary Research ◽  
Late Vistulian ◽  
Palynological Spectrum ◽  
History Of ◽  
Palynological Records

Abstract The Lubuskie Lake District played an important part in recolonisation of the Polish Plain due to its location and the character of the terrain. Despite that, it is and especially its northern part, poorly explored regarding both history of Late Glacial and early Holocene settlements, and the natural environment. The paper presents results of multidisciplinary research in this area. The most spectacular discoveries were connected with remains of settlements of the Hamburgian culture societies at Myszęcin - currently the richest site of this culture over the entire North European Plain. In the vicinity of this site several Late Palaeolithic and Mesolithic settlements of varied functions were recorded. First palynological records came from the Younger Dryas sediments in this area. In a log with a palynological spectrum comprising Younger Dryas and the beginning of the Holocene, a charcoal dust was found and it could indicate human activity as humans lived at a lake shore. An important complement to the image of the Late Glacial settlement at the Lubuskie Lake District was provided by the research near Lubrza that resulted in data regarding settlements of the Federmesser and Świderian culture societies. This region was not typical in a palynological spectrum of deposits during Allerød but also indicated highly diversified thickness of basal peat in a small area.

scholarly journals Influence of Temperature‑Humidity Relations During Years on Milk Production and Quality

2017 ◽  
Vol 65 (1) ◽  
pp. 211-218 ◽  
Author(s):  
Renáta Toušová ◽  
Jaromír Ducháček ◽  
Luděk Stádník ◽  
Martin Ptáček ◽  
Sylvana Pokorná
Keyword(s):  
Protein Content ◽  
Milk Production ◽  
Air Temperature ◽  
Somatic Cells ◽  
Climatic Conditions ◽  
Holstein Cows ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Daily Milk Production ◽  
Daily Milk

The aim of this study was to evaluate influence of climatic conditions represented by daily air temperature and relative air humidity on indicators of Holstein cows’ milk quality and production. The first dataset represented individual milk production in day of milk performance recording (milk kg, fat %, protein %, and somatic cells count thous.*ml−1). The second dataset represented total daily milk characteristics of herd (milk kg, fat %, protein % and somatic cells count thous.*ml−1). A total of 654 Holstein cows were observed and evaluated. Both datasets were evaluated in relation to selected external influences (year, month, average daily air temperature, and average daily relatively air humidity). Statistical analysis was performed using SAS 9.3, and UNIVARIATE, REG and GLM procedure. Three groups of daily air temeperature (< 4.4 °C; 4.4 – 13.2 °C; > 13.2 °C), and daily relative air humidity (< 65.3 %; 65.3 – 80.4 %; > 80.4 %) were conducted for evaluation. Significant (P < 0.05) linear regressions were computed among daily air temperature and all milk production indicators, except of somatic cells count attribute. The highest individual daily milk production (35.94 kg, P < 0.01), and protein content (3.41 %, P < 0.01) were achieved with the highest average daily air temperature. Opposite results were observed for milk yield of herd as well as protein content. Average daily relative air humidity had lower influence on individual and bulk milk samples. The better results were achieved for both datasets (individual and bulk samples) in groups (65.3 – 80.4 %; > 80.4 %) of average daily relative air humidity. Obtained results point out importance of outdoor climatic parameters monitoring and preventive measures of climatic conditions in the stable.

scholarly journals Late Glacial and Early Holocene human demographic responses to climatic and environmental change in Atlantic Iberia

2020 ◽  
Vol 376 (1816) ◽  
pp. 20190724 ◽  
Author(s):  
T. Rowan McLaughlin ◽  
Magdalena Gómez-Puche ◽  
João Cascalheira ◽  
Nuno Bicho ◽  
Javier Fernández-López de Pablo
Keyword(s):  
Population Growth ◽  
Quantitative Methods ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Early Holocene ◽  
Food Sources ◽  
Resource Base ◽  
Temporal Models ◽  
Spatio Temporal ◽  
Successive Generations

Successive generations of hunter–gatherers of the Late Glacial and Early Holocene in Iberia had to contend with rapidly changing environments and climatic conditions. This constrained their economic resources and capacity for demographic growth. The Atlantic façade of Iberia was occupied throughout these times and witnessed very significant environmental transformations. Archaeology offers a perspective on how past human population ecologies changed in response to this scenario. Archaeological radiocarbon data are used here to reconstruct demographics of the region over the long term. We introduce various quantitative methods that allow us to develop palaeodemographic and spatio-temporal models of population growth and density, and compare our results to independent records of palaeoenvironmental and palaeodietary change, and growth rates derived from skeletal data. Our results demonstrate that late glacial population growth was stifled by the Younger Dryas stadial, but populations grew in size and density during the Early to Middle Holocene transition. This growth was fuelled in part by an increased dependence on marine and estuarine food sources, demonstrating how the environment was linked to demographic change via the resource base, and ultimately the carrying capacity of the environment. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

scholarly journals Coupling δ<sup>2</sup>H and δ<sup>18</sup>O biomarker results yields information on relative humidity and isotopic composition of precipitation – a climate transect validation study

2015 ◽  
Vol 12 (12) ◽  
pp. 3913-3924 ◽  
Author(s):  
M. Tuthorn ◽  
R. Zech ◽  
M. Ruppenthal ◽  
Y. Oelmann ◽  
A. Kahmen ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Isotopic Composition ◽  
Validation Study ◽  
Leaf Water ◽  
Deuterium Excess ◽  
Air Humidity ◽  
Leaf Wax ◽  
Relative Air Humidity ◽  
Paleoclimate Reconstructions ◽  
Hydrogen Isotopic Composition

Abstract. The hydrogen isotopic composition (δ2H) of leaf waxes, especially of n-alkanes (δ2Hn-alkanes), is increasingly used for paleohydrological and paleoclimate reconstructions. However, it is challenging to disentangle past changes in the isotopic composition of precipitation and changes in evapotranspirative enrichment of leaf water, which are both recorded in leaf wax δ2H values. In order to overcome this limitation, Zech M. et al. (2013) proposed a coupled δ2Hn-alkanes–δ18Osugar biomarker approach. This coupled approach allows for calculating (i) biomarker-based "reconstructed" δ2Hδ18O values of leaf water (δ2Hδ18Oleaf water), (ii) biomarker-based reconstructed deuterium excess (d-excess) of leaf water, which mainly reflects evapotranspirative enrichment and which can be used to reconstruct relative air humidity (RH) and (iii) biomarker-based reconstructed δ2Hδ18Oprecipitation values. Here we present a climate transect validation study by coupling new results from δ2H analyses of n-alkanes and fatty acids in topsoils along a climate transect in Argentina with previously measured δ18O results obtained for plant-derived sugars. Accordingly, both the reconstructed RH and δ2Hδ18Oprecipitation values correlate highly significantly with actual RH and δ2Hδ18Oprecipitation values. We conclude that compared to single δ2Hn-alkane or δ18Osugar records, the proposed coupled δ2Hn-alkane–δ18Osugar biomarker approach will allow more robust δ2Hδ18Oprecipitation reconstructions in future paleoclimate research. Additionally, the proposed coupled δ2Hn-alkane–δ18Osugar biomarker approach allows for the establishment of a "paleohygrometer", more specifically, the reconstruction of mean summer daytime RH changes/history.

scholarly journals Climate and base-level controlled fluvial system change and incision during the last glacial–interglacial transition, Roer river, the Netherlands – western Germany

2016 ◽  
Vol 96 (2) ◽  
pp. 71-92 ◽  
Author(s):  
C. Kasse ◽  
R.T. Van Balen ◽  
S.J.P. Bohncke ◽  
J. Wallinga ◽  
M. Vreugdenhil
Keyword(s):  
The Netherlands ◽  
Younger Dryas ◽  
System Change ◽  
Late Glacial ◽  
Sediment Supply ◽  
Early Holocene ◽  
Forest Recovery ◽  
Fluvial System ◽  
Base Level ◽  
Western Germany

AbstractThe fluvial development of the Roer river in the southeastern Netherlands and western Germany is presented for the Late Pleniglacial, Late-glacial and Early Holocene periods. Reconstruction of fluvial-style changes is based on geomorphological and sedimentological analysis. Time control comes from correlation to the pollen-based biochronostratigraphic framework of the Netherlands combined with independent optically stimulated luminescence (OSL) ages. At the Pleniglacial to Late-glacial transition a system and channel pattern change occurred from an aggrading braided to an incising meandering system. Rapid rates of meander migration, as established for the Late-glacial by optical dating, were likely related to the sandy nature of the substratum and the Late-glacial incision of the Meuse that resulted in a higher river gradient in the downstream part of the Roer. In the Roer valley the Younger Dryas cooling is not clearly reflected by a fluvial system response, but this may also be related to Holocene erosion of Younger Dryas fluvial forms. An important incision and terrace formation was established at the Younger Dryas to Early Holocene transition, probably related to forest recovery, reduced sediment supply and base-level lowering of the Meuse. The results of this study show a stepwise reduction in the number of channel courses from a multi-channel braided system in the Pleniglacial, to a double meander-belt system in the Late-glacial and a single-channel meandering system in the Early Holocene. The results show that the forcing factors of fluvial-system change in the Roer valley are climate change (precipitation, permafrost and vegetation) and downstream base-level control by the Meuse.

scholarly journals Influence of Impregnation with Modified Starch of a Paper Core on Bending of Wood-Based Honeycomb Panels in Changing Climatic Conditions

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 395
Author(s):  
Michał Słonina ◽  
Dorota Dziurka ◽  
Marta Molińska-Glura ◽  
Jerzy Smardzewski
Keyword(s):  
Mechanical Properties ◽  
Statistical Analysis ◽  
Significant Relationship ◽  
Climatic Conditions ◽  
Bending Test ◽  
Modified Starch ◽  
Air Humidity ◽  
Absorbed Energy ◽  
Three Point Bending ◽  
Relative Air Humidity

The main objective of the study was to determine the effect of impregnation of the paper core with acetylated starch on the mechanical properties and absorbed energy in the three-point bending test of wood-based honeycomb panels under varying temperatures and relative air humidity conditions. Nearly six hundred beams in various combinations, three types of facings, three core cells geometries, and two paper thicknesses were tested. The experiment results and their statistical analysis prove a significant relationship between the impregnation of paper with modified starch and mechanical properties. The most effective in absorbing energy, the honeycomb panels, consisted of a core with a wall thickness of 0.25 mm and a particleboard facing.

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