A first Holocene leaf wax isotope-based paleoclimate record from the semi-humid to semi-arid south-eastern Caucasian lowlands     

Marcel Bliedtner  Roland Zech  Jana Zech  Imke Schäfer  Hans von Suchodoletz 《第四纪科学杂志》2020,35(5):625-633

The Holocene paleoclimate of the Caucasus region is rather complex and not yet well understood: while existing studies are mainly based on pollen records from high-altitude and humid lowland regions, no records are available from the semi-humid to semi-arid south-eastern Caucasian lowlands. Therefore, this study investigated compound-specific δ²H and δ¹³C isotopes of leaf wax biomarkers from Holocene floodplain soils in eastern Georgia. Our results show that the leaf wax δ²H signal from the paleosols mostly reflects changes in the moisture source and its isotopic composition. Depleted δ²H values before ~8 cal ka bp change towards enriched values after ~5 cal ka bp and become again depleted after ~1.6 cal ka bp. This trend could be caused by Holocene changes of the isotopic compositions of the Black and eastern Mediterranean Sea, and/or by varying contribution of both moisture sources linked with the North Atlantic Oscillation. The leaf wax δ¹³C signal from the paleosols directly indicates varying local water availability and drought stress. Depleted δ¹³C values before ~8 and after ~5 cal ka bp indicate wetter local conditions with higher water availability, whereas more enriched values during the middle Holocene (~8 until at least 5 cal ka bp ) indicate drier conditions with increased drought stress.  相似文献   

Status and outlook of hiking trails in the central part of the Low Tatra Mountains in Slovakia between 1980–1981 and 2013–2014     

HRN?IAROVá Tatiana  KENDERESSY Pavol  ?PULEROVá Jana  VLACHOVI?OVá Miriam  PISCOVá Veronika  DOBROVODSKá Marta 《山地科学学报》2018,15(8):1615-1632

This study presents a methodology for assessment of the condition of hiking trails (HTs) and their impact zones in the central part of the Low Tatra mountain range, based on comparison of two complex data sets gathered in 33 years apart. The first field investigation was performed in 1980 and 1981, and the second in 2013 and 2014. The main goal was to perform a landscape typology in order to assess the susceptibility of landscape complexes to occurrence of anthropogenic and natural destruction processes and to assess the condition and prospects of HTs and their impacts on the adjacent alpine environment. Landscape complexes were characterised by selected abiotic, biotic and technical parameters of HTs and their impact zones. Due to the high variability of these parameters over the length of the HTs, we had to decide on how to map them. This was done using a square grid with 100 m-sized cells. For each cell with HT, the parameters were assigned the typical value within that cell. In total, 26.3 km of HT were studied, stretching over 266 grid cells. On comparison of the two data sets, it was seen that, 64% (171 grid cells) display a generally positive condition, with 54% (143 grid cells) even exhibiting significant improvement or continuously positive state of their condition. 36% (95 grid cells) were in bad condition, including 3% (9 grid cells) whose state had deteriorated, and 2% (6 grid cells) whose state had significantly deteriorated, in the time between the two assessments.  相似文献   

The first uv studies of the optical candidate for the X-ray source 1118-61     

M. J. Coe  B. J. Payne 《Astrophysics and Space Science》1985,109(1):175-181

The X-ray pulsator, 1118-61, discovered in 1975 by the Ariel-5 satellite, has been observed for the first time at UV wavelengths using IUE. Its UV spectrum clearly identifies the optical counterpart as a Be star similar to that seen in other X-ray pulsators. From the 2200 Å absorption feature a distance estimate of 4 kpc is obtained and the carbon-IV profile reveals the mass loss rate from the primary. The discrepancy seen in other similar systems between the optical/UV mass loss rate and that needed to power the X-ray source is also observed in this source. Possible models are reviewed.  相似文献   

Biogeographical drivers of ragweed pollen concentrations in Europe     

Matyasovszky  István  Makra  László  Tusnády  Gábor  Csépe  Zoltán  Nyúl  László G.  Chapman  Daniel S.  Sümeghy  Zoltán  Szűcs  Gábor  Páldy  Anna  Magyar  Donát  Mányoki  Gergely  Erostyák  János  Bodnár  Károly  Bergmann  Karl-Christian  Deák  Áron József  Thibaudon  Michel  Albertini  Roberto  Bonini  Maira  Šikoparija  Branko  Radišić  Predrag  Gehrig  Regula  Rybníček  Ondřej  Severova  Elena  Rodinkova  Victoria  Prikhodko  Alexander  Maleeva  Anna  Stjepanović  Barbara  Ianovici  Nicoleta  Berger  Uwe  Seliger  Andreja Kofol  Weryszko-Chmielewska  Elżbieta  Šaulienė  Ingrida  Shalaboda  Valentina  Yankova  Raina  Peternel  Renata  Ščevková  Jana  Bullock  James M. 《Theoretical and Applied Climatology》2018,133(1-2):277-295

Theoretical and Applied Climatology - The drivers of spatial variation in ragweed pollen concentrations, contributing to severe allergic rhinitis and asthma, are poorly quantified. We analysed the...  相似文献   

Using cryptotephras to extend regional tephrochronologies: An example from southeast Alaska and implications for hazard assessment     

Richard Payne  Jeffrey Blackford 《Quaternary Research》2008,69(1):42-55

Cryptotephrochronology, the use of hidden, diminutive volcanic ash layers to date sediments, has rarely been applied outside western Europe but has the potential to improve the tephrochronology of other regions of the world. Here we present the first comprehensive cryptotephra study in Alaska. Cores were extracted from five peatland sites, with cryptotephras located by ashing and microscopy and their glass geochemistry examined using electron probe microanalysis. Glass geochemical data from nine tephras were compared between sites and with data from previous Alaskan tephra studies. One tephra present in all the cores is believed to represent a previously unidentified eruption of Mt. Churchill and is named here as the ‘Lena tephra’. A mid-Holocene tephra in one site is very similar to Aniakchak tephra and most likely represents a previously unidentified Aniakchak eruption, ca. 5300-5030 cal yr BP. Other tephras are from the late Holocene White River eruption, a mid-Holocene Mt. Churchill eruption, and possibly eruptions of Redoubt and Augustine volcanoes. These results show the potential of cryptotephras to expand the geographic limits of tephrochronology and demonstrate that Mt. Churchill has been more active in the Holocene than previously appreciated. This finding may necessitate reassessment of volcanic hazards in the region.  相似文献   

Spectroscopic and bond-topological investigation of interstitial volatiles in beryl from Slovakia   总被引：1，自引：0，他引：1  

Jana Fridrichová  Peter Bačík  Valéria Bizovská  Eugen Libowitzky  Radek Škoda  Pavel Uher  Daniel Ozdín  Martin Števko 《Physics and Chemistry of Minerals》2016,43(6):419-437

Nine beryl samples from Western Carpathians, Slovakia, were investigated by infrared and Raman spectroscopy and differential thermal analysis. Two types of water H₂O I and H₂O II were detected. Infrared spectroscopy proved the presence of water type I and II in the presence of alkali cations with several bands: (1) symmetric stretching vibration—ν₁; (2) antisymmetric stretching mode—ν₃; (3) bending vibration—ν₂. The presence of singly and doubly coordinated type II water (IIs and IId) was confirmed by single-crystal IR spectroscopy. From Raman spectra a band at 3606 cm^?1 was assigned to ν₁ of water type I and the range of 3597–3600 cm^?1 to water type II. The presence of doubly coordinating water indicates a relatively highly hydrated environment with the presence of alkali ions including Na as the dominant cation coordinated by H₂O II. CO₂ bands were detected only by single-crystal IR spectroscopy. Thermal analysis proved total water loss in the range of 1.4–2.0 wt% and three main dehydration events. Based on the study of bond-topological arrangements two molecules of H₂O IId are each bound with two H···O1 bonds and one Na–O_W bond with an angular distortion, and by releasing one H₂O molecule more stable H₂O IIs is produced. The H₂O I molecule is bound only by two equivalent hydrogen bonds. The H₂O IIs molecule with a Na–O_W bond strength of 0.28 vu and two H···O1 bonds of 0.14 vu without any forced angular distortion is the most stable of all.  相似文献   

Living the good life? The rise of urban mixed-use enclaves in Metro Manila     

Jana Maria Kleibert  Lisa Kippers 《Urban geography》2016,37(3):373-395

Gated communities and other forms of privatized enclaves have become features of many cities. The rise of urban mixed-use enclaves, which integrate functions of work, entertainment and living, is a relatively new and understudied phenomenon that is expanding rapidly throughout the Global South. In this article, we advance the concept of enclave urbanism through a case study of Eastwood City in Metro Manila, the Philippines. We trace the enabling factors for mixed-use enclave creation and assess how the different functions are marketed and integrated in practice into one “live–work–play” development. Based on extensive qualitative research, we argue that the global capital accumulation strategy of real estate developers leads to a strong focus on production and entertainment functions, but neglects questions of liveability. We reflect on the implications of our findings for mega-urban regions and urban studies research.  相似文献   

The normal force on a flat planing plate, including low length to beam ratios     

Peter R. Payne 《Ocean Engineering》1981,8(3):221-258

A previous paper (Payne, 1980) developed the theory of a slender planing surface from first principles, and found it to agree with experiment without the need for “factors determined from experiments”. The theory broke down, however, for low wetted length to beam ratios because the flow is then no longer two-dimensional in character in respect to a section normal to the flow. It is in a transition to the condition where, at very small length to beam ratios, it is two-dimensional in a vertical plane parallel to the flow, rather than normal to it.In the present paper we determine, albeit somewhat heuristically, the virtual mass coefficient of a flat plate in the transition region. This is then employed to compute the normal force on a planing plate in both steady state and transient motion. For both conditions the agreement with the available experimental data is within the accuracy of the data.Both theory and experiment lead to the conclusion that certain traditional concepts in the of trim angle and Pierson's suggestion that ‘wetted length’ is more fundamental than the length of intersection with the still water surface. The widespread acceptance of this latter suggestion has meant that a key parameter in the present theory—the nominal or undisturbed water intersection length—is almost never measured in modern experiments. Thus, since we could not find any modern data, we had to appeal to the classical experimental papers which originated the scientific study of planing in the thirties and forties. Oddly, the earliest papers gave data which had much less scatter than the later papers.  相似文献   

Publishing the ICES Journal of Marine Science: facing fresh challenges in a competitive environment     

Payne  Andrew I. L.; Kennedy  Cathy 《ICES Journal of Marine Science》2007,64(1):1-2

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Hydrography of the East Shetland Basin in relation to decadal North Sea variability   总被引：2，自引：0，他引：2  

Turrell  W. R.; Slesser  G.; Payne  R.; Adams  R. D.; Gillibrand  P. A. 《ICES Journal of Marine Science》1996,53(6):899-916

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