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Wyszukujesz frazę "luminescence" wg kryterium: Temat


Wyświetlanie 1-8 z 8
Tytuł:
Analysis of aromatic fractions of low-temperature coal tars with the use of synchronous luminescence technique
Autorzy:
Matuszewska, A.
Czaja, M.
Powiązania:
https://bibliotekanauki.pl/articles/1204923.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
synchronous luminescence
coal primary tar
Opis:
The qualitative analysis by synchronous luminescence technique was performed on aromatic fractions of primary tars obtained from humic and sapropelic coals (from Upper Silesia Basin). The synchronous luminescence technique, called also the technique of spectral fractionation, consists in the record of a spectrum at the constant difference between the positions of emission and excitation monochromators (Dl). This difference is calculated as a result of subtraction of effective emission and excitation wavelengths characterising compounds identified in investigated mixture. In relation with conventional luminescence technique, giving broad, low resolved bands in the conditions of ambient temperature, the synchronous luminescence technique enables to obtain well resolved and simplified spectra that facilitate the identification of individual components of the mixture. The application of this technique to analysis of aromatic fractions composition of primary tars from coals of various genesis and technological properties (sapropelic and humic coals) has shown a general similarity of composition with predomination of aromatic compounds containing 2-4 condensed rings. In the sample derived from sapropelic coal, a markedly higher intensity of bands is observed, attributed to aromatics of lower condensation degree (2-3 condensed rings), in relation with the bands of aromatics with higher intensity (3-4 condensed rings). The reverse relation is observed for sample from humic coal. In both analysed samples, a series of the following individual compounds has been identified from groups of aromatics: naphthalenes, acenaphthenes, benzofluorenes, anthracenes, pyrenes, and benz(a)anthracenes. Smaller amounts of benz(a)pyrenes, benz(ghi)perylene, and 3, 4-9, 10-dibenzopyrene were also encountered. The technique of synchronous luminescence made possible, therefore, the identification of individual components of complex mixture of aromatic compounds in coal derived products. This technique is thus of great value for the characteristics of aromatic compounds in thermolysis products of coal, in the cognitive aspect, as well as in monitoring of environment.
Źródło:
Polish Geological Institute Special Papers; 2002, 7; 181-188
1507-9791
Pojawia się w:
Polish Geological Institute Special Papers
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stratigraphic interpretation of loess in the marginal zone of the Dnieper I ice sheet and the evolution of its landscape after deglaciation (Dnieper Upland, Ukraine)
Autorzy:
Komar, M.
Łanczont, M.
Fedorowicz, S.
Gozhik, P.
Mroczek, P.
Bogucki, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060425.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
loess
palaeosol
Dnieper
Pleistocene
palaeogeography
palynology
luminescence dating
Opis:
Litho-, pedo- and palynological analyses constrained by radiometric dating of two loess-palaeosol sequences, Nahirne and Velyka Andrusivka, exposed in a cliff at the eastern edge of the Dnieper Upland, Ukraine, document regional environmental changes in the western marginal zone of the Dnieper lobe. The postglacial loess sedimentation cycle was initiated during MIS 8, immediately after the ice sheet recession. On the basis of palaeorelief analysis, subsequent morphogenetic stages of the original postglacial relief, associated with the modifying and masking role of the loess, and destructive slope processes were reconstructed. Periglacial steppe with consistently present scattered trees formed the Pleistocene landscape in the Middle Dniester area during the last three glacial periods. In such an environment, the following loess beds, correlated with marine isotope stages (MIS), were deposited: Dnieper (dn) - MIS 8, Tyasmyn (ts) - MIS 6, Uday (ud) - MIS 4 and Bug (bg) - MIS 2. During the last two warm periods: Kaydaky (kd) - MIS 7 and Pryluky (pl) - MIS 5, the landscape was not fully forested. As a result, the individual palynological features of these soils show a diverse character. The TL and OSL dates form a sequence with numerous inversions that are difficult to interpret. Although these data do not significantly influence the interpretation, they show that: 1) there are loesses that undoubtedly formed after the maximum extent of the ice sheet by short-distance transport of dust material from local fresh glacial deposits and the underlying Paleogene rocks; 2) date distortions result from the activities of an exceptionally rich pedofauna that has contaminated the material not only in the soil sections of the profile but also in the adjacent loess. It is possible to delimit a few stages of pedofaunal activity in each of the soil units.
Źródło:
Geological Quarterly; 2018, 62, 3; 536--552
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence dating of the Volochysk section : a key Podolian loess site (Ukraine)
Autorzy:
Fedorowicz, S.
Łanczont, M.
Mroczek, P.
Bogucki, A.
Standzikowski, K.
Moska, P.
Kusiak, J.
Bluszcz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060446.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
loess-palaeosol sequence
luminescence dating
quartz
polymineral fractions
Podolia
Opis:
The Volochysk site belongs to important and unique loess sites in the Podolia Upland (W Ukraine) because it contains relatively well-developed loess deposits representing the last and penultimate glacial cycles. This loess-palaeosol sequence consists of pedocomplex S1 (MIS 5) developed on loess L2, and loess L1 (MIS 4-2) with the palaeosols of lower, interstadial rank. In this sequence, different periglacial structures were found, including the largest ones of ice-wedge cast type. Different quartz and polymineral fractions separated from the samples collected in the Volochysk site were dated using luminescence methods (SAR OSL, post-IR IRSL and TL) in three Polish luminescence laboratories in Gdańsk, Gliwice and Lublin. In total, 69 luminescence dating results were obtained for 18 samples. The methodological and research aims were to carry out mutual verification of the obtained dating results as well as to analyse and interpret the differences between them, and to determine the age of distinguished deposit layers and the period of cryogenic activities. The luminescence dates of the sediments, which were deposited during MIS 2, 3 and 4, corresponded fairly well to the ages attributed to these stages. They also indicate the age of periglacial phenomena. However, the TL dates were generally older than the OSL ones, especially those obtained for the sediments deposited during MIS 5 and 6. The results of the research of the Volochysk sequence were compared with those obtained in past years for the loess deposits of the Volhynian Upland (north of Podolia) during similar inter-laboratory analyses conducted to determine their age. The results of OSL datings of the older deposits (MIS 5 and MIS 6) are underestimated irrespective of the used method, and the type (quartz, polymineral) and size of grains. Numerous attempts were made to explain this phenomenon, which, however, give no answer. It was only found that this underestimation corresponded to the equivalent dose value of ~150 Gy.
Źródło:
Geological Quarterly; 2018, 62, 3; 729--744
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of the Holocene foredune plain in the Narva-Jõesuu area, eastern Gulf of Finland
Autorzy:
Rosentau, A.
Jõeleht, A.
Plado, J.
Aunap, R.
Muru, M.
Eskola, K. O.
Powiązania:
https://bibliotekanauki.pl/articles/2060031.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holocene
Baltic Sea
foredunes
luminescence dating
ground penetrating radar
lidar
Opis:
The morphogenesis and inner structure of the Holocene foredune plain in the Narva-Joesuu area, eastern Gulf of Finland, were studied using optically stimulated luminescence (OSL) dating, ground-penetrating radar (GPR) study and interpretation of airborne LIDAR elevation data. The results show that the Narva-Joesuu foredune plain consists of ca. 100 parallel coastal foredune ridges built of well-sorted fine sand underlain by gently (~7°) seaward-dipping sandy beach deposits. The distal part of the plain, which consists of at least 15 ridges, formed during the regressive phase of the Ancylus Lake/Early Litorina Sea, serving as a barrier for the lagoon behind it. A larger portion of ridges, with an average progradation rate of 0.26 m a-1, formed under conditions of falling relative sea level during the Litorina regression and was separated from the older foredune succession by a hiatus related to the Litorina transgression at 8.5-7.3 cal. ka BP. In the highest central part of the plain the foredune growth was interrupted by foredune instability and a re-blowing episode dated to 5.4 ± 0.9 ka BP which may correlate with a larger regional cooling at 5.8-5.1 cal. ka BP in the North Atlantic and central Europe. During the last 3000 years, the foredune progradation rate decreased to 0.19 m a-1, most probably because of decelerated land-uplift and increased human impact due to coastal protection.
Źródło:
Geological Quarterly; 2013, 57, 1; 89--100
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of sedimentological composition on OSL dating of glaciofluvial deposits : examples from Estonia
Autorzy:
Raukas, A.
Stankowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/2059710.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Pleistocene chronostratigraphy
deglaciation history
ice marginal formations
glaciofluvial deposits
luminescence dating
Opis:
We assess the suitability of luminescence (TL and OSL) dating techniques for establishing a precise Late Pleistocene chronology for the northern Baltic area, and show on the basis of the fine sand/coarse silt fraction of subaqueous deposits, how sedimentological composition influences the dates obtained. Turbidity, loading by fine suspended material, water depth, velocity of outwash streams and transport length, and also perhaps rapid night-time sedimentation and incorporation of older, unbleached particles are factors that variably influence the extent of bleaching of the luminescence signal, and thus, cause variability of dates obtained. Alongside reliable dates for "late-glacial" deposits between 11 000-15 000 OSL years BP, many entirely unreliable dates from 8 000 ±300 to 114 000 ±8 000 OSL years BP have been obtained. This means that the age determination of glaciofluvial deposits is extremely difficult in practice. This applies particularly to intermorainic sediments, the exact genesis of which is unknown. The paper is addressed to the investigators wishing to use luminescence dating techniques to establishing the Pleistocene chronostratigraphy of glaciofluvial deposits.
Źródło:
Geological Quarterly; 2005, 49, 4; 463--470
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Glacial and Holocene vegetation and climate history of an alpine wetland on the Qinghai-Tibetan Plateau
Autorzy:
Liu, D. L.
Chen, G.
Lai, Z.
Weis, H.
Zhou, G.
Peng, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059730.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Late Glacial
Holocene
Qinghai-Tibetan Plateau
alpine wetland
optically stimulated luminescence
pollen analysis
Opis:
This study provides a vegetation and climate history of an alpine wetland in the centre of China’s Qinghai–Tibetan Plateau (QTP) over the last 14.8 ka. High resolution climate proxies include vegetation (pollen), geochemical (Ba, Rb, δ13C) and physical (particle size and magnetic susceptibility) data; optically stimulated luminescence (OSL) and AMS radiocarbon dating were used to reconstruct the environmental changes in the wetland ecosystem. Based on physical and geochemical proxies, the sucession divided into five stratigraphic units encompassing time intervals of 14.76–14.31, 14.31–13.17, 13.17–4.47, 4.47–0.51 and 0.51–0 ka. The average sedimentation rate of all these units was 0.098 mm/a. The study showed that this ecosystem was sensitive to climate change.
Źródło:
Geological Quarterly; 2013, 57, 2; 261--268
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New luminescence ages reveal Early to Middle Weichselian deposits in central Latvia
Autorzy:
Lamsters, K.
Kalińska-Nartiša, E.
Zelčs, V.
Alexanderson, H.
Powiązania:
https://bibliotekanauki.pl/articles/2060383.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
optically stimulated luminescence (OSL) dating
subglacial bedforms
Early Weichselian
Middle Weichselian
central Latvia
Opis:
New optically stimulated luminescence (OSL) ages show that sandy deposits overlain by Late Weichselian subglacial till in central Latvia are of Early to Middle Weichselian age. The finer chronological resolution of unconsolidated sediment deposition in the Central Latvian Lowland (CLL) remains relatively unstudied, and here we provide a first characterisation of the deposits with respect to their age. Three OSL ages ranging between 84 ± 9 ka and 112 ± 11 ka suggest that the deposits studied in the CLL are of Early Weichselian age (MIS 5). We found no Middle Weichselian deposits in the CLL, and assume that any such younger sediments might have been eroded during the advance of the Zemgale Lobe in the Late Weichselian. One site, in the ice-marginal zone adjacent to the interlobate area, has nevertheless deposits dated to 44 ± 10 ka corresponding to the Middle Weichselian (MIS 3). Our results are compatible with existing ESR ages on three sets of Portlandia arctica shells from the central part of the lowland; the shells had been incorporated into glacial deposits during later glacial advances. Finally, our findings largely support ice-free conditions during the Early and Middle Weichselian in the middle and southern part of central Latvia.
Źródło:
Geological Quarterly; 2017, 61, 2; 480--490
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rate of loess accumulation in Europe in the Late Weichselian (Late Vistulian)
Autorzy:
Fedorowicz, S.
Łanczont, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059500.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
European loess
Upper Weichselian
mass accumulation rates (MAR)
TL age
optically stimulated luminescence (OSL)
Opis:
The European loess profiles provides evidence of changes in climate in the last glacial cycle. The final stage of loess accumulation took place in the youngest part of the last glacial (28 to 12 ka BP). Loess accumulated in two periods: from 28 to 18 ka BP and from 18 to 13 ka BP. These two stages were separated by a short phase of weaker aeolian activity and weak pedogenesis (initial tundra gleyed soils). The loess sedimentation rate can be defined as a mass accumulation rate (MAR ex pressed in g/m2/year). This value was calculated by Frechen et al. (2003) for several dozen loess sites across western and central Europe. In this paper we calculate the MAR for several loess sites in Poland and Ukraine. The MAR distribution across Poland and Ukraine is uneven in these two intervals. The MAR values oscillate between 100 to several thou sand g/m2/year. They markedly in crease eastwards, which may be explained by the latitudinal gradient of periglacial climate in the LateWeichselian (= Late Vistulian). The MAR distribution along a N-S trend confirms its large range in western and central Europe. However, the most easterly profiles (Polish and Ukrainian ones) show less variable thick nesses as the MAR was stable at a relatively low level from several hundred to more than a thou sand g/m2/year. This stability of the MAR characterized both loess-forming intervals in this part of Europe.
Źródło:
Geological Quarterly; 2007, 51, 2; 193-202
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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