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1.
Kaare L. Rasmussen Hans J. F. Olsen Raymond Gwozdz Evgeniy M. Kolesnikov 《Meteoritics & planetary science》2001,36(7):1001-1006
Abstract— Jull et al. propose an alternative interpretation of our depth vs. 14C data measured on a peat core from the central Tunguska impact site (Rasmussen et al., 1999). We find that the proposed alternative is untenable. 相似文献
2.
Rajmund DYBCZYNASKI Halina POLKOWSKA-MOTRENKO Zbigniew SAMCZYNASKI Zygmunt SZOPA 《Geostandards and Geoanalytical Research》1991,15(2):163-185
World-wide intercomparison runs has made possible the certification of two new Polish geological-environmental reference materials for multi-element trace analysis: Apatite Concentrate (CTA-AC-1) and Fine Fly Ash (CTA-FFA-1). "Recommended values' are established for 25 (CTA-AC-1) and 40 (CTA-FFA-1) elements respectively. In addition, "information values' are assigned for 12 elements in CTA-AC-1 and 10 elements in CTA-FFA-1. Our method of data evaluation has been further improved and a modified version of criteria for assigning recommended and information values is proposed. 相似文献
3.
Jacek?MajorowiczEmail author Jan??afanda Rajmund?Przybylak Gabriel?Wójcik 《Pure and Applied Geophysics》2004,161(2):351-363
Ground Surface Temperature (GST) history in Poland was derived from the inversion of temperature-depth profiles in over 20 wells. Temperature histories for the period 1500 A.D. through 1977 A.D. agree well with the instrumental record of the surface-air temperature available for the last two centuries. A statistical correlation of the reconstructed histories (from the well temperature data) with the instrumental record (air temperature) from the homogeneous Warsaw series is high (>0.8). Functional space inversion (FSI) of the temperature data with depth shows that beginning in the early 19th century, temperatures warmed by 0.9 ± 0.1°C following a long period of colder climate before. The last number could be a minimal as higher warming was calculated using a simple model based on surface temperature for the observational period (homogenized Warsaw surface temperature series, Lorenc, 2000) and POM (pre-observational mean; Harris and Chapman, 1998) of –1.53oC below the 1951–1980 mean temperature level. 相似文献
4.
Fortuniak Krzysztof Przybylak Rajmund Araźny Andrzej Pawlak Włodzimierz Wyszyński Przemysław 《Theoretical and Applied Climatology》2017,130(3-4):959-970
Maize is grown by millions of smallholder farmers in South Asia (SA) under diverse environments. The crop is grown in different seasons in a year with varying exposure to weather extremes, including high temperatures at critical growth stages which are expected to increase with climate change. This study assesses the impact of current and future heat stress on maize and the benefit of heat-tolerant varieties in SA. Annual mean maximum temperatures may increase by 1.4–1.8 °C in 2030 and 2.1–2.6 °C in 2050, with large monthly, seasonal, and spatial variations across SA. The extent of heat stressed areas in SA could increase by up to 12 % in 2030 and 21 % in 2050 relative to the baseline. The impact of heat stress and the benefit from heat-tolerant varieties vary with the level of temperature increase and planting season. At a regional scale, climate change would reduce rainfed maize yield by an average of 3.3–6.4 % in 2030 and 5.2–12.2 % in 2050 and irrigated yield by 3–8 % in 2030 and 5–14 % in 2050 if current varieties were grown under the future climate. Under projected climate, heat-tolerant varieties could minimize yield loss (relative to current maize varieties) by up to 36 and 93 % in 2030 and 33 and 86 % in 2050 under rainfed and irrigated conditions, respectively. Heat-tolerant maize varieties, therefore, have the potential to shield maize farmers from severe yield loss due to heat stress and help them adapt to climate change impacts. 相似文献
5.
Rajmund Gwozdz Hans J. Hansen Kaare L. Rasmussen 《Geostandards and Geoanalytical Research》2001,25(1):159-166
The collapse of a section of the cliff at Stevns Klint, Denmark in 1986 provided a unique opportunity to collect about 50 kg of Fish Clay representing the Cretaceous-Tertiary (K-T) boundary layer. In this paper, details of the preparation of this sample are presented, together with preliminary analytical results to support the development of this sample as a reference material, particularly for the determination of iridium and the other platinum-group elements in clays and sediments associated with K-T boundary studies and in other environmental samples collected to study the effects of automobile exhaust catalysts. 相似文献
6.
Lithium was analysed in 392 basalts and related igneous rocks from the North Atlantic Tertiary-Recent province using activation analysis and ?erenkov counting.Monotonous Li values of 5.5±2 ppm in NE Atlantic basalts define a low-Li geochemical province which has persisted for 60 million years, over 20° of latitude and regardless of basalt type and chemistry. This low-Li province and the increasing Li contents of ocean-ridge tholeiites into the S Atlantic are believed to monitor Li heterogeneity in the underlying mantle.Li, like Na, increases gently during the differentiation of several basalt series. No whole-rock coherence is observed between Li and Mg, K, Rb or Ca. Mantle phlogopite is considered to play an insignificant rôle in controlling the Li levels of NE Atlantic basalts. 相似文献
7.
Stephan A. Klapp Frieder Enzmann Peter Walz Thomas Huthwelker Jürgen Tuckermann J.-Oliver Schwarz Thomas Pape Edward T. Peltzer Rajmund Mokso David Wangner Federica Marone Michael Kersten Gerhard Bohrmann Werner F. Kuhs Marco Stampanoni Peter G. Brewer 《Geo-Marine Letters》2012,32(5-6):555-562
Despite much progress over the past years in fundamental gas hydrate research, frontiers to the unknown are the early beginning and early decomposition of gas hydrates in their natural, submarine environment: gas bubbles meeting ocean water and forming hydrate, and gas starting to escape from the surface of a hydrate grain. In this paper we report on both of these topics, and present three-dimensional microstructure results obtained by synchrotron radiation X-ray cryo-tomographic microscopy (SRXCTM). Hydrates can precipitate when hydrate-forming molecules such as methane exceed solubility, and combine with water within the gas hydrate stability zone. Here we show hydrate formation on surfaces of bubbles from different gas mixtures and seawater, based on underwater robotic in situ experiments in the deep Monterey Canyon, offshore California. Hydrate begins to form from the surrounding water on the bubble surfaces, and subsequently grows inward into the bubble, evidenced by distinct edges. Over time, the bubbles become smaller while gas is being incorporated into newly formed hydrate. In contrast, current understanding has been that hydrate decomposition starts on the outer surface of hydrate aggregates and grains. It is shown that in an early stage of decomposition, newly found tube structures connect well-preserved gas hydrate patches to areas that are dissociating, demonstrating how dissociating areas in a hydrate grain are linked through hydrate that is still intact and will likely decompose at a later stage. Figure
The boundaries of a gas hydrate grain: excepting for the matrix (transparent, not shown), one can see tubular structures, pores from decomposition, and bubbles. 相似文献
8.
Uranium is significantly enriched (up to two orders of magnitude) in the Danish Cretaceous-Tertiary boundary beds relative to the underand overlaying sediments. Both the predominant oxic and some anoxic deposits have a high uranium content. To investigate the geochemical behaviour of the element, a series of sections was analysed for uranium by means of the delayed-neutron counting technique. Uranium contents in the carbonate rocks from different parts of the Danish Sub-basin are generally low but show slight regional trends. Experiments that involve cold acid extractions suggest that uranium is associated with the non-carbonate residues. The uranium distribution with depth in the offshore drill core from the Central Graben area (North Sea) suggests that the element is associated with clay in the Danian part. Cretaceous-Tertiary boundary beds from Stevns Klint and other localities in the Danish sub-basin have anomalously high uranium contents compared with the values for chalk. Uranium is not correlated with iron, non-carbonate carbon or aluminium. The highest uranium values within boundary sections are not found in the lower part of the sections as is the case for iridium. The only boundary beds that show typical anoxic depositional affinity have a total uranium accumulation that is one order of magnitude lower than that found in the oxic sections. High amounts of uranium within Cretaceous-Tertiary boundary beds are suggested to be related to diagenetic processes such as compaction and dehydration. Uranium is thought not to cause the extinctions at the Cretaceous-Tertiary boundary because of the relatively low contents found at the actual extinction level. 相似文献
9.
Li was analysed by activation analysis in 363 whole-rock samples and 53 minerals from a 200 m drill core through aegirine lujavrite I, Ilímaussaq intrusion. The rocks are interpreted as cumulates and Li is dominantly located in the intercumulus material which is thought to represent the coexisting magma with 540 ppm: whole-rock contents generally range from 80–260 ppm Li and reflect variations in the amount of intercumulus material from 25–48 wt. %. The proportion of intercumulus material is lowest in the deeper parts of the drill core, in layers with a moderate density stratification resulting from showers of near-liquidus crystals and in compressed cumulates beneath a large naujaite xenolith from the roof. Intercumulus arfvedsonite with an average of 2200 ppm Li contains the bulk of Li in most samples, but nearly every sample contains Li (0–176 ppm) outside the rock-forming minerals (Li-ORFM) which was unlocated by conventional mineral separation. Li-ORFM formed during late-magmatic crystallization (a) from the final residues of intercumulus magma which crystallised as accessory Li-mica and alteration products and (b) during in situ zeolitization of arvedsonite which released Li. A later, more intense zeolitization released Li from the rocks of the drill core. Naujaite xenoliths contain 42–130 ppm Li, except where Li-metasomatised, and are associated with low Li values in adjacent lujavrites. Shearing of consolidated lujavrite allowed mobilization of the Li and its reprecipitation along narrow channels (< 10 cm). Li is not concentrated in late hydrothermal coatings. 相似文献
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