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321.
Żaneta Polkowska Mieczysław Sobik Marek Błaś Kamila Klimaszewska Barbara Walna Jacek Namieśnik 《Journal of Atmospheric Chemistry》2009,62(1):5-30
Hoarfrost and rime analysis was based on the collection of samples between 2003 and 2006 from 8 sites, which represent both
lowland (northern) and mountainous (southern) parts of Poland. On the other hand 4 of these sites belong to “urban” and 4
to “rural” category. pH, conductivity, SO42−, NO3−, Cl−, H+, NH4+, Ca2+, Mg2+, Na+, K+ have been determined in order to study the chemistry of hoarfrost and rime. Higher total inorganic ionic content (TIC) in
hoarfrost and rime (2.46 meq·l−1 and 1.23 meq·l−1 respectively) was observed when compared with precipitation (0.37 meq·l−1). Large variability of TIC and chemical composition of individual samples were typical at each of the measurement sites depending
on emission patterns, atmospheric conditions and local terrain topography. Higher concentrations of both hoarfrost and rime
occurred in southern (mountainous) rather than in northern (lowland) part of Poland which can be explained by worse pollutant
dispersion conditions in the south. The surprisingly low hoarfrost concentrations in urban coastal stations in the area of
the Bay of Gdansk were attributed to the cleaning effect of nocturnal breeze-type circulation, best pronounced in cool part
of the year. Due to relatively high pollutant concentration and long duration, hoarfrost and rime are at least significant
factors in environmental processes in different ecosystems in Poland. 相似文献
322.
Sensitivity of the multiannual thermal dynamics of a deep pre‐alpine lake to climatic change 下载免费PDF全文
The study of the multiannual thermal dynamics of Lake Iseo, a deep lake in the Italian pre‐alpine area, is presented. Interflow was found to be the dominant river entrance mode, suggesting future susceptibility of the lake thermal structure to the overall effects of climate change expected in the upstream alpine watershed. A lake model employed the results of a long‐term hydrologic model to simulate the effects of a climate change scenario on the lake's thermal evolution for the period 2012–2050. The model predicts an overall average increase in the lake water temperature of 0.012 °C/year and a reinforced Schmidt thermal stability of the water column in the winter up to 800 J/m2. Both these effects may further hinder the deep circulation process, which is vital for the oxygenation of deep water. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
323.
Mass occurrence of benthic coccoid cyanobacteria and their role in the production of Neoarchean carbonates of South Africa 总被引:1,自引:0,他引:1
Jzef Kazmierczak Wladyslaw Altermann Barbara Kremer Stephan Kempe Patrick G. Eriksson 《Precambrian Research》2009,173(1-4):79
The sparse Archean fossil record is based almost entirely on carbonaceous remnants of microorganisms cellularly preserved due to their early post-mortem silicification. Hitherto as an exception, sedimentary carbonate rocks from the Neoarchean Nauga Formation of South Africa contain calcified microbial mats composed of microbiota closely resembling modern benthic colonial cyanobacteria (Chroococcales and Pleurocapsales). Their remains, visible under the scanning electron microscope (SEM) after etching of polished rock samples, comprise capsular envelopes, mucilage sheaths, and groups of cells mineralized by calcium carbonate with an admixture of Al–K–Mg–Fe silicates. The capsular organization of the mucilaginous sheaths surrounding individual cells and cell clusters forming colonies and the mode of mineralization are the characteristic common features of the Neoarchean microbiota described and their modern analogues. The new findings indicate massive production of calcium carbonates by benthic coccoid cyanobacteria in the Neoarchean, and offer a solution to the problem of the origin of Archean carbonate platforms, stromatolites and microbial reefs. 相似文献
324.
Tim Denham Kale Sniderman Krystyna M. Saunders Barbara Winsborough Alain Pierret 《Geoarchaeology》2009,24(6):715-742
Contiguous multi‐proxy analyses (X‐radiography, diatom, pollen, and microcharcoal) have been conducted on the fills of early, mid‐, and mid‐late Holocene features at Kuk Swamp, Upper Wahgi Valley, Papua New Guinea. The features are associated with key periods of archaeological interest: plant exploitation (ca. 10,000 cal yr B.P.), earliest cultivation (6950–6440 cal yr B.P.), and earliest ditches (ca. 4000 cal yr B.P.). The analyses are designed to clarify uncertainties regarding the reliability and association of different samples within feature fills for the interpretation of human activities on the wetland in the past. Methodologically, these investigations have clarified site formation processes, including pedogenesis within feature fills, which enable a better determination of archaeological associations for different samples within those fills. Substantively, the results provide higher resolution interpretations of paleoenvironments and past human activities on the wetland margin. © 2009 Wiley Periodicals, Inc. 相似文献
325.
Salvatore Giammanco Barbara Justin Natalija Speh Marta Veder 《Environmental Geology》2009,57(1):75-89
The complex geochemical interactions in the groundwater of the industrial area of Šalek Valley (Slovenia) between natural
and anthropogenic fluids were studied by means of major (Ca, Mg, Na, K, HCO3
−, Cl− and SO4
2−) and trace elements’ (As , Cd, Cu, Pb, Zn, Hg, Se and V) abundances, geochemical classification and statistical analysis
of data. Cation abundances indicate mixing between a dolomitic end-member and an evaporitic or geothermal end-member. Anion
abundances indicate mixing between bicarbonate waters and either sulphate-enriched waters (suggesting hydrothermalism) or
chlorine-rich waters. Principal component analysis (PCA) allowed the extraction of seven factors, which describe, respectively:
water–rock interaction mainly on dolomitic rocks; redox conditions of water; Cd–Zn enrichment in chlorine-rich waters (probably
from industrial wastes); hydrothermal conditions in waters close to major faults; Pb and Cu pollution; V and K enrichments,
indicating their common organic source; the role of partial pressure of CO2 dissolved in water, which is highest in three wells with bubbling gases. Average underground discharge rates of solutes from
the Valley range between 0.09 t/a (V) and 1.8 × 104 t/a (HCO3
−) and indicate how natural fluids can significantly contribute to the levels of elements in the environment, in addition to
the amount of elements released by human activities. 相似文献
326.
Rybak-Ostrowska Barbara Konon Andrzej Domonik Andrzej Poszytek Anna Uroda Joanna 《International Journal of Earth Sciences》2017,106(6):1863-1888
International Journal of Earth Sciences - We investigated exhumed damage zones of dextral strike-slip faults dissecting the south-western part of the Mesozoic cover of the Late Palaeozoic Holy... 相似文献
327.
Barbara Pfeil Buttenfield 《The Professional geographer》1986,38(3):238-246
The mental images on which an individual bases spatial decisions are often distorted versions of real-world geography. Distortion in these images is studied by extracting paired distance estimates and by requesting a sketch of a place drawn from memory. Reliance upon either technique to elicit large-scale spatial information assumes that distortion in the congnitive map is not introduced by the technique (sketching or configuration) used to construct it. Both techniques have been used in this study to produce cognitive maps for a common set of landmarks in Seattle. Map distortions are analyzed and compared to determine that significant differences result from the technique used. 相似文献
328.
329.
An ephemeris has been obtained for Explorer 28 (IMP 3) which agrees well with 2 years of radio observations and with SAO observations a year later. This ephemeris is generated over the 3 year lifetime by a numerical integration method utilizing a set of initial conditions, at launch and without requiring further differential correction. Because highly eccentric orbits are difficult to compute with acceptable accuracy and because a long continuous arc has been obtained which compares with actual data to a known precision, this ephemeris may be used as a standard for computing highly eccentric orbits in the Earth-Moon system.Orbit improvement was used to obtain the initial conditions which generated the ephemeris. This improvement was based on correcting the energy by adjusting the semimajor axis to match computed times of perigee passage with the observed. This procedure may generate errors in semimajor axis to compensate for model errors in the energy; however this compensation error is also implicit in orbit determination itself. 相似文献
330.