A high-resolution diatom-inferred palaeoconductivity and lake level record of the Aral Sea for the last 1600 yr   总被引：1，自引：0，他引：1  

Patrick Austin  Anson Mackay  Olga Palagushkina  Melanie Leng   《Quaternary Research》2007,67(3):383-393

Formerly the world's fourth largest lake by area, the Aral Sea is presently undergoing extreme desiccation due to large-scale irrigation strategies implemented in the Soviet era. As part of the INTAS-funded CLIMAN project into Holocene climatic variability and the evolution of human settlement in the Aral Sea basin, fossil diatom assemblages contained within a sediment core obtained from the Aral Sea have been applied to a diatom-based inference model of conductivity (r² = 0.767, RMSEP = 0.469 log₁₀ μS cm^− 1). This has provided a high-resolution record of conductivity and lake level change over the last ca. 1600 yr. Three severe episodes of lake level regression are indicated at ca. AD 400, AD 1195–1355 and ca. AD 1780 to the present day. The first two regressions may be linked to the natural diversion of the Amu Darya away from the Aral Sea and the failure of cyclones formed in the Mediterranean to penetrate more continental regions. Human activity, however, and in particular the destruction of irrigation facilities are synchronous with these early regressions and contributed to the severity of the observed low stands.  相似文献   

Geochemical Baselines of Nickel and Chromium in Various Surficial Materials in the Barents Region, NW Russia and Finland     

Reijo Salminen  Igor Bogatyrev  Victor Chekushin  Sergey P. Glavatskikh  Virgilija Gregorauskiene  Heikki Niskavaara  Lubov Selenok  Markku Tenhola  Olga Tomilina 《Geostandards and Geoanalytical Research》2004,28(2):333-341

The geochemical baselines of nickel and chromium were studied from the data produced by the Barents Ecogeochemistry project, a large international regional geochemical mapping exercise. The project surveyed major and trace element distributions in stream water, organic and mineralogically-modified soil horizons, and terrestrial moss in the northwestern part of Russia and in Finland. Other materials were collected during the pilot phase and later from thirty special sites. The results on respective materials by XRF, ICP-MS and ICP-AES showed that both geological and anthropogenic factors have an influence on the geochemical baseline concentrations of Ni and Cr in organic soil and stream water. The main explanation of the observed distribution patterns in terrestrial moss is human activity, but geological factors can also affect the baselines. The variation of geochemical baselines in the mineral-rich soil horizon depends only on variations in bedrock. The mineralogy of samples mainly controls the leachability properties of soil samples.  相似文献   

The amethyst-citrine dichromatism in quartz and its origin     

Vladimir S. Balitsky  Olga V. Balitskaya 《Physics and Chemistry of Minerals》1986,13(6):415-421

The occurrence of the amethyst-citrine dichromatism in natural and mainly synthetic quartz crystals was studied as a function of their growth conditions. It has been found experimentally that the origin of the coloration is related to the variable dependence of the incorporation of the amethyst- and citrine-producing impurities on the crystallographic direction and growth rates of the faces and also to the effect the charge compensators have on the thermal stability of the amethyst color centers.  相似文献   

Foreword     

Olga Gritsai  Herman van der Wusten 《GeoJournal》1997,41(4):291-292

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Petrological, organic geochemical and geochemical characteristics of coal from the Soko mine, Serbia   总被引：1，自引：1，他引：0  

Dragana ivoti&#x;  Herman Wehner  Olga Cvetkovi&#x;  Branimir Jovan i&#x;evi&#x;  Ivan Greti&#x;  Georg Scheeder  Angelika Vidal  Aleksandra &#x;ajnovi&#x;  Marko Ercegovac  Vladimir Simi&#x; 《International Journal of Coal Geology》2008,73(3-4):285-306

A petrological, organic geochemical and geochemical study was performed on coal samples from the Soko Mine, Soko Banja basin, Serbia. Ten coal and two carbonaceous clay samples were collected from fresh, working faces in the underground brown coal mine from different parts of the main coal seam. The Lower Miocene, low-rank coal of the Soko Mine is a typical humic coal with huminite concentrations of up to 76.2 vol.%, liptinite less than 14 vol.% and inertinite less than 11 vol.%. Ulminite is the most abundant maceral with variable amounts of densinite and clay minerals. Sporinite and resinite are the most common macerals of the liptinite group. Inertodetrinite is the most abundant maceral of the inertinite group. The mineral-bituminous groundmass identified in some coal samples, and carbonaceous marly clay, indicate sub-aquatic origin and strong bacterial decomposition. The mean random huminite reflectance (ulminite B) for the main coal seam is 0.40 ± 0.05% Rr, which is typical for an immature to early mature stage of organic matter.The extract yields from the coal of the Soko Banja basin ranges from 9413 to 14,096 ppm, in which alkanes constituted 1.0–20.1%, aromatics 1.3–14.7%, asphaltenes 28.1–76.2% and resins 20.2–43.5%. The saturated hydrocarbon fractions included n-C₁₅ to n-C₃₂, with an odd carbon number that predominate in almost all the samples. The contents of n-C₂₇ and n-C₂₉ alkanes are extremely high in some samples, as a contribution of epicuticular waxes from higher plants. Acyclic isoprenoid hydrocarbons are minor constituents in the aliphatic fraction, and the pristane/phytane (Pr/Ph) ratio varies between 0.56 and 3.13, which implies anaerobic to oxic conditions during sedimentation. The most abundant diterpanes were abietane, dehydroabietane and 16α(H)-phyllocladane. In samples from the upper part of the coal seam, diterpanes are the dominant constituents of the alkane fraction. Polycyclic alkanes of the triterpane type are important constituents of alkane fractions. The occurrence of ββ- and αβ-type hopanes from C₂₇ to C₃₁, but without C₂₈, is typical for the Soko Banja coals.The major and trace elements in the coal were analysed using X-ray fluorescence (XRF), and inductively coupled plasma-mass spectrometry (ICP-MS). In comparison with world lignites, using the geometric mean value, the coal from the Soko Banja Basin has a high content of strontium (306.953 mg/kg). Higher values than the world lignites were obtained for Mo (3.614 mg/kg), Ni (8.119 mg/kg), Se (0.884 mg/kg), U (2.642 mg/kg) and W (0.148 mg/kg). Correlation analysis shows inorganic affinity for almost all the major and trace elements, except for S, which has an organic affinity.  相似文献   

Identifying Critical Locations in a Spatial Network with Graph Theory   总被引：2，自引：0，他引：2  

Ur&#;ka Dem&#;ar  Olga &#;patenková  Kirsi Virrantaus 《Transactions in GIS》2008,12(1):61-82

Effective management of infrastructural networks in the case of a crisis requires a prior analysis of the vulnerability of spatial networks and identification of critical locations where an interdiction would cause damage and disruption. This article presents a mathematical method for modelling the vulnerability risk of network elements which can be used for identification of critical locations in a spatial network. The method combines dual graph modelling with connectivity analysis and topological measures and has been tested on the street network of the Helsinki Metropolitan Area in Finland. Based on the results of this test the vulnerability risk of the network elements was experimentally defined. Further developments are currently under consideration for eventually developing a risk model not only for one but for a group of co‐located spatial networks.  相似文献   

MODIS-NDVI-based mapping of the length of the growing season in northern Fennoscandia     

Stein Rune Karlsen  Anne Tolvanen  Eero Kubin  Jarmo Poikolainen  Kjell Arild Høgda  Bernt Johansen  Fiona S. Danks  Paul Aspholm  Frans Emil Wielgolaski  Olga Makarova 《International Journal of Applied Earth Observation and Geoinformation》2008

Northern Fennoscandia is an ecologically heterogeneous region in the arctic/alpine-boreal transition area. Phenology data on birch from 13 stations and 16-day MODIS-NDVI composite satellite data with 250 m resolution for the period 2000 to 2006 were used to map the growing season. A new combined pixel-specific NDVI threshold and decision rule-based mapping method was developed to determine the onset and end of the growing season. A moderately high correlation was found between NDVI data and birch phenology data. The earliest onset of the growing season is found in the narrow strip of lowland between the mountains and the sea along the coast of northern Norway. The onset follows a clear gradient from lowland to mountain corresponding to the decreasing temperature gradient. In autumn, the yellowing of the vegetation shows a more heterogeneous pattern. The length of the growing season is between 100 and 130 days in 55% of the study area.  相似文献   

Russian human geography in the 'wonderland' of globalization     

Olga Gritsai 《GeoJournal》1998,45(1-2):77-83

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State of the environment of urban and mining areas in the Selenga Transboundary River Basin (Mongolia Russia)     

Nikolay Kasimov  Natalia Kosheleva  Petr Gunin  Ilya Korlyakov  Olga Sorokina  Ivan Timofeev 《Environmental Earth Sciences》2016,75(18):1283

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Confronting the social debate: A study of the distribution of Russian recreational properties in Eastern Finland     

Olga Hannonen  Olli Lehtonen  Maija Toivakka 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(2):95-111

Transborder property ownership is a growing trend in different parts of the world. In Finland, Russians make up the biggest group of foreign buyers. The article examines Russian recreational property purchases in Eastern Finland, where South Savo Region is subject to the heaviest flow of Russian purchasers. Russian purchases of second homes have been the subject of a broad social debate dominated by negative attitudes towards the phenomenon. Fears of place change and displacement have been among the main concerns. The authors reveal how arguments presented in the social debate on Russian ownership correspond to the distribution of Russian properties in South Savo. Statistics for the period 2003–2012 and GIS methods were used to analyse the distribution and density of Russian recreational properties in the region. Statistical modelling uncovered some factors that affected the location of the properties. The findings indicate that the arguments presented within the social debate have only partially derived from the distribution patterns of Russian properties. The authors conclude that a combination of factors, including distances from the border and services as well as preferences for waterside locations, have influenced the choice of location of Russian properties and led to concentrations in certain areas.  相似文献