City size distributions and metropolisation     

Denise Pumain  François Moriconi-Ebrard 《GeoJournal》1997,43(4):307-314

Many controversial questions about the shape and evolution of city size distributions can be solved if reliable, large and comparable set of data are used for several countries. We provide new empirical evidence by using the large data base Geopolis, which has strictly comparable figures for all towns and cities of the world over 10,000 inhabitants between 1950 and 1990. A Pareto model is used for identifying as metropolises one or a few large cities for each national urban system. From those data, two empirical power laws are established, linking the size of the metropolises to the size of their national urban system. The first is a transversal law: for a set of countries at a given date, the share of population concentrated in metropolises tends to decrease when larger countries are considered. The second law, which is longitudinal, shows that metropolises in the past have grown in a systematic way more rapidly than the rest of their urban system, invalidating Gibrat's urban growth model. Such empirical regularities could help for predicting the future of nowadays observed metropolisation trends.  相似文献   

Long-term TNT and DNT contamination: 1-D modeling of natural attenuation in the vadose zone: case study,Portugal     

Helena?I.?F.?AmaralEmail author  Ana Claúdia?Gama  Cláudia?Gon?alves  Judite?Fernandes  Maria?Jo?o?Batista  Manuela?Abreu 《Environmental Earth Sciences》2016,75(1):89

The vadose zone of a trinitrotoluene (TNT) and dinitrotoluene (DNT) contaminated site was investigated to assess the mobility of those explosives under natural conditions. Located in the left margin of the River Tejo Basin, Portugal, the site is located on unconsolidated sediments. Wastewaters associated with the 50-year explosives production were disposed in excavated ponds, from where water would infiltrate and pollute the unsaturated and saturated parts of the local aquifers. Two boreholes were drilled to 9 m depth in such a former waste pond to investigate the contaminant’s fate in the vadose zone. Sediment samples were taken every 1–2 m for analysis of the poly-nitroaromatics (p-NACs) and organic volatile compounds, pH, organic carbon content, cation exchange capacity and grain size analysis. The main contaminant was TNT representing >70 % of the total p-NACs concentration that peaked approximately 7 mg/kg in one borehole, even if the median in both boreholes was of ~1 mg/kg. DNT was 4–30 % of the total p-NACs and nitrotoluene (NT), up to 5 %. No other (volatile) organic compound was detected. The predominance of TNT as the main contaminant implies that any natural mass reduction has been inefficient to clean the site. Several 1-D model simulations of p-NACs cleaning of the vadose zone under natural conditions indicated that the most probable scenario of combined advection and partitioning will only remove TNT after 10’s of years, whereas DNT and NT will hardly be removed. Such low concentrations and long times for the p-NACs removal, suggest that by now those compounds have been washed-out to a level below standard limits.  相似文献   

Arabian plate: lithosphere dynamics,sedimentary basins,and geo-resources     

Sami Khomsi  Mansour A. M. Al Garni  Ammar Amin  François Roure 《Arabian Journal of Geosciences》2016,9(11):576

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Application of Chebyshev theorem to data preparation in landslide susceptibility mapping studies:an example from Yenice(Karabük,Turkey) region     

Murat Ercanoglu  Gülseren Dağdelenler  Erman Özsayin  Tolga Alkevlı  Harun Sönmez  N. Nur Özyurt  Burcu Kahraman  İbrahim Uçar  Sinem Çetınkaya 《山地科学学报》2016,13(11):1923-1940

Landslide database construction is one of the most crucial stages of the landslide susceptibility mapping studies. Although there are many techniques for preparing landslide database in the literature, representative data selection from huge data sets is a challenging, and, to some extent, a subjective task. Thus, in order to produce reliable landslide susceptibility maps, data-driven, objective and representative database construction is a very important stage for these maps. This study mainly focuses on a landslide database construction task. In this study, it was aimed at building a representative landslide database extraction approach by using Chebyshev theorem to evaluate landslide susceptibility in a landslide prone area in the Western Black Sea region of Turkey. The study area was divided into two different parts such as training (Basin 1) and testing areas (Basin 2). A total of nine parameters such as topographical elevation, slope, aspect, planar and profile curvatures, stream power index, distance to drainage, normalized difference vegetation index and topographical wetness index were used in the study. Next, frequency distributions of the considered parameters in both landslide and nonlandslide areas were extracted using different sampling strategies, and a total of nine different landslide databases were obtained. Of these, eight databases were gathered by the methodology proposed by this study based on different standard deviations and algebraic multiplication of raster parameter maps. To evaluate landslide susceptibility, Artificial Neural Network method was used in the study area considering the different landslide and nonlandslide data. Finally, to assess the performances of the so-produced landslide susceptibility maps based on nine data sets, Area Under Curve (AUC) approach was implemented both in Basin 1 and Basin 2. The best performances (the greatest AUC values) were gathered by the landslide susceptibility map produced by two standard deviation database extracted by the Chebyshev theorem, as 0.873 and 0.761, respectively. Results revealed that the methodology proposed by this study is a powerful and objective approach in landslide susceptibility mapping.  相似文献   

Global risks of Bedellia somnulentella (Lepidoptera: Bedelliidae) invasion: a modeling exercise using a mechanistic model,CLIMEX     

dos Santos  Marinalva Martins  da Silva  Ricardo Siqueira  Soares  Marcus Alvarenga  Lopes  Érika Manuela Gonçalves  Shabani  Farzin 《Theoretical and Applied Climatology》2022,149(1-2):401-411

Theoretical and Applied Climatology - This study aimed to identify the global risk of invasion and establishment of Bedellia somnulentella, a pest of the sweet potato crop, for the present and...  相似文献   

Applications of innovative polygonal trend analyses to precipitation series of Eastern Black Sea Basin,Turkey     

Hırca  Tuğçe  Eryılmaz Türkkan  Gökçen  Niazkar  Majid 《Theoretical and Applied Climatology》2022,147(1-2):651-667

Theoretical and Applied Climatology - Examining historical variations of hydroclimatic variables can provide crucial information about changes of water resources in a water cycle. In this study,...  相似文献   

Geochemical characteristics of Kırka (Sarıkaya) borate deposit,northwestern Anatolia,Turkey     

İ Koçak  Ş Koç 《Journal of Earth System Science》2016,125(1):147-164

The K?rka borate deposit was deposited in a Miocene lacustrine basin which is closely associated with volcanic activity which lasted from Paleogene to the beginning of Quaternary. Borate mineralization alternates with claystone, mudstone, tuff and fine-layered limestone and mostly shows a lenticular structure. The mineral paragenesis is composed of borax, tincalconite, ulexite, kurnakovite, probertite, tunellite, colemanite, dolomite, smectite group minerals, illite and some firstly reported minerals for the K?rka deposit including hydrochloroborite, brianroulstonite, hilgardite-4M and searlesite minerals. In comparison to average values of earth crust, concentrations of Cs, Sr, Li, As and Se were significantly enriched with respective rates of 21, 15, 14, 3 and 188 folds. Regarding KY, KS1 and KS2 locations, there are differences in both element abundances and their geochemical tendencies which are attributed to variations in discharge regime and physico-chemical conditions of the depositional environment. Independent behaviour of B₂O₃ might indicate that boron is not associated with clays and carbonates and, therefore, most part of boron must be derived from volcanic activity (hydrothermal solutions, gases). REE data indicate that the K?rka borate deposit was formed in a sedimentary environment where highly alkaline (high pH) hydrothermal solutions also took part in borate precipitation process.  相似文献   

Response of hurricane-type vortices to global warming as simulated by ARPEGE-Climat at high resolution   总被引：1，自引：0，他引：1  

Fabrice Chauvin  Jean-François Royer  Michel Déqué 《Climate Dynamics》2006,27(4):377-399

Atlantic hurricanes and their sensitivity to anthropogenic warming are investigated using very high (0.5°×0.5° over the Atlantic domain) resolution global simulations. The ARPEGE-Climat variable resolution grid demonstrates its usefulness in regional climate studies since resolution can be multiplied by a factor of 2.5 over the domain of interest compared to a uniform grid, for a similar computer cost. The question of hurricane characteristics dependence on anthropogenic warming is tackled trough the implementation of a tracking method. Changes in the total number, as well as locations, of hurricanes appear to depend more on sea surface temperature (SST) spatial patterns anomaly than Atlantic mean intensity, essentially through the change in large scale vertical wind shear. A uniform SST anomaly forcing produces increased and eastward shifted systems while a spatially contrasted anomaly leads to a decrease. Comparison between cyclogenesis density calculated from tracking or large scale combined variables (as a modified Gray parameter) brings some confidence in the use of the latter to investigate low resolution simulations. Mean hurricane dynamical characteristics are weakly changed by the warming but precipitation core and latent heat flux are enhanced in all scenarios.  相似文献   

Titanite and zircon fission-track dating resolves successive igneous episodes in the formation of the composite Kaçkar batholith in the Turkish eastern Pontides     

D. Boztuğ  R. Jonckheere  G. A. Wagner  A. I. Erçin  Z. Yeğingil 《International Journal of Earth Sciences》2007,96(5):875-886

The Kaçkar batholith in the Turkish eastern Pontides comprises several intrusive units with distinctive textural, mineralogical and geochemical characteristics. Their titanite and zircon fission-track ages confirm that the different lithodem units result from consecutive igneous episodes, establish their emplacement sequence and, together with geochemical data, help to relate them to their geodynamic context. The Çaml?kaya granitoid (112.4 ± 1.6 Ma) was emplaced during an immature-arc magmatic episode of early Cretaceous age. The S?rtyayla (57.1 ± 1.2 Ma) and Marselevat (52.9 ± 1.3 Ma) granitoids are late products of a late-Palaeocene mature-arc episode. The Ayder granitoid (46.4 ± 1.0 Ma) is the result of middle- to late-Eocene post-collisional magmatism related to slab break-off. The Halkal?ta? quartz diorite (43.7 ± 2.3 Ma) and the Güllüba? monzonite (38.1 ± 0.9 Ma) document a middle- to late-Eocene episode related to post-collisional extension. The data reveal the advantages of dense sampling, spanning a maximum range of elevations. Apart from the increased precision on the mean, redundant sampling allows to shift the basis for interpretation from a priori assumptions to a posteriori numerical criteria when using geochronometers with low to moderate closure temperatures, including apatite, titanite and zircon fission-tracks but also K–Ar (Ar–Ar) biotite, muscovite and K-feldspar.  相似文献   

An assessment of changes in properties of steppe kurgan paleosoils in relation to prevailing climates over recent millennia     

Tatiana E. Khomutova  Tatiana S. Demkina  Alexander V. Borisov  Natalia N. Kashirskaya  Maxim V. Yeltsov  Vitaly A. Demkin 《Quaternary Research》2007,67(3):328-336

Comparative analysis of morphological and chemical properties of the soil chronosequence on Kastanozems soils in the steppe zone of the Russian Plain, which included paleosoils buried beneath kurgans erected ca. 2000 BC, AD 50, AD 200, and AD 1250 was performed to reconstruct the paleoenvironmental conditions in this archeologically important region. Paleoenvironmental dynamics were traced using the state of microbial communities of paleo and modern soils (including the dynamics of total and glucose-reactive biomass, and the abundance of microorganisms grown on selected media). We demonstrate that the share of the glucose-reactive microorganisms in the microbial community, the ecological–trophic structure, and oligotrophicity index might serve as indicators of the state of microbial communities and be used for paleoenvironmental reconstructions. The morphological–chemical and microbial properties confirm an arid period ca. 2000 BC, slightly wetter conditions ca. AD 50, and more humid conditions ca. AD 1250.  相似文献