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41.
Theoretical and Applied Climatology - The aim of the study is the assessment and analysis of the variability of human-bioclimatic conditions in southern part of Warsaw, depending on the atmospheric... 相似文献
42.
Jacek Kozak Christine Estreguil Katarzyna Ostapowicz 《International Journal of Applied Earth Observation and Geoinformation》2008
The aim of the study was to elaborate a methodology for forest mapping based on high resolution satellite data, relevant for reporting on forest cover and spatial pattern changes in Europe. The Carpathians were selected as a case study area and mapped using 24 Landsat scenes, processed independently with a supervised approach combining image segmentation, knowledge-based rules to extract a training set and the maximum likelihood decision rule. Validation was done with available very high resolution imagery. Overall accuracies per scene ranged from 93 to 96%. The labelling disagreement in overlapping areas of adjacent scenes was 6.8% on average. 相似文献
43.
Kathrin?FassmerEmail author Iwona?Klonowska Katarzyna?Walczak Barbro?Andersson Nikolaus?Froitzheim Jaros?aw?Majka Raúl?O.?C.?Fonseca Carsten?Münker Marian?Janák Martin?Whitehouse 《Contributions to Mineralogy and Petrology》2017,172(11-12):103
The Seve Nappe Complex of the Scandinavian Caledonides is thought to be derived from the distal passive margin of Baltica which collided with Laurentia in the Scandian Phase of the Caledonian Orogeny at 430–400 Ma. Parts of the Seve Nappe Complex were affected by pre-Scandian high- and ultrahigh-pressure metamorphism, in a tectonic framework that is still unclear, partly due to uncertainties about the exact timing. Previous age determinations yielded between ~ 505 and ~ 446 Ma, with a general trend of older ages in the North (Norrbotten) than in the South (Jämtland). New age determinations were performed on eclogite and garnet–phengite gneiss at Tjeliken in northern Jämtland. Thermodynamic modelling yielded peak metamorphic conditions of 25–27 kbar/680–760 °C for the garnet–phengite gneiss, similar to published peak metamorphic conditions of the eclogite (25–26 kbar/650–700 °C). Metamorphic rims of zircons from the garnet–phengite gneiss were dated using secondary ion mass spectrometry and yielded a concordia age of 458.9 ± 2.5 Ma. Lu–Hf garnet-whole rock dating yielded 458 ± 1.0 Ma for the eclogite. Garnet in the eclogite shows prograde major-element zoning and concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types, coinciding with published Sm–Nd ages from the eclogite, confirm subduction of the Seve Nappe Complex in Northern Jämtland during the Middle Ordovician in a fast subduction–exhumation cycle. 相似文献
44.
The paper analyses the concentrations of total phosphorus and its forms in sediments from the Gulf of Gdańsk on the basis of studies conducted at 25 sampling sites in 2001–05. The phosphorus speciation analysis was performed by sequential extraction. The extensive spatial variability of Ptot concentrations and speciation was found to be dependent on the physicochemical properties of the sediments, the oxygen conditions in the water and sediments, and the depth of the water column above the sediment surface. In the coastal zone, the sedimentation of riverine suspended matter and the sorption and chemisorption processes exert a considerable influence on P speciation. Over 70% of variation of total phosphorus concentration in sediments in the Gulf of Gdańsk could be explained by changes of proportion of fine fraction of sediments (grain size <0.0625 mm). Maximum Ptot concentrations were recorded in clays and silts in the deep water, stratified part of the Gulf of Gdańsk. In the coastal zone, where sandy sediments are dominant, phosphorus concentrations were much lower; this was due to the considerable dynamics of the bottom water and intensive sea floor transport. Ptot concentrations in the Gulf of Gdańsk sediments ranged from 1.75 to 957.17 μmol g−1 d.w. Of all the forms of phosphorus, the highest concentrations were found for organic phosphorus (Org-P). Of its inorganic forms, the highest concentrations were of phosphorus bound to clay minerals and aluminium oxides (NaOH-P), the lowest ones were of loosely bound phosphorus (NaCl-P). On the basis of determinations of total phosphorus concentrations in sediments of a given type and the available data on the seabed areas covered by particular sediment types in the Gulf of Gdańsk, the mass of total phosphorus in the surficial sediment layer (0–2 cm) was estimated at ca. 15.6×103 tonnes. 相似文献
45.
46.
The toxicity of sediments in the Gulf of Gdansk is analyzed in relation to the chemical composition of interstitial and near‐bottom waters, and sediment properties. The toxicity of sediments, pore waters and saline elutriates is determined by using the Microtox® test based on changes in light production of the luminescent bacteria Vibrio fischeri. The results indicate considerable toxicity in the majority of examined sediments. Since the sediment elutriates and pore waters are toxic in some cases, the total toxicity of the sediments is likely to be due to both sediment‐bound and water soluble substances. The sediment toxicity is related to the percentage contribution of the fine fraction of sediments. A significant correlation between the toxicity of the sediments and the black carbon content implies anthropogenic contamination. The toxicity of the sediments is seen to increase with the increase of hydrogen sulfide concentration in pore waters. The ammonia in pore waters was found not to be responsible for the toxicity of the sediments. 相似文献
47.
Tong Bao Xuesong Zhang Katarzyna S. Walczyńska Bo Wang Jes Rust 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(2):247-256
Within this study the subfamily Praemordellinae is reviewed and the holotype of Praemordella martynovi Scegoleva-Barovskaja, 1929 is re-described. The genera Cretanaspis Huang and Yang, 1999, Mirimordella Liu et al., 2007, Bellimordella Liu et al., 2008 and Wuhua Wang and Zhang, 2011 is attributed to Praemordellinae. One new species, Wuhua peregrina sp. nov., is erected based on two well-preserved specimens from the Middle Jurassic Daohugou Biota (Inner Mongolia, China). The morphological characters of Praemordellinae are given and a key to genera of Praemordellinae is presented. Praemordellinae is closely related to extant Mordellidae in having humpbacked body, strongly deflexed head, filiform antennae and pectinate tarsal claws, but it is differing in that the pygidium absent and hind femora not well developed. It is also similar to Ripiphoridae in having a convex body and simple tarsi, but differs Ripiphoridae in having filiform antennae. Praemordellinae is probably a stem group including the ancestor of Mordellidae and Ripiphoridae. Also, within this paper, the fossil record of Mordellidae is summarized. 相似文献
48.
Analysis of data characterizing the chemical composition of atmospheric precipitation was presented, with an emphasis on components responsible for neutralization of rain acidity. For this purpose, chemometric methods were applied. Based on a principal component analysis (PCA) a strong correlation between precipitation pH and potassium and ammonium ions in the heating period (October–March) and potassium and sodium ions in the non‐heating period (April–September) was observed. Additionally, a classification of eight variables, i.e., Na+, K+, Mg2+, Ca2+, , , Cl?, and according to their similarities was made using a cluster analysis. Based on this study, two ions, potassium and ammonium, together with the pH value were classified into one group (cluster) in the heating period while in the non‐heating period ions of potassium and sodium were clustered together with the pH. The results of the cluster analysis indicated that the selected ions contributed the most to the neutralization of the atmospheric precipitation acidity. This relationship was confirmed by a discriminant analysis in which potassium and ammonium ions were selected as components of the highest potential for precipitation classification according to its acidity degree. The relationship between the precipitation pH and the number of non‐precipitation days preceding the precipitation was also analyzed. It was found that although the observed an increase of the pH value was not very high, nevertheless, the effect of the duration of the period preceding the precipitation on the pH value recorded on the day of the precipitation occurrence was quite evident. 相似文献
49.
In order to simulate evolution of a large-scale magnetic field in a barred galaxy possessing a gaseous halo we apply a three-dimensional
(3D) MHD numerical model. We solve a induction equation using a time-dependent velocity field of molecular gas resulting from
self-consistent 3D N-body simulations of a galactic disk. The gaseous halo rotates differentially co-rotating with the disk.
In our model we introduce the dynamo process causing the amplification of the magnetic field as well as the formation of field
structures high above the galactic disk. The simulated magnetic fields are used to construct the models of a high-frequency
(Faraday rotation-free) polarized radio emission that accounts for effects of projection and limited resolution, and is thus
suitable for direct comparison with observations. We found that the resultant magnetic field correctly reproduces the observed
structures of polarization B-vectors, forming coherent patterns well aligned with spiral arms and with the bar. The process
initializing a wave-like behavior of the magnetic field, which efficiently forms magnetic maxima between the spiral arms,
is demonstrated.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
50.