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991.
Spatial and temporal analysis of global seismological data 1964–2005 reveals a distinct teleseismic earthquake activity producing
a columnar-like formation in the continental wedge between the Krakatau volcano at the surface and the subducting slab of
the Indo-Australian plate. These earthquakes occur continuously in time, are in the body-wave (m
b) magnitude range 4.5–5.3 and in the depth range 1–100 km. The Krakatau earthquake cluster is vertical and elongated in the
azimuth N30°E, suggesting existence of a deep-rooted fault zone cutting the Sunda Strait in the SSW-NNE direction. Possible
continuation of the fault zone in the SW direction was activated by an intensive 2002/2003 aftershock sequence, elongated
in the azimuth of N55°E. Beneath the Krakatau earthquake cluster, an aseismic gap exists in the Wadati-Benioff zone of the
subducting plate at the depths 100–120 km. We interpret this aseismic gap as a consequence of partial melting inhibiting stress
concentration necessary to generate stronger earthquakes, whereas the numerous earthquakes observed in the overlying lithospheric
wedge beneath the volcano probably reflect magma ascent in the recent plumbing system of the Krakatau volcano. Focal depth
of the deepest events (~100 km) of the Krakatau cluster constrains the location of the primary magma generation to greater
depths. The ascending magmatic fluids stress fault segments within the Sunda Strait fault zone and change their friction parameters
inducing the observed tectonic earthquakes beneath Krakatau. 相似文献
992.
993.
S. A. Medina-Moreno Ph.D. D. Jiménez-Islas Ph.D. J. N. Gracida-Rodríguez Ph.D. M. Gutiérrez-Rojas I. J. Díaz-Ramírez Ph.D. 《International Journal of Environmental Science and Technology》2011,8(3):471-482
A mathematical model to predict the rhamnolipids production by Pseudomonas aeruginosa from oleic acid in a two phase liquid-liquid batch reaction system, was developed in this study. The model was based on two theoretical assumptions: 1) the convective oleic acid mass transfer is coupled to a bioreaction in the aqueous liquid bulk, and 2) the volume of the immiscible oleic acid drops and the saturation concentration at the interface are a function of rhamnolipids production. The model was able to accurately predict the experimental growth of the Pseudomonas aeruginosa strain, and the rhamnolipids production data with oleic acid as carbon source. This mathematical approach indicated a high correspondence between the saturation dimensionless profiles of oleic acid at the interface and the experimental profiles of surface tension difference. This modeling approach may constitute a useful tool in the design and scaling-up of bioreactors applied to the production of biosurfactants with immiscible carbon sources. 相似文献
994.
Comparison of quantitative petrographic, stable isotope and cathodoluminescence data for fingerprinting Czech marbles 总被引:1,自引:1,他引:0
Various marbles from both historic quarries and historical artefacts of the Czech Republic were examined in order to make determinations of their provenance. The methodology used was based upon a combination of petrographic image analysis (PIA) of thin sections, stable isotope geochemistry of carbonates, and cathodoluminescence. Multivariate statistical methods (i.e. cluster analysis and discriminant analysis) confirmed the geoscientific relevance of the marble’s different characteristics with a high degree of consistency as well as the enhanced significance of stable C and O isotopes in correlation with the petrographic data. The qualitative cathodoluminescence data provided a useful additional tool to help recognise the fingerprinting of marbles with similar petrographic and/or geochemical characteristics. 相似文献
995.
M. I. Carretero M. Pozo F. Ruiz J. Rodríguez Vidal L. M. Cáceres M. Abad J. M. Muñoz F. Gómez J. M. Campos M. L. González-Regalado M. Olías 《Environmental Earth Sciences》2011,64(5):1215-1223
The multidisciplinary analysis of core sediments from Doñana National Park, south Spain, permits to delimitate both the paleoenvironmental changes and the geochemical evolution of this area during the Holocene. In a first phase (10–6.5 kyr cal), this area was occupied by freshwater/brackish marshes with periodical alternation of dry periods and humid intervals. In a second phase, these marshes were inundated during the Flandrian transgression (~6.5 kyr cal), with the deposition of bioclastic sands. The third phase (6.5–3.6 kyr cal) is characterized by the transition to an old lagoon, with unpolluted, bottom sediments. The geochemical concentrations of these clayey sediments can be used as a geochemical background for present-day and future environmental evaluations of this area. In the following 600 years approximately, two tsunamis caused the partial infilling of this area with bioclastic, marine sediments. In the interval comprised between these two tsunamis, this lagoon was polluted with heavy metals derived from historical mining activities. This environmental contamination represents one of the oldest evidences of mining pollution in the world (>3 kyr cal BP). 相似文献
996.
The dominant factors affecting the development of weathering forms on the Prav?ice Rock Arch (PRA) (Bohemian Switzerland National Park, Czech Republic) are discussed, based on the in situ monitoring of weathering forms, as well as on laboratory studies of materials taken from this site. The in situ monitoring shows the progressive development of distinct weathering forms (delamination of case-hardened rock surfaces, cyclic efflorescence, and granular disintegration of exposed weakly cemented rock mass) in specific portions of the PRA, whose location is controlled by lithology, jointing/local hydrodynamics, and exposure to climatic factors. From the analysis of efflorescence, the dominance of sulphates is evident; particularly of gypsum and alums. However, the synergistic effects of the several salt species (that also include minor nitrates and chlorides) upon the mechanical disintegration of sandstone can be expected. 相似文献
997.
998.
999.
Chemistry of the Ferraria thermal water, S. Miguel Island, Azores: mixing and precipitation processes 总被引:1,自引:1,他引:0
Maria do Rosário Carvalho António Mateus Jo?o C. Nunes José M. Carvalho 《Environmental Earth Sciences》2011,64(2):539-547
The Ferraria thermal water emerges at the sea level in the Ferraria lava delta (western edge of S. Miguel Island, Azores)
with temperature of ca. 60°C and pH varying between 5.4 and 6.2. It is of sodium chloride type, resulting from ca. 50% seawater
mixing with an acid brackish, at ≈100°C, denoting the presence of significant CO2(g) and the progress of water–rock interactions in open system conditions. The thermal Na–Cl water is strongly enriched with
Sr and Mn and, comparatively, has low concentrations in Al, Fe and As. These elements are removed from the solution as critical
conditions for the formation of several neo-formed mineral phases are gradually attained. Thermodynamic equilibrium calculations
are consistent with this interpretation, showing that the thermal fluid can precipitate Fe3+-(hydr-)oxides, kaolinite and non-crystalline silica. Wells logging show fracture planes and pores fully/partly filled up
with polyphase botryoidal aggregates mostly composed of goethite + ferrihydrite and displaying variable adsorbed contents
of Si, P and As. These neo-formed phases result from the pristine fluid oxidation due to seawater mixing; its precipitation
is easily affected by pH and redox variations of the brackish, due to volcanic gases pressure alterations, and fluid pressure
or flow-velocity oscillation in the fractured aquifer. 相似文献
1000.
María Teresa Rodríguez-Salazar Ofelia Morton-Bermea Elizabeth Hernández-Álvarez Rufino Lozano Victor Tapia-Cruz 《Environmental Earth Sciences》2011,62(5):899-905
This research presents and discusses information concerning the spatial distribution of heavy metals (Pb, Cu, Zn, Ba, Co,
Cr, Ni and V) in the urban environments of Mexico City using geographical information system and statistical analysis. Superficial
soil samples (n = 146) were analyzed. The highest contamination indices were found in the north and center zone of the metropolitan area.
In contrast, the surrounding rural fields show a lower impact grade. The higher concentrations of Pb, Cu, Zn and Ba were observed
as being related to high vehicular traffic, nevertheless other elements such as Co, Cr, Ni and V do not show anthropogenic
influence and their content can be attributed to the parental rock. The results are compared with previous surveys carried
out in 2003 in order to evaluate temporal deposition trends. No changes were found on reported concentrations except for Cu
and Zn, whose concentration has increased in later years. The results suggest that spatial distribution analysis and results
in comparison with previous studies could be useful for the management and sustainable development of the metropolitan area
of Mexico City. 相似文献