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11.
The major ion composition of Great Artesian Basin groundwater in the lower Namoi River valley is relatively homogeneous in chemical composition. Traditional graphical techniques have been combined with multivariate statistical methods to determine whether subtle differences in the chemical composition of these waters can be delineated. Hierarchical cluster analysis and principal components analysis were successful in delineating minor variations within the groundwaters of the study area that were not visually identified in the graphical techniques applied. Hydrochemical interpretation allowed geochemical processes to be identified in each statistically defined water type and illustrated how these groundwaters differ from one another. Three main geochemical processes were identified in the groundwaters: ion exchange, precipitation, and mixing between waters from different sources. Both statistical methods delineated an anomalous sample suspected of being influenced by magmatic CO2 input. The use of statistical methods to complement traditional graphical techniques for waters appearing homogeneous is emphasized for all investigations of this type. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Jerzy Mocicki Adam Kotarba Stanisaw Kdzia 《Geografiska Annaler: Series A, Physical Geography》2006,88(2):151-163
This paper discusses direct current resistivity soundings and geomorphological studies of Quaternary deposits in two glacial troughs in the Abisko Mountains of northern Sweden. The subject of the fieldwork is the depth of Pleistocene glacial erosion. Studies were carried out in 1998 and 2003 in the Kärkevagge and Vassivagge. The estimated thickness of Quaternary deposits and bedrock properties are discussed in the broader context of glacial erosion studies in the Abisko area. Geophysical and geomorphological studies suggest that the depth of glacial erosion was highly differentiated from –190 m in the Torneträsk basin to the metric overall erosion on the upland plateau. In medium‐sized valleys several kilometres long, erosion depth measures 30–50 m. Present‐day stream channel patterns reveal a strong relation to the bedrock configuration in valley floors 相似文献
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15.
Pounding of adjacent superstructure segments in elevated bridges during severe earthquakes can result in significant structural damage. The aim of this paper is to analyse several methods of reduction of the negative effects of collisions induced by the seismic wave propagation effect. The analysis is conducted on a detailed three‐dimensional structural component model of an isolated highway bridge. The results show that the influence of pounding on the structural response is significant in the longitudinal direction of the bridge and significantly depends on the gap size between superstructure segments. The smallest response can be obtained for very small gap sizes and for gap sizes large enough to prevent pounding. Further analysis indicates that the bridge behaviour can be effectively improved by placing hard rubber bumpers between segments and by stiff linking the segments one with another. The experimental results show that, for the practical application of such connectors, shock transmission units can be used. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
16.
Lui-Heung Chan John C. Lassiter Erik H. Hauri Stanley R. Hart Jerzy Blusztajn 《Earth and Planetary Science Letters》2009,277(3-4):433-442
Radiogenic isotope variations in lavas from the Cook–Austral volcanic chain have delineated three distinct mantle sources: a HIMU component, a depleted component (DM), and an enriched component (EM). To better constrain the mantle sources for South Pacific hot spot volcanism, we determined lithium isotopic compositions of lavas from Raivavae, Rapa, Mangaia and Tubuai of the volcanic chain. The study includes whole rock and mineral analyses. In general, δ7Li of most olivines resemble bulk rock composition whereas clinopyroxenes are variably lighter. This implies that clinopyroxene is more susceptible to diffusion-induced fractionation, in agreement with previous studies. Olivine δ7Li values span a narrower range than whole rock values, and do not extend to the very heavy compositions previously reported in HIMU bulk lavas. This discrepancy likely reflects alteration of bulk lavas, and suggests that Li-isotope analyses of bulk lavas should be interpreted with caution. Olivines from HIMU lavas have heavy δ7Li values (up to 6.2‰), and extend beyond the range reported for fresh MORB. Correlations between Li-isotopes and radiogenic isotopes suggest that the heavy δ7Li values in HIMU olivines are a source characteristic and not the result of post-magmatic alteration. Although the Li-isotope composition of recycled, dehydrated oceanic crust is currently under debate, our results suggest that HIMU lavas derive from a source containing recycled dehydrated oceanic crust, and that the “heavy” Li-isotope signature of altered oceanic crust is partially preserved during passage through the subduction factory. 相似文献
17.
Mineral constituents in common chanterelles and soils collected from a high mountain and lowland sites in Poland 总被引:1,自引:1,他引:0
This paper reported the results of the determination of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn in Common Chanterelles (Cantharellus cibarius) Fr. and surface soil layer (0-10 cm) underneath the fruiting bodies. Mushrooms and soils were collected from a lowland site in the Hel Peninsula (Baltic Sea coast) and a high mountain site in the Tatra Mountains. The trace elements were determined using validated method and inductively coupled plasma - atomic emission spectroscopy (ICP-AES). Common Chanterelles that emerged at sites poor in mineral nutrients podzols of the Hel Peninsula forests efficiently bioconcentrated several essential trace elements (K, P, Co, Cu, Mn, Na, Zn), while the abundance of those elements in carpophores was around half less compared to specimens from Zakopane region and which emerged in soils much richer in minerals. Common Chanterelles collected at two spatially distant background areas in Poland were only weakly contaminated with metals such as Ag, Cd, Hg and Pb. The maximum tolerable Cd and Pb contents of certain cultivated mushrooms are regulated in the European Union by law and these hazardous metals in C. cibarius were far below tolerance limits set. 相似文献
18.
Jerzy Dec 《Acta Geophysica》2010,58(1):5-14
This paper shows the results of seismic research on some problems of sulphur in-situ mining. The difficulties during exploitation
were mainly connected with the lack of detailed information on the structure and tectonics of deposit and overburden strata.
This kind of information could be obtained using the High Resolution Seismic method.
The use of seismic method allows to determine the range of subsidence provoked by well mining of sulphur. It is very important
to undertake the measurements before exploitation, because the comparison of seismic sections before and during exploitation
creates a possibility of determining the process of changes in the structure of the deposit and overburden strata. 相似文献
19.
Viability of pyrite pulled metabolism in the ‘iron-sulfur world’ theory: Quantum chemical assessment
Andrea Michalkova Dmytro Kosenkov Leonid Gorb Jerzy Leszczynski 《Geochimica et cosmochimica acta》2011,75(7):1933-1941
The viability of pyrite-pulled metabolism in the ‘iron-sulfur world’ theory was assessed using a simple model of iron-nickel sulfide (Fe-Ni-S) surface and data obtained from quantum chemical calculations. We have investigated how the individual reactions in the carbon fixation cycle (carboxylic acids formation) on an Fe-Ni-S surface could have operated to produce carboxylic acids from carbon oxide and water. The proposed model cycle reveals how the individual reactions might have functioned and provides the thermodynamics of each step of the proposed pathway. The feasibility of individual reactions, as well the whole cycle was considered. The reaction of acetic acid production from CH3SH and CO on an Fe-Ni sulfide surface was revealed to be endergonic with a few partial steps having positive Gibbs free energy. On the other hand, the pyrite formation was found to be slightly exergonic. The significance of the catalytic activity of transition metal sulfides in generation of acetic acid was shown. The Gibbs free energy values indicate that the acetic acid synthesis is unfavorable to proceed on the studied Fe-Ni-S model under simulated conditions. The importance of these results in terms of a primordial chemistry on iron-nickel sulfide surfaces is discussed. 相似文献
20.
Comparison of source parameters estimated in the frequency and time domains for seismic events at the Rudna copper mine,Poland 总被引:3,自引:0,他引:3
Source parameters estimated in the frequency domain for 100 selected seismic events from the Rudna copper mine, with moment
magnitude ranging from 1.4 to 3.6, were collected to study their scaling relations and to compare them with the parameters
estimated in the time domain. The apparent stress and static stress drop, corrected for the limited bandwidth recording, increase
slightly in a similar manner with increasing seismic moment. The ratio of apparent stress to static stress drop, a measure
of radiation efficiency, is practically constant and its mean value is close to 0.1.
For 37 seismic events, with moment magnitude between 1.9 and 3.4, source parameters were estimated in the time domain from
relative source time functions, that displayed unilateral rupture propagation, and their rupture velocity could be estimated.
It ranges from 0.23 to 0.80 of shear wave velocity and is almost independent of seismic moment. The fault length, estimated
from the average source pulse width and rupture velocity, is clearly dependent on seismic moment and is smaller than the source
radius estimated from the corner frequency on the average by about 25 percent. There is no correlation between the values
of static stress drop estimated in the frequency and time domains, but the time domain stress drop is in general similar to
that estimated in the frequency domain. The apparent stress increases with increasing rupture velocity, and the ratio of apparent
stress to static stress drop seems also to depend on rupture velocity. 相似文献