共查询到20条相似文献，搜索用时 31 毫秒
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从水文地质条件、充水情况等方面研究影响司家营铁矿Ⅲ采场地下水涌水量因素;在矿区水文地质条件的基础上,进行了矿区地下水均衡计算,通过矿区地下水影响因素的综合分析,计算出矿区地下水总补给量和总排泄量,得出两者的平衡关系;分别采用大井法及数值模拟法,对司家营铁矿Ⅲ采场露天转井下深部开采不同中段的地下水涌水量进行计算,并结合自然降水和考虑露天采场回填废石影响,系统预测了不同开采中段矿坑总涌水量。研究成果表明,矿区地下水呈负均衡状态,对矿区开采呈有利态势;矿坑系统涌水量综合预测结果与阶段性的实测资料较为一致,为司家营铁矿Ⅲ采场井下防排水及地质环境保护奠定了基础。 相似文献
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It is increasingly argued that we are entering into a “biotech century”, in which biotechnology promises major advances in agricultural productivity. The development of biotechnology is not a straightforward affair, however, and the advent of GMOs has led to public protest and consumer resistance. This paper draws upon a comparative Australian-UK project concerned with the role of regulation and governance in mediating the debates and managing the associated risks. Regulatory responses and the mediation of conflicts by the Australian and UK governments have been shaped by the institutional and policy environments in these two countries. The implications of these public debates and regulatory responses for the capture of competitive opportunities are considered. The fact that the two countries have broadly similar systems of governance and regulation reveals how alike the circumstances are in many respects. But at the same time there are important differences in both the style and the content of the policy debates. In both the UK and Australia, the respective central governments remain committed to a ‘biotechnology future’. Against this background, there is little doubt that the choices about biotechnology will play a defining role in shaping the future of rural places. 相似文献
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V. M. Kozlovskii V. V. Travin D. I. Korpechkov M. N. Zaitseva E. B. Kurdyukov A. V. Travin L. B. Terent’eva V. M. Savatenkov 《Geotectonics》2016,50(6):579-597
The Belomorian Mobile Belt (BMB) in northern Karelia mostly consists of gently sloping shear zones, whose gneisses and migmatized amphibolites and blastomylonites are typically thinly banded, with their banding consistently dipping north- and northeastward. These gently sloping shear zones were not affected by folding after they were produced and are not cut by Paleoproterozoic metabasite dikes. Intrusive metabasites in the gently sloping shear zones make up relatively small (usually <5 m) equant or elongate bodies and occur as fragments of larger bodies. These fragments are often concentrated in stripes. Metabasites in the gently sloping shear zone are sometimes also found as lenses and tabular bodies of relatively small thickness, which are conformable with the foliation of the host rocks. The gently sloping shear zones cut across older domains of more complicated structure, which suggests that these zones are gently sloping ductile shear zones. Along these zones, the nappes were thrust south- and southwestward, and this process was the last in the origin of major structural features of BMB when the Paleoproterozoic Lapland–Kola orogen was formed. Practically identical age values were obtained for the gently sloping shear zone in the two widely separated Engonozero and Chupa segments of BMB: 1879 ± 21 Ma (40Ar/39Ar amphibole age of amphibolite whose protolith was mafic rock) and 1857 ± 13 Ma (Sm–Nd mineral isochron age of garnet amphibolites after gabbronorite). The P–T metamorphic parameters in these gently sloping shear zones are remarkably different from the metamorphic parameters outside these zones: the pressure is 3–4 kbar lower and the temperature is 60–100°C lower. Thrusting-related decompression triggered the transition from the older high-pressure episode of Paleoproterozoic metamorphism to a younger syn-thrusting higher temperature metamorphic episode. The peak metamorphic parameters corresponding to the boundary between the amphibolite and granulite facies were reached only in the central portions of the shear zones: T= 680–760°C, P = 8.0–11.9 kbar. In areas of the most intense migmatization, temperature estimates in the central portions of the shear are as high as 810–830°C. The marginal portions of the shear zones were formed at lower temperatures of 610–630°C. The temperature heterogeneous and rock heating in the gently sloping shear zones may have resulted from flows of high-temperature metamorphic fluid that were focused to the central portions of the zones. 相似文献
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The thermoelastic parameters of the CAS phase (CaAl4Si2O11) were examined by in situ high-pressure (up to 23.7 GPa) and high-temperature (up to 2,100 K) synchrotron X-ray diffraction, using a Kawai-type multi-anvil press. P–V data at room temperature fitted to a third-order Birch–Murnaghan equation of state (BM EOS) yielded: V 0,300 = 324.2 ± 0.2 Å3 and K 0,300 = 164 ± 6 GPa for K′ 0,300 = 6.2 ± 0.8. With K′ 0,300 fixed to 4.0, we obtained: V 0,300 = 324.0 ± 0.1 Å3 and K 0,300 = 180 ± 1 GPa. Fitting our P–V–T data with a modified high-temperature BM EOS, we obtained: V 0,300 = 324.2 ± 0.1 Å3, K 0,300 = 171 ± 5 GPa, K′ 0,300 = 5.1 ± 0.6 (?K 0,T /?T) P = ?0.023 ± 0.006 GPa K?1, and α0,T = 3.09 ± 0.25 × 10?5 K?1. Using the equation of state parameters of the CAS phase determined in the present study, we calculated a density profile of a hypothetical continental crust that would contain ~10 vol% of CaAl4Si2O11. Because of the higher density compared with the coexisting minerals, the CAS phase is expected to be a plunging agent for continental crust subducted in the transition zone. On the other hand, because of the lower density compared with lower mantle minerals, the CAS phase is expected to remain buoyant in the lowermost part of the transition zone. 相似文献
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Joy K. Adams 《GeoJournal》2010,75(3):303-314
Sustained migration of Hispanics and Anglos into Texas’s historical “German belt” has contributed to a significant decline
in the proportion of Central Texans claiming German ancestry. Under these circumstances, ethnic festivals are playing an increasingly
important role in maintaining the German-American identity of many of the region’s people and places. Organizers and participants
frequently tout the events’ inclusiveness, claiming that anyone can temporarily cross ethnic boundaries to become “German
for a day” within the festival context. However, participant observation and surveys of festival participants in three historically
German-American communities (Brenham, Fredericksburg, and New Braunfels) suggest that ethnic-themed events mirror processes
of racialization that have persisted in the region for more than 150 years. In this paper, I argue that, in helping to construct
“German” identities for the region’s people and places, German-themed events in Central Texas are implicitly involved in the
construction of “non-German” and, by extension “non-white,” ethnic identities. Further, event participation patterns reflect
a long-standing black-white racial dichotomy in the region. Within this ethnoracial hierarchy, Hispanics have long occupied
a liminal status that is reflected by their involvement in the production and consumption of German-themed events. I contend
that Hispanics’ participation in German heritage festivals reflects not only a historical process of “whitening” their racial
status but their increasing presence and power within the region. 相似文献
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Ling-Ling Xiao Chun-Ming Wu Guo-Chun Zhao Jing-Hui Guo Liu-Dong Ren 《International Journal of Earth Sciences》2011,100(4):717-739
Garnet-bearing metapelites and amphibolites are exposed in the south and middle parts of the Zanhuang complex, which is located
in the central segment of the nearly NS-striking Trans-North China Orogen. These rocks preserve three metamorphic mineral
assemblages forming at the prograde, peak and post-peak decompression stages. The prograde metamorphic stage (M1) is represented by mineral inclusions within garnet porphyroblasts, the peak metamorphic stage (M2) is represented by garnet rims and matrix minerals, whereas the retrograde stage (M3) is represented by amphibole + plagioclase symplectite rimming garnet porphyroblasts in the amphibolites and biotite + plagioclase
symplectite rimming garnet porphyroblasts in the metapelites. All garnet porphyroblasts in the metapelites preserve prograde
chemical zoning except for the ubiquitous, quite narrow zones from the underwent post-peak decompression. It has been determined
through thermobarometric computation that the metamorphic conditions are 650–710°C at 8.2−9.2 kbar for the M1 (inclusion) assemblages, >810°C at >12.5 kbar for the metamorphic peak M2 (matrix) assemblages, and 660–680°C at 4.4–4.5 kbar for the retrograde M3 (symplectite) assemblages. These rocks are thus determined to have undergone metamorphism with clockwise P–T paths involving nearly isothermal decompression (ITD) segments, which is inferred to be related to the amalgamation of the
Eastern and Western Blocks to form the coherent basement of the North China Craton along the Trans-North China Orogen in the
late Paleoproterozoic (1.88–1.85 Ga). 相似文献
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Bearing capacity of foundations is often determined for saturated state of the soil, regarding its simple and conservative
results. This assumption, however, results in very uneconomic and overconservative design for a wide range of climates in
the world. In this paper, plasticity equations were employed and extended for unsaturated soils to establish a theoretical
approach to investigate the bearing capacity of unsaturated soils. It is achieved by combining the concept of effective stress
and plasticity equations in terms of effective stress in unsaturated soils. The advantage of Bishop’s (4) effective stress concept was employed to simplify the equations. The equations were then transformed onto the zero extension
lines directions to generalize this method for both associative and non-associative problems by which both stress and velocity
field can be determined for unsaturated soils. A computer code was also developed to solve the relatively complex plasticity
equations for a wide range of soil friction angles and matric suctions to compute the corresponding bearing capacity factor,
N
γ
, for strip foundations with smooth and rough base. This factor seems to be one of the major contributors in the bearing capacity
of shallow foundations. The results have been presented in design charts and theoretical equations. 相似文献
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X. J. Gao X. J. Fan X. P. Chen Z. Q. Ge 《International Journal of Environmental Science and Technology》2018,15(10):2203-2212
The emergence of antibiotics residues in pharmaceutical industrial wastewater has been a significant environment problem. However, current methods of treating antibiotic-polluted wastewater are inefficient, of high cost and time-consuming. In this study, highly effective enzymatic Fe3O4 magnetic nanoparticles were developed, which is extremely simple and can degrade antibiotics in a fast manner at a low cost. β-Lactamase, a representative enzyme for β-lactam antibiotic degradation, was covalently immobilized on the surface of magnetic nanoparticles modified with amino groups by a simple cross-linking process. The immobilized β-lactamase displayed a wider pH and temperature range for penicillin G degradation than the free enzyme. Meanwhile, the thermostability and storage stability of the immobilized β-lactamase were improved. Fifty milligrams magnetic nanoparticles immobilized with β-lactamase can thoroughly degrade 100 mL penicillin G (5–50 mg L?1) within 5 min. Even if the β-lactamase immobilized on the nanoparticles was reused 35 times in the 5 mg L?1 penicillin G solution, it still kept more than 95% degradation efficiency. These suggest that magnetic nanoparticles immobilized with β-lactamase have a sufficient capacity for degrading antibiotics in wastewater and will serve as a practical and economical solution to antibiotic pollution in pharmaceutical industrial wastewater treatment. 相似文献
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Recently, strong top-down (consumer) control of cordgrass (Spartina alterniflora) has been demonstrated. Here, we manipulated the densities of cordgrass consumers, acridid grasshoppers (Melanoplus bivittatus and Melanoplus femurrubrum), to examine their impact on cordgrass in the Plum Island Estuary (PIE), MA, USA. After 1 month, there was no detectable
effect of grasshopper density on S. alterniflora biomass and grasshoppers at the highest densities (34 individuals per square meter) consumed only ~14% of the standing stock
biomass. However, significant impacts of grasshopper density on grazing damage were seen. For example, plant damage and scarring
length increased by 160% and 6,156%, respectively, at the highest grasshopper densities relative to exclusion (zero grasshoppers)
densities. Plant height was significantly reduced with increasing grasshopper densities, although this may be a function of
leaf tip removal instead of reduced plant growth. No other strong consumers of cordgrass (e.g., Littoraria irrorata, Prokelisia marginata) were observed in PIE and we suggest that consumer regulation of cordgrass is weak in this system. 相似文献
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A. D. Nozhkin I. I. Likhanov K. A. Savko V. V. Reverdatto A. A. Krylov 《Doklady Earth Sciences》2018,479(1):347-351
The results of thermobarometry yielded the P–T parameters of formation and evolution of sapphirine- bearing granulites in the Anabar shield with peak values of UHT metamorphism in the range of T = 920–1000°C at P = 9–11 kbar. Isotope–geochronological data indicate a polymetamorphic evolution of these rocks. Detrital zircon cores in the center of crystals yielded ages of 3.36, 2.75, 2.6, and 2.5 Ga. Later, superimposed metamorphic transformations of the detrital zircon formed rims dated to 2.4, 2.3, 2.2, and 1.83 Ga. A potential provenance source of the detrital zircons could be hypersthene plagiogneisses and metabasics of the Daldyn Group with a premetamorphic age no less than 3.32 Ga and products of their metamorphism of about 2.7 Ga old. 相似文献
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Ronaldo Sousa Pedro Morais Carlos Antunes Lúcia Guilhermino 《Estuaries and Coasts》2008,31(6):1198-1207
The bivalve Pisidium amnicum (Müller 1774) is a common species in several European freshwater ecosystems. However, few Iberian watersheds are colonized
by this species, and the River Minho estuary is possibly the Iberian aquatic ecosystem with the larger population. In October
2004–2007, investigations on spatial and temporal variations in P. amnicum abundance and biomass were carried out at 16 sites along the River Minho tidal freshwater wetlands. Mean abundance and biomass
per site ranged from 0 to 750 ind m−2 and 0 to 7.42 g AFDW m−2, respectively. A clear decrease in the spatial distribution, abundance, and biomass was observed during the 4-year assessment.
Furthermore, a stepwise multiple regression model showed that organic matter and conductivity explained 50.2% of the variation
in P. amnicum abundance (R
2 = 0.502, F
[2, 15] = 7.569, p = 0.005). Ecological knowledge is essential to the implementation of future conservation plans for P. amnicum, and the results of this study are of paramount importance to identify habitats that should be protected in order to preserve
this species and provide scientific reference that may be useful in the development of management and/or restoration plans. 相似文献
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We have mapped the mineralogy onto the H2O-undersaturated liquidus surface of basaltic andesite from North Sister Volcano to constrain the crystalline assemblage with
which, and P–T–H2O conditions at which, the melt last equilibrated before erupting. Combining our high pressure experimental results with examples
of tectonically exposed lower arc crust, geophysical constraints, trace element geochemistry, and melt inclusion volatile
contents, we conclude that an anhydrous, augite-rich gabbro at ∼12 kbar and ∼1,175°C is the most probable lithology with which
North Sister basaltic andesite with ∼3.5 wt% H2O last equilibrated before erupting. We speculate that reaction between this gabbro and primitive mantle-derived precursor
melts buffered the compositions of magmas erupted from this volcano resulting in their remarkably limited compositional range. 相似文献
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Photometry of the nucleus of the Seyfert 1 galaxy Ark 120 acquired in 1996–2005 with telescopes of the Crimean Astrophysical Observatory and the Sternberg Astronomical Institute’s Crimean Laboratory is used to construct and analyze the object’s U BV RI variability. The U BV RI variations have different timescales, and the variability amplitude grows towards shorter wavelengths. Changes in the color indices of the variable source appear to be due to variations in the opacity of gas at temperatures T > 15 000 K. The spectral energy distribution (SED) of the rapidly varying component is bluer than the SED of the slowly-varying component. The rapid variations are due to instabilities in the inner part of the accretion disk where, according to current ideas, the continuum is formed. Based on the peak of the cross-correlation function, the V RI variations lag the B variations by 1.4 to 5.6 days, with the lag increasing systematically from V to I. The lag calculated from the centroid of the cross-correlation function is from 2.8 days for V to 10.5 days for I. We demonstrate that the wavelength dependence of the lag is well approximated by the function τ ∝ λ4/3, characteristic of optically thick accretion disks. 相似文献
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We report strong magnetic linear dichroism (MLD) at the Fe L23 and O K edges of the antiferromagnetic compound hematite -Fe2 O3 in high-resolution orientation- and temperature-dependent electron energy-loss spectroscopy (EELS). Large intensity differences of corresponding spectral features are observed when the Fe L23 and O K edges are measured with momentum transfer either parallel or perpendicular to the magnetization. The resultant difference spectra for the Fe L23 edges is consistent with the MLD observed in X-ray absorption spectroscopy. For the first time we have observed MLD at the O K edge, where the magnetic origin of this dichroism is demonstrated by temperature-dependent investigations across the Morin transition temperature TM= 263 K, at which the Fe electron spins, i.e. the magnetic moments, rotate by 90°. The O K edge MLD is interpreted in terms of superexchange between the spins of the Fe 3d and O 2p electrons through overlapping Fe 3d and O 2p orbitals. The experiments were performed in a transmission electron microscope (TEM), yielding information about the anisotropic electronic structure at nanoscale spatial resolution when operated with a focused electron probe. The effects of MLD at the Fe L23 edges on the determination of Fe3+/Fe in hematite at submicrometre scale using different independent quantification methods are discussed. 相似文献
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