澧水流域皂市水利枢纽工程地质评价     

黄扬一 《湖南地质》1998,17(2):132-138

本文对皂市水利枢纽的区域稳定性和水库渗漏、浸没、库岸稳定性,矿产淹没以及坝基岩体性状、软弱夹层、坝下冲刷、下游右岸滑坡等工程地质条件与问题进行了全面的分析与评价,结论是库区地形地质条件优良,存在的地质问题易于解决。  相似文献   

Oxygen-total inorganic carbon dioxide relationship in the Pacific Ocean     

Saúl Alvarez-Borrego  P. Kilho Park 《Journal of Oceanography》1973,29(5):193-202

The total inorganic carbon dioxide-oxygen relationship in the ocean has been studied previously using two different approaches, one of which is theoretical and the other is statistical. Discrepancies between the two sets of results have been solved in this work by applying multiple linear regression analysis to express total inorganic carbon dioxide, normalized to constant S‰, as a function of potential temperature and total alkalinity and oxygen normalized to constant S ‰. Results of the regression are in agreement with the assumption that total alkalinity changes in the open ocean are only due to S ‰ changes and calcium carbonate dissolution or precipitation; and with Redfield's model for the prediction of the total inorganic carbon dioxide-oxygen ratio for the biochemical oxidation.  相似文献   

Highly magnetised and differentiated basalts at the 18–19° S propagating spreading centre in the North Fiji Basin     

Horen  Hélène  Fleutelot  Corinne 《Marine Geophysical Researches》1998,20(2):129-137

Geochemical and magnetic properties of basalts dredged along a propagating spreading centre (central part of the North Fiji Basin) have been analysed. Two phenomena appear to be important in controlling variations of natural remanent magnetisation (NRM): 1) an extensive magma differentiation to Fe-Ti basalts increases with the intensity of NRM; and both increase towards the propagator tip, 2) low temperature oxidation (maghemitisation) seems to have already occurred along the ridge axis for the zero age basalts. This paper shows that despite the apparent lack of correlation between NRM and the maghemitisation process (masked by the effect of extensive magma differentiation), the latter involves a change of the domain state of magnetic carriers, from pseudo single-domain to single-domain. We separated the NRM into 4 partial NRMs (pNRM) depending on the coercivity of grains. This analysis showed that the contribution to the remanence of grains with high coercivity increases with maghemitisation, whereas the contribution of grains with weak coercivity decreases.Despite the relatively high degree of maghemitisation, the variations of natural remanent magnetisation intensity principally reflect the variations of magmatic processes. This joint work on magnetic and magmatic properties of basalts collected on the NS-propagating spreading centre from the North Fiji Basin reinforces the magnetic telechemistry hypothesis of Vogt (1979).  相似文献   

Concentrations of mercury in near shore surface waters of the bay of Biscay and in the Gironde Estuary     

D Cossa  J Noël 《Marine Chemistry》1987,20(4)

Total and reactive mercury concentrations have been measured on samples of surface water taken along the shores of the Bay of Biscay and in the Gironde Estuary. In the low turbid areas of the Bay of Biscay the average concentration of total mercury of unfiltered samples is 3.5 ± 0.7 (n = 15) and the reactive mercury 2.1 ± 0.7 (n = 12) pmol l⁻¹; the high levels, up to 27.6 (total mercury) and 4.6 (reactive mercury) pmol l⁻¹ are from the most turbid samples taken from the Marennes-Oléron basin. In the Gironde Estuary, the distribution of total dissolved mercury rises to a peak of concentration (38 pmol l⁻¹) within the high turbidity zone where the salinity is lower than 10‰. The possible origin of this pattern of distribution is discussed.  相似文献   

A three-dimensional dynamic analysis of a towed system   总被引：1，自引：0，他引：1  

Joël V. Sanders 《Ocean Engineering》1982,9(5):483-499

The three-dimensional configuration of a towed cable-body system during prescribed towship maneuvers is determined. Bending resistance and inertia terms are not retained in the towing model; methods are described for ascertaining when these effects are negligible. A physical finite difference formulation is employed to develop the discretized equations of motion, and the system configuration is advanced in time using a Runge-Kutta recurrence algorithm. The response of a reference towed system to a typical maneuver is presented graphically.  相似文献   

Agonistic effect of imidazole and triazole fungicides on in vitro oocyte maturation in rainbow trout (Oncorhynchus mykiss)     

Monod G  Rime H  Bobe J  Jalabert B 《Marine environmental research》2004,58(2-5):143-146

The purpose of the present study was to assess the in vitro effect of some imidazole (prochloraz, imazalil) and triazole (epoxiconazole) agricultural fungicides on gonadotropin-induced oocyte maturation in rainbow trout. Results show that prochloraz, epoxiconazole and imazalil strongly potentiated the induction of oocyte maturation by gonadotropin in a dose-dependent manner. Furthermore, 10(-5) M prochloraz and epoxiconazole alone induced oocyte maturation. The mRNA biosynthesis inhibitor, actinomycin d, completely inhibited oocyte maturation induced by fungicides, suggesting that the gonadotropin-like effect of these chemicals is at least dependent on de novo gene expression.  相似文献   

The Thermodynamic Structure of Arctic Coastal Fog Occurring During the Melt Season over East Greenland     

Gaëlle F. Gilson  Hester Jiskoot  John J. Cassano  Ismail Gultepe  Timothy D. James 《Boundary-Layer Meteorology》2018,168(3):443-467

An automated method to classify Arctic fog into distinct thermodynamic profiles using historic in-situ surface and upper-air observations is presented. This classification is applied to low-resolution Integrated Global Radiosonde Archive (IGRA) soundings and high-resolution Arctic Summer Cloud Ocean Study (ASCOS) soundings in low- and high-Arctic coastal and pack-ice environments. Results allow investigation of fog macrophysical properties and processes in coastal East Greenland during melt seasons 1980–2012. Integrated with fog observations from three synoptic weather stations, 422 IGRA soundings are classified into six fog thermodynamic types based on surface saturation ratio, type of temperature inversion, fog-top height relative to inversion-base height and stability using the virtual potential temperature gradient. Between 65–80% of fog observations occur with a low-level inversion, and statically neutral or unstable surface layers occur frequently. Thermodynamic classification is sensitive to the assigned dew-point depression threshold, but categorization is robust. Despite differences in the vertical resolution of radiosonde observations, IGRA and ASCOS soundings yield the same six fog classes, with fog-class distribution varying with latitude and environmental conditions. High-Arctic fog frequently resides within an elevated inversion layer, whereas low-Arctic fog is more often restricted to the mixed layer. Using supplementary time-lapse images, ASCOS microwave radiometer retrievals and airmass back-trajectories, we hypothesize that the thermodynamic classes represent different stages of advection fog formation, development, and dissipation, including stratus-base lowering and fog lifting. This automated extraction of thermodynamic boundary-layer and inversion structure can be applied to radiosonde observations worldwide to better evaluate fog conditions that affect transportation and lead to improvements in numerical models.  相似文献   

An anilioid snake from the Upper Cretaceous of northern Patagonia     

Raúl O. Gmez  Ana M. Bez  Guillermo W. Rougier 《Cretaceous Research》2008,29(3):481-488

We report the first record of anilioids from southern South America, a region where they do not live today. The fossils come from the Allen Formation (Late Campanian–Early Maastrichtian) at Bajo Trapalcó and Bajo de Santa Rosa localities, Río Negro province, Argentina. The remains consist of several vertebrae, most of which belong to the mid–posterior precloacal region of the column. Comparisons to other extant and extinct anilioid taxa indicate that these remains represent a new taxon, Australophis anilioides gen. et sp. nov. Australophis is morphologically closer to Palaeocene Hoffstetterella from Brazil and extant South American Anilius than to any other snake. These taxa might be closely related, in which case they would represent a lineage distinct from that including Cylindrophis and uropeltids. The two lineages must have diverged by the Late Cretaceous.  相似文献   

Chemical characteristics of pyrites in the Derince sulfide deposit (Elazıǧ Eastern Turkey)     

S. Temur  C. Bölücek  M. Akgül  H. Orhan 《Geochemistry International》2008,46(7):730-741

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Oxygen solubility and speciation in sulphide-rich mattes     

Raúl O.C. Fonseca  Ian H. Campbell  John D. Fitzgerald 《Geochimica et cosmochimica acta》2008,72(11):2619-2635

Sulphide-rich liquids are common in magmatic environments forming over a wide range of temperature, pressure, fO₂ and fS₂. They are economically important because they sequester valuable metals such as Cu, Ni, Au and Pt from silicate melts. The presence of accessory amounts of primary oxides associated with sulphide mineralisations is often ignored or unexplained. Experimental work has shown that large amounts of oxygen can dissolve into mattes at fO₂ typical of terrestrial environments. At the quartz-fayalite-magnetite fO₂ buffer, the molar fraction of O in the matte exceeds that of S, placing the composition of the matte to the magnetite side of the mss (monosulphide solid solution)-magnetite join in the Fe-S-O system. However, sulphides crystallise before magnetite in most sulphide mineralisations and are much more abundant. Moreover, the speciation of O in a matte is not well known. Here we report the results of an experimental study of the solubility of O in mattes as a function of fS₂, fO₂, temperature, and composition. We confirm previous observations that Ni and Cu have a negative effect on the solubility of O in mattes. We show evidence for the existence of FeSO as a structural constituent of mattes in the Fe-S-O system. We present a simple parameterisation of the amount of O dissolved in mattes under relevant geological conditions, and use this parameterisation to discuss mechanisms for the crystallisation of primary spinels associated with sulphides in the Kambalda massive sulphide deposit (Western Australia) and the Sudbury Igneous Complex (Ontario, Canada).  相似文献