The carbohydrates in relation to mineralogic and granulometric composition of surface sediments in the karst estuary (River Krka estuary,Yugoslavia)     

Olga Hadz̆ija  Mladen Jurac̆ić  Marija Luić  Maja Tonković  Biserka Jeric̆ević 《Estuarine, Coastal and Shelf Science》1985,21(5):701-709

The investigation of mineral, granulometric and chemical composition of sediments of the River Krka estuary (Yugoslavia) were performed in order to elucidate the origin of the sediments and the pattern of sedimentation. Estuarine surface sediments were found to be fine-grained with a bimodal distribution. Environmental conditions in estuarine sediments favour conservation of the organic matter (anoxic conditions). The carbohydrates in the sediments were investigated to determine whether they are of terrigenous or authigenous origin. Glucose, galactose, mannose, xylose, rhamnose, glucosamine and glucuronic acid were detected in the sediments. Their mutual relationship indicates a preferentially terrigenous source of sedimented organic material in estuarine sediments.  相似文献   

Physical characteristics of Comet Nucleus C/2001 OG₁₀₈ (LONEOS)     

Paul A. Abell  Yanga R. Fernández  Petr Pravec  Tony L. Farnham  Paul S. Hardersen  Peter Kušnirák  Scott S. Sheppard 《Icarus》2005,179(1):174-194

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A comparative study of the zooplankton in two adjacent embayments,Port Phillip and Westernport Bays,Australia     

William J. Kimmerer  A.David McKinnon 《Estuarine, Coastal and Shelf Science》1985,21(2):145-159

We report on a year's study of spatial and seasonal patterns of zooplankton abundance in Port Phillip and Westernport Bays, July 1982 to August 1983. These two bays, closely adjacent on the southern coast of Victoria, Australia, differ in several respects: Port Phillip is a nearly landlocked bay with a broad basin, while Westernport is an open tidal embayment with extensive mud and seagrass banks. Both bays have a resident zooplankton fauna distinct from that of Bass Strait. Although these resident communities have many species in common, patterns of abundance and dominance are quite different. We found that the holoplankton of Port Phillip was about half copepods, mostly Paracalanus indicus, with 23% Caldocera and 21% larvaceans. Westernport Bay zooplankton was dominated by Acartia tranteri, with no resident cladoceran fauna. Bass Strait species were more often found in Westernport than in Port Phillip Bay, but the resident community of Port Phillip Bay was more similar to that of Bass Strait than to that of Westernport.Although this study was undertaken in an exceptionally dry year, the available historical data show that the overall patterns found in 1982–1983 are typical for these bays. The differences in community composition probably relate to differences in depth profile, predator abundance, and suspended matter between the bays.  相似文献   

八庙—青山金红石矿床化学成分与成矿关系     

徐少康  李博昀  程建祖  刘振山 《河南国土资源》1996,(4)

本矿床是我国金红石矿床重要的成因及工业类型，为具有特定化学成分的岩石在特定变质条件下形成的。本文通过对大量数据的处理，查明了化学成分与成矿的关系：高Ａｌ２Ｏ３、ＭｇＯ、Ｆｅ２Ｏ３＋ＦｅＯ、Ｋ２Ｏ、Ｐ２Ｏ５、Ｈ２Ｏ＋、ＭｎＯ，低ＳｉＯ２、ＣａＯ、Ｎａ２Ｏ、ＣＯ２、Ｓ等，利于钛富集；高ＴｉＯ２、ＭｇＯ、Ｐ２Ｏ５、Ｓ，低ＳｉＯ２、ＣａＯ、Ｋ２Ｏ、Ａｌ２Ｏ３、Ｆｅ２Ｏ３／ＦｅＯ，利于金红石形成；高Ｓｃ、Ｚｒ、Ｎｉ、Ｚｎ及Ｌａ／Ｙｂ，低Ｙ、Ｎｂ、Ｔｈ、Ｃｄ、Ｂａ、Ｂｅ、ΣＲＥＥ，利于金红石纯度提高。对研究矿床成因及寻找新的同类矿床等有重要意义  相似文献   

鞍山地区中、上鞍山群变质沉积岩中黑云母化学成分及其意义     

刘道荣 《国土资源》1990,(3)

通过对中、上鞍山群变质沉积岩中黑云母化学成分的对比,确认区内两层位黑云母化学组分存在一定差异,这种差异主要反映了其形成时变质条件的不同。随变质程度增加,区内黑云母的Si、AI~Ⅵ,Fe~(3 )、Mg和K含量增加,而Fe~(2 )、Al~Ⅳ和CH降低,Mg/Fe~(2 )比值从1.00增至2.18。中鞍山群黑云母变质温度为550—620℃,变质压力在5×10~8Pa左右;上鞍山群黑云母变质温度为450-500℃,变质压力低于5×10~8Pa。黑云母含铁系数(f)可作为鞍山地区寻找富铁矿的一种标志。  相似文献   

Challenging a Paradigm: Do We Need Active and Inactive Areas to Account for Near-Nuclear Jet Activity?     

Crifo  J.-F.  Rodionov  A. V.  Szegö  K.  Fulle  M. 《Earth, Moon, and Planets》2002,90(1-4):227-238

We briefly describe an advanced 3D gas dynamical model developed for the simulation of theenvironment of active cometary nuclei. The model canhandle realistic nucleus shapes and alternative physical models for the gas and dust production mechanism.The inner gas coma structure is computed by solving self-consistently(a) near to the surface the Boltzman Equation(b) outside of it, Euler or Navier-Stokes equations.The dust distribution is computed from multifluid ``zero-temperature' Euler equations,extrapolated with the help of a Keplerian fountain model.The evolution of the coma during the nucleus orbital and spin motion,is computed as a succession of quasi-steady solutions. Earlier versions of the model using simple,``paedagogic' nuclei have demonstrated that the surface orographyand the surface inhomogeneity contribute similarly to structuring the near-nucleusgas and dust coma,casting a shadow on the automatic attribution of such structures to ``active areas'.The model was recently applied to comet P/Halley, for whichthe nucleus shape is available. In the companion paper of this volume,we show that most near-nucleus dust structuresobserved during the 1986 Halley flybys are reproduced, assuming that the nucleus is strictly homogeneous. Here, we investigate the effect of shape perturbations and homogeneityperturbations. We show that the near nucleus gas coma structure is robust vis-a-vissuch effects. In particular, a random distribution of active and inactive areaswould not affect considerably this structure, suggesting that such areas,even if present, could not be easily identified on images of the coma.  相似文献   

Latitudinal transport by barotropic waves in Titan's stratosphere.: II. Results from a coupled dynamics-microphysics-photochemistry GCM     

D. Luz  F. Hourdin  S. Lebonnois 《Icarus》2003,166(2):343-358

We present a 2D general circulation model of Titan's atmosphere, coupling axisymmetric dynamics with haze microphysics, a simplified photochemistry and eddy mixing. We develop a parameterization of latitudinal eddy mixing by barotropic waves based on a shallow-water, longitude-latitude model. The parameterization acts locally and in real time both on passive tracers and momentum. The mixing coefficient varies exponentially with a measure of the barotropic instability of the mean zonal flow. The coupled GCM approximately reproduces the Voyager temperature measurements and the latitudinal contrasts in the distributions of HCN and C₂H₂, as well as the main features of the zonal wind retrieved from the 1989 stellar occultation. Wind velocities are consistent with the observed reversal time of the North-South albedo asymmetry of 5 terrestrial years. Model results support the hypothesis of a non-uniform distribution of infrared opacity as the cause of the Voyager temperature asymmetry. Transport by the mean meridional circulation, combined with polar vortex isolation may be at the origin of the latitudinal contrasts of trace species, with eddy mixing remaining restricted to low latitudes most of the Titan year. We interpret the contrasts as a signature of non-axisymmetric motions.  相似文献   

The geochemistry of gem opals as evidence of their origin     

Eloïse Gaillou  Aurlien Delaunay  Benjamin Rondeau  Martine Bouhnik-le-Coz  Emmanuel Fritsch  Guy Cornen  Christophe Monnier 《Ore Geology Reviews》2008,34(1-2):113

Seventy-seven gem opals from ten countries were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) through a dilution process, in order to establish the nature of the impurities. The results are correlated to the mode of formation and physical properties and are instrumental in establishing the geographical origin of a gem opal. The geochemistry of an opal is shown to be dependant mostly on the host rock, at least for examples from Mexico and Brazil, even if modified by weathering processes. In order of decreasing concentration, the main impurities present are Al, Ca, Fe, K, Na, and Mg (more than 500 ppm). Other noticeable elements in lesser amounts are Ba, followed by Zr, Sr, Rb, U, and Pb. For the first time, geochemistry helps to discriminate some varieties of opals. The Ba content, as well as the chondrite-normalized REE pattern, are the keys to separating sedimentary opals (Ba > 110 ppm, Eu and Ce anomalies) from volcanic opals (Ba < 110 ppm, no Eu or Ce anomaly). The Ca content, and to a lesser extent that of Mg, Al, K and Nb, helps to distinguish gem opals from different volcanic environments. The limited range of concentrations for all elements in precious (play-of-color) compared to common opals, indicates that this variety must have very specific, or more restricted, conditions of formation. We tentatively interpreted the presence of impurities in terms of crystallochemistry, even if opal is a poorly crystallized or amorphous material. The main replacement is the substitution of Si⁴⁺ by Al³⁺ and Fe³⁺. The induced charge imbalance is compensated chiefly by Ca²⁺, Mg²⁺, Mn²⁺, Ba²⁺, K⁺, and Na⁺. In terms of origin of color, greater concentrations of iron induce darker colors (from yellow to “chocolate brown”). This element inhibits luminescence for concentrations above 1000 ppm, whereas already a low content in U (≤ 1 ppm) induces a green luminescence.  相似文献   

圆盘固相萃取富集-气相色谱法测定地表水中有机氯和有机磷农药   总被引：4，自引：2，他引：2  

何淼  饶竹 《岩矿测试》2008,27(1):12-16

采用环境友好的圆盘固相萃取新技术富集水体中有机氯农药和有机磷农药,分别用微池电子捕获检测器(μECD)和火焰光度检测器(FPD)气相色谱法检测,实现了水中有机氯和有机磷农药残留物的测定。结果表明,16种有机氯农药的平均回收率为64.7%~102%,精密度(RSD,n=6)为2.9%~15%;13种有机磷农药的平均回收率为65.9%~104%,精密度(RSD,n=6)为1.7%~17%。方法快速、灵敏、低污染,可用于水体中多种有机氯农药和有机磷农药的残留分析。  相似文献   

流体包裹体成分测定的低温相变和显微拉曼光谱分析技术研究进展   总被引：2，自引：1，他引：1  

葛云锦  陈勇  周瑶琪 《岩矿测试》2008,27(3):207-210

论述了包裹体低温分析技术的原理以及进展。传统的流体包裹体低温分析技术是以显微冷冻测温测定无机盐体系为主,目前已发展到应用低温原位拉曼光谱技术对包裹体中的阳离子和阴离子进行定量-半定量分析。油气包裹体原位低温分析技术也取得了较大的突破,对不同成分油气包裹体低温下的相变过程取得了一定的认识,据此对油气包裹体进行分类,推测其主要成分,为油气包裹体计算提供基础参数。  相似文献