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991.
中国38亿年古陆壳锆石的成因矿物学研究 总被引:1,自引:0,他引:1
本文从锆石晶体形态,环带及晶体从核部于边缘的成分演化等特点,论述了中国最老(38亿年)两个锆石样品的岩浆成因属性,并发现它们的母岩在成因上存在差异,鞍山花岗靡棱岩是地幔或地幔来源为主的花岗质岩石,而冀东铬云母夕线石英岩中锆石的母岩则属壳源或壳幔混合型花风岩石,这些差别表明38亿年华北石陆壳岩石类型具有多样性。 相似文献
992.
利用热力学方法计算了西秦岭铀矿床含矿热液中铀的迁移形式。结果表明,从含矿热液早阶段到主成矿作用发生之前,热液中的铀主要以「UO2(CO3)^0」形式迁移;在晚阶段残余热液中,铀的迁移形式改变为「UO2(SO4)^0」为主。铀迁移形式改变的原因与大气降水中SO^2-4离子的大量带入有关,表明含矿热液来自深部而非大气降水。 相似文献
993.
994.
印度尼西亚砂金资源丰富。LOGAS金矿床是印尼重要砂金矿床之一。它位于苏门答腊金银溅金属成矿带的宽坦河流域的准平原化河谷堆积地带。砂金矿受水系,中低山地形地貌格局和金物质来源的控制,赋存在特定的Qat河流阶地和Qtpu层位砂砾层中,层位稳定,矿床埋深5~12m,砂金品位0.131~0.235g/m3。 相似文献
995.
We consider the ordinary differential equation of the second order, which describes oscillations of a satellite with respect
to its mass center moving along an elliptic orbit with eccentricity e. The equation has two parameters: e and μ. It is regular for 0 ≤ e < 1 and singular when e = 1. For
1 we obtain three limit problems. Their bounded solution to the first limit problem form a two-dimensional (2D) continuous
invariant set with a periodic structure. Solutions to the second limit problem form 2D and 3D manifolds. The μ-depending families
of odd bounded solutions are singled out. One of the families is twisted into a self-similar spiral. To obtain the limit families
of the periodic solutions to the original problem match together the odd bounded solutions to the first and the second limit
problem. The point of conjunction is described by the third (the basic) limit problem. The limit families are very close to
prelimit ones computed in earlier studies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
996.
Stanisław Kasperczuk 《Celestial Mechanics and Dynamical Astronomy》1995,63(3-4):245-253
The reduced Henon-Heiles system is investigated as a Hamiltonian dynamical system obtained by applying the normalization of the HamiltonianH=1/2(p
1
2
+p
2
2
+q
1
2
+q
2
2
)+1/3q
1
3
–q
1
q
2
2
to fourth-degree terms. The related equations of motion are bi-Hamiltonian and possess the Lie-Poisson structure. Each Lie-Poisson structure possesses an associated Casimir function. When reduced to level sets of these functions, the equations of motion take various symplectic forms. The various reductions give different coordinate representations of the solutions. These coordinate representations are used to seek the simplest representation of the solutions. 相似文献
997.
Seasonal and daily variation of mercury evasion at coastal and off shore sites from the Mediterranean Sea 总被引:3,自引:0,他引:3
Maria E. Andersson Katarina Grdfeldt Ingvar Wngberg Francesca Sprovieri Nicola Pirrone Oliver Lindqvist 《Marine Chemistry》2007,104(3-4):214-226
Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hgextr / H', Hgextr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March–April 2004 and October–November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hgextr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600–1150%) was observed during the summer. The spring showed the lowest variation (260–360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500–1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P.S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air–sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(1):373–387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m− 2 h− 1. The summer value was estimated to 22.3 pmol m− 2 h− 1 and the spring to 7.6 pmol m− 2 h− 1. Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons. 相似文献
998.
Takashi Tomiyasu Tomomi Eguchi Masahiko Yamamoto Katsuro Anazawa Hayao Sakamoto Tetsuo Ando Munetomo Nedachi Katsumi Marumo 《Marine Chemistry》2007
To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg− 1 (average 199 μg kg− 1, n = 22) and 23–100 μg kg− 1 (average 55 μg kg− 1, n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter. 相似文献
999.
The Mussel Watch program conducted along the French coasts for the last 20 years indicates that the highest mercury concentrations in the soft tissue of the blue mussel (Mytilus edulis) occur in animals from the eastern part of Seine Bay on the south coast of the English Channel, the “Pays de Caux”. This region is characterized by the presence of intertidal and submarine groundwater discharges, and no particular mercury effluent has been reported in its vicinity. Two groundwater emergence systems in the karstic coastal zone of the Pays de Caux (Etretat and Yport with slow and fast water percolation pathways respectively) were seasonally sampled to study mercury distribution, partitioning and speciation in water. Samples were also collected in the freshwater–seawater mixing zones in order to compare mercury concentrations and speciation between these “subterranean” or “groundwater” estuaries and the adjacent macrotidal Seine estuary, characterized by a high turbidity zone (HTZ). The mercury concentrations in the soft tissue of mussels from the same areas were monitored at the same time.The means of the “dissolved” (< 0.45 μm) mercury concentrations (HgTD) in the groundwater springs were 0.99 ± 0.15 ng l− 1 (n = 18) and 0.44 ± 0.17 ng l− 1 (n = 17) at Etretat and Yport respectively. High HgTD concentrations were associated with strong runoff over short water pathways during storm periods, while low concentrations were associated with long groundwater pathways. Mean particulate mercury concentrations were 0.22 ± 0.05 ng mg− 1 (n = 16) and 0.16 ± 0.10 ng mg− 1 (n = 17) at Etretat and Yport respectively, and decreased with increasing particle concentration probably as a result of dilution by particles from soil erosion. Groundwater mercury speciation was characterized by high reactive-to-total mercury ratios in the dissolved phase (HgRD/HgTD: 44–95%), and very low total monomethylmercury concentrations (MMHg < 8 pg l− 1). The HgTD distributions in the Yport and Etretat mixing zones were similar (overall mean concentration of 0.73 ± 0.21 ng l− 1, n = 43), but higher than those measured in the adjacent industrialized Seine estuary (mean: 0.31 ± 0.11 ng l− 1, n = 67). In the coastal waters along the Pays de Caux dissolved monomethylmercury (MMHgD) concentrations varied from 9.5 to 13.5 pg l− 1 (2 to 8% of the HgTD). Comparable levels were measured in the Seine estuary (range: 12.2– 21.1 pg l−1; 6–12% of the HgTD). These groundwater karstic estuaries seem to be mostly characterized by the higher HgTD and HgRD concentrations than in the adjacent HTZ Seine estuary. While the HTZ of the Seine estuary acts as a dissolved mercury removal system, the low turbid mixing zone of the Pays de Caux receives the dissolved mercury inputs from the groundwater seepage with an apparent Hg transfer from the particulate phase to the “dissolved” phase (< 0.45 μm). In parallel, the soft tissue of mussels collected near the groundwater discharges, at Etretat and Yport, exhibited significantly higher values than those found in the mussel from the mouth of the Seine estuary. We observe that this difference mimics the differences found in the mercury distribution in the water, and argue that the dissolved phase of the groundwater estuaries and coastal particles are significant sources of bioavailable mercury for mussels. 相似文献
1000.
几种海洋生物中硒存在形式初探 总被引:1,自引:0,他引:1
采用不同提取分离方法,分析几种海洋生物中硒的存在形式。结果表明,贻贝、扇贝及海藻中硒有相似的分布特点,大部分硒是以蛋白质和氨基酸形式存在。 相似文献