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排序方式: 共有291条查询结果,搜索用时 171 毫秒
261.
韦州矿区地处华北地台西侧与秦祁孤形褶皱带交汇处,含煤地层为石炭-二叠系太原组和山西组,赋存丰富的焦性煤炭资源。通过对矿区煤的挥发分及煤类在垂向、横向上变化规律分析,认为韦州向斜东翼煤层沿倾向呈现深成变质作用,主要以肥煤和焦煤为主,而沿向斜东翼往南、转向西翼,煤层变质程度急剧增高,达到中高变质程度的贫煤和无烟煤.矿区西侧青铜峡-固原断裂西部深处有隐覆岩体存在,使煤层在深成变质作用基础上,叠加了区域岩浆热力变质作用,导致矿区西部煤的变质程度增高。 相似文献
262.
263.
Heating experiments relevant to the depletion of Na,K and Mn in the Earth and other planetary bodies
《Chemie der Erde / Geochemistry》2019,79(4):125540
We have studied the evaporation of Na, K and Mn from Al-Na-K- and Mn-rich silicates at various conditions. Total alkali oxide contents ranged from 5 to 20%. The evaporation rate of Na increases with temperature and decreasing oxygen fugacity and decreases with duration of heating. The loss of K is in all cases less pronounced than for Na. Heating in an evacuated vacuum furnace is more effective in removing Na and K from melt droplets than in furnaces with one atm gas flow of air or gas mixtures controlling the oxygen fugacity. The strong pumping required to keep the vacuum removes Na and K atoms very effectively. In all experiments, the rate of evaporation is determined by quasi-equilibrium between a thin layer of Na and K rich gas above the molten silicates. The results of the experiments are in agreement with several other studies.In experiments with more than one sample in the furnace, equilibration of Na- and K-rich samples with Na- and K-poor samples occurred rapidly, mediated by the ambient gas phase.The results of experiments with Mn in starting compositions showed much stronger losses of Na than Mn under a variety of conditions.Thus the nearly chondritic Mn/Na ratios in the Earth cannot be the result of evaporation of Na and Mn in Earth-making materials, as the Mn/Na ratios in evaporation residues would be much higher than chondritic ratios. Such evaporation processes may have occurred in the parent material of Moon, Vesta and Mars.The data suggest, in agreement with earlier hypotheses, that the high and variable contents of Na and K in chondrules require a gas phase high in Na and K equilibrating with chondrule melts. The volume of nebular gas parental to a certain type of chondrites was heated and Na and K were lost from the chondrule precursors to the gas phase. Subsequently the nebular parcel was compressed leading to higher partial pressures of Na and K. Flash heating then produced chondrule melts which incorporated some of the gaseous Na and K and then cooled rapidly. The large range of Na and K contents in chondrule melts reflects very local enrichments of Na and K in the gas phase. Despite these variations bulk chondritic meteorites have well defined bulk Na and K contents, implying a closed system during formation of chondrules and matrix. 相似文献
264.
应用正相硅胶、生物胶Bio-Beads、凝胶Sephadex LH-20柱色谱和反相HPLC等层析方法,从小粘膜藻(Leathesia nana)中分离得到7个化合物,通过IR、MS、1D和2DNMR等波谱技术鉴定为4-羟基苯甲酸(1)、3.羟乙酰基吲哚(2)、2,3-二溴.4,5-二羟基苯甲醛(3)、3-溴-4,5-二羟基苯甲醛(4)、2,3.二溴-4,5.二羟基苯甲基乙醚(5)、双-(2,3-二溴-4,5-二羟基卞基)-醚(6)和3.溴-4.(2,3-二溴-4,5-二羟基苯甲基)-5-甲氧甲基苯二酚(7)。 相似文献
265.
ZhiGang Zeng ShaoXiong Yu XueBo Yin XiaoYuan Wang GuoLiang Zhang XiaoMei Wang DaiGeng Chen 《中国科学D辑(英文版)》2009,52(7):913-924
The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127°04.5′E, 27°15′N,
water depth 1300–1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate
(samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich
hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd,
Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the 210Pb radioactivity ratios and 210Pb/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf
and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au
and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations
between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the 210Pb/Pb ratios of hydrothermal sulfide samples (3.99×10−5-5.42×10−5), their U isotopic composition (238U content 1.15–2.53 ppm, 238U activity 1.07–1.87 dpm/g, 234U activity 1.15–2.09 dpm/g and 234U/238U ratio 1.07–1.14) and their 232Th and 230Th contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between
200 and 2000 yr.
Supported by the Pilot Project of Knowledge Innovation Project, Chinese Academy of Sciences (Grant No. KZCX2-YW-211), National
Natural Science Foundation of China (Grant Nos. 40830849, 40176020), and Special Foundation for the Eleventh Five Plan of
COMRA (Grant No. DYXM-115-02-1-03) 相似文献
266.
Tomas Nihlén 《Geografiska Annaler: Series A, Physical Geography》2000,82(1):39-44
In 1998 an area near Helagsfjället in Härjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of Helagsfjället. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The five mounds were about 0.6 m high and had an area of about 2 × 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with a hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover. 相似文献
267.
《Geofísica Internacional》2014,53(2):183-198
As a result of a gasoline spill in an urban area, Electrical Resistivity Tomography (ERT), Electromagnetic Profiling (EMP) and Volatile Organic Compounds (VOC) methods were used in order to define the contamination plume and to optimize the drilling and soil sampling activities. The VOC anomalies (recent contamination) indicated that a gas station located at the study site is an active contamination source. The mature contaminated zones defined by ERT and EMP methods corresponded with low resistivity anomalies due to degradation process of the hydrocarbons contaminants. The ERT, EMP and VOC results were integrated on a map, allowing the final configuration of contamination plumes and the optimization of drilling and soil/free-product sampling. Laboratory analyses of free-product samples suggest the existence of more than one contamination event in the site, with the presence of recent and degraded-hydrocarbon contaminants classified in the gasoline range. This study shows the advantages of joint application of ERT, EMP and VOC methods in sites with active contamination source, where the existence of recent and mature contaminants in subsoil is assumed. 相似文献
268.
Blast furnace slag can effectively remediate coastal marine sediments affected by organic enrichment
Satoshi Asaoka 《Marine pollution bulletin》2010,60(4):573-578
There is an urgent need to control nutrient release fluxes from organically-enriched sediments into overlying waters to alleviate the effects of eutrophication. This study aims to characterize blast furnace slag (BFS) and evaluate its remediation performance on organically-enriched sediments in terms of suppressing nutrient fluxes and reducing acid volatile sulfide. BFS was mainly composed of inorganic substances such as CaO, SiO2, Al2O3 and MgO in amorphous crystal phase. Container experiments showed that the phosphate concentration in the overlying water, its releasing flux from sediment and AVS of the sediment decreased by 17-23%, 39% and 16% compared to the control without BFS, respectively. The loss on ignition was significantly decreased by 3.6-11% compared to the control. Thus, the application of BFS to organically-enriched sediment has a suppressive role on organic matter, AVS concentration and phosphate releasing flux from sediments and therefore, is a good candidate as an effective environmental remediation agent. 相似文献
269.
Biological activities of marine benthos such as burrowing and feeding may change sediment characteristics. We conducted three
experiments to examine the potential of using juveniles of a spoon worm Urechis unicinctus to improve the quality of organically contaminated coastal sediment. Sediment samples were collected from a site that was
heavily contaminated with organic matter (Seonso) and two sites that were clean (Myo-do, Dolsan-do). Urechis juveniles, obtained by artificial fertilization and cultured in the laboratory, were introduced to the sediment (weight 3
kg, depth 10 cm) at a density of 500 individuals per aquarium (length 50 cm, width 35 cm, height 30 cm) (Experiment 1), or
at densities ranging from 100 to 900 individuals per beaker (Experiment 2). To examine how sediment contamination can be modified
by the effects of Urechis, 500 individuals (per aquarium) were exposed to the Seonso contaminated sediment that had been mixed with 0–100% clean sand
(Experiment 3). Each experiment lasted two months and sediment samples were collected every 15 d to determine the several
indexes of sediment quality, which included acid volatile sulfide (AVS), chemical oxygen demand (COD) and total ignition loss
(TIL). In Experiment 1, the existence of Urechis did not result in significant changes in quality indexes in the sediments collected from Myo-do, Dolsan-do. However, AVS,
COD and TIL of the Seonso sediment all decreased significantly after co-incubation with Urechis juveniles for 30 to 45 d. Experiment 2 showed that a density of at least 300 juveniles per beaker was necessary to significantly
reduce all three quality indexes, and the magnitude of reduction was positively correlated with juvenile density. Experiment
3 revealed that Urechis juveniles were effective in reducing the AVS, COD and TIL of the Seonso sediment that had been mixed with 60%, 80%, and 80%
of clean sand, respectively. The results of the present study therefore indicated that juveniles of this spoon worm have the
potential to be used to improve the quality of organically contaminated sediment in coastal waters. 相似文献
270.
轴对称多层可压缩渗透各向异性岩基固结分析 总被引:1,自引:0,他引:1
从轴对称固结基本方程出发,通过对时间t、坐标r的Laplace-Hankel变换,再对坐标z的Laplace变换,得到三元一次方程组,解此方程组,并进行Laplace逆变换,得到了单层可压缩渗透各向异性岩基轴对称固结问题的传递矩阵,然后利用传递矩阵法,结合层间连续性条件和边界条件,得到了多层可压缩渗透各向异性岩基轴对称固结问题在积分变换域内的解。最后应用Laplace-Hankel逆变换技术得到轴对称固结问题在物理域内的理论解。编制了相应的计算程序,并进行了数值计算与分析,讨论了可压缩性和渗透各向异性对岩基固结的影响,结果表明:可压缩性越大,岩基瞬时沉降越大;渗透各向异性对固结过程影响明显,但对初始和最终沉降的影响很小。 相似文献