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951.
硅酸盐样品微波加热碱熔分解方法 总被引:1,自引:0,他引:1
本文研究了硅酸盐样品在常压下,用微波炉进行碱熔分解的熔样时间,试剂用量和滴加水量等情况对分解的影响,确定了最佳实验条件,将此法用于地球化学标准参考样品SiO2的测定,取得了满意的结果。 相似文献
952.
歧口凹陷侏罗系火成岩主要以中-酸性的流纹岩、粗面岩和粗面安山岩为主,白垩系主要为中-基性的粗面玄武岩和玄武质粗面安山岩,第三系火成岩以粗面玄武岩、碱性玄武岩及辉绿岩为主。同位素定年结果获得白垩系玄武岩的年龄为133±20 Ma,安山岩和粗安岩年龄分别为111.8±0.9 Ma和122.1±3.1 Ma,第三系辉绿岩年龄为16.57±0.23 Ma。地球化学特征显示,侏罗系火成岩相对低钛、高碱和钠、低铁镁,轻重稀土元素强烈分馏、微量元素相对富集LILE、贫化HFSE、亏损Nb和Ti、P,部分高Sr、低Yb,总体指示为挤压环境下加厚地壳物质的熔融产物,白垩系火成岩中等钛和碱的含量,高钠、铁和镁,稀土和微量元素显示其来自于伸展背景的富集地幔源,但受到陆壳物质的混染,第三系火成岩高钛含量、中等碱含量但变化大、高钠、富铁镁,轻重稀土元素分馏弱到中等、微量元素富集LILE和HFSE,同样来自板内伸展环境的富集地幔源的产物。表明歧口凹陷构造转换发生在晚侏罗世和早白垩世之间。 相似文献
953.
A model for retrieval of dual linear polarization radar fields from model simulation outputs 总被引:4,自引:0,他引:4
An algorithm for retrieving polarimetric variables from numerical model fields is developed. By using this technique, radar reflectivity at horizontal polarization~ differential reflectivity, specific differential phase shift and correlation coefficients between the horizontal and vertical polarization signals at zero lag can be derived from rain, snow and hail contents of numerical model outputs. Effects of environmental temperature and the melting process on polarimetric variables are considered in the algorithm. The algorithm is applied to the Advanced Regional Prediction System (ARPS) model simulation results for a hail storm. The spatial distributions of the derived parameters are reasonable when compared with observational knowledge. This work provides a forward model for assimilation of dual linear polarization radar data into a mesoscale model. 相似文献
954.
The similar features of two El Nino(1982/83 and 1986/88)events in the formation and developmentprocess are revealed based on the analysis of the oceanic and atmospheric data in the present paper Forinstance,the timing of the warming onset and ending was late,the warming region first took place in theequatorial central Pacific,and the propagation of warming event is from west to east.Moreover,it is shownthat the two El Nino events both exerted a significant impact to the strength and the westward extension ofthe subtropical high over the Northwest Pacific.The atmospheric response to this SST anomaly was alsovery marked with the persistent PNA pattern observed in Pacific-North American region.Both events hadthe striking impact on the winter weather process and climate in China,but with considerable differences.On the basis of the analysis of all El Nino events in the recent 40 years,it has been found that the rainfallduring Meiyu period in Changjiang River Basin is associated with the season of El Nino onset. 相似文献
955.
956.
The ecological environment in the East China Sea (ECS) and the Yellow Sea (YS) has changed significantly due to sea-level rising and the Kuroshio incursion since the last deglaciation. In this study, biomarker records of core F10B from the mud area southwest off Cheju Island (MSWCI) were generated to evaluate phytoplankton productivity and community structure changes in response to environmental evolution during the last 14 kyr. The contents of diatom, dinoflagellate and haptophyte biomarkers (brassicasterol, dinosterol and C37 alkenones) display similar trends, with increasing phytoplankton productivity during the last 14 kyr due to the increased influences of the Kuroshio, and especially due to the eddy-induced upwelling during the late Holocene. On the other hand, the contents of terrestrial biomarkers (C28 +C30 +C32 n-alkanols) and terrestrial organic matter (TOM) proxies (TMBR’ and BIT) all reveal decreasing TOM input into the area around the sampling site for the 14 kyr, mostly due to sea-level rising. Phytoplankton biomarker ratios reveal a shift from a haptophyte-dominated community at 6.2–2.5 kyr BP to a diatom-dominated community at 2.5–1.45 kyr BP, likely caused by a stronger cold eddy circulation system at 2.5–1.45 kyr BP in the MSWCI. 相似文献
957.
1999年6月28日~7月19日在敦煌场, 7月25日~7月31日在青海湖水面场进行了一次大规模综合野外测量试验, 其中采用3台先进的法国CIMEL太阳辐射计对两个场地大气光学特性进行了系统全面测量, 获得大量晴空天气条件下的大气光学数据。利用Langley法处理气溶胶通道数据得到气溶胶光学厚度及其光谱变化。测量结果显示550 nm波长平均气溶胶光学厚度分别为0.12、0.18, 由气溶胶光学厚度的波长变化得到气溶胶Junge参数分别为2.6、3.0, 并与几种典型气溶胶类型比较。结果表明两地在晴空天气里, 气溶胶含量较小, 符合遥感卫星传感器辐射定标的大气条件。 相似文献
958.
Shallow water flow (SWF), a disastrous geohazard in the continental margin, has threatened deepwater drilling operations. Under overpressure conditions, continual flow delivering unconsolidated sands upward in the shallow layer below the seafloor may cause large and long-lasting uncontrolled flows; these flows may lead to control problems and cause well damage and foundation failure. Eruptions from over-pressured sands may result in seafloor craters, mounds, and cracks. Detailed studies of 2D/3D seismic data from a slope basin of the South China Sea (SCS) indicated the potential presence of SWF. It is commonly characterized by lower elastic impedance, a higher Vp/Vs ratio, and a higher Poisson’s ratio than that for the surrounding sediments. Analysis of geological data indicated the SWF zone originated from a deepwater channel system with gas bearing over-pressured fluid flow and a high sedimentation rate. We proposed a fluid flow model for SWF that clearly identifies its stress and pressure changes. The rupture of previous SWF zones caused the fluid flow that occurred in the Baiyun Sag of the northern SCS. 相似文献
959.
Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on evapotranspiration is helpful in understanding the impact of climate change on hydrological processes. In this paper, based on the daily meteorological data from 1960 to 2007 within and around the Aksu River Basin, reference evapotranspiration (RET) was estimated with the FAO Penman-Monteith method. The temporal and spatial variations of RET were analyzed by using ARCGIS and Mann-Kendall method. Multiple Regression Analysis was employed to attribute the effects of the variations of air temperature, solar radiation, relative humidity, vapour pressure and wind speed on RET. The results showed that average annual RET in the eastern plain area of the Aksu River Basin was about 1100 mm, which was nearly twice as much as that in the western mountainous area. The trend of annual RET had significant spatial variability. Annual RET was reduced significantly in the southeastern oasis area and southwestern plain area and increased slightly in the mountain areas. The amplitude of the change of RET reached the highest in summer, contributing most of the annual change of RET. Except in some high elevation areas where relative humidity predominated the change of the RET, the variations of wind velocity predominated the changes of RET almost throughout the basin. Taking Kuqa and Ulugqat stations as an example, the variations of wind velocity accounted for more than 50% of the changes of RET. 相似文献
960.
ThereisanunanimousunderstandingthattheUHPmetamorphisminDabie-SuluareaswasformedduringtheTri-assiccollisioneventbetweentheYangtzeandNorthChinacratons(Congetal.,l994$Zhouetal-,l996;Liouetal.,l994)-Eclogiteisthemostimportantrocktypeamongtheul-trahigh-pressure(UHP)metamorphicrocks.Accordingtotheiroccurrencethereare3typesofeclogites:typeIisen-clavesinultramaficintrusionsandasmembersinthelayeredmafic-ultramaficcomplex(Jahnl998);typeIispodsorlay-ersinthehighlymetamorphicsupracrustals(mainlying… 相似文献