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141.
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143.
北京市春夏季大气气溶胶的单颗粒分析表征 总被引:9,自引:0,他引:9
采集了北京市2000年春夏季大气气溶胶样品5个,采用扫描电镜X射线能谱技术分析大气气溶胶单颗粒约2500个。研究结果表明,沙尘期间,矿物尘是最主要的颗粒物种类,非沙尘期间,北京市大气气溶胶中主要检出矿物尘和含硫颗粒物。夏季随着颗粒物污染的加重,含硫颗粒物的数目百分数增加。是北京市大气颗粒物污染的重要特征。重点讨论了Ca-S颗粒、K-S颗粒和Ca-K-S颗粒三类典型含硫颗粒物的化学组成和粒径分布特征。数目可观的Ca-K-S颗粒以及其他硫酸盐颗粒的生成与相对湿度和云量等气象条件相关,这些颗粒物可能是云中过程的产物。减少SO2排放,减少含硫颗粒物,对于控制北京市的大气颗粒物浓度水平具有重要意义。 相似文献
144.
内蒙古东部闹牛山铜矿成矿地质背景分析 总被引:4,自引:0,他引:4
通过对闹牛山铜矿区与成矿有关的次火山岩岩石化学分析,以及对矿区火山一次火山岩微量元素、稀土元素的分析,结合相关的铅同位素分析,综合分析了该矿床的成矿地质背景。认为:闹牛山铜矿床构造环境属于大陆边缘裂陷带的局部隆起区,成矿火山岩浆为钙碱性,其来源于地壳深部或上地慢,并有上部地壳物质混染。 相似文献
145.
金沙江流域(云南境内)山地灾害危险性评价 总被引:14,自引:1,他引:14
云南境内的金沙江流域是斜坡不稳定的敏感区,根据1988-2000年的区域调查和统计,区内发育山地灾害点1697处,其中流域面积大于1km2的泥石流沟808条,体积大于1×104m3的滑坡580处,体积大于1000m3的崩塌309处。用于山地灾害危险性评价的主要敏感因子包括岩土体类型、山坡坡度、降雨、土地利用、地震烈度和人类活动。在对这些因子进行了敏感性评价的基础上,应用GIS对敏感因子集成评价而产生了云南金沙江流域山地灾害危险性评价图。评价结果表明:高危险区面积占全区面积6464km2的8 77%,中危险区占全区总面积的41 51%,低危险区占41 12%,无危险区占8 60%。山地灾害危险性评价图可以帮助规划者或工程师在土地发展规划中选择最佳建设场所,以减轻灾害的影响。 相似文献
146.
Based on 1961-2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a "vapor transition belt", vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient -0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5o-32.5oN) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas. 相似文献
147.
研究了定点连续形变长周期频段信息和块体构造活动的关系。研究结果表明,在川滇菱形块体内,定点连续形变观测获得的长周期频段信息中的长期趋势变化除去仪器零漂等局部干扰外,基本上都和块体运动方向或者块体边界主干断裂活动方式相一致,表明在定点连续形变长周期频段信息中,也存在有与地震孕育有关的地壳形变信息。对其在预报上的作用做了初步研究。 相似文献
148.
Refining the pre-industrial atmospheric Pb isotope evolution curve in Europe using an 8000 year old peat core from NW Spain 总被引:1,自引:0,他引:1
M.E. Kylander D.J. Weiss A. Martínez Cortízas R. Garcia-Sanchez 《Earth and Planetary Science Letters》2005,240(2):467-485
Pb pollution has existed for several millennia and remains relevant today. By using peat cores as environmental archives it is possible to reconstruct this long history on a regional scale. This is a significant contribution to the findings from ice core records, the only other archive recording purely atmospheric additions. Without information that allows linking and comparison between sites regionally, within Europe and elsewhere, our ability to make coherent global models of the natural Pb cycle, and anthropogenic forcing of this cycle, is limited. In this respect, the characteristics of the Pb pre-pollution aerosol (PPA) are important to define globally. We characterize for the first time a PPA in Southern Europe with [Pb] = 0.78 ± 0.86 μg g− 1, net Pb accumulation rates of 0.032 ± 0.030 mg m− 2 y− 1 and a 206Pb / 207Pb signature of 1.25470 ± 0.02575. This PPA Pb isotope signature is more radiogenic than that found thus far in Western and Northern Europe. Spain is a historically important mining site. Using three-isotope plots and a pool of potential Pb isotope signatures, a detailed source appointment of both natural and anthropogenic Pb sources was made. We found evidence of Saharan aridification and its termination ∼4400 BP and/or agricultural signals and strong local control (from rock and soil) of the Pb PPA. Human impact is first recorded at 3210 BP but does not exceed 50% of deposited Pb until 3005 BP. Mines in SE Spain dominate early Pb pollution history at this site. During the rise of Roman rule, contributions come from mines in N, NW and SW Spain with no strong indication of other European mining activities. In Medieval and Industrial times local contributions to the peat bog are reduced. 相似文献
149.
With the acceleration of industrialization, coal- burning atmospheric pollution is getting more and more serious in many regions in China. However, there are only about ten odd years literature records about pollution in some large and mid-sized cities, where the atmosphere has perhaps been polluted for several decades, and therefore it is difficult to know the process and characteristic of pollution, and diffi-cult to evaluate its damage to environment. Lacustrine sediment, a natural record w… 相似文献
150.
A Possible Detection of the 26 December 2004 Great Sumatra-Andaman Islands Earthquake with Solution Products of the International GNSS Service 总被引:1,自引:0,他引:1
J. Kouba 《Studia Geophysica et Geodaetica》2005,49(4):463-483
The main goal of this work is to critically review the IGS solution products and Precise Point Positioning (PPP) in order
to demonstrate their potential to contribute to studies of large earthquakes such as the one that devastated Southeast Asia
on December 26th, 2004. In view of a possible detection of the Mw 9.0 Sumatra-Andaman Islands Earthquake of December 26, 2004,
position solutions, ranging from intervals of years to one second, of four International GNSS Service (IGS) stations within
3000 km of the epicenter were examined. The IGS combined, cumulative solution product (IGS04P51), consisting of epoch and
station velocity solutions and based on data spans of several years prior to the earthquake, was used as a reference. Four
IGS combined weekly position solutions (igs04P1301-4), two weeks before and after the earthquake, were utilized for the weekly
solution resolution. PPP static and kinematic solutions with IGS Final combined orbits and clocks were used for the mean daily
and instantaneous 5-min and 1-sec epoch solutions, respectively. The most significant changes, detected by both weekly and
daily solutions occurred in longitude. The nearest IGS station ntus, about 1000 km east of the epicenter, moved westward about
15 mm, while the more distant Indian station iisc (∼ 2300 km NW from the epicenter), shifted about 15 mm eastward. In spite
of position errors caused by interpolation of the 5-min IGS clocks, the 1-sec solutions, based on separate data sets, available
only for two stations (iisc, dgar), still showed seismic surface waves, in particular at the Indian station iisc. Precise
daily IGS combined polar motion and length-of-day products, after correcting for the atmospheric effects, also likely detected,
statistically significant, anomalistic excitations on December 26, 2004 that could be caused by this great earthquake. 相似文献