陕西小秦岭地区太华群的锆石U-Pb年龄和 Hf同位素组成

本文对陕西华山岩体南侧一个太华群黑云斜长片麻岩进行了地球化学、锆石U-Pb年龄和Hf同位素分析.地球化学分析显示其原岩为中酸性钙碱性花岗质岩石,稀土含量较低( ∑REE =83.13×10-6),但富集Pb和LILE元素(如Rb、Ba).锆石的176Hf/177Hf比值变化于0.281258～0.281404,具明显负的εHf(t)值(-6.86～- 11.23).锆石的Hf同位素模式年龄(2.96 ～3.24Ga)表明原岩是由中太古代地壳演化而来.对比显示小秦岭太华群黑云斜长片麻岩与鲁山地区的太华群具有相似的中太古代地壳源区,但它们的形成时代可能不同.锆石内部结构、Th/U比值以及定年结果显示小秦岭地区的太华群在～1.91Ga经历了一期重要的变质热事件,该事件与Columbia超大陆拼合时的全球性碰撞造山事件相关联.小秦岭太华群为华北克拉通块体南缘的地质单元,但各地区太华群在原岩组成、形成时代和变质时代上具有不同的特征,太华群应是一个杂岩体,至少可以解体为新太古代和古元古代两部分.     

青海共和县加当根斑岩铜矿床成矿流体特征及演化

加当根矿床是近几年新发现的研究程度较低的斑岩型铜矿床,文章对含矿斑岩、石英脉和绢英中的石英岩开展了详细的流体包裹体特征及氢、氧同位素组成研究.该矿床流体包裹体类型丰富,以大量发育含子晶多相包裹体为特征,子矿物种类多样,包括石盐、钾盐、石膏、黄铜矿、黄铁矿、赤铁矿等.石膏、赤铁矿的出现,暗示着岩浆结晶早期处于氧化环境.成矿流体由来自岩浆的高温、高盐度流体和以天水成因为主的中-高温、低盐度流体2个端员组分组成,高温、高盐度流体为主要载矿流体,形成温度＞ 440℃,w(NaCleq)为30％～82％,其是在浅成条件下于岩浆结晶的最后阶段从浅部岩浆中直接出溶形成的;中-高温、低盐度流体主要来源于天水或天水与晚期岩浆热液的混合,温度主要集中在220～360C,w(NaCleq)＜ 20％.石英流体包裹体氢、氧同位素研究表明流体混合在卸载成矿上的重要性,石英脉和绢英岩化阶段是含矿物质沉淀的主要阶段.脉石英的流体温度集中在280～440℃,绢英岩化蚀变石英中流体包裹体的均一温度介于240～340℃.     

“房桥合一”铁路客站抗震计算的快速高效多维虚拟激励法

针对"房桥合一"铁路客站节点数多、空间相互作用显著等特点,利用沿结构整体坐标系方向功率谱的表达式和合理谱强度因子的确定方法,提出能合理考虑地震激励输入角度变化的快速多维虚拟激励法,并以天津西站Ⅱ区作为工程案例,对利用快速多维虚拟激励法、时程响应分析法和已有虚拟激励法的计算结果进行比较。结果表明:三种算法的计算结果吻合较好,证明快速多维虚拟激励法的计算值是合理的;且与已有虚拟激励法相比、快速多维虚拟激励法的计算效率显著提高,更适合于"房桥合一"铁路客站的抗震计算。     

哈尔滨市非职业性一氧化碳中毒潜势预报方法浅探

本文分析了天气形势和气象条件对非职业性一氧化碳中毒的影响,得出了地面高压控制、气温低、相对湿度大、风速小、逆温强、混合层厚度小的天气条件下一氧化碳污染潜势预报等级高的气象特点,从而为非职业性一氧化碳中毒潜势预报提供了较为实用的理论依据。     

梅雨锋云系的结构特征及其成因分析

利用逐时卫星遥感观测资料和地面测站的降水资料，分析了江淮流域2003年6月22～26日暴雨过程中梅雨锋云系的演变、结构特征和形成原因。结果表明，梅雨锋云系为一条TBB的低值带，稳定少动，其上分布着中尺度对流系统（MCS），而中尺度对流系统是由不同尺度、不同强度．的对流单体（包括中β和中γ尺度对流单体）组成的，从而使得梅雨锋云系产生不均匀的降水分布（包括时间上和空间上）。在该暴雨过程中，梅雨锋云系充分体现了中尺度对流系统中所包括的3类组织结构形式。梅雨锋云系与中高纬度云系或热带辐合带云系之间的相互作用与暴雨过程关系密切，梅雨锋云系的维持和发展与强大的黄淮气旋云系直接相关，它是江淮流域上空冷暖气流交汇的结果。     

商丘市近40年日照变化特征及突变分析

对商丘市1961～2000年的年日照和各季节日照资料的分析表明,商丘市年日照时数和各季节日照时数都存在不同程度的减少趋势,年日照时数减少率约为22 h/a,且这种减少的趋势在变缓.使用Mann-Kendall法进行突变检测表明,商丘市年日照时数和各季节日照时数在1982年存在突变现象.     

中国区域高空三种气温、湿度资料交叉对比

本文对比分析了2011—2013年中国区域L波段探空气温、湿度廓线,COSMIC掩星气温、湿度廓线和ERA-Interim再分析资料的气温、湿度廓线之间的差异。对比显示,从时间变化来看,三者之间有很好的正线性相关关系。除10 hPa以上的少数层次外,三种气温资料之间互相吻合较好,彼此偏差范围在±0.4℃之间,偏差标准差在1~2℃,对流层中高层,L波段探空气温受太阳辐射影响较大,气温偏高,与COSMIC相比,L波段探空偏高最高可达到0.64℃。而对于相对湿度,三种数据存在明显差异。对流层中低层到对流层顶L波段探空存在不同程度的偏干,且有较明显的昼夜、季节和区域差异:白天、春夏季和南方潮湿气候区域偏干更明显。一般来说,在对流层顶附近区域,L波段探空相对湿度偏干较明显,200 hPa附近及以上L波段探空相对湿度转为偏湿。在对流层顶以下,L波段探空与COSMIC掩星、ERA-Interim再分析相对湿度具有明显的正相关,对流层顶以上表现为负相关。     

Vertical structures of PM10 and PM 2.5 and their dynamical character in low atmosphere in Beijing urban areas

The vertical structures and their dynamical character of PM2.5 and PM10 over Beijing urban areas are revealed using the 1 min mean continuous mass concentration data of PM2.5 and PM10 at 8, 100, and 320 m heights of the meteorological observation tower of 325 m at Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP CAS tower hereafter) on 10―26 August, 2003, as well as the daily mean mass concentration data of PM2.5 and PM10 and the continuous data of CO and NO2 at 8, 100 (low layer), 200 (middle layer), and 320 m (high layer) heights, in combination with the same period meteorological field observation data of the meteorological tower. The vertical distributions of aerosols observed on IAP CAS tower in Beijing can be roughly divided into two patterns: gradually and rapidly decreasing patterns, I.e. The vertical distribution of aerosols in calm weather or on pollution day belongs to the gradually decreasing pattern, while one on clean day or weak cold air day belongs to the rapidly decreasing pattern. The vertical distributive characters of aerosols were closely related with the dynamical/thermal structure and turbulence character of the atmosphere boundary layer. On the clean day, the low layer PM2.5 and PM10 concentrations were close to those at 8 m height, while the concentrations rapidly decreased at the high layer, and their values were only one half of those at 8 m, especially, the concentration of PM2.5 dropped even more. On the clean day, there existed stronger turbulence below 150 m, aerosols were well mixed, but blocked by the more stronger inversion layer aloft, and meanwhile, at various heights, especially in the high layer, the horizontal wind speed was larger, resulting in the rapid decrease of aerosol concentration, I.e. Resulting in the obvious vertical difference of aerosol concentrations between the low and high layers. On the pollution day, the concentrations of PM2.5 and PM10 at the low, middle, and high layers dropped successively by, on average, about 10% for each layer in comparison with those at 8 m height. On pollution days, in company with the low wind speed, there existed two shallow inversion layers in the boundary layer, but aerosols might be, to some extent, mixed below the inversion layer, therefore, on the pollution day the concentrations of PM2.5 and PM10 dropped with height slowly; and the observational results also show that the concentrations at 320 m height were obviously high under SW and SE winds, but at other heights, the concentrations were not correlated with wind directions. The computational results of footprint analysis suggest that this was due to the fact that the 320 m height was impacted by the pollutants transfer of southerly flow from the southern peripheral heavier polluted areas, such as Baoding, and Shijiazhuang of Hebei Province, Tianjin, and Shandong Province, etc., while the low layer was only affected by Beijing's local pollution source. The computational results of power spectra and periods preliminarily reveal that under the condition of calm weather, the periods of PM10 concentration at various heights of the tower were on the order of minutes, while in cases of larger wind speed, the concentrations of PM2.5 and PM10 at 320 m height not only had the short periods of minute-order, but also the longer periods of hour order. Consistent with the conclusion previously drawn by Ding et al., that air pollutants at different heights and at different sites in Beijing had the character of "in-phase" variation, was also observed for the diurnal variation and mean diurnal variation of PM2.5 and PM10 at various heights of the tower in this experiment, again confirming the "in-phase" temporal/spatial distributive character of air pollutants in the urban canopy of Beijing. The gentle double-peak character of the mean diurnal variation of PM2.5 and PM10 was closely related with the evident/similar diurnal variation of turbulent momentum fluxes, sensible heat fluxes, and turbulent kinetic energy at various heights in the urban canopy. Besides, under the condition of calm weather, the concentration of PM2.5 and PM10 declined with height slowly, it was 90% of 8 m concentration at the low layer, a little lesser than 90% at the middle layer, and 80% at the high layer, respectively. Under the condition of weak cold air weather, the concentration remarkably dropped with height, it was 70% of 8 m concentration at the low layer, and 20%―30% at the middle and high layers, especially the concentration of PM2.5 was even lower.     

地震作用下含软弱夹层顺层岩质边坡表面放大效应研究

为了研究地震作用下含软弱夹层顺层岩质边坡表面的放大效应,借用FLAC3D软件,建立了含软弱夹层顺层岩质边坡动力分析数值模型;在合理考虑地震动输入、边界条件、网格划分与模型参数的基础上,分析了地震动峰值、频率、持时以及初动方向等因素影响下的边坡表面放大效应。研究结果表明：①地震动峰值、频率和初动方向对边坡表面放大效应的影响较显著,而地震动持时对边坡表面放大效应的影响微小;②随着地震动峰值的增加,放大效应由软弱夹层之上的坡面及坡顶面向坡肩点逐渐增大,坡肩点的放大效应最大;③当输入地震动频率小于边坡的自振频率时,边坡表面加速度放大倍数较小,且频率越小,放大倍数越小,当输入地震动频率大于边坡的自振频率时,边坡表面加速度放大倍数较大,且频率越大,放大倍数亦越大。     

人类活动对乌梁素海湿地环境演变的影响分析

乌梁素海是我国半荒漠地区具有很高生态价值和社会效益的大型多功能湖泊湿地[1],是黄河流域最大的淡水湖泊,也是内蒙古河套灌区唯一的承泄途径.乌梁素海的补给水源主要包括含高N,P的农田退水,工业废水以及生活污水,这些退水及废污水的排入使得湿地环境发生着重大的变化.本文在收集1986-2004年19年间Landsat TM/ETM遥感影像数据的基础上,结合乌梁素海历史资料,分析了80年代以来人类活动对湿地环境的影响,这种影响主要体现在人工芦苇面积不断扩大,富营养化程度逐年增高,水生资源迅速减少等方面,尽管2003年以来"引黄入海"工程的实施某种程度上缓解了湿地环境恶化的进程,但湿地环境仍然面临严重的威胁.