Microstructure characteristics and forming environment of late Quaternary Period loess in the Loess Plateau of China

Since the late Quaternary Period, the rapid rising of the northeastern Qinghai-Tibetan Plateau has greatly changed the East Asian climate and formed different regional monsoon climates. Various microstructures of the loess in northern China have formed under a variety of climatic conditions. The scanning electron microscope (SEM) and energy spectrum analysis are used in this paper to study the relationship between the indexes of loess microstructures and the forming climates, and the indexes include the diameter of sand grains, Ca/Fe value and the characteristic shapes of the loess from SEM microstructures pictures. In terms of their respective climatic circumstances, the major microstructures of regional loess may be classified into nine categories according to their forms and particle sizes, such as loess formed in near-sand source, loess of granule sand dropping, and loess formed in hot and rainy places, i.e. with the loess SEM pictures, climates of about 15 ka b.p. in different places may be evaluated. In conclusion, the clear and distinguishable loess microstructures and their indexes in the Loess Plateau of China can also deduce the evolution of climate, such as warm or cold and wet or dry, and even sandstorm activities when the loess is deposited.     

辽河三角洲滨海湿地水域初级生产力研究进展

滨海湿地位于海洋与陆地生态系统的交错过渡带,具有极高的生产力和光合固碳效率,是海岸带蓝色碳汇的重要组成部分。滨海湿地生产力不仅由芦苇、翅碱蓬、红树林等陆上植被提供,水体中浮游植物的光合固碳也是提供初级生产力的重要途径。以往较多的调查和研究集中在陆上植被,而对于滨海湿地水域浮游植物和底栖微藻的报道较少。近年来随着各国政府和学者对二氧化碳排放和气候变化的关注,滨海湿地多圈层生态系统的碳循环和碳汇过程成为研究热点,而湿地水域生产力和光合固碳过程作为多圈层碳循环中重要的一个环节亦应受到足够的重视。以中国北方典型的盐沼湿地区域——辽河三角洲滨海湿地为案例,对湿地水域生产力研究进展进行综述,并对其影响因素进行讨论,以期为国家碳循环与碳中和目标调查提供参考资料。     

浅埋地下结构和土层在动荷载作用下的反应分析

在日本阪神大地震中,地下结构遭到了严重破坏。正确分析地下结构的地震反应,提出合理的抗震设计和安全性评价方法十分必要。用FLAC v4．0对某地的一个地铁车站进行了动力分析,发现随着埋深变浅,土体的加速度时程曲线表现出以某一确定的频率振动,该振动频率与模型的基频相近;位移在正方向和负方向的振幅都随埋深的增加而变小：在地表处达到最大值。一些认识和结论对于正确的进行抗震设计有指导意义。     

800KaB．P．来西藏“一江两河”中游地区的气候与西南季风变化

西藏“一江两河”中游地区风成地层沉积时代、沉积相和磁化率等研究结果表明，早在８００ＫａＢ．Ｐ．前西南季风就已存在，受全球气候波动和青藏高原隆起的影响，其盛行衰变与东南季风具有较好的一致性，主要表现为本区地层所记录的气候变化信息不如东南季风区详细；而且西南季风因高原屏障作用给本区带来的降水愈来愈少，气候明显地向干冷化发展。     

柴达木河都兰区植被覆盖率变化特征

柴达木河都兰区位于青海柴达木盆地东南部,干旱少雨,生态环境脆弱。基于MODIS NDVI数据,应用遥感方法,对都兰区2000—2011年的植被覆盖率进行了计算,并分析了其影响因素。结果表明：研究区内裸土和低覆盖率植被的面积逐年减小,而较低覆盖率、中等覆盖率、较高覆盖率及高覆盖率植被的面积均逐年增加;研究区植被覆盖率与降水及相对湿度呈正相关关系,区域植被生长与地下水埋深的关系较为密切;宗加-诺木洪植被区的地下水埋深范围为0.7～3.5 m,在水埋深为1.7 m的地方,植被长势最好;当研究区的地下水水质矿化度小于3 g·L^-1时,植被发育较好。     

关于澜沧江正源问题

通过对澜沧江源头地区的水文、气候、地貌及河流特征等实地考察后确认,澜沧江正源应为扎阿曲,发源于青海省玉树藏族自治州杂多县阿青乡拉赛贡玛山南面的冰川末端。     

新形势下黑龙江省对俄边境贸易的经济地理透视

本文从世界经贸格局变化和经济地理学角度探讨近两年来黑龙江省对俄罗斯边境地方经济贸易急剧下滑的原因，并立足于资源要素最佳配置的原则对其发展潜力进行了分析，最后提出了我国相应的发展对策。     

δ~(18)O, δD and d-excess signatures of ground ice in permafrost in the Beiluhe Basin on the Qinghai-Tibet Plateau,China

In this paper, stable isotope(δ~(18)O, δD) investigations were completed in ground ice from a deep borehole in the Beiluhe Basin on northern Qinghai-Tibet Plateau to unravel the isotopic variations of ground ice and their possible source water. The δ~(18)O and δD of ground ice show distinctive characteristics compared with precipitation and surface water. The near-surface ground ice is highly enriched in heavier isotopes(δ~(18)O and δD), which were gradually depleted from top to bottom along the profile. It is suggestive of different origin and ice formation process. According to isotopic variations, the ice profile was divided into three sections: the near-surface ground ice at 2.5 m is frozen by the active-layer water which suffered evaporation. It is possible that ground ice between 3 and 4.2 m is recharged by the infiltration of snowmelt. From 5 to 6 m, the ground ice show complex origin and formation processes. Isotopic variations from 6 to 11.1 m and 20.55 m indicate different replenishment water. The calculated slope of freezing line(S=6.4) is larger than the experimental value(5.76), and is suggestive of complex origin and formation process of ground ice.     

古尔班通古特沙漠生境对植物群落格局的影响

This paper reports a geomorphologic landscape investigation, vegetation survey and soil sampling at 14 sites across the Gurbantunggut Desert between 87°37′09"-88°24′04"E and 44°14′04"-45°41′52′Nl. The study encountered 8 species of low trees and shrubs, 5 of perennial herbs, 8of annual plants and 48 of ephemeral and ephemeroid plants. These species of plants represent one-third of the species found in the Gurbantunggut Desert, and their communities make up a large proportion of desert vegetation with great landscape significance. In the investigation we found that the plant communities are accordingly succeeded with the spatial variation of macro-ecoenvironment.Using Principal Component Analysis (PCA) and Correlation Analysis (CA) we found that the micro-ecoenvironment heterogeneity of aeolian sandy soil′s physical and chemical properties such as soil nutrient, soil moisture, soil salt, pH etc. only impacted the diversity of herb synusia (PIEherb) of the desert, with a negative correlation. Meanwhile, the impact of microhabitat on the plant community pattern with an antagonistic interaction made vegetation′s eco-distribution in a temporary equilibrium.     

基于粗糙集和层次分析法的农村居民旅游目的地选择研究

充分考虑主客观因素,运用粗糙集和层次分析法研究农村居民旅游目的地选择影响因子,确定农村居民旅游目的地选择指标体系,并通过评价方法将指标合理化。研究结果表明： ① 判断矩阵计算的各因素权重结果较为接近,比较理想。② 农村居民旅游目的地影响因子中的消费水平、旅游景观、旅游氛围均超过0.1,排在前3位,较以往学者研究结果有所变化。③ 农村居民出游对旅游资源偏好较以往有很大改观。④ 旅游目的地的旅游氛围营造等影响因子已经超过了之前农村居民优先考虑的距离因素。⑤ 对交通条件,住宿水平的影响因子考虑的较少。相对传统的农村居民旅游目的地出游影响因素的研究方法,该方法可以最大限度的避免层次分析法所依赖的专家经验,避免出游因素评价指标设计中出现的重复性。