自重可压缩层状球体地球模型下地震变形算法的优化研究

本文利用龙格库塔法求解球坐标系下微分方程组,基于自重、可压缩和连续分层地球模型研究地震引起的地球变形,优化相关算法.首先对传统的两次同向积分法进行调整,对微分方程的齐次部分进行两次相向积分,分别由地心向上积分至震源和由地表向下积分至震源.接着利用震源间断条件求解震源上方和震源下方通解的组合系数,得到微分方程组的解矢量....     

Shear-wave splitting in the crust: Regional compressive stress from polarizations of fast shear-waves

When propagating through anisotropic rocks in the crust, shear-waves split into faster and slower components with almost orthogonal polarizations. For nearly vertical propagation the polarization of fast shearwave (PFS) is parallel to both the strike of the cracks and the direction of maximum horizontal stress, therefore it is possible to use PFS to study stress in the crust. This study discusses several examples in which PFS is applied to deduce the compressive stress in North China, Longmenshan fault zone of east edge of Tibetan plateau and Yunnan zone of southeast edge of Tibetan plateau, also discusses temporal variations of PFS orientations of 1999 Xiuyan earthquake sequences of northeastern China. The results are consistent to those of other independent traditional stress measurements. There is a bridge between crustal PFS and the crustal principal compressive stress although there are many unclear disturbance sources. This study suggests the PFS results could be used to deduce regional and in situ principal compressive stress in the crust only if there are enough seismic stations and enough data. At least, PFS is a useful choice in the zone where there are a large number of dense seismic stations.     

近50 a博斯腾湖逐年水量收支估算与水平衡分析

据博斯腾湖流域1958-2010年期间主要河流开都河、黄水沟、清水河、孔雀河的逐年流量资料,结合焉耆盆地降水、蒸发要素的同期观测资料,对大湖区的逐年水量收支进行计算,并依据水量平衡原理对博湖大湖区残差水量进行了逐年分析。结果表明：（1）1958-2010年期间年均入湖水量14.34×10⁸ m³/a,其中入湖河水约占95%;年均输出水量13.96×10⁸ m³/a,其中大湖区输入孔雀河水量约占43%,湖面蒸发耗水量占57%;湖区年均蓄水量71.57±3.92×10⁸ m³10⁸ m³/a,湖水年均水位为1 047.01±0.94 m;（2）极端水文年度水量平衡分析指出：1986年为最枯年份,入湖河水是多年平均值的62%,而出湖河水量是多年平均值的153%,导致年内湖区水位下降0.94 m;2002年最丰年份入湖河水是多年平均值的2.6倍,致使年内水位上升0.80 m;（3）残差水量逐年“正负”变化指出,湖水与地下水之间存在互补关系,过去53 a间湖水补给地下水的年均水量为0.87×10⁸ m³/a。     

Tracing carbon transfer and assimilation by invertebrates and fish across a tropical mangrove ecosystem using stable isotopes

Mangroves are highly productive ecosystems that exhibit a diverse range of habitats, including tidal creeks and flats, forest gaps and interior forest with varying understory light intensity, tidal dynamics, geomorphological settings, and overall biological production. Within mangrove ecosystems, invertebrates and fish feed on heterogeneous food sources, the occurrence of which is unevenly distributed across the system. This provides a basis for testing models of carbon transfer across mangrove ecosystems. We hypothesized that the carbon transfer and assimilation by fish and invertebrates will vary across the different mangrove habitats and that such variations can be predicted by their stable isotope compositions. We analysed δ¹³C and δ¹⁵N signatures of consumers and their potential organic carbon sources across a tropical mangrove ecosystem in Vietnam. The δ¹³C values of crabs and snails significantly decreased from the tidal flat to interior forest, indicating that variations in carbon transfer and assimilation occurred at small scales <30 m. Reduced variation in δ¹³C of suspension‐feeding bivalves suggested that tidal water was a vector for large‐scale transport of carbon across the mangrove ecosystem. An analysis of co‐variance using habitat as a fixed factor and feeding habit and movement capacity of consumers as co‐variates indicated that habitat and feeding types were major features that affected the δ¹³C values of invertebrates and fish. The findings demonstrate that carbon transfer and assimilation across mangrove ecosystems occur as a diverse combination of small (<30 m) and large (>30 m) scale processes.     

Quantitative characteristics of microorganisms in permafrost at different depths and their relation to soil physicochemical properties

Microorganisms in permafrost can live in cold environments due to coadapted physicochemical processes in this environment. In this paper, the relation between microbial number and soil physicochemical properties at the headwaters area of the Urumqi River is analyzed by using fluorescence microscopy counting and oligo-culture techniques. In total, 20 samples from a 200-cm permafrost core were used as study materials. The study reveals that the number of culturable bacteria has a significantly positive correlation with soil water content, total carbon and total nitrogen concentrations, and a significantly negative correlation with soil pH value. In addition, the ratio of culturable bacteria to total cell number decreases with depths. The results demonstrate that the number of culturable bacteria in permafrost is closely correlated with soil physicochemical properties and depositional age.     

Livelihood differentiation between two villages in Yesanpo Tourism District in China

The rapidly developing rural tourism industry in China has deeply influenced the livelihoods of rural households. This study compares the impact of rural tourism development in poor areas on the farmers’ livelihoods, based on the Sustainable Livelihoods Framework proposed by the United Kingdom’s Department for International Development. Gougezhuang, a tourist village, and Jiaojiekou, a non-tourist village, both located in Yesanpo Tourism District in the state-level povertystricken Laishui County, Hebei Province, were selected as case studies. The livelihood models of the two villages show great differentiation after 20 years of tourism development. Gougezhuang Village has been driven by the tourism industry and farmers are employed locally, enjoying a relatively higher-income life, with a developmental livelihood model. In contrast, farmers in Jiaojiekou Village earn their living mainly by leaving home to work in the city. They have a low income, with a survival livelihood model, supported by part-time business. Considering that the two villages are adjacent and have similar development backgrounds, the analysis results indicate that rural tourism has an apparent locationspecific effect on poverty alleviation and socioeconomic development, but the development of rural tourism is limited regarding large-scale poverty alleviation efforts in poor areas. To implement a propoor- tourism strategy and achieve sustainable development, it is necessary to implement comprehensive management measures to change the local conditions of rural settlements and make full use of the spillover effect of tourist consumption.     

中国8级大震研究及防震减灾学术讨论会将于2001年6月25～27日在兰州召开

由中国地震学会和甘肃省地震局联合举办的“中国 8级大震研究及防震减灾学术讨论会”将于 2 0 0 1年 6月 2 5～ 2 7日在兰州市召开。会议活动安排有 1大会报告 ;2专题报告 ;3学术论文报告分组讨论会 ;4会后考察。会后考察为2个路线。 1线 :兰州—海原—古浪—敦煌 (6月2 8日～ 7月 3日 ) ;2线 :兰州—天水 (6月 2 8日～ 7月 1日 )。欲参会者请与中国地震学会有关专业委员会联系中国8级大震研究及防震减灾学术讨论会将于2001年6月25～27日在兰州召开@董泰     

新太古-古元古代华北陆块构造演化的研究进展

在过去的二十年里 ,华北克拉通早期陆块形成和演化的研究进展是中国固体地球科学研究领域最为显著的成果之一。第一个十年代表性的工作包括深变质变形的层状岩系与块状岩系的识别与成因研究、高级区与绿岩带的划分、构造样式与变形序列研究、变质历史与变质动力学、年代学与地质事件的研究等。第二个十年的研究重点是如何认识和理解早期大陆地壳的性质和它们的形成与演化过程。代表性的进展包括均匀域与地质体的划分、古老微陆块的识别、残留洋壳与早期陆壳的形成、下地壳组成和性质、大陆拼贴机制、古地幔柱构造与前Rodinia超大陆旋回等。其中高压麻粒岩地体和退变质榴辉岩的发现 ,是华北早前寒武纪研究中最重要的进展 ,它为早期大陆的拼合机制、地壳的深部结构和古老下地壳与现代的对比等多个领域打开了新的研究思路。对新太古 -早元古代的重大地质事件的厘定已表明 ,华北主要的地壳生长期是在 2 9～ 2 7亿年 ,但 2 5和 18亿两期事件是重大的事件 ,虽然对其性质尚存争议 ,但越来越多的证据把它们与超大陆和地幔柱构造相联系。     

The Use of a Standpipe to Evaluate Ground Water Samplers

A standpipe system was developed for testing the reliability of ground water samplers. The unit consists of a stainless steel pipe 5 inches (13 centimeters) in diameter and 100 feet (30.5 meters) in height. It has 14 sampling ports from which control samples can be withdrawn at the same time and position as the samples are collected by a sampler lowered to that position. Test solutions were made in two mixing tanks, totaling 260 gallons (980 liters), by diluting the concentrate of five volatile chlorohydrocarbons in water at two levels of concentration: 10-to-30 and 100-to-200 parts per billion (micrograms per liter).
A gas chromatograph interfaced with a purge-and-trap system was used to perform the analyses. Comparisons of the control samples with the sampler-collected samples have indicated that the three non-pumping samplers had recoveries in the range of 92.4 to 103.5 percent and the three pumping samplers had recoveries ranging from 97.7 to 101.5 percent.