基于IGS连续运行站的地壳非对称运动趋势研究

本文利用IGS全球分布的连续运行站研究了地壳运动趋势。首先利用线性拟合计算了各运行站的高程方向线性速度,然后利用求得的线性速度计算了不同纬度的闭合环纬线变化率。结果表明,地壳各点运动趋势既不均衡也不对称;南半球闭合环纬线变化率全部为正值,说明南半球纬线圈处于拉伸状态,反映南半球整体膨胀趋势;北半球变化率有正有负,说明北半球整体变化趋势不明显。通过分析得出地壳存在非对称运动趋势的结论。     

浙江省分钟降水自记纸信息化数据与人工读取数据的对比及适用性分析

为了探讨信息化分钟降水自记纸数据在短历时时段下的适应能力,对比评估了1980-2000年浙江省19个国家基本（准）站信息化后的分钟降水自记纸数据和同期人工读取降水数据。利用滑动求和的方法提取信息化分钟降水不同历时下每年最大降水量,并使用偏差百分率、方差比、偏差概率、相关分析等统计方法,对比分析了信息化后的分钟降水自记数据与人工读取数据的时空特征差异及信息化数据的适用性。研究结果表明：信息化后的分钟降水数据与人工观测数据的结果在整体及单次降水过程中的表现较为一致,数值上整体略偏小,相关系数达到0.99。30min以上历时信息化后分钟数据与人工校核数据非常接近,且稳定性很高。信息化后分钟数据计算结果比人工读取结果更为客观,可以较好地代替人工读取结果的同时,有效地弥补了自动气象站建站之前逐分钟降水资料记录的空缺,为计算暴雨强度公式、设计暴雨雨型等需要长时间序列分钟降水的研究工作奠定了基础。     

A comparison of landslide rates following helicopter and conventional cable-based clear-cut logging operations in the Southwest Coast Mountains of British Columbia

A comparison of landslide rates following helicopter and conventional, cable-based, clear-cut logging was carried out using results from two independent terrain attribute studies in the Eldred and Lois River watersheds in the Southwest Coast Mountains of British Columbia. Landslides initiating from directly within a road prism were excluded from the study in order to focus the comparison on landslides related primarily to conventional versus helicopter yarding methods. A landslide rate of 0.02 landslides/ha was observed in 162 terrain polygons logged by helicopter 8 years prior to this study. Landslide rates in 38 gullied polygons were 0.06 landslides/ha. No landslides were observed in 124 open-slope polygons. Over a similar 8-year average period, 0.03 landslides/ha were observed in 142 cable-yarded terrain polygons; 0.06 and 0.02 landslides/ha occurred in gullied and open-slope polygons, respectively. t-Tests indicate that total landslide rates are not significantly different following helicopter and conventional logging; however, a dichotomy exists between gullied and open-slope terrain polygons. Landslide rates are not significantly different in gullied terrain but are significantly higher on open-slopes following conventional cable logging. Consequently, landslides appear to have a greater potential to occur in open-slope terrain following conventional logging, but differences in gullied polygons are less likely. Increased post-logging landslide rates in conventionally logged, open slopes are more likely the result of undetected road-related drainage changes than differences between helicopter and conventional yarding-related ground disturbance.     

Temporal variations in the concentration and settling flux of carbon and phytoplankton pigments in a deep fjordlike estuary

The weekly mass flux of C and phytoplankton pigments at five depths in the main basin of Puget Sound, a deep (200 m) fjordlike estuary, was sampled for a year with moored sequentially-sampling sediment traps. Flux measurements were compared with weekly samples of suspended pigments in the euphotic zone and bi-monthly samples of total suspended matter and particulate C throughout the water column at the mooring site.Seasonal changes in the total mass flux at all depths were small; instead, physical (river runoff, bottom resuspension) and biological (phytoplankton blooms) events caused occasional sharp increases on a weekly scale. The dry weight concentration of pigments in the trap samples mirrored the concentration of pigments in the euphotic zone suspended matter, increasing from 0·01% in winter to a maximum of 0·65% in late summer. Bloom-induced changes in the pigment concentration were observed almost simultaneously in the euphotic zone and in the traps to a depth of 160 m, indicating a rapid vertical transfer of surface-originating particles by organic aggregates. In contrast to the strong seasonal signal in the pigment concentration, C concentration varied by only a factor of three during the year.The seasonal trend of C/pigment ratios in the C flux arises from at least two sources: (1) a balance between terrestrial sources of C during the high-runoff winter season and in-situ primary production in spring and summer, and (2) cycling of C through the zooplankton population. Budget calculations suggest that the loss of primary-produced C and pigment from the euphotic zone by settling is 5% regardless of season. On an annual basis, this C flux (16 g m⁻²) is sufficient to support previously measured values of benthic aerobic respiration at the mooring site. To account for other C sinks such as burial, predation and chemical oxidation, however, terrestrial C sources and alternate transport pathways, such as vertical advection and sediment movement down the steep basin walls, are necessary.     

刺参夏眠不同时期划分以及前肠各组织层厚度定量分析

以非夏眠期刺参(Apostichopus japonicus)为对照组,在刺参夏眠不同程度选取3个时间点,将其分为夏眠初期、深度夏眠期、夏眠解除期3个阶段,采集前肠组织为研究材料,制作石蜡切片,统计不同时期刺参前肠壁厚度、前肠黏膜上皮、黏膜下层、肌肉层和外膜的厚度及直径.结果显示,与对照组相比,夏眠不同时期黏膜下层厚度均无差异(P＞0.05),夏眠初期黏膜上皮和外膜显著薄于对照组(P＜0.05),深度夏眠期黏膜上皮和肌肉层显著薄于对照组(P＜0.01),刺参前肠直径在深度夏眠期显著变小(P＜0.01).计算前肠各组织层占肠壁厚度的比例发现:夏眠初期黏膜上皮和外膜厚度占肠壁总厚度的比例要显著小于非夏眠期(P＜0.05),黏膜下层的比例则显著变大(P＜0.01),肌肉层所占比例在深度夏眠期显著小于其他几个时期(P＜0.05).     

油田开发中后期储层面临的问题与基于沉积成因的地质表征方法

随着中国已开发老油田进入高含水阶段,储层研究的核心发生了一定的转移,重点从优质储层的评价转向影响油藏注采矛盾的层内与平面储层非均质性。层内非均质研究的重点从传统的非均质参数评价转向储层构型研究,即针对不同沉积成因来研究砂体在不同方向上的几何形态与其内部隔夹层的展布特征;而平面非均质的研究则走进了依据储层规模、沉积成因及特点,尤其是岩性特征与其厚度的差异来选择合理的表征参数,并进行成因统计与定量编图的阶段;构成了"微相导向、相序指导、成因量化、平剖结合"的储层表征新方法,以便更好地体现储层表征的功能与作用,即识别不同储集体(对开发而言就是小层或单砂体)自身的成因特征与分布规律并依此来解决油田开发矛盾的作用。功能的核心就是科学地进行成因分类并最大限度地逼近地质的真实,而作用则是预测地下油气的分布规律并为其有效或高效开发提供可靠的系统指导。     

Strain-Rate Dependent Stress--Strain Behavior of Undisturbed Hong Kong Marine Deposits under Oedometric and Triaxial Stress States

This article presents a testing study on the strain-rate effects on the stress--strain behavior of natural, undisturbed Hong Kong marine deposits (HKMD) from three Hong Kong locations, including a one-dimensional (1-D) compressibility in a confined condition, and undrained shear strengths in triaxial compression and extension modes. The influences of the strain rates on the one-dimensional compressibility are studied by means of constant rate of strain (CRS) tests and multistage loading oedometer (MSL) tests, and those on the undrained shear strengths are studied by K_o-consolidated undrained compression and extension tests with step-changed axial strain rates (CK_oUC and CK_oUE tests), and with both step-changed axial strain rates and relaxation processes (CK_oUCR and CK_oUER tests). The strain-rate effects on the stress--strain behavior are generally examined by “apparent” preconsolidation pressures in the 1-D compressions and undrained shear strengths in the triaxial compression and extension stress states. The stress--strain behavior of the natural, undisturbed HKMD exhibits considerable viscous characteristics. In the CRS and MSL tests at a given strain, the higher the strain rate, the higher the effective stress, the higher the porewater pressure. In the undrained shearing tests, the higher the strain rate, the higher the undrained shear strength, but the lower the porewater pressure. For the CK_oUC and CK_oUE tests on the Tsing Yi site samples, the undrained shear strength increases by 8.5% and 12.1% for one order increment of axial strain rate of 0.2%/hr (i.e., ρ_0.2) for the compression and extension modes respectively. For the CK_oUCR and CK_o tests on the Tung Chung site samples of different compositions, average ρ_0.2 is increased by 6.2% for the compression and 9.5% for the extension, but by 18.8% for the extension on a higher plastic sample. The present study shows that the strain-rate effects on the stress--strain behavior of the undisturbed HKMD are larger for specimens in extension than those in compression.     

并置VLBI站相对形变率及其与VTRF2005结果的比较

对杨志根等人在2005年估计的全球6个并置VLBI站的相对形变率(特别是相对垂直形变率)结果与最近的VLBI全球解VTRF2005的相应结果作了比较。结果表明,北美Greenbank的NRAO20和NRAO85_3两个VLBI站之间每年3—4mm的相对垂直形变率和Westford的WEST- FORD和HAYSTACK两个VLBI站间每年1-2mm的相应结果可以进一步得到肯定;太平洋夏威夷岛的KOKEE和KAUAI两个VLBI站每年2～5mm的相对水平形变率和日本鹿岛的KASHIMA和KASHIM34两个VLBI站间每年1-2mm的相应结果也可以得到确认。然而,每年2—4mm的KASHIMA和KASHIM34站间的相对垂直形变率结果,在过去所有观测研究的结果中都被基本肯定,在VTRF2005中的结果中却几乎消失了,对其中可能的原因作了讨论。此外,对北美的FD-VL- BA和HRASO85两个VLBI站间的相对垂直形变率仍不能肯定,在不同的全球解中,FD-VLBA站的形变率解结果是基本稳定的,而HRASO85站在VTRF2005中的垂直形变率结果为(2．61±3．91) mm／a,与估计的结果符号相反,并且比在VTRF2003中的相应结果大了2．2mm／a,估计误差也大了近7倍。有关的结果还有待采用更新的资料进行讨论。     

Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous work.Aeolian sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground surface.Despite extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field observations.One key problem is a few of sufficient research on liftoff rates of saltating sand g...     

Microscale investigations of microbial communities in coastal surficial sediments

The upper millimeters of sediments are considered major locations of microbial colonization and activity. The goal of our study was to investigate variations of microbial communities in the uppermost sediment layers of the coastal Baltic Sea with emphasis on the complex interplay between microbiology and physico‐chemical sediment properties. We selected a high‐resolution methodological approach that combined the cryolanding sampling technique (spatial resolution of 250 μm) with microsensor‐, spectrophotometric and microscopic analyses. While the oxygen penetration depths in dark conditions ranged from 1.4 mm to 2.6 mm during the study period, this zone expanded by about 1 mm in light and could be divided into three micro‐horizons: (i) an upper zone with a high net O₂ production, (ii) an intermediate zone with increased O₂ consumption on account of light‐stimulated respiration and (iii) a lower zone with lower O₂ consumption. Time‐series experiments revealed a rapid response of the benthic microbial community to altered light intensities. In May and July, the net O₂ budget in the porewater of sediments was positive within 35 and 22 min after illumination, respectively, whereas in June O₂ production exceeded O₂ consumption after 112 min. The thickness of the O₂ production and O₂ consumption micro‐zones decreased from May to July coinciding with an increase in temperature. In May, sites of enhanced O₂ consumption were closely associated with subsurface maxima of microbial numbers and enzymatic activities indicating a tight coupling between photoautotrophic and heterotrophic processes between 1‐ and 2‐mm depth. In June and July, the microbial abundance and enzymatic activity hardly varied with depth. Spatial and temporal microheterogeneity of microbial distribution and activity in O₂ gradients was seen as a reflection of the complex interplay between microbiology and physico‐chemical sediment properties.