Influence of dimethylsulfide produced by marine algae on the global climate     

林荣根  刘新威 《中国海洋湖沼学报》1996,14(1):47-55

DMS (dimethylsulfide), a breakdown product of cellular solutes of many species of macroalgae andphytoplankton plays an important role in regulating global climate and counteracting partly the "greenhouse" effect.In this paper, the advance and prospects of DMS study are reviewed and discussed with respectto DMS sample storage, measurement and importance in regulating global climate and the acidity ofrain and aerosol.  相似文献   

地震学定量预报指标的一种提取方法——对比筛选法     

周翠英  蒋海昆  王红卫  姜早峰 《地震》1994,(4)

鉴于目前地震学综合定量预报指标的缺乏和预报工作的急需,尝试使用“对比筛选法(简称CSM方法)”进行地震学定量预报指标的提取试验。较之以往作法的进展在于:1.同时使用“有震”和“无震”两类样本对比筛选;2.对不同地区的地震学参数进行了归一化处理。这样做的显著优点是:1.可以较有效地提取“有震异常”和“正常变化”指标;2.提取的异常和预报指标具有定量化和普适性特点。 试验研究使用大华北地震区资料,研究对象取中强地震。经内符和外推检验,证明该方法提取的异常和预报指标有效性和实用性较高。  相似文献   

Effects of human activities on mercury in the environment in Xi＇an area, China     

Yongqing JIN Xiaojuan WANG Chengxiao ZHANG Julia LU Qingbo DUAN 《中国地球化学学报》2006,25(B08):239-240

Effects of mercury on ecosystems and human health are well documented. Human activities have significant impacts on transport, transformation, and fate of mercury in the natural environment. In this study, a gold mining area （Tongchuan）, an urban area （Xi＇an）, and a historical site （Qinshihuan Tomb） in Shaanxi Province, China, was chosen to study the effects of human activities on the transport, transformation, and fate of mercury in the area. Samples of atmospheric precipitate, soil, sediment, pomegranate, corn and those from wells and the rivers that flow through or flow by the city and from the mining area were collected. The EPA methods were used for sample preparation and analysis of these samples. These methods combine acid digestion, chemical reduction, purge and trap with Cold Vapor Atomic Fluorescence Spectrometry （CVAFS）. Preliminary results showed high total mercury concentrations in the water samples collected from a river in Tongguan County. The total mercury concentrations ranged from 133 to 188 ng/L in the water samples collected from the rivers flowing through Xi＇an City. The amount of total mercury in the soil/sediment samples which were collected in the vicinity of Xi＇an ranged from 31.8 to 83.2 ng/g. The total mercury concentrations in the samples of atmospheric precipitate （including rain and snow collected from Sep. 2005 to Jan. 2006） ranged from 106-298 ng/L.  相似文献   

Timing effects on the fragmentation of small scale blocks of granodiorite     

P. D. Katsabanis  A. Tawadrous  C. Braun  C. Kennedy 《Fragblast: International Journal for Blasting and Fragmentation》2006,10(1):83-93

A series of small scale tests, simulating multi-hole blasts have been performed to establish the effect of delays on blast fragmentation. The blasts were performed in high quality granodiorite blocks, which were cut from stone prepared by dimensional stone quarry operations. The pattern used was equilateral triangular, with a distance of 10.2 cm between boreholes, which had a diameter of 11 mm, were loaded with detonating cord and the coupling medium was water. The delays used were achieved using different lengths of detonating cord for the cases of delays between 0 and 100 μs between holes and a sequential blasting machine firing seismic detonators for larger delays up to 4 ms. All fragments were collected and screened. The experiments showed that the worst fragmentation was achieved with simultaneous initiation of all charges. Fragmentation improved with the delay time between holes up to 1 ms between holes. If the experiments are scaled up, the results show that in granodiorite, fragmentation optimization requires delays of few milliseconds per metre of burden. The findings, agree with previously published work, involving larger scale experiments and other rock types.  相似文献   

新近沉积粉细砂层地基的试验与评价     

赵本肖  游占军 《中国煤田地质》2006,18(4):45-46,48

通过对邯郸市某车间地基的勘察．分析和探讨了新近沉积粉细砂地层的勘察手段、其物理力学性质，及其利用载荷试验确定承载力的标准取得了较为满意的结果，提出的一些分析方法，对新近沉积的粉细砂地层的勘察具有一定的借鉴作用。  相似文献   

Site Investigation for the Effects of Vegetation on Ground Stability     

John R. Greenwood  Joanne E. Norris  Jo Wint 《Geotechnical and Geological Engineering》2006,24(3):467-481

The procedure for geotechnical site investigation is well established but little attention is currently given to investigating the potential of vegetation to assist with ground stability. This paper describes how routine investigation procedures may be adapted to consider the effects of the vegetation. It is recommended that the major part of the vegetation investigation is carried out, at relatively low cost, during the preliminary (desk) study phase of the investigation when there is maximum flexibility to take account of findings in the proposed design and construction. The techniques available for investigation of the effects of vegetation are reviewed and references provided for further consideration. As for general geotechnical investigation work, it is important that a balance of effort is maintained in the vegetation investigation between (a) site characterisation (defining and identifying the existing and proposed vegetation to suit the site and ground conditions), (b) testing (in-situ and laboratory testing of the vegetation and root systems to provide design parameters) and (c) modelling (to analyse the vegetation effects).  相似文献   

非等截面桩超声波成孔质量检测     

韩亮 《物探与化探》2005,29(2):185-188

分析了非等截面超声波成孔质量检测的几个主要影响因素,给出了相应得改进措施。用工程实例说明超声波反射技术是一种保证非等截面桩成孔质量和成桩质量必不可少的检测方法。  相似文献   

理学3080E3型X射线荧光光谱仪维修实例   总被引：2，自引：0，他引：2  

唐晓慧 《岩矿测试》2005,24(3):237-238

介绍理学3080E3型X射线荧光光谱仪样品驱动单元及高压发生器部分的故障现象及维修实例。  相似文献   

G-Probe-1 - An International Proficiency Test for Microprobe Laboratories - Report on Round 1 : February 2002 (TB-1 Basaltic Glass)     

Philip J. Potts  Michael Thompson  Stephen Wilson 《Geostandards and Geoanalytical Research》2002,26(2):197-235

Results are presented for round one of a new international proficiency testing programme designed for microprobe laboratories involved in the routine analysis of silicate minerals. The sample used for this round was TB-1, a basaltic glass fused and prepared by the USGS. Thirty nine laboratories contributed data to this round, the majority of major element results being undertaken by EPMA and the majority of trace elements by LA-ICP-MS. Assigned values were derived from the median of results produced by nine selected laboratories that analysed powdered material by conventional ICP-MS, INAA and XRF techniques using bulk powders of the sample. Submitted microprobe results were evaluated using a target precision calculated using the Horwitz function, adopting the same criteria as those used for "applied" geochemistry laboratories in the companion GeoPT proficiency testing programme for laboratories involved in the routine bulk analysis of silicate rocks. An evaluation of results from participating microprobe laboratories indicated that overall, data were compatible with this precision function. A comparison between the performance of bulk and microprobe techniques used in the analysis of the basaltic glass showed remarkably good agreement, with significant bias only observed for the major oxide MgO.  相似文献   

原子荧光光谱法测定地球化学样品中的砷、锑和汞的方法改进   总被引：1，自引：0，他引：1  

何贵  陈康林  王禄军 《四川地质学报》2003,23(1):62-64

在原子荧光光谱法中，通过改进地球化学样品的分解条件，预还原条件及测定条件，使砷、锑和汞能在同一介质中测定，而且实现了砷与汞的双道同时测定。方法的检测出限、准确度及精密度均能达到行业要求。  相似文献