天山北坡天然草场牧草干旱指标研究     

梁云  孙长东 《干旱区地理》1998,21(4):68-73

通过降水,土壤水分,天然草场产草量之间建立的统计关系,来说明水分供应是影响牧草产量的重要因素,并依据降水和土壤水分与牧草产草量的关系划分出牧草生长中水分供给的正常,干旱等指标。  相似文献   

塔里木盆地天然气运聚系统与运聚模式   总被引：7，自引：0，他引：7  

柳广弟  周兴熙 《沉积学报》1998,16(1):58-63

对塔里木盆地东部地层压力结构和天然气性质差异的研究表明,塔里木盆地东部具有多个独立的天然气运聚系统。这些运聚系统具有流体封存箱的特征。天然气只能在运聚系统内部进行短距离的运移,不能进行大规模侧向运移。因此天然气藏的形成具有近源的特点。由于不同运聚系统特征的差异,塔里木盆地大致有三种天然气运聚模式。  相似文献   

硫酸盐渍土在多次冻融循环时的盐胀累加规律   总被引：10，自引：3，他引：7  

褚彩平 《冰川冻土》1998,20(2):108-111

通过室内模拟试验,研究了硫酸盐渍土在历经多次冻融循环时的盐胀累加规律,得出了盐胀累加的不同类型,给出了累加盐胀率与循环次烽之间的关系式,进一步揭示了盐胀累加的 和影响因素。  相似文献   

基于土壤侵蚀遥感调查的河流输沙量的计算     

陈曦川  钟邵南 《水文》1998,(6):14-18

河流泥沙来量的计算是工程水文计算的一个重要组成部分。有水文站观测资料的地方,输潲星的计算比较容易。而对于没有水文站分布或观测资料不足的边远地区,用常规无法计算出输沙星。  相似文献   

南昆铁路新型、轻型支挡结构的设计与施工          下载免费PDF全文

李海光  魏永幸 《探矿工程》1998,(1):7-10

介绍了南昆铁路应用的各种新型,轻型支档结构及其设计与施工经验,并论述了适用条件。  相似文献   

土壤水全时空调控的初步探讨   总被引：3，自引：1，他引：2  

靳孟贵  赵万林 《水文地质工程地质》1998,25(1):47-50

农业是第一用水大户,有利利用土壤是实现黑龙港地区农业可持续发展的关键,本文分析了黑龙港地区主要作物需水与降水的关系,建立了作物生长条件包气带流动系统的概念,并以此为基础提出了土壤水全时空调控的概念,探讨了土壤水全时空调控的涵义与措施,指出土壤水调控是一系统工程,必须多种措施有机结合,简单介绍了王瞳试验场开展的田间土壤水调控试验成果。  相似文献   

活动断裂带的壤中气汞量测量研究   总被引：2，自引：0，他引：2  

刘树田  邓金宪 《地质论评》1998,44(5):547-552

在覆盖区应用壤中气汞量测量研究活动断裂是一种新方法,它不仅能较准确地确定活动断裂的位置,还可以确定其产状,规模,活动性及相对强度,甚至可以作为确定断裂力学性质的参考,本文简棕了断裂带壤中气汞量测量的基本原理,并以长江三峡,长春,吉林等地利用该种方法研究活动断裂的成果为例,说明该项研究的效果及应用前景。  相似文献   

Mobility of Al, Co, Cr, Cu, Fe, Mn, Ni and V in sulphide-bearing fine-grained sediments exposed to atmospheric O2: an experimental study   总被引：1，自引：0，他引：1  

Mats Åström 《Environmental Geology》1998,36(3-4):219-226

 The major aim was to increase our knowledge on the behaviour of Al, Co, Cr, Cu, Fe, Mn, Ni and V in sulphide-bearing fine-grained sediments exposed to atmospheric oxygen. Samples of this type of sediment collected in a previous investigation at eight sites in western Finland were digested in HClO₄-HNO₃-HCl-HF at 200  °C and in HCl:HNO₃:H₂O at 95  °C (aqua regia), and subjected to extractions with ammonium acetate and hydrogen peroxide. Metals and S in the leachates were determined with ICP-AES. The results of the chemical analyses are compared with previously reported experimental data. The concentrations of Al and Fe in the sulphide-bearing fine-grained sediments are about 7% and 5%, respectively. Of the trace metals studied, Mn is most abundant followed in decreasing order by V>Cr>Ni>Cu>Co. On oxidation of the sediments, high proportions of Co, Mn and Ni, intermediate proportions of Cu but low proportions of Fe, Al, Cr and V are released. The extent of the release of a metal on oxidation is controlled either by (1) the level to which the pH of the sediments drops on oxidation (Al, Cu, Cr, V), (2) the amount of the metal associated with easily reduced phases (metal sulphides) in the sediments (Ni, Co) or (3) the sum of the amount associated with reduced phases and adsorbed on soil compounds (Mn). No control of the release of Fe on oxidation of the sediments was identified. Based on the results of the study it is argued that artificial drainage and the subsequent oxidation of sulphide-bearing sediments will result in extensive leaching of Co, Mn and Ni, moderate leaching of Cu and limited leaching of Cr and V into drainages. The major elements, Fe and Al, have the potential to be mobilised and leached in large amounts, though the proportions mobilised/leached will remain low. It is suggested that the identification of sulphide-bearing sediments with a high potential of metal release should be based on determination of metals in easily mobilised reduced compounds (dissolved e.g. in H₂O₂) and of the level to which the pH of the sediments drops on oxidation. Received: 16 October 1997 · Accepted: 9 March 1998  相似文献   

The recent history of erosion and sedimentation on the Southern Tablelands of southeastern Australia: sediment flux dominated by channel incision   总被引：2，自引：0，他引：2  

R.J Wasson  R.K Mazari  B Starr  G Clifton 《Geomorphology》1998,24(4):291-308

As in other regions colonised from Europe within the last few centuries, Australia's vegetation and soils have been dramatically changed by clearing, cropping and grazing. In southeastern Australia, particularly on the Southern Tablelands, the impacts of European settlement are clearly manifested by channel incision. By using stratigraphic and documentary evidence, in conjunction with aerial photographs, sediment budgets for the post-settlement period have been constructed to define the fluxes and stores of sediment for each of the major geomorphic components of the 136 km² catchment of Jerrabomberra Creek near Canberra. Using these budgets, and some plausible assumptions, it has been possible to approximate the history of both the sediment delivery ratio and sediment yield for this catchment. While the quantities estimated in this analysis are approximations, the trends through time are credible. Sediment yield increased rapidly to a peak after European settlement, and has returned to a level between the peak and the pre-European value. The delivery ratio has followed a similar trend. The most general conclusion to emerge is that in this landscape both the total sediment flux and the sediment yield of the catchment have been dominated by channel erosion. This result is contrary to the findings in many parts of the world where sheet and rill erosion dominates the fluxes. The soil conservation implication of these results is clear: to control off-site effects of erosion, the focus must be on the channels.  相似文献   

Sex expression and growth rates in natural populations of the desert soil crustal mossSyntrichia caninervis     

Lloyd R. Stark  Brent D. Mishler  D.Nicholas McLetchie 《Journal of Arid Environments》1998,40(4):401-416

The low elevation Mojave Desert cryptobiotic crust is dominated by the mossSyntrichia caninervis. In 16 populations of this moss, stem height and population were significantly associated with sex expression, with longer stems expressing sex more frequently and producing more perichaetia. The above-ground age of stems ranged up to 10 years, with a mean growth rate across populations of 0.36 mm year⁻¹. The overall stem sex ratio, as a proportion of the total number of stems, was 0.30♀: 0♂: 0.70 non-expressing. The probability of expressing sex in a given season was 0.09. The absence of sexual reproduction (no sporophytes) and likely absence of the male sex from the area indicate that the non-expressing plants are female individuals. The slow growth rates, low rates of sex expression, absence of male plants, and absence of sexual reproduction in this crustal species may help explain why re-establishment of mosses on desert soils can take decades.  相似文献