Fluctuation in the zooplankton community in two solar salt ponds,Aveiro, Portugal     

N. Vieira  F. Amat 《International Journal of Salt Lake Research》1995,4(4):327-333

The zooplankton of two salt ponds at Aveiro was studied to evaluate its density and diversity. Samples were collected biweekly from the salt ponds Esmolas and Tanoeiras. Samples were first separated into Holoplankton (Copepoda, nauplii,Acartia, Ostracoda and Anostraca) and Meroplankton (Mollusca, Insecta, annelidan larvae and Ichthyoplankton). The Holoplankton was mainly composed of:Acartia tonsa, Acartia sp.,Eurytemora velox, Artemia sp., and harpacticoids and calanoids. In both salt ponds, species diversity was identical, but total zooplankton density was higher in the Tanoeiras salt pond, probably because its physical and chemical characteristics allowed the development of stable communities.  相似文献   

Variability of sulfur along the coastal salt marshes, Quanzhou Bay, China     

《中国地球化学学报》2006,25(B08):11-11

  相似文献   

Experimental and numerical studies of rock salt strain hardening     

M. Hamami 《Geotechnical and Geological Engineering》2006,24(5):1271-1292

The work presented in this paper comes as part of a research program dealing with the thermomechanical behaviour of rock salt. It aims to study laboratory and in-situ long-term behaviour by means of creep tests with deviator and temperature changes. The laboratory results, using a triaxial multi-stages creep tests, highlighted the strain hardening character of rock salt. Furthermore, the in-situ results, using a borehole dilatometer multi-step creep test, have shown that the drilling is carried out in a weakly stressed pillar. The interpretation of the laboratory results, using the J.LEMAITRE law, did not indicate full agreement with all the test results. As a result a ‘double’ J.LEMAITRE model, which takes into account a double strain hardening variable, has been put forward. The validation of this model on the laboratory creep tests is very satisfactory. Furthermore, the activation energy seems satisfactory to represent the influence of the temperature. The in-situ behaviour modelling is clearly more complex than the modelization based on laboratory tests. In fact, it seems that if the rock salt behaviour is maintained by J.LEMAITRE law, it is necessary to vary with the stress, at least, one of the parameters assumed constant in the basic law.  相似文献   

图像平滑算法比较研究及改进策略   总被引：9，自引：0，他引：9  

秦志远 吴冰王艳  山海涛 《测绘学院学报》2005,22(2):103-106

图像平滑作为去除图像中含有噪声的图像增强处理技术，是各种与图像有关软件中必不可少的功能模块。文中在分析噪声模型的基础上，对均值平滑、中值平滑、边缘保持平滑等技术从图像处理空间域中的算法原理、实现方法及效率等方面进行了详细比较。针对图像中含有的不同噪声模型，通过多次试验，得出了值得从事图像处理研究者参考的结论。这将有助于提高图像处理软件开发的效率。  相似文献   

内陆盆地的盐分布与平衡分析研究   总被引：9，自引：0，他引：9       下载免费PDF全文

董新光  姜卉芳  邓铭江  周金龙 《水科学进展》2005,16(5):638-642

在总结已有研究成果和系统分析水文、土壤、灌溉、水盐监测资料的基础上,应用系统分析方法、水盐运移理论和水盐平衡原理,通过对盆地、流域、灌区、农田和土壤剖面等不同层次盐分分布与盐平衡分析计算,分析了内陆盆地不同层次的“干排盐”形成与特征,认为干排盐是必不可少的,必须系统地考虑不同层次干排盐出路与动力条件,才能有效地治理灌区盐渍化问题。  相似文献   

Evapotranspiration from citrus trees growing in sandy soilunder drip irrigation with saline water     

杨胜利  Tomohisa Yano 《中国科学D辑(英文版)》2002,45(Z1)

An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation.  相似文献   

钙贝塔石(Calciobetafite)在我国的发现     

张如柏  杜崇良  龙照云 《矿物岩石》2003,23(3):5-8

钙贝塔石发现于四川西昌的霓辉石-钠铁闪石脉中，与之共生的矿物是霓辉石，钠铁闪石，钠长石，铈磷灰石，硅钛铈矿，沥青铀矿，重晶石，方解石和彩钼铅矿等。钙贝塔石呈黑色，黑褐色，具八面体晶形，大小为2mm～8mm，条痕为黑色或黄褐色，油脂到沥青光泽，贝壳状断口。摩氏硬度为6．05～6．44(Hv=570．08kg／mm^2～689．06kg／mm^2)；无解理，比重4．51(扭力天平法测定)，反射率从406nm(13．53％)到659nm(11．87％)。经计算钙贝塔石的化学式为：(Ca，Na，U)2(Nb，Ti)2(0，OH)，。钙贝塔石的强X射线：2．975(10．222)，2．570(5．400)，1．816(9．440)，1．549(8．622)，1．050(6．844)，等轴晶系，α=1．029nm。  相似文献   

河南东濮凹陷古近系沙河街组盐岩沉积特征及成因   总被引：13，自引：6，他引：13       下载免费PDF全文

胥菊珍  蒋飞虎  张孝义  尹哲 《古地理学报》2003,5(2):162-170

东濮凹陷是渤海湾盆地的一个次级构造单元，其古近系的两个沉积旋回发育了四套盐岩，分别位于沙河街组第三段的第四亚段(S34)、第三亚段(S33)、第二亚段(S32)和沙河街组的第一段(S1)。主要分布在凹陷北部。每套盐岩又由若干个盐韵律组成，每一单韵律由盐岩和泥岩组成。两套等时对比标志层（深湖沉积）之间盐岩与砂泥岩存在着相变关系。盐岩是在深盆背景下干旱成因的，盐类物质来自地下深处上涌的卤水，分层卤水是盐形成的基本形式，上涌通道是基底大断裂，动力基础是岩浆活动。盐的阻隔作用使其对下部地层的温度、压力均有影响，这种影响有利于加快盐下地层中的有机质成熟与演化。盐又是良好的盖层，且在高温、高压下盐呈塑性状态。勘探实践看出东濮凹陷的岩性油气藏与盐岩的沉积有密切的关系，因此搞清盐岩的分布规律对东濮凹陷下步勘探有着极为重要的意义。  相似文献   

蒸发皿系数Kp计算方法研究   总被引：5，自引：0，他引：5  

周振民 《水文》2003,23(1):21-23

应用指标回归法和定性（风速和相对湿度）定量（吹程）资料，建立了蒸发皿系数Kp计算方程，并用黄河下游引黄灌区48个观测站实测资料进行了验证计算。计算结果表明，应用该方程，可大大改善Kp值的计算精度。  相似文献   

新疆盐渍土分散性研究     

杨昭  席福来  缪元勋  陈华  申联奇 《岩土力学》2003,(Z1)

通过研究分析盐渍土及改变盐渍含量对分散性试验的影响,认为土块试验、针孔试验对受高钠离子影响的盐渍土分散性评价是较为有效的方法。新疆土料石膏发育,环境水中Ca2+离子丰富,分散性评价最好在工程实际情况下进行。  相似文献