纳米硅粉水泥土的强度特性及固化机理研究   总被引：8，自引：0，他引：8  

王文军  朱向荣 《岩土力学》2004,25(6):922-926

将性能优异的纳米硅粉作为外掺剂应用于水泥土改性研究。通过室内试验，探讨了纳米硅粉水泥土的强度特性。试验表明，一定掺量下的纳米硅粉能够显著提高水泥土的各个龄期强度。结合试验测试和理论分析，探讨了纳米硅粉在水泥水化硬化过程中的作用以及纳米硅粉与土之间的作用，在此基础上，分析了纳米硅粉改性水泥土工程性状的机理，旨在为纳米硅粉应用于工程实践开展理论和试验研究探索。  相似文献   

方石英的亚稳态形成机制探讨   总被引：3，自引：0，他引：3  

肖万生  陈晋阳  彭文世  翁克难 《矿物岩石》2003,23(4):5-10

方石英形成于石英或鳞石英热力学稳定区是一种普遍的现象，并基本上是由非晶态SiO2转变而成。方石英的这种亚稳态形成机制可用Ostwald分步规则这一动力学经验规律来阐述；而引起非晶态SiO2转变成方石英的速率常数大大高于方石英转变成石英或鳞石英的速率常数的本质是非晶态SiO2局部中程有序结构与β—方石英的动态无序结构的相似性；这种相似性使非晶态SiO2结晶过程中β—方石英的有效成核速率大大增加，并最终导致亚稳态方石英的形成。非晶态SiO2中所含的杂质元素有利于降低方石英的形成温度，加速反应进程，但对于亚稳态方石英的形成没有决定作用，除非这些杂质元素有利于方石英结构的稳定性。  相似文献   

硅胶／壳聚糖吸附材料的制备及表征     

张玉玉  王以明  蔡国军 《地质灾害与环境保护》2008,19(3):109-112

利用γ-氨基丙基-三乙氧基硅烷偶联剂与活化硅胶表面的羟基反应,制备了硅烷化硅胶,所得产物与壳聚糖反应合成了硅胶／壳聚糖复合吸附材料。通过红外光谱分析（IR）,扫描电镜（SEM）及能谱分析对复合材料进行表征,并测试了硅胶／壳聚糖复合材料对Zn^2＋、Cd^2＋的吸附能力。结果表明：复合吸附材料对Zn^2＋、Cd^2＋具有很好的吸附能力,最大吸附率为96．01％及90．65％。  相似文献   

Sedimentary records of eutrophication in the Changjiang Estuary upwelling area over last 100 a   总被引：3，自引：1，他引：2  

FENG Xuwen  JING Xianglong  YU Xiaoguo  LI Hongliang  CHEN Jianfang  QIAN Jiangchu 《海洋学报(英文版)》2008,27(6):49-61

The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi） and stable organic carbon isotopic ratios（δ13 Corg） were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation （TOC, TN and BSi） was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.  相似文献   

The use of sedimentary algal pigments to infer historic algal communities in Lake Apopka,Florida   总被引：1，自引：0，他引：1  

Matthew?N.?WatersEmail author  Claire?L.?Schelske  William?F.?Kenney  Andrew?D.?Chapman 《Journal of Paleolimnology》2005,33(1):53-71

The primary producer community of Lake Apopka, a large (125 km²), shallow (mean depth, 1.7 m), polymictic Florida lake, shifted from macrophyte dominance to phytoplankton dominance in the 1940s. Today, frequent wind resuspension of highly organic, unconsolidated sediments supports a meroplanktonic community that is predominantly diatoms, but during calm periods the algal community is dominated by planktonic cyanobacteria. Sedimentary algal pigments (chlorophyll derivatives and carotenoids) and chemical proxies for nutrient enrichment (polyphosphate, total phosphorus and biogenic silica) in three sediment cores were used to investigate historic changes in primary producers. Sediments were separated into three stratigraphic zones using multivariate statistical techniques. Stratigraphic zonation was established in each core although sediment deposition at one site was insufficient to adequately resolve temporal changes. These results show the importance of selecting suitable sites for paleolimnological studies. The oldest zone represents macrophyte-derived sediments, and the two overlying zones represent phytoplankton-derived sediments deposited since the 1940s. Algal pigments in the most recent sediment zone show little degradation, which might be due to the presence of viable meroplankton in the sediment. After the initial primary producer shift from macrophytes to phytoplankton, the lake experienced a short period of cyanobacterial dominance followed by a period of benthic diatom abundance before being replaced by the present algal community consisting of cyanobacteria and meroplanktonic diatoms. Chlorophyll derivatives and carotenoids were highly correlated with total phosphorus. Historic trends inferred from the data include algal and cyanobacterial productivity that increased with increased phosphorus loading. The study demonstrates that valid paleolimnological proxies for historic eutrophication are available in loosely consolidated sediments of shallow, subtropical lakes.  相似文献   

Modelling the OH stretch envelope shape and temperature effects in infrared spectra of hydrous silica and silicate glasses     

D. P. Zarubin 《Physics and Chemistry of Minerals》2000,27(8):590-597

Simple model calculations show that the reversible temperature effects reported for broad OH-stretching bands in infrared spectra of silica, aluminosilicate, and similar glasses can be explained, in essentials, by homogeneous thermal broadening of the ν(OH) envelope constituents and a decrease in intensity with increasing temperature taking place uniformly across the band. This means that these effects are reasonably consistent with the temperature behaviour of narrow ν(OH) bands of crystalline OH-bearing minerals. These findings leave little room for the previously agreed interpretation in terms of a change in hydrogen-bonding strength, although the dependence of integrated intensity on temperature still remains to be understood. Received: 16 April 1999 / Accepted: 4 April 2000  相似文献   

砂岩中石英胶结物的成因及其研究意义   总被引：6，自引：0，他引：6  

于均民  周晓峰  刘立 《世界地质》2000,19(1):20-25

次生加大石英胶结物是砂岩中最的胶结物之一。石英胶结物的时空分布表现在越年轻的地层石英胶结物的含量越少,随埋深增加石英胶结物的含量增加,而且盆地类型也是控制石英胶结物含量的一个不可忽视的因素。石英胶结物的硅质来源有很多种说法,但是区域上可能以某一种或某几种来源为主。影响石英胶结物沉淀的主要因素有温度流体的ｐＨ值等;而关于孔隙流动与硅质搬运和沉淀有三促假说,即：浅部地下水循环说、压实驱动流体高度集中说  相似文献   

西太平洋马尔库斯-威克海山区沉积物中生物硅含量分布          下载免费PDF全文

孟凡盛  倪建宇  姚旭莹 《海洋学研究》2019,37(4):60-67

分析了大洋40航次在西太平洋马尔库斯-威克海山区山间海盆采集的表层沉积物中生物硅和有机质的含量,并对其分布特征和来源进行了初步的研究。结果表明,马尔库斯-威克海山区附近海域深海表层沉积物中生物硅含量总体较低,含量在0.88%～12.41%之间,平均含量为2.19%,分布上呈现西南含量高,向东北方向递减的趋势;深海表层沉积物中有机碳含量较低,δ¹³C同位素组成分布与生物硅相同。沉积物柱状样的研究表明研究区在过去的100～200 ka期间表层水体中硅质生物的初级生产力是逐渐增加的。  相似文献   

乌江流域水库沉积物中生物硅的测定方法及其环境意义   总被引：1，自引：0，他引：1  

雷云逸  汪福顺  陆丹萍  梅航远 《矿物学报》2011,31(1):30-35

采用碱提取法中的单点法与多点法相结合,测定了乌江流域水库沉积物中生物硅的含量,并对多点提取法进行了改良。采用多个离心管分装定量样品进行连续振荡,每小时提取1个样品进行测定。对多个时间点的提取结果,利用线性回归法分析得出最佳提取时间,优化最佳提取液,然后利用单点提取-硅钼蓝检测法测定沉积物中生物硅的含量。该方法既保证了单点法的快速,也减小了多点法的多次提取操作与提取时的体积误差。本文根据测定结果探讨了乌江流域水库沉积物中生物硅含量变化规律及其环境意义。  相似文献   

北极新奥尔松地区土壤中生物硅含量及形态特征          下载免费PDF全文

刘森冉祥滨  臧家业王能飞 《极地研究》2015,27(3):237-245

硅循环与碳循环密切相关,生物硅作为硅的重要载体,在全球硅循环中占有十分重要的地位。目前,人们对陆地生态系统的硅循环做了大量研究,但对极地地区硅的研究却极为少见。利用中国第五次北极考察获得的土壤与植物样品,对北极新奥尔松地区中国黄河站站基表层土壤中生物硅的含量及土壤和植被中生物硅(主要为植硅体)的形态进行了初步研究。主要结论为:北极新奥尔松地区中国黄河站站基附近表层土壤中颗粒有机碳的含量为1.00—69.3 mg·g-1,平均值为13.7 mg·g-1;颗粒有机氮含量为0.11—9.84 mg·g-1,平均值为1.43 mg·g-1;可溶态硅含量为3.90—26.3μg·g-1,平均值为10.7μg·g-1;生物硅含量为5.60—9.97 mg·g-1,平均值为7.56 mg·g-1,且其含量与土壤颗粒态有机碳和颗粒有机氮呈正相关关系,表明三者具有相似来源。北极表层土壤生物硅比温带、热带地区生物硅含量要高。植物样品中植硅体形态以帽形、圆形、平滑棒形、齿形、刺棒形和哑铃形等形态为主,大小在10—100μm之间。土壤样品中的植硅体主要来源于植物,形态分别为平滑棒形、刺棒形、圆形、哑铃形、鞍形、尖形和帽形,另外硅藻也是北极土壤中生物硅的组成部分,其中裸露土壤中藻类(羽纹纲硅藻)占生物硅的多数(93.3%)。对比发现,有植被覆盖的土壤中,土壤有机碳、可溶出态硅、生物硅含量和植硅体形态丰富度往往比无植被覆盖或寡植被区土壤高,这表明尽管该地区植被稀少,但植物生长对该地区土壤硅循环存在显著影响,值得进一步关注。  相似文献