Spectrophotometric Determination of Cationic Surfactants Based on Their Effect on the Complexes of Chrome Azurol S with Be2+ and Al3+ Cations     

Abbas Afkhami  Davood Nematollahi  Tayyebeh Madrakian  Mitra Hajihadi 《洁净——土壤、空气、水》2011,39(2):171-176

Simple, rapid, and sensitive spectrophotometric methods have been proposed for the determination of cationic surfactants (CS) as cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium (DTAB), and cetylpyridinium bromide (CPB). The methods are based on the effects of CSs on the complexes of Al³⁺ and Be²⁺ with Chrome Azurol S (CAS). The optimum reaction conditions such as CAS concentration, metal ion concentration, and pH have been studied and found to be 2.0 × 10^?4 mol L^?1 CAS, 0.5 mg L^?1 Al³⁺ or 0.4 mg L^?1 Be²⁺ and pH 5.4. The analytical characteristics of the methods such as limit of detections, limit of quantifications, and linear ranges have been obtained. CTAB, CPB, and DTAB could be determined by the Al–CAS complex in the ranges of 0.50–40.00, 0.20–10.00, and 0.40–10.00 µmol L^?1, and for the Be–CAS complex in the ranges of 0.08–5.00, 0.08–3.00, and 0.20–6.00 µmol L^?1, respectively. The limit of the detections of the method for the determination of CTAB, CPB, and DTAB for the Be–CAS complex has been found as 0.025, 0.024, and 0.061 µmol L^?1, respectively. The interfering effect of some anions and cations was also tested. The method was applied to the determination of CS CTAB in conditioner shampoo and water samples.  相似文献   

Chemical characteristics of chromian spinel in plutonic rocks: Implications for deep magma processes and discrimination of tectonic setting   总被引：2，自引：0，他引：2  

Shoji Arai  Hidenobu Okamura  Kazuyuki Kadoshima  Chima Tanaka  Kenji Suzuki  Satoko Ishimaru 《Island Arc》2011,20(1):125-137

We summarize chemical characteristics of chromian spinels from ultramafic to mafic plutonic rocks (lherzolites, harzburgites, dunites, wehrlites, troctolites, olivine gabbros) with regard to three tectonic settings (mid‐ocean ridge, arc, oceanic hotspot). The chemical range of spinels is distinguishable between the three settings in terms of Cr# (= Cr/(Cr + Al) atomic ratio) and Ti content. The relationships are almost parallel with those of chromian spinels in volcanic rocks, but the Ti content is slightly lower in plutonics than in volcanics at a given tectonic environment. The Cr# of spinels in plutonic rocks is highly diverse; its ranges overlap between the three settings, but extend to higher values (up to 0.8) in arc and oceanic hotspot environments. The Ti content of spinels in plutonics increases, for a given lithology, from the arc to oceanic hotspot settings by mid‐ocean ridge on average. This chemical diversity is consistent with that of erupted magmas from the three settings. If we systematically know the chemistry of chromian spinels from a series of plutonic rocks, we can estimate their tectonic environments of formation. The spinel chemistry is especially useful in dunitic rocks, in which chromian spinel is the only discriminating mineral. Applying this, discordant dunites cutting mantle peridotites were possibly precipitated from arc‐related magmas in the Oman ophiolite, and from an intraplate tholeiite in the Lizard ophiolite, Cornwall.  相似文献   

干旱区典型绿洲耕地扩张及其人文驱动研究——以新疆且末绿洲为例     

迪力夏提·阿卜杜萨拉木  阿不都克依木·阿布力孜  周玄德  许仲林  瓦哈甫·哈力克 《地域研究与开发》2015,(2):131-136,176

近年来,在全国耕地面积持续减少的背景下,西北干旱区耕地呈扩张趋势,现有研究关注其自然因素驱动力,对人文因素驱动力,特别是灌溉设施和方式、政策、经济利益和市场导向等因素关注较少。选取干旱区典型绿洲——且末绿洲,采用最大似然法和人机交互式分类相结合的方法从1972,1990,2001,2011年影像中提取耕地信息,结合统计学方法分析且末绿洲耕地变化的时空趋势、耕地复种指数的动态变化;在充分考虑人口因素的前提下,增加灌溉设施和方式、政策、经济利益和市场导向等因素,探讨了绿洲耕地扩张的人文驱动力。研究结果表明:1970年以来,且末绿洲耕地面积时增时减,总体呈增长趋势;耕地复种指数波动上升;人口增长、灌溉设施和方式、政策、经济利益和市场等因素在不同阶段以不同方式影响着该绿洲耕地面积的扩张。政策、经济利益和市场因素是近10年绿洲耕地迅速扩张的主要驱动因素。  相似文献   

绿洲发展的水资源总供给与总需求模型   总被引：6，自引：0，他引：6       下载免费PDF全文

杨海镇  马海州  沙占江  曹广超  欧立业 《盐湖研究》2004,12(1):51-56

从绿洲发展的主要制约因素———水资源的总供给与总需求出发,建立了绿洲发展水资源的总供给模型、总需求模型以及总供给—总需求模型,并以此来阐述我国西北干旱地区不同绿洲的发展状况以及同一条内陆河流域上、中、下游绿洲所存在的问题。  相似文献   

民勤绿洲生态重建目标下土地利用和农业结构调整的政策选择   总被引：3，自引：1，他引：2  

石敏俊  陶卫春  赵学涛 《干旱区地理》2009,32(2)

水资源过度利用引起的土地退化日益威胁着绿洲地区的经济社会可持续发展.为恢复绿洲生态环境,压缩农业用水势在必行.然而压缩用水后如何保障农民收入成为实现可持续发展的关键问题之一.应用Bio-economic模型,定量模拟了压缩农业用水后农户对土地利用和农业结构调整、推广节水技术、增加非农就业机会等政策措施的行为响应.结果显示,压缩农业用水后农民收入将下降到压缩前的53%;调整农业结构、推广闸管灌等节水灌溉技术和增加非农就业机会,可以在不同程度上缓解压缩农业用水造成的农民收入损失.不同区域农户响应行为有所差异,应因地制宜地采取配套措施.劳动力相对紧张、人均收入较高的泉山区,可提供一次性补贴鼓励闸管灌的采用;人多地少、集约化程度较高的坝区,应在加强推广闸管灌技术的同时,增加非农就业机会;生态脆弱的湖区,政策重点应放在劳动力转移上.上述措施最终只能使农民收入恢复到压缩用水前的75%,因此应该考虑给农民提供生态补偿,并积极探索增加农民收入的新途径.  相似文献   

Influence of environmental, root, and stand parameters on soil surface CO₂ efflux in a Populus euphratica of desert forest in extreme arid region     

ZongQiang Chang  Qi Feng  YongHong Su  JianHua Si  HaiYang Xi  ShengKui Cao  Rui Guo 《寒旱区科学》2009,1(4):0348-0355

Spatial variation in soil surface CO2 efflux was measured in a stand of Populus euphratica in the Ejina Oasis of desert riparian forest in the extreme arid region in northwestern China from April 2007 through October 2007.Measurements were taken with a gas-exchange analyzer linked to a soil-respiration chamber.The mean soil CO2 efflux in the stand was 2.71 μmol/(m2·s) during the growing season and 1.38 μmol/(m2·s) in the nongrowing season.The seasonal maximum (end of May through early June) andminimum (October) CO2 efflux were 3.38 and 0.69 μmol/(m2·s),respectively.The diurnal fluctuation of CO2 efflux was relatively small (< 20 percent),with theminimum appearing around 05:00 and the maximum around 15:00.Linear regression analysis showed soil-surface CO2 efflux to be most highly correlated with soil temperature (R2=0.435) and soil moisture (R2=0.213).When all variables were considered simultaneously,only soil temperature (R2=0.378),soil moisture (R2=0.147),and root volume density (R2=0.021) explained a significant amount of variance in soil surface CO2 efflux.Stand volumes were not correlated with soil CO2 efflux on our sites.  相似文献   

对绿洲概念本质特征的思考   总被引：1，自引：1，他引：0  

周跃志  常顺利 《中国沙漠》2009,29(6):1169-1172

遵循发生学认识论和方法,就绿洲概念研究的“中心问题”进行了分析探讨。通过对绿洲的景观特征与生产力特征之间的关系分析,提出绿洲概念研究的“中心问题”是绿洲的景观特征与生产力特征二者的关系,而不是这两个特征本身,更非片面地或简单地强调这两个特征中的某一个;生产力特征是绿洲在功能上具有决定性作用的本质特征,景观特征是在结构上具有辅助性作用的表象特征。因此,科学的绿洲概念应该体现出这一点。  相似文献   

奥地利Gosau群Bibereck组Campanian早期海水变深序列的地层学和地球化学     

Michael WAGREICH  Stephanie NEUHUBER 《地学前缘》2005,12(2):0-0

Schmidsippl剖面位于奥地利北钙质阿尔卑斯构造带内Gosau群典型地区。剖面出露的Bibereck组记录了一个海侵和沉积区海水变深过程。Bibereck 组之下是Santonian 晚期Hochmoos 组(Sandkalkbank段),主要为砂质、粉砂质灰色生物扰动构造发育的泥灰岩,含少量双壳类碎片。Hochmoos组之上为灰色泥灰岩和泥灰质灰岩。Bibereck组下部显示变深到近滨-远滨过渡带区域;向上,泥灰岩指示细粒泥质远滨沉积,水深大致50~150 m;之上出现浮游有孔虫含量超过90%的泥灰质灰岩,代表着半深海沉积环境。生物地层数据显示采样层位整体位于浮游有孔虫asymetrica elevata 带,由Globotruncanita elevata 和Dicarinellaasymetrica 的共同出现来界定。钙质超微化石Calculites obscurus、Lucianorhabdus cayeuxii、Arkhangelsk iella cymbiformis 的出现指示属于钙质超微化石带CC17b/UC12,相当于Campanian初期。地层深度剖面上,Ca/Al比值和Catot含量显示海水来源的Ca在0~5 m地层内几近于零,向上快速增加;(Fe/Al)/碳酸盐显示两个峰值,代表更还原条件,分别位于4 m和10 m位置;K/Al比值的下降被解释为更潮湿气候条件;剖面上部Ba含量的增加显示向更低原始生产条件的变化;陆源矿物在剖面7 m以下保持稳定,之上一直到剖面顶部不断下降。生物地层  相似文献   

新疆三工河绿洲土地利用变化系统动力学仿真   总被引：12，自引：1，他引：11  

汤发树  陈曦  罗格平  蔺卿  李照杰  赫静 《中国沙漠》2007,27(4):593-599

从小区域(乡域)尺度出发,综合考虑人口、经济、技术、市场等主要人文因素对绿洲土地利用变化的驱动作用,建立系统动力学（SD）模型,并以天山北麓三工河流域为例,用1978—1998年的实际数据验证了模型的适用性和可靠性,在此基础上,模拟和分析了三种发展模式下本区域1998—2050年土地利用变化过程,结果表明：SD方法对于乡域尺度的土地利用变化研究是适宜的;三种模式下土地利用变化规律表现出明显的差异性,人口、经济、技术、市场等因素对本区域土地利用变化具有显著驱动作用。  相似文献   

26Al/10Be埋藏测年及其在洞穴沉积年代学研究中的应用     

邵庆丰  高斌 《中国岩溶》2006,25(3):195-200

长期暴露于地表的石英砂被快速搬入洞穴或埋藏,不再接受宇宙射线辐射,埋藏前所积累的陆地宇生核素26 Al 和10 Be 随时间指数衰减。据此用加速器质谱计测定沉积物中石英样品现存的26 Al /10 Be可计算其埋藏年代。用此方法本文对周口店第一地点的下部地层年代作了初探。此次研究表明自第10层以下的沉积物其年代很可能≥ 1 Ma。   相似文献