326 resultados para 20-200


Relevância:

20.00% 20.00%

Publicador:

Resumo:

植物稳定同位素气候学因其具有坚实的理论基础,在古气候研究中倍受关注。同位素“语言”对气候变化的记录是一种“精确”记录。近30多年来,大量科学家不懈努力,提出并完善了植物C、H、O同位素分馏模型,为全球气候变化提供了理想的研究手段。古气候研究面临空前的机遇和挑战;不论是气候规律的发掘以及气候驱动机制的探讨,均需要大力加强。作者利用植物同位素气候学这一理想的研究“工具”,分别选取树轮和泥炭气候历史档案库作为信息载体,开展了中国全新世以来高分辨率、多时间尺度的气候信息综合辨识。我的工作表明:植物稳定同位素组成是理想的气候代用指标。树轮、泥炭档案库相结合,可以获得多尺度(年际、代际、百年以及千年时间尺度)、高分辨率气候信息,对于认识全球气候变化规律以及深入探讨全球气候动力学机制是十分重要的。1、安图红松树轮同位素气候代用记录研究(1)安图红松树轮同位素组成受多种气象因子的联合作用,因而单一地将某一同位素指标与某一气象因子做回归分析所得结果不甚理想。本论文构建了“温度一湿度”复合气候指标,取得了理想的结果。研究发现,不论是树轮δ13C还是δ18O,均与5-8月温湿复合指标显著相关。重建的气候变化与《安图县志》记录的气候变化事件大多吻合。证明这种新的研究方案是可行的,值得在以后的工作中进一步加强。(2)安图红松树轮δ13C灵敏地记录了该区过去200年来5-7月低云量变化。综合分析各种气象要素之间的相关关系以及气象要素与树轮δ13C之间的相关关系,作者认为,低云量对树轮δ13C的影响是一种间接影响。低云量非常显著地影响日照强度以及降雨量等气象因子,进而借助于日照强度及降雨量等气象因子在树轮δ13C中留下自身的变化“印记”。(3)功率谱分析证明,安图红松树轮δ13C、δ18O序列均包含了显著的准2年周期、准4年周期、准10-8年周期。分别是对东亚夏季风准两年振荡(QBO),ENSO准4年周期,太阳活动准11年周期的响应。(4)作者在传统树轮氢、氧同位素分馏模型基础上,同时引入“交换因子”和“蒸腾因子”两个新参数,改进了树轮氢、氧同位素分馏模型。改进的模型能利用树轮H、O同位素组成较准确模拟大气降水H、O同位素组成。改进的模型采用“自适应”方式,具有很大的灵活性,可望用于“用泥炭同位素组成模拟大气降水同位素组成”这项研究中。2、红原泥炭氧同位素气候代用记录研究(1)过去6000年来,红原温度变化趋势与金川、敦德温度变化趋势有很好的相似性,证明中国大多地区温度变化趋势是一致的。6000~4000aBP平均温度水平较低;4000-1500 aBP平均温度水平较高;1500aBP至今平均温度水平相对较低。4000aBP和1500aBP是近6000年温度变化序列中两个显著的转折点。(2)红原温度变化序列中记录到一系列低温突变,这些突变事件与金川、敦德、格陵兰、北大西洋,等等,广泛区域内温度突变事件具有很好的一致性。特别地,每当一次低温突变事件发生,通常有相应的社会结构重整、社会崩溃、古文明坍塌等重大历史事件与之对应。这进一步证实,气候变化(特别是气候突变)对整个社会经济和文明的冲击是十分明显的。(3)近6000年红原、金川温度变化趋势与大气14C变化趋势非常相似,暗示中国地区温度变化的主要驱动力来自太阳活动。功率谱分析进一步证实了这一结论。功率谱分析中最显著的周期信号是88-yr和123-127-yr年周期,体现了一种典型的世纪尺度温度变化特征。3、综合讨论(1)“红原-金川”平均温度变化趋势显示,近千年中国平均温度变化与经典的太阳活动极小期,如Darton极小、Maunder极小、sp6rer极小、oort极小,等等,表现一致。表明中国气温变化主要驱动力来自太阳活动。大约在1050-1250AD期间,中国温度水平较高。而同期大气14C,南极冰心10Be以及模拟的总太阳辐射等均表明太阳活动处于较高水平。大量树轮记录也表明近百年中国并无异常升温。这些资料表明,最近百年气温变化可能并未超出自然变率。(2)提出了“大洋温盐环流一季风”概念模型。这一模型能很好解释北大西洋温度突变与印度洋夏季风突变的一致性、中国东北和西南长期降雨趋势的反相性、北太平洋(温盐环流上翻区)温度记录与北大西洋温度记录的“跷跷板”效应(seesaw effect),等等。大洋温盐环流可能是主宰印度洋夏季风区、东亚夏季风区长期干湿变迁的主要因素。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

电导率是重要的地球物理参数。模拟地球内部条件下的矿物、岩石电导率测量是了解地球内部物质组成及物理化学性质的有效手段,同时,还可以为野外大地电磁测量结果的解释提供依据。在YJ-紧装式六面顶压机上,对原有的矿物、岩石电性测量系统进行了进一步的改进;建立了一套以Solartron 1260阻抗/增益一相位分析仪为测试仪器,使用Mo电极和Mo盾来控制样品氧逸度的测量系统,该系统的氧逸度环境为Mo-MoO2,接近Iw缓冲对。石英(人造水晶)、橄榄石、纯橄榄岩、辉石岩、二辉橄榄岩、巨晶辉石的电导率测量是在新的测量系统下获得的,而辉长岩的电导率测量是基于LCR仪为测量仪器的测试系统下获得的。在压力为1-3GPa、温度为675K-160OK、频率为106-0.1Hz、氧逸度为Mo-MoO2的条件下,对不同方向石英(人造水晶)的电学性质进行了研究。复阻抗平面上出现了反映样品本身性质的阻抗弧和反映样品与电极之间扩散的直线。石英的电导率随温度增加而增加,随压力的变化比较微弱。石英的导电机制主要为离子导电,载流子可能为碱金属离子和氢离子,这些碱金属离子和氢离子主要在平行于光轴的通道中运动。在相同的温度和压力条件下,a石英的电导率和c轴的夹角有关,石英的电导率随着夹角的增大而减小,表现出了强烈的各向异性。对“各个方向石英在发生了相变前后的电导率进行了研究,发现Q石英转变为p石英后,电导率并没有突变,仍然随着温度的增加而增加。在压力为1-2GP。、温度为563-1173K、频率为12-105Hz的条件下研究了辉长岩的阻抗。结果发现辉长岩复阻抗的实部随频率的增加而减小,而虚部随频率增加先增大后减小;相角随频率增加而减小。在复阻抗平面上出现了反映颗粒内部的阻抗弧,该阻抗弧出现在高频段。实验室获得辉长岩在地壳的压力和温度(1.0GP。和893K)条件下的电导率值为1.77×-4S/m,而高导层的电导率值为0-01-0-15S/m,二者相差了2-3个数量级,推断辉长岩不能在下地壳形成高导层。在压力为3.0GPa、温度为1299-1600K、频率为106-0.1Hz、氧逸度为Mo-MoO2条件下,对不同颗粒粒度的橄榄石电导率进行了测量。在复阻抗平面上均出现了反映颗粒内部电响应的阻抗弧,这些阻抗弧随着温度的增加而减小。而反映颗粒边界导电机制的阻抗弧并不明显,两种阻抗弧出现在不同的频率范围内,反映颗粒内部导电机制的阻抗弧出现在频率较高的范围内,而反映颗粒边界导电机制的阻抗弧出现在频率相对低的范围内。不同粒度橄榄石在3.0GPa条件下的电导率随着温度的增加而增加,它们的激化烩介于1.03-2.11ev之间。在压力为1-3GPa、温度为1282-1544K、频率为0.1-106Hz、氧逸度为MO-MoO2的条件下,对纯橄榄岩的电导率进行了测量。在复阻抗平面上出现了反映颗粒内部电响应和颗粒边界电响应的阻抗弧。反映颗粒内部导电的阻抗弧出现在较高的频率段,随着温度的增加,这些阻抗弧逐渐收缩。颗粒边界的阻抗弧出现在相对低的频率段。纯橄榄岩的电导率随着温度增加而增加,随压力变化比较微弱。对颗粒边界的电导率研究表明,颗粒边界的电导率高于颗粒内部的电导率,总电导率则小于颗粒内部和颗粒边界的电导率,颗粒边界并没有增强总电导率。纯橄榄岩的激化能为1,62eV,而激化体积为0.67cm3/mol,指前因子为5125加。利用实验所获得的拟合参数,建立了地球内部200-40Okm处的电导率模型,并同地球物理模型进行了对比,在温度和氧逸度的合理波动范围内,实验室电导率模型和地球物理模型吻合的很好。在压力为1-2GPa、温度为1228-1584K、频率为0.1-106Hz、氧逸度为MO-MoO2条件下,测量了天然和热压辉石岩、热压巨晶辉石、二辉橄榄岩的电导率。结果发现,在复阻抗平面上出现了反映颗粒内部电响应和颗粒边界电响应的阻抗弧,反映颗粒内部导电的阻抗弧出现在较高的频率段,随着温度的增加,这些阻抗弧逐渐收缩。颗粒边界的阻抗弧出现在相对低的频率段。辉石岩、二辉橄榄岩、巨晶辉石电导率随着温度增加而增加,随压力变化比较微弱。天然辉石岩和热压辉石岩颗粒边界的电导率高于它们各自颗粒内部的电导率,而总电导率则小于颗粒内部和颗粒边界的电导率,颗粒边界并没有增强总电导率。辉石岩一二辉橄榄岩一纯橄榄岩的电导率依次减小,这可能是与它们的铁含量有关。天然辉石岩的电导率与热压辉石岩的电导率的差异可能与样品中的水(氢)含量的不同有关。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

广西贺县龙水金矿位于湘桂稳定区,桂粤交界山脉的北段,博白-茶陵深断裂的西侧,区内广泛发育加里东期到燕山期的花岗岩,出露的基底地层主要为震旦系到寒武系。本文主要研究龙水金矿II号矿化带。该带位于寒武系水口群清溪亚群和大宁花岗闪长岩体的接触带附近,围岩为寒武系的碳质板岩,矿脉为硫化物石英脉,主要有黄铁矿、方铅矿、闪锌矿和石英等矿物。金矿化与硫化物密切相关。主要的金矿物为银金矿,少许自然金。确定金矿床的成矿年龄一直是个比较刺手的问题。本文选择矿脉中信为是成矿期的石英作为Rb-Sr等时年龄测定的对象,是基于其纯净和其中的原生气液包体基本可代表成矿热液的特征。结果表明其Rb-Sr等时年龄为120.5Ma,并认为此年龄代表了成矿年龄。有石英Rb-Sr等时线的~(87)Sr/~(86)Sr初始比为0.732089, 与矿脉中碳酸相加矿物的Sr同位素比值(约为0.7337-0.7402)一起,表明Sr应是来自地壳的富Rb盐矿物的Sr源区。另外,为了与围岩的蚀变年龄对比,测定了近矿围岩的Rb、Sr同位素组成,结果形成两条等时线,年龄分别为245.9 Ma和173.6 Ma,表明成矿以前至少发生了两次地质事件,导致了Sr同位素的均一化。这两次地质事件分别与华南的东吴运动及燕山运动第一幕相对应。矿石Pb同位素的~(206)Pb/~(204)Pb、 ~(207)Pb/~(204)Pb 和~(208)Pb/~(204)Pb 分别在18.4-18.9、15.6-16.1和38.4-39.6的范围内,并在~(207)Pb/~(204)Pb vs ~(206)Pb/~(204)Pb坐标图上呈现出斜率为1左右的线性排布。只有个别数据点要以得出依据Doe模式的模式年龄,约为200 Ma。在Zart,am Pb构造模式中,矿石Pb同位素数据大部分位于上地壳Pb线以上,呈现出富放射性成因Pb的特征。为了解释异常Pb的成因,本文进行了定量计算。结果表明矿石Pb为古老的存留地壳Pb与少地幔源Pb的混合,即矿石Pb同位素经历了这样的演化过程:在39-29.8亿年间由地幔分异出的地壳 Pb,未参与壳幔循环作用,一直到燕山期,与少量幔源Pb混合,并加入成矿。混合μ值为9.85-10.22。矿石的地质情况及矿石Pb同位素的Δα-Δβ-Δγ示踪结果均支持这一结论。本文初次研究了脉石英中的U、Pb同位素组成。脉石英中U含量很低。Pb同位素组成基本可以划分为两组,一组为与方铅矿数据近似的普通Pb组成,另一组则较富放射性成因Pb,并向围岩的Pb同位素组成漂移,可能是随着热液的演化和大气降水的加入,受围岩Pb的影响所致。矿脉中硫化物样品的S同位素比值(加权平均为0.16‰)和碳酸盐矿物样品的C同位素比值(在-0.1~-4.1‰的范围内),表明其应为内生来源。根据脉石英的气液包体均一温度(180-250 ),计算与脉石英存在0同位素平衡的热液的同位素的同位素组成,结果为1.2~-4.8‰,表明有大气降水的参与。石英气液包体水溶液为弱碱性,其成分分析表明其中K_2O/Na_2和CaO/MgO(分别根据K~+/Na~+和Ca~(2+)/Mg~(2+)的换算)与围岩相差很大。另外,矿石中微量元素主要为Au、A2g、Cu、Pb、Zn、Co、Ni、Mo、Bi、Ga、As、Sb、和Hg,而围岩中微量元素则主要为Cu、Ni、Mn、V、Zr、Ti、Cr和Ba。因此,热液中成矿元素主要不是来自围岩。黄铁矿的Co/Ni、S/Se/的比值可以指示热液化的来源。龙水金矿矿脉中黄铁矿的Co/Ni > 1,S/Se < 15000,均在与岩浆作用有关的热液范围内。因此,热液活动应主要与岩浆岩有关。矿石、围岩和花岗闪长岩的稀土配分模式相似,均呈现向右倾斜的V字型,并且类似于太古代后沉积岩。结合Pb、Sr同位素的研究,推测花岗闪长岩的源岩主要为古老的地壳物质。概括起来,龙水金矿床为约120.5 Ma形成的中低温热液矿床;热液中成矿物质主要来自花岗闪长岩。由于围岩与矿床紧密的空间联系及围岩中的高Au含量,围岩可能提供了一部分Au及其他成矿物质。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

本文首次采用长时间热模拟实验的方法,以未成熟的抚顺油页岩作为研究对象,模拟有机质在漫长的地质历史中的演化、成烃规律,重点研究了有机质早期低温成烃特征,探讨未成熟油形成机理,为油气生成理论提供新的信息。抚顺油页岩长时间热模拟实验的主要成果概括如下:1.抚顺油页岩长时间热模拟实验最重要的成晨是,证明了有机质在长时低温条件下能形成一定量的未成熟烃,并观察到干酷根低温成烃的即生即裂特征,从而使200 ℃低温释放了异常低温释放的类脂组分由于结合在干酷根的内部,受到干酷根大结构的保护,未曾受成熟作用的改造,较原样抽提物更能反映油页岩的生物母质来源。抚顺油页岩长时间低温成烃热模拟实验为未成熟油、低成熟油形成的研究提供了实验依据。2.抚顺油页岩干酷根为IIA型,形成于较开放的淡水湖泊相环境,生物来源丰富,以陆相高等植物的类脂组分输入为主,低等生物、微生物和细菌有很大的贡献。油页岩含有丰富的生物标志物,如倍半萜、三环萜、四环萜、4-甲基甾烷等,罕见的高4-甲基甾烷指数等标志物参数更进一步证明了油页岩抚顺生油母质的复杂性与多源性。3.不同温度段长时间热模拟实验证明了时间对温度的补偿作用,Ro、荧光参数、沥青A、族组成、生物标志物等参数都表明了本实验油页岩演化经历了四个阶段:250℃30天加热以前为未成熟阶段,250 ℃30天至300 ℃100小时为低成熟阶段,300 ℃100小时至350 ℃30天为成熟阶段,350 ℃30天以后为高成熟阶段,成熟度的划分不仅仅取决于温度,而是温度与时间的函数,时间对成熟度的影响在门限温度附近最大,时间越长,有机质成熟温度越低。

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Oxygen adsorption and desorption on a Pd(100) surface with a mesoscopic defect were studied by photoemission electron microscopy (PEEM). The defect surface, with an area of approximately 200 x 60 mu m(2), behaved differently from the perfect Pd(100) surface towards the adsorption of oxygen. When saturated, both surface oxygen and subsurface oxygen coexisted on the defect surface, whereas only surface oxygen was present on the Pd(100) surface. Upon heating, subsurface oxygen diffused back to the surface and desorbed with surface oxygen at the same time. The difference in oxygen adsorption ability between the defect surface and the perfect Pd(100) surface can be attributed to different structures of these two surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

An Approach to the Rehabilitation of Prelingually Deaf Children After Cochlear Implantation Zheng Xiujin(Medical Psychology) Directed by Professor Yin WenGang Abstract Objective: To sum up the acquirement rule of speech and language capability which is for the prelingually deaf children after cochlear implantation by listening and language rehabilitation training and to investigate the factors that affect rehabilitation speed. Method: Sixty-four children received a cochlear implant at the age of 2 to 5 years from 2001 to 2005. They begin to be trained under group pattern after switch on 1 month. The whole training program lasted more than 7 months; after that, according to the teacher’s plan the training program was to be continued at home. Result: The period is 108±7.7 days that they can pronounce correctly 50 percent of all of simple-finals and compound-finals, the period is 115.0±7.8 days that they begin auditory repeating, the period is 135.3±10.9 days that they can speech the first specific word independently and the period is 200.3±13.9 days that they can speak 70 words and come into tri-gamut-word and two-word sentence period. The patient that is the group at the age of 2-3 years can take part in normal kindergarten after switch on about 10 months. There are no significant differences in various grades of speech-language development with different age groups and so do with different sex groups. There are significant differences in various grade of speech-language development with various IQ group (P<0.01) and so do with using and not using hearing aids before implantation. Conclusion: From the research we find that the speech and language development sequence is the same level between the prelingually deaf children of 2 to 5 years who received cochlear implant after speech training and normal children and which are stages of uncomplicated sound production, continuous syllabic (babbling), speech sprout, single-word utterances and two-word utterances in proper order. The time is short significantly and the reason is that cognition capability is enhanced along with the increase of age. The intelligence is main factor that affect rehabilitation speed and the speed in the group of high IQ is faster than common IQ. It is not because of the dominance cognition of the senior group that makes the increasing of the rehabilitation, it even makes slowly. The reason of which is that the senior group are exposed the language environment too late to achieve speech and language development. So we should perform an operation and training early. The effectiveness of rehabilitation after cochlear implantation is improved by using hearing aids before implantation. The reason is auditory stimulate can be benefit of to deaf children. The rehabilitation speeds in the children at the age of 2 to 5 years have nothing to do with sex. Key words: cochlear implant; speech therapy; paediatric rehabilitation

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Processing of discrepant information is an important part in our everyday life. According to the social attributes of information, it can be categorized into two parts: social discrepancy and nonsocial discrepant information. The researches focused on nonsocial discrepancy are much mature than those of social discrepancy processing. This serial study employed three ERP experiments to explore the attributes of social discrepancy cognition. Experiment one compared the ERP differences between social and nonsocial discrepancy processing, experiment two adopted single stimulus paradigm to explore the negativity attention biases of social emotions, experiment three investigated the affective mechanism of emotions to social discrepancy information with cue-target paradigm, based on the experiment one and two. We invited healthy undergraduates to participate in our researches, in which social gender words and affective images were stimuli to explore the temporal sequences, activated modes and affective mechanisms of social discrepancy. The results were as below: 1. The differences of attention resource distributions between social and nonsocial information processing exhibited as early as 200 ms, since which P2 was evoked in both blocks. The larger P2 in nonsocial block represented the more attention to physical and nonsocial attributes of objects. N300/400 indicated the differences of evaluating systems in each block. The cognitive mechanisms of social and nonsocial tasks were specific, based on the fact: (1) the discrepancy evaluating system was activated earlier in nonsocial block than that of social block; (2) the social cognition performed right hemisphere advantage, but nonsocial task did not so. 2. Social emotions also could raise a negativity bias on attention. The latency of P2 evoked by social sad images was shorter than that of social happiness and neutral images. The latencies of P2 indicated that sad emotions attracted attention earlier, and possessed a processing advantage. The phenomenon that the larger N2 was evoked by social sadness showed that people was easily moved by sad emotions and sympathized the sadness. 3. Emotions affected social discrepancy processing. Positive affective mood magnified the discrepancy effect, based on the smaller latencies of difference N400 and larger amplitudes. Persons with happy mood synthesized social stereotypes to accelerate the social tasks. 4. Three experiments all showed the right hemisphere advantages of social cognition and social emotions, offered more proof in laterality hypothesis of social cognition. Above all, social cognition had essential distinctions with nonsocial cognition; they two had their own specific characteristics. The fact that social cognition was prone to be affected by different emotional mood made it more complex.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Risk perception is one of important subjects in management psychology and cognitive psychology. It is of great value in the theory and practice to investigate the social risk events that the public cares a lot especially in this social transition period. Furthermore, this study explored the factors that influence the risk perception and the results caused by risk perception. A survey including 30 hazards and 8 risk attributes was designed and distributed to about 3, 200 residents of 8 districts, Beijing. The major findings are listed as following: Firstly, combining the methods of system science and psychology, GAE program was used to indentify 7 groups of social risk events, such as national safe, government management, social stability, general mood of society, economic and finance, resources and environment & daily life problems. This study provided substance for the following studies and it was also a new attempt in research method which is of certain reference value for the related researches. Secondly, a scale of societal risk perception was designed and 2 factors were identified (Dread Risk & Unknown Risk). Reliability analysis, EFA and CFA show the reliability and validity of the societal risk questionnaire is good enough. The investigation using this scale showed that older participants and higher socioeconomic status perceived the societal hazards to be more threatening than did younger participants and lower socioeconomic status. However, there is no gender difference. Thirdly, structural equation model was used to analyze the influence factors and mechanism of societal risk perception. Risk taking, government support and social justice could influence societal risk perception directly. Government support moderated the relationship between government trust and societal risk perception. Societal risk perception influenced life satisfaction, public policy preferences and social development belief. Multi-group analysis was used to find out that the participants who have different socioeconomic status express different mechanism. Fourthly, the result of the research was used to explore the risk event of 2008 Olympic game. The results showed that government support and preparation of Olympic game influenced societal risk perception directly. Preparation moderated the relationship between government trust and risk perception. Risk perception influenced worry, effect of Olympic game and belief of successl. This result proved that risk perception could be used as an indicator. The indictor of risk perception was used to identify the characteristics of higher risk perception group. Finally, suggestions to the related decision were provide to the government.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Intergenerational cultural transmission is one process leading to cultural continuity and the transmission of value orientations may be seen as a core issue of cultural transmission. Previous research about value transmission revealed that the effectiveness of intergenerational value transmission was influenced by parenting, and parenting’s impact on culture transmission varies according to the cultural context. Value of children (VOC) refers to the functions children serve or the needs they fulfill for parents. VOC is contained in the value system and thus we would explore whether VOC could be transmitted from generation to generation like other values and how parenting impact intergenerational VOC transmission in China. Since there are dramatic differences between Chinese urban and rural context in many aspects, we would explore the effects of the transmission belt in these two social contexts respectively. A total of 200 samples were collected and each sample contained grandmother, mother and adolescent,and the results were as follows: 1. VOC could be transmitted from generation to generation, and the transmissions from grandmothers to adolescents were less effective than the transmissions from mothers to adolescents. 2. Parenting moderated the path of VOC transmission from mothers to adolescents. Authoritarian parenting could enhance the transmission of economical and social VOC factor between generations. And authoritative parenting could enhance the transmission of emotional VOC factor between generations. 3. Authoritarian parenting had significant positive predictive effect on rural adolescents’ VOC and had no predictive effect on urban adolescents’ VOC. And authoritative parenting had significant positive predictive effect on urban adolescents’ VOC.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A highly active catalyst, MnOx/TiO2-Al2O3, was prepared by impregnating MnOx species on TiO2-modified Al2O3. The TiO2 species in TiO2-Al2O3 support is in a monolayer dispersion, and the MnOx species is again highly dispersed on TiO2-Al2O3 Support. The total oxidation of chlorobenzene and o-dichlorobenzene on MnOx/TiO2-Al2O3 catalyst can be achieved at 300 degreesC and 250 degreesC respectively, at the space velocity of 8000 h(-1). The activity of MnOx/TiO2-Al2O3 catalyst (Mn loading 11.2 wt%) is gradually increased in the first 10-20 h and then keeps stable at least for the measured 52 h at 16,000 h(-1). Furthermore, no chlorinated organic byproducts are detected in the effluent during the oxidative destruction of chlorobenzene and o-dichlorobenzene. It is proposed that the partially chlorinated and highly dispersed manganese oxide on a monolayer TiO2-modified Al2O3 is responsible for the high and stable activity for the total oxidation of chlorinated aromatics. (C) 2001 Academic Press.