改进模拟退火法在估计河流水质参数中的应用

将模拟退火法应用于求解分析河流水团示踪试验数据，确定河流水质参数的函数优化问题。针对标准SA算法收敛速度缓慢的弱点，采取了增加附加约束条件、设置内阈值提前降温和增加记忆功能等综合措施对算法进行了改进。算例表明，综合改进措施能够明显地提高算法收敛速度，并可以得到满意的参数计算结果。计算结果也表明，内循环次数不会对外循环次数产生明显的影响。由于算法对目标函数没有附加要求，而且算法的收敛性与待估参数的初值无关，因此，改进SA算法在分析河流水质试验数据、确定水质参数方面．将会具有非常广的应用范围。     

内蒙古岱海表层沉积物中孢粉的分布及来源

岱海位于半干旱区东部边缘及东亚夏季风的尾闾区，生态环境体系脆弱，气候和环境变化敏感，是研究环境变化的理想地区。65个湖泊表层及入湖河流冲积物样品的孢粉分析揭示了岱海表层孢粉沉积特征及孢粉来源。岱海表层孢粉主要来源于区域性植被的孢粉，其总体特征反映了区域植被的组成，但不同部位孢粉组合的差异反映了湖滨当地植被的变化。受沉积环境的影响，岱海湖区孢粉浓度总体上要低于入湖河流孢粉浓度，湖区中部孢粉浓度最高。岱海孢粉以河流携带的为主，同时受风力传播的影响。蒿、藜科、桦、虎榛子等花粉和蕨类孢子以河流搬运的为主，松、禾本科及莎草科花粉可能还受风力传播的影响。一些仅在个别样品中出现且百分比很低的花粉类型如豆科、十字花科等还有可能是昆虫、鸟类或人类活动携带而来。     

北京山区野生观赏植物资源

对北京山区野生观赏植物资源进行了实地调查和统计分析，结果表明：有２２７种植物具有观赏意义，其中１０９种植物可重点引种或具有开展驯化试验研究价值。根据植物性质及其用途，初拟了野生观赏植物分类系统。并对北京山区的野生观赏植物按类别作了概要介绍和评价。最后对野生观赏植物的保护与合理开发利用提出了建议。     

RILL INITIATION AND EROSION ON HILLSLOPES IN THE HILLY LOESS REGION,WESTERN SHANXI PROVINCE

I. INTRODUCTIONSumming up recent research achievements, Huang (1993) pointed out that the capaciucs ordetachment and transport by rill now were much greater than tboso by rain drop impact and sheet now. soil erosion by water on upper slope area is frcquenhy discussed interms of interrill and rill erosional sub--processes. Compared with rill erosion, interrlll erosion contributes a very small proportion to the sediment transported downwards (Foster,1982). Field experiments conducted by Ca…     

天山乌鲁木齐河源冰川积雪化学特征及其季节变化

高海拔雪冰可以记录源自于地球表面的各种化学物质信号.从2002年9月到2005年10月3年的时段内,在天山乌鲁木齐河源1号冰川积累区采集积雪样品,运用比较法、相关分析法等方法,对其中主要离子、不溶粉尘、痕量金属和δ18O等特征及其季节变化进行了分析研究.分析结果表明,积雪离子浓度大小顺序依次为:Ca2+＞SO₄2-＞NO₃-＞Cl-＞NH₄+＞Mg2+＞Na+＞K+,其中Ca2+是主要的阳离子,SO₄2-是主要的阴离子.离子相关性分析表明,除NO₃-之外,其他离子浓度之间均存在较好的正相关.积雪中δ18O值随时间变化表现出与大气温度变化相反的规律.积雪中不溶粉尘和主要化学离子浓度具有明显的季节变化特征,春季期间浓度明显高于其他季节,表明沙尘活动对冰川区化学物质输入有较大贡献;此外,痕量金属(Cd、Pb、Zn、Al、Fe)季节变化特征表明,人类活动的污染物对于研究区雪冰中的化学特征亦有重要影响.      

稀土元素：海相硅岩沉积环境的有效指标

世界范围内海水的REE研究表明,不同环境海水的REE有一定的差异.海相硅质沉积也显示出与周围海水相似的REE特征,其中最明显的是Ce异常。对已知沉积环境的硅岩所作REE研究说明,利用硅岩的REE特征可以帮助判别海相沉积环境。江西南部寒武—奥陶系中广泛产出厚层的层状硅岩,根据Ce的异常,推测此区硅岩形成于大陆边缘—大洋盆地的过渡地区。     

河北滦河流域冲积物花粉与植被关系的研究

滦河流域13 个水文站不同时期(枯水期、洪水期、平水期)新鲜冲积物花粉分析表明，冲积物花粉组合受流域内植物花期影响。枯水期木本植物花粉含量高于草本植物，对应春季多数乔木花期。平水期草本植物花粉含量高于木本植物，对应夏、秋季多数草本植物花期。洪水期草本植物花粉含量略高于木本植物。洪水期冲积物中的木本植物花粉主要是由雨水片流将春季落入表土的花粉带入河水中所致。燕山地区的冲积物主要系洪水期沉积，所以燕山地区冲积物花粉组合中20%～40%的乔木花粉代表了现在燕山山区20%～25%的森林覆盖率，这为根据冲积物花粉定量恢复古植被森林覆盖率提供了现代依据。     

白云鄂博地区碳酸岩墙及岩墙旁侧石英岩中的包裹体研究

白云鄂博的碳酸岩墙中包裹体类型有多子晶包裹体、两相水溶液包裹体、含CO_2三相包裹体和含子晶三相包裹体,岩相学和显微测温结果表明,这些包裹体与国外典型的碳酸岩中的包裹体具有很大程度的一致性,反映了其岩浆成因特点;碳酸岩墙中旁侧的白云鄂博H2石英岩中含有大量的流体包裹体,主要类型为NaCl-H_2O包裹体、CO_2包裹体和H_2O±CO_2±固体的包裹体。包裹体的岩相学、显微测温、阴极发光特征、包裹体成分ICP-MS测定,激光拉曼研究等,揭示出石英岩中的包裹体捕获了来自碳酸岩墙的碳酸岩浆流体,提供了一种不可多得的直接研究碳酸岩流体的手段。     

Climate Change and Pastoral Economy in Kenya:A Blinking Future

Abstract: The present paper examines the changing climatic scenarios and associated effects on livestock farming (pastoralism) in the arid and semi arid lands (ASAL) of Kenya, which cover over 80% of the country. The study was carried out in the semi arid Mukogodo Division of Laikipia District in Kenya. This division received a mean annual rainfall of approximately 507.8?mm and the main source of livelihood was pastoralism. Questionnaire, structured interview, observation and literature review were the main methods of data collection. Rainfall was used in delineating changes in climate. Standardized precipitation index (SPI) and Markov process were used in analyzing drought severity and persistence, respectively. Approximately 38% of all droughts between 1975 and 2005 were prolonged and extremely severe, with cumulative severity indices ranging between ?2.54 and ?6.49. The probability that normal climatic conditions persisted for two or more consecutive years in Mukogodo Division remained constant at approximately 52%. However, the probability of wet years persisting for two or more years showed a declining trend, while persistence of dry years increased with duration. A drying climatic trend was established. This drying trend in the area led to increased land degradation and encroachment of invasive nonpalatable bushes. The net effect on pastoralism was large-scale livestock loss through starvation, disease and cattle rustling. Proper drought monitoring and accurate forecasts, community participation in all government interventions, infrastructural development in the ASAL and allocation of adequate resources for livestock development are some of the measures necessary for mitigating the dwindling pastoral economy in Kenya and other parts of the world.     

Global Change and Regional Landscape Response and Desertification in Siberia

Climate changes and associated natural and anthropogenic processes have manifested themselves particularly clearly during the last two decades. The study of consequences of these changes has become one of the central scientific, social and political issues of our time (Pilot 2000; UNEP 2007).