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单体同位素分析在有机污染物研究中的应用进展 总被引：5，自引：0，他引：5
单体同位素分析(Compound-Specific Isotope Analysis, CSIA)是1990年代发展成熟的现代分析方法,日渐应用于环境分析领域,成为当前研究有机污染物最具有应用前景的技术之一.当前CSIA技术在有机污染物研究中的应用主要集中在污染物来源判识、生物转化及降解机理研究等方面,本文主要综述了CSIA在有机污染物生物转化的证明和转化机理研究方面的进展. 相似文献
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综合考虑了数值天气预报过程中的两种不确定性：初值和模式的不确定性，建立了一个拥有20个成员的中尺度集合预报系统来模拟1997年热带气旋Danny的路径和对流系统.发现模拟气旋路径的集合平均误差在12 h以后比所有成员的误差都小.通过考察模拟结果对各种不确定性的敏感性，发现两种不确定性在模拟中都很重要,但不同的不确定性对模拟结果的贡献是不同的.初值的不确定性主要影响模式积分的前12 h，模式的不确定性在整个积分过程中始终存在.不确定性最敏感的区域主要分布在气旋附近的强天气区. 相似文献
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1地勘企业职工人股历史回顾
地勘企业职工入股,搞股份制改革,较早可以追溯到1997年（有些单位可能更早）。国家体改委曾在总结山东诸城等地国有中小企业改制经验的基础上,发布了《关于发展城市股份合作制企业的指导意见》。一些地勘单位受地方企业成功经验的启示和鼓舞,再加上地勘单位自身深化改革、参与市场竞争的需要,选择了少数下属企业进行股份合作制的改革。基本做法是,对企业进行资产剥离、清产核资和资产评估后,将净资产卖给企业职工,实现劳动者和资本所有者的联合, 相似文献
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吉南张三沟岩组和金银别岩组发育一套高镁安山岩类,SHRIMP锆石U-Pb定年为（2 493±12）Ma,形成于新太古代。高镁安山岩类属于钙碱性系列,w(SiO2)为 53.93%～57.90%,富MgO(w(MgO)为6.54%～8.82%）,高Mg#值(0.68～0.71, 平均0.69),高铬(w(Cr)为(270.66～1 117.30)×10－6,平均443.62×10－6）,高镍(w(Ni) 为(141.74～542.98)×10－6,平均250.50×10－6）,这种高MgO、Cr、Ni的特征表明其成因与地幔部分熔融有关。另一方面,该岩石富集大离子亲石元素（如Sr、Cs、K、Pb、Rb和Ba）,亏损高场强元素（如Nb、Ta、Ti、P）,富集LREE（w(Ce)为(38.34～59.34)×10－6）,亏损HREE（w(Yb)为(1.38～1.57)×10－6）,显示弧火山岩的特点。上述地球化学特征表明,岩石可能是消减板片脱水流体或者消减板片部分熔融的熔体与地幔橄榄岩相互作用的结果,揭示它们形成于消减带的构造环境,表明新太古代已经存在现代类型的板块构造。 相似文献
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Snow cover on the Tibetan Plateau (TP) has been shown to be essential for the East Asian summer monsoon. In this paper, we demonstrate that tropical cyclone (TC) 04B (1999) in the northern Indian Ocean, which made landfall during the autumn of 1999, may have contributed to climate anomalies over East Asia during the following spring and summer by increasing snow cover on the TP. Observations indicate that snow cover on the TP increased markedly after TC 04B (1999) made landfall in October of 1999. Sensitivity experiments, in which the TC was removed from a numerical model simulation of the initial field, verified that TC 04B (1999) affected the distribution as well as increased the amount of snow on the TP. In addition, the short-term numerical modeling of the climate over the region showed that the positive snow cover anomaly induced negative surface temperature, negative sensible heat flux, positive latent heat flux, and positive soil temperature anomalies over the central and southern TP during the following spring and summer. These climate anomalies over the TP were associated with positive (negative) summer precipitation anomalies over the Yangtze River valley (along the southeastern coast of China). 相似文献
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There was a new concept of ‘adaptive or targeting observation’ in recent years, which is an
additional and targeting observation based on the existing and fixed observing network for the atmosphere on the
impacted region. Dropsonde is one of the important observing instruments in the adaptive or targeting
observation. In this paper, GRAPES, the next generation of numerical weather prediction system of China has
been used. The impacts on the typhoon Dujuan (No.200315) forecast in experiments with dropsonde have been
studied and experiments on sensitivity have also been done. It was found that the forecasts of the elements have
been improved obviously with the use of dropsonde, such as the path, the center location, and the intensity of
typhoon. It was also found in the sensitivity studies that the setting of deviation structure also has obvious
impacts on the forecast for typhoons. It is not true that the simulation is better when the proportion of the data of dropsonde is larger in the course to modify the background. 相似文献
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选择蒽、9-甲基蒽和9,10-二甲基蒽作为模型化合物,以李村河口区沉积物为培养基质,进行实验室好氧微生态培养,通过超声萃取-柱层析-气相色谱法测定目标污染物浓度随培养时间的变化,研究了它们在自然菌群作用下的生物降解行为。测定方法的基质加标回收率在66.20%~82.95%之间,相对标准偏差在3.34%~6.19%之间。6个月的好氧生物降解实验表明,沉积物中本底蒽由32.88 ng.g-1降到32.32 ng.g-1,降解率仅为1.70%;而在添加了蒽的沉积物样品中其浓度由170.40 ng.g-1降到151.36 ng.g-1,降解率高达11.17%;加入的9-甲基蒽和9,10-二甲基蒽的浓度也分别由133.84 ng.g-1和144.26 ng.g-1减少至122.52 ng.g-1和135.13 ng.g-1,降解率分别达到8.46%和6.33%。相同条件下三种有机污染物的不同降解速率表明,9,10位取代使得蒽在沉积环境中更加持久,自然降解速率更慢 相似文献