四川盆地大雾成因剖析   总被引：7，自引：8，他引：7  

顾清源徐会明  陈朝平杨淑群 《气象科技》2006,34(2):162-165

为了构建“四川盆地大雾天气客观化预报系统”,采用天气学与统计学相结合的方法对四川盆地大雾天气的成因进行了剖析。分析表明,四川盆地多雾同四川盆地的地理环境所形成的近地层空气湿度大密切相关。形成四川盆地大雾天气的有利条件为:近地层层结稳定、近地层风力弱、近地层准饱和,大雾预报最为重要的是判断未来是否有降雨产生和辐射冷却强度。  相似文献   

云导风资料同化在伴随模式同化系统中的应用   总被引：5，自引：1，他引：5  

李红莉  沈桐立公颖 《气象科技》2006,34(4):358-363

以一次发生在长江流域的暴雨过程为例,设计了几种数值试验方案,并进行模拟。结果表明,MM5伴随模式同化系统能有效改善初始场与模式的协调能力,提高模式对于降水场和其它要素场的预报;使用云导风资料修正初始场后直接模拟的效果比未使用时直接模拟的效果要好,对部分区域的强降水预报精度有一定程度的改善;使用伴随模式同化系统后,加入云导风资料的同化试验对其它要素的改善与直接同化常规资料的效果相比,改善优势不明显,但从各要素的误差来看,对于风场的改善最好。  相似文献   

石家庄市污染日特征及其天气背景分析   总被引：8，自引：3，他引：8  

李国翠连志鸾  郭卫红陈静 《气象科技》2006,34(6):674-678

对石家庄市2002年1月到2004年12月空气质量达到中度及以上典型污染日进行了统计分析,得出典型污染日的分布特点、对应的气象要素特征及3种天气型。结果表明:典型污染日多出现在采暖季节,出现时间具有相对连续性;污染日分为沙尘和非沙尘两类,气象要素特征前者表现为风速大、湿度小、多正变压等锋后特征;后者则表现为地面风小、湿度高、多逆温层、大里查逊数等稳定大气层结,这些均为锋前特征;还侧重指出由于石家庄的特殊地形作用,高压前部型是石家庄重污染出现几率最多的天气类型。并由此提炼出中度以上污染日的预报要点,可供空气质量预报业务参考。  相似文献   

9711号台风与0509号台风能量场对比分析   总被引：2，自引：0，他引：2  

臧传花 《山东气象》2006,26(1):5-9

对比分析了9711号台风与0509号台风的环流背景和移动路径,并重点从能量角度分析了θse的时空分布特征,总结了造成两次台风过程降水分布差异的原因。结果表明,二个台风的路径相似,暴雨区分布在台风中心左侧2个经度至右侧4个经度范围内,右前侧暴雨强度更大,范围更广。与9711号台风相比,0509号台风暴雨的强度弱、范围小,对形成强降水不利的条件为:台风路径偏东;在台风北上过程中,西太平洋副高南撤使台风与副高之间的东南气流减弱;台风强度弱,能量衰减快,能量锋区在垂直方向发展不深厚。  相似文献   

青藏高原东北部强降水天气过程的气候特征分析   总被引：7，自引：2，他引：7  

谌芸  李强  李泽椿 《应用气象学报》2006,17(Z1):98-103

根据青藏高原东北部地区降水特点,定义青藏高原强降水概念,利用该区域内各测站自建站以来的气象资料,分析青藏高原强降水的时空分布特征和相对强度。结果表明:青藏高原东北部地区强降水的分布明显受到地形影响,年降水量和强降水次数自东向西呈阶梯性递减趋势,分别在青藏高原东北部的外流河谷地区和东南部四川北部地区存在大值中心;外流河谷地区两侧山脉的年降雨量较大,年均强降水日数较多,河源处相对较小,具有河谷地形的特点;青藏高原强降水的时段集中,雨强大,局地性强,且具有夜发性的特点;强降水日数和站数具有明显的年代际变化特征,近10年来出现区域性强降水的次数增加;青藏高原东北部外流河谷地区强降水的相对强度较大,同长江以南地区暴雨相对强度差不多。  相似文献   

太湖底泥中重金属污染及潜在生态危害评价   总被引：29，自引：0，他引：29  

向勇  缪启龙  丰江帆 《南京气象学院学报》2006,29(5):700-705

以太湖底泥为研究对象，分析太湖底泥中重金属的含量分布及富集状况，采用Lars HǎKanson潜在生态危害指数法对重金属的生态危害进行了评价。结果表明：各种重金属的含量分布呈现一定的区域特征，太湖湖岸区平均含量明显高于湖心区，从富集系数来看，Pb的富集程度最高，其次是Zn、Cu、As、Cr、Hg、Cd。太湖底泥重金属的潜在生态危害评价显示，除无锡片区犊山口Hg的污染属于中等生态危害外，其他各点重金属的生态危害都相对轻微，污染程度顺序为Hg〉Cd〉Pb〉As〉Cu〉Zn〉Cr．  相似文献   

A new schedule for copper chemical speciation analysis in soil and water sediment     

Hui ZHANG 《中国地球化学学报》2006,25(B08):197-197

The speciation of heavy metals is very important to evaluate their environmental impact. This issue has become an interested topic many decades ago and many significative studies were carried out such as direct detecting, calculation with mathematical model represented in recent years as well as Tessier＇s work in 1979, BCR＇s work in 1993, etc. In all of them, the methods recommended by Tessier and BCR are most often used in practical study today. But it should be seen that experimental schedule and agents define these methods including BCR＇s method, which improved on Tessier＇s method, only. In many cases, there always are deviations between analytical results and real content of the speciation. Otherwise, steps of the extraction experiment are always strict and excessive in the experimental process. The method, which is fitting to extract the speciation of bioavailability and easy to assess the effect of metals in the environment, is very anticipant. In this paper, the sequential three steps schedule of speciation analysis of copper in soil and water sediment is discussed as an example based on the comparative results of experimental analysis with the schedules of BCR＇s （mended by Rauret et al. in 1999） and TDPA （diethylenetriamine pentacetic acid） extraction, respectively. The results from sequential three steps method and other methods recommended by prevenient work suggest that the analytical schedule of sequential three steps of separating speciation （the speciation of easy effect to life-form, the speciation available to life-form, and the speciation of no effect to life-form） is valuable for copper speciation analysis in soil and sediment. Because of easy process and saving time to evaluate its availability for life form,  相似文献   

Comparison of components and distribution of heavy metals in sediments, suspended particulate matter and surface coatings in natural waters     

Deming DONG Yongzheng LU Xiuyi HUA Liang LIU Xiue SHEN 《中国地球化学学报》2006,25(B08):200-201

Solid phases, such as surface coatings （SC）, suspended particulate matter （SPM） and deposited sediments （DS）, contribute to the pool of heavy metals in natural waters. Their existing and forming conditions lead to potential differences in enrichment capacity of pollutants, chemical compositions and crystals. In this study, the contents of heavy metals in SC, SPM and DS were determined by GF-AAS after digestion with a mixture of concentrated HNO3 and HClO4. The selective extraction method was employed to remove Fe, Mn oxides and organic matters and associated heavy metals （Cu, Pb, Zn）. X-ray diffraction analyses were performed to characterize the crystals in the samples. The results showed that no significant difference in the contents of Fe-oxides in DS, SPM and SC was found, but the contents of Mn-oxides and organic matter follow the order of SC〉SPM〉DS. The significant crystal characters were observed in DS, SPM and SC, and the kinds of minerals and crystallization degree follow the order of DS〉SC〉SPM. In addition, quartz was the most important matter of crystals in the solid phases. Enrichment capacity follows the order of SPM〉SC〉DS for Pb, Cu and Zn. Organic matter was the major sorbent for Cu, and Mn oxides and organic matter played an important role in the enrichment of Zn. However, Pb was absorbed mainly by Fe oxides. Moreover, compared with Fe oxides and organic matter, Mn oxides had a great enrichment capacity for these metals. Although DS, SPM and SC were formed in the same water system, contents of chemical components, crystals and enrichment capacities to heavy metals were obviously different.  相似文献   

Influence of the environmental behavior and ecological effect of cropland heavy metal contaminants by CO2 enrichment in atmosphere     

Hongyan GUO Haixia JIA Jianguo ZHU Xiaorong WANG 《中国地球化学学报》2006,25(B08):212-212

Recently, the impacts of increasing atmospheric CO2 level on the terrestrial ecological system have been intensively studied. The higher the CO2 concentration, the higher the risk of destabilizing vulnerable carbon pool on ecological safety. Metabolism, biomass, activity, and diversity of microbial communities in soils can be significantly altered by the CO2 enrichment. For instance, it may accelerate carbonate weathering, vary the rhizospheric exudation, and enhance the amount of available C from the upper soil layer. However, how the CO2 enrichment would influence food safety such as species transformation and bioavailability of heavy metals in soils is remained unanswered. The bioavailability of heavy metals is strongly affected by bio-factors in addition to the physiochemical conditions of soils. Different physiological mechanisms and states control plant uptake of heavy metals. The enrichment of CO2 influences physiological functionalities of plants, and in turn, is expected to have impacts on the bioaccumulation of pollutants and the stress adjustment system of plants. Currently, in China soil is heavily polluted, in most cases, combined by organic pollutants and heavy metals. Studies of the environmental behavior and ecological effect of Cu in soil under elevated CO2 levels were conducted in China FACE （Free Air Carbon Dioxide Enrichment） from June to October 2005 using pot experiments. Results showed that the accumulation of Cu and Cd in leaves, stems, roots, and grains of rice growing in Cu contaminated soils was significantly lowered, indicating that the bioavailability of heavy metals in soils decreases with increasing CO2 concentration.  相似文献   

Heavy metal and arsenic distributions in soils surrounding Palapye, Botswana： An evaluation of environmental impact of coal mining and combustion in a sub-arid region     

Mingzhe ZHAI Otlogetswe Totolo Motsoptse P. Modisi Robert B. Finkelman Mingzhe ZHAI 《中国地球化学学报》2006,25(B08):53-54

Coal is an important natural resource in Botswana. The best coals so far found occur in the Morupule coalfield, west of Palapye, where nearly 8000 million tons have been identified （Carney et al., 1994）. In this study we investigate the environmental impact of the mining and consumption of the high-ash, medium-calorific value bituminous coal in the eastern part of Botswana, which may serve as a reference for other coal mines and coal-based power stations around the globe. More than two hundred surface soil samples and three profile soil samples were collected around Morupule Colliery, Morupule Power Station and Palapye.  相似文献