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   

南岭山地高速公路路面温度变化特征分析   总被引：5，自引：1，他引：5  

吴晟 吴兑邓雪娇  谭浩波 《气象科技》2006,34(6):783-787

使用2003年3月至2005年8月南岭山地京珠高速公路粤境北段云岩路段3套自动气象站的逐分钟路面温度、地温、气温、湿度、风向、风速等气象资料,分析研究了南岭山地高速公路的路面温度特征及其与天气状况、气温、风速等气象条件的关系,并讨论了地形对南岭山地高速公路路面温度的影响。研究结果表明,南岭山地高速公路晴天和多云时的路面温度日变化明显,与辐射过程密切相关。路温与气温、地温的差异在晴天午后最为明显。晴天时路温、地温、气温的年变化趋势比较一致,路温与地温之间保持着明显的温差;多云天气时路温与地温的差值明显缩小,阴天时路温与地温的差值非常小。地形对路面温度有明显影响,高海拔地区路面温度相对较低,南岭北坡路面温度明显高于南坡,与局地小地形有关。高温过程时路面温度最高接近60℃,地温也超过50℃,持续高温对行车安全、路面和路基结构均有很大威胁。  相似文献   

以风场和湿度的显著季节变化确定全球季风的分布     

郑彬 《气象科学》2006,26(5):473-477

利用1958~2003年对流层相对湿度和风场(NCEP/NCAR再分析资料)的季节变化来定义盛行风的季节变化引起的天气气候明显变化的区域———季风区。通过分析表明,对流层低层的风场季节变率可以描述传统的季风区,但是在传统季风区以外,也有风场季节变率大的区域。利用中高层相对湿度的显著季节变化(热带地区季节变化大于20%,副热带地区大于10%,赤道地区以风向的季节变化大于90°)可以弥补风场季节变率的不足。由它们二者确定的季风区物理意义明确,有较大的合理性。  相似文献   

和田市能见度变化趋势及其与空气质量的关系     

玉苏甫·阿布都拉  热依汗古丽  买买提阿布都拉  米吉提·依明  Yusup·ABDULLA  Reyhanguli  Maimaitiabudula  Mijit·IMIN 《沙漠与绿洲气象(新疆气象)》2006,29(1):24-25,29

对1963～2004年和田市各级别大气能见度进行统计分析,揭示了大气能见度的年际变化和季节变化特征。近20a来和田市大气环境质量趋于好转,造成能见度恶化的重要原因是大气中悬浮颗粒的增多,因此大气能见度是评价大气环境质量的重要指标。  相似文献   

Impact of forest fires on regional air quality in Southeast Asia     

Rajasekhar Balasubramanian Siao Wee See 《中国地球化学学报》2006,25(B08):221-222

Biomass burning, the burning of living and dead vegetation for land-clearing and land-use change, has been in practice in many tropical countries such as Brazil, Indonesia, Nigeria, and Mexico. Intense forest fires can also ignite subsurface organic soil components （e.g. peat）, which can continue to smolder long after the original surface fires are put out. Combustion of vegetation and peat has only recently been recognized as a major source of atmospheric pollution. The immediate effect of burning is the production and release of gases and particles into the atmosphere, in quantities that in some cases can be significant not only locally and regionally but also on a global scale. Vegetation fire emissions account for roughly half of the atmospheric constituents of hydrocarbon, carbon monoxide, nitrogen oxides, and precursors of tropospheric ozone and may be the second largest source of anthropogenic aerosols after the production of sulfates from SO2. As a result, there has been considerable interest in studying the contribution of forest fires to the production of air pollutants. In recent years, Southeast Asian countries have been affected repeatedly by episodes of smoke haze from forest fires in Indonesia. During 1997-1998, the region was again shrouded in a haze worsened by prolonged drought linked to the E1 Nino weather phenomenon. Satellite pictures confirmed that air pollutants, originating from fires covering an estimated 800000 hectares of southern Kalimantan, Sumatra, and Java, have been transported by southwesterly monsoon winds across neighbouring Malaysia and Singapore to as far as Thailand and the Philippines. The impact of these extensive fires on the health of the residents and ecology in the affected areas was substantial, costly, and possibly long lasting. Most of the research on the environmental aspects of biomass burning has been directed towards the tropics in Africa and America, specifically to the tropical rain forests of Brazil and to the savannas of Africa and South America.  相似文献   

Emplaced Geotechnical Characteristics of Hydraulic Fills in a Number of Australian Mines     

K. J. Rankine  N. Sivakugan  R. Cowling 《Geotechnical and Geological Engineering》2006,24(1):1-14

Hydraulic fills used in Australian mines have similar grain size distributions whilst having quite different specific gravity values, typically in the range of 2.7–4.4. When produced and distributed in slurry at 65–75% by solid content, they settle to produce fills with similar geotechnical characteristics. The fills under investigation have been found to settle, in the laboratory, to a dry density of about 0.56 × specific gravity, a saturation water content of about 17–34%, and a porosity of 37–49%. A quick estimate of the optimum water content that gives the minimum porosity may be obtained by locating the intersection of the saturation curve and minimum porosity line, which may simply be done on a water content vs. porosity plot. However, transportability of the slurry requires it to be mixed at water content substantially greater than the optimum water content. As the tailings settle out of suspension, they settle to relative density of 50–80%. This paper shows that the current empirical relationships relating relative density and N-value to friction angle for sands will significantly underestimate the friction angle of the hydraulic fills. Based on limited experimental data, a unique relationship between relative density and friction angle is proposed for hydraulic fills placed in some Australian mines.  相似文献   

Trace elements in natural organic-rich surface soils： Contributions from natural and anthropogenic sources     

Eiliv Steinnes 《中国地球化学学报》2006,25(B08):5-5

A large part of the Northem Hemisphere is covered by podzols and similar soil types, which have a surface layer characterized by high organic matter content. This layer is extremely important because it is the main source of plant nutrients. The elemental composition of the surface soil however is often strongly different from that of the underlying mineral soil, which may be due to a combination of natural processes and anthropogenic influence. Research in Norway over the last 30 years has contr/buted to the understanding of the relative importance of different factors in modifying the chemistry of the surface soil. The country is relatively pristine, but is substantially influenced in the south by atmospheric supply of pollutants from other parts of Europe. Vegetation is relatively uniform over large parts of the country, but climatic variations related to oceanic influence are considerable.  相似文献   

Fine-particle Mn and other metals linked to the introduction of MMT into gasoline in Sydney, Australia： Results of a natural experiment     

Brian Gulson David Cohen J. Michael Davis Ed Stelcer D. Garton Olg Hawas Alan Taylor 《中国地球化学学报》2006,25(B08):62-63

PM2.5 particulates were analyzed using accelerator-based ion beam methods for a suite of 21 species （H, C, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Pb） to evaluate the contribution to Sydney air associated with the introduction of MMT as a replacement for Pb. MMT was discontinued in 2004. Teflon filters continuously sampled for 7 years from 1998 to 2004 were analyzed from two sites： a suburb （Mascot） close to the Central Business District [CBD （n=718）] and a high trafficked area, and a relatively rural （background） setting, ～20 km west of the CBD （n=730）. Mean Mn concentrations in air at the background site increased from 1.5- 1.6 ng/m^3 to 〈2 ng/m^3 at the time of the greatest MMT use whereas those at Mascot increased from about 2 to 5 ng/m^3. From the maximum values, the Mn showed a steady decrease at both sites concomitant with the decreasing use of MMT. Lead concentrations in air at both sites decreased from 1998 onwards, concomitant with the phase out of leaded gasoline in 2002. A high correlation was obtained for the relationship between Mn in air and lead replacement gasoline （LRG） use （R2 0.83） and an improved correlation for Mn/Al＋Si＋K and LRG use （R2 0.93）. With Mn concentrations normalized to background values of Al＋Si＋K to account for the lithogenically-derived Mn, the proportion of anthropogenic Mn was -70%. Changes for Mn and Pb in the particulates are attributed to the before-during-after use of MMT and decreasing use of Pb in gasoline.  相似文献   

Calibration of Four Species of Tillandsia as Air Pollution Biomonitors   总被引：1，自引：0，他引：1  

Eduardo D. Wannaz  María L. Pignata 《Journal of Atmospheric Chemistry》2006,53(3):185-209

Many organisms have been used as bioindicators of atmospheric contamination, with moss and lichen species being the most common. However, studies using epiphytic vascular species of Tillandsia have shown a good correlation between the presence of pollutants and the bioindicator's response. Therefore, the aim of our investigation was to calibrate and compare the response of four Tillandsia species of Argentina to ascertain whether they could be used as atmospheric contamination biomonitors. For this, we analysed the correlation between the levels of heavy metals in total atmospheric deposition samples and: a) their rate of enrichment; b) the physiological response of the plant samples. Tillandsia samples collected from a non contaminated area in the province of Córdoba were transplanted to four areas in the capital city with different sources of pollution (industrial or traffic emissions). They were exposed for a period of 3 to 6 months after which the concentrations of Pb, Ni, Fe, Zn, Cu and S as well as the physiological parameters of foliar damage were determined. Simultaneously samples of total atmospheric deposition were also taken.The highest level of metal enrichment was found in T. capillaris followed by T. tricholepis, T. permutata and T. retorta. Also, the use of a foliar damage index proved to be effective and could be a useful tool to evaluate different levels of atmospheric quality in these species. The rate of heavy metal deposition was higher in the industrial area for all metals except for Zn whose values were higher in areas with high levels of traffic.  相似文献   

Seasonal changes in ground‐penetrating radar signature observed at a polythermal glacier,Bylot Island,Canada     

T. D. L. Irvine‐Fynn  B. J. Moorman  J. L. M. Williams  F. S. A. Walter 《地球表面变化过程与地形》2006,31(7):892-909

In recent years, ground‐penetrating radar (GPR) has been increasingly used for characterization of subglacial and englacial environments at polythermal glaciers. The geophysical method is able to exploit the dielectric difference between water, air, sediment and ice, allowing delineation of subsurface hydrological, thermal and structural conditions. More recent GPR research has endeavoured to examine temporal change in glaciers, in particular the distribution of the cold ice zone at polythermal glaciers. However, the exact nature of temporal change that can be identified using GPR has not been fully examined. This research presents the results of three GPR surveys conducted over the course of a summer ablation season at a polythermal glacier in the Canadian Arctic. A total of approximately 30 km of GPR profiles were collected in 2002 repeatedly covering the lower 2 km of Stagnation Glacier, Bylot Island (72°58′ N 78°22′ W). Comparison between profiles indicated changes in the radar signature, including increased noise, appearance and disappearance of englacial reflections, and signal attenuation in the latter survey. Further, an area of chaotic returns in up‐glacier locations, which was interpreted to be a wet temperate ice zone, showed marked recession over the course of the ablation season. Combining all the temporal changes that were detected by GPR, results indicate that a polythermal glacier may exhibit strongly seasonal changes in hydrological and thermal characteristics throughout the ice body, including the drainage of 17 000 m³ of temporarily stored intra‐glacial meltwater. It is also proposed that the liquid water content in the temperate ice zone of polythermal glaciers can be described as a fraction of a specific retention capacity. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献