The boundary layer characteristics in the heavy fog formation process over Beijing and its adjacent areas   总被引：1，自引：0，他引：1  

ZHANG Guangzhi  BIAN Lingeng  WANG Jizhi  YANG Yuanqin  YAO Wenqing  XU Xiangde 《中国科学D辑(英文版)》2005,48(Z2)

By utilizing the Atmospheric Boundary Layer (ABL) observational data made available from the project "973" under the auspices of the Ministry of Science and Technology of the People's Republic of China - entitled the Beijing City Air Pollution Observation Field Experiment (BECAPEX), including the measurements by a wind profiler, captive airships, tower-based boundary layer wind and temperature gradient observational instruments (ultrasonic anemometers and electronic thermometers), air composition samplers, conventional upper-air, surface and Automatic Weather Stations (AWS) observations, this paper herewith analyzes, in a comprehensive manner, the occurrence of a heavy fog event over Beijing in February 2001, including its formation, development, persistence, dynamic and thermodynamic features as well as evolving stratification structures within the boundary layer at different stages. The results suggested: (i) as a typical case of urban heavy fog, before the fog onset over Beijing, a temperature inversion existed in the lower atmosphere, the smokes and the pollutants like SO2 and NO2 had been accumulated at a lower level. Proceeding the fog event, with the increase of SO2 and NO2 concentrations, condensability increased sharply. On the contrary, during the fog process, with increasing condensability, SO2 and NO2 concentrations decreased. This indicated that, acting as condensation nucleus, these accumulated pollutants were playing a key role in catalyzing the fog condensation. (ii) By analyzing mean gradient-, pulsation- and turbulence-distribution patterns derived from the wind measurements taken by the aforementioned tower-based instruments, they all indicated that about 10 hours before the fog onset, a signal foretelling potential strong disturbances in the lower boundary layer was detected, and a significant rise of both mean and disturbance kinetic energies was observed, revealing that the low-level wind shear was strengthened before the fog onset, consequently creating a favorable condition for the outbreak of turbulences. This strong signal seemed to be very meaningful in monitoring and predicting fog occurrence and its development. (iii) Once the fog was in shape, its condensation feedback effects tended to lift the height of temperature inversion layer within the mid and upper levels of the lower atmosphere, which in return determined the fog persistence and restructuring process.  相似文献   

长春市大气SO2时空分布与气象条件分析     

王德宣  刘洋 《地理科学》1995,15(3):289-294

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寒旱环境4种草本和灌木植物耐盐性试验研究   总被引：2，自引：0，他引：2       下载免费PDF全文

祁兆鑫  付江涛  刘亚斌  余冬梅  胡夏嵩  李淑霞  赵丹 《盐湖研究》2017,25(3):18-28

选取4种适宜于西宁盆地及其周边地区生长的老芒麦(Elymus sibiricus Linn.)、垂穗披碱草(Elymus nutans Griseb.)、柠条锦鸡儿(Caragana korshinskii Kom.)、霸王(Zygophyllum xanthoxylon Maxim.)作为供试种,采用室内种植方式进行0、30、60、90、120 mmol/L 5种浓度的Na_2SO_4溶液胁迫试验。研究4种植物地茎(径)、株高、干重等生长指标及地上和地下部分Na~+、K~+、Ca~(2+)、Mg~(2+)、Cl~-、SO_4~(2-)6种易溶盐离子含量,探讨4种植物的耐盐性特征。结果表明:盐胁迫对4种植物的生长具有一定抑制效应,其地茎(径)、株高、干重均逐渐降低,其中盐胁迫条件下对老芒麦的抑制作用相对较为显著,其次为垂穗披碱草、霸王和柠条锦鸡儿;随着胁迫浓度增加,4种植物地上和地下部分Na~+和SO_4~(2-)含量显著增加,而K~+、Ca~(2+)、Mg~(2+)、Cl~-含量呈逐渐降低;柠条锦鸡儿地上部分K~+/Na~+值相对较高,为0.73~9.70,其次为霸王和垂穗披碱草,为0.46~8.35和0.45~7.57,老芒麦相对较低,为0.25~6.12,表明区内4种植物耐盐性由大至小依次为柠条锦鸡儿、霸王、垂穗披碱草、老芒麦。研究结果对于西宁盆地及其周边地区开展利用植物有效防治土地盐渍化具有理论指导意义。  相似文献   

硫酸盐三氧同位素测试制样新技术——Ag2SO4热解法   总被引：1，自引：0，他引：1  

周爱国  刘存富  蔡鹤生  甘义群  李小倩  余婷婷  刘运德 《地球学报》2008,29(6):673-676

氧同位素能有效地示踪硫酸盐起源及其形成环境,随着硫酸盐中氧同位素质量不相关分馏现象的陆续发现,三氧同位素的研究已成为热点与前沿.笔者研究了硫酸盐三氧同位素(16O、17O、18O)测试制样的最新技术--Ag2SO4热解法.基本原理是:Ag2SO4在1050℃下热解为O2和SO2,其中O2产额可达(45±7)%,SO2产额接近100%,收集两种气体送作质谱分析可测得δ17O、δ18O和δ34S值.本方法的特殊要求是所有硫酸盐样品都必须转化为Ag2SO4,笔者详细介绍了水样、土样、石膏样品、BaSO4样品的处理方法与步骤.Ag2SO4热解法不再使用传统方法中的氟化试剂,安全可靠、价廉,顺应了环保意识和以人为本的原则.技术先进:适用性强,具有很大的推广应用价值.  相似文献   

云南高原楚雄市SO2浓度变化与热岛效应的关系研究     

何萍  董诗平  李宏波 《云南地理环境研究》2009,21(1):78-82

选取2001～2006年楚雄市及其郊区的气象资料,采用对比分析法对楚雄市的热岛效应情况进行了分析,得出楚雄市冬季热岛强度的日变化幅度较大,夏季热岛强度的13变化幅度较小,总的变化趋势是：夜间02时达到最大,以后温差逐渐减小,到下午14时达到最小,之后热岛强度又逐渐增强。在月际变化中楚雄市的热岛强度以2、3、4月份最强,以6、7、8月份最弱,这与中国北京、上海等部分大城市的热岛效应强度变化有显著差异。采用相关分析法对楚雄市SO2浓度变化与热岛效应强度变化之间的关系进行分析,得出楚雄市SO2浓度变化与热岛效应强度变化之间存在着线性正相关关系,其相关系数达0．626。  相似文献   

On So In Comets     

Krishna Swamy  K. S.  A'hearn  M. F. 《Earth, Moon, and Planets》1999,84(2):109-113

The solution of the statistical equilibrium equations for the SO molecule is used to estimate the expected intensities of microwave lines. The observed fluxes of the microwave lines of SO in Comet Hale–Bopp require approximately 1.8 10²⁸ mol/sec which give fluxes in the A³Π - X³Σ⁻bands below the observable limit, consistent with the observations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The Formation of Li-salts from Natural Brines During Isothermal Evaporation at 25 ℃          下载免费PDF全文

宋彭生  Dong Yaping  李武 《盐湖研究》2019,27(1)

Lithium and its compounds have very important applications in the new energy sources, new materials, and information technique industries. Lithium has two types of resources in nature: hard rock, e.g. Spodumene (LiAlSi2O6), Petalite(LiAlSi4O10), Lepidolite(K(Li,Al)3(Si,Al)4O10(F,OH)2), and brines, e.g. salt lake brines, oil well brines, underground brines etc. The biggest producer of Li commodities SQM in the world produces Li compounds from brines of famous salt lake Atacama on the central Andes Mountains in Chile  相似文献   

(NH_4)_2SO_4浸取EDTA-Zn测定试样中RE_2O_3     

童绍先  徐红梅 《云南地质》2012,(2):256-258,252

稀土元素的分析主要采用有机试剂萃取。偶氮试剂做为显色剂的比色分析,分析手续繁琐,也不易得到满意的分析结果,本文在EDTA容量法的基础上,采用较为简便的(NH4)2SO4浸取EDTA-Zn滴定法直接测定新型稀土总量,大大简化了试样的分析过程和操作手续。  相似文献   

In Situ Raman Spectroscopic Study of the Evaporation and Salt Precipitation:Indicates to Carbon Dioxide Injection into Brine in Reservoir for Sequestration     

CHEN Ying  GUO Huirong  LU Wanjun 《《地质学报》英文版》2013,87(Z1):936-937

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赤水河上游流域水化学变化与离子成因分析   总被引：5，自引：0，他引：5       下载免费PDF全文

耿金  陈建生  张时音 《水文》2013,33(1):44-50

选取赤水河上游流域的河水为研究对象,研究分析了河水的水化学特性沿流域空间变化以及主要离子特别是SO42-的来源等内容.结果显示:赤水河水质属低矿化度硬水,HCO3-和Ca2+为河水中的主要阴阳离子,赤水河是典型的碳酸盐岩河流.以白沙河为界,上段河流水化学组成变化平稳,离子主要来源于天然环境的输入,白沙河下游河流各化学组分差异显著,分析是受一定人为因素的影响.SO42-为次要阴离子,占阴离子总量的30％,发现SO42-与Ca2+、HCO3-与Mg+相关性较好,HCO3-与Ca2+相关性差,推断SO42-来源于石膏的溶解.但石膏的溶解还不能完全解释SO42-的来源问题,经分析环境酸化也是一种影响河水中SO42-含量的重要方式.  相似文献