亚洲沙尘两大源区之一——中国戈壁沙漠的气溶胶表征与识别

源于中国戈壁沙漠的亚洲沙尘可以通过长途传输到我国下游城市地区并进入太平洋,对城市空气质量、海洋初级生产力及全球气候产生重要影响.于2006~2008年春季对位于中国戈壁沙漠东北部多伦地区气溶胶的理化特性进行了研究,并与其他亚洲沙尘源区的气溶胶作比较.发现2006~2008年多伦地区TSP的平均浓度分别为446.4,183.7,176.1μg/m3,PM2.5的平均浓度分别为125.6,86.7,77.9μg/m3.气溶胶中Cu、P的质量百分数均显著高于地壳中的质量百分数,可能受到内蒙古富含铜矿和磷矿的影响.以多伦为代表的戈壁沙尘气溶胶[Ca〗/[Al]平均比值为0.5左右,低于源于中国西部(新疆地区)的沙尘(1.5);沙尘暴期间的[Na+]/[Na],[Mg2+]/[Mg],和[SO42-〗/3/[S]也低于其他沙尘源区的比值,表明中国戈壁沙漠相比于其他源区将向下游地区输送较多不可溶的钠、镁、硫,对空气质量和气候变化产生不同影响.     

东亚典型站点混合型气溶胶光学特性和辐射效应对比

根据东亚地区沙尘传输路径上人为污染程度的不同,选取AERONET典型站点SACOL、Beijing和Gwangju_GIST站的观测数据,结合SBDART辐射传输模式,对比分析了东亚地区混合型气溶胶的光学特性、辐射效应以及不同程度大气污染对气溶胶混合的影响.结果表明,与沙尘气溶胶和人为气溶胶相比,东亚混合型气溶胶吸收能力最强,特别在可见光波段,导致地表冷却和大气加热效应加强,大气层顶冷却效应减弱. Beijing站比SACOL、Gwangju_GIST站混合型气溶胶浓度更高,吸收能力更强,地表冷却和大气加热效率更强,大气层顶冷却效率更弱.粗模态沙尘气溶胶与细模态人为气溶胶对于混合型气溶胶的生成和辐射吸收能力的增强都有着极为重要的作用.混合型气溶胶在东亚区域重污染(雾霾)过程中有重要作用.     

一次典型沙尘天气过程对甘肃空气质量的影响

利用气象信息综合分析处理系统气象数据、ERA-Interim再分析资料,结合后向轨迹模式(HYSPLIT)、中分辨率成像光谱仪卫星数据和逐小时空气质量数据,分析了一次典型的甘肃沙尘天气过程的成因及其影响.结果表明,此次沙尘天气是由高空槽东移发展,冷空气南下,配合地面高压系统和锋面东移,冷锋后强气压梯度形成大风造成的; HYSPLIT模式模拟结果与气溶胶光学厚度分布显示沙尘天气沿西北路径传输,沙尘源地位于南疆地区,沿河西走廊向东南传输至陇中地区;沙尘天气发生前沙尘源地气温上升造成土壤湿度下降,低层大气处于不稳定状态,有利于起沙,沙尘期间各层水平风速均较大,有利于沙尘的水平输送;沙尘源地和武威沙尘加强区中低层的垂直方向皆为上升运动,有利于将沙尘源地的沙尘粒子带入高空,传输路径中的酒泉、张掖和兰州为下沉运动,有利于将沙尘带至近地面,形成沙尘天气.沙尘天气影响了甘肃绝大部分地区的空气质量,影响由西北向东南减弱, 7个城市空气质量指数≥500的持续时间超过10 h,张掖达19 h,酒泉、武威和兰州达16h;沙尘天气对甘肃各城市污染物质量浓度的影响由西北向东南减弱,对甘肃中西部城市颗粒物质量浓度影响最大:武威w(PM_(10))最大值达8 771μg/m~3,是沙尘天气发生前的258倍, w(PM_(2.5))最大值为1516μg/m~3,是沙尘天气发生前的95倍,沙尘天气期间风速增大,省内中西部城市气态污染物质量浓度下降,兰州w(SO_2)由沙尘天气前30μg/m~3以上,最高80μg/m~3降至沙尘天气时的20μg/m~3以下, w(NO_2)由65μg/m~3以上,最高123μg/m~3,降至沙尘天气时的30μg/m~3以下,沙尘天气结束后气态污染物质量浓度缓慢上升.     

东亚高空大气气溶胶的分布及沙尘输送特征研究

利用长达20 年的SAGEⅡ(stratospheric aerosol and gas experimentⅡ) 资料, 研究了东亚地区5.0 ～15.0 km 高空气溶胶多年时空分布特征和变化趋势, 并研究了东亚沙尘活动对高空及下游的气溶胶输送。发现东亚高空气溶胶水平分布呈现上中下3 层不同的分布特征, 下层 5. 0 ～8. 5 km 高值区对应气溶胶源区青藏高原和西北沙漠地区;中层 9. 0 ～10. 0 km 高值区对应温带气旋高发的中纬度地区;上层 10. 5 ～15. 0 km 表现为低纬气溶胶含量显著高于高纬地区。高空各层气溶胶的空间分布受天气系统的影响具有明显的季节变化。近10 年来东亚高空气溶胶呈减少趋势, 平均光学厚度约下降了0. 016。另外还发现沙尘活动与 5. 0 ～11. 5 km 范围内的气溶胶显著相关, 反映沙尘活动影响的高度范围可以达到整个对流层。定义沙尘暴高空影响指数, 用来分析东亚沙尘暴对下游地区的影响, 发现随着时间推移沙尘逐渐向东移动, 在约 12 天之后可以到达大西洋。     

兰州远郊区春季碳气溶胶的质量浓度特征

 为探讨春季沙尘(暴)期间兰州大学半干旱气候与环境观测站(SACOL)碳气溶胶的变化特征, 2012 年5 月17-26 日于SACOL 站采用石英膜收集PM₁₀样品, 利用DRI-2001A 热/光碳分析仪测量元素碳(EC)和有机碳(OC)的质量浓度。结果显示, 沙尘(暴)是导致OC、EC 质量浓度增大的主要因素。采样期间EC、OC 和总碳(TC)的平均质量浓度分别为2.71、11.26 和13.97 μg/m³。进一步分析显示, 沙尘(暴)期间兰州城区碳气溶胶污染逐渐加重主要受本地源的影响。PM₁₀中OC 和EC 的相关系数达到0.94, 揭示SACOL 站OC、EC 的来源相对一致。OC/EC 的均值为5.05, 表明春季SACOL 站PM₁₀中碳气溶胶存在二次污染。二次有机碳(SOC)的质量浓度为3.37 μg/m³, 为OC 的29.9%。结合考察周边环境, 分析表明SACOL 站春季碳气溶胶的主要来源是直接污染源, 来自周边环境中的燃煤以及机动车尾气排放。对碳气溶胶8 种组分的因子分析结果也表明, 周边环境的燃煤和机动车尾气排放是春季SACOL 站碳气溶胶的主要贡献源。     

北京沙尘天气污染分析

本文阐述了北京沙尘天气的总体概况.春季沙尘多发季节,颗粒物浓度明显高于其它季节,且以粗颗粒为主.沙尘对太阳辐射的消光作用明显低于城市型二次粒子,沙尘天气期间气溶胶光学厚度往往低于前期局地积累造成的城市型污染阶段.北京的沙尘天气与气象条件密切相关,特别受高低压配合影响,由低压底部伸出的冷锋是重要的起沙条件.沙尘天气过程中,大颗粒物浓度明显上升,但大风的到来带走了城市型污染物,特别是气态污染物,如SO2浓度急剧下降,细颗粒物浓度也有降低趋势.     

SACOL黑碳和沙尘气溶胶辐射强迫分析

利用兰州大学半干旱气候与环境观测站(SACOL)的太阳光度计资料、AREONET气溶胶光学特性资料,采用辐射传输模式SBDART分析了SACOL典型日个例沙尘气溶胶和黑碳气溶胶的长、短波辐射强迫,探讨了不同地表反照率和天顶角对气溶胶辐射强迫的影响.分析表明,沙尘和黑碳在地表的短波辐射强迫分别是-146.54,-60 W/m~2,长波辐射强迫分别是17.79,8.66 W/m~2,短波辐射强迫是长波的6倍多,沙尘辐射强迫是黑碳的2倍多;在大气层顶沙尘和黑碳短波辐射强迫是39.04,27.2 W/m~2,长波辐射强迫为12.19,5.0 W/m~2.短波辐射强迫随地表反照率的增加而增大,长波辐射强迫随地表反照率的增加线性减小.随天顶角减小,大气层顶的短波辐射强迫线性增加,地面短波辐射强迫对数减小,长波辐射强迫随天顶角的变化很小.     

格尔木地区沙尘气溶胶铁氧化物漫反射光谱分析

格尔木地区沙尘气溶胶漫反射光谱分析显示该地区沙尘气溶胶反射光谱的一阶导数曲线分别在波长430,560 nm处存在两个明显的特征峰值,可用于指示粉尘样品中的赤铁矿和针铁矿的相对含量.红色、橙色和黄色反射率随赤铁矿和针铁矿可见光谱一阶导数特征值增加而增大,而蓝色、紫色和绿色反射率则相应减小,表明赤铁矿和针铁矿是格尔木沙尘的重要致色矿物,对沙尘气溶胶光学特性产生重要影响.格尔木地区沙尘气溶胶中赤铁矿和针铁矿相对含量变化受沙尘过程影响,沙尘天气时赤铁矿和针铁矿可见光谱一阶导数特征值明显增高,指示铁氧化物的相对含量增高.赤铁矿和针铁矿可见光谱一阶导数特征值及两者比值在不同地区粉尘样品中有很大差异,表明赤铁矿和针铁矿可见光谱一阶导数特征值及两者比值具有较强的源区指示意义.     

华北地区气溶胶的季节垂直分布特征及其光学特性

利用CALIPSO卫星2级产品,分析了华北地区不同污染条件下气溶胶光学厚度(AOD)的时空分布特征,气溶胶的季节成分比例及其光学属性和垂直分布特征.结合AERONET观测数据,对气溶胶的季节光学属性进行了验证.结果表明,华北地区AOD高值区分布于海拔较低的平原地带,低值区主要位于海拔较高的山地丘陵;夏季AOD最大,春季最小;能见度大时AOD小,能见度小时AOD大.华北地区气溶胶以人类活动产生的气溶胶为主,但在春季、秋季、冬季受来自北方的沙尘影响显著;春季退偏振比和色比值最大,夏季最小.春季沙尘被长距离传输至对流层中部及以上区域,夏季强烈的大气垂直对流活动使得大量气溶胶从边界层内被带至自由对流层,秋冬季稳定的气象条件使大量的气溶胶滞留在边界层内.     

阜新市大气污染现状评价

阜新市是以煤炭为主要能源的城市,燃煤加重了大气污染问题.本文采用API空气污染指数法对阜新市1996-2000年大气污染状况进行了评价,分析了污染现状、污染变化的趋势和原因,指出了首要污染物和次要污染物.同时运用综合指数法对2000年阜新市各功能区的大气质量也进行了评价,分析了各功能区的污染现状和污染原因,并提出了解决阜新市大气污染问题的对策.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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