Elements’ Geochemical Characteristics of PM10 and PM2.5 in Beijing During Winter and Spring     

Wang Di  Feng Haiyan  Jing Huimin 《地球科学进展》2017,32(8):850-858

From 2012 to 2013, heavy haze frequently hit Beijing in spring and winter. The fine atmospheric particulates can be inhaled by people, and remain in the respiratory tract and lung for quite a long time. The heavy metal elements in the particles are harmful, and even carcinogenic to human bodies. Therefore, it is necessary to master the geochemical characteristics and the temporal and spatial distribution of the heavy metal elements in atmospheric particles. The atmospheric particulates (TSP/PM₁₀/PM_2.5) were collected by using TH1500C intelligent medium volume (80~120 L/min) air samplers in the five functional areas and suburbs of Beijing, respectively in January 2013 (heating period) and April 2013 (non-heating period). The five functional areas were: building materials factory area, residential area, education area, business area and recreation area, each functional area having three sampling sites, and five in suburbs. The sampling height was 1.5 m above the ground and the distance of the sampling sites to roads exceeded 50 m so as to avoid excessive impact of vehicle exhaust emissions. These samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES)and Atomic Fluorescence Spectrometer (AFS), by which 21 elements including Al, Fe, Mn, As, Hg, Cd, Cr were tested. Based on the comparisons of the concentration and element content variation of atmospheric particulates of these functional areas in and after the heating period, the spatial distribution of atmospheric particulates and the influence of coal combustion on the concentration and composition of atmospheric particulates were revealed. The elements sources of atmospheric particulates were also discussed by computing the enrichment factor of the elements, providing a scientific basis for the air contaminant treatment in Beijing. The results showed that the total concentration of the 21 elements of PM₁₀ and PM_2.5 in the functional areas of Beijing in winter was higher than that in spring, the most marked among them being the business area. In winter, the concentration of pollution elements in the building materials factory area and the business area in Beijing was extremely high, and the residential area, education area, recreation area and suburbs where people live were much better, among which the education area was the best. The concentration change of particulates in suburbs was quite smaller in winter and spring than that of the urban area. It also showed that the concentrations of Cd, Cr, As and Hg in PM₁₀ increased by 233%,306%,298%,141%,respectively and the increase in PM_2.5 was 442%、309%、310%、256%, respectively. These abovementioned elements show a tendency to accumulate mainly in PM_2.5 whose concentrations in winter were significantly higher than those in spring. It indicates that coal heating during winter makes great contributions to the polluting elements in atmosphere and the main polluting particulates are Cd, As and Hg.  相似文献   

A 2.5-D coupled FE–BE model for the dynamic interaction between saturated soil and longitudinally invariant structures     

《Computers and Geotechnics》2017

A two-and-a-half-dimensional (2.5-D) coupled finite element–boundary element (FE–BE) model is presented to simulate the three-dimensional dynamic interaction between saturated soils and structures with longitudinally invariant geometries. A regularized 2.5-D boundary integral equation for saturated porous media is derived that avoids the evaluation of singular traction integrals. The 2.5-D coupled FE–BE model is established by using the continuity conditions on the soil–structure interface. The developed model is verified through comparison with an existing semi-analytical method. Two case studies of a tunnel embedded in a poroelastic half-space and the efficiency of a vibration isolating screen are presented.  相似文献   

Analysis of ground vibrations due to underground trains by 2.5D finite/infinite element approach   总被引：1，自引：1，他引：0  

Hung Hsiao-Hui  Y. B. Yang 《地震工程与工程振动(英文版)》2010,9(3):327-335

The 2.5D finite/infinite element approach is adopted to study wave propagation problems caused by underground moving trains. The irregularities of the near field, including the tunnel structure and parts of the soil, are modeled by the finite elements, and the wave propagation properties of the far field extending to infinity are modeled by the infinite elements. One particular feature of the 2.5D approach is that it enables the computation of the three-dimensional response of the half-space, taking into account the load-moving effect, using only a two-dimensional profile. Although the 2.5D finite/infinite element approach shows a great advantage in studying the wave propagation caused by moving trains, attention should be given to the calculation aspects, such as the rules for mesh establishment, in order to avoid producing inaccurate or erroneous results. In this paper, some essential points for consideration in analysis are highlighted, along with techniques to enhance the speed of the calculations. All these observations should prove useful in making the 2.5D finite/infinite element approach an effective one.  相似文献   

北京市大气PM2.5中多溴联苯醚污染水平与来源分析   总被引：1，自引：1，他引：0  

杨雪  刘大锰  孙俊玲 《现代地质》2010,24(2):355-361

2008年1月、9月和10月在北京城区5个采样点共采集9个大气颗粒物PM_2.5样品。遵循US EPA-1614方法,采用同位素稀释、高分辨气相色谱/高分辨质谱(HRGC/MS)联用技术,测定了大气颗粒物PM_2.5样品中14种多溴联苯醚(PBDEs)的质量浓度,研究了北京市城区大气颗粒物PM_2.5中多溴联苯醚的污染水平、分布特征及来源。结果表明: 9个大气颗粒物PM_2.5样品中PBDEs的质量浓度范围为2.82~57.94 pg/m³,平均值为15.67 pg/m³,BDE-209的质量浓度为0.34~7.32 pg/m³,PM_2.5样品中PBDEs的质量浓度冬季高于秋季;高溴代联苯醚在颗粒物中的含量高,低溴代联苯醚的含量低;交通源对大气颗粒物PM_2.5中PBDEs的污染贡献值很小,工业污染源贡献大于交通源,从含有溴代阻燃剂的物品释放到大气中的PBDEs对大气颗粒物PM_2.5中PBDEs的污染贡献值最大。  相似文献   

银川市PM2.5重金属元素的环境污染特征分析   总被引：7，自引：1，他引：6  

樊曙先  樊韬  严培君  郑有飞  金国兴  陈式功 《中国沙漠》2006,26(2):291-294

分析了银川市PM2.5中9种重金属元素在春季风沙期、夏秋季非采暖期、冬季采暖期的浓度分布特征和富集因子。结果表明：银川市PM2.5中重金属元素的质量浓度在风沙期、非采暖期、采暖期表现不同,Cu,Ni,Mn,Cr,Fe,Cd元素在风沙期浓度最高,Zn,Pb,Co在采暖期浓度最高,说明风沙期和采暖期是银川市一年中的强污染期;重金属元素在不同粒径颗粒物中的浓度水平有明显差别,有害的重金属元素主要吸附在PM2.5中,应引起重视;Zn,Cd元素在各时段都有明显富集,主要来自人为源贡献;Pb元素在采暖期明显富集,说明银川市冬季采暖燃煤的排放对空气中污染元素Pb的贡献很大。  相似文献   

Seismic analysis of underground tunnels by the 2.5D finite/infinite element approach     

《Soil Dynamics and Earthquake Engineering》2016

A procedure for the seismic analysis of underground tunnels using recorded free-field earthquakes based on the 2.5D finite/infinite element approach is presented. The near and far fields of the half space are modeled by finite and infinite elements, respectively. Using the 1D wave theory, the nodal force and displacement on the near-field boundary are computed for each spectral frequency of the earthquake. Then, equivalent seismic forces are computed for the near-field boundary for the earthquake spectrum. By assuming the soil-tunnel system to be uniform along the tunnel axis, the 2.5D approach can account for the wave transmission along the tunnel axis, which reduces to the 2D case for infinite transmission velocity. The horizontal and vertical components of the 1999 Chi-Chi Earthquake (TCU068) are adopted as the free-field motions in the numerical analysis. The maximal stresses and distribution patterns of the tunnel section under the P- and SV-waves are thoroughly studied by the 2.5D and 2D approaches, which should prove useful to the design of underground tunnels.  相似文献   

基于空间面板计量模型的雾霾对中国城市旅游流影响的空间效应   总被引：7，自引：2，他引：7  

徐冬  黄震方  黄睿 《地理学报》2019,74(4):814-830

以中国342个市域单元为研究对象,借助双变量LISA模型、空间面板杜宾模型等方法,探究了1998-2016年雾霾与中国城市旅游流的空间关联特征,分析了雾霾对旅游流的影响及其空间溢出效应。结果表明,在中国雾霾PM_2.5与城市旅游流有东高西低的分布特点,在胡焕庸线两侧的空间分布呈现出与地形和城市发展等因素的空间耦合性;雾霾与城市旅游流（含国内和入境旅游流）均表现出显著的空间集聚和空间依赖特征,雾霾污染对旅游流产生明显的影响并形成相应的空间效应;雾霾对旅游流的抑制区域在不断扩大,H-L型城市数量的增加、L-H型集聚区的片状扩张和华北、华中地区的L-H型集聚的“空心化”现象均表明旅游流具有低雾霾指向性;雾霾污染与旅游流的倒“U”型曲线关系表明经典的EKC假说对中国城市旅游流同样适用,且雾霾污染的显著负向影响主要存在于入境旅游方面;雾霾和旅游流均具有明显的正向空间溢出效应,将雾霾治理同经济发展、对外联系、旅游开发、生态保护和交通建设等因素结合起来进行综合治理,才能为旅游发展创造美好的环境,实现国际、国内旅游健康、协调、可持续的高质量发展。  相似文献   

基于GWR模型的中国城市雾霾污染影响因素的空间异质性研究   总被引：1，自引：2，他引：1  

王少剑  高爽  陈静 《地理研究》2020,39(3):651-668

基于全国城市的PM_2.5监测数据,识别PM_2.5的时空分布特征,并着重利用地理加权回归模型分析自然和社会经济因素对PM_2.5影响的空间异质性。结果显示：2015年全国PM_2.5的年均浓度为50.3 μg/m3,浓度变化呈现冬高夏低,春秋居中的“U型”特征;PM_2.5的空间集聚状态明显,其中京津冀城市群是全国PM_2.5的污染重心。地理加权回归结果显示：影响因素除高程外,其余指标均呈现正负两种效应,且影响程度具有显著的空间差异性特征。从回归系数的贡献均值来看,自然因素对城市PM_2.5浓度影响强度由高到低依次是高程、相对湿度、温度、降雨量、风速、植被覆盖指数;各类社会经济指标对城市PM_2.5浓度影响强度排名依次是人口密度、研发经费、建设用地比例、产业结构、外商直接投资、人均GDP。由于各指标对城市PM_2.5浓度变化的影响程度存在着空间异质性,因此在制定大气治理对策时可以考虑不同指标影响程度的空间差异,从而使得治霾对策更具针对性。  相似文献   

东北地区大气污染物源排放时空特征：基于国内外清单的对比分析   总被引：2，自引：0，他引：2  

张萌铎  陈卫卫  高超  张学磊  姜怡冰  修艾军 《地理科学》2020,40(11):1940-1948

基于国内外4类常用的污染源排放清单数据（EDGAR：全球大气研究排放数据库；CEDS：社区排放数据系统；MIX：亚洲排放清单；PKU-FUEL：全球燃料排放数据），对东北区域5类人为排放源（工业源、能源、交通运输源、生活民用源和农业源）的8种污染物（PM_2.5、PM₁₀、SO₂、NO_x、NMVOCs、NH₃、OC和BC）从排放总量、来源贡献和时空分布特征等方面进行对比分析。结果表明：东北污染物排放主要以SO₂、NO_x和NMVOCs为主，工业、能源和交通运输为主要贡献源；PM_2.5和PM₁₀主要来自生活民用源和工业源，贡献率前者大于后者。辽宁省污染物（除NH₃外）排放最大，其次为黑龙江省、吉林省和内蒙古东四盟市，冬季排放强度明显高于其他季节。NH₃主要来自农业源，排放峰值发生在5~7月；各清单间排放总量和来源贡献差异明显，EDGAR和PKU清单对NH₃估算差异度为170.3%；SO₂、NO_x、BC和OC的排放差异度均在30%以上。不同活动水平和排放因子的使用是造成清单差异的主要原因。本研究可以掌握东北污染状况，了解清单差异，为本地化清单工作开展提供研究方向，同时也可为模式模拟合理选择清单数据提供参考。  相似文献   

济南PM2.5质量浓度与气象条件相关性初步研究          下载免费PDF全文

黄善斌  李本轩  王文青 《山东气象》2020,40(1):90-97

通过对济南2013年12月—2018年2月PM2.5质量浓度数据分析得出,PM2.5质量浓度平均和最大值均为冬季最高,春秋季次之,夏季最低;PM2.5质量浓度值1月和12月最高,8月最低;其质量浓度呈明显的逐年递减趋势。在不同风向上PM2.5质量浓度存在显著差异性,在N风向和ESE(盛行)风向上均出现了质量浓度较大值,一方面与污染物的异地输送有关,另一方面与济南的特殊地形有关。研究表明,无论污染源在山脉的背风侧还是迎风侧,都很容易导致高浓度污染;尤其在冬季,山脉地形还会加重逆温影响,使污染程度加重。通过相关性研究发现,冬季、春季和秋季,PM2.5质量浓度与相对湿度和平均总云量均呈正相关,与日照时数及其距平呈负相关;冬季,PM2.5质量浓度与平均气温及其距平以及最高、最低气温均呈正相关,与平均、最高、最低气压均呈负相关;春季和秋季,PM2.5质量浓度与气温距平值呈正相关;夏季和秋季,PM2.5质量浓度与日降水量呈负相关,而且随着雨强的增大,对PM2.5的洗消作用越显著。上述变量间相关性均通过了P≤0.01显著性检验。  相似文献