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1.
Studies on composition and distribution of dust deposition are necessary for the risk assessment of dust to atmospheric quality. We studied the vertical distribution pattern of dust and metal (Cu, Fe, Pb, Zn) deposition up to 33 m height in urban environment. Integrated geochemical, mineralogical and magnetic study of the seasonally sampled dust helped to specify our knowledge on the use of magnetic susceptibility for tracking its deposition. Harmful dust and metal deposition may occur even at great heights and at the low-traffic side of buildings. Re-suspension of local surface materials dominates the dust deposition primarily in summer and spring due to weather conditions, and it may overwrite the influence of recent anthropogenic activities on dust composition. The accepted air-flow models should be modified by taking the local conditions (weather, morphology, etc.) into account. All studied metals showed strong enrichment in the dust and could be characterized by similar vertical deposition pattern to dust. The total susceptibility was found to be much more useful proxy for tracking dust and metal deposition than mass-specific susceptibility. Using the former, potential errors arising from sampling practice of settled dust could be eliminated. The most important heavy-metal-bearing phases were iron oxides and clay minerals. Their different behavior during the dust deposition is reflected by the vertical metal distribution patterns. Clay minerals originate primarily from re-suspension and may be one of the most important sources of potentially mobile heavy metals in such materials.  相似文献   

2.
Summary The generation and transportation of airborne dust is governed mainly by the velocity and the movement pattern of the ventilation air in longwall faces. Generally speaking, the higher the air velocity, the more airborne dust will be generated and the further dust of a given size will be carried away from the source. In order to effectively prevent or reduce the production and spread of the airborne dust, the airborne dust concentration distribution at a longwall face must be known in advance. This paper presents the measurement methodology, data analyses and dust distributions in five longwall faces.  相似文献   

3.
依据粒度分析、电镜扫描、能谱分析、常温水溶盐检测、宏观表象特征研究和实地调查，证实北京2006年4月16日的所谓“沙尘暴”是尘暴，干涸盐湖是京津尘暴的重要源区。因此，要治理京津地区的尘暴，就必须修复干涸盐湖区的生态环境，而不能像过去那样去治理沙漠。要修复干涸盐湖区的生态环境，一定要用现代生态环境地质学的理论和方法去研究干涸盐湖区在地质历史时期植被演化的趋势，筛选出最适合当地生态环境的土著先锋植物种群，并用土著先锋植物种群对尘源区进行“地毯式”的覆盖，而不能用种树去阻挡它，因为再高的树林也挡不了从2000-3000m以上高空飘来的浮尘。  相似文献   

4.
Grain-size distributions and detrital minerals were investigated for modern dust and for lacustrine sediment in Lake Barkol region, northwest China. Characteristics of the modern dust and lacustrine sediments, principle component analysis, and changes of quartz contents all suggest grain size 45–138 μm in the core sediment is the dust sensitive component. It indicates that high dust flux climate occurred at mid-Holocene (5.5–4.5 cal ka BP), corresponding to the high dust flux record in northwest Pacific and the drought interval of deserts in northwest China during the mid-Holocene. The strong dust activity is in contradiction with the climatic optimum recorded by the lacustrine evidence in Xinjiang. Different responses of the dust source region and watershed to the regional climate may have led to the inconsistency between dust and climate records during the mid-Holocene in arid central Asia.  相似文献   

5.
Windblown mineral aerosol dust derived from the crustal surface is an important atmospheric component affecting the earth’s radiation budget. Deposition of atmospheric dust was measured in the fresh snow on glacier no. 1 at the headwater of the Urumqi River in eastern Tian Shan, central Asia. An analysis of seasonal variation of concentrations of dust particles in the snow suggests that the number concentration of dust particle is significantly high from April to June, which may be caused by Asian dust storms in the spring. The comparison of mass-size distribution of dust particles from April to August shows an obvious seasonal change trend. The distribution of particles changes from single model (3–21 μm) in the non-dust period before dust events in April, to bi-model (3–21 and 20–80 μm) during the Asian dust period, and to single model (3–21 μm) after July in the non-dust period again. The Ca2+ concentration in the fresh snow is also very high from April to June, while NH4 + and SO4 2−, as water-soluble constituents, have concentration changes that are different from each other. Backward trajectory was also employed to examine the transport process of air mass in this region.  相似文献   

6.
Radiocarbon-dated sediment cores from subalpine lakes were used to investigate post-glacial dust deposition in the Uinta Mountains (Utah, USA). Lake sediments were geochemically characterized with ICP-OES, ICP-MS and XRF core scanning. Collections from passive samplers constrain the properties of modern dust, and samples of regolith constrain properties of the local material within the watershed. Ca and Eu are more abundant in dust, whereas Ti and Zr are more abundant in local regolith. As a result, the Ca/Ti and Eu/Zr ratios are indices for the dust content of lake sediment. In all records, the dust index rises in the early Holocene as watersheds became stabilized with vegetation, reducing the influx of local material. After this point, values remained above average through the middle Holocene, consistent with an increased dust content in the sediment. Dust index values drop in the late Holocene in most lakes, suggesting a decrease in dust abundance. Generally synchronous shifts in dust index values in cores from lakes in different parts of this mountain range are evidence of enhanced dust deposition in this region during the middle Holocene, and are consistent with a variety of records for increased aridity in the south-western USA at this time.  相似文献   

7.
Besedina  Yu. N.  Popel  S. I.  Shukla  P. K. 《Doklady Earth Sciences》2009,429(1):1407-1410
Redistribution of dust particles in the ionosphere as a result of vortical motions is discussed. The following possibilities are studied: capture and evolution of dust particles in acoustic-gravitational (AG) vortices, formation of dust vortices as a result of involving a great number of dust particles into vortex motions, and formation of vertical dust flows (streamers). It is shown that excitation of AG-vortices at altitudes of 110–130 km as a result of development of AG-wave instability, associated with non-zero balance of heat fluxes, owing to solar radiation, water vapors condensation, infrared emission of the atmosphere, and thermal conductivity, leads to a substantial transportation of dust particles and their mixing at altitudes of 110–120 km. Layers of dust particles in the ionosphere with a thickness of about a kilometer, forming at altitudes less than 120 km, distribute within the region of existence of AG-vortical structures. As a result, at altitudes of 110–120 km, dust vortices can appear, and transportation of particles up to altitudes of 130 km becomes possible. One of the ways of transportation of dust particles in the ionosphere is vertical flows (streamers), which are generated by dust vortices as a result of development of parametric instability.  相似文献   

8.
《地学前缘(英文版)》2020,11(3):783-792
Geogenic dust is commonly believed to be one of the most important environmental problems in the Middle East.The present study investigated the geochemical characteristics of atmospheric dust particles in Shiraz City(south of Iran).Atmospheric dust samples were collected through a dry collector method by using glass trays at 10 location sites in May 2018.Elemental composition was analysed through inductively coupled plasma optical emission spectrometry.Meteorological data showed that the dustiest days were usually in spring and summer,particularly in April.X-ray diffraction analysis of atmospheric dust samples indicated that the mineralogical composition of atmospheric dust was calcite+dolomite(24%)palygorskite(18%)quartz(14%)muscovite(13%)albite(11%)kaolinite(7%)gypsum(7%)zircon=anatase(3%).The high occurrence of palygorskite(16%-23%) could serve as a tracer of the source areas of dust storms from the desert of Iraq and Saudi Arabia to the South of Iran.Scanning electron microscopy indicated that the sizes of the collected dust varied from 50 μm to0.8 μm,but 10 μm was the predominant size.The atmospheric dust collected had prismatic trigonal-rhombohedral crystals and semi-rounded irregular shapes.Moreover,diatoms were detected in several samples,suggesting that emissions from dry-bed lakes,such as Hoor Al-Azim Wetland(located in the southwest of Iran),also contributed to the dust load.Backward trajectory simulations were performed at the date of sampling by using the NOAA HYSPLIT model.Results showed that the sources of atmospheric dust in the study area were the eastern area of Iraq,eastern desert of Saudi Arabia,Kuwait and Khuzestan Province.The Ca/Al ratio of the collected samples(1.14) was different from the upper continental crust(UCC) value(UCC=0.37),whereas Mg/A1(0.29),K/Al(0.22) and Ti/Al(0.07) ratios were close to the UCC value(0.04).This condition favours desert calcisols as the main mineral dust sources.Analysis of the crustal enrichment factor(EF_(crustal)) revealed geogenic sources for V,Mo,Pb,Sr,Cu and Zn(2),whereas anthropogenic sources affected As,Cd,Cr and Ni.  相似文献   

9.
Kuwait is an arid country with an annual average rainfall of about 110 to 120 mm. Hence, dust storms have become a common environmental crisis. Although the dry summer months commonly have more dust storms, in recent years, dust storms occur more frequently in the spring season as well. Accumulated data of dust storms in Kuwait for the past 14 years (2001–2014) showed that the month of March had the highest number of dust storms (total 19), which is rather unusual, with an average of 8 dust storms per year (year 2008 had the highest dust storms of total 22). This study explored four socioeconomic effects of dust storms in Kuwait, specifically traffic accident rates, oil export loss due to close out of marine terminals, airline delays due to airport operation shutdown, and agriculture degradation. Statistical analysis using t test and Pearson correlation showed no apparent relationship between dust storms and traffic accident rates or agricultural production; however, loss of oil export and flight delay cost were affected by dust storms. There has been very few published research on the socioeconomic impact of dust storms; this is the first paper that explores the detailed socioeconomic effect of dust storms in Kuwait.  相似文献   

10.
北京的"沙尘暴"在地质学研究分类中应属于尘暴,且属含大量盐碱物质(水溶盐物质)的盐碱尘暴。盐碱尘暴对人体健康和经济发展造成严重威胁,已引起普遍关注。通过调查北京尘暴源区蒙古国东南部和中国内蒙古中部、河北省西部地区表土和部分降尘的理化特性,为探讨北京盐碱尘暴粉尘物质的来源提供新的证据。对尘源区农耕地、沙化土地、退化草地、撂荒地、沙漠、沙地等不同代表性区域的表土进行较系统的采样,收集北京和部分尘源区附近城镇的大气降尘,分析其水溶盐和水溶性元素或离子的含量、酸碱度、粒度、比重、起尘风速。结果表明,干盐湖盆区以高百分含量的细微粉尘物质(200目)、水溶盐含量和部分水溶性元素或离子(如Na、Cl-)为主要特征,其较高的pH值、极小的粒径、很大的比表面积、偏小的比重、偏低的起尘风速等,与北京及尘源区附近城镇大气降尘的特性相对应,明显不同于沙漠、沙地、沙堆和农耕地、撂荒地、退化草地等,因此推测干盐湖盆区是现阶段北京盐碱尘暴最主要、最关键的源区之一。而水溶盐含量、粒度大小、酸碱度、比重、起尘风速等,是判断北京盐碱尘暴粉尘物质来源的关键性指标。  相似文献   

11.
Street dust is a potential source of lead exposure to humans, however scarce information about the pollution levels with lead and polyromatic hydrocarbons exists in Venezuela, limiting the appropriate evaluation of the levels of risk of the people. This work was aimed in the determination of the concentrations of lead, naphtalene, anthracene, phenanthrene and pyrene in the street dust of the most transited avenues and streets of Maracay city. Thirty street dust samples were collected at the streets and avenues, troll and bus main station. Lead was determined by atomic absorption spectrometry after acid digestion (Pb-total), also the fractions of lead soluble in 1 M MgCl2 and 0.5 M ammonium acetate (pH = 7) were quantified. The polyaromatic hydrocarbons concentrations were determined by capillary gas chromatography equipped with a flame ionization detector. The Pb-total ranged between 734 and 11.439 μg/g with the higher values at the most transited streets and avenues. About 60 % of samples exhibited concentrations between 1.000 and 2.500 μg/g, similar to the values reported in the literature for soils of urban areas. The fraction of lead soluble in magnesium accounted for less than 3 % of Pb-Total, while the 0.5 M ammonium acetate solution represented more than the 75 % of the total loads of the pollutant. The most contaminated samples were those taken at the toll with concentrations of 695.5 and 252.1 μg/g phenanthrene and anthracene were the most abundant, while at the bus station all compounds were detected.  相似文献   

12.
The entrainment, transport and deposition of æolian dust are important processes affecting soil development at the margins of deserts. To assess accurately the impact of deposited æolian dust on soil development, it is important not only to measure total dust deposition rates, but to distinguish additions of remotely and regionally sourced dust from locally derived material as well (which should not be viewed as new soil material as it is derived from æolian re‐mobilization of an existing soil). Because of the well‐established relationship between dust particle‐size and distance travelled from source, the particle‐size distribution of deposited dusts can be used to identify the distance to probable source regions, in addition to identifying matching topsoil particle populations. Three dust traps were located along a transect of semi‐arid south‐eastern Australia, to measure æolian dust deposition rates between late 2000 and late 2001. The particle‐size distributions of selected dust deposits were measured and, with the aid of meteorological data, probable dust source regions determined. Particle‐size distributions of the topsoils at each dust trap location were also measured to determine if any dust and soil particle populations matched. Although the sampling period was relatively short, and there was relatively little dust storm activity in this part of Australia during this time, a clear pattern of diminishing total dust deposition was measured downwind along the south‐east dust path. Dust deposition rates were also moderate to low by global standards. Source regions of deposited dust were interpreted as being: (i) a combination of south‐western and local sources; (ii) a combination of north‐western and local sources; and (iii) a mixed source where dust was rained‐out. The relative importance of these sources was correlated strongly with seasonal weather conditions, although the proportion of local dust in each deposit was greater at the arid (western) end of the transect. The effects of deposited dust on soil profile development are greatest at the western and central transect locations. At the western location, a fine‐grained particle population distinctive of the south‐western and north‐western regional dusts and a coarse silt‐sized particle population characteristic of local dusts, are also present in the topsoil, altering the texture of this Arenosol derived from dune sand. At the central location, where a Calcisol has formed in lacustrine lunette sediment, local dust of the same size as the dominant silt population of the topsoil continues to be deposited, while minor topsoil populations of very fine‐grained silt match regional and long‐distance dusts deposited at the site. Deposited dust appears to have been a less important soil development factor at the more humid eastern site because of the much smaller rates of dust deposition there. Nevertheless, a minor population of very fine silt particles in the Vertisol topsoil matches long‐distance dusts deposited at the site, suggesting a small input of dust to this alluvial soil. The particle‐size methodology used here has applications in other studies of dust contributions to peri‐desert soils. In particular, particle‐size distribution ‘smoothness’ may provide an indication of whether soils have simple or complex origins.  相似文献   

13.
We consider the interaction of interstellar dust grains with a galactic shock in the gaseous component. Typical parameters of dust grains and spiral density waves imply that the formation of large-scale dust lanes at the front of a galactic shock is possible only in models taking into account a self-focusing phenomenon. In the case of an isothermal flow of interstellar gas through a spiral arm in a model with a gaseous disk of variable thickness, dust lanes can be projected onto the region of increased gas density, although this is not associated with a galactic shock. The dust density peak derived from the classical model of a galactic shock (isothermal flow and a constant thickness of the gaseous disk) is appreciably shifted downstream of the gas flow, so that it does not outline the gas density maximum.  相似文献   

14.
为探究绿洲城市道路积尘重金属污染风险,在新疆库尔勒市采集54个代表性道路积尘样品,分析其中Hg、Cd、As、Pb、Cr和Cu等6种元素含量,基于GIS技术与地学统计法,采用污染负荷指数法和US EPA健康风险评价模型,对道路积尘中重金属污染及潜在健康风险进行评价。结果表明：库尔勒市道路积尘中Hg、Cd、As、Pb和Cu等元素含量的平均值均小于土壤环境质量—建设用地土壤污染风险管控标准（GB 36600—2018）中的筛选值,但Cr元素含量平均值为相应筛选值的9.90倍。污染评价结果表明,研究区道路积尘中Cr呈现重度污染,Hg、Cd、As、Pb和Cu呈无污染。道路积尘中重金属元素的污染负荷指数介于0.0142~0.0522,平均值为0.0266,处于无污染水平。从道路积尘重金属污染空间分布格局来看,库尔勒市东北部和北部区域出现污染高值区。健康风险评估结果表明,经手-口摄入途径是库尔勒市道路积尘重金属日均暴露量及健康风险的主要途径,儿童受到的健康风险高于成人。库尔勒市道路积尘中Hg、Cd、As、Pb、Cr与Cu等元素的非致癌风险及致癌风险处于安全范围内,As对非致癌风险的贡献最大,Cr对致癌风险的贡献最大。  相似文献   

15.
The paper addresses influence of dust particles on the aerosol loading over the major deserts in the northern hemisphere. The role of dust aerosols in the total aerosol concentration and size distribution of the particles are analysed. It is observed that the aerosol loading is high in the northern hemisphere of which the deserts and adjoining areas in Asia and Africa play a leading role. Over the entire oceanic region, except some parts of the Atlantic Ocean near to the West coast of Africa and the Arabian Sea, aerosol loading is less. The Sahara Desert is the prominent source of dust aerosols throughout the year. The deserts of Asia are also prominent sources of dust aerosols on a global basis. Above 70% of the total aerosol optical depth (AOD) is contributed by the dust particles, reaching to around 90% during spring months March, April and May over the Sahara Desert, which is the major source of dust aerosols. Goddard Chemistry Aerosol Radiation and Transport model is used to estimate the dust aerosol concentration over the deserts of Asia and Africa. The model output almost agrees with the regions of dust loading obtained from the Envisat/SCIAMACHY. Hence, the model is reliable in estimating the dust aerosol loading over the major dust aerosol sources. The major portion of the total dust loading belongs to coarse mode particles.  相似文献   

16.
Cometary grains containing large amounts of carbon and/or organic matter (CHON) were discovered by in situ measurements of comet Halley dust composition during VEGA and GIOTTO flyby missions. In this paper, we report the classification of these cometary grains by means of cluster analysis, discuss the resulting compositional groups, and compare them with substances observed or hypothesized in meteorites, interplanetary dust particles, and the interstellar medium. Grains dominated by carbon and/or organic matter (CHON grains) represent approximately 22% of the total population of measured cometary dust particles. They usually contain a minor abundance of rock-forming elements as well. Grains having organic material are relatively more abundant in the vicinity of the nucleus than in the outer regions of the coma, which suggests decomposition of the organics in the coma environment. The majority of comet Halley organic particles are multicomponent mixtures of carbon phases and organic compounds. Possibly, the cometary CHON grains may be related to kerogen material of an interstellar origin in carbonaceous meteorites. Pure carbon grains, hydrocarbons and polymers of cyanopolyynes, and multi-carbon monoxides are present in cometary dust as compositionally simple and distinctive components among a variety of others. There is no clear evidence of significant presence of pure formaldehyde or HCN polymers in Halley dust particles. The diversity of types of cometary organic compounds is consistent with the interstellar dust model of comets and probably reflects differences in composition of precursor dust. Preservation of this heterogeneity among submicron particles suggests the gentle formation of cometary nucleus by aggregation of interstellar dust in the protosolar nebula without complete mixing or chemical homogenization at the submicron level.  相似文献   

17.
《Quaternary Science Reviews》2003,22(18-19):1821-1834
Soil dust aerosol is an important factor of the climatic system. In order to evaluate the different aspects of the climatic effects of dust, estimates of its highly variable atmospheric distribution need to be computed by transport models. Such models also provide important means of evaluating the processes that govern changes in dustiness during different climatic periods. While models of the modern dust cycle are currently capable of simulating first-order patterns of its global distribution, the parameterization of dust emission in these models is still crude, since input information about soil properties and wind events cannot be resolved at a global scale. Regional models could be useful for evaluating emission parameterizations, as well as dust transport and depositional processes close to source regions. No single existing data set fully describes all aspects of the dust cycle. Validation of modeled dust distributions must therefore include comparisons with different types of observational data. While the compilation of such observational data sets is crucial for model development, model results can, in turn, provide guidance for new measurements of dust properties, which will be useful for future investigation of the dust cycle and its climatic effects.  相似文献   

18.
内蒙古乌海粉尘浓度时空分布及影响因素探析   总被引：1，自引：0，他引：1  
于2018年1月与7月采用流动监测法,对内蒙古乌海粉尘颗粒物进行采集,结合监测站数据,研究乌海不同粒径粉尘浓度时空分布规律及影响因素。结果表明:乌海市冬春季粉尘污染远远高于夏秋季,春季污染最严重,夏季污染相对较轻。PM2.5污染最严重月份为3月,PM10污染最严重月份为4月。一天中粉尘浓度峰值出现在10:00—12:00,谷值出现在16:00—18:00。空间上东部粉尘浓度高值区以条带状分布,中南部和西部以点源放射状向周围扩散。不同土地利用类型内部粉尘浓度特征均不同。工矿用地和城镇内部浓度高于有林地和未利用地,耕地和水体内部浓度最低;工矿用地是乌海市粗颗粒粉尘的主要来源,城镇是乌海夏季细颗粒粉尘的主要来源,水体、耕地和有林地可明显降低空气中颗粒物浓度。总悬浮颗粒物(total suspended particulate,TSP)和不同粒径颗粒物(particulate matter,PM),包括PM10、PM2.5、PM1等粉尘浓度与风速、湿度呈正相关,与温度、海拔呈负相关,其中气压是影响TSP浓度的最主要因素,湿度是影响PM1-10的最主要因素。不同粒径粉尘浓度受到归一化指数、气象、地形等多因素综合制约,单一条件对大气粉尘影响有限。  相似文献   

19.
Design and Implementation of Space Dust Database   总被引：2，自引：0，他引：2  
Space debris is very dangerous to the security of on-the-orbit spacecrafts, and it is increasing in number at high speed with the expansion of human space exploration. Space debris has become a serious space pollutant noticed by many astronomers. The increase of space dust sources and the development of research on space dust urgently need space dust data sharing and exchanging. It is necessary for us to establish the Space Dust Database to realize the sharing and canonical management of the data. The Space Dust Database (SDD) management system,based on the 3-layer B/S computer mode, was designed and implemented in this paper. The system‘s features include significantly improved runtime efficiency, good scalability and maintainability. The Space Dust Database can pTovide some scientific bases for the study of the chemical constituents, mineral composition, origin and sources of space dust, but also provide excellent data services and decision-making support for the protection of space and model construction of space dust.  相似文献   

20.
The volcanic origin, primarily basaltic, of most of the surface material in Iceland influences its physical properties and appearance. Size distributions, shape analyses and melting experiments were made for surface material collected in high-erosion dust source areas and fresh volcanic ash deposits to determine whether they differ from one another and from dust from other major dust sources. The major differences found between Icelandic dust and dust from other major dust sources in the world, such as the Sahara, are in the particle shapes, lower density and darker colour. Icelandic dust particles greater than 20 μm retain volcanic morphological properties that are also found in fresh volcanic ash. Dust and fresh volcanic ash particles less than 20 μm are crystalline and blocky in nature, similar to the dust from other global source regions. The finer grained (<20 μm) Icelandic particles will have similar suspension and transport behaviours and be similarly hazardous to health and infrastructure as non-Icelandic dust. The coarser particles (>20 μm) will have different suspension and transport behaviours than other dusts due to the volcanic morphology. Icelandic surface material has between 5% and 30% glassy particles compared to fresh volcanic ash which has more than 50% glassy particles. Glassy particles were observed to melt at a lower temperature than the mineral grains; and, as a result, volcanic ash is found to be more threatening to aircraft engines than the typical dust from Iceland. Icelandic dust was observed to be blocky, or plate-like in the respirable size fraction, suggesting similar health hazards as dust from other regions.  相似文献   

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