WorldWideScience

Sample records for dust sources spatially

  1. Sand-dust storms in China: temporal-spatial distribution and tracks of source lands

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Sand-dust storm is a special natural disaster that frequentlyoccurs in deserts and their surrounding areas. With the data published on Surface Meteorological Monthly Bulletin and Surface Chart during 1971-1996, the temporal-spatial distribution and annual variation of sand-dust storms are analyzed on the basis of the case study of atmospheric processes. Furthermore, the tracks and source areas of sand-dust storms are determined with the aid of GIS. The results show that except some parts of Qinghai Province and Inner Mongolia as well as Beijing, sand-dust storms decrease apparently in time and space in recent decades in China. Sand-dust storms occur most frequently in spring, especially in April. According to their source areas, sand-dust storms are classified into two types, i.e., the inner-source and outer-source sand-dust storms. Most of the outer-source sand-dust storms move along the north and west tracks. The north-track outer-source sand-dust storms always intrude into China across the Sino-Mongolian border from Hami, a city in the eastern part of Xinjiang, to Xilin Gol, a league in Inner Mongolia, while the west-track ones intrude into China from both southern and northern Xinjiang. The source lands of inner-source sand-dust storms concentrate in the Taklimakan Desert and its surrounding areas in southern Xinjiang, southern part of the Junggar Basin in north of Xinjiang, the Hexi Corridor in western Gansu Province, the dry deserts of Inner Mongolia and the Qaidam Basin in Qinghai.

  2. PERSPECTIVE: Dust, fertilization and sources

    Science.gov (United States)

    Remer, Lorraine A.

    2006-11-01

    fraction that arrives at another continent [2]. At the deposition end of the chain, it is still unclear how the limited minerals in the dust such as iron are released for uptake by organisms either on land or in the ocean. Not all dust deposited into oceans results in a phytoplankton bloom. The process requires a chemical pathway that mobilizes a fraction of the iron into soluble form. Meskhidze et al [3] show that phytoplankton blooms following dust transport from the Gobi desert in Asia into the Pacific ocean result in a phytoplankton bloom only if the dust is accompanied by high initial SO2-to-dust ratios, suggesting that sulfuric acid coatings on the dust particle mobilize the embedded iron in the dust for phytoplankton uptake. Quantifying transport, deposition and nutrient availability are the latter ends of a puzzle that must begin by identifying and quantifying dust emission at the sources. The emission process is complex at the microscale requiring the right conditions for saltation and bombardment, which makes identification and inclusion of sources in global transport models very difficult. The result is that estimates of annual global dust emissions range from 1000 to 3000 Tg per year [4]. Even as global estimates of dust emissions are uncertain, localizing the sources brings even greater uncertainty. It has been recognized for several years that dust sources are not uniformly distributed over the arid regions of the Earth, but are regulated to topographic lows associated with dried lake deposits [5]. Using aerosol information from satellites, a comprehensive map of the world's source regions shows sources localized to specific areas of the Earth's arid regions [6]. Still these maps suggest broad emission sources covering several degrees of latitude and longitude. In the paper by Koren and co-authors [7] appearing in this issue, one particular dust source, the Bodélé depression in Chad, is analyzed in detail. They find that the specific topography of the

  3. Identifying sources of aeolian mineral dust: Present and past

    Science.gov (United States)

    Muhs, Daniel R; Prospero, Joseph M; Baddock, Matthew C; Gill, Thomas E

    2014-01-01

    Aeolian mineral dust is an important component of the Earth’s environmental systems, playing roles in the planetary radiation balance, as a source of fertilizer for biota in both terrestrial and marine realms and as an archive for understanding atmospheric circulation and paleoclimate in the geologic past. Crucial to understanding all of these roles of dust is the identification of dust sources. Here we review the methods used to identify dust sources active at present and in the past. Contemporary dust sources, produced by both glaciogenic and non-glaciogenic processes, can be readily identified by the use of Earth-orbiting satellites. These data show that present dust sources are concentrated in a global dust belt that encompasses large topographic basins in low-latitude arid and semiarid regions. Geomorphic studies indicate that specific point sources for dust in this zone include dry or ephemeral lakes, intermittent stream courses, dune fields, and some bedrock surfaces. Back-trajectory analyses are also used to identify dust sources, through modeling of wind fields and the movement of air parcels over periods of several days. Identification of dust sources from the past requires novel approaches that are part of the geologic toolbox of provenance studies. Identification of most dust sources of the past requires the use of physical, mineralogical, geochemical, and isotopic analyses of dust deposits. Physical properties include systematic spatial changes in dust deposit thickness and particle size away from a source. Mineralogy and geochemistry can pinpoint dust sources by clay mineral ratios and Sc-Th-La abundances, respectively. The most commonly used isotopic methods utilize isotopes of Nd, Sr, and Pb and have been applied extensively in dust archives of deep-sea cores, ice cores, and loess. All these methods have shown that dust sources have changed over time, with far more abundant dust supplies existing during glacial periods. Greater dust supplies in

  4. Source apportionment and spatial-temporal variations in the metal content of surface dust collected from an industrial area adjoining Delhi, India.

    Science.gov (United States)

    Pathak, Aditya Kumar; Yadav, Sudesh; Kumar, Pawan; Kumar, Rakesh

    2013-01-15

    Surface dust collected during three different seasons from Faridabad industrial area adjoining Delhi is studied for different metals, their spatial and temporal variations, and sources. Al, Fe, Mn, Ti, Ca and Mg show limited variations and lower abundances compared to Upper Continental Crust (UCC); Fe shows enrichment and seasonal changes. Cd, V, Co, Ba, Ti, Ni, Cu, Cr and Zn show significant spatial and temporal variations, and enrichments compared to UCC indicate their anthropogenic sources. Seasonal variability could be due to: 1) different types of industries, 2) variations in the emissions, 3) very frequent shifting of small scale industry within the region, and 4) changes in the land use pattern. The sampling sites, according to the geo-accumulation index, are: 1) least polluted for Ca, Mg, Al and Ti except for Ti in winter, 2) least to moderately polluted for Ba, Co and V but season specific, and 3) moderately to extremely polluted for other metals. Average pollution load index of 2.67-2.87 indicates consistently high level of pollution at all sites in all sampling seasons. The sites located in the residential areas near small to medium scale unorganized industry are more polluted compared to sites near large industries suggesting that the small scale unorganized industries causes more pollution. Three dominant sources of metals were identified: 1) mixed industrial, 2) crustal, and 3) vehicular, oil and battery related burnings. The third component related to Ba, Pb, Cd, Zn and Cr, further splits into two components in the pre-monsoon and winter samples. Surface dust, enriched in metals, is likely to cause serious danger to public health. There is an urgent need to make a shift from unorganized to formally organized industry to reduce the metal pollution and protect human health and environment as a whole.

  5. Elemental tracers for Chinese source dust

    Institute of Scientific and Technical Information of China (English)

    张小曳; 张光宇; 朱光华; 张德二; 安芷生; 陈拓; 黄湘萍

    1996-01-01

    The mass-particle size distributions of 10 dust-carrying elements in aerosol particles were determined tor 12 sites in desert regions of northern China. The desert dust is proved to he of origin of eolian loess deposited on the Loess Plateau. Their transport to the loess was mainly attributable to the non-dust storm processes under the interglacial climate condition. The impact ot" dust storm on the accumulation of the loess increased in the glacial stage. On the basis of the signatures of 4 dust elements (Al. Fe, Mg and Sc). Chinese dust is believed to have 3 major desert sources (northwestern deserts, northern high dust deserts and northern low dust deserts). With a chemical element balance model, an elemental tracer system is established to proportion the export of China-source dust.

  6. E ring dust sources: Implications from Cassini's dust measurements

    Science.gov (United States)

    Spahn, Frank; Albers, Nicole; Hörning, Marcel; Kempf, Sascha; Krivov, Alexander V.; Makuch, Martin; Schmidt, Jürgen; Seiß, Martin; Miodrag Sremčević

    2006-08-01

    The Enceladus flybys of the Cassini spacecraft are changing our understanding of the origin and sustainment of Saturn's E ring. Surprisingly, beyond the widely accepted dust production caused by micrometeoroid impacts onto the atmosphereless satellites (the impactor-ejecta process), geophysical activities have been detected at the south pole of Enceladus, providing an additional, efficient dust source. The dust detector data obtained during the flyby E11 are used to identify the amount of dust produced in the impactor-ejecta process and to improve related modeling [Spahn, F., Schmidt, J., Albers, N., Hörning, M., Makuch, M., Seiß, M., Kempf, S., Srama, R., Dikarev, V.V., Helfert, S., Moragas-Klostermeyer, G., Krivov, A.V., Sremčević, M., Tuzzolino, A., Economou, T., Grün, E., 2006. Cassini dust measurements at Enceladus: implications for Saturn's E ring. Science, in press]. With this, we estimate the impact-generated dust contributions of the other E ring satellites and find significant differences in the dust ejection efficiency by two projectile families - the E ring particles (ERPs) and the interplanetary dust particles (IDPs). Together with the Enceladus south-pole source, the ERP impacts play a crucial role in the inner region, whereas the IDP impacts dominate the particle production in the outer E ring, possibly accounting for its large radial extent. Our results can be verified in future Cassini flybys of the E ring satellites. In this way poorly known parameters of the dust particle production in hypervelocity impacts can be constrained by comparison of the data and theory.

  7. Satellite based Observations of Saharan Dust Source Areas - Comparison and Variability

    Science.gov (United States)

    Schepanski, K.; Tegen, I.; Macke, A.

    2012-04-01

    Satellite remote sensing products such as Meteosat Second Generation (MSG) Infra Red (IR) dust index and Ozone Monitoring Instrument (OMI) Aerosol Index (AI) are commonly used to infer dust source areas. We compare two different methods for dust source identification, (1) a "back-tacking" method applied to 4 years of 15-minute MSG IR dust index, and (2) a "frequency" method applied to daily OMI AI and daily MODIS DeepBlue Aerosol Optical Thickness (AOT) data for the same time period. Using the "back-tracking" method, dust source areas are inferred by tracking individual dust plumes back to their place of origin, allowed by the high temporal resolution of the MSG images. OMI AI and MODIS Deep Blue AOT products are available on daily resolution only, which disables for back-tracking of individual dust plumes. Thus, dust source areas are retrieved by relating the frequencies of occurrence of high dust loadings to source areas. The spatial distribution of inferred dust source areas from the two methods shows significant differences. The MSG back-tracking method highlights frequent dust emission from sources within complex terrain, while frequencies of high OMI AI values emphasise topographic basins as important dust source areas. Dust source areas retrieved from DeepBlue AOTs are generally placed further south towards the Sahel region. This study shows that the temporal resolution of satellite dust products is a key issue in retrieving dust source areas. Both, the spatial distribution of dust sources and their annual cycle strongly depend on the acquisition time related to the start of dust emission.

  8. Subregional inversion of North African dust sources

    Science.gov (United States)

    Escribano, Jerónimo; Boucher, Olivier; Chevallier, Frédéric; Huneeus, Nicolás.

    2016-07-01

    The emission of mineral dust aerosols in arid and semiarid regions is a complex process whose representation in atmospheric models remains crude, due to insufficient knowledge about the aerosol lifting process itself, the lack of global data on soil characteristics, and the impossibility for the models to resolve the fine-scale variability in the wind field that drives some of the dust events. As a result, there are large uncertainties in the total emission flux of mineral dust, its natural variability at various timescales, and the possible contribution from anthropogenic land use changes. This work aims for estimating dust emissions and reduces their uncertainty over the Sahara desert and the Arabian Peninsula—the largest dust source region of the globe. We use a data assimilation approach to constrain dust emission fluxes at a monthly resolution for 18 subregions. The Moderate Resolution Imaging Spectroradiometer satellite-derived aerosol optical depth is assimilated in a regional configuration of a general circulation model coupled to an aerosol model. We describe this data assimilation system and apply it for 1 year, resulting in a total mineral dust emissions flux estimate of 2900 Tg yr-1 over the Sahara desert and the Arabian Peninsula for the year 2006. The analysis field of aerosol optical depth shows an improved fit relative to independent Aerosol Robotic Network measurements as compared to the model prior field.

  9. Coupling Mars' Dust and Water Cycles: Effects on Dust Lifting Vigor, Spatial Extent and Seasonality

    Science.gov (United States)

    Kahre, M. A.; Hollingsworth, J. L.; Haberle, R. M.; Montmessin, F.

    2012-01-01

    The dust cycle is an important component of Mars' current climate system. Airborne dust affects the radiative balance of the atmosphere, thus greatly influencing the thermal and dynamical state of the atmosphere. Dust raising events on Mars occur at spatial scales ranging from meters to planet-wide. Although the occurrence and season of large regional and global dust storms are highly variable from one year to the next, there are many features of the dust cycle that occur year after year. Generally, a low-level dust haze is maintained during northern spring and summer, while elevated levels of atmospheric dust occur during northern autumn and winter. During years without global-scale dust storms, two peaks in total dust loading were observed by MGS/TES: one peak occurred before northern winter solstice at Ls 200-240, and one peak occurred after northern winter solstice at L(sub s) 305-340. These maxima in dust loading are thought to be associated with transient eddy activity in the northern hemisphere, which has been observed to maximize pre- and post-solstice. Interactive dust cycle studies with Mars General Circulation Models (MGCMs) have included the lifting, transport, and sedimentation of radiatively active dust. Although the predicted global dust loadings from these simulations capture some aspects of the observed dust cycle, there are marked differences between the simulated and observed dust cycles. Most notably, the maximum dust loading is robustly predicted by models to occur near northern winter solstice and is due to dust lifting associated with down slope flows on the flanks of the Hellas basin. Thus far, models have had difficulty simulating the observed pre- and post- solstice peaks in dust loading. Interactive dust cycle studies typically have not included the formation of water ice clouds or their radiative effects. Water ice clouds can influence the dust cycle by scavenging dust from atmosphere and by interacting with solar and infrared radiation

  10. Biomonitoring spatial and temporal impact of atmospheric dust from a cement industry

    Energy Technology Data Exchange (ETDEWEB)

    Branquinho, Cristina [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande, Edificio C2, Piso 4, 1749-016 Lisbon (Portugal); Universidade Atlantica, Antiga Fabrica da Polvora de Barcarena, 2745-615 Barcarena (Portugal)], E-mail: cmbranquinho@fc.ul.pt; Gaio-Oliveira, Gisela; Augusto, Sofia; Pinho, Pedro; Maguas, Cristina; Correia, Otilia [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande, Edificio C2, Piso 4, 1749-016 Lisbon (Portugal)

    2008-01-15

    The objective of this work was to evaluate the spatial and temporal impact of dust-pollution in the vicinity of a cement industry, located in an area with dry climate. The spatial impact integrated over time was evaluated from the concentrations of Ca, Fe and Mg in in-situ Xanthoria parietina. The temporal pattern was assessed through one-month transplants of the lichen Ramalina canariensis. Four potential sources of atmospheric dust were evaluated: the limestone-quarry; the unpaved roads, the deposit area and the cement mill. Calcium concentration in lichens was considered the best cement-dust indicator. Different types of dust (clinker and grinded-limestone-dust) resulted in different time-patterns of Ca accumulation, which was also related with the different influence that wet and dry periods have in the lichen accumulation process. The dust pollution was found to be deposited locally and dependent on: the nature of dust particles and the volume and frequency of precipitation. - Biomonitoring Spatial and Temporal dust emissions in dry climates.

  11. Paracas dust storms: Sources, trajectories and associated meteorological conditions

    Science.gov (United States)

    Briceño-Zuluaga, F.; Castagna, A.; Rutllant, J. A.; Flores-Aqueveque, V.; Caquineau, S.; Sifeddine, A.; Velazco, F.; Gutierrez, D.; Cardich, J.

    2017-09-01

    Dust storms that develop along the Pisco-Ica desert in Southern Peru, locally known as ;Paracas; winds have ecological, health and economic repercussions. Here we identify dust sources through MODIS (Moderate Resolution Imaging Spectroradiometer) imagery and analyze HYSPLIT (Hybrid Single Particles Lagrangian Integrated Trajectory) model trajectories and dispersion patterns, along with concomitant synoptic-scale meteorological conditions from National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis (NCEP/NCAR). Additionally, surface pressure data from the hourly METeorological Aerodrome Report (METAR) at Arica (18.5°S, 70.3°W) and Pisco (13.7°S, 76.2°W) were used to calculate Alongshore (sea-level) Pressure Gradient (APG) anomalies during Paracas dust storms, their duration and associated wind-speeds and wind directions. This study provides a review on the occurrence and strength of the Paracas dust storms as reported in the Pisco airfield for five-year period and their correspondence with MODIS true-color imagery in terms of dust-emission source areas. Our results show that most of the particle fluxes moving into the Ica-Pisco desert area during Paracas wind events originate over the coastal zone, where strong winds forced by steep APGs develop as the axis of a deep mid-troposphere trough sets in along north-central Chile. Direct relationships between Paracas wind intensity, number of active dust-emission sources and APGs are also documented, although the scarcity of simultaneous METAR/MODIS data for clearly observed MODIS dust plumes prevents any significant statistical inference. Synoptic-scale meteorological composites from NCEP/NCAR reanalysis data show that Paracas wind events (steep APGs) are mostly associated with the strengthening of anticyclonic conditions in northern Chile, that can be attributed to cold air advection associated with the incoming trough. Compared to the MODIS images, HYSPLIT outputs were able

  12. Spatial Distributions of Multiple Dust Components in the PPN/PN Dust Shells

    CERN Document Server

    Ueta, T; Meixner, M; Dayal, A; Hora, J L; Fazio, G G; Deutsch, L K; Hoffmann, W F; Ueta, Toshiya; Speck, Angela K.; Meixner, Margaret; Dayal, Aditya; Hora, Joseph L.; Fazio, Giovanni G.; Deutsch, Lynne K.; Hoffmann, William F.

    2000-01-01

    We investigate spatial distributions of specific dust components in the circumstellar shells of a proto-planetary nebula candidate, HD 179821, and a planetary nebula, BD$+30^{\\circ}$3639, by means of spectral imaging. With high-resolution ground-based images and ISO spectra in the mid-infrared, we can derive ``dust feature only'' maps by subtracting synthesized continuum maps from the observed images at the feature wavelength. Such spatially detailed information will help to develop models for the evolution of dust grains around evolved stars.

  13. Satellite-based Dust Source Identification over North Africa: Diurnal Cycle, Meteorological Controls, and Interannual Variability

    Science.gov (United States)

    Schepanski, Kerstin; Tegen, Ina; Macke, Andreas

    2010-05-01

    Mineral dust aerosol emitted from arid and semi-arid areas impacts on the weather and climate system by affecting e.g. radiation fluxes and nutrient cycles. To estimate the effect of dust aerosol, detailed knowledge on the spatio-temporal distribution of active dust sources is necessary. For a better representation of dust-related processes in numerical models and climate change projections the knowledge on the natural variability of dust source activity has to be improved. As dust sources are mostly located over remote areas satellite observations are suitable for identifying active dust sources. The accuracy of dust source identification using such an indirect method is limited by the temporal resolution and the ambiguities of the retrieval. Here, a data set on the spatial (1°x1°) and temporal (3-hourly) distribution of dust source activations (DSA) over North Africa is compiled by analyzing 15-minute Meteosat Second Generation (MSG) infra-red (IR) dust index images since March 2006. The index is designed using radiances measured by the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) on-board MSG at 8.7 µm, 10.8 µm and 12.0 µm which are converted to brightness temperatures (BTs). To strengthen the dust signal, differences of BTs are used to compute RGB-composite images. This newly data set providing information on the diurnal cycle of dust emission has been used (1) to identify most active dust source areas, and (2) to investigate on the temporal distribution of DSAs. Over the Sahara Desert 65% of dust sources become active during 06-09 UTC pointing towards an important role of the break-down of the nocturnal low-level jet (LLJ) for dust mobilization besides other meteorological features like density currents, haboobs, and cyclones. Furthermore the role of the nocturnal LLJs for dust mobilization over the Sahara is investigated by weather observations and a regional modeling study. Four years of DSA observations indicate an interannual variability in

  14. Quantification of dust generating sources in gold and platinum mines

    CSIR Research Space (South Africa)

    Biffi, M

    2003-03-01

    Full Text Available dust generation rates linked to activities presumed to be hazardous in this respect. The aim of this study was to identify prominent dust sources that occur in hard rock mines and to characterise these by means of on-site measurement of dust generations...

  15. Polycyclic Aromatic Hydrocarbons in Residential Dust: Sources of Variability

    OpenAIRE

    Whitehead, Todd P; Metayer, Catherine; Petreas, Myrto; Does, Monique; Buffler, Patricia A.; Rappaport, Stephen M.

    2013-01-01

    Background: There is interest in using residential dust to estimate human exposure to environmental contaminants. Objectives: We aimed to characterize the sources of variability for polycyclic aromatic hydrocarbons (PAHs) in residential dust and provide guidance for investigators who plan to use residential dust to assess exposure to PAHs. Methods: We collected repeat dust samples from 293 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 thr...

  16. Effects of Spatial Resolution on the Simulated Dust Aerosol Lifecycle: Implications for Dust Event Magnitude and Timing in the NASA GEOS-5 AGCM

    Science.gov (United States)

    Nowottnick, E.; Colarco, Peter R.; daSilva, A.

    2011-01-01

    The NASA GEOS-5 atmospheric transport model simulates global aerosol distributions with an online aerosol module. GEOS-5 may be run at various horizontal spatial resolutions depending on the research application. For example, long integration climate simulations are typically run at 2 deg or 1 deg grid spacing, whereas aerosol reanalysis and forecasting applications may be performed at O.5 deg or 0.25 deg resolutions. In this study, we assess the implications of varying spatial resolution on the simulated aerosol fields, with a particular focus on dust. Dust emissions in GEOS-5 are calculated with one of two parameterizations, one based on the Goddard Chemistry, Aerosol, Radiation, and Transport (GO CART) model and another based on the Dust Entrainment and Deposition (DEAD) model. Emission fluxes are parameterized in terms of the surface wind speed, either the 10-m (GO CART) or friction (DEAD) wind speed. We consider how surface wind speeds and thus the dust emission rates are a function of the model spatial resolution. We find that spatial resolution has a significant effect on the magnitude of dust emissions, as higher resolution versions of the model have typically higher surface wind speeds. Utilizing space-borne observations from MISR, MODIS, and CALIOP, we find that simulated Aerosol Optical Thickness (AOT) distributions respond differently to spatial resolution over the African and Asian source regions, highlighting the need to regional dust emission tuning. When compared to ground-based observations from AERONET, we found improved timing of dust events with as spatial resolution was increased. In an attempt to improve the representation of the dust aerosol lifecycle at coarse resolutions, we found that incorporating the effects of sub-grid wind variability in a course resolution simulation led to improved agreement with observed AOT magnitudes, but did not impact the timing of simulated dust events.

  17. Spatial and temporal variation in magnetic properties of street dust in Lanzhou City, China

    Institute of Scientific and Technical Information of China (English)

    WANG Guan; XIA DunSheng; LIU XiuMing; CHEN FaHu; YU Ye; YANG LiPing; CHEN JianHui; ZHOU AiFeng

    2008-01-01

    Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in North-west China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain (PSD) magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentra-tions associated with heavy industry, concentrated residential development, and vehicular traffic sug-gest mixed contributions of magnetic material from both anthropogenic and natural sources. Xif and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic proper-ties in street dust, convenient and economical methods for monitoring street dust pollution.

  18. Dust-Metal Sources in an Urbanized Arid Zone: Implications for Health-Risk Assessments.

    Science.gov (United States)

    García-Rico, Leticia; Meza-Figueroa, Diana; Gandolfi, A Jay; Del Río-Salas, Rafael; Romero, Francisco M; Meza-Montenegro, Maria Mercedes

    2016-04-01

    The available information concerning metal pollution in different dust sources and the health effects in children remains limited in Mexico. This study focuses on Hermosillo, which is an urbanized area located in the Sonoran Desert in which soil resuspension and dust emission processes are common. The metal content of arsenic (As), chromium (Cr), manganese (Mn), and lead (Pb) were determined in three dust sources (playgrounds, roofs, and roads), each representing different exposure media (EM) for these elements. The metal levels in dust were found in the order of Mn > Cr > Pb > As with the highest metal content found in road dust. Despite the similar average metal distributions, principal component analysis shows a clear separation of the three EM with playground dust related to Cr and Mn and road dust to As and Pb. However, the geoaccumulation index results indicate that dust samples are uncontaminated to moderately polluted, except for Pb in road dust, which is considerably high. In addition, the enrichment factor suggests an anthropogenic origin for all of the studied metals except for Mn. In this context, the hazard index (HI) for noncarcinogenic risk is >1 in this population and thus represents a potential health risk. The spatial distribution for each metal on EM and the HI related to the marginality index could represent a more accurate decision-making tool in risk assessment studies.

  19. Monitoring Saharan dust from source to sink: from Iwik [Mauritania] to Statia [Caribbean

    Science.gov (United States)

    van Hateren, Hans; van der Does, Michelle; Friese, Carmen; Korte, Laura; Munday, Chris; Stuut, Jan-Berend

    2015-04-01

    The particle-size distribution and composition of mineral dust is often used as a tool to reconstruct palaeo-environmental conditions in the source(s) of the dust. In on-land (loess), lacustrine, and marine archives, the size of dust deposits is considered a proxy for paleo-wind intensity. However, next to wind strength, the particle size of aeolian deposits is also influenced by various other parameters such as source-to-sink distance, altitude at which the particles have been transported, and various environmental conditions in the sources of the dust. To verify if we can quantify a relationship between the size and composition of mineral dust particles and prevailing environmental conditions, we study "modern" dust. Within three ongoing projects, funded by the Dutch NWO, German DFG, and the ERC, we are studying dust collected on land in Mauritania (Iwik, in the Parc National de Banc d'Arguin, sampling on a monthly resolution) with an array of marine sediment-traps (five moorings at 12°N across the Atlantic Ocean with two sediment traps each between 23° and 57°W, sampling on a 2-weekly resolution) as well as automated mineral-dust collection at sea (on dust-collecting buoys at 12°N/38°W and 12°N/49°W, sampling on a 2-weekly resolution), and finally with a high-volume dust collector on St Eustatius (17°N/63°W, sampling on a 2-weekly resolution). Here we compare initial results of the particle-size distributions of the "minimally-disturbed" fraction of the on-land dust collectors with the terrigenous sediment fraction from the sediment traps, and discuss temporal and spatial trends.

  20. Global trends in visibility: implications for dust sources

    Directory of Open Access Journals (Sweden)

    N. M. Mahowald

    2007-06-01

    Full Text Available There is a large uncertainty in the relative roles of human land use, climate change and carbon dioxide fertilization in changing desert dust source strength over the past 100 years, and the overall sign of human impacts on dust is not known. We used visibility data from meteorological stations in dusty regions to assess the anthropogenic impact on long term trends in desert dust emissions. We did this by looking at time series of visibility derived variables and their correlations with precipitation, drought, winds, land use and grazing. Visibility data are available at thousands of stations globally from 1900 to the present, but we focused on 357 stations with more than 30 years of data in regions where mineral aerosols play a dominant role in visibility observations. We evaluated the 1974 to 2003 time period because most of these stations have reliable records only during this time. We first evaluated the visibility data against AERONET aerosol optical depth data, and found that only in dusty regions are the two moderately correlated. Correlation coefficients between visibility-derived variables and AERONET optical depths indicate a moderate correlation (0.47, consistent with capturing about 20% of the variability in optical depths. Two visibility-derived variables appear to compare the best with AERONET observations: the fraction of observations with visibility less than 5 km (VIS5 and the surface extinction (EXT. Regional trends show that in many dusty places, VIS5 and EXT are statistically significantly correlated with the Palmer drought severity index (based on precipitation and temperature or surface wind speeds, consistent with dust temporal variability being largely driven by meteorology. This is especially true for North African and Chinese dust sources, but less true in the Middle East, Australia or South America, where there are not consistent patterns in the correlations. Climate indices such as El Nino or the North Atlantic

  1. Global trends in visibility: Implications for dust sources

    Science.gov (United States)

    Mahowald, N.M.; Ballantine, J.A.; Feddema, J.; Ramankutty, N.

    2007-01-01

    There is a large uncertainty in the relative roles of human land use, climate change and carbon dioxide fertilization in changing desert dust source strength over the past 100 years, and the overall sign of human impacts on dust is not known. We used visibility data from meteorological stations in dusty regions to assess the anthropogenic impact on long term trends in desert dust emissions. We did this by looking at time series of visibility derived variables and their correlations with precipitation, drought, winds, land use and grazing. Visibility data are available at thousands of stations globally from 1900 to the present, but we focused on 357 stations with more than 30 years of data in regions where mineral aerosols play a dominant role in visibility observations. We evaluated the 1974 to 2003 time period because most of these stations have reliable records only during this time. We first evaluated the visibility data against AERONET aerosol optical depth data, and found that only in dusty regions are the two moderately correlated. Correlation coefficients between visibility-derived variables and AERONET optical depths indicate a moderate correlation (0.47), consistent with capturing about 20% of the variability in optical depths. Two visibility-derived variables appear to compare the best with AERONET observations: the fraction of observations with visibility less than 5 km (VIS5) and the surface extinction (EXT). Regional trends show that in many dusty places, VIS5 and EXT are statistically significantly correlated with the Palmer drought severity index (based on precipitation and temperature) or surface wind speeds, consistent with dust temporal variability being largely driven by meteorology. This is especially true for North African and Chinese dust sources, but less true in the Middle East, Australia or South America, where there are not consistent patterns in the correlations. Climate indices such as El Nino or the North Atlantic Oscillation are not

  2. Volumetric measurements of a spatially growing dust acoustic wave

    Science.gov (United States)

    Williams, Jeremiah D.

    2012-11-01

    In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.

  3. Volumetric measurements of a spatially growing dust acoustic wave

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Jeremiah D. [Physics Department, Wittenberg University, Springfield, Ohio 45504 (United States)

    2012-11-15

    In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.

  4. Dust Sources of Saturn's E Ring

    Science.gov (United States)

    Spahn, F.; Schmidt, J.; Albers, N.; Kempf, S.; Krivov, A. V.; Sremcevic, M.

    The recent detection of a dust plume at Enceladus' south pole sheds new light on the origin of the E ring of Saturn. The particles probably condense from gas vents escaping from a system of cracks covering the south pole that appears unusually hot in the Cassini infrared experiments. The main fraction of the E ring dust is created in these gas vents. Still, significant amounts of dust should originate from grains ejected by hypervelocity impacts of E ring particles (ERPs), or alternatively, of interplanetary dust grains (IDPs) on the Saturnian moons embedded in the E ring. We estimate the contributions of impactor -ejecta created dust at these various satellites in the ring, relative to the production rate of grains in the plume at Enceladus. Furthermore, we compare the amount of dust created by both projectile families - ERPs and IDPs - and predict that one can clearly discriminate between the ejecta raised by either projectile families in the data of the Cassini dust detector (CDA) collected at close flybys with the moons embedded in the E ring.

  5. Applying geochemical signatures of atmospheric dust to distinguish current mine emissions from legacy sources

    Science.gov (United States)

    Dong, Chenyin; Taylor, Mark Patrick

    2017-07-01

    Resolving the source of environmental contamination is the critical first step in remediation and exposure prevention. Australia's oldest silver-zinc-lead mine at Broken Hill (>130 years old) has generated a legacy of contamination and is associated with persistent elevated childhood blood lead (Pb) levels. However, the source of environmental Pb remains in dispute: current mine emissions; remobilized mine-legacy lead in soils and dusts; and natural lead from geological weathering of the gossan ore body. Multiple lines of evidence used to resolve this conundrum at Broken Hill include spatial and temporal variations in dust Pb concentrations and bioaccessibility, Pb isotopic compositions, particle morphology and mineralogy. Total dust Pb loading (mean 255 μg/m2/day) and its bioaccessibility (mean 75% of total Pb) is greatest adjacent to the active mining operations. Unweathered galena (PbS) found in contemporary dust deposits contrast markedly to Pb-bearing particles from mine-tailings and weathered gossan samples. Contemporary dust particles were more angular, had higher sulfur content and had little or no iron and manganese. Dust adjacent to the mine has Pb isotopic compositions (208Pb/207Pb: 2.3197; 206Pb/207Pb: 1.0406) that are a close match (99%) to the ore body with values slightly lower (94%) at the edge of the city. The weight of evidence supports the conclusion that contemporary dust Pb contamination in Broken Hill is sourced primarily from current mining activities and not from weathering or legacy sources.

  6. Potential Dust Emissions from Sources in the Southern Hemisphere.

    Science.gov (United States)

    Bhattachan, A.; D'Odorico, P.; Okin, G. S.

    2014-12-01

    The Southern Hemisphere currently exhibits low levels of atmospheric dust concentrations relative to the Northern Hemisphere. Recent research suggests that dust concentrations could, however, increase as a result of loss of vegetation cover in the Southern Kalahari and the Mallee. Disturbances resulting from grazing and agriculture are identified as such drivers of land use change in these regions. While studies on the importance of atmospheric dust in global-scale processes are abundant, little has been done to locate the potential dust sources in the Southern Hemisphere because potential new sources are by definition inactive and are undetected in satellite images. To this end, using a combination of laboratory experiments and field observations, we assess that the sediments collected from the dunefields in the Southern Kalahari and Mallee can emit substantial amount of dust, are rich in soluble iron and dust from these sources would reach the Southern Ocean. It is suggested that the supply of soluble iron through atmospheric dust deposition limits the productivity of the Southern Ocean. Thus intensification of land use can potentially make these regions an important source of iron given their proximity to the Southern Ocean. This iron-rich dust could stimulate ocean productivity in future as more areas are reactivated as a result of land-use and droughts.

  7. Polychlorinated biphenyls in the surrounding of an e-waste recycling facility in North-Rhine Westphalia: Levels in plants and dusts, spatial distribution, homologue pattern and source identification using the combination of plants and wind direction data.

    Science.gov (United States)

    Klees, Marcel; Hombrecher, Katja; Gladtke, Dieter

    2017-12-15

    During this study the occurrence of polychlorinated biphenyls (PCBs) in the surrounding of an e-waste recycling facility in North-Rhine Westphalia was analysed. PCB levels were analysed in curly kale, spruce needles, street dusts and dusts. Conspicuously high PCB concentrations in curly kale and spruce needles were found directly northwards of the industrial premises. Furthermore a concentration gradient originating from the industrial premises to the residential areas in direction southwest to northeast was evident. Homologue patterns of highly PCB contaminated dusts and street dusts were comparable to the homologue patterns of PCB in curly kale and spruce needles. This corroborates the suspicion that the activities at the e-waste recycling facility were responsible for the elevated PCB levels in curly kale and spruce needles. The utilization of multiple linear regression of wind direction data and analysed PCB concentrations in spruce needles proved that the e-waste recycling facility caused the PCB emissions to the surrounding. Additionally, this evaluation enabled the calculation of source specific accumulation constants for certain parts of the facility. Consequently the different facility parts contribute with different impacts to the PCB levels in bioindicators. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. On the Role of Flash Floods for Dust Emission over North Africa: Alluvial Sediments acting as Dust Source

    Science.gov (United States)

    Schepanski, K.; Klueser, L.; Tegen, I.

    2014-12-01

    Studies analyzing satellite dust products show that numerous dust sources are located in the foothills of arid and semi-arid mountain regions. There, alluvial sediments deposited on valley bottoms and flood plains are very susceptible to wind erosion and frequently serve as dust source. This study focuses on the spatio-temporal distribution of dust source activation events over the mountain foothills and flood plains over North Africa. Satellite dust retrievals with sub-daily resolution such as from Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and METOP A/B Infrared Atmospheric Sounding Interferometer (IASI) instruments are used to identify dust source regions. Identified dust source regions are then linked to soil properties and land type classification data sets. Information on the mineralogical composition of transported dust inferred from IASI observation are used (a) to investigate the impact of different source geomorphologies and thus different radiative properties of airborne dust particles, and (b) to estimate the contribution of dust uplift from alluvial sediments compared to dust emission from non-hydrological sources. Ultimately, this study contributes to the understanding of controlling mechanism on the interannual variability of dust source activation and will improve current dust emission modules coupled to atmosphere models.

  9. Non-monotonic spatial distribution of the interstellar dust in astrospheres: finite gyroradius effect

    Science.gov (United States)

    Katushkina, O. A.; Alexashov, D. B.; Izmodenov, V. V.; Gvaramadze, V. V.

    2017-02-01

    High-resolution mid-infrared observations of astrospheres show that many of them have filamentary (cirrus-like) structure. Using numerical models of dust dynamics in astrospheres, we suggest that their filamentary structure might be related to specific spatial distribution of the interstellar dust around the stars, caused by a gyrorotation of charged dust grains in the interstellar magnetic field. Our numerical model describes the dust dynamics in astrospheres under an influence of the Lorentz force and assumption of a constant dust charge. Calculations are performed for the dust grains with different sizes separately. It is shown that non-monotonic spatial dust distribution (viewed as filaments) appears for dust grains with the period of gyromotion comparable with the characteristic time-scale of the dust motion in the astrosphere. Numerical modelling demonstrates that the number of filaments depends on charge-to-mass ratio of dust.

  10. Characteristics and sources of 2002 super dust storm in Beijing

    Institute of Scientific and Technical Information of China (English)

    SUN Yele; ZHUANG Guoshun; YUAN Hui; ZHANG Xingying; GUO Jinghua

    2004-01-01

    On 20 March, 2002, a super dust storm attacked Beijing, which was stronger than any dust storm ever recorded. The concentration of total suspended particulates air quality standard. The concentrations of major crustal elements, such as Ca, Al, Fe, Na, Mg and Ti, were 30-58times higher than those in non-dust storm days. The concentrations of pollution elements, such as Zn, Cu, Pb, As, Cd and S, were also about several or even nearly ten times higher than those in normal days. The enrichment factors of Pb, As, Cd and S in PM2.5 were as high as 12.7, 29.6, 43.5,28.4, indicating that these pollutants came from the mixing of mineral aerosol with pollution aerosol emitted by pollution sources on the way of dust storm's long-range transport. The overlap of invaded air mass from dust with pollution air mass from Beijing local area was another reason for the enhancement of pollutants. During dust storm, fine particles (PM2.5) accounted for 30% of TSP and pollutants in PM2.5accounted for even as high as 45%-69% of TSP. The increase of pollutants after dust storm proved further that mineral aerosol, especially the fine particles from dust storm favored the transformation and accumulation of pollutants.It must be noted that Fe (Ⅱ) was detected again in this dust storm, which provided new evidence for the mechanism of coupling and feedback between iron and sulfur in the atmosphere and the ocean. The increase of both pollutants and nutrient, Fe(Ⅱ), during dust storm illuminated that dust storm is an important factor affecting the global environment change.

  11. The implications for dust emission modeling of spatial and vertical variations in horizontal dust flux and particle size in the Bodélé Depression, Northern Chad

    Science.gov (United States)

    Chappell, Adrian; Warren, Andrew; O'Donoghue, Alice; Robinson, Andrea; Thomas, Andrew; Bristow, Charlie

    2008-02-01

    The Bodélé Depression has been confirmed as the single largest source of atmospheric mineral dust on Earth. It is a distinctive source because of its large exposure of diatomite and the presence of mega-barchan dunes. Direct measurements of horizontal dust flux and particle size were made to investigate dust emission processes and for comparison with mechanisms of emission assumed in current dust models. More than 50 masts, with traps mounted on each, were located across and downwind of three barchans in 56 km2 study area of the eastern Bodélé. The size-distribution of surface material is bi-modal; there are many fine dust modes and a mixed mineralogy with a particle density three times smaller than quartz. Horizontal fluxes (up to 70 m above the playa) of particles, up to 1000 μm in diameter, are produced frequently from the accelerated flow over and around the barchans, even in below-threshold shear conditions on the diatomite playa. Our data on dust sizes do not conform to retrievals of dust size distributions from radiance measurements made in the same area. Dust emission models for the region may need to be revised to account for: saltators in the Bodélé, which are a mixture of quartz sand and diatomite flakes; the great spatial and vertical variation in the abundance, mass and density of dust and abraders; and the patterns of surface erodibility. All of these have important local effects on the vertical dust flux and its particle sizes.

  12. Dust as a collection media for contaminant source attribution.

    Science.gov (United States)

    Favela, Kristin Herrmann; Bohmann, Jonathan A; Williamson, William S

    2012-04-10

    Dust was investigated for its ability to retain source attribution profiles (SAPs) after chemical exposure. Three distinct sources of the organophosphate pesticide acephate were investigated as a proof-of-concept model. In addition, attribution profiles were created and tested using compounds related to chemical warfare agents (CWAs), specifically VX and G-series agents: O-ethyl methylphosphonothioate (EMPTA), N,N-diisopropylmethylamine (DIPMA), N,N-diisopropylethylamine (DIEA), diisopropylamine (DIPA), diethyl aniline (DEA), diethyl ethyl phosphonate (DEEP), trimethyl phosphite (TMP), dimethyl hydrogen phosphite (DMHP), diethyl hydrogen phosphite (DEHP), triethyl phosphate (TEP), ethyl methylphosphonate (EMPA), and diisopropyl methylphosphonate (DIMP). Dust was collected from a storage shed, aliquots deposited on carpet and loaded with distinct chemical profiles using an exposure chamber and aerosolizer. After a given period of time (1h, 24h, or 72 h), the dust was extracted and its SAP analyzed by gas chromatography-mass spectrometry (GC-MS) and/or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal components analysis (PCA) was used to determine the association of dust exposed to the same and different chemical sources. PCA results demonstrate that dust samples exposed to distinct chemical sources are clearly differentiated from one another across all collection times. Furthermore, dust aliquots exposed to the same source can be clearly associated with one another across all collection times. When the CWA-related compounds were subjected to elevated temperature (90°C) conditions, it was found that the signature was stable at the 1h and 24h collections. At 72 h and elevated temperature, larger deviations from the control were observed for some compounds. Elevated pH (10) affected the profile to a lesser degree than elevated temperature. Overall, dust is found to be an effective media for the in situ collection of source attribution profiles.

  13. Spatially resolved dust emission of extremely metal poor galaxies

    CERN Document Server

    Zhou, Luwenjia; Diaz-Santos, Taino; Armus, Lee; Helou, George; Stierwalt, Sabrina; Li, Aigen

    2016-01-01

    We present infrared (IR) spectral energy distributions (SEDs) of individual star-forming regions in four extremely metal poor (EMP) galaxies with metallicity Z around Zsun/10 as observed by the Herschel Space Observatory. With the good wavelength coverage of the SED, it is found that these EMP star-forming regions show distinct SED shapes as compared to those of grand design Spirals and higher metallicity dwarfs: they have on average much higher f70um/f160um ratios at a given f160um/f250um ratio; single modified black-body (MBB) fittings to the SED at \\lambda >= 100 um still reveal higher dust temperatures and lower emissivity indices compared to that of Spirals, while two MBB fittings to the full SED with a fixed emissivity index (beta = 2) show that even at 100 um about half of the emission comes from warm (50 K) dust, in contrast to the cold (~20 K) dust component. Our spatially resolved images further reveal that the far-IR colors including f70um/f160um, f160um/f250um and f250um/f350um are all related to ...

  14. Dust deposition: iron source or sink? A case study

    Directory of Open Access Journals (Sweden)

    Y. Ye

    2011-08-01

    Full Text Available A significant decrease of dissolved iron (DFe concentration has been observed after dust addition into mesocosms during the DUst experiment in a low Nutrient low chlorophyll Ecosystem (DUNE, carried out in the summer of 2008. Due to low biological productivity at the experiment site, biological consumption of iron can not explain the magnitude of DFe decrease. To understand processes regulating the observed DFe variation, we simulated the experiment using a one-dimensional model of the Fe biogeochemical cycle, coupled with a simple ecosystem model. Different size classes of particles and particle aggregation are taken into account to describe the particle dynamics. DFe concentration is regulated in the model by dissolution from dust particles and adsorption onto particle surfaces, biological uptake, and photochemical mobilisation of particulate iron.

    The model reproduces the observed DFe decrease after dust addition well. This is essentially explained by particle adsorption and particle aggregation that produces a high export within the first 24 h. The estimated particle adsorption rates range between the measured adsorption rates of soluble iron and those of colloidal iron, indicating both processes controlling the DFe removal during the experiment. A dissolution timescale of 3 days is used in the model, instead of an instantaneous dissolution, underlining the importance of dissolution kinetics on the short-term impact of dust deposition on seawater DFe.

    Sensitivity studies reveal that initial DFe concentration before dust addition was crucial for the net impact of dust addition on DFe during the DUNE experiment. Based on the balance between abiotic sinks and sources of DFe, a critical DFe concentration has been defined, above which dust deposition acts as a net sink of DFe, rather than a source. Taking into account the role of excess iron binding ligands and biotic processes, the critical DFe concentration might be applied to

  15. Spatially resolved dust emission of extremely metal-poor galaxies*

    Science.gov (United States)

    Zhou, Luwenjia; Shi, Yong; Diaz-Santos, Taino; Armus, Lee; Helou, George; Stierwalt, Sabrina; Li, Aigen

    2016-05-01

    We present infrared (IR) spectral energy distributions (SEDs) of individual star-forming regions in four extremely metal-poor (EMP) galaxies with metallicity Z ≲ Z⊙/10 as observed by the Herschel Space Observatory. With the good wavelength coverage of the SED, it is found that these EMP star-forming regions show distinct SED shapes as compared to those of grand design Spirals and higher metallicity dwarfs: they have on average much higher f70μm/f160 μm ratios at a given f160 μm/f250 μm ratio; single modified blackbody (MBB) fittings to the SED at λ ≥ 100 μm still reveal higher dust temperatures and lower emissivity indices compared to that of Spirals, while two MBB fittings to the full SED with a fixed emissivity index (β = 2) show that even at 100 μm, about half of the emission comes from warm (50 K) dust, in contrast to the cold (˜20 K) dust component. Our spatially resolved images furthermore reveal that the far-IR colours including f70 μm/f160 μm, f160 μm/f250 μm and f250 μm/f350 μm are all related to the surface densities of young stars as traced by far-UV, 24 μm and star formation rates (SFRs), but not to the stellar mass surface densities. This suggests that the dust emitting at wavelengths from 70 to 350 μm is primarily heated by radiation from young stars.

  16. Tracing geogenic and anthropogenic sources in urban dusts: Insights from lead isotopes

    Science.gov (United States)

    Del Rio-Salas, R.; Ruiz, J.; De la O-Villanueva, M.; Valencia-Moreno, M.; Moreno-Rodríguez, V.; Gómez-Alvarez, A.; Grijalva, T.; Mendivil, H.; Paz-Moreno, F.; Meza-Figueroa, D.

    2012-12-01

    Tracing the source of metals in the environment is critical to understanding their pollution level and fate. Geologic materials are an important source of airborne particulate matter, but the contribution of contaminated soil to concentrations of Pb in airborne dust is not yet widely documented. To examine the potential significance of this mechanism, surface soil samples were collected, as well as wind-transported dust trapped at 1 and 2 m height at seven different locations including residential, industrial, high-traffic and rural sites. Samples of dust deposited on roofs from 24 schools were also obtained and analyzed for Pb isotope ratios. Spatial distribution of Pb of airborne and sedimented dust suggests a process dominated by re-suspension/sedimentation, which was controlled by erosion, traffic and topography of the urban area. Anthropogenic lead input in the city grades outward the urban zone toward geogenic values. Our results shows that Pb-isotopic signatures of leaded gasoline are imprinted in dust sedimented on roofs. Considering that leaded-gasoline has not been in use in Mexico since two decades ago, this signature shows not only a Pb-legacy in soil, but also a re-suspension process affecting air column below 3 m in height. The combination of the 207Pb/206Pb data of the surrounding rocks and urban dust, reveal three well-defined zones with remarkable anthropogenic influence, which correspond to the oldest urban sectors. This work highlights the importance of spatial characterization of metals in particles suspended below a height of 3 m of the airborne column, a fact that should be considered to identify exposure paths to humans and the potential risks. Lead isotope signatures allowed the identification of geogenic and anthropogenic emission sources for dust, a matter that deserves consideration in the efforts to control airborne metal emissions.

  17. Surface Properties Associated With Dust Storm Plume's Point-Source Locations In The Border Region Of The US And Mexico

    Science.gov (United States)

    Bleiweiss, M. P.; DuBois, D. W.; Flores, M. I.

    2013-12-01

    Dust storms in the border region of the Southwest US and Northern Mexico are a serious problem for air quality (PM10 exceedances), health (Valley Fever is pandemic in the region) and transportation (road closures and deadly traffic accidents). In order to better understand the phenomena, we are attempting to identify critical characteristics of dust storm sources so that, possibly, one can perform more accurate predictions of events and, thus, mitigate some of the deleterious effects. Besides the emission mechanisms for dust storm production that are tied to atmospheric dynamics, one must know those locations whose source characteristics can be tied to dust production and, therefore, identify locations where a dust storm is eminent under favorable atmospheric dynamics. During the past 13 years, we have observed, on satellite imagery, more than 500 dust events in the region and are in the process of identifying the source regions for the dust plumes that make up an event. Where satellite imagery exists with high spatial resolution (less than or equal to 250m), dust 'plumes' appear to be made up of individual and merged plumes that are emitted from a 'point source' (smaller than the resolution of the imagery). In particular, we have observed events from the ASTER sensor whose spatial resolution is 15m as well as Landsat whose spatial resolution is 30m. Tying these source locations to surface properties such as NDVI, albedo, and soil properties (percent sand, silt, clay, and gravel; soil moisture; etc.) will identify regions with enhanced capability to produce a dust storm. This, along with atmospheric dynamics, will allow the forecast of dust events. The analysis of 10 events from the period 2004-2013, for which we have identified 1124 individual plumes, will be presented.

  18. Polycyclic Aromatic Hydrocarbons in Residential Dust: Sources of Variability

    Science.gov (United States)

    Metayer, Catherine; Petreas, Myrto; Does, Monique; Buffler, Patricia A.; Rappaport, Stephen M.

    2013-01-01

    Background: There is interest in using residential dust to estimate human exposure to environmental contaminants. Objectives: We aimed to characterize the sources of variability for polycyclic aromatic hydrocarbons (PAHs) in residential dust and provide guidance for investigators who plan to use residential dust to assess exposure to PAHs. Methods: We collected repeat dust samples from 293 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 through 2007 and during 2010) using household vacuum cleaners, and measured 12 PAHs using gas chromatography–mass spectrometry. We used a random- and a mixed-effects model for each PAH to apportion observed variance into four components and to identify sources of variability. Results: Median concentrations for individual PAHs ranged from 10 to 190 ng/g of dust. For each PAH, total variance was apportioned into regional variability (1–9%), intraregional between-household variability (24–48%), within-household variability over time (41–57%), and within-sample analytical variability (2–33%). Regional differences in PAH dust levels were associated with estimated ambient air concentrations of PAH. Intraregional differences between households were associated with the residential construction date and the smoking habits of residents. For some PAHs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Within-household differences between sampling rounds were largest when the interval between dust sample collections was at least 6 years in duration. Conclusions: Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PAH exposures in studies of health effects. PMID:23461863

  19. Spatio-temporal distribution of Saharan dust source activations inferred from 15-minute MSG-SEVIRI observations and its links to meteorological processes (Invited)

    Science.gov (United States)

    Schepanski, K.; Tegen, I.

    2009-12-01

    Mineral dust aerosol emitted from arid and semi-arid areas impacts on the weather and climate system by affecting e.g. radiation fluxes and nutrient cycles. The emission of dust particles depend strongly on surface wind velocity and turbulent fluxes as well as on surface characteristics like surface texture and vegetation cover. To estimate the effect of dust aerosol, detailed knowledge on the spatio-temporal distribution of active dust sources is necessary. As dust sources are mostly located over remote areas satellite observations are suitable for localizing active dust sources. Thereby the accuracy of determining dust sources from such an indirect method is limited by the temporal resolution and the ambiguities of the retrieval. A 1°x1° map on the spatial and temporal (3-hourly) distribution of dust source activations (DSA) over North Africa is compiled starting in March 2006. For dust source identification 15-minute Meteosat Second Generation (MSG) infra-red (IR) dust index images are used based on brightness temperature measurements by the Spinning enhanced Visible and Infra-Red Imager (SEVIRI) at 8.7 µm, 10.8 µm and 12.0 µm. This data set has been used (1) to identify most active dust source areas, and (2) to investigate on the temporal distribution of occurring dust source activations. Over the Sahara Desert 65% of dust sources becomes active during 06-09 UTC pointing towards an important role of the break-down of the nocturnal low-level jet (LLJ) for dust mobilization besides other meteorological features like density currents, haboobs, and cyclones. Furthermore the role of the nocturnal LLJ for dust mobilization over the Sahara is investigated by weather observations and a modelling study. DSA observations of the last 3.5 years indicate an interannual variability in frequencies of local dust source activations. The causes of this variability will be analyzed with respect to corresponding atmospheric conditions.

  20. Metal contamination in campus dust of Xi'an, China: A study based on multivariate statistics and spatial distribution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hao [School of Tourism and Environment, Shaanxi Normal University, Xi' an 710062 (China); Lu, Xinwei, E-mail: luxinwei@snnu.edu.cn [School of Tourism and Environment, Shaanxi Normal University, Xi' an 710062 (China); Li, Loretta Y., E-mail: lli@civil.ubc.ca [Department of Civil Engineering, University of British Columbia, Vancouver V6T 1Z4 (Canada); Gao, Tianning; Chang, Yuyu [School of Tourism and Environment, Shaanxi Normal University, Xi' an 710062 (China)

    2014-06-01

    The concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V and Zn in campus dust from kindergartens, elementary schools, middle schools and universities of Xi'an, China were determined by X-ray fluorescence spectrometry. Correlation coefficient analysis, principal component analysis (PCA) and cluster analysis (CA) were used to analyze the data and to identify possible sources of these metals in the dust. The spatial distributions of metals in urban dust of Xi'an were analyzed based on the metal concentrations in campus dusts using the geostatistics method. The results indicate that dust samples from campuses have elevated metal concentrations, especially for Pb, Zn, Co, Cu, Cr and Ba, with the mean values of 7.1, 5.6, 3.7, 2.9, 2.5 and 1.9 times the background values for Shaanxi soil, respectively. The enrichment factor results indicate that Mn, Ni, V, As and Ba in the campus dust were deficiently to minimally enriched, mainly affected by nature and partly by anthropogenic sources, while Co, Cr, Cu, Pb and Zn in the campus dust and especially Pb and Zn were mostly affected by human activities. As and Cu, Mn and Ni, Ba and V, and Pb and Zn had similar distribution patterns. The southwest high-tech industrial area and south commercial and residential areas have relatively high levels of most metals. Three main sources were identified based on correlation coefficient analysis, PCA, CA, as well as spatial distribution characteristics. As, Ni, Cu, Mn, Pb, Zn and Cr have mixed sources — nature, traffic, as well as fossil fuel combustion and weathering of materials. Ba and V are mainly derived from nature, but partly also from industrial emissions, as well as construction sources, while Co principally originates from construction. - Highlights: • Metal content in dust from schools was determined by XRF. • Spatial distribution of metals in urban dust was focused on campus samples. • Multivariate statistic and spatial distribution were used to identify metal

  1. Disposal Unit Source Term (DUST) data input guide

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, T.M. [Brookhaven National Lab., Upton, NY (United States)

    1993-05-01

    Performance assessment of a low-level waste (LLW) disposal facility begins with an estimation of the rate at which radionuclides migrate out of the facility (i.e., the source term). The focus of this work is to develop a methodology for calculating the source term. In general, the source term is influenced by the radionuclide inventory, the wasteforms and containers used to dispose of the inventory, and the physical processes that lead to release from the facility (fluid flow, container degradation, wasteform leaching, and radionuclide transport). The computer code DUST (Disposal Unit Source Term) has been developed to model these processes. This document presents the models used to calculate release from a disposal facility, verification of the model, and instructions on the use of the DUST code. In addition to DUST, a preprocessor, DUSTIN, which helps the code user create input decks for DUST and a post-processor, GRAFXT, which takes selected output files and plots them on the computer terminal have been written. Use of these codes is also described.

  2. Temperate grasslands as a dust source: Knowledge, uncertainties, and challenges

    Science.gov (United States)

    Shinoda, M.; Gillies, J. A.; Mikami, M.; Shao, Y.

    2011-12-01

    Temperate grasslands are sensitive to climate change and are significant, or potentially significant, dust sources. Temperate grassland aeolian processes are unique in that the vegetation growth-decay cycle and weathering process due to extreme temperature changes profoundly affect the occurrence and intensity of wind erosion and dust emission. Human activities, such as animal husbandry or cultivation, also may result in land degradation and enhanced wind erosion. So far, little systematic research on temperate grassland wind erosion has been done, but this issue deserves particular attention. In this review paper, we summarize the understanding of temperate grassland wind-erosion processes and identify the uncertainties and research needs. The needs include (1) a deeper understanding of the aerodynamic and physical controls of grassland vegetation on wind erosion and dust emission processes, (2) scaling known relationships upwards to model the regional scale, (3) quantifying critical parameters affecting dust emissions (i.e., surface and aerodynamic roughness) via remote-sensing techniques, and (4) integrated wind-erosion modeling that incorporates grassland aeolian database and vegetation modeling of both seasonal growth and decay plus the impacts of grazing and cultivation. We also outline the research being carried out by Japanese scientists in collaboration with colleagues at Mongolian, American, and German research institutes in developing a temperate grassland wind-erosion modeling system, which can be used as a pre-warning system of severe dust storms and as a tool for strategic management of temperate grasslands.

  3. Arabian Red Sea coastal soils as potential mineral dust sources

    KAUST Repository

    Prakash, P. Jish

    2016-09-26

    Both Moderate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) satellite observations suggest that the narrow heterogeneous Red Sea coastal region is a frequent source of airborne dust that, because of its proximity, directly affects the Red Sea and coastal urban centers. The potential of soils to be suspended as airborne mineral dust depends largely on soil texture, moisture content and particle size distributions. Airborne dust inevitably carries the mineralogical and chemical signature of a parent soil. The existing soil databases are too coarse to resolve the small but important coastal region. The purpose of this study is to better characterize the mineralogical, chemical and physical properties of soils from the Arabian Red Sea coastal plain, which in turn will help to improve assessment of dust effects on the Red Sea, land environmental systems and urban centers. Thirteen surface soils from the hot-spot areas of windblown mineral dust along the Red Sea coastal plain were sampled for analysis. Analytical methods included optical microscopy, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), ion chromatography (IC), scanning electron microscopy (SEM) and laser particle size analysis (LPSA). We found that the Red Sea coastal soils contain major components of quartz and feldspar, as well as lesser but variable amounts of amphibole, pyroxene, carbonate, clays and micas, with traces of gypsum, halite, chlorite, epidote and oxides. The range of minerals in the soil samples was ascribed to the variety of igneous and metamorphic provenance rocks of the Arabian Shield forming the escarpment to the east of the Red Sea coastal plain. The analysis revealed that the samples contain compounds of nitrogen, phosphorus and iron that are essential nutrients to marine life. The analytical results from this study will provide a valuable input into dust emission models used in climate

  4. Polybrominated Diphenyl Ethers in Residential Dust: Sources of Variability

    Science.gov (United States)

    Whitehead, Todd P.; Brown, F. Reber; Metayer, Catherine; Park, June-Soo; Does, Monique; Petreas, Myrto X.; Buffler, Patricia A.; Rappaport, Stephen M.

    2013-01-01

    We characterized the sources of variability for polybrominated diphenyl ethers (PBDEs) in residential dust and provided guidance for investigators who plan to use residential dust to assess exposure to PBDEs. We collected repeat dust samples from 292 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001–2007 and during 2010) using household vacuum cleaners and measured 22 PBDEs using high resolution gas chromatography-high resolution mass spectrometry. Median concentrations for individual PBDEs ranged from <0.1–2,500 ng per g of dust. For each of eight representative PBDEs, we used a random-effects model to apportion total variance into regional variability (0–11%), intra-regional between-household variability (17–50%), within-household variability over time (38–74%), and within-sample variability (0–23%) and we used a mixed-effects model to identify determinants of PBDE levels. Regional differences in PBDE dust levels were associated with residential characteristics that differed by region, including the presence of furniture with exposed or crumbling foam and the recent installation of carpets in the residence. Intra-regional differences between households were associated with neighborhood urban density, racial and ethnic characteristics, and to a lesser extent, income. For some PBDEs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PBDE exposures in studies of children’s health (e.g., the Northern California Childhood Leukemia Study). PMID:23628589

  5. Arabian Red Sea coastal soils as potential mineral dust sources

    Science.gov (United States)

    Jish Prakash, P.; Stenchikov, Georgiy; Tao, Weichun; Yapici, Tahir; Warsama, Bashir; Engelbrecht, Johann P.

    2016-09-01

    Both Moderate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) satellite observations suggest that the narrow heterogeneous Red Sea coastal region is a frequent source of airborne dust that, because of its proximity, directly affects the Red Sea and coastal urban centers. The potential of soils to be suspended as airborne mineral dust depends largely on soil texture, moisture content and particle size distributions. Airborne dust inevitably carries the mineralogical and chemical signature of a parent soil. The existing soil databases are too coarse to resolve the small but important coastal region. The purpose of this study is to better characterize the mineralogical, chemical and physical properties of soils from the Arabian Red Sea coastal plain, which in turn will help to improve assessment of dust effects on the Red Sea, land environmental systems and urban centers. Thirteen surface soils from the hot-spot areas of windblown mineral dust along the Red Sea coastal plain were sampled for analysis. Analytical methods included optical microscopy, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), ion chromatography (IC), scanning electron microscopy (SEM) and laser particle size analysis (LPSA). We found that the Red Sea coastal soils contain major components of quartz and feldspar, as well as lesser but variable amounts of amphibole, pyroxene, carbonate, clays and micas, with traces of gypsum, halite, chlorite, epidote and oxides. The range of minerals in the soil samples was ascribed to the variety of igneous and metamorphic provenance rocks of the Arabian Shield forming the escarpment to the east of the Red Sea coastal plain. The analysis revealed that the samples contain compounds of nitrogen, phosphorus and iron that are essential nutrients to marine life. The analytical results from this study will provide a valuable input into dust emission models used in climate

  6. Dry lake beds as sources of dust in Australia during the Late Quaternary: A volumetric approach based on lake bed and deflated dune volumes

    Science.gov (United States)

    Farebrother, Will; Hesse, Paul P.; Chang, Hsing-Chung; Jones, Claudia

    2017-04-01

    Dust affects Earth's climate, ecology and economies across a broad range of scales, both temporally and spatially, and is an integral part of the earth's climate system. Previous studies have highlighted the importance of inland lake beds to dust emissions both locally and globally. This study aims to explore the relative volumetric importance of ephemeral lakes that emit dust to the Australian southeastern dust path over the last glacial cycle. SRTM DEMs and GIS analyses of long-term (up to 80 ka) lake-bed deflation volumes and deposition of sand-sized sediment onto downwind source bordering dunes were used to derive estimates of transported dust mass. A strong power relationship was found between lake area and the mass of deflated lake bed sediments. Total dust masses for the largest 53 lakes in southeastern Australia were derived using the relationship between lake area and dust mass and used to determine an upper value for total dust mass deflated from lake beds in southeastern Australia. Ephemeral lake-derived dust was found to represent at most 13% of the dust derived from southeastern Australia deposited in the southern Pacific over the last 80 ka or 22% over the last 40 ka. Lake Eyre (the largest lake) has contributed at most 3% of the Australian southeast dust plume. These results imply that there are significant additional sources of dust in Australia over these timescales, such as floodplains or dunefields, and that modelling must allow for diverse climatic and geomorphic controls on dust production.

  7. THE DUST BUDGET OF THE SMALL MAGELLANIC CLOUD: ARE ASYMPTOTIC GIANT BRANCH STARS THE PRIMARY DUST SOURCE AT LOW METALLICITY?

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, M. L.; Gordon, K. D.; Meixner, M.; Sargent, B. A. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Srinivasan, S. [UPMC-CNRS UMR7095, Institut d' Astrophysique de Paris, F-75014 Paris (France); Riebel, D. [Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); McDonald, I. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Van Loon, J. Th. [Astrophysics Group, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG (United Kingdom); Clayton, G. C. [Department of Physics and Astronomy, Louisiana State University, 233-A Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States); Sloan, G. C., E-mail: mboyer@stsci.edu [Astronomy Department, Cornell University, Ithaca, NY 14853-6801 (United States)

    2012-03-20

    We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud, using the 8 {mu}m excess emission as a proxy for the dust-production rate (DPR). We find that asymptotic giant branch (AGB) and red supergiant (RSG) stars produce (8.6-9.5) Multiplication-Sign 10{sup -7} M{sub Sun} yr{sup -1} of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%-50% uncertainty in individual DPRs). RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called extreme AGB stars) account for 87%-89% of the total dust input from cool evolved stars. We also estimate the dust input from hot stars and supernovae (SNe), and find that if SNe produce 10{sup -3} M{sub Sun} of dust each, then the total SN dust input and AGB input are roughly equivalent. We consider several scenarios of SN dust production and destruction and find that the interstellar medium (ISM) dust can be accounted for solely by stellar sources if all SNe produce dust in the quantities seen around the dustiest examples and if most SNe explode in dense regions where much of the ISM dust is shielded from the shocks. We find that AGB stars contribute only 2.1% of the ISM dust. Without a net positive contribution from SNe to the dust budget, this suggests that dust must grow in the ISM or be formed by another unknown mechanism.

  8. Spatial distribution of mineral dust single scattering albedo based on DREAM model

    Science.gov (United States)

    Kuzmanoski, Maja; Ničković, Slobodan; Ilić, Luka

    2016-04-01

    Mineral dust comprises a significant part of global aerosol burden. There is a large uncertainty in estimating role of dust in Earth's climate system, partly due to poor characterization of its optical properties. Single scattering albedo is one of key optical properties determining radiative effects of dust particles. While it depends on dust particle sizes, it is also strongly influenced by dust mineral composition, particularly the content of light-absorbing iron oxides and the mixing state (external or internal). However, an assumption of uniform dust composition is typically used in models. To better represent single scattering albedo in dust atmospheric models, required to increase accuracy of dust radiative effect estimates, it is necessary to include information on particle mineral content. In this study, we present the spatial distribution of dust single scattering albedo based on the Dust Regional Atmospheric Model (DREAM) with incorporated particle mineral composition. The domain of the model covers Northern Africa, Middle East and the European continent, with horizontal resolution set to 1/5°. It uses eight particle size bins within the 0.1-10 μm radius range. Focusing on dust episode of June 2010, we analyze dust single scattering albedo spatial distribution over the model domain, based on particle sizes and mineral composition from model output; we discuss changes in this optical property after long-range transport. Furthermore, we examine how the AERONET-derived aerosol properties respond to dust mineralogy. Finally we use AERONET data to evaluate model-based single scattering albedo. Acknowledgement We would like to thank the AERONET network and the principal investigators, as well as their staff, for establishing and maintaining the AERONET sites used in this work.

  9. THE SPATIAL DISTRIBUTION OF DUST AND STELLAR EMISSION OF THE MAGELLANIC CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Skibba, Ramin A.; Engelbracht, Charles W.; Misselt, Karl; Montiel, Edward [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Aniano, Gonzalo [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544 (United States); Babler, Brian [Department of Astronomy, 475 North Charter St., University of Wisconsin, Madison, WI 53706 (United States); Bernard, Jean-Philippe [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Bot, Caroline [Universite de Strasbourg, Observatoire Astronomique de Strasbourg, F-67000 Strasbourg (France); Carlson, Lynn Redding; Israel, Frank [Sterrewacht Leiden, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Galametz, Maud [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Galliano, Frederic; Hony, Sacha; Lebouteiller, Vianney; Madden, Suzanne; Okumura, Koryo; Panuzzo, Pasquale [AIM, CEA/Saclay, L' Orme des Merisiers, 91191 Gif-sur-Yvette (France); Gordon, Karl; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Li, Aigen, E-mail: rskibba@ucsd.edu [314 Physics Building, Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); and others

    2012-12-10

    We study the emission by dust and stars in the Large and Small Magellanic Clouds, a pair of low-metallicity nearby galaxies, as traced by their spatially resolved spectral energy distributions. This project combines Herschel Space Observatory PACS and SPIRE far-infrared photometry with other data at infrared and optical wavelengths (the data were obtained as part of the HERschel Inventory of The Agents of Galaxy Evolution survey; PI: M. Meixner). We build maps of dust, stellar luminosity, and mass of both Magellanic Clouds, and analyze the spatial distribution of dust/stellar luminosity and mass ratios. These ratios vary considerably throughout the galaxies, generally between the range 0.01 {<=} L{sub dust}/L{sub *} {<=} 0.6 and 10{sup -4} {<=} M{sub dust}/M{sub *} {<=} 4 Multiplication-Sign 10{sup -3}. We observe that the dust/stellar ratios depend on the interstellar medium environment, such as the distance from currently or previously star-forming regions, and on the intensity of the interstellar radiation field. In addition, we construct star formation rate (SFR) maps, and find that the SFR is correlated with the dust/stellar luminosity and dust temperature in both galaxies, demonstrating the relation between star formation, dust emission, and heating, though these correlations exhibit substantial scatter.

  10. Dust sources and atmospheric circulation in concert controlling Saharan dust emission and transport towards the Western Mediterranean Basin

    Science.gov (United States)

    Schepanski, Kerstin; Mallet, Marc; Heinold, Bernd; Ulrich, Max

    2017-04-01

    Dust transported from north African source regions towards Europe is a ubiquitous phenomenon in the Mediterranean region, a geographic region that is in part densely populated. Besides its impacts on the atmospheric radiation budget, dust suspended in the atmosphere results in reduced air quality, which is generally sensed as a reduction in quality of life. Furthermore, the exposure to dust aerosols enhances the prevalence of respiratory diseases, which reduces the general human wellbeing, and ultimately results in an increased loss of working hours due to illness and hospitalization rates. Characteristics of the atmospheric dust life cycle that determine dust transport will be presented with focus on the ChArMEx special observation period in June and July 2013 using the atmosphere-dust model COSMO-MUSCAT (COSMO: Consortium for Small-scale MOdeling; MUSCAT: MUltiScale Chemistry Aerosol Transport Model). Modes of atmospheric circulation were identified from empirical orthogonal function (EOF) analysis of the geopotential height at 850 hPa for summer 2013 and compared to EOFs calculated from 1979-2015 ERA-Interim reanalysis. Generally, two different phases were identified. They are related to the eastward propagation of the subtropical ridge into the Mediterranean basin, the position of the Saharan heat low, and the predominant Iberian heat low. The relation of these centres of action illustrates a dipole pattern for enhanced (reduced) dust emission fluxes, stronger (weaker) meridional dust transport, and consequent increase (decrease) atmospheric dust concentrations and deposition fluxes. In concert, the results from this study aim at illustrating the relevance of knowing the dust source locations in concert with the atmospheric circulation. Ultimately, this study addresses the question of what is finally transported towards the Mediterranean basin and Europe from which source regions - and fostered by which atmospheric circulation pattern. Outcomes from this study

  11. PROPERTIES AND SPATIAL DISTRIBUTION OF DUST EMISSION IN THE CRAB NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    Temim, Tea; Sonneborn, George; Dwek, Eli; Arendt, Richard G. [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gehrz, Robert D. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Slane, Patrick [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Roellig, Thomas L., E-mail: tea.temim@nasa.gov [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000 (United States)

    2012-07-01

    Recent infrared (IR) observations of freshly formed dust in supernova remnants have yielded significantly lower dust masses than predicted by theoretical models and measured from high-redshift observations. The Crab Nebula's pulsar wind is thought to be sweeping up freshly formed supernova (SN) dust along with the ejected gas. The evidence for this dust was found in the form of an IR excess in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially resolved emission spectra of dust in the Crab Nebula acquired with the Infrared Spectrograph on board the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from S, Si, Ne, Ar, O, Fe, and Ni. We derived a synchrotron spectral map from the 3.6 and 4.5 {mu}m images, and subtracted this contribution from our data to produce a map of the residual continuum emission from dust. The dust emission appears to be concentrated along the ejecta filaments and is well described by an amorphous carbon or silicate grain compositions. We find a dust temperature of 55 {+-} 4 K for silicates and 60 {+-} 7 K for carbon grains. The total estimated dust mass is (1.2-12) Multiplication-Sign 10{sup -3} M{sub Sun }, well below the theoretical dust yield predicted for a core-collapse supernova. Our grain heating model implies that the dust grain radii are relatively small, unlike what is expected for dust grains formed in a Type IIP SN.

  12. Temporal and spatial variability of Icelandic dust emissions and atmospheric transport

    Directory of Open Access Journals (Sweden)

    C. D. Groot Zwaaftink

    2017-09-01

    Full Text Available Icelandic dust sources are known to be highly active, yet there exist few model simulations of Icelandic dust that could be used to assess its impacts on the environment. We here present estimates of dust emission and transport in Iceland over 27 years (1990–2016 based on FLEXDUST and FLEXPART simulations and meteorological re-analysis data. Simulations for the year 2012 based on high-resolution operational meteorological analyses are used for model evaluation based on PM2. 5 and PM10 observations in Iceland. For stations in Reykjavik, we find that the spring period is well predicted by the model, while dust events in late fall and early winter are overpredicted. Six years of dust concentrations observed at Stórhöfði (Heimaey show that the model predicts concentrations of the same order of magnitude as observations and timing of modelled and observed dust peaks agrees well. Average annual dust emission is 4.3 ± 0.8 Tg during the 27 years of simulation. Fifty percent of all dust from Iceland is on average emitted in just 25 days of the year, demonstrating the importance of a few strong events for annual total dust emissions. Annual dust emission as well as transport patterns correlate only weakly to the North Atlantic Oscillation. Deposition amounts in remote regions (Svalbard and Greenland vary from year to year. Only limited dust amounts reach the upper Greenland Ice Sheet, but considerable dust amounts are deposited on Icelandic glaciers and can impact melt rates there. Approximately 34 % of the annual dust emission is deposited in Iceland itself. Most dust (58 %, however, is deposited in the ocean and may strongly influence marine ecosystems.

  13. Temporal and spatial variability of Icelandic dust emissions and atmospheric transport

    Science.gov (United States)

    Groot Zwaaftink, Christine D.; Arnalds, Ólafur; Dagsson-Waldhauserova, Pavla; Eckhardt, Sabine; Prospero, Joseph M.; Stohl, Andreas

    2017-09-01

    Icelandic dust sources are known to be highly active, yet there exist few model simulations of Icelandic dust that could be used to assess its impacts on the environment. We here present estimates of dust emission and transport in Iceland over 27 years (1990-2016) based on FLEXDUST and FLEXPART simulations and meteorological re-analysis data. Simulations for the year 2012 based on high-resolution operational meteorological analyses are used for model evaluation based on PM2. 5 and PM10 observations in Iceland. For stations in Reykjavik, we find that the spring period is well predicted by the model, while dust events in late fall and early winter are overpredicted. Six years of dust concentrations observed at Stórhöfði (Heimaey) show that the model predicts concentrations of the same order of magnitude as observations and timing of modelled and observed dust peaks agrees well. Average annual dust emission is 4.3 ± 0.8 Tg during the 27 years of simulation. Fifty percent of all dust from Iceland is on average emitted in just 25 days of the year, demonstrating the importance of a few strong events for annual total dust emissions. Annual dust emission as well as transport patterns correlate only weakly to the North Atlantic Oscillation. Deposition amounts in remote regions (Svalbard and Greenland) vary from year to year. Only limited dust amounts reach the upper Greenland Ice Sheet, but considerable dust amounts are deposited on Icelandic glaciers and can impact melt rates there. Approximately 34 % of the annual dust emission is deposited in Iceland itself. Most dust (58 %), however, is deposited in the ocean and may strongly influence marine ecosystems.

  14. Dust deposition and ambient PM10 concentration in northwest China: spatial and temporal variability

    Science.gov (United States)

    Zhang, Xiao-Xiao; Sharratt, Brenton; Chen, Xi; Wang, Zi-Fa; Liu, Lian-You; Guo, Yu-Hong; Li, Jie; Chen, Huan-Sheng; Yang, Wen-Yi

    2017-02-01

    Eolian dust transport and deposition are important geophysical processes which influence global bio-geochemical cycles. Currently, reliable deposition data are scarce in central and east Asia. Located at the boundary of central and east Asia, Xinjiang Province of northwestern China has long played a strategic role in cultural and economic trade between Asia and Europe. In this paper, we investigated the spatial distribution and temporal variation in dust deposition and ambient PM10 (particulate matter in aerodynamic diameter ≤ 10 µm) concentration from 2000 to 2013 in Xinjiang Province. This variation was assessed using environmental monitoring records from 14 stations in the province. Over the 14 years, annual average dust deposition across stations in the province ranged from 255.7 to 421.4 t km-2. Annual dust deposition was greater in southern Xinjiang (663.6 t km-2) than northern (147.8 t km-2) and eastern Xinjiang (194.9 t km-2). Annual average PM10 concentration across stations in the province varied from 100 to 196 µg m-3 and was 70, 115 and 239 µg m-3 in northern, eastern and southern Xinjiang, respectively. The highest annual dust deposition (1394.1 t km-2) and ambient PM10 concentration (352 µg m-3) were observed in Hotan, which is located in southern Xinjiang and at the southern boundary of the Taklamakan Desert. Dust deposition was more intense during the spring and summer than other seasons. PM10 was the main air pollutant that significantly influenced regional air quality. Annual average dust deposition increased logarithmically with ambient PM10 concentration (R2 ≥ 0.81). While the annual average dust storm frequency remained unchanged from 2000 to 2013, there was a positive relationship between dust storm days and dust deposition and PM10 concentration across stations. This study suggests that sand storms are a major factor affecting the temporal variability and spatial distribution of dust deposition in northwest China.

  15. Properties and Spatial Distribution of Dust Emission in the Crab Nebula

    Science.gov (United States)

    Sonneborn, G.; Temim, T.; Dwek, E.; Arendt, R.; Gehrz, R.; Slane, P.

    2011-01-01

    The nature and quantity of dust produced in supernovae (SNe) is still poorly understood. Recent IR observations of freshly-formed dust in supernova remnants (SNRs) have yielded significantly lower dust masses than predicted by theoretical models and observations high-redshift galaxies. The Crab Nebula's pulsar wind is thought to be sweeping up freshly-formed SN dust along with the SN ejecta. The evidence for this dust was found in the form of an IR bump in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially-resolved emission spectra of dust in the Crab Nebula acquired with the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from both sides of the expanding nebula, including emission from [S III], [Si II], [Ne II], [Ne III], [Ne V], [Ar III], [Ar V], [Fe II], and [Ni II]. We extrapolated a synchrotron spectral data cube from the Spitzer 3.6 and 4.5 micron images, and subtracted this contribution from our 15-40 micron spectral data to produce a map of the residual continuum emission from dust. The emission appears to be concentrated along the ejecta filaments and is well described by astronomical silicates at an average temperature of 65 K. The estimated mass of dust in the Crab Nebula is 0.008 solar masses.

  16. Emissions from potential Patagonian dust sources and associated biological response in the Atlantic sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    A. Castagna

    2014-07-01

    Full Text Available The effect of Patagonian dust over primary producers in the Southern Ocean has long been disputed. Here we present new remote sensing evidence in favour of dust mediated biological response and postulate a hypothesis to explain the spatial relation observed. A new remote sensing definition of dust source areas based on the Normalized Difference Vegetation Index (NDVI and Absorbing Aerosol Index (AAI correlation is presented and interannual variation in AAI is evaluated within the source regions as a proxy for dust activity. Correlation of this data with annual chlorophyll concentration, phytoplankton biomass, and diatom dominance reveals a spatially coherent latitudinal band of positive correlation concentrated between the Polar Front and the Subtropical Front. This pattern is restricted to western areas in the biomass correlation and extends toward Africa for the chlorophyll and diatom correlation. This region is equivalent to the area of the Subantarctic Mode Water formation, characterized by a ratio Si : N ≪ 1 in late summer, an unfavourable condition for diatom development, especially under iron limitation. Therefore, due to Si–Fe co-limitation, the positive correlation could be the consequence of an enhanced sensibility of this area to external iron addition for diatom growth. For the Argentinean shelf-break, is not clear whether direct dust input and/or wind stress driving water masses upwelling could be responsible for the positive correlation.

  17. Emissions from potential Patagonian dust sources and associated biological response in the Atlantic sector of the Southern Ocean

    Science.gov (United States)

    Castagna, A.; Evangelista, H.; Tilstra, L. G.; Kerr, R.

    2014-07-01

    The effect of Patagonian dust over primary producers in the Southern Ocean has long been disputed. Here we present new remote sensing evidence in favour of dust mediated biological response and postulate a hypothesis to explain the spatial relation observed. A new remote sensing definition of dust source areas based on the Normalized Difference Vegetation Index (NDVI) and Absorbing Aerosol Index (AAI) correlation is presented and interannual variation in AAI is evaluated within the source regions as a proxy for dust activity. Correlation of this data with annual chlorophyll concentration, phytoplankton biomass, and diatom dominance reveals a spatially coherent latitudinal band of positive correlation concentrated between the Polar Front and the Subtropical Front. This pattern is restricted to western areas in the biomass correlation and extends toward Africa for the chlorophyll and diatom correlation. This region is equivalent to the area of the Subantarctic Mode Water formation, characterized by a ratio Si : N ≪ 1 in late summer, an unfavourable condition for diatom development, especially under iron limitation. Therefore, due to Si-Fe co-limitation, the positive correlation could be the consequence of an enhanced sensibility of this area to external iron addition for diatom growth. For the Argentinean shelf-break, is not clear whether direct dust input and/or wind stress driving water masses upwelling could be responsible for the positive correlation.

  18. Spatially resolved stellar, dust and gas properties of the post-interacting Whirlpool Galaxy system

    CERN Document Server

    Cooper, Erin Mentuch; Foyle, Kelly; Bendo, George; Koda, Jin; Baes, Marten; Boquien, Médéric; Boselli, Alessandro; Ciesla, Laure; Cooray, Asantha; Eales, Steve; Galametz, Maud; Lebouteiller, Vianney; Parkin, Tara; Roussel, Hélène; Sauvage, Marc; Spinoglio, Luigi; Smith, Matthew W L

    2012-01-01

    Using infrared imaging from the Herschel Space Observatory, observed as part of the VNGS, we investigate the spatially resolved dust properties of the interacting Whirlpool galaxy system (NGC 5194 and NGC 5195), on physical scales of 1 kpc. Spectral energy distribution modelling of the new infrared images in combination with archival optical, near- through mid-infrared images confirms that both galaxies underwent a burst of star formation ~370-480 Myr ago and provides spatially resolved maps of the stellar and dust mass surface densities. The resulting average dust-to-stellar mass ratios are comparable to other spiral and spheroidal galaxies studied with Herschel, with NGC 5194 at log M(dust)/M(star)= -2.5+/-0.2 and NGC 5195 at log M(dust)/M(star)= -3.5+/-0.3. The dust-to-stellar mass ratio is constant across NGC 5194 suggesting the stellar and dust components are coupled. In contrast, the mass ratio increases with radius in NGC 5195 with decreasing stellar mass density. Archival mass surface density maps of ...

  19. The spatial concentration of dust emissions measured by using 3D scanning lidar in the open storage yards of steel-making company

    Science.gov (United States)

    Chiang, Chih-Wei; Chiang, Hong-Wei; Chou, Huann-Ming; Sun, Shu-Huang; Lee, Jiann-Shen

    2017-06-01

    The wind-blown dust emissions frequently occur in the open storage yards of steel-making companies. Tracking the dust source and monitoring their dispersion are rather difficult. This type of open-air storage yards poses many environmental hazards. The 3-D scanning lidar system is effective in environmental monitoring (e.g., dust) with high temporal and spatial resolution, which is lacking in traditional ground-based measurement. The objective of this paper is to make an attempt for the flux estimation of dust concentration by using lidar system. Further, we investigate the dynamical process of dust and their relationship with local air quality monitoring data. The results show that the material storage erosion by wind ( 3.6 m/s) could cause dust to elevate up to 20m height above the material storage, and produces the flux of dust around 674 mg/s. The flux of dust is proportional to the dust mass concentration (PM10) measured by commercial ambient particular monitors.

  20. Source, route and effect of Asian sand dust on environment and the oceans

    Institute of Scientific and Technical Information of China (English)

    Kai Zhang; Fahe Chai; Renjian Zhang; Zhigang Xue

    2010-01-01

    We summarize in this overview achievements in current research frontiers in Asian sand dust with emphasis on the method for sand dust research,the sources of sand dust aerosols,emission of sand dust,mechanism of sand dust weather,chemical transformation during transport,and influences on climatic environment and oceans.Our main results show that most of Asian sand dust comes from Mongolia,the Gobi Desert,arid and semiarid desert areas in northwest China,which is divided into initial sources and enhanced sources.Half of the global production of dust originates from Asian dust source regions.Asian dust weather is so immense that it can cover a 5-7-day journey from the sources to the Korean Peninsula,Japan Islands,and the Pacific Ocean to even impact North America.Asian dust weather plays an active role in the biogeochemical cycles of trace elements in the mid-latitude Northern Hemisphere.

  1. The dust mass in Cassiopeia A from a spatially resolved Herschel analysis

    Science.gov (United States)

    De Looze, I.; Barlow, M. J.; Swinyard, B. M.; Rho, J.; Gomez, H. L.; Matsuura, M.; Wesson, R.

    2017-03-01

    Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M⊙), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g. SN 1987A, Crab nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ∼330-yr old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ∼0.6 arcmin for this 5 arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 μm with a four-component interstellar medium and supernova (SN) dust model. We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 M⊙ of silicate grains freshly produced in the SNR, with a lower limit of ≥0.1-0.2 M⊙. For a mixture of 50 per cent of silicate-type grains and 50 per cent of carbonaceous grains, we derive a total SN dust mass between 0.4 and 0.6 M⊙. These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of SN-dominated dust production at high redshifts. We furthermore derive an interstellar extinction map for the field around Cas A which towards Cas A gives average values of AV = 6-8 mag, up to a maximum of AV = 15 mag.

  2. Perceived loudness of spatially distributed sound sources

    DEFF Research Database (Denmark)

    Song, Woo-keun; Ellermeier, Wolfgang; Minnaar, Pauli

    2005-01-01

    psychoacoustic attributes into account. Therefore, a method for deriving loudness maps was developed in an earlier study [Song, Internoise2004, paper 271]. The present experiment investigates to which extent perceived loudness depends on the distribution of individual sound sources. Three loudspeakers were...... of a microphone (monaural) and a dummy head (binaural) placed at the listening position. The results show that while loudness metrics fared well in predicting perceived loudness for any single-sound condition, they failed to predict loudness for two simultaneous sounds. This suggests that current loudness...... modelling will have to be extended to take the spatial distribution of sources into account....

  3. Advances in Mineral Dust Source Composition Measurement with Imaging Spectroscopy at the Salton Sea, CA

    Science.gov (United States)

    Green, R. O.; Realmuto, V. J.; Thompson, D. R.; Mahowald, N. M.; Pérez García-Pando, C.; Miller, R. L.; Clark, R. N.; Swayze, G. A.; Okin, G. S.

    2015-12-01

    Mineral dust emitted from the Earth's surface is a principal contributor to direct radiative forcing over the arid regions, where shifts in climate have a significant impact on agriculture, precipitation, and desert encroachment around the globe. Dust particles contribute to both positive and negative forcing, depending on the composition of the particles. Particle composition is a function of the surface mineralogy of dust source regions, but poor knowledge of surface mineralogy on regional to global scales limits the skill of Earth System models to predict shifts in regional climate around the globe. Earth System models include the source, emission, transport and deposition phases of the dust cycle. In addition to direct radiative forcing contributions, mineral dust impacts include indirect radiative forcing, modification of the albedo and melting rates of snow and ice, kinetics of tropospheric photochemistry, formation and deposition of acidic aerosols, supply of nutrients to aquatic and terrestrial ecosystems, and impact on human health and safety. We demonstrate the ability to map mineral dust source composition in the Salton Sea dust source region with imaging spectroscopy measurements acquired as part of the NASA HyspIRI preparatory airborne campaign. These new spectroscopically derived compositional measurements provide a six orders of magnitude improvement over current atlases for this dust source region and provide a pathfinder example for a remote measurement approach to address this critical dust composition gap for global Earth System models.

  4. The dust mass in Cassiopeia A from a spatially resolved Herschel analysis

    CERN Document Server

    De Looze, I; Swinyard, B M; Rho, J; Gomez, H L; Matsuura, M; Wesson, R

    2016-01-01

    Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 Msun), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g., SN1987A, Crab Nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ~330-year old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ~0.6 arcmin for this 5 arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 micron with a four-component interstellar medium (ISM) and supernova (SN) dust model. We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of ...

  5. Properties and Spatial Distribution of Dust Emission in the Crab Nebula

    CERN Document Server

    Temim, Tea; Dwek, Eli; Arendt, Richard G; Gehrz, Robert D; Slane, Patrick; Roellig, Thomas L

    2012-01-01

    Recent infrared (IR) observations of freshly-formed dust in supernova remnants (SNRs) have yielded significantly lower dust masses than predicted by theoretical models and measured from high redshift observations. The Crab Nebula's pulsar wind is thought to be sweeping up freshly-formed supernova (SN) dust along with the ejected gas. The evidence for this dust was found in the form of an IR excess in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially resolved emission spectra of dust in the Crab Nebula acquired with the Infrared Spectrograph aboard the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from from S, Si, Ne, Ar, O, Fe, and Ni. We derived a synchrotron spectral map from the 3.6 and 4.5 microns images, and subtracted this contribution from our data to produce a map of the residual continuum emission from dust. The du...

  6. The spatial distribution of mineral dust and its shortwave radiative forcing over North Africa: modeling sensitivities to dust emissions and aerosol size treatments

    Directory of Open Access Journals (Sweden)

    C. Zhao

    2010-04-01

    Full Text Available A fully coupled meteorology-chemistry-aerosol model (WRF-Chem is applied to simulate mineral dust and its shortwave (SW radiative forcing over North Africa. Two dust emission schemes (GOCART and DUSTRAN and two aerosol models (MADE/SORGAM and MOSAIC are adopted in simulations to investigate the modeling sensitivities to dust emissions and aerosol size treatments. The modeled size distribution and spatial variability of mineral dust and its radiative properties are evaluated using measurements (ground-based, aircraft, and satellites during the AMMA SOP0 campaign from 6 January to 3 February of 2006 (the SOP0 period over North Africa. Two dust emission schemes generally simulate similar spatial distributions and temporal evolutions of dust emissions. Simulations using the GOCART scheme with different initial (emitted dust size distributions show that the difference of initial dust size distributions can result in significant difference (up to ~50% in simulating SW dust heating and SW dust radiative forcing at the surface over the Sahel region. The modal approach of MADE/SORGAM retains 25% more fine dust particles (radius <1.25 μm but 8% less coarse dust particles (radius >1.25 μm than the sectional approach of MOSAIC in simulations using the same size-resolved dust emissions. Consequently, MADE/SORGAM simulates 11% higher AOD, up to 13% lower SW dust heating rate, and 15% larger (more negative SW dust radiative forcing at the surface than MOSAIC over the Sahel region. In the daytime of the SOP0 period, the model simulations show that mineral dust heats the lower atmosphere (1–3 km with a maximum rate of 0.8±0.5 K day−1 below 1 km and reduces the downwelling SW radiation at the surface by up to 58 W m−2 over the Sahel region. This highlights the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, the WRF-Chem simulations can

  7. Road dust emission sources and assessment of street washing effect

    NARCIS (Netherlands)

    Karanasiou, A.; Amato, F.; Moreno, T.; Lumbreras, J.; Borge, R.; Linares, C.; Boldo, E.; Alastuey, A.; Querol, X.

    2014-01-01

    Although previous studies report on the effect of street washing on ambient particulate matter levels, there is a lack of studies investigating the results of street washing on the emission strength of road dust. A sampling campaign was conducted in Madrid urban area during July 2009 where road dust

  8. The spatial distribution of mineral dust and its shortwave radiative forcing over North Africa: modeling sensitivities to dust emissions and aerosol size treatments

    Directory of Open Access Journals (Sweden)

    C. Zhao

    2010-09-01

    Full Text Available A fully coupled meteorology-chemistry-aerosol model (WRF-Chem is applied to simulate mineral dust and its shortwave (SW radiative forcing over North Africa. Two dust emission schemes (GOCART and DUSTRAN and two aerosol models (MADE/SORGAM and MOSAIC are adopted in simulations to investigate the modeling sensitivities to dust emissions and aerosol size treatments. The modeled size distribution and spatial variability of mineral dust and its radiative properties are evaluated using measurements (ground-based, aircraft, and satellites during the AMMA SOP0 campaign from 6 January to 3 February of 2006 (the SOP0 period over North Africa. Two dust emission schemes generally simulate similar spatial distributions and temporal evolutions of dust emissions. Simulations using the GOCART scheme with different initial (emitted dust size distributions require ~40% difference in total emitted dust mass to produce similar SW radiative forcing of dust over the Sahel region. The modal approach of MADE/SORGAM retains 25% more fine dust particles (radius<1.25 μm but 8% less coarse dust particles (radius>1.25 μm than the sectional approach of MOSAIC in simulations using the same size-resolved dust emissions. Consequently, MADE/SORGAM simulates 11% higher AOD, up to 13% lower SW dust heating rate, and 15% larger (more negative SW dust radiative forcing at the surface than MOSAIC over the Sahel region. In the daytime of the SOP0 period, the model simulations show that the mineral dust heats the lower atmosphere with an average rate of 0.8 ± 0.5 K day−1 over the Niamey vicinity and 0.5 ± 0.2 K day−1 over North Africa and reduces the downwelling SW radiation at the surface by up to 58 W m−2 with an average of 22 W m−2 over North Africa. This highlights the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, the WRF

  9. Long-term dust aerosol production from natural sources in Iceland.

    Science.gov (United States)

    Dagsson-Waldhauserova, Pavla; Arnalds, Olafur; Olafsson, Haraldur

    2017-02-01

    Iceland is a volcanic island in the North Atlantic Ocean with maritime climate. In spite of moist climate, large areas are with limited vegetation cover where >40% of Iceland is classified with considerable to very severe erosion and 21% of Iceland is volcanic sandy deserts. Not only do natural emissions from these sources influenced by strong winds affect regional air quality in Iceland ("Reykjavik haze"), but dust particles are transported over the Atlantic ocean and Arctic Ocean >1000 km at times. The aim of this paper is to place Icelandic dust production area into international perspective, present long-term frequency of dust storm events in northeast Iceland, and estimate dust aerosol concentrations during reported dust events. Meteorological observations with dust presence codes and related visibility were used to identify the frequency and the long-term changes in dust production in northeast Iceland. There were annually 16.4 days on average with reported dust observations on weather stations within the northeastern erosion area, indicating extreme dust plume activity and erosion within the northeastern deserts, even though the area is covered with snow during the major part of winter. During the 2000s the highest occurrence of dust events in six decades was reported. We have measured saltation and Aeolian transport during dust/volcanic ash storms in Iceland, which give some of the most intense wind erosion events ever measured. Icelandic dust affects the ecosystems over much of Iceland and causes regional haze. It is likely to affect the ecosystems of the oceans around Iceland, and it brings dust that lowers the albedo of the Icelandic glaciers, increasing melt-off due to global warming. The study indicates that Icelandic dust may contribute to the Arctic air pollution.

  10. Enzyme activities and arylsulfatase protein content of dust and the soil source: biochemical fingerprints?

    Science.gov (United States)

    Acosta-Martínez, V; Zobeck, T M

    2004-01-01

    Little is known about the potential of enzyme activities, which are sensitive to soil properties and management, for the characterization of dust properties. Enzyme activities may be among the dust properties key to identifying the soil source of dust. We generated dust (27 and 7 microm) under controlled laboratory conditions from agricultural soils (0-5 cm) with history of continuous cotton (Gossypium hirsutum L.) or cotton rotated with peanut (Arachis hypogaea L.), sorghum [Sorghum bicolor (L.) Moench], rye (Secale cereale L.), or wheat (Triticum aestivum L.) under different water management (irrigated or dryland) and tillage (conservation or conventional) systems. The 27- and 7-microm dust samples showed activities of beta-glucosidase, alkaline phosphatase, and arylsulfatase, which are related to cellulose degradation and phosphorus and sulfur mineralization in soil, respectively. Dust samples generated from a loam and sandy clay loam showed higher enzyme activities compared with dust samples from a fine sandy loam. Enzyme activities of dust samples were significantly correlated to the activities of the soil source with r > 0.74 (P < 0.01). The arylsulfatase proteins contents of the soils (0.04-0.65 mg protein kg(-1) soil) were lower than values reported for soils from other regions, but still dust contained arylsulfatase protein. The three enzyme activities studied, as a group, separated the dust samples due to the crop rotation or tillage practice history of the soil source. The results indicated that the enzyme activities of dust will aid in providing better characterization of dust properties and expanding our understanding of soil and air quality impacts related to wind erosion.

  11. Geochemical characterization of critical dust source regions in the American West

    Science.gov (United States)

    Aarons, Sarah M.; Blakowski, Molly A.; Aciego, Sarah M.; Stevenson, Emily I.; Sims, Kenneth W. W.; Scott, Sean R.; Aarons, Charles

    2017-10-01

    The generation, transport, and deposition of mineral dust are detectable in paleoclimate records from land, ocean, and ice, providing valuable insight into earth surface conditions and cycles on a range of timescales. Dust deposited in marine and terrestrial ecosystems can provide critical nutrients to nutrient-limited ecosystems, and variations in dust provenance can indicate changes in dust production, sources and transport pathways as a function of climate variability and land use change. Thus, temporal changes in locations of dust source areas and transport pathways have implications for understanding interactions between mineral dust, global climate, and biogeochemical cycles. This work characterizes dust from areas in the American West known for dust events and/or affected by increasing human settlement and livestock grazing during the last 150 years. Dust generation and uplift from these dust source areas depends on climate and land use practices, and the relative contribution of dust has likely changed since the expansion of industrialization and agriculture into the western United States. We present elemental and isotopic analysis of 28 potential dust source area samples analyzed using Thermal Ionization Mass Spectrometry (TIMS) for 87Sr/86Sr and 143Nd/144Nd composition and Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS) for 176Hf/177Hf composition, and ICPMS for major and trace element concentrations. We find significant variability in the Sr, Nd, and Hf isotope compositions of potential source areas of dust throughout western North America, ranging from 87Sr/86Sr = 0.703699 to 0.740236, εNd = -26.6 to 2.4, and εHf = -21.7 to -0.1. We also report differences in the trace metal and phosphorus concentrations in the geologic provinces sampled. This research provides an important resource for the geochemical tracing of dust sources and sinks in western North America, and will aid in modeling the biogeochemical impacts of increased

  12. Satellite Monitoring of Long-Range Transport of Asian Dust Storms from Sources to Sinks

    Science.gov (United States)

    Hsu, N.; Tsay, S.; Jeong, M.; King, M.; Holben, B.

    2007-05-01

    satellite products will allow scientists to determine quantitatively the aerosol properties near sources and their evolution along transport pathway using high spatial resolution measurements from SeaWiFS and MODIS-like instruments. We will also utilize the multiyear satellite measurements from MODIS and SeaWiFS to investigate the interannual variability of source strength, pathway, and radia-tive forcing associated with these dust outbreaks in East Asia.

  13. Dust transport from non-East Asian sources to the North Pacific

    Science.gov (United States)

    Hsu, S.; Huh, C.; Lin, C.; Chen, W.; Mahowald, N. M.; Liu, S. C.; Chou, C. C.; Liang, M.; Tsai, C.; Lin, F.; Chen, J.; Huang, Y.

    2012-12-01

    It is generally thought that East Asia dominates the supply of eolian dust to the North Pacific. Here we show the first data-based evidence of dust primarily from non-East Asian sources even during March 2010 when a super dust storm from East Asia struck the western Pacific. Chemical characteristics of aerosol samples collected at a high-mountain site in Taiwan show variable inputs from eolian dust and biomass burning. From backward trajectory analyses, satellite observation and model simulation, dust origins can be traced to the Middle East and North Africa, suggesting an integrated source from the global dust belt. Our global model results demonstrate that dust deposition in the North Pacific is primarily contributed by non-East Asian sources with an eastward decrease along the Westerlies. Time-series of aerosol composition at Mt. Lulin: (A) 210Pb and biomass burning potassium (KBB), (B) 7Be and aluminum. Also shown (in A) are daily mean O3 and CO , hourly relative humidity (gray curve/area) and (in B) daily rainfall (yellow bars) measured at Taiwan EPA's Lulin Atmospheric Background Station (LABS), ~25 m southeast of our aerosol sampling site. Results from the MATCH model showing (A) total annual dust deposition fluxes, and (B) fraction of the total deposition attributable to East Asian sources over the North Pacific.

  14. Sources and pathways of dust during the Australian "Millennium Drought" decade

    Science.gov (United States)

    O'Loingsigh, Tadhg; Chubb, Thomas; Baddock, Matthew; Kelly, Tyler; Tapper, Nigel J.; De Deckker, Patrick; McTainsh, Grant

    2017-01-01

    From the late 1990s to mid-2010, Australia was affected by a prolonged period of drought, the "Millennium Drought," during which numerous severe dust storms crossed the continent. We inspect this period to produce the first continental-scale climatology of air-parcel trajectories that is specific to dust and use it to gain new insights into dust transport dynamics over the eastern half of Australia. The analysis is based upon dust arrival times from airport meteorological observations made at nine mostly coastal cities for 2000-2009. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to calculate 1.26 million backward trajectories from receptor cities, with only those trajectories associated with a dust storm observation considered in the analysis of dust transport. To tie dust trajectories from receptors to likely emission sources, trajectories were linked to six known major dust source regions in and around the Lake Eyre Basin. The Lake Eyre North ephemeral lake system, alluvial-dominated Channel Country, and agricultural Mallee-Riverina regions emerge as important sources for the period, providing variable contributions to different parts of the seaboard as controlled by different front-related wind systems. Our study also provides new detail regarding dust pathways from continental Australia. For the Millennium Drought we identify that the broadly established Southeast Dust Path may be more accurately subdivided into three active pathways, driven by prefrontal northerly winds and a variation in the influence of frontal westerlies. The detail of these pathways has implications for dust delivery from specific Australian sources to different marine environments.

  15. Sensitivity of WRF-chem predictions to dust source function specification in West Asia

    Science.gov (United States)

    Nabavi, Seyed Omid; Haimberger, Leopold; Samimi, Cyrus

    2017-02-01

    Dust storms tend to form in sparsely populated areas covered by only few observations. Dust source maps, known as source functions, are used in dust models to allocate a certain potential of dust release to each place. Recent research showed that the well known Ginoux source function (GSF), currently used in Weather Research and Forecasting Model coupled with Chemistry (WRF-chem), exhibits large errors over some regions in West Asia, particularly near the IRAQ/Syrian border. This study aims to improve the specification of this critical part of dust forecasts. A new source function based on multi-year analysis of satellite observations, called West Asia source function (WASF), is therefore proposed to raise the quality of WRF-chem predictions in the region. WASF has been implemented in three dust schemes of WRF-chem. Remotely sensed and ground-based observations have been used to verify the horizontal and vertical extent and location of simulated dust clouds. Results indicate that WRF-chem performance is significantly improved in many areas after the implementation of WASF. The modified runs (long term simulations over the summers 2008-2012, using nudging) have yielded an average increase of Spearman correlation between observed and forecast aerosol optical thickness by 12-16 percent points compared to control runs with standard source functions. They even outperform MACC and DREAM dust simulations over many dust source regions. However, the quality of the forecasts decreased with distance from sources, probably due to deficiencies in the transport and deposition characteristics of the forecast model in these areas.

  16. Dust deposition: iron source or sink? A case study

    OpenAIRE

    Ye, Y.; Wagener, T.; Völker, C.; Guieu, C.; D. A. Wolf-Gladrow

    2011-01-01

    A significant decrease of dissolved iron (DFe) concentration has been observed after dust addition into mesocosms during the DUst experiment in a low Nutrient low chlorophyll Ecosystem (DUNE), carried out in the summer of 2008. Due to low biological productivity at the experiment site, biological consumption of iron can not explain the magnitude of DFe decrease. To understand processes regulating the observed DFe variation, we simulated the experiment using a one-dimensional model of the Fe b...

  17. Causes of dust size variability in central East Antarctica (Dome B): Atmospheric transport from expanded South American sources during Marine Isotope Stage 2

    Science.gov (United States)

    Delmonte, Barbara; Paleari, Chiara Ileana; Andò, Sergio; Garzanti, Eduardo; Andersson, Per Sune; Petit, Jean Robert; Crosta, Xavier; Narcisi, Biancamaria; Baroni, Carlo; Salvatore, Maria Cristina; Baccolo, Giovanni; Maggi, Valter

    2017-07-01

    We here investigate the spatial and temporal variability of eolian dust particle sorting recorded in the Dome B (77° 05‧ S, 94° 55' E) ice core, central East Antarctica, during Marine Isotope Stage (MIS) 2. We address the question whether such changes reflect variable transport pathways from a unique source area or rather a variable apportionment from diverse Southern Hemisphere sources transported at different elevation in the troposphere. The Sr-Nd radiogenic isotope composition of glacial dust samples as well as single-particle Raman mineralogy support the hypothesis of a single dust provenance both for coarse and fine mode dust events at Dome B. The southern South American provenance of glacial dust in Antarctica deduced from these results indicate a dust composition coherent with a mixture of volcanic material and minerals derived from metamorphic and plutonic rocks. Additionally, Dome B glacial samples contain aragonite particles along with diatom valves of marine benthic/epiphytic species and freshwater species living today in the northern Antarctic Peninsula and southern South America. These data suggest contribution from the exposed Patagonian continental shelf and glacial outwash plains of southern Patagonia at the time when sea level reached its minimum. Our results confirm that dust sorting is controlled by the relative intensity of the two main patterns of tropospheric dust transport onto the inner Plateau, i.e. fast low-level advection and long-range high-altitude transport including air subsidence over Antarctica.

  18. Soil organic carbon dust emission: an omitted global source of atmospheric CO2.

    Science.gov (United States)

    Chappell, Adrian; Webb, Nicholas P; Butler, Harry J; Strong, Craig L; McTainsh, Grant H; Leys, John F; Viscarra Rossel, Raphael A

    2013-10-01

    Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO(2)) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and transporting C dust quickly offshore; augmenting the net loss of C from terrestrial systems. However, the contribution of wind erosion to rates of C release and sequestration is poorly understood. Here, we describe how SOC dust emission is omitted from national C accounting, is an underestimated source of CO(2) and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO(2) emission. We developed a first approximation to SOC enrichment for a well-established dust emission model and quantified SOC dust emission for Australia (5.83 Tg CO(2)-e yr(-1)) and Australian agricultural soils (0.4 Tg CO(2)-e yr(-1)). These amount to underestimates for CO(2) emissions of ≈10% from combined C pools in Australia (year = 2000), ≈5% from Australian Rangelands and ≈3% of Australian Agricultural Soils by Kyoto Accounting. Northern hemisphere countries with greater dust emission than Australia are also likely to have much larger SOC dust emission. Therefore, omission of SOC dust emission likely represents a considerable underestimate from those nations' C accounts. We suggest that the omission of SOC dust emission from C cycling and C accounting is a significant global source of uncertainty. Tracing the fate of wind-eroded SOC in the dust cycle is therefore essential to quantify the release of CO(2) from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks.

  19. Ice Nucleating Particle Properties in the Saharan Air Layer Close to the Dust Source

    Science.gov (United States)

    Boose, Y.; Garcia, I. M.; Rodríguez, S.; Linke, C.; Schnaiter, M.; Nickovic, S.; Lohmann, U.; Kanji, Z. A.; Sierau, B.

    2015-12-01

    In August 2013 and 2014 measurements of ice nucleating particle (INP) concentrations, aerosol particle size distributions, chemistry and fluorescence were conducted at the Izaña Atmospheric Observatory located at 2373 m asl on Tenerife, west off the African shore. During summer, the observatory is frequently within the Saharan Air Layer and thus often exposed to dust. Absolute INP concentrations and activated fractions at T=-40 to -15°C and RHi=100-150 % were measured. In this study, we discuss the in-situ measured INP properties with respect to changes in the chemical composition, the biological content, the source regions as well as transport pathways and thus aging processes of the dust aerosol. For the first time, ice crystal residues were also analyzed with regard to biological content by means of their autofluorescence signal close to a major dust source region. Airborne dust samples were collected with a cyclone for additional offline analysis in the laboratory under similar conditions as in the field. Both, in-situ and offline dust samples were chemically characterized using single-particle mass spectrometry. The DREAM8 dust model extended with dust mineral fractions was run to simulate meteorological and dust aerosol conditions for ice nucleation. Results show that the background aerosol at Izaña was dominated by carbonaceous particles, which were hardly ice-active under the investigated conditions. When Saharan dust was present, INP concentrations increased by up to two orders of magnitude even at water subsaturated conditions at T≤-25°C. Differences in the ice-activated fraction were found between different dust periods which seem to be linked to variations in the aerosol chemical composition (dust mixed with changing fractions of sea salt and differences in the dust aerosol itself). Furthermore, two biomass burning events in 2014 were identified which led to very low INP concentrations under the investigated temperature and relative humidity

  20. Heavy metals in road dust from Xiandao District, Changsha City, China: characteristics, health risk assessment, and integrated source identification.

    Science.gov (United States)

    Li, Fei; Zhang, Jingdong; Huang, Jinhui; Huang, Dawei; Yang, Jun; Song, Yongwei; Zeng, Guangming

    2016-07-01

    The physicochemical properties and the contents of metals (Cu, Zn, Pb, Cd, Cr, and Fe) in 51 road dust samples from Xiandao District (XDD) were investigated. Enrichment factor (EF), multivariate statistics, geostatistics, and health risk assessment model were adopted to study the spatial pollution pattern and to identify the priority pollutants and regions of concern and sources of studied metals. The mean EFs revealed the following order: Cd > Zn ≈ Pb ≈ Cu > Cr. For non-carcinogenic effects, the exposure pathway which resulted in the highest levels of exposure risk for children and adults was ingestion, followed by dermal contact and inhalation. Hazard index (HI) values for the studied metals at each site were within the safe level of 1 except maximum HI Cr (1.08) for children. The carcinogenic risk (CR) for Cd and Cr at each site was within the acceptable risk level (1E-06) except CR Cr (1.08E-06) for children in the road intersection between the Changchang highway and the Yuelin highway. Cr was identified as the priority pollutant followed by Pb and Cd with consideration of the local population distribution. Spatially, northwest and northeast of XDD were regarded as the priority regions of concern. Results based on the proposed integrated source identification method indicated that Pb was probably sourced from traffic-related sources, Cd was associated with the dust organic material mainly originated from industrial sources, and Cr was mainly derived from both sources.

  1. Contribution of mineral dust sources to street side ambient and suspension PM10 samples

    Science.gov (United States)

    Kupiainen, Kaarle; Ritola, Roosa; Stojiljkovic, Ana; Pirjola, Liisa; Malinen, Aleksi; Niemi, Jarkko

    2016-12-01

    The aim of this study was to determine the relative contributions of mineral dust sources, particularly pavement wear and traction sanding in the PM10 samples collected from 1) street side ambient air and 2) street dust suspension emission samples. The study was conducted between autumn 2011 and spring 2012 at Suurmetsäntie in Helsinki, Finland. The results showed that dust from pavement aggregates was the largest source during spring, accounting for 40-50 percent of the particulate matter in the air and suspension samples. Based on studies on formation of dust, major source of the dust from pavement aggregates is the wear by studded tyres. Traction sanding (1-5.6 mm wet sieved crushed stone) and road salting (NaCl) were applied frequently during the winter 2011/2012. Sanding material explained about 25 percent of the street dust in the air and suspension samples. Traction sanding is estimated to account for approximately few percent of the pavement dust via "the sandpaper effect". Effect of road salt was few percent in the samples. The source contributions from pavement and traction sanding observed in spring 2012 at Suurmetsäntie are similar to what has been estimated in a previous study conducted in the early 2000s in Finland. The general perception in Finland has been that traction sanding is the main source of airborne street dust. Studies conducted in 2000s and the results of this study, however, indicate that traction sanding has been an important but not the main source of dust in PM10 even in winters with extensive use of sanding for traction control.

  2. From Source to City: Particulate Matter Concentration and Size Distribution Data from an Icelandic Dust Storm

    Science.gov (United States)

    Thorsteinsson, T.; Mockford, T.; Bullard, J. E.

    2015-12-01

    Dust storms are the source of particulate matter in 20%-25% of the cases in which the PM10health limit is exceeded in Reykjavik; which occurred approximately 20 times a year in 2005-2010. Some of the most active source areas for dust storms in Iceland, contributing to the particulate matter load in Reykjavik, are on the south coast of Iceland, with more than 20 dust storm days per year (in 2002-2011). Measurements of particle matter concentration and size distribution were recorded at Markarfljot in May and June 2015. Markarfljot is a glacial river that is fed by Eyjafjallajokull and Myrdalsjokull, and the downstream sandur areas have been shown to be significant dust sources. Particulate matter concentration during dust storms was recorded on the sandur area using a TSI DustTrak DRX Aerosol Monitor 8533 and particle size data was recorded using a TSI Optical Particle Sizer 3330 (OPS). Wind speed was measured using cup anemometers at five heights. Particle size measured at the source area shows an extremely fine dust creation, PM1 concentration reaching over 5000 μg/m3 and accounting for most of the mass. This is potentially due to sand particles chipping during saltation instead of breaking uniformly. Dust events occurring during easterly winds were captured by two permanent PM10 aerosol monitoring stations in Reykjavik (140 km west of Markarfljot) suggesting the regional nature of these events. OPS measurements from Reykjavik also provide an interesting comparison of particle size distribution from source to city. Dust storms contribute to the particular matter pollution in Reykjavik and their small particle size, at least from this source area, might be a serious health concern.

  3. Spatially-resolved dust maps from Balmer decrements in galaxies at z~1.4

    CERN Document Server

    Nelson, Erica June; Momcheva, Ivelina G; Brammer, Gabriel B; Wuyts, Stijn; Franx, Marijn; Schreiber, Natascha M Forster; Whitaker, Katherine E; Skelton, Rosalind E

    2015-01-01

    We derive average radial gradients in the dust attenuation towards HII regions in 609 galaxies at z~1.4, using measurements of the Balmer decrement out to r~3kpc. The Balmer decrements are derived from spatially resolved maps of Halpha and Hbeta emission from the 3D-HST survey. We find that with increasing stellar mass (M) both the normalization and strength of the gradient in dust attenuation increases. Galaxies with a mean mass of = 9.2Msun have little dust attenuation at all radii, whereas galaxies with = 10.2Msun have dust attenuation toward Halpha A(Halpha)~2mag in their central regions. We parameterize this as A(Halpha) = b + c log(r), with b = 0.9 + 1.0 log(M10), c = -1.9 - 2.2 log(M10), r in kpc, and M10 the stellar mass in units of 10^10Msun. This expression can be used to correct spatially resolved measurements of Halpha to radial distributions of star formation. When applied to our data, we find that the star formation rates in the central r<1kpc of galaxies in the highest mass bin are ~ 6 Msun...

  4. Estimation of the Threshold Friction Velocities over Various Dust Storm Source Areas in Northwest China

    Institute of Scientific and Technical Information of China (English)

    ZHU Hao; ZHANG Hongsheng

    2010-01-01

    The emission of dust particles into the atmosphere is governed by the aerodynamic and resistant factors, which are quantified by the friction velocity u. and the threshold friction velocity u*t, respectively. The threshold friction velocity u*t influences the vertical dust flux and dust transport. Based on the micro-meteorological data obtained in the springs of 2004 and 2006 over Hunshandake desert area, Loess Plateau, and Gobi desert area, the relationship between dust concentration and friction velocity for the dust events that occurred over Hunshandake desert area was investigated, and the threshold friction velocities over the three different dust source areas were estimated. The results show that the value of dust concentration is low during the pre-emission stage of a dust storm event, and the rapid increase of friction velocity provides favor-able dynamic conditions for dust emission. During the dust emission stage, the dust concentration increases sharply due to mechanical and thermal turbulent mixing. At the calm-down stage, the dust concentration drops nearly linearly with the decreasing friction velocity, on account of the gravitational deposition of larger dust particles. When the dust concentration is higher than 200 μgm-3, it is considered as a dust emission process. According to the criteria, the values of threshold friction velocity over Hunshandake desert area and Gobi region are 0.6 and 0.45 m s-1, respectively. The threshold friction velocity over Loess Plateau depends on the wind direction, due to the complex terrain and inhomogeneous surface. The northwest wind shows the effects of the Mu Us desert in the northwest. The corresponding u*t is 0.35 m s-1. The south wind exhibits the characteristics of the Loess hilly dunes in the south, and the u*t is 0.7 m s-1. The large roughness length of the Loess hilly dunes and the large inter-particle cohesion for the clay soil texture increases the local friction velocity. Different threshold friction

  5. The Mineralogy and Possible Sources of Spring Dust Particles over Beijing

    Institute of Scientific and Technical Information of China (English)

    SHAO Longyi; LI Weijun; XIAO Zhenghui; SUN Zhenquan

    2008-01-01

    A severe Asian Dust Storm (ADS) event occurred on 16-17 April 2006 in northern China. The mineral compositions of dust samples were analyzed using X-ray diffraction (XRD). The results indicated that dust particles of the "17 April 2006" dust storm were dominated by quartz (37.4%) and clay (32.9%), followed by plagioclase (13.7%), with small amounts of calcite, K-feldspar, dolomite, hornblende and gypsum (all less than 10%). The clay fractions with diameter less than 2 fim were separated from the dust storm particles by centrifuging and were further analyzed by XRD. The results revealed that the clay species were mainly illite/smectite mixed layers (I/S) (49%) and illite (34%), with small amount of kaolinite (8%) and chlorite (9%). In order to evaluate the feasibility of using the mineralogy to trace the sources of dust particles, the XRD results of the "17 April 2006" dustfall particles were compared with the dust particles over past years. The results confirmed that the finer dust particles represented by the ADS PMio displayed a smaller quartz/clay ratio than the dustfall particles. The dust storm particles, either from the ADS PMio or from the "17 April 2006" dustfall, showed a lower level of dolomite contents and lower dolomite/clay ratios compared with the non-dust storm dustfall particles. This implies that dolomite could be used to distinguish between the dust contributions from local and non-local sources. Similar trends were found for the gypsum and the gypsum/clay ratio. Moreover, the two dustfall samples had a lower level of illite/smectite mixed layers and a higher level of illite than airborne PMio, implying that the dustfall particles tend to be enriched with illite in its clay fraction.

  6. Mapping erodibility in dust source regions based on geomorphology, meteorology, and remote sensing

    Science.gov (United States)

    Parajuli, Sagar Prasad; Yang, Zong-Liang; Kocurek, Gary

    2014-09-01

    Mineral dust in the atmosphere has implications for Earth's radiation budget, biogeochemical cycles, hydrological cycles, human health, and visibility. Currently, the simulated vertical mass flux of dust differs greatly among the existing dust models. While most of the models utilize an erodibility factor to characterize dust sources, this factor is assumed to be static, without sufficient characterization of the highly heterogeneous and dynamic nature of dust source regions. We present a high-resolution land cover map of the Middle East and North Africa (MENA) in which the terrain is classified by visually examining satellite images obtained from Google Earth Professional and Environmental Systems Research Institute Basemap. We show that the correlation between surface wind speed and Moderate Resolution Imaging Spectroradiometer deep blue aerosol optical depth (AOD) can be used as a proxy for erodibility, which satisfactorily represents the spatiotemporal distribution of soil-derived dust sources. This method also identifies agricultural dust sources and eliminates the satellite-observed dust component that arises from long-range transport, pollution, and biomass burning. The erodible land cover of the MENA region is grouped into nine categories: (1) bedrock: with sediment, (2) sand deposit, (3) sand deposit: on bedrock, (4) sand deposit: stabilized, (5) agricultural and urban area, (6) fluvial system, (7) stony surface, (8) playa/sabkha, and (9) savanna/grassland. Our results indicate that erodibility is linked to the land cover type and has regional variation. An improved land cover map, which explicitly accounts for sediment supply, availability, and transport capacity, may be necessary to represent the highly dynamic nature of dust sources in climate models.

  7. Quantification of dust generating sources in gold and platinum mines.

    CSIR Research Space (South Africa)

    Biffi, M

    2003-03-01

    Full Text Available This report outlines the findings of a study performed to establish the respirable dust generation characteristics of a number of mining activities. A series of thirty-eight tests were performed on five mines in order to establish the respirable...

  8. Development of high-resolution dynamic dust source function - A case study with a strong dust storm in a regional model

    Science.gov (United States)

    Kim, Dongchul; Chin, Mian; Kemp, Eric M.; Tao, Zhining; Peters-Lidard, Christa D.; Ginoux, Paul

    2017-06-01

    A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source. A case study is conducted with an extreme dust storm that occurred in Phoenix, Arizona in 02-03 UTC July 6, 2011. The NU-WRF model with the new high-resolution dynamic dust source is able to successfully capture the dust storm, which was not achieved with the old source identification. However the case study also reveals several challenges in reproducing the time evolution of the short-lived, extreme dust storm events.

  9. Size- and density-distributions and sources of polycyclic aromatic hydrocarbons in urban road dust.

    Science.gov (United States)

    Murakami, Michio; Nakajima, Fumiyuki; Furumai, Hiroaki

    2005-11-01

    Polycyclic aromatic hydrocarbons (PAHs) present in size- and density-fractionated road dust were measured to identify the important fractions in urban runoff and to analyse their sources. Road dust was collected from a residential area (Shakujii) and a heavy traffic area (Hongo Street). The sampling of road dust from the residential area was conducted twice in different seasons (autumn and winter). The collected road dust was separated into three or four size-fractions and further fractionated into light (1.7 g/cm3) fractions by using cesium chloride solution. Light particles constituted only 4.0+/-1.4%, 0.69+/-0.03% and 3.4+/-1.0% of the road dust by weight for Shakujii (November), Shakujii (February) and Hongo Street, respectively but contained 28+/-10%, 33+/-3% and 44+/-8% of the total PAHs, respectively. The PAH contents in the light fractions were 1-2 orders of magnitude higher than those in the heavy fractions. In the light fractions, the 12PAH contents in February were significantly higher than the 12PAH contents in November (P0.05). Cluster analysis revealed that there was a significant difference in the PAH profiles between locations rather than between size-fractions, density-fractions and sampling times. Multiple regression analysis indicated that asphalt/pavement was the major source of Shakujii road dust, and that tyre and diesel vehicle exhaust were the major sources of finer and coarser fractions collected from Hongo Street road dust, respectively.

  10. Polycyclic aromatic hydrocarbons in urban street dust and surface soil: comparisons of concentration, profile, and source.

    Science.gov (United States)

    Wang, De-Gao; Yang, Meng; Jia, Hong-Liang; Zhou, Lei; Li, Yi-Fan

    2009-02-01

    Street dust and surface soil samples in urban areas of Dalian, a coastal city in Liaoning Province, China, were collected and analyzed for 25 polycyclic aromatic hydrocarbons (PAHs). The concentrations, distribution, and sources of PAHs in dust and soil were determined. The concentrations of total PAHs in street dust ranged between 1890 and 17,070 ng/g (dry weight), with an average of 7460 ng/g, whereas the concentrations of total PAHs in surface soil varied greatly, from 650 to 28,900 ng/g, with a mean value of 6440 ng/g. Statistical paired t-test confirmed that total PAH concentrations have no significant difference between street dust and surface soil. Mean PAH concentrations in two type samples were much higher at industrial sites than at business/residential or garden sites. PAHs were dominated by higher molecular weight PAH (4- to 6-ring) homologues, which accounted for about 73% and 72% of total PAHs in street dust and surface soil, respectively. Principal component analysis was used in source apportionment of PAHs in dust and soil. Pyrogenic and petrogenic sources contributed 70% and 22.4% of total PAHs in street dusts, and fossil fuel (coal and petroleum) and biomass combustion accounted for 64.4% and 5.6% of total PAHs in pyrogenic sources, respectively. In surface soil, total PAHs were dominated by pyrogenic sources. The diagnostic ratios of benz[a]anthracene/chrysene confirmed that PAHs in street dust and surface soil of a Dalian urban zone might come mostly from the emission of local sources.

  11. Developing Subdomain Allocation Algorithms Based on Spatial and Communicational Constraints to Accelerate Dust Storm Simulation.

    Directory of Open Access Journals (Sweden)

    Zhipeng Gui

    Full Text Available Dust storm has serious disastrous impacts on environment, human health, and assets. The developments and applications of dust storm models have contributed significantly to better understand and predict the distribution, intensity and structure of dust storms. However, dust storm simulation is a data and computing intensive process. To improve the computing performance, high performance computing has been widely adopted by dividing the entire study area into multiple subdomains and allocating each subdomain on different computing nodes in a parallel fashion. Inappropriate allocation may introduce imbalanced task loads and unnecessary communications among computing nodes. Therefore, allocation is a key factor that may impact the efficiency of parallel process. An allocation algorithm is expected to consider the computing cost and communication cost for each computing node to minimize total execution time and reduce overall communication cost for the entire simulation. This research introduces three algorithms to optimize the allocation by considering the spatial and communicational constraints: 1 an Integer Linear Programming (ILP based algorithm from combinational optimization perspective; 2 a K-Means and Kernighan-Lin combined heuristic algorithm (K&K integrating geometric and coordinate-free methods by merging local and global partitioning; 3 an automatic seeded region growing based geometric and local partitioning algorithm (ASRG. The performance and effectiveness of the three algorithms are compared based on different factors. Further, we adopt the K&K algorithm as the demonstrated algorithm for the experiment of dust model simulation with the non-hydrostatic mesoscale model (NMM-dust and compared the performance with the MPI default sequential allocation. The results demonstrate that K&K method significantly improves the simulation performance with better subdomain allocation. This method can also be adopted for other relevant atmospheric

  12. Developing Subdomain Allocation Algorithms Based on Spatial and Communicational Constraints to Accelerate Dust Storm Simulation.

    Science.gov (United States)

    Gui, Zhipeng; Yu, Manzhu; Yang, Chaowei; Jiang, Yunfeng; Chen, Songqing; Xia, Jizhe; Huang, Qunying; Liu, Kai; Li, Zhenlong; Hassan, Mohammed Anowarul; Jin, Baoxuan

    2016-01-01

    Dust storm has serious disastrous impacts on environment, human health, and assets. The developments and applications of dust storm models have contributed significantly to better understand and predict the distribution, intensity and structure of dust storms. However, dust storm simulation is a data and computing intensive process. To improve the computing performance, high performance computing has been widely adopted by dividing the entire study area into multiple subdomains and allocating each subdomain on different computing nodes in a parallel fashion. Inappropriate allocation may introduce imbalanced task loads and unnecessary communications among computing nodes. Therefore, allocation is a key factor that may impact the efficiency of parallel process. An allocation algorithm is expected to consider the computing cost and communication cost for each computing node to minimize total execution time and reduce overall communication cost for the entire simulation. This research introduces three algorithms to optimize the allocation by considering the spatial and communicational constraints: 1) an Integer Linear Programming (ILP) based algorithm from combinational optimization perspective; 2) a K-Means and Kernighan-Lin combined heuristic algorithm (K&K) integrating geometric and coordinate-free methods by merging local and global partitioning; 3) an automatic seeded region growing based geometric and local partitioning algorithm (ASRG). The performance and effectiveness of the three algorithms are compared based on different factors. Further, we adopt the K&K algorithm as the demonstrated algorithm for the experiment of dust model simulation with the non-hydrostatic mesoscale model (NMM-dust) and compared the performance with the MPI default sequential allocation. The results demonstrate that K&K method significantly improves the simulation performance with better subdomain allocation. This method can also be adopted for other relevant atmospheric and numerical

  13. Nearly a Decade of CALIPSO Observations of Asian and Saharan Dust Properties near Source and Transport Regions

    Science.gov (United States)

    Omar, A. H.; Tackett, J. L.; Liu, Z.; Vaughan, M. A.; Trepte, C. R.; Winker, D. M.; Yu, H.

    2015-12-01

    The lidar on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, makes robust measurements of dust and has generated a length of record that is significant both seasonally and inter-annually. We exploit this record to determine a multi-year climatology of the properties of Asian and Saharan dust, in particular seasonal optical depths, layer frequencies, and layer heights of dust gridded in accordance with the Level 3 data products protocol between 2006 and 2015. The data are screened using standard CALIPSO quality assurance flags, cloud aerosol discrimination (CAD) scores, overlying features and layer properties. To evaluate the effects of transport on small-scale phenomena such as morphology, vertical extent and size of the dust layers, we compare probability distribution functions of the layer integrated volume depolarization ratios, geometric depths and integrated attenuated color ratios near the source to the same distributions in the far field or transport region. CALIPSO is collaboration between NASA and Centre National d'Études Spatiales (CNES), was launched in April 2006 to provide vertically resolved measurements of cloud and aerosol distributions. The primary instrument on the CALIPSO satellite is the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), a near-nadir viewing two-wavelength polarization-sensitive instrument. The unique nature of CALIOP measurements make it quite challenging to validate backscatter profiles, aerosol type, and cloud phase, all of which are used to retrieve extinction and optical depth. To evaluate the uncertainty in the lidar ratios, we compare the values computed from dust layers overlying opaque water clouds, considered nominal, with the constant lidar ratio value used in the CALIOP algorithms for dust. We also explore the effects of noise on the CALIOP retrievals at daytime by comparing the distributions of the properties at daytime to the nighttime distributions.

  14. Analysis of the spatial distribution of stars, gas and dust in nearby galaxies

    Science.gov (United States)

    Muñoz-Mateos, J. C.

    2013-05-01

    I summarize the main result of my thesis, which was awarded the Spanish Astronomical Society Award for the best thesis in Astronomy defended in 2010. This thesis was supervised by Armando Gil de Paz and Jaime Zamorano at Universidad Complutense de Madrid. In this work we quantified how the physical properties of stars, gas and dust vary with radius in nearby galactic disks, and used that information to infer the past assembly and evolution of galaxies. To do so we made use of spatially-resolved multi-wavelength images of nearby galaxies, all the way from the far-UV to the far-IR and radio. By comparing extinction- corrected profiles in the UV, optical and IR with models of disk evolution, we concluded that the current stellar population gradients are consistent with an inside-out growth of disks of ˜ 25% since z ˜ 1. We also found that the dust-to-gas ratio decreases with radius, and is tightly correlated with the local gas metallicity, which is again consistent with an inside-out assembly of disks. We measured the fraction of the dust mass which is in the form of PAHs at different radii. The resulting trend agrees with certain models of dust evolution, in which the abundance of PAHs is primarily determined by a delayed injection of carbon into the ISM by AGB stars.

  15. Magnetic characteristics of industrial dust from different sources of emission: A case study of Poland

    Science.gov (United States)

    Szuszkiewicz, Marcin; Magiera, Tadeusz; Kapička, Aleš; Petrovský, Eduard; Grison, Hanna; Gołuchowska, Beata

    2015-05-01

    Dust emission and deposition in topsoil have negative effect on individual components of the ecosystem. In addition to routine geochemical analyses, magnetic measurements may provide useful complementary information related to the type, concentration and grain-size distribution of the technogenic magnetic particles (TMPs) and thus the degree of contamination of the environment. The aim of this contribution is to use magnetic parameters in distinguishing dust from a wide range of sources of air pollution (power industry, cement, coke, ceramic industries and biomass combustion). We measured magnetic susceptibility, hysteresis parameters and thermomagnetic curves. Our results suggest that predominant component in tested samples is magnetite, only dust from coking plant and the combustion of lignite contained also maghemite and/or hematite. Mixture of sizes, ranging from fine single-domain to coarse multi-domain grains, was detected. Our results indicate that industrial dusts from various sources of emissions have different specific magnetic properties and magnetic measurements may provide very helpful information.

  16. Insights into the content and spatial distribution of dust from the integrated spectral properties of galaxies

    CERN Document Server

    Chevallard, Jacopo; Wandelt, Benjamin; Wild, Vivienne

    2013-01-01

    [Abridged] We present a new approach to investigate the content and spatial distribution of dust in structurally unresolved star-forming galaxies from the observed dependence of integrated spectral properties on galaxy inclination. We develop an innovative combination of generic models of radiative transfer (RT) in dusty media with a prescription for the spectral evolution of galaxies, via the association of different geometric components of galaxies with stars in different age ranges. We show that a wide range of RT models all predict a quasi-universal relation between slope of the attenuation curve at any wavelength and V-band attenuation optical depth in the diffuse interstellar medium (ISM), at all galaxy inclinations. This relation predicts steeper (shallower) dust attenuation curves than both the Calzetti and MW curves at small (large) attenuation optical depths, which implies that geometry and orientation effects have a stronger influence on the shape of the attenuation curve than changes in the optica...

  17. An Israeli haboob: Sea breeze activating local anthropogenic dust sources in the Negev loess

    Science.gov (United States)

    Crouvi, Onn; Dayan, Uri; Amit, Rivka; Enzel, Yehouda

    2017-02-01

    Meso-scale weather systems, such as convective haboobs, are considered to be an important dust generation mechanism. In Israel, however, rather than of meso-scale weather systems, most dust storms are generated by synoptic-scale systems, originating from Sahara and Arabia. Consequently, only distal sources of suspended and deposited dust in Israel are currently reported. Here we report the first detailed study on the merging of synoptic- and meso-scale weather systems leading to a prominent dust outbreak over the Negev, Israel. During the afternoon of May 2nd, 2007, a massive dust storm covered the northern Negev, forming a one kilometer high wall of dust. The haboob was associated with PM10 concentrations of 1000-1500 μg m-3 that advanced at a speed of 10-15 m s-1 and caused temporary closure of local airports. In contrast to most reported haboobs, this one was generated by a sea breeze front acting as a weak cold front enhanced by a cold core cyclone positioned over Libya and Egypt. The sea breeze that brought cold and moist marine air acted as a gravity current with strong surface winds. The sources for the haboob were the loessial soils of the northwestern Negev, especially agricultural fields that were highly disturbed in late spring to early summer. Such surface disturbance is caused by agricultural and/or intensive grazing practices. Our study emphasizes the importance of local dust sources in the Negev and stresses loess recycling as an important process in contemporary dust storms over Israel.

  18. Spatial distribution and Timing of Dust-Induced CO2 Drawdown during the Last Termination

    Science.gov (United States)

    Lambert, Fabrice; Ridgwell, Andy; Kohfeld, Karen; Winckler, Gisela; Lamy, Frank; Shaffer, Gary; Opazo, Natalia

    2017-04-01

    Mineral dust aerosols in the atmosphere are thought to impact on Earth's climate system directly by absorbing and scattering electromagnetic radiation, and indirectly by acting as cloud nuclei and by influencing biogeochemical cycles through micronutrient fertilization of the biosphere. Iron fertilization of the world's High Nutrient Low Chlorophyl (HNLC) oceanic regions through increased dust deposition during glacial times has been linked to the lower atmospheric pCO2 levels during the Last Glacial Maximum (LGM), 21 ka ago. According to the latest estimates, of the 80-100 ppm difference in atmospheric CO2 concentration between average Holocene and LGM climates, about 40 are due to ocean stratification, 20 to iron fertilization, and 30 to other effects like ocean salinity and temperature, terrestrial biomass, etc. Using a biogeochemistry EMIC with focus on the carbon cycle, we estimate the contribution of the main global dust sources (North and South America, Oceania, Central and East Asia, Sahara, South Africa) to the total iron fertilization effect. We also determine the timing of each region's dust contribution during the last glacial termination.

  19. Polybrominated diphenyl ethers (PBDEs) in the indoor dust in China: levels, spatial distribution and human exposure.

    Science.gov (United States)

    Zhu, Ning-Zheng; Liu, Li-Yan; Ma, Wan-Li; Li, Wen-Long; Song, Wei-Wei; Qi, Hong; Li, Yi-Fan

    2015-01-01

    Indoor environment is an important source of human exposure to several toxicants, such as brominated flame retardants. Indoor dust samples were collected in winter season in 2010, which covered 23 provinces across China, for the analysis of polybrominated diphenyl ethers (PBDEs). Concentrations of PBDEs (Σ14PBDEs) ranged from 8.92 to 37,500 ng/g, with the mean of 3520 ng/g. BDE-209 was the most dominate congener, followed by BDE-183, BDE-47 and BDE-99. PBDE concentrations and the longitude were significantly correlated (pPBDEs through dust ingestion and dermal absorption indicated that the toddlers had the highest exposure dose, with the median value of 6.0 ng/kg-bw/day. According to the hazard quotients, health risk of PBDEs via dust ingestion in China is currently acceptable. Monte Carlo simulation was implemented to quantify the uncertainty and sensitivity of exposure models for determining the most influential variables. The results suggested that more specific and accurate parameters should be used for dust ingestion and dermal absorption exposure models in future.

  20. Spatial distribution and temporal variability of Harmattan dust haze in sub-Sahel West Africa

    Science.gov (United States)

    Anuforom, Anthony C.

    The distributions of frequency of occurrence (FOO) of 'thick dust haze' (TDH) and of 'light dust haze' (LDH) with respect to latitude, longitude, elevation and distance from source during Harmattan season (from November to February) are investigated, using 30-year visibility data collected from 27 synoptic stations located in Nigeria between the West African Sahel and the coasts of Gulf of Guinea. This region lies along the Harmattan season trajectory of Saharan dust. Also investigated is the temporal variability of TDH and LDH on intra-seasonal and inter-annual timescales spanning three decades from 1971 to 2000. Dust haze distribution over the region is found to correlate with the four geographical variables to different extents, with latitude, distance from source and elevation showing strong correlations with both TDH and LDH. The investigation also shows that while FOO of TDH days increases with latitude (correlation coefficient, rlat,FOO_TDH=0.88), FOO of LDH days decreases with latitude over the region (correlation coefficient, rlat,FOO_LDH=-0.74). The correlation coefficients with longitude over the region are rlon,FOO_TDH=0.44 and rlon,FOO_LDH=-0.25, respectively, indicating weaker dependence of TDH and LDH on longitude. The average number of TDH days per month during the Harmattan season in the region ranges from about 0.5 in the humid coastal zone near the Gulf of Guinea in the south, to approximately 6 in the dry semi-arid zone near the West African Sahel. An empirical equation which shows that FOO of TDH increases exponentially with latitude over the region is derived. The FOO of TDH is found to be most variable in or near the Sahel zone and decreases southwards towards the Gulf of Guinea. The average of the standard deviations is 1.13 for the six northernmost synoptic stations and decreases to 0.51 over the six coastal and southernmost locations. In contrast, the FOO of LDH is most variable in the south (with standard deviation of 2.11 (over the six

  1. Development of Briquette from Coir Dust and Rice Husk Blend: An Alternative Energy Source

    Directory of Open Access Journals (Sweden)

    Md. Hamidul Islam

    2014-05-01

    Full Text Available Biomass is one of the predominant renewable energy sources and the use of biomass for the energy generation has got much attention due to its environmental friendliness. Densification of coir dust into fuel briquette can solve waste disposal problem as well as can serve as an alternative energy source. The objective of this study was to investigate the possibility of producing briquette from coir dust and rice husk blend without binder. During this study, a briquetting experiment was conducted with different coir dust and rice husk blends (i.e. coir dust and rice husk ratio of 80:20, 60:40, 50:50, 40:60, 20:80 and 0:100. Briquetting operation was performed using a die-screw press type briquetting machine. The briquettes were tested to evaluate their density, compressive strength, calorific value, burning rate and water vaporizing capacity and it was found that mixing ratio had a significant effect on the physical, mechanical and combustion properties of the coir dust-rice husk briquettes. Density, compressive strength and calorific value and water vaporizing capacity were increased with increasing mixing ratio while burning rate was decreased. Coir dust-rice husk briquettes with mixing ratio of 20:80 had higher density (1.413 g/cm3, compressive strength (218.4 N/cm2, calorific value (4879 kcal/kg, water vaporizing capacity (0.853 l/kg and low burning rate (0.783 kg/hour followed by the mixing ratio 40:60, 50:50, 60:40 and 0:100. The results indicate that coir dust and rice husk blend briquettes were found to have better overall handling characteristics over rice husk briquette. However, production of briquettes from coir dust and rice husk at mixing ratio of 50:50 was found to be more suitable for commercial application in terms of cost effectiveness.

  2. Present and Past Impact of Glacially Sourced Dust on Iron Fertilization of the Southern Ocean

    Science.gov (United States)

    Shoenfelt, E. M.; Winckler, G.; Kaplan, M. R.; Sambrotto, R.; Bostick, B. C.

    2016-12-01

    An increase in iron-containing dust flux and a more efficient biological pump in the Southern Ocean have been associated with the CO2 drawdown and global cooling of the Last Glacial Maximum (LGM). While iron (Fe) mineralogy is known to affect Fe bioavailability through its impact on Fe solubility, there are limited studies investigating the importance of Fe mineralogy in dust fluxes to the Southern Ocean, and no previous studies investigating interactions between eukaryotic phytoplankton and particulate-phase Fe in natural dusts applicable to Southern Ocean environments. Since physically weathered bedrock becomes less soluble as it becomes weathered and oxidized, we hypothesized that glacially sourced dusts would contain more Fe(II)-rich primary minerals and would be more bioavailable than dusts from areas not impacted by glaciers. We used a series of natural dusts from Patagonia as the sole Fe source in incubation experiments with the model diatom Phaeodactylum tricornutum, and evaluated Fe bioavailability using culture growth rates, cell density, and variable fluorescence. Monod curves were also used to evaluate the efficiency of the different particulates as sources of nutrient Fe. Using these Monod curves fit to growth rates plotted against particulate Fe concentrations, we observed that 1) Fe(II)-rich primary silicates were significantly more effective as an Fe source to diatoms than Fe(III)-rich oxides, that 2) Fe(II) content itself was responsible for the difference in Fe bioavailability/efficiency of the Fe nutrient source, and that 3) surface interactions with the particulates were important. In an effort to explore the possibility that Fe mineralogy impacted Fe bioavailability in past oceans, we will present our hypotheses regarding productivity and Fe mineralogy/bioavailability through the last glacial cycle.

  3. Regional prediction of carbon isotopes in soil carbonates for Asian dust source tracer

    Science.gov (United States)

    Chen, Bing; Cui, Xinjuan; Wang, Yaqiang

    2016-10-01

    Dust particles emitted from deserts and semi-arid lands in northern China cause particulate pollution that increases the burden of disease particularly for urban population in East Asia. The stable carbon isotopes (δ13C) of carbonates in soils and dust aerosols in northern China were investigated. We found that the δ13C of carbonates in surface soils in northern China showed clearly the negative correlation (R2 = 0.73) with Normalized Difference Vegetation Index (NDVI). Using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived NDVI, we predicted the regional distribution of δ13C of soil carbonates in deserts, sandy lands, and steppe areas. The predictions show the mean δ13C of -0.4 ± 0.7‰ in soil carbonates in Taklimakan Desert and Gobi Deserts, and the isotope values decrease to -3.3 ± 1.1‰ in sandy lands. The increase in vegetation coverage depletes 13C in soil carbonates, thus the steppe areas are predicted by the lowest δ13C levels (-8.1 ± 1.7‰). The measurements of atmospheric dust samples at eight sites showed that the Asian dust sources were well assigned by the 13C mapping in surface soils. Predicting 13C in large geographical areas with fine resolution offers a cost-effective tracer to monitor dust emissions from sandy lands and steppe areas which show an increasing role in Asian dust loading driven by climate change and human activities.

  4. Spatial and temporal variabilities of spring Asian dust events and their impacts on chlorophyll-a concentrations in the western North Pacific Ocean

    Science.gov (United States)

    Yoon, Joo-Eun; Kim, Kitae; Macdonald, Alison M.; Park, Ki-Tae; Kim, Hyun-Cheol; Yoo, Kyu-Cheul; Yoon, Ho-Il; Yang, Eun Jin; Jung, Jinyoung; Lim, Jae-Hyun; Kim, Ju-Hyoung; Lee, Jiyoung; Choi, Tae-Jun; Song, Jae-Min; Kim, Il-Nam

    2017-02-01

    As the western North Pacific Ocean is located downwind of the source regions for spring Asian dust, it is an ideal location for determining the response of open waters to these events. Spatial analysis of spring Asian dust events from source regions to the western North Pacific, using long-term daily aerosol index data, revealed three different transport pathways supported by the westerly wind system: one passing across the northern East/Japan Sea (40°N-50°N), a second moving over the entire East/Japan Sea (35°N-55°N), and a third flowing predominantly over the Siberian continent (>50°N). Our results indicate that strong spring Asian dust events can increase ocean primary productivity by more than 70% (>2-fold increase in chlorophyll-a concentrations) compared to weak/nondust conditions. Therefore, attention should be paid to the recent downturn in the number of spring Asian dust events and to the response of primary production in the western North Pacific to this change.

  5. Modeling of particulate matter transport in atmospheric boundary layer following dust emission from source areas

    Science.gov (United States)

    Katra, Itzhak; Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris; Yizhaq, Hezi

    2016-03-01

    A two-dimensional model for particulate matter (PM) dispersion due to dust emission from soils is presented. Field experiments were performed at a dust source site (Negev loess soil) with a portable boundary layer wind tunnel to determine the emitted PM fluxes for different wind speeds and varying soil conditions. The numerical model is formulated using parameterizations based on the aeolian experiments. The wind velocity profiles used in the simulations were fitted from data obtained in field measurements. Size distribution of the emitted dust particles in the numerical simulations was taken into account using a Monte Carlo method. The PM concentration distributions at a distance of several kilometers from the dust source under specific shear velocities and PM fluxes from the soil were determined numerically by solving advection-diffusion equation. The obtained PM10 concentrations under typical wind and soil conditions are supported by PM data recorded over time in a standard environmental monitoring station. The model enhances our capacity of quantification of dust processes to support climate models as well as health risk assessment.

  6. Sources and distribution of polycyclic aromatic hydrocarbons in street dust from the Chang-Zhu-Tan Region, Hunan, China.

    Science.gov (United States)

    Long, Yongzhen; Dai, Tagen; Wu, Qianhong

    2013-02-01

    Street dusts collected from 20 locations in the Chang-Zhu-Tan (Changsha, Zhuzhou, and Xiangtan) region, Hunan, China, in May to July 2006, were investigated for sources of polycylic aromatic hydrocarbons (PAHs). The individual PAH concentrations were in the range of 10-4316 ng g(-1), and ∑PAHs(16) levels were in the range of 3,515-24,488 ng g(-1), with a mean of 8,760 ng g(-1). The high-molecular-weight PAHs (four to six rings), ranging from 47.51 to 82.11 %, with a mean of 74.79 %, were the dominant PAH compounds in almost all of the dusts. The isomer ratios suggested a rather uniform mixture of coal combustion and petroleum PAH sources. Factor analysis and multiple linear regression analysis indicate that the main sources of the 16 PAHs were coal combustion/vehicle exhaust, coking/petroleum, and plant combustion, with contribution rates of 50.9, 35.01, and 14.08, respectively. The spatial distributions of PAH concentrations were significantly related to the distribution of industries, traffic circulation, and farmland in this region.

  7. Global Scale Attribution of Anthropogenic and Natural Dust Sources and their Emission Rates Based on MODIS Deep Blue Aerosol Products

    Science.gov (United States)

    Ginoux, Paul; Prospero, Joseph M.; Gill, Thomas E.; Hsu, N. Christina; Zhao, Ming

    2012-01-01

    Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Here we present a global-scale high-resolution (0.1 deg) mapping of sources based on Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue estimates of dust optical depth in conjunction with other data sets including land use. We ascribe dust sources to natural and anthropogenic (primarily agricultural) origins, calculate their respective contributions to emissions, and extensively compare these products against literature. Natural dust sources globally account for 75% of emissions; anthropogenic sources account for 25%. North Africa accounts for 55% of global dust emissions with only 8% being anthropogenic, mostly from the Sahel. Elsewhere, anthropogenic dust emissions can be much higher (75% in Australia). Hydrologic dust sources (e.g., ephemeral water bodies) account for 31% worldwide; 15% of them are natural while 85% are anthropogenic. Globally, 20% of emissions are from vegetated surfaces, primarily desert shrublands and agricultural lands. Since anthropogenic dust sources are associated with land use and ephemeral water bodies, both in turn linked to the hydrological cycle, their emissions are affected by climate variability. Such changes in dust emissions can impact climate, air quality, and human health. Improved dust emission estimates will require a better mapping of threshold wind velocities, vegetation dynamics, and surface conditions (soil moisture and land use) especially in the sensitive regions identified here, as well as improved ability to address small-scale convective processes producing dust via cold pool (haboob) events frequent in monsoon regimes.

  8. Mineralogical analysis of attic dust samples for contamination source identification in an industrial area, Ajka, Hungary

    Science.gov (United States)

    Völgyesi, Péter; Jordan, Gyozo; Gosar, Mateja; Szabó, Csaba; Miler, Miloš; Kónya, Péter; Bartha, András

    2013-04-01

    The post-war centrally directed economy forced massive heavy industry in Hungary, producing huge amount of wastes and pollution. Long-term airborne emissions from mining, coal-fired power plants and alumina industry have left the legacy of widely distributed contamination around industrial areas and nearby settlements in the Ajka region. Recent research suggests that significant amount of airborne pollutants, deposited in the urban environment, can be efficiently studied by attic dust analysis. The sampling strategy followed a grid-based stratified random sampling design and 30 samples were collected in 27 houses (at least 30 years old) in a 8x8 grid of the 64 km2 project area. In order to determine the pollution potential of attic dust samples, geochemical and mineralogical analyses were performed. The main aim of the mineralogical analyses was to study the phase composition of the dust particles and to identify potential anthropogenic sources. The total concentrations of the toxic elements (As, Pb, Cd, Cu, Ni and Zn) were measured with ICP-OES and mercury content was analyzed with atomic absorption spectrometry. Phase analyses of the samples were carried out by the means of scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X-Ray diffraction (XRD) methods. Laser particle size analyzer was used to measure the grain size of attic dust particles. Results showed that the studied attic dust in the Ajka urban area was contaminated mostly by Hg, Pb and Zn with contents ranging between 0.1-2 ppm, 42.5-881 ppm and 90.2-954 ppm, respectively. However, the study of extreme data values (statistical outliers) has shown that at certain points airborne dust can be extremely contaminated also with Cd (0.4-11.7 ppm). The size of the attic dust particles varied between 0.2 and 113 µm. Based on the SEM/EDS and XRD analysis, the most frequently identified mineralogical phases were quartz, calcite, gypsum and Fe- and Al-bearing phases. Fe

  9. Dusts, scale, slags, sludges... Not wastes, but sources of profits

    Science.gov (United States)

    Koros, Peter J.

    2003-12-01

    Historically, the steel industry has focused on the need for and the many benefits of recycling steel that is discarded either in its own or in its customers’ manufacturing processes, as well as in recovery and reuse of steel scrap that arises after the product has served its intended purpose. In fact, modern steelmaking relies on the use of recycled iron units for at least half of its production. The other side of the story is the fate of the non-steel by-products (e.g., oxide dusts, sludges, scales, slags, spent refractories and the contained “low grade” energy units that are generated as natural adjuncts to iron and steelmaking processes). These valuable by-products often are classified as “wastes” and are discarded to landfills, at significant cost, although in reality they offer significant potential for cost savings or profit if reintroduced into the industrial arena via well planned programs. Examples of such instances will be presented, including energy credit issues, in the hope of pointing the way for future expansion of benefits from these opportunities. Preparing for a challenge and honor such as the Howe Memorial Lecture, one has to stand in awe of the accomplishments of the predecessor we honor in this forum. He worked in the early days of our industry without the benefits of the many technological improvements he and his successors brought to play as the years went by. John Stubbles, in his Howe Memorial Lecture in 1997,[1] presented a masterful and entertaining biography of Howe and his very active and prolific life. Perhaps the most telling quotation he attributed to Howe is very pertinent to the topic we will address presently: “Metallurgy lives by profit, not logic,” to which I would like to add a comment that bears on the topic of this lecture from the 1991 Howe lecturer, my friend and mentor Bill Dennis, “Where there is muck, there is money.” There are numerous examples of “one hand washes the other” in this business; that

  10. Spatially-resolved dust properties of the GRB 980425 host galaxy

    CERN Document Server

    Michałowski, Michał J; Palazzi, E; Savaglio, S; Gentile, G; Rasmussen, J; Baes, M; Basa, S; Bianchi, S; Berta, S; Burlon, D; Ceron, J M Castro; Covino, S; Cuby, J -G; D'Elia, V; Ferrero, P; Gotz, D; Hjorth, J; Koprowski, M P; Borgne, D Le; Floc'h, E Le; Malesani, D; Murphy, T; Pian, E; Piranomonte, S; Rossi, A; Sollerman, J; Tanvir, N R; Postigo, A de Ugarte; Watson, D; van der Werf, P; Vergani, S D; Xu, D

    2013-01-01

    Gamma-ray bursts (GRBs) have been proposed as a tool to study star formation in the Universe, so it is crucial to investigate whether their host galaxies and immediate environments are in any way special compared with other star-forming galaxies. Here we present spatially resolved maps of dust emission of the host galaxy of the closest known GRB 980425 at z=0.0085 using our new high-resolution observations from Herschel, APEX, ALMA and ATCA. We modeled the spectral energy distributions of the host and of the star-forming region displaying the Wolf-Rayet signatures in the spectrum (WR region), located 800 pc away from the GRB position. The host is characterised by low dust content and high fraction of UV-visible star-formation, similar to other dwarf galaxies. Such galaxies are abundant in the local universe, so it is not surprising to find a GRB in one of them, assuming the correspondence between the GRB rate and star-formation. The WR region contributes substantially to the host emission at the far-infrared,...

  11. Quantifying atmospheric processing of mineral dust as a source of bioavailable phosphorus to the open oceans

    Science.gov (United States)

    Herbert, Ross; Stockdale, Anthony; Carslaw, Ken; Krom, Michael

    2016-04-01

    The transport and deposition of mineral dust is known to be the dominant source of phosphorus (P) to the surface waters of the open oceans. However, the fraction of this P that is deemed available for primary productivity remains a key uncertainty due to a limited understanding of the processes occurring during transport of the dust. Through a series of detailed laboratory experiments using desert dust and dust precursors, we show that the dissolution behaviour of P in these samples is controlled by a surface-bound labile pool, and an additional mineral pool primarily consisting of apatite. The acid dissolution of the apatite occurs rapidly and is controlled by the absolute number of H+ ions present in the solution surrounding the dust. Using these results we develop a new conceptual model that reproduces the major processes controlling P dissolution in the atmosphere. We then use a global aerosol microphysics model with a global soil database to quantify the deposition of bioavailable P to the open oceans and ice sheets. We show that, globally, the labile pool contributes 2.4 Gg P a-1 to the oceans and, from a potential pool of 11.5 Gg P a-1, the dissolved apatite pool contributes 0.24 Gg P a-1. A series of sensitivity studies identifying sources of acid in the atmosphere show that anthropogenic emissions of SO2 contribute 61% of the global mass of dissolved apatite, volcanic events contribute 11%, and DMS emissions contribute 10%. Finally, we show that the fraction of mineral dust P that is available for primary productivity varies, regionally, from 50% in the South Pacific Ocean; this explains the variability in the fraction of bioavailable P commonly observed in important oceanic regions.

  12. Fresnel spatial filtering of quasihomogeneous sources for wave optics simulations

    Science.gov (United States)

    Hyde, Milo W.; Bose-Pillai, Santasri R.

    2017-08-01

    High-spatial-frequency optical fields or sources are often encountered when simulating directed energy, active imaging, or remote sensing systems and scenarios. These spatially broadband fields are a challenge in wave optics simulations because the sampling required to represent and then propagate these fields without aliasing is often impractical. To address this, two spatial filtering techniques are presented. The first, called Fresnel spatial filtering, finds a spatially band-limited source that, after propagation, produces the exact observation plane field as the broadband source over a user-specified region of interest. The second, called statistical or quasihomogeneous spatial filtering, finds a spatially band-limited source that, after propagation and over a specified region of interest, yields an observation plane field that is statistically representative of that produced by the original broadband source. The pros and cons of both approaches are discussed in detail. A wave optics simulation of light transiting a ground glass diffuser and then propagating to an observation plane in the near-zone is performed to validate the two filtering approaches.

  13. Perceived loudness of spatially distributed sound sources

    DEFF Research Database (Denmark)

    Song, Woo-keun; Ellermeier, Wolfgang; Minnaar, Pauli

    2005-01-01

    of a microphone (monaural) and a dummy head (binaural) placed at the listening position. The results show that while loudness metrics fared well in predicting perceived loudness for any single-sound condition, they failed to predict loudness for two simultaneous sounds. This suggests that current loudness......In noise-control engineering, one is often faced with the task of identifying the most problematic of several simultaneous sound sources. Traditionally, this has been done by deriving sound pressure (or intensity) maps by means of a microphone array. This approach does not, however, take...... psychoacoustic attributes into account. Therefore, a method for deriving loudness maps was developed in an earlier study [Song, Internoise2004, paper 271]. The present experiment investigates to which extent perceived loudness depends on the distribution of individual sound sources. Three loudspeakers were...

  14. Source identification and health risk assessment of metals in indoor dust in the vicinity of phosphorus mining, Guizhou Province, China.

    Science.gov (United States)

    Yang, Qin; Chen, Huaguo; Li, Baizhan

    2015-01-01

    An investigation was performed to identify the sources of arsenic (As) and heavy metals in house dust and to assess the associated human health risks in the vicinity of phosphorus (P) mining in Guizhou, China. The concentrations and spatial distributions of mercury (Hg), As, cadmium (Cd), lead (Pb), iron (Fe), copper (Cu), manganese (Mn), and P in 23 house dust samples from the study area were determined. Greater concentrations of As and Pb were found compared with values in other investigations in various countries. Pollution sources were identified using multivariate statistical analysis. As, Pb, Mn, and Hg pollution was mainly attributed to mining activities, and Mn and Cd levels were largely associated with automobile emissions. The dominant wind direction and the distance of the residence from the mining region were found to play an important role in element distributions. A health risk assessment showed that As and Pb should be paid more attention, although the noncancer risks of the studied elements were within the safe range and the cancer risks of As and Cd are within the acceptable range under present conditions.

  15. Source identification of heavy metals in atmospheric dust using Platanus orientalis L. leaves as bioindicator

    Directory of Open Access Journals (Sweden)

    Samira Norouzi

    2015-07-01

    Full Text Available Studies on atmospheric dust have been limited by the high cost of instrumental monitoring methods and also sampling difficulties. The use of organisms acting as bioaccumulators has recently been proposed. In this study, the leaves of Platanus orientalis L., as a possible biomonitor of heavy metals in atmospheric dust, were evaluated to understand the likely source(s of pollution in Isfahan, Iran. Concentration of Zn, Cu, Ni and Mn and Magnetic susceptibility (χlf were determined in washed (WL and unwashed leaves (UL, monthly sampled from May to Nov., 2012. By subtracting the amount of metal concentrations and χlf in UL and WL, the amount of these parameters in dust deposited on the leaves (UL-WL were calculated. Enrichment factor analysis (EF, correlation coeficient, principal component analysis (PCA and cluster analysis (CA on the UL-WL data were employed to trace the heavy metals sources. Results showed that the metal concentration in UL and WL in primary sampling times was not statistically different. As time passed, this difference became more noticeable. Seasonal accumulation trends of elements concentration in UL-WL, referred to as accumulative biomonitors showing the accumulation of dust on the leaves are considerable and the contamination of plants by metal occurs mainly by retention of particulate matter. All the heavy metals are well correlated with χlf, indicating the potential of magnetic measurement as an inexpensive and less laborious method to estimate heavy metals. Cu and Zn exhibited a very strong correlation with each other and the highest correlation with χlf, suggesting an anthropogenic nature of these two metals. High EF of Cu and Zn showed that anthropogenic sources contribute a substantial amount of these metals to dust deposited on leaves. Whereas, less EF for Mn and Ni shows that natural source and local polluted soils might be the main origins of these metals. PCA results showed 2 principal components. Factor 1 with

  16. Blind separation of incoherent and spatially disjoint sound sources

    Science.gov (United States)

    Dong, Bin; Antoni, Jérôme; Pereira, Antonio; Kellermann, Walter

    2016-11-01

    Blind separation of sound sources aims at reconstructing the individual sources which contribute to the overall radiation of an acoustical field. The challenge is to reach this goal using distant measurements when all sources are operating concurrently. The working assumption is usually that the sources of interest are incoherent - i.e. statistically orthogonal - so that their separation can be approached by decorrelating a set of simultaneous measurements, which amounts to diagonalizing the cross-spectral matrix. Principal Component Analysis (PCA) is traditionally used to this end. This paper reports two new findings in this context. First, a sufficient condition is established under which "virtual" sources returned by PCA coincide with true sources; it stipulates that the sources of interest should be not only incoherent but also spatially orthogonal. A particular case of this instance is met by spatially disjoint sources - i.e. with non-overlapping support sets. Second, based on this finding, a criterion that enforces both statistical and spatial orthogonality is proposed to blindly separate incoherent sound sources which radiate from disjoint domains. This criterion can be easily incorporated into acoustic imaging algorithms such as beamforming or acoustical holography to identify sound sources of different origins. The proposed methodology is validated on laboratory experiments. In particular, the separation of aeroacoustic sources is demonstrated in a wind tunnel.

  17. Source apportionment of arsenic in atmospheric dust fall out in an urban residential area, Raipur, Central India

    Directory of Open Access Journals (Sweden)

    G. Balakrishna

    2011-06-01

    Full Text Available The components and quantities of atmospheric dust fallout have been reported to be the pollution indicator of large urban areas. The multiplicity and complexity of sources of atmospheric dusts in urban regions has put forward the need of source apportionment of these sources indicating their contribution to specific environmental receptor. The study presented here is focused on investigation of source contribution estimates of Arsenic in urban dust fallout in an urban-industrial area, Raipur, India. Source-receptor based representative sampling plan using longitudinal study design has been adopted. Six sampling sites have been identified on the basis of land use for development plan of anthropogenic activities and factors related to the transportation and dispersion pattern of atmospheric dusts. Source apportionment has been done using Chemical Mass Balance (CMB 8. Good fit parameters and relative source contribution has been analyzed and documented. Dominance of coal fired industries sources on arsenic levels measured at selected ambient residential receptors compared to line sources has been observed. Road-traffic has shown highest contribution of dust at indoor houses and out door-street automobile exhaust has shows highest contribution for arsenic. The results of CMB output and regression data of source-receptor dust matrices have shown comparable pattern.

  18. Distribution, sources and health risk assessment of mercury in kindergarten dust

    Science.gov (United States)

    Sun, Guangyi; Li, Zhonggen; Bi, Xiangyang; Chen, Yupeng; Lu, Shuangfang; Yuan, Xin

    2013-07-01

    Mercury (Hg) contamination in urban area is a hot issue in environmental research. In this study, the distribution, sources and health risk of Hg in dust from 69 kindergartens in Wuhan, China, were investigated. In comparison with most other cities, the concentrations of total mercury (THg) and methylmercury (MeHg) were significantly elevated, ranging from 0.15 to 10.59 mg kg-1 and from 0.64 to 3.88 μg kg-1, respectively. Among the five different urban areas, the educational area had the highest concentrations of THg and MeHg. The GIS mapping was used to identify the hot-spot areas and assess the potential pollution sources of Hg. The emissions of coal-power plants and coking plants were the main sources of THg in the dust, whereas the contributions of municipal solid waste (MSW) landfills and iron and steel smelting related industries were not significant. However, the emission of MSW landfills was considered to be an important source of MeHg in the studied area. The result of health risk assessment indicated that there was a high adverse health effect of the kindergarten dust in terms of Hg contamination on the children living in the educational area (Hazard index (HI) = 6.89).

  19. Study of Arabian Red Sea coastal soils as potential mineral dust sources

    KAUST Repository

    Prakash, P. Jish

    2016-03-23

    Both Moderate Resolution Imaging Spectroradiometer (MODIS) and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) satellite observations suggest that the narrow heterogeneous Red Sea coastal region is a frequent source of airborne dust that, because of its proximity, directly affects the Red Sea and coastal urban centers. The potential of soils to be suspended as airborne mineral dust depends largely on soil texture, moisture content, and particle size distributions. Airborne dust inevitably carries the mineralogical and chemical signature of a parent soil. The existing soil databases are too coarse to resolve the small but important coastal region. The purpose of this study is to better characterize the mineralogical, chemical and physical properties of soils from the Red Sea Arabian coastal plane, which in turn will help to improve assessment of dust effect on the Red Sea and land environmental systems and urban centers. Thirteen surface soils from the hot-spot areas of wind-blown mineral dust along the Red Sea coastal plain were sampled for analysis. Analytical methods included Optical Microscopy, X-ray diffraction (XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Ion Chromatography (IC), Scanning Electron Microscopy (SEM), and Laser Particle Size Analysis (LPSA). We found that the Red Sea coastal soils contain major components of quartz and feldspar, as well as lesser but variable amounts of amphibole, pyroxene, carbonate, clays, and micas, with traces of gypsum, halite, chlorite, epidote and oxides. The wide range of minerals in the soil samples was ascribed to the variety of igneous and metamorphic provenance rocks of the Arabian Shield forming the escarpment to the east of the Red Sea coastal plain. The analysis revealed that the samples contain compounds of nitrogen, phosphorus and iron that are essential nutrients to marine life. The analytical results from this study will provide a valuable input into dust emission models used

  20. Long-Term Variations, Signatures, Sources of Asian Dust and Role of Climate Change Versus Desertification in Asian Dust Emission

    Institute of Scientific and Technical Information of China (English)

    X.Y. Zhang; S.L. Gong; T.L. Zhao; R. Arimoto; Y.Q. Wang; Z.J. Zhou

    2004-01-01

    @@ For long-term variations and elemental signatures of Asian dust aerosol, changes in mass, twenty elemental concentrations over the period 2001~2003 were assessed from five surface-based stations in western, northern, northeast deserts, the Loess Plateau and the coastal areas in China. Together with the back trajectory analyses and visibility observations, the elemental signatures of soil dust aerosol from different air-mass clusters were characterized for the dust storm (DS) and non-dust storm (N-DS)conditions, respectively.

  1. Sedimentary and mineral dust sources of dissolved iron to the World Ocean

    Directory of Open Access Journals (Sweden)

    J. K. Moore

    2007-04-01

    Full Text Available A worldwide database of dissolved iron observations is used to improve simulations of the marine iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC ocean model. Modifications to the model include: 1 an improved particle scavenging parameterization based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2 desorption of dissolved iron from sinking particles; and 3 an improved sedimentary source for dissolved iron. Most scavenged iron (90% is put on sinking particles to remineralize deeper in the water column. The model-observation mismatches are greatly reduced both in surface waters and in the deeper ocean. Inclusion of desorption has little effect on surface water iron concentrations where adsorption/scavenging is strongly dominant, but significantly increases simulated iron concentrations in the deep ocean. Our results suggest that there must be substantial removal of dissolved iron from subsurface waters (where iron concentrations are <0.6 nM in most regions to match observed distributions. Aggregation and removal on sinking particles of Fe bound to organic colloids is a likely mechanism.

    The improved BEC model is used to address the relative contributions of mineral dust and marine sediments in driving ocean productivity and observed dissolved iron distributions. The sedimentary iron source from the continental margins has a strong impact on open ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in this region allows the continental iron source to be advected far from source areas. Both the margin sediment and mineral dust Fe sources significantly impact global scale primary production, export production, and nitrogen fixation

  2. Physical infeasibility of geodesic dissipative dust as a source of gravitational radiation

    CERN Document Server

    Herrera, L; Ospino, J

    2015-01-01

    Using a framework based on the 1+3 formalism, we show that a source represented by a geodesic, dissipative, rotational dust, endowed with axial and reflection symmetry, violates regularity conditions at the center of the fluid distribution, unless the dissipative flux vanishes. In this latter case the vorticity also must vanish, and the resulting spacetime is Friedman--Robertson--Walker (FRW). Therefore it does not produce gravitational radiation.

  3. Ancient versus modern mineral dust transported to high-altitude alpine glaciers evidences saharan sources and atmospheric circulation changes

    Directory of Open Access Journals (Sweden)

    F. Thevenon

    2011-01-01

    Full Text Available Mineral dust aerosols collected during the years 2008/09 at the high-altitude research station Jungfraujoch (46°33' N, 7°59' E; 3580 m a.s.l. were compared to windblown mineral dust deposited at the Colle Gnifetti glacier (45°55' N, 7°52' E, 4455 m a.s.l. over the last millennium. Insoluble dust has been characterized in terms of mineralogy, Sr and Nd isotopic ratios, and trace element composition. Results demonstrate that the Saharan origin of the airborne dust did not change significantly throughout the past. Backward trajectories analysis of modern analogs furthermore confirms that major dust sources are situated in the north-central to north-western part of the Saharan desert. By contrast, less radiogenic Sr isotopic compositions are associated with lower abundances of crustal elements during low rates of dust deposition, suggesting intercontinental transport of background dust rather than activation of a secondary source. Saharan dust mobilization and meridional advection of air masses were relatively reduced during the second part of the Little Ice Age (ca. 1690–1870, except within the greatest Saharan dust event deposited around 1780–1790. Higher dust deposition with larger mean grain size and Saharan fingerprint began ca. 20 years after the industrial revolution of 1850, suggesting that increased mineral dust transport over the Alps during the last century was primarily due to drier winters in North Africa and stronger spring/summer North Atlantic southwesterlies, rather than to direct anthropogenic sources. Meanwhile, increasing carbonaceous particle emissions from fossil fuels combustion combined to higher lead enrichment factor during the last century, point to concomitant anthropogenic sources of particulate pollutants reaching high-altitude European glaciers.

  4. Coal fly ash as a source of iron in atmospheric dust.

    Science.gov (United States)

    Chen, Haihan; Laskin, Alexander; Baltrusaitis, Jonas; Gorski, Christopher A; Scherer, Michelle M; Grassian, Vicki H

    2012-02-21

    Anthropogenic coal fly ash (FA) aerosol may represent a significant source of bioavailable iron in the open ocean. Few measurements have been made that compare the solubility of atmospheric iron from anthropogenic aerosols and other sources. We report here an investigation of iron dissolution for three FA samples in acidic aqueous solutions and compare the solubilities with that of Arizona test dust (AZTD), a reference material for mineral dust. The effects of pH, simulated cloud processing, and solar radiation on iron solubility have been explored. Similar to previously reported results on mineral dust, iron in aluminosilicate phases provides the predominant component of dissolved iron. Iron solubility of FA is substantially higher than of the crystalline minerals comprising AZTD. Simulated atmospheric processing elevates iron solubility due to significant changes in the morphology of aluminosilicate glass, a dominant material in FA particles. Iron is continuously released into the aqueous solution as FA particles break up into smaller fragments. These results suggest that the assessment of dissolved atmospheric iron deposition fluxes and their effect on the biogeochemistry at the ocean surface should be constrained by the source, environmental pH, iron speciation, and solar radiation.

  5. Anthropogenic Air Pollution Observed Near Dust Source Regions in Northwestern China During Springtime 2008

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Fu, Joshua S.; Dickerson, Russell R.; Ji, Qiang; Bell, Shaun W.; Gao, Yang; Zhang, Wu; Huang, Jianping; Li, Zhanqing; Chen, Hongbin

    2010-01-01

    Trace gases and aerosols were measured in Zhangye (39.082degN, 100.276degE, 1460 m a.s. 1.), a rural site near the Gobi deserts in northwestern China during spring 2008. Primary trace gases (CO:265 ppb; SO2:3.4 ppb; NO(*y): 4.2 ppb; hereafter results given as means of hourly data) in the area were lower than in eastern China, but still indicative of marked anthropogenic emissions. Sizable aerosol mass concentration (153 micro-g/cu m) and light scattering (159/Mm at 500 nm) were largely attributable to dust emissions, and aerosol light absorption (10.3/Mm at 500 nm) was dominated by anthropogenic pollution. Distinct diurnal variations in meteorology and pollution were induced by the local valley terrain. Strong daytime northwest valley wind cleaned out pollution and was replaced by southeast mountain wind that allowed pollutants to build up overnight. In the afternoon, aerosols had single scattering albedo (SSA, 500 mn) of 0.95 and were mainly of supermicron particles, presumably dust, while at night smaller particles and SSA of 0.89-0.91 were related to Pollution. The diverse local emission sources were characterized: the CO/SO2, CO/NO(y), NO(y)/SO2 (by moles), and BC/CO (by mass) ratios for small point sources such as factories were 24.6-54.2, 25.8-35.9, 0.79-1.31, and 4.1-6.1 x 10(exp -3), respectively, compared to the corresponding inventory ratios of 43.7-71.9, 23.7-25.7, 1.84-2.79, and 3.4-4.0 x 10(exp -3) for the industrial sector in the area. The mixing between dust and pollution can be ubiquitous in this region. During a dust storm shown as an example, pollutants were observed to mix with dust, causing discernible changes in both SSA and aerosol size distribution. Further interaction between dust and pollutants during transport may modify the properties of dust particles that are critical for their large-scale impact on radiation, clouds, and global biogeochemical cycles.

  6. Anthropogenic air pollution observed near dust source regions in northwestern China during springtime 2008

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Fu, Joshua S.; Dickerson, Russell R.; Ji, Qiang; Bell, Shaun W.; Gao, Yang; Zhang, Wu; Huang, Jianping; Li, Zhanqing; Chen, Hongbin

    2010-04-01

    Trace gases and aerosols were measured in Zhangye (39.082°N, 100.276°E, 1460 m a.s.l.), a rural site near the Gobi deserts in northwestern China during spring 2008. Primary trace gases (CO: 265 ppb; SO2: 3.4 ppb; NOy*: 4.2 ppb; hereafter results given as means of hourly data) in the area were lower than in eastern China, but still indicative of marked anthropogenic emissions. Sizable aerosol mass concentration (153 μg/m3) and light scattering (159 Mm-1 at 500 nm) were largely attributable to dust emissions, and aerosol light absorption (10.3 Mm-1 at 500 nm) was dominated by anthropogenic pollution. Distinct diurnal variations in meteorology and pollution were induced by the local valley terrain. Strong daytime northwest valley wind cleaned out pollution and was replaced by southeast mountain wind that allowed pollutants to build up overnight. In the afternoon, aerosols had single scattering albedo (SSA, 500 nm) of 0.95 and were mainly of supermicron particles, presumably dust, while at night smaller particles and SSA of 0.89-0.91 were related to pollution. The diverse local emission sources were characterized: the CO/SO2, CO/NOy, NOy/SO2 (by moles), and BC/CO (by mass) ratios for small point sources such as factories were 24.6-54.2, 25.8-35.9, 0.79-1.31, and 4.1-6.1 × 10-3, respectively, compared to the corresponding inventory ratios of 43.7-71.9, 23.7-25.7, 1.84-2.79, and 3.4-4.0 × 10-3 for the industrial sector in the area. The mixing between dust and pollution can be ubiquitous in this region. During a dust storm shown as an example, pollutants were observed to mix with dust, causing discernible changes in both SSA and aerosol size distribution. Further interaction between dust and pollutants during transport may modify the properties of dust particles that are critical for their large-scale impact on radiation, clouds, and global biogeochemical cycles.

  7. Spatial and temporal source apportionment of PM2.5 in Georgia, 2002 to 2013

    Science.gov (United States)

    Zhai, Xinxin; Mulholland, James A.; Russell, Armistead G.; Holmes, Heather A.

    2017-07-01

    The Chemical Mass Balance (CMB) receptor model was applied to estimate PM2.5 source impacts over Georgia from 2002 to 2013 using ambient PM2.5 species concentration data from 13 sites. Measurements of 19 PM2.5 species were used as inputs along with measurement-based source profiles to estimate the impacts of nine sources, including both primary components (from heavy duty diesel vehicle, light duty gasoline vehicle, biomass burning, coal combustion, and suspended dust sources) and secondary pollutants (ammonium sulfate, ammonium bisulfate, ammonium nitrate, and secondary organic carbon). From 2002 to 2013, PM2.5 total mass decreased from 13.8 μg/m3 to 9.2 μg/m3 averaged across all sites, a 33% decrease. Largest decreases were observed for secondary sulfate and nitrate species (58% and 44%, respectively). The amount of neutralization by ammonium did not change substantially over the time period in spite of substantial decreases in sulfate and nitrate concentrations. Total mobile source impacts decreased more at urban sites (39%) than rural sites (23%), whereas biomass burning decreased more at rural sites (34%) than urban sites (27%). The estimated central-site source impacts are found to spatially represent large areas for secondary pollutants, smaller areas for biomass burning and dust, and very local areas for mobile sources and coal combustion. Trends from the National Emissions Inventory were compared with the annual trends of mobile source impacts, coal combustion impacts, and sulfate concentrations, resulting in statistically significant positive trends with Pearson R2 of 0.80, 0.64, and 0.79, respectively. Results presented here suggest that PM2.5 reductions in Georgia and the Southeast have been achieved by control of both stationary and mobile sources, and that PM2.5 is comprised of increasing fractions of biomass burning emissions and suspended dust. The temporal trends of source impacts at each site adds information about source changes beyond the

  8. Impact of Middle Eastern dust sources on PM10 in Iran: Highlighting the impact of Tigris-Euphrates basin sources and Lake Urmia desiccation

    Science.gov (United States)

    Sotoudeheian, Saeed; Salim, Reza; Arhami, Mohammad

    2016-12-01

    Contribution of different Middle Eastern dust origins to PM10 (PM with aerodynamic diameters less than 10 µm) levels in several receptor large cities in Iran was investigated. Initially, the major regional dust episodes were determined through statistical analysis of recorded PM levels at air quality stations and verified using satellite images. The particles dispersion was simulated by Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) to regenerate PM10 during the dust episodes. The accuracy of the modeled results was rather convincing, with an average squared correlation coefficient (R2) of 0.7 (max = 0.95). Consequently, the contributions of different dust sources to the observed concentrations were determined. Basin of Tigris-Euphrates Rivers encompasses active dust sources with significant rate of emission due to fluvial deposits. The sources in this basin with approximately 70-95% contribution, by far, had the most influence on PM10 levels at the receptor cities. In a finer resolution, northern and central parts of Iraq had the most influence on PM10 level during the dust episodes. Effect of probable improvement or deterioration of the current dust origin conditions on PM10 levels was analyzed by performing a sensitivity analysis through varying threshold friction velocities. The results demonstrated that 10% increase or decrease in threshold friction velocities of major dust sources could lead to average of 51% decrease or 77% increase in the receptor cities' PM10, respectively. Finally, effects of Lake Urmia desiccation, as a new hydrological prospect dust origin were analyzed. The predicted dust from the prospective dried lake bed could result in 30-60% increase in PM10 of nearby cities during the studied dust episodes.

  9. Characterization of Modern and Fossil Mineral Dust Transported to High Altitude in the Western Alps: Saharan Sources and Transport Patterns

    Directory of Open Access Journals (Sweden)

    Florian Thevenon

    2012-01-01

    Full Text Available Mineral dust aerosols recently collected at the high-altitude Jungfraujoch research station (N, E; 3580 m a.s.l. were compared to mineral dust deposited at the Colle Gnifetti glacier (N, E; 4455 m a.s.l. over the last millennium. Radiogenic isotope signatures and backward trajectories analyses indicate that major dust sources are situated in the north-central to north-western part of the Saharan desert. Less radiogenic Sr isotopic compositions of PM10 aerosols and of mineral particles deposited during periods of low dust transfer likely result from the enhancement of the background chemically-weathered Saharan source. Saharan dust mobilization and transport were relatively reduced during the second part of the Little Ice Age (ca. 1690–1870 except within the greatest Saharan dust event deposited around 1770. After ca. 1870, sustained dust deposition suggests that increased mineral dust transport over the Alps during the last century could be due to stronger spring/summer North Atlantic southwesterlies and drier winters in North Africa. On the other hand, increasing carbonaceous particle emissions from fossil fuel combustion combined to a higher lead enrichment factor point to concomitant anthropogenic sources of particulate pollutants reaching high-altitude European glaciers during the last century.

  10. The Source Of Dust Jets Seen In Comet 103p/hartley 2.

    Science.gov (United States)

    Belton, Michael J. S.

    2012-10-01

    Comet 103P/Hartley 2 displays at least three different types of jet phenomena: highly structured CO2 driven jets seen in EPOXI encounter images (A’Hearn et al 2011), large scale jet phenomena that show in CN emission (e.g. Knight and Schleicher, 2012), and fainter dust jet or “cloud” structures seen in ground-based images (Lara et al., (2011), Mueller et al., (2012), Tozzi et al., 2012, Knight and Schleicher, 2012). The dust jets are observed to change their projected orientations slowly from night-to-night, and even during a night. From this behavior Knight and Schleicher (2012) have suggested that the source of the jets might be located near the comet’s total angular momentum vector and that they might be driven by CO, or more likely, CO2. In this paper we investigate the source of the dust jets using the shape modelof the comet’s nucleus (Thomas et al 2012) and a model of the comet’s complex spin state (Belton et al 2012) based on EPOXI observations. We show that the reason why the dust jet changes its projected direction is most likely the changing orientation of the surface at the sub-solar region during the spin cycle. In this scenario the jet source is not tied to the surface and is most likely driven by H2O sublimation. A’Hearn et al. 2011. Science 332, 1396-1400. Lara et al. 2011, A&A 532, A87 Mueller et al. 2012, AAS meeting 220, Abstract #120.03 Tozzi et al. 2012, preprint, submitted to Icarus Knight & Schleicher, 2012, Icarus, accepted for publication Thomas et al. 2012, Icarus, accepted for publication Belton et al. 2012, Icarus, accepted for publication

  11. A preliminary study on spatial unmasking of virtual separated sources

    Institute of Scientific and Technical Information of China (English)

    XIE ZhiWen; JIN Jing

    2008-01-01

    An experimental method with headphone virtual reproduction is proposed and a series of experiments to study forward masking effect when the masker and the masked signal are spatially separated in azimuth are conducted. Then, the masking thresholds are compared with those when the masker and the masked signal source are at the same place. The results show that, although both the thresholds of 0°and±30° sound images increase with the sound pressure level (SPL) of the masker, spatial unmasking may be really observed. The maximum unmasking is as large as 15 dB. This spatial unmasking effect is mainly attributed to better-ear con-tribution.

  12. A preliminary study on spatial unmasking of virtual separated sources

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An experimental method with headphone virtual reproduction is proposed and a series of experiments to study forward masking effect when the masker and the masked signal are spatially separated in azimuth are conducted. Then, the masking thresholds are compared with those when the masker and the masked signal source are at the same place. The results show that, although both the thresholds of 0° and ±30° sound images increase with the sound pressure level (SPL) of the masker, spatial unmasking may be really observed. The maximum unmasking is as large as 15 dB. This spatial unmasking effect is mainly attributed to better-ear contribution.

  13. Using geoaccumulation index to study source profiles of soil dust in China

    Institute of Scientific and Technical Information of China (English)

    JI Yaqin; FENG Yinchang; WU Jianhui; ZHU Tan; BAI Zhipeng; DUAN Chiqing

    2008-01-01

    Source apportionment studies of TSP(atmospheric particulate matter with aerodynamic diameters≤100μm)and PM10(atmospheric particulate matter with aerodynamic diameters≤10μm)have revealed that soil dust is all important source of these particulates in China In this study, the contamination of soil dust was assessed through the use of a geoaccumulation index(Igeo). The mass concentration profiles ofl7 elements(Na, Mg, AI, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Ba, andPb)were establishedforurban soil dusts. Geochemical cOmpositions of soils from 15 cities were used to represent background urban soil compositions. The results of this Studv indicated that a number of cities are severely polluted by particulates containing Ca, Cr, Ni, and Cu in both size fractions(TSP and PM10). Contamination with Zn, Pb, Co, and Br was moderate to severe(Igeo>2). The AI and Fe concentrations were not high enough for them to be considered contaminants.

  14. Planetary Magnetosphere Probed by Charged Dust Particles

    Science.gov (United States)

    Sternovsky, Z.; Horanyi, M.; Gruen, E.; Srama, R.; Auer, S.; Kempf, S.; Krueger, H.

    2010-12-01

    In-situ and remote sensing observations combined with theoretical and numerical modeling greatly advanced our understanding planetary magnetospheres. Dust is an integral component of the Saturnian and Jovian magnetospheres where it can act as a source/sink of plasma particles (dust particles are an effective source for plasma species like O2, OH, etc. through sputtering of ice particles, for example); its distribution is shaped by electrodynamic forces coupled radiation pressure, plasma, and neutral drag, for example. The complex interaction can lead to unusual dust dynamics, including the transport, capture, and ejection of dust grains. The study of the temporal and spatial evolution of fine dust within or outside the magnetosphere thus provides a unique way to combine data from a large number of observations: plasma, plasma wave, dust, and magnetic field measurements. The dust detectors on board the Galileo and Cassini spacecrafts lead to major discoveries, including the jovian dust stream originating from Io or the in-situ sampling and analysis of the plumes of Enceladus. Recent advancement in dust detector technology enables accurate measurement of the dust trajectory and elemental composition that can greatly enhance the understanding of dust magnetorspheric interaction and indentify the source of the dust with high precision. The capabilities of a modern dust detector thus can provide support for the upcoming Europa Jupiter System Mission.

  15. Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer

    Directory of Open Access Journals (Sweden)

    M. Yoshida

    2012-12-01

    Full Text Available There is a great deal of uncertainty surrounding the role of mineral dust aerosols in the earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction, are poorly understood because ground observations are limited to several locations and the satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength. We develop a method in this paper to estimate the spatial distributions of the aerosol single scattering albedo (ω0 and optical depth (τa, with daily 1 degree latitude and 1 degree longitude resolution, using data from Moderate Resolution Imaging Spectroradiometer (MODIS, as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We confirm that the uncertainties in our estimation of ω0 and τa are suitably minor and that the characteristic spatial distributions estimated over the Sahara and Asia are significant. The results for the Sahara indicate good correlation between ω0 and the surface reflectance and between ω0 and τa. Therefore, ω0 is determined mainly by the mineral composition of surface dust and/or the optical depth of airborne dust in the Sahara. On the other hand, the relationships between ω0, τa, and the surface reflectance are less clear in Asia than in the Sahara, and the values of ω0 are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are thought to be transported, as reported in previous studies. Because the coal-burning and carbonaceous

  16. Sedimentary and mineral dust sources of dissolved iron to the world ocean

    Directory of Open Access Journals (Sweden)

    J. K. Moore

    2008-05-01

    from sinking particles; and 3 an improved sedimentary source for dissolved iron. Most scavenged iron (90% is put on sinking particles to remineralize deeper in the water column. The model-observation differences are reduced with these modifications. The improved BEC model is used to examine the relative contributions of mineral dust and marine sediments in driving dissolved-iron distributions and marine biogeochemistry. Mineral dust and sedimentary sources of iron contribute roughly equally, on average, to dissolved iron concentrations. The sedimentary source from the continental margins has a strong impact on open-ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved-iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in the Southern Ocean allows the continental iron source to be advected far from sources. Both the margin sediment and mineral dust Fe sources substantially influence global-scale primary production, export production, and nitrogen fixation, with a stronger role for the dust source. Ocean biogeochemical models that do not include the sedimentary source for dissolved iron, will overestimate the impact of dust deposition variations on the marine carbon cycle. Available iron observations place some strong constraints on ocean biogeochemical models. Model results should be evaluated against both surface and subsurface Fe observations in the waters that supply dissolved iron to the euphotic zone.

  17. Integrated spatial multiplexing of heralded single photon sources

    CERN Document Server

    Collins, Matthew J; Rey, Isabella H; Vo, Trung D; He, Jiakun; Shahnia, Shayan; Reardon, Christopher; Steel, M J; Krauss, Thomas F; Clark, Alex S; Eggleton, Benjamin J

    2013-01-01

    The non-deterministic nature of photon sources is a key limitation for single photon quantum processors. Spatial multiplexing overcomes this by enhancing the heralded single photon yield without enhancing the output noise. Here the intrinsic statistical limit of an individual source is surpassed by spatially multiplexing two monolithic silicon correlated photon pair sources, demonstrating a 62.4% increase in the heralded single photon output without an increase in unwanted multi-pair generation. We further demonstrate the scalability of this scheme by multiplexing photons generated in two waveguides pumped via an integrated coupler with a 63.1% increase in the heralded photon rate. This demonstration paves the way for a scalable architecture for multiplexing many photon sources in a compact integrated platform and achieving efficient two photon interference, required at the core of optical quantum computing and quantum communication protocols.

  18. Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district

    Science.gov (United States)

    Witt, Emitt C.; Pribil, Michael; Hogan, John P; Wronkiewicz, David

    2016-01-01

    The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using 207Pb/206Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the 207Pb/206Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and 207Pb/206Pb of mining area dust suggest that 35.4–84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1–52.7% is associated with the smelter mixture, and 0–21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

  19. Isotopically constrained lead sources in fugitive dust from unsurfaced roads in the southeast Missouri mining district.

    Science.gov (United States)

    Witt, Emitt C; Pribil, Michael J; Hogan, John P; Wronkiewicz, David J

    2016-09-01

    The isotopic composition of lead (Pb) in fugitive dust suspended by a vehicle from 13 unsurfaced roads in Missouri was measured to identify the source of Pb within an established long-term mining area. A three end-member model using (207)Pb/(206)Pb and concentration as tracers resulted in fugitive dust samples plotting in the mixing field of well characterized heterogeneous end members. End members selected for this investigation include the (207)Pb/(206)Pb for 1) a Pb-mixture representing mine tailings, 2) aerosol Pb-impacted soils within close proximity to the Buick secondary recycling smelter, and 3) an average of soils, rock cores and drill cuttings representing the background conditions. Aqua regia total concentrations and (207)Pb/(206)Pb of mining area dust suggest that 35.4-84.3% of the source Pb in dust is associated with the mine tailings mixture, 9.1-52.7% is associated with the smelter mixture, and 0-21.6% is associated with background materials. Isotope ratios varied minimally within the operational phases of sequential extraction suggesting that mixing of all three Pb mixtures occurs throughout. Labile forms of Pb were attributed to all three end members. The extractable carbonate phase had as much as 96.6% of the total concentration associated with mine tailings, 51.8% associated with smelter deposition, and 34.2% with background. The next most labile geochemical phase (Fe + Mn Oxides) showed similar results with as much as 85.3% associated with mine tailings, 56.8% associated with smelter deposition, and 4.2% associated with the background soil.

  20. Enhancing weak transient signals in SEVIRI false colour imagery: application to dust source detection in southern Africa

    Science.gov (United States)

    Murray, Jon E.; Brindley, Helen E.; Bryant, Robert G.; Russell, Jacqui E.; Jenkins, Katherine F.

    2013-04-01

    Understanding the processes governing the availability and entrainment of mineral dust into the atmosphere requires dust sources to be identified and the evolution of dust events to be monitored. To achieve this aim a wide range of approaches have been developed utilising observations from a variety of different satellite sensors. Global maps of source regions and their relative strengths have been derived from instruments in low Earth orbit (e.g. Total Ozone Monitoring Spectrometer (TOMS) (Prospero et al., 2002), MODerate resolution Imaging Spectrometer (MODIS) (Ginoux et al., 2012)). Instruments such as MODIS can also be used to improve precise source location (Baddock et al., 2009) but the information available is restricted to the satellite overpass times which may not be coincident with active dust emission from the source. Hence, at a regional scale, some of the more successful approaches used to characterise the activity of different sources use high temporal resolution data available from instruments in geostationary orbit. For example, the widely used red-green-blue (RGB) dust scheme developed by Lensky and Rosenfeld (2008) (hereafter LR2008) makes use of observations from selected thermal channels of the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) in a false colour rendering scheme in which dust appears pink. This scheme has provided the basis for numerous studies of north African dust sources and factors governing their activation (e.g. Schepanski et al., 2007, 2009, 2012). However, the LR2008 imagery can fail to identify dust events due to the effects of atmospheric moisture, variations in dust layer height and optical properties, and surface conditions (Brindley et al., 2012). Here we introduce a new method designed to circumvent some of these issues and enhance the signature of dust events using observations from SEVIRI. The approach involves the derivation of a composite clear-sky signal for selected channels on an individual time-step and

  1. The structure of the protoplanetary disk surrounding three young intermediate mass stars. II. Spatially resolved dust and gas distribution

    CERN Document Server

    Fedele, D; Acke, B; van der Plas, G; Van Boekel, R; Wittkowski, M; Henning, T; Bouwman, J; Meeus, G; Rafanelli, P

    2008-01-01

    [Abridged] We present the first direct comparison of the distribution of the gas, as traced by the [OI] 6300 AA emission, and the dust, as traced by the 10 micron emission, in the protoplanetary disk around three intermediate-mass stars: HD 101412, HD 135344 B and HD 179218. N-band visibilities were obtained with VLTI/MIDI. Simple geometrical models are used to compare the dust emission to high-resolution optical spectra in the 6300 AA [OI] line of the same targets. The disks around HD 101412 and HD 135344 B appear strongly flared in the gas, but self-shadowed in the dust beyond ~ 2 AU. In both systems, the 10 micron emission is rather compact (< 2 AU) while the [OI] brightness profile shows a double peaked structure. The inner peak is strongest and is consistent with the location of the dust, the outer peak is fainter and is located at 5-10 AU. Spatially extended PAH emission is found in both disks. The disk around HD 179218 is flared in the dust. The 10 micron emission emerges from a double ring-like str...

  2. Chemical and Physical Characteristics of Sediments from Prevalent Dust Sources in the Central Chihuahuan Desert, Chihuahua, Mexico

    Science.gov (United States)

    Dominguez Acosta, M.; Gill, T. E.; Peinado, P.

    2013-05-01

    The Chihuahuan Desert has been recognized as an important contributor of mineral aerosols emplaced into the atmosphere in the Western Hemisphere. Along with the production of these aerosols, growing concern has been stated relating the downwind transport of atmospheric dust particles to increases in human health related impacts such as asthma and bronchitis in the Binational Paso Del Norte, the largest urban area in the region. Efforts have been made to describe the source types (land use/cover) and frequency of emission from the "dust hotspots" or prevalent sources within the region. These studies have outlined specific areas and their related sedimentological environments responsible for the regular dust production. Ephemeral lakes, fluvial and alluvial related environments form the main natural dust producing landforms in the region, modulated by short-term climatic variability and anthropogenic disturbance. Analysis of remote sensing imagery shows that the margins between natural areas and agricultural lands form the main anthropogenic related source areas. Most of the previously published studies focus on these remotely sensed descriptions of the dust sources, while only a few deal with in situ or field characteristics of these sources. A formal and detailed description of the physicochemical properties of many of these areas is presented, providing key data on this component of the overall dust production cycle. Elemental and mineralogical compositions of dust source sediments, soil textural compositions (grain size distributions) and field sedimentological descriptions are presented as an effort to attain a detailed in situ description of the prevalent dust sources in the central part of the Chihuahuan Desert.

  3. Metals and metalloids in atmospheric dust: Use of lead isotopic analysis for source apportionment

    Science.gov (United States)

    Felix Villar, Omar I.

    Mining activities generate aerosol in a wide range of sizes. Smelting activities produce mainly fine particles ( 1 microm). The adverse effects of aerosols on human health depend mainly on two key characteristics: size and chemical composition. One of the main objectives of this research is to analyze the size distribution of contaminants in aerosol produced by mining operations. For this purpose, a Micro-Orifice Uniform Deposit Impactor (MOUDI) was utilized. Results from the MOUDI samples show higher concentrations of the toxic elements like lead and arsenic in the fine fraction (Mitigation strategies could be developed if the source of contamination is well defined. Environmental conditions as wind speed, wind direction, relative humidity and precipitation have an important role in the concentration of atmospheric dust. Dry environments with low relative humidity are ideal for the transport of aerosols. Results obtained from this research show the relationship between dust concentrations and meteorological parameters. Dust concentrations are highly correlated with relative humidity and wind speed. With all the data collected on site and the analysis of the meteorological parameters, models can be develop to predict the transport of particles as well as the concentration of contaminants at a specific point. These models were developed and are part of the results shown in this dissertation.

  4. Soluble dust as source of nutrients to the oceans and the role of humans

    Science.gov (United States)

    Tsigaridis, K.; Kanakidou, M.; Myriokefalitakis, S.; Nikolaou, P.; Daskalakis, N.; Theodosi, C.; Nenes, A.; Mihalopoulos, N.

    2014-12-01

    Atmospheric deposition of trace constituents, both of natural and anthropogenic origin, can act as a nutrient source into the open ocean and affect marine ecosystem functioning and subsequently the exchange of CO2 between the atmosphere and the global ocean. Dust is known as a major source of nutrients (Fe and P) into the atmosphere, but only a fraction of these nutrients is released in soluble form that can be assimilated by the ecosystems. Dust is also known to enhance N deposition by interacting with anthropogenic pollutants and neutralisation of part of the acidity of the atmosphere by crustal alkaline species. The link between the soluble iron (Fe) and phosphorus (P) atmospheric deposition and atmospheric acidity, as well as anthropogenic sources, is investigated. The global atmospheric Fe, P and N cycle are parameterized in the global 3-D chemical transport model TM4-ECPL. Both primary emissions of total and soluble Fe and P associated with dust and combustion processes are taken into account, as well as inorganic and organic N emissions. The impact of atmospheric acidity on nutrient solubility is parameterised based on experimental findings. The model results are evaluated by comparison with available observations. The impact of air-quality changes on soluble nutrient deposition is studied by performing sensitivity simulations using preindustrial, present and future emission scenarios. The response of the chemical composition of nutrient-containing aerosols to environmental changes is demonstrated and quantified. This work has been supported by ARISTEIA - PANOPLY grant co-financed by European Union (ESF) and Greek national funds NSRF.

  5. Soluble dust as source of nutrients to the global ocean and the role of humans.

    Science.gov (United States)

    Kanakidou, Maria; Myriokefalitakis, Stelios; Nikolaou, Panagiota; Daskalakis, Nikos; Theodosi, Christina; Nenes, Athanassios; Tsigaridis, Kostas; Mihalopoulos, Nikos

    2015-04-01

    Atmospheric deposition of trace constituents, both of natural and anthropogenic origin, can act as a nutrient source into the open ocean and affect marine ecosystem functioning and subsequently the exchange of CO2 between the atmosphere and the global ocean. Dust is known as a major source of nutrients (Fe and P) into the atmosphere, but only a fraction of these nutrients is released in soluble form that can be assimilated by the ecosystems. Dust is also known to enhance N deposition by interacting with anthropogenic pollutants and neutralisation of part of the acidity of the atmosphere by crustal alkaline species. The link between the soluble iron (Fe) and phosphorus (P) atmospheric deposition and atmospheric acidity, as well as anthropogenic sources, is investigated. The global atmospheric Fe, P and N cycle are parameterized in the global 3-D chemical transport model TM4-ECPL. Both primary emissions of total and soluble Fe and P associated with dust and combustion processes are taken into account, as well as inorganic and organic N emissions. The impact of atmospheric acidity on nutrient solubility is parameterised based on experimental findings. The model results are evaluated by comparison with available observations. The impact of air-quality changes on soluble nutrient deposition is studied by performing sensitivity simulations using preindustrial, present and future emission scenarios. The response of the chemical composition of nutrient-containing aerosols to environmental changes is demonstrated and quantified. This work has been supported by ARISTEIA - PANOPLY grant co-financed by European Union (ESF) and Greek national funds NSRF.

  6. Temporal and spatial mapping of surface albedo and atmospheric dust opacity on Mars

    Science.gov (United States)

    Lee, S. W.; Clancy, R. T.; Gladstone, G. R.

    1993-01-01

    The Mariner 9 and Viking provided abundant evidence that eolian processes are active over much of the surface of Mars. Past studies have demonstrated that variations in regional albedo and wind-streak patterns are indicative of sediment transport through a region, while thermal inertia data (derived from the Viking Infrared Thermal Mapper (IRTM) dataset) are indicative of the degree of surface mantling by dust deposits. The visual and thermal data are therefore diagnostic of whether net erosion or deposition of dust-storm fallout is taking place currently and whether such processes have been active in a region over the long term. These previous investigations, however, have not attempted to correct for the effects of atmospheric dust loading on observations of the martian surface, so quantitative studies of current sediment transport rates have included large errors due to uncertainty in the magnitude of this 'atmospheric component' of the observations. We have developed a radiative transfer model that allows the atmospheric dust opacity to be determined from IRTM thermal observations. Corrections for the effects of atmospheric dust loading on observations of surface albedo can also be modeled. This approach to determining 'dust-corrected surface albedo' incorporates the atmospheric dust opacity, the single-scattering albedo and particle phase function of atmospheric dust, and the bidirectional reflectance of the surface, and it accounts for variable lighting and viewing geometry.

  7. Cosmic meteor dust: potentially the dominant source of bio-available iron in the Southern Ocean

    Science.gov (United States)

    Dyrud, L. P.; Marsh, D. R.; Del Castillo, C. E.; Fentzke, J.; Lopez-Rosado, R.; Behrenfeld, M.

    2012-12-01

    Johnson, 2001 [Johnson, Kenneth. S. (2001), Iron supply and demand in the upper ocean: Is extraterrestrial dust a significant source of bioavailable iron?, Global Biogeochem. Cycles, 15(1), 61-63, doi:10.1029/2000GB001295], first suggested that meteoric particulate flux could be a significant source of bio-available iron, particularly in regions with little or no eolean sources, such as the Southern Ocean. While these calculations raised intriguing questions, there were many large unknowns in the input calculations between meteor flux and bio-available ocean molecular densities. There has been significant research in the intervening decade on related topics, such as the magnitude (~200 ktons per year) and composition of the meteoric flux, its atmospheric evaporation, transport, mesospheric formation of potentially soluble meteoric smoke, and extraterrestrial iron isotope identification. Paramount of these findings are recent NCAR WACCM atmosphere model results demonstrating that the majority of meteoric constituents are transported towards the winter poles and the polar vortex. This may lead to a focusing of meteoritic iron deposition towards the Southern Ocean. We present a proposed research plan involving Southern Ocean sample collection and analysis and atmospheric and biological modeling to determine both the current relevance of meteoric iron, and examine the past and future consequences of cosmic dust under a changing climate.

  8. Spatial and temporal patterns of dust emissions (2004-2012) in semi-arid landscapes, southeastern Utah, USA

    Science.gov (United States)

    Flagg, Cody B.; Neff, Jason C.; Reynolds, Richard L.; Belnap, Jayne

    2013-01-01

    Aeolian dust can influence nutrient availability, soil fertility, plant interactions, and water-holding capacity in both source and downwind environments. A network of 85 passive collectors for aeolian sediment spanning numerous plant communities, soil types, and land-use histories covering approximately 4000 square kilometers across southeastern Utah was used to sample horizontal emissions of aeolian sediment. The sample archive dates to 2004 and is currently the largest known record of field-scale dust emissions for the southwestern United States. Sediment flux peaked during the spring months in all plant communities (mean: 38.1 g m−2 d−1), related to higher, sustained wind speeds that begin in the early spring. Dust flux was lowest during the winter period (mean: 5 g m−2 d−1) when surface wind speeds are typically low. Sites dominated by blackbrush and sagebrush shrubs had higher sediment flux (mean: 19.4 g m−2 d−1) compared to grasslands (mean: 11.2 g m−2 d−1), saltbush shrublands (mean: 10.3 g m−2 d−1), and woodlands (mean: 8.1 g m−2 d−1). Contrary to other studies on dust emissions, antecedent precipitation during one, two, and three seasons prior to sample collection did not significantly influence emission rates. Physical site-scale factors controlling dust emissions were complex and varied from one vegetation type to another.

  9. Characteristics of PM10 Chemical Source Profiles for Geological Dust from the South-West Region of China

    Directory of Open Access Journals (Sweden)

    Yayong Liu

    2016-11-01

    Full Text Available Ninety-six particulate matter (PM10 chemical source profiles for geological sources in typical cities of southwest China were acquired from Source Profile Shared Service in China. Twenty-six elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sn, Sb, Ba, Be, Tl and Pb, nine ions (F−, Cl−, SO42−, NO3−, Na+, NH4+, K+, Mg2+ and Ca2+, and carbon-containing species (organic carbon and elemental carbon were determined to construct these profiles. Individual source profiles were averaged and compared to quantify similarities and differences in chemical abundances using the profile-compositing method. Overall, the major components of PM10 in geological sources were crustal minerals and undefined fraction. Different chemical species could be used as tracers for various types of geological dust in the region that resulted from different anthropogenic influence. For example, elemental carbon, V and Zn could be used as tracers for urban paved road dust; Al, Si, K+ and NH4+ for agricultural soil; Al and Si for natural soil; and SO42− for urban resuspended dust. The enrichment factor analysis showed that Cu, Se, Sr and Ba were highly enriched by human activities in geological dust samples from south-west China. Elemental ratios were taken to highlight the features of geological dust from south-west China by comparing with northern urban fugitive dust, loess and desert samples. Low Si/Al and Fe/Al ratios can be used as markers to trace geological sources from southwestern China. High Pb/Al and Zn/Al ratios observed in urban areas demonstrated that urban geological dust was influenced seriously by non-crustal sources.

  10. Spatially Resolved 3 um Spectroscopy of IRAS 22272+5435 Formation and Evolution of Aliphatic Hydrocarbon Dust in Proto-Planetary Nebula

    CERN Document Server

    Goto, M; Hayano, Y; Iye, M; Kamata, Y; Kanzawa, T; Kobayashi, N; Minowa, Y; Saint-Jacques, D J; Takami, H; Takato, N; Terada, H

    2003-01-01

    We present medium-resolution 3 um spectroscopy of the carbon-rich proto-planetary nebula IRAS 22272+5435. Spectroscopy with the Subaru Telescope adaptive optics system revealed a spatial variation of hydrocarbon molecules and dust surrounding the star. The ro-vibrational bands of acetylene (C2H2) and hydrogen cyanide (HCN) at 3.0 um are evident in the central star spectra. The molecules are concentrated in the compact region near the center. The 3.3 and 3.4 um emission of aromatic and aliphatic hydrocarbons is detected at 600--1300 AU from the central star. The separation of spatial distribution between gas and dust suggests that the small hydrocarbon molecules are indeed the source of solid material, and that the gas leftover from the grain formation is being observed near the central star. The intensity of aliphatic hydrocarbon emission relative to the aromatic hydrocarbon emission decreases with distance from the central star. The spectral variation is well matched to that of a laboratory analog thermally ...

  11. The mineral composition and spatial distribution of the dust ejecta of NGC 6302

    CERN Document Server

    Kemper, F; Jäger, C; Waters, L B F M

    2002-01-01

    We have analysed the full ISO spectrum of the planetary nebula NGC 6302 in order to derive the mineralogical composition of the dust in the nebula. We use an optically thin dust model in combination with laboratory measurements of cosmic dust analogues. We find two main temperature components at about 100 and 50 K respectively, with distinctly different dust compositions. The warm component contains an important contribution from dust without strong infrared resonances. In particular the presence of small warm amorphous silicate grains can be excluded. The detection of weak PAH bands also points to a peculiar chemical composition of the dust in this oxygen-rich nebula. The cool dust component contains the bulk of the mass and shows strong emission from crystalline silicates, which contain about 10 percent of the mass. In addition, we identify the 92 micron band with the mineral calcite, and argue that the 60 micron band contains a contribution from the carbonate dolomite. We present the mass absorption coeffi...

  12. Simulation of the spatial distribution of mineral dust and its direct radiative forcing over Australia

    Directory of Open Access Journals (Sweden)

    Omid Alizadeh Choobari

    2013-05-01

    Full Text Available Direct radiative forcing by mineral dust is important as it significantly affects the climate system by scattering and absorbing short-wave and long-wave radiation. The multi-angle imaging spectro radiometer (MISR and cloud–aerosol lidar with orthogonal polarisation (CALIOP aerosol data are used to observe mineral dust distribution over Australia. In addition, the weather research and forecasting with chemistry (WRF/Chem model is used to estimate direct radiative forcing by dust. At the surface, the model domain clear-sky short-wave and long-wave direct radiative forcing by dust averaged for a 6-month period (austral spring and summer was estimated to be −0.67 W m−2 and 0.13 W m−2, respectively. The long-wave warming effect of dust therefore offsets 19.4% of its short-wave cooling effect. However, over Lake Eyre Basin where coarse particles are more abundant, the long-wave warming effect of dust offsets 60.9% of the short-wave cooling effect. At the top of the atmosphere (TOA, clear-sky short-wave and long-wave direct radiative forcing was estimated to be −0.26 W m−2 and −0.01 W m−2, respectively. This leads to a net negative direct radiative forcing of dust at the TOA, indicating cooling of the atmosphere by an increase in outgoing radiation. Short-wave and long-wave direct radiative forcing by dust is shown to have a diurnal variation due to changes in solar zenith angle and in the intensity of infrared radiation. Atmospheric heating due to absorption of short-wave radiation was simulated, while the interaction of dust with long-wave radiation was associated with atmospheric cooling. The net effect was cooling of the atmosphere near the surface (below 0.2 km, with warming of the atmosphere at higher altitudes.

  13. Mineral Dust Analysis and Application in Refining Source Region Information for the Sahara and East Asia Deserts

    Science.gov (United States)

    Reid, E. A.; Reid, J. S.; Westphal, D.; Cliff, S.; Dunlap, M.

    2002-12-01

    The study of transported mineral dust aerosols relies heavily on simplified dust source region parameters. Source regions are broadly defined by soil class and expected erodibility, factors which continuously changes with land use and climate conditions. Mineral dust particles may undergo numerous cycles of deposition and re-entrainment prior to collection and analysis. Using the Sahara Desert and the East Asia deserts as test cases, we investigate the possibility of retrieving source information from receptor sites through single particle and bulk analyses of collected aerosol particles. In June and July of 2000, Saharan mineral dust aerosols transported across the Atlantic Ocean to Puerto Rico were collected for bulk and single particle chemical and morphological analyses. The Puerto Rico Dust Experiment, (PRIDE), involved sampling aerosols upwind of the islands at various altitudes in the marine boundary layer (MBL) and Saharan Air Layer (SAL) via a Navajo research aircraft. A surface site included a Davis Rotating Drum (DRUM) cascade impactor to size segregate the aerosols into eight stages, from 12 to 0.1 micrometers, with four-hour time resolution. In April of 2001, size segregated Asian mineral dust aerosols were collected by three hour resolution DRUM samplers at surface sites in Cheju, Taiwan, for bulk chemical analysis. The aircraft samples and selected DRUM samples were subjected to single particle analysis by scanning electron microscopy (SEM) for particle morphology, and by Energy Dispersive Analysis with X-rays (EDAX) to derive elemental ratios of key soil elements. The DRUM samples were subjected to X-Ray Fluorescence (XRF) to derive bulk elemental composition for elements Al though Zn. Cluster and principal component analysis of the data derived statistically significant particle groupings. By including particle morphology data, and using ternary analyses, derivation of additional source information was possible. Particle compositions

  14. Distribution of dust during two dust storms in Iceland

    Science.gov (United States)

    Ösp Magnúsdóttir, Agnes; Dagsson-Waldhauserova, Pavla; Arnalds, Ólafur; Ólafsson, Haraldur

    2017-04-01

    Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 ?g?m?3 (PM10 = 7 to 583 ?g?m?3). The mean PM1 concentrations were 97-241 ?g?m?3 with a maximum of 261 ?g?m?3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34-0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

  15. Distinguishing the Asian dust sources based on cathodoluminescence analysis of single quartz grain

    Science.gov (United States)

    Nagashima, K.; Nishido, H.; Kayama, M.; Tada, R.; Isozaki, Y.; Sun, Y.; Igarashi, Y.

    2009-12-01

    Numerous tracers, such as mineralogical component, strontium (87Sr/86Sr) and neodymium (eNd(0)) isotopes (Liu et al., 1994; Biscaye et al.,1997; Bory et al., 2002, 2003; Kanayama et al., 2002, 2005), rare earth element composition (e.g., Svensson et al., 2000), oxygen isotope (Mizota et al., 1992; Hou et al., 2003) and ESR intensity of quartz (Ono et al., 1998; Sun et al., 2007), have been investigated to discriminate source areas of Asian dust. However, these analyses need large volume of samples (mostly more than 10 mg) and the applications to the dust samples are limited. Then, here we developed a provenance-tracing method by using a cathodoluminescence (CL) spectral of “single” quartz grain for applying it to small volume of aeolian dust samples, such as aeolian dust in the ice cores and marine sediments with the location of long distance from the Asian deserts. CL is the emission from a material which is excited by electron beam. Since CL spectroscopy and microscopy provide information on the existence and distribution of defects and trace elements in minerals, CL analyses have potential to characterize dust-source areas. CL spectra of quartz have been demonstrated to show different patterns between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins (e.g., Zinkernagel, 1978; Götze et al., 2001), suggesting the spectra reflect the condition of the quartz formation and the local environment. Then, here we conducted CL spectral analysis of silt size quartz in the surface samples from the major Asian deserts, such as the Taklimakan Desert and Gobi Desert in southern Mongolia (hereafter Mongolian Gobi). CL spectra were measured in the areas of approximately 4 micron square for each quartz grain by a Scanning Electron Microscope-Cathodoluminescence (SEM-CL) at the Okayama University of Science, a SEM (Jeol: JSM-5410) attached with a grating monochromator (Oxford Instruments: Mono CL2), where EDS system can be used in combination with SEM

  16. Case study of the Asian dust and pollutant event in spring 2006: source, transport, and contribution to Taiwan.

    Science.gov (United States)

    Tsai, Fujung; Tu, Jien-Yi; Hsu, Shih-Chieh; Chen, Wei-Nai

    2014-04-15

    Surface measurements and a regional dust model were used to analyze the source, transport, and contribution of a dust event transporting with aerosol pollutant over Taiwan from 16 to 19 March, 2006. During the event, the hourly aerosol concentrations reached close to 400 μg m(-3) in northern Taiwan, and approximately 300 μg m(-3) in other areas of the island. Trajectory and regional dust models show that the dust event originated in eastern Mongolia and northern China, and the dust layer can descend from 2 to 3 km in the source area to below 1.5 km over Taiwan. On the other hand, model results show that pollution was transported near the surface from coastal China to Taiwan. During this dust event, polluted aerosol was first observed over northern Taiwan right after a frontal passage, and the concentration was strongly enhanced following the passage of the light rainfall 12h later. The descent of dusty air from the free troposphere lagged the arrival of polluted air by 7h, and was partially mixed with polluted aerosol when the transport decelerated over Taiwan. During the event, dust particles accounted for up to 60% of observed particulate matter less than 10 μm (PM10) over Taiwan, but decreased to less than 35% for particulate matter less than 2.5 μm (PM2.5) over most areas of the island. On the other hand, the long-range transport of non-dust aerosols, mainly anthropogenic pollutants, accounted for close to 30% of observed PM10 concentration in northern and western Taiwan prior to dust arrival, and the contribution of PM2.5 increased to close to 40% over the same areas. Local emission of aerosols accounted for less than 25% of PM10 concentrations in northern Taiwan, but was about 60% for PM2.5 in central and southern Taiwan because these areas are less influenced by long-range transport.

  17. Sources of hydrocarbons in urban road dust: Identification, quantification and prediction.

    Science.gov (United States)

    Mummullage, Sandya; Egodawatta, Prasanna; Ayoko, Godwin A; Goonetilleke, Ashantha

    2016-09-01

    Among urban stormwater pollutants, hydrocarbons are a significant environmental concern due to their toxicity and relatively stable chemical structure. This study focused on the identification of hydrocarbon contributing sources to urban road dust and approaches for the quantification of pollutant loads to enhance the design of source control measures. The study confirmed the validity of the use of mathematical techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA) for source identification and principal component analysis/absolute principal component scores (PCA/APCS) receptor model for pollutant load quantification. Study outcomes identified non-combusted lubrication oils, non-combusted diesel fuels and tyre and asphalt wear as the three most critical urban hydrocarbon sources. The site specific variabilities of contributions from sources were replicated using three mathematical models. The models employed predictor variables of daily traffic volume (DTV), road surface texture depth (TD), slope of the road section (SLP), effective population (EPOP) and effective impervious fraction (EIF), which can be considered as the five governing parameters of pollutant generation, deposition and redistribution. Models were developed such that they can be applicable in determining hydrocarbon contributions from urban sites enabling effective design of source control measures.

  18. Dust aerosols over India and adjacent continents retrieved using METEOSAT infrared radiance Part I: sources and regional distribution

    Directory of Open Access Journals (Sweden)

    J. Srinivasan

    2006-03-01

    Full Text Available Mineral dust constitutes the single largest contributor to continental aerosols. To accurately assess the impact of dust aerosols on climate, the spatial and temporal distribution of dust radiative properties is essential. Regional characteristics of dust radiative properties, however, are poorly understood. The magnitude and even sign of dust radiative forcing is uncertain, as it depends on a number of parameters, such as vertical distribution of dust, cloud cover and albedo of the underlying surface. In this paper, infrared radiance (10.5-12.5 µm, acquired from the METEOSAT-5 satellite ( resolution, was used to retrieve regional characteristics of dust aerosols for all of 1999. The infrared radiance depression, due to the presence of dust in the atmosphere, has been used as an index of dust load, known as the Infrared Difference Dust Index (IDDI. There have been several studies in the past carried out over the Sahara using IDDI as a measure of dust load. Over the Indian region, however, studies on dust aerosols are sparse. Spatial and temporal variability in dust loading and its regional distribution over various arid and semiarid regions of India and adjacent continents (0-35° N; 30° E-100° E (excluding Sahara have been studied and the results are examined along with surface soil conditions (such as vegetation cover and soil moisture. The advantage of the IDDI method is that information on aerosol properties, such as chemical composition or microphysical properties, is not needed. A large day-to-day variation in IDDI was observed over the entire study region, with values ranging from 4 to 22 K. It was observed that dust activity starts by March over the Indian deserts, as well as over deserts of the Africa and Arabian regions. The IDDI reaches maximum during the period of May to August. Regional maps of IDDI, in conjunction with biomass burning episodes (using TERRA satellite fire pixel counts, suggest that large IDDI values observed

  19. Source, transport and impacts of a heavy dust event in the Yangtze River Delta, China in 2011

    Directory of Open Access Journals (Sweden)

    X. Fu

    2013-08-01

    Full Text Available During 1 to 6 May 2011, a dust event was observed in the Yangtze River Delta region (YRD. The highest PM10 concentration reached over 1000 μg m−3 and the visibility was below 3 km. In this study, the Community Multi-scale Air Quality modeling system (CMAQ5.0 coupled with an in-line windblown dust model was used to simulate the formation, spatial and temporal characteristics of this dust event, and analyze its impacts on deposition and photochemistry. The threshold friction velocity for loose smooth surface in the dust model was revised based on Chinese data to improve the model performance. The comparison between predictions and observations indicates the revised model can reproduce the transport and pollution of the event. The simulation results show that the dust event was affected by formation and transport of Mongolian cyclone and cold air. Totally about 695 kt dust particles (PM10 were emitted in Xinjiang Province and Mongolia during 28 to 30 April, the dust band swept northern, eastern China and then arrived in the YRD region on 1 May 2011. The transported dust particles increased the mean surface layer concentrations of PM10 in the YRD region by 372% during 1 to 6 May and the impacts weakened from north to south due to the removal of dust particles along the path. Accompanied by high PM concentration, the dry deposition, wet deposition and total deposition of PM10 in the YRD reached 184.7 kt, 172.6 kt and 357.32 kt, respectively. These deposited particles are very harmful because of their impacts on urban environment as well as air quality and human health when resuspending in the atmosphere. Due to the impacts of mineral dust on atmospheric photolysis, the concentrations of O3 and OH were reduced by 1.5% and 3.1% in the whole China, and by 9.4% and 12.1% in the YRD region, respectively. The work of this manuscript is meaningful for understanding the dust emissions in China as well as for the application of CMAQ in Asia. It is also

  20. Ensemble filter based estimation of spatially distributed parameters in a mesoscale dust model: experiments with simulated and real data

    Directory of Open Access Journals (Sweden)

    V. M. Khade

    2013-03-01

    Full Text Available The ensemble adjustment Kalman filter (EAKF is used to estimate the erodibility fraction parameter field in a coupled meteorology and dust aerosol model (Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS over the Sahara desert. Erodibility is often employed as the key parameter to map dust source. It is used along with surface winds (or surface wind stress to calculate dust emissions. Using the Saharan desert as a test bed, a perfect model Observation System Simulation Experiments (OSSEs with 40 ensemble members, and observations of aerosol optical depth (AOD, the EAKF is shown to recover correct values of erodibility at about 80% of the points in the domain. It is found that dust advected from upstream grid points acts as noise and complicates erodibility estimation. It is also found that the rate of convergence is significantly impacted by the structure of the initial distribution of erodibility estimates; isotropic initial distributions exhibit slow convergence, while initial distributions with geographically localized structure converge more quickly. Experiments using observations of Deep Blue AOD retrievals from the MODIS satellite sensor result in erodibility estimates that are considerably lower than the values used operationally. Verification shows that the use of the tuned erodibility field results in better predictions of AOD over the west Sahara and the Arabian Peninsula.

  1. Measurment of threshold friction velocities at potential dust sources in semi-arid regions

    Science.gov (United States)

    King, Matthew A.

    The threshold friction velocities of potential dust sources in the US Southwest were measured in the field using a Portable Wind Tunnel, which is based on the Desert Research Institute's Portable In-Situ Wind Erosion Laboratory (PI-SWERL). A mix of both disturbed and undisturbed surfaces were included in this study. It was found that disturbed surfaces, such as those at the Iron King Mine tailings site, which is part of the EPA's Superfund program and contains surface concentrations of arsenic and lead reaching as high as 0.5% (w/w), had lower threshold friction velocities (0.32 m s -1 to 0.40 m s-1) in comparison to those of undisturbed surfaces (0.48 to 0.61 m s-1). Surface characteristics, such as particle size distribution, had effects on the threshold friction velocity (smaller grain sized distributions resulted in lower threshold friction velocities). Overall, the threshold friction velocities of disturbed surfaces were within the range of natural wind conditions, indicating that surfaces disturbed by human activity are more prone to causing windblown dust.

  2. Spatially unassociated galaxies contribute significantly to the blended submillimetre galaxy population: predictions for follow-up observations of ALMA sources

    CERN Document Server

    Hayward, Christopher C; Somerville, Rachel S; Primack, Joel R; Moreno, Jorge; Wechsler, Risa H

    2013-01-01

    There is anecdotal evidence that spatially and physically unassociated galaxies blended into a single submillimetre (submm) source contribute to the submm galaxy (SMG) population. However, the significance of this subpopulation has neither been observationally constrained nor theoretically predicted. This work is the first to theoretically predict the contribution of spatially unassociated components to the SMG population. We generate mock SMG catalogues using lightcones derived from the Bolshoi cosmological simulation; to assign submm flux densities to the mock galaxies, we use a fitting function previously derived from the results of dust radiative transfer performed on hydrodynamical simulations of isolated disc and merging galaxies. We then calculate submm number counts for different beam sizes and without blending. Our model suggests that there are a sufficient number of blended SMGs to account for the observed number counts of submm sources with 850-{\\mu}m flux density S_850 >~12 mJy. Furthermore, we pr...

  3. Sources of polycyclic aromatic hydrocarbons (PAHs) in street dust in a tropical Asian mega-city, Bangkok, Thailand.

    Science.gov (United States)

    Boonyatumanond, Ruchaya; Murakami, Michio; Wattayakorn, Gullaya; Togo, Ayako; Takada, Hideshige

    2007-10-01

    We collected samples of roadside air, automobile exhaust soot, tires, asphalt, and used engine oil in a tropical Asian mega-city, Bangkok, Thailand, and analyzed them for polycyclic aromatic hydrocarbons (PAHs) and hopanes. The concentrations and compositions of PAHs and hopanes were utilized to identify the sources of PAHs in street dust, in which high concentrations of PAHs were reported in our previous study. Weight-based concentrations of total PAHs had the following order: gasoline-powered vehicle soot (2600+/-2900 microg/g; n=4)>diesel-powered vehicle soot (115+/-245 microg/g; n=7) approximately roadside aerosols (101+/-35 microg/g; n=5) approximately used engine oil (97+/-65 microg/g; n=4) approximately tire wear particles (82+/-41 microg/g; n=5)>asphalt (2.3+/-1.6 microg/g; n=3)>street dust (1.1+/-0.8 microg/g; n=10). In cluster analysis, all the source materials fell into different clusters from that in which street dust fell, indicating that multiple source materials contribute to PAHs in the street dust. Multiple regression analysis of PAH profiles and diagnostics of hopane compositions identified tire debris as the major contributor of PAHs to street dust, followed by diesel vehicle exhaust.

  4. Axial dissipative dust as a source of gravitational radiation in f(R) gravity

    Science.gov (United States)

    Sharif, M.; Siddiqa, Aisha

    2017-03-01

    In this paper, we explore the source of gravitational radiation in the context of f(R) gravity by considering axially symmetric dissipative dust under geodesic condition. We evaluate scalars associated with electric and magnetic parts of the Weyl tensor for both non-spinning (at the center) and spinning (in the surrounding of the center) fluids of the configuration. For this purpose, we use the evolution as well as constraint equations for kinematical quantities and Weyl tensor. Finally, we investigate the existence of gravitational radiation through super-Poynting vector. It is found that the fluid is not gravitationally radiating in the non-spinning case but it is gravitationally radiating for the spinning case.

  5. Spatial distribution of interstellar dust in the Sun's vicinity. Comparison with neutral sodium-bearing gas

    Science.gov (United States)

    Vergely, J.-L.; Valette, B.; Lallement, R.; Raimond, S.

    2010-07-01

    Aims: 3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the interstellar medium itself to foreground decontamination of the cosmic microwave background, or various studies of the environments of specific objects. However, while spectral data cubes of the galactic emission become increasingly precise, the information on the distance to the emitting regions has not progressed as well and relies essentially on the galactic rotation curve. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. Methods: We apply the best available calibration methods to a carefully screened set of stellar Strömgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion, optimized for this specific data set. We apply the same inversion technique to a totally independent set of neutral sodium absorption data available for about 1700 target stars. Results: We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds within 250 pc and identify in those maps well-known dark clouds and high galactic more diffuse entities. We calculate the integrated extinction between the Sun and the cube boundary and compare this with the total galactic extinction derived from infrared 2D maps. The two quantities reach similar values at high latitudes, as expected if the local dust content is satisfyingly reproduced and the dust is closer than 250 pc. Those maps show a larger high latitude dust opacity in the North compared to the South, reinforcing earlier evidences. Interestingly the gas maps do not show the same asymmetry, suggesting a polar asymmetry of the dust to gas

  6. Tunable optical microwave source using spatially resolved laser eigenstates.

    Science.gov (United States)

    Brunel, M; Bretenaker, F; Le Floch, A

    1997-03-15

    A two-propagation-axis solid-state laser is shown to provide a widely tunable optical microwave source. The spatial separation of the laser eigenstates is shown to enable an étalon to act as a coarse tuner, forcing oscillation in any nonadjacent cavity modes. The frequency difference between opposite helicoidal eigenstates operating in nonadjacent cavity modes can then be tuned continuously. The beat note from such a solid-state laser is shown to vary from dc to 26 GHz, i.e., 30 times the laser free-spectral range, and is limited only by the free-spectral range of the étalon.

  7. A search for precursors of Ultracompact HII Regions in a sample of luminous IRAS sources; 3, Circumstellar Dust Properties

    CERN Document Server

    Molinari, S; Cesaroni, R; Palla, Fabrizio; Molinari, Sergio; Brand, Jan; Cesaroni, Riccardo; Palla, Francesco

    2000-01-01

    The James Clerk Maxwell Telescope has been used to obtain submillimeter and millimeter continuum photometry of a sample of 30 IRAS sources previously studied in molecular lines and centimeter radio continuum. All the sources have IRAS colours typical of very young stellar objects (YSOs) and are associated with dense gas. In spite of their high luminosities (L>10000 solar units), only ten of these sources are also associated with a radio counterpart. In 17 cases we could identify a clear peak of millimeter emission associated with the IRAS source, while in 9 sources the millimeter emission was extended or faint and a clear peak could not be identified; upper limits were found in 4 cases only. Using simple greybody fitting model to the observed SED, we derive global properties of the circumstellar dust. The dust temperature varies from 24 K to 45 K, while the exponent of the dust emissivity vs frequency power-law spans a range 1.56dust; total circumstellar masses ran...

  8. A Sr-Nd-Hf isotope characterization of dust source areas in Victoria Land and the McMurdo Sound sector of Antarctica

    Science.gov (United States)

    Blakowski, Molly A.; Aciego, Sarah M.; Delmonte, Barbara; Baroni, Carlo; Salvatore, Maria Cristina; Sims, Kenneth W. W.

    2016-06-01

    Determining the geographical provenance of dust provides crucial insight into the global dust cycle. For the East Antarctic Ice Sheet (EAIS), the importance of Southern hemisphere potential dust sources has been thoroughly investigated using radiogenic isotopes, whereas proximal dust source areas located on the periphery of the ice sheet remain poorly documented from a geochemical standpoint. In this work, we expand the existing isotopic (Srsbnd Nd) catalogue of dust and sand-sized sediments from Victoria Land and the McMurdo Sound sector, and incorporate Hf isotopic data to place additional constraints on dust source identification. The isotopic field for materials considered in this study is characterized by 87Sr/86Sr ratios ranging from 0.703 to 0.783, εNd between -12.01 and 6.36, and εHf from -16.77 to 6.89. As reported in previous works, the data reveal close relationships between Antarctic sediments and distinct parent lithologies; in addition, our findings emphasize the background presence of very fine dusts originating from dominant global sources and regional volcanic activity as barriers to direct source-to-sink comparison of isotopic signatures. Thus, geochemical characterizations of dust sources to the Antarctic ice sheet involving multiple size fractions, including coarser-grained particles more susceptible to short-range transport, can help us to rule out global sources of dust when examining local sediment cores and ice cores.

  9. Spatially-resolved dust properties of the GRB 980425 host galaxy

    DEFF Research Database (Denmark)

    Michałowski, Michał J.; Hunt, L. K.; Palazzi, E.

    2014-01-01

    ), located 800 pc away from the GRB position. The host is characterised by low dust content and high fraction of UV-visible star-formation, similar to other dwarf galaxies. Such galaxies are abundant in the local universe, so it is not surprising to find a GRB in one of them, assuming the correspondence...

  10. Spatial distribution of interstellar dust in the Sun vicinity, comparison with neutral sodium-bearing gas

    CERN Document Server

    Vergely, Jean-Luc; Lallement, Rosine; Raimond, Severine

    2010-01-01

    3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the ISM itself to foreground decontamination of the CMB, or various studies of the environments of specific objects. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. We apply the best available calibration methods to a carefully screened set of stellar Stromgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6,000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion. We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds with 250 pc. We calculate the integrated extinction between the Sun and the cube boundary and compare with the total galactic extinction derived f...

  11. Organic contaminants and heavy metals in indoor dust from e-waste recycling, rural, and urban areas in South China: Spatial characteristics and implications for human exposure.

    Science.gov (United States)

    He, Chun-Tao; Zheng, Xiao-Bo; Yan, Xiao; Zheng, Jing; Wang, Mei-Huan; Tan, Xiao; Qiao, Lin; Chen, She-Jun; Yang, Zhong-Yi; Mai, Bi-Xian

    2017-02-27

    The concentrations of several organic contaminants (OCs) and heavy metals were measured in indoor dust from e-waste recycling, rural, and urban areas in South China to illustrate the spatial characteristics of these pollutants and to further evaluate human exposure risks. The median concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DPs) were 38.6-3560, 2360-30,100, 665-2720, and 19.5-1860ng/g, while the median concentrations of Cd, Pb, Cu, Cr, and Zn were 2.46-40.4, 206-1380, 217- 1200, 25.3-134, and 176-212μg/g in indoor dust. The levels of all pollutants, except Zn, in dust from the e-waste recycling area were significantly higher than those from the other areas. Cd, Pb, and most OCs exhibited similar pollution patterns in the three areas, indicating that e-waste recycling activities are the major pollution source. In contrast, Cu, Cr, Zn, and penta-BDE are likely derived from household products in the rural and urban areas. The highest estimated daily intakes (EDIs) of PCBs, PBDEs, DBDPE, and DPs were 0.15-163, 3.97-1470, 1.26-169, and 0.11-134ng/kg bw/day for toddlers and adults. The highest EDIs of BDE 209 and Pb in toddlers in the e-waste recycling area were 16% and 18 times higher than the reference doses, indicating the high exposure risk of these pollutants in the e-waste recycling area.

  12. Anthropogenic Enrichment of Heavy Metals in Urban Dust and Possible Corresponding Sources

    Science.gov (United States)

    van Laaten, Neele; Merten, Dirk; Pirrung, Michael

    2017-04-01

    Atmospheric dust (particulate matter, PM) is regarded as a crucial factor for human health and a major environmental problem in densely populated areas. Due to anthropogenic processes like traffic, waste incineration and industry increased amounts of PM can be detected in those areas. To reduce the amounts detailed knowledge on both the composition of PM and the source contribution in a target area is needed. The latter has, to our knowledge, rarely been regarded in central Europe. Within this study, spider webs from various locations in the city of Jena (Germany), that act as natural trappers of PM, were analyzed for the contents of 27 trace elements using aqua regia digestion followed by ICP-OES and ICP-MS determinations. Aerosol-crust enrichment factors were calculated for selected elements and both a cluster analysis and a factor analysis were executed to identify sources of PM. High values for the enrichment factors clearly show an anthropogenic influence. In addition, the cluster analysis leads to a grouping of the sampling points mainly depending on the kind and volume of traffic at the corresponding locations. Five different possible sources of PM can be found by the factor analysis: Soil erosion (41% of variance), abrasion of rails (16%), tyre and break wear (16%), charcoal combustion (8%) and oil combustion (7%).

  13. Composition of dust deposited to snow cover in the Wasatch Range (Utah, USA): Controls on radiative properties of snow cover and comparison to some dust-source sediments

    Science.gov (United States)

    Reynolds, Richard L.; Goldstein, Harland L.; Moskowitz, Bruce M.; Bryant, Ann C.; Skiles, S. McKenzie; Kokaly, Raymond F.; Flagg, Cody B.; Yauk, Kimberly; Berquó, Thelma S.; Breit, George N.; Ketterer, Michael; Fernandez, Daniel; Miller, Mark E.; Painter, Thomas H.

    2014-01-01

    Dust layers deposited to snow cover of the Wasatch Range (northern Utah) in 2009 and 2010 provide rare samples to determine the relations between their compositions and radiative properties. These studies are required to comprehend and model how such dust-on-snow (DOS) layers affect rates of snow melt through changes in the albedo of snow surfaces. We evaluated several constituents as potential contributors to the absorption of solar radiation indicated by values of absolute reflectance determined from bi-conical reflectance spectroscopy. Ferric oxide minerals and carbonaceous matter appear to be the primary influences on lowering snow-cover albedo. Techniques of reflectance and Mössbauer spectroscopy as well as rock magnetism provide information about the types, amounts, and grain sizes of ferric oxide minerals. Relatively high amounts of ferric oxide, indicated by hard isothermal remanent magnetization (HIRM), are associated with relatively low average reflectance (hematite and goethite, representing about 35% of the total Fe-bearing phases. Nevertheless, goethite (α-FeOOH) is the dominant ferric oxide found by reflectance spectroscopy and thus appears to be the main iron oxide control on absorption of solar radiation. At least some goethite occurs as nano-phase grain coatings less than about 50 nm thick. Relatively high amounts of organic carbon, indicating as much as about 10% organic matter, are also associated with lower reflectance values. The organic matter, although not fully characterized by type, correlates strongly with metals (e.g., Cu, Pb, As, Cd, Mo, Zn) derived from distal urban and industrial settings, probably including mining and smelting sites. This relation suggests anthropogenic sources for at least some of the carbonaceous matter, such as emissions from transportation and industrial activities. The composition of the DOS samples can be compared with sediments in a likely dust-source setting at the Milford Flat Fire (MFF) area about 225

  14. Composition of dust deposited to snow cover in the Wasatch Range (Utah, USA): Controls on radiative properties of snow cover and comparison to some dust-source sediments

    Science.gov (United States)

    Reynolds, Richard L.; Goldstein, Harland L.; Moskowitz, Bruce M.; Bryant, Ann C.; Skiles, S. McKenzie; Kokaly, Raymond F.; Flagg, Cody B.; Yauk, Kimberly; Berquó, Thelma; Breit, George; Ketterer, Michael; Fernandez, Daniel; Miller, Mark E.; Painter, Thomas H.

    2014-12-01

    Dust layers deposited to snow cover of the Wasatch Range (northern Utah) in 2009 and 2010 provide rare samples to determine the relations between their compositions and radiative properties. These studies are required to comprehend and model how such dust-on-snow (DOS) layers affect rates of snow melt through changes in the albedo of snow surfaces. We evaluated several constituents as potential contributors to the absorption of solar radiation indicated by values of absolute reflectance determined from bi-conical reflectance spectroscopy. Ferric oxide minerals and carbonaceous matter appear to be the primary influences on lowering snow-cover albedo. Techniques of reflectance and Mössbauer spectroscopy as well as rock magnetism provide information about the types, amounts, and grain sizes of ferric oxide minerals. Relatively high amounts of ferric oxide, indicated by hard isothermal remanent magnetization (HIRM), are associated with relatively low average reflectance (iron oxide control on absorption of solar radiation. At least some goethite occurs as nano-phase grain coatings less than about 50 nm thick. Relatively high amounts of organic carbon, indicating as much as about 10% organic matter, are also associated with lower reflectance values. The organic matter, although not fully characterized by type, correlates strongly with metals (e.g., Cu, Pb, As, Cd, Mo, Zn) derived from distal urban and industrial settings, probably including mining and smelting sites. This relation suggests anthropogenic sources for at least some of the carbonaceous matter, such as emissions from transportation and industrial activities. The composition of the DOS samples can be compared with sediments in a likely dust-source setting at the Milford Flat Fire (MFF) area about 225 km southwest of Salt Lake City. The MFF area represents geologically and physiographically similar and widespread dust sources west-southwest of the Wasatch Range and heavily populated Wasatch Front. The DOS

  15. M-Band Spectra of Dust Embedded Sources at the Galactic Center

    CERN Document Server

    Moultaka, J; Schödel, R

    2009-01-01

    The goal of the present paper is to investigate the circumstellar material around the brightest dust-enshrouded sources in the central stellar cluster of the Milky Way. Observations have been carried out at the European Southern Observatory's Very Large Telescope on Paranal, Chile. We have used the long wavelength (LWS3) low resolution (LR) spectroscopic mode of the ISAAC camera at the VLT in the spectral range of the M filter from 4.4micron to 5.1micron. The use of a slit width of 0.6" implied a spectral resolution of R=l/Dl=800 (Dv=375 km/s). These observations resulted in M-band spectra of 15 bright sources in the central stellar cluster of the Milky Way. In addition to gaseous 12^CO (4.666 micron) and 13^CO (4.77 micron) vibration-rotational absorptions, we detect a strong absorption due to a mixture of polar and apolar CO ice (centered at 4.675 micron). In the shorter wavelength absorption wing there is an absorption feature due to XCN at 4.62 micron. The XCN absorption is strongest toward the M2 supergi...

  16. Herschel-ATLAS: Dust Temperature and Redshift Distribution of SPIRE and PACS Detected Sources Using Submillimetre Colours

    Science.gov (United States)

    Amblard, A.; Cooray, Asantha; Serra, P.; Temi, P.; Barton, E.; Negrello, M.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A.; Bock, J.; Bonfield, D.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D.; Croom, S.; Dariush, A.; deZotti, G.; Driver, S.; Dunlop, J.; Dunne, L.; Dye, S.

    2010-01-01

    We present colour-colour diagrams of detected sources in the Herschel-ATLAS Science Demonstration Field from 100 to 500/microns using both PACS and SPIRE. We fit isothermal modified-blackbody spectral energy distribution (SED) models in order to extract the dust temperature of sources with counterparts in GAMA or SDSS with either a spectroscopic or a photometric redshift. For a subsample of 331 sources detected in at least three FIR bands with significance greater than 30 sigma, we find an average dust temperature of (28 plus or minus 8)K. For sources with no known redshifts, we populate the colour-colour diagram with a large number of SEDs generated with a broad range of dust temperatures and emissivity parameters and compare to colours of observed sources to establish the redshift distribution of those samples. For another subsample of 1686 sources with fluxes above 35 mJy at 350 microns and detected at 250 and 500 microns with a significance greater than 3sigma, we find an average redshift of 2.2 plus or minus 0.6.

  17. A novel integrated approach for the hazardous radioactive dust source terms estimation in future nuclear fusion power plants.

    Science.gov (United States)

    Poggi, L A; Malizia, A; Ciparisse, J F; Gaudio, P

    2016-10-01

    An open issue still under investigation by several international entities working on the safety and security field for the foreseen nuclear fusion reactors is the estimation of source terms that are a hazard for the operators and public, and for the machine itself in terms of efficiency and integrity in case of severe accident scenarios. Source term estimation is a crucial key safety issue to be addressed in the future reactors safety assessments, and the estimates available at the time are not sufficiently satisfactory. The lack of neutronic data along with the insufficiently accurate methodologies used until now, calls for an integrated methodology for source term estimation that can provide predictions with an adequate accuracy. This work proposes a complete methodology to estimate dust source terms starting from a broad information gathering. The wide number of parameters that can influence dust source term production is reduced with statistical tools using a combination of screening, sensitivity analysis, and uncertainty analysis. Finally, a preliminary and simplified methodology for dust source term production prediction for future devices is presented.

  18. Untangling the nature of spatial variations of cold dust properties in star forming galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, Allison; Calzetti, Daniela [Department of Astronomy, University of Massachusetts, Amherst, MA 01002 (United States); Kennicutt, Robert [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Galametz, Maud [European Southern Observatory, Karl-Schwarzchild-Str. 2, D-85748 Garching-bei-München (Germany); Gordon, Karl [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Groves, Brent; Tabatabaei, Fatemeh [Max-Planck Institut für Astronomie, Königstuhl 17, D-69117, Heidelberg (Germany); Hunt, Leslie [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Dale, Daniel [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Hinz, Joannah, E-mail: kirkpatr@astro.umass.edu [MMT Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States)

    2014-07-10

    We investigate the far-infrared (IR) dust emission for 20 local star forming galaxies from the Key Insights on Nearby Galaxies: A Far-IR Survey with Herschel (KINGFISH) sample. We model the far-IR/submillimeter spectral energy distribution (SED) using images from Spitzer Space Telescope and Herschel Space Observatory. We calculate the cold dust temperature (T{sub c} ) and emissivity (β) on a pixel by pixel basis (where each pixel ranges from 0.1 to 3 kpc{sup 2}) using a two-temperature modified blackbody fitting routine. Our fitting method allows us to investigate the resolved nature of temperature and emissivity variations by modeling from the galaxy centers to the outskirts (physical scales of ∼15-50 kpc, depending on the size of the galaxy). We fit each SED in two ways: (1) fit T{sub c} and β simultaneously, (2) hold β constant and fit T{sub c} . We compare T{sub c} and β with star formation rates (calculated from L{sub Hα} and L{sub 24μm}), the luminosity of the old stellar population (traced through L{sub 3.6μm}), and the dust mass surface density (traced by 500 μm luminosity, L{sub 500}). We find a significant trend between SFR/L{sub 500} and T{sub c} , implying that the flux of hard UV photons relative to the amount of dust is significantly contributing to the heating of the cold, or diffuse, dust component. We also see a trend between L{sub 3.6}/L{sub 500} and β, indicating that the old stellar population contributes to the heating at far-IR/submillimeter wavelengths. Finally, we find that when β is held constant, T{sub c} exhibits a strongly decreasing radial trend, illustrating that the shape of the far-IR SED is changing radially through a galaxy, thus confirming on a sample almost double in size the trends observed in Galametz et al.

  19. Mineral dust transport in the Arctic modelled with FLEXPART

    Science.gov (United States)

    Groot Zwaaftink, Christine; Grythe, Henrik; Stohl, Andreas

    2016-04-01

    Arctic atmosphere is dominated by dust from Africa and Asia. However, in the lower atmosphere, local sources also contribute strongly to dust concentrations. Especially from Iceland, significant amounts of dust are mobilized. These local sources with relatively shallow transport of dust also affect the spatial distribution of dust deposition. For instance, model estimates show that in autumn and winter most of the deposited dust in Greenland originates from sources north of 60 degrees latitude.

  20. Tracing Sources and Contamination Assessments of Heavy Metals in Road and Foliar Dusts in a Typical Mining City, China

    Science.gov (United States)

    Yang, Jie; Teng, Yanguo; Song, Liuting; Zuo, Rui

    2016-01-01

    Road and foliar dust samples from four land-use districts of Panzhihua City, a famous V-Ti magnetite production area of China, were collected to investigate the sources and distribution characteristics of 9 heavy metals (V, Pb, Cd, Cu, Zn, Ni, Cr, Fe, and Mn). The results suggest that foliar samples had smaller particle size and higher heavy metal contents than road dusts. The contamination assessments of heavy metals were as follows: Pb and V (significant enrichment) > Zn, Ni, Cr, Fe, and Mn (moderate enrichment) > Cd and Ni (minimal enrichment). Statistical analyses showed Pb, as the primary pollution element, originated from waste incineration and lead-fuel combustion. The sources of Zn, Ni, Cr, Fe, V, and Mn were fugitive dust and traffic activities. Potential origins of Cu were corrosion of alloys used in vehicle components, vehicle covers, or other metallic surfaces and materials. The sources of Cd were different from any other heavy metals. Traffic and industrial activities were the main anthropogenic origins of heavy metals in dusts of Panzhihua, and more attention should be paid to heavy metal pollution in agricultural area. PMID:27992518

  1. Characterization of PM 10 and PM 2.5 source profiles for fugitive dust in Hong Kong

    Science.gov (United States)

    Ho, K. F.; Lee, S. C.; Chow, Judith C.; Watson, John G.

    PM 10 and PM 2.5 chemical source profiles from Hong Kong were investigated for paved road dust and soil. These profiles are needed for urban-scale speciated emissions inventories and for source apportionment by receptor modeling. Five urban soil and five paved road dust samples were collected, dried and sieved, resuspended in a laboratory chamber, air drawn through PM 10 and PM 2.5 inlet onto Teflon and quartz filters. The filter samples were submitted for both gravimetric and chemical analyses. Chemical analyses included X-ray fluorescence for elemental composition, ion chromatography for water soluble chloride, nitrate, sulfate, atomic absorption spectrophotometry for water soluble sodium and potassium, automated colorimetric analysis for ammonium and thermal/optical reflectance analysis for carbon species. The PM 2.5 constituted 11-30% of the PM 10 in all geological samples. Al, Si and organic carbon (OC) are abundant constituents in all paved road dust and soil samples. The chemical abundances of PM 2.5 and PM 10 for a given source type were similar for most species. In addition, results from resuspended soil (three sets), paved road dust (five sets), aggregate (three sets) and cement (two sets) were obtained from Hong Kong Environmental Protection Department (HKEPD) for comparison as well as mass closure analysis.

  2. Status, source and health risk assessment of polycyclic aromatic hydrocarbons in street dust of an industrial city, NW China.

    Science.gov (United States)

    Jiang, Yufeng; Hu, Xuefei; Yves, Uwamungu J; Zhan, Huiying; Wu, Yingqin

    2014-08-01

    The status, source and health risk of street-dust-borne polycyclic aromatic hydrocarbons (PAHs) in Lanzhou of Northwest China were investigated. The total level of the 21 PAHs ranged from 1470 to 13,700 µg kg(-1) and that of the 16 priority PAHs from 1240 to 10,700 µg kg(-1). Higher levels of PAHs were mainly distributed in the Chengguan and Qilihe districts at Lanzhou central areas, and the lower levels were in Anning and Xigu districts. The level of seven potential carcinogenic PAHs generally accounted for 35-40 percent of total PAHs, and the PAHs contained two to four rings, mainly phenanthrene, benzo[b]fluoranthene and fluoranthene. The total level of PAHs increased with the decreasing particle size in the street dust. The correlation analysis suggested that the total organic carbon (TOC) was only slightly affected the PAH accumulation in street dust. The isomer ratios and principal component analysis indicated that the dust-borne PAHs in the dust were derived primarily from the combustion of biomass, coal and petroleum emission. The toxic equivalent concentrations (BaP(eq)) of dust-borne PAHs ranged from 115 to 827 µg BaP(eq) kg(-1), with a mean of 300 µg BaP(eq) kg(-1). The 95 percent upper confidence limit of Incremental Lifetime Cancer Risk due to human exposure to urban surface dust-borne PAHs in Lanzhou urban area was 2.031 × 10(-6) for children and 1.935 × 10(-6) for adults.

  3. House dust mites: a risk factor to be considered for occupational safety or source of work-related allergens.

    Science.gov (United States)

    Saleh, Ahmed Megahed Ahmed; Ali, Hisham Abd El-Raouf; Ahmed, Salwa Abdalla Mohamed; Mohammad, Naema Mahmoud; Morsy, Tosson A

    2013-12-01

    House dust mites (HDM) can be found worldwide where human beings live independent from the climate and are a major source of multiple allergens. Mite allergens sensitize and induce perennial rhinitis, asthma, or atopic dermatitis in a large portion of patients with allergic disease particularly children. There is convincing evidence that avoidance of mite allergen can effectively reduce allergic symptoms. This study examined dust from a military hospital and the private home of some nursing staff. A total of seven species of mites belonging to six genera were recovered. The commonest species was Dermatophagoides farinae followed by D. pteronyssinus and the lowest Laelaps nuttalli. Besides, the 7th mite or Parasitus consanguineous live free on dust as a bio-control agent of mites. The presence of mites in and out doors in a hospital and dwellings of medical personnel pave the way to consider HDM as occupational or nosocomial Allergens.

  4. SPATIAL DMBS ARCHITECTURE FOR A FREE AND OPEN SOURCE BIM

    Directory of Open Access Journals (Sweden)

    S. Logothetis

    2017-08-01

    Full Text Available Recent research on the field of Building Information Modelling (BIM technology, revealed that except of a few, accessible and free BIM viewers there is a lack of Free & Open Source Software (FOSS BIM software for the complete BIM process. With this in mind and considering BIM as the technological advancement of Computer-Aided Design (CAD systems, the current work proposes the use of a FOSS CAD software in order to extend its capabilities and transform it gradually into a FOSS BIM platform. Towards this undertaking, a first approach on developing a spatial Database Management System (DBMS able to store, organize and manage the overall amount of information within a single application, is presented.

  5. Spatial Dmbs Architecture for a Free and Open Source Bim

    Science.gov (United States)

    Logothetis, S.; Valari, E.; Karachaliou, E.; Stylianidis, E.

    2017-08-01

    Recent research on the field of Building Information Modelling (BIM) technology, revealed that except of a few, accessible and free BIM viewers there is a lack of Free & Open Source Software (FOSS) BIM software for the complete BIM process. With this in mind and considering BIM as the technological advancement of Computer-Aided Design (CAD) systems, the current work proposes the use of a FOSS CAD software in order to extend its capabilities and transform it gradually into a FOSS BIM platform. Towards this undertaking, a first approach on developing a spatial Database Management System (DBMS) able to store, organize and manage the overall amount of information within a single application, is presented.

  6. Spatial data integration from distributed and heterogeneous sources

    Directory of Open Access Journals (Sweden)

    Genoveva Vargas S.

    2004-01-01

    Full Text Available El presente trabajo discute los retos asociados a la integración de datos espaciales y presenta el enfoque adoptado en el proyecto SPIDHERS (SPatial data Integraction from Distributed and HEteRogeneous Sources – Integración de Datos Espaciales a partir de Fuentes Heterogéneas y Distribuidas basado en técnicas de mediación, recuperación, análisis y extracción eficientes de datos. Finalmente, este trabajo muestra la forma en que se puede utilizar la tecnología producida en SPIDHERS para integrar, analizar y tomar decisiones utilizando datos del Popocatépetl, volcán ubicado en la región de Puebla y la Ciudad de México.

  7. Urban dust in the Guanzhong basin of China, part II: A case study of urban dust pollution using the WRF-Dust model.

    Science.gov (United States)

    Li, Nan; Long, Xin; Tie, Xuexi; Cao, Junji; Huang, Rujin; Zhang, Rong; Feng, Tian; Liu, Suixin; Li, Guohui

    2016-01-15

    We developed a regional dust dynamical model (WRF-Dust) to simulate surface dust concentrations in the Guanzhong (GZ) basin of China during two typical dust cases (19th Aug. and 26th Nov., 2013), and compared model results with the surface measurements at 17 urban and rural sites. The important improvement of the model is to employ multiple high-resolution (0.5-500 m) remote sensing data to construct dust sources. The new data include the geographic information of constructions, croplands, and barrens over the GZ basin in summer and winter of 2013. For the first time, detailed construction dust emissions have been introduced in a regional dust model in large cities of China. Our results show that by including the detailed dust sources, model performance at simulating dust pollutions in the GZ basin is significantly improved. For example, the simulated dust concentration average for the 17 sites increases from 28 μg m(-3) to 59 μg m(-3), closing to the measured concentration of 66 μg m(-3). In addition, the correlation coefficient (r) between the calculated and measured dust concentrations is also improved from 0.17 to 0.57, suggesting that our model better presents the spatial variation. Further analysis shows that urban construction activities are the crucial source in controlling urban dust pollutions. It should be considered by policy makers for mitigating particulate air pollution in many Chinese cities.

  8. Spatial variability and sources of ammonia in three European cities

    Science.gov (United States)

    Prevot, Andre S. H.; Elser, Miriam; El Haddad, Imad; Maasikmets, Marek; Bozzetti, Carlo; Robert, Wolf; Richter, Rene; Slowik, Jay; Teinemaa, Erik; Hueglin, Christoph; Baltensperger, Urs

    2017-04-01

    For the assessment of ammonia (NH3) effects on ecosystems and climate, one would ideally know the emission sources and also the spatial distributions. Agriculture is the largest global source of NH3. However traffic, especially gasoline vehicles, biomass burning or waste management can be significant in urban areas. Ambient NH3 measurements using cavity ring-down spectroscopy were performed online at high time resolution on a moving vehicle in three cities: Zurich (Switzerland), Tartu (Estonia) and Tallinn (Estonia). Initial tests showed that a regular inlet cannot be used. A heated line including an auxiliary flow was finally deployed to minimize NH3 adsorption onto the inlet walls. We will present the characterization of the response and recovery times of the measurement system which was used to deconvolve the true NH3 signal from the remaining adsorption-induced hysteresis. Parallel measurements with an Aerodyne aerosol mass spectrometer were used to correct the observed NH3 for the contribution of ammonium nitrate (NH4NO3) which completely evaporated to NH3 and nitric acid (HNO3) in the heated line at the chosen temperature, in contrast to ammonium sulfate. Finally, quantitative measurements of ambient NH3 are possible with sufficient time resolution to enable measurement of NH3 point or line sources with a mobile sampling platform. The NH3 analyzer and the aerosol mass spectrometer were complemented by an aethalometer to measure black carbon and various gas-phase analyzers to enable a complete characterization of the sources of air pollution, including the spatial distributions and the regional background concentrations and urban increments of all measured components. Although at all three locations similar urban increment levels of organic aerosols were attributed to biomass burning and traffic, traffic emissions clearly dominated the city enhancements of NH3, equivalent black carbon (eBC) and carbon dioxide (CO2). Concentration gradients in areas strongly

  9. Polycyclic aromatic hydrocarbons (PAHs) in indoor dusts of Guizhou, southwest of China: status, sources and potential human health risk.

    Science.gov (United States)

    Yang, Qin; Chen, Huaguo; Li, Baizhan

    2015-01-01

    Polycyclic aromatic hydrocarbons (PAHs) were analyzed for 136 indoor dust samples collected from Guizhou province, southwest of China. The ∑18PAHs concentrations ranged from 2.18 μg•g-1 to 14.20 μg•g-1 with the mean value of 6.78 μg•g-1. The highest Σ18PAHs concentration was found in dust samples from orefields, followed by city, town and village. Moreover, the mean concentration of Σ18PAHs in indoor dust was at least 10% higher than that of outdoors. The 4-6 rings PAHs, contributing more than 70% of ∑18PAHs, were the dominant species. PAHs ratios, principal component analysis with multiple linear regression (PCA-MLR) and hierarchical clustering analysis (HCA) were applied to evaluate the possible sources. Two major origins of PAHs in indoor dust were identified as vehicle emissions and coal combustion. The mean incremental lifetime cancer risk (ILCR) due to human exposure to indoor dust PAHs in city, town, village and orefield of Guizhou province, China was 6.14×10-6, 5.00×10-6, 3.08×10-6, 6.02×10-6 for children and 5.92×10-6, 4.83×10-6, 2.97×10-6, 5.81×10-6 for adults, respectively.

  10. Polycyclic aromatic hydrocarbons (PAHs in indoor dusts of Guizhou, southwest of China: status, sources and potential human health risk.

    Directory of Open Access Journals (Sweden)

    Qin Yang

    Full Text Available Polycyclic aromatic hydrocarbons (PAHs were analyzed for 136 indoor dust samples collected from Guizhou province, southwest of China. The ∑18PAHs concentrations ranged from 2.18 μg•g-1 to 14.20 μg•g-1 with the mean value of 6.78 μg•g-1. The highest Σ18PAHs concentration was found in dust samples from orefields, followed by city, town and village. Moreover, the mean concentration of Σ18PAHs in indoor dust was at least 10% higher than that of outdoors. The 4-6 rings PAHs, contributing more than 70% of ∑18PAHs, were the dominant species. PAHs ratios, principal component analysis with multiple linear regression (PCA-MLR and hierarchical clustering analysis (HCA were applied to evaluate the possible sources. Two major origins of PAHs in indoor dust were identified as vehicle emissions and coal combustion. The mean incremental lifetime cancer risk (ILCR due to human exposure to indoor dust PAHs in city, town, village and orefield of Guizhou province, China was 6.14×10-6, 5.00×10-6, 3.08×10-6, 6.02×10-6 for children and 5.92×10-6, 4.83×10-6, 2.97×10-6, 5.81×10-6 for adults, respectively.

  11. Iron oxide minerals in dust-source sediments from the Bodélé Depression, Chad: Implications for radiative properties and Fe bioavailability of dust plumes from the Sahara

    Science.gov (United States)

    Moskowitz, Bruce M.; Reynolds, Richard L.; Goldstein, Harland L.; Berquó, Thelma S.; Kokaly, Raymond F.; Bristow, Charlie S.

    2016-09-01

    Atmospheric mineral dust can influence climate and biogeochemical cycles. An important component of mineral dust is ferric oxide minerals (hematite and goethite) which have been shown to influence strongly the optical properties of dust plumes and thus affect the radiative forcing of global dust. Here we report on the iron mineralogy of dust-source samples from the Bodélé Depression (Chad, north-central Africa), which is estimated to be Earth's most prolific dust producer and may be a key contributor to the global radiative budget of the atmosphere as well as to long-range nutrient transport to the Amazon Basin. By using a combination of magnetic property measurements, Mössbauer spectroscopy, reflectance spectroscopy, chemical analysis, and scanning electron microscopy, we document the abundance and relative amounts of goethite, hematite, and magnetite in dust-source samples from the Bodélé Depression. The partition between hematite and goethite is important to know to improve models for the radiative effects of ferric oxide minerals in mineral dust aerosols. The combination of methods shows (1) the dominance of goethite over hematite in the source sediments, (2) the abundance and occurrences of their nanosize components, and (3) the ubiquity of magnetite, albeit in small amounts. Dominant goethite and subordinate hematite together compose about 2% of yellow-reddish dust-source sediments from the Bodélé Depression and contribute strongly to diminution of reflectance in bulk samples. These observations imply that dust plumes from the Bodélé Depression that are derived from goethite-dominated sediments strongly absorb solar radiation. The presence of ubiquitous magnetite (0.002-0.57 wt%) is also noteworthy for its potentially higher solubility relative to ferric oxide and for its small sizes, including PM bioavailability to marine and terrestrial ecosystems.

  12. Spatial and Temporal Variation of the Extreme Saharan Dust Event over Turkey in March 2016

    Directory of Open Access Journals (Sweden)

    Hakki Baltaci

    2017-02-01

    Full Text Available In this study, the influence of an extraordinary Saharan dust episode over Turkey on 23–24 March 2016 and the atmospheric conditions that triggered this event were evaluated in detail. PM10 (particulate matter less than 10 μm observations from 97 air quality stations, METAR (Meteorological Terminal Aviation Routine Weather Report observations at 64 airports, atmospheric soundings, and satellite products were used for the analysis. To determine the surface and upper levels of atmospheric circulation, National Centers of Environmental Prediction (NCEP/National Center for Atmospheric Research (NCAR Reanalysis data were applied to the extreme dust episodes. On 23 March 2016, high southwesterly winds due to the interaction between surface low- and high-pressure centers over Italy and Levant basin brought thick dust particles from Libya to Turkey. The daily PM10 data from 43 stations exceeded their long-term spring means over Turkey (especially at the northern and western stations. As a consequence of the longitudinal movement of the surface low from Italy to the Balkan Peninsula, and the quasi-stationary conditions of the surface high-pressure center allowed for the penetration of strong south and southwesterly winds to inner parts of the country on the following day. As a consequence, 100%, 90%, 88%, and 87% of the monitoring stations in Marmara (NW Turkey, central Anatolia, western (Aegean and northern (Black Sea regions of Turkey, respectively, exhibited above-normal daily PM10 values. In addition, while strong subsidence at the low levels of the atmosphere plays a significant role in having excessive daily PM10 values in Black Sea, dry atmospheric conditions and thick inversion level near the ground surface of Marmara ensured this region to have peak PM10 values ~00 Local Time (LT.

  13. Laboratory study of PCB transport from primary sources to settled dust

    Science.gov (United States)

    Transport of house dust and Arizona Test Dust on polychlorinated biphenyl (PCB)-containing panels and PCB-free panels was investigated in a 30-m3 stainless steel chamber. The PCB-containing panels were aluminum sheets coated with a PCB-spiked, oil-based primer or two-part polysul...

  14. Distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in street dust from the Tokyo Metropolitan area.

    Science.gov (United States)

    Takada, H; Onda, T; Harada, M; Ogura, N

    1991-09-01

    Molecular distributions of polycyclic aromatic hydrocarbons (PAHs) in street dust samples collected from the Tokyo Metropolitan area were determined by capillary gas chromatography following HPLC fractionation. Three- to six-ring PAHs and sulfur-heterocyclics were detected. PAHs in the dusts were dominated by three and four unsubstituted ring systems with significant amounts of their alkyl homologues. PAHs were widely distributed in the streets, with concentrations (sigma COMB) of a few microgram/g dust. Automobile exhaust, asphalt, gasoline fuel, diesel fuel, tyre particles, automobile crankcase oils, and atmospheric fallout were also analysed. The PAH profile, especially the relative abundance of alkyl-PAHs and sulfur-containing heterocyclics, indicated that PAHs in the street dusts from roads carrying heavy traffic are mainly derived from automobile exhausts; dusts from residential areas have a more significant contribution from atmospheric fallout.

  15. Characterization of alluvial dust sources and their temporal development - a multi-sensor approach for the Aïr Massif, Niger

    Science.gov (United States)

    Feuerstein, Stefanie; Schepanski, Kerstin

    2017-04-01

    One of the world's largest sources of atmospheric dust is the Sahara. It is said that 55% of the total global dust emission can be linked to the desert in northern Africa. Thus, understanding the Saharan dust sources is of great importance to estimate the total global dust load and its variability. Especially one type of dust sources has gained attention in dust research in recent years: The emission of dust from sediments formed by hydrologic processes, so called alluvial dust sources. These sediments were either formed in the past under the influences of a more humid paleoclimate or are deposited recently, e.g. during strong precipitation events when surficial runoff leads to the activation of wadi systems or to the occurrence of flash floods. Especially the latter phenomenon is able to deliver a huge amount of potentially erodible sediments. The research presented here focuses on the characterization of these alluvial dust sources with special attention on their temporal variability in relation to wet and dry phases. A study area covering the Aïr Massif in Niger is analysed over a four years time span from January 2013 to December 2016. The whole cycle from sediment formation to dust emission is illustrated by using data of various satellite sensors that are able to capture the processes taking place at the land surface as well as in the atmosphere: (1) The rainfall distribution for the study area is shown by time series of the TRMM precipitation estimates. A catchment analysis of the area helps to estimate the amount of surficial runoff and to detect areas of potential sediment accumulation. (2) Changes in the sediment structure of the land surface are analysed using atmospherically corrected time series of NASA's Landsat-8 OLI satellite. A land cover classification shows the distribution of alluvial sediments over the area; fresh layers of alluvial deposits are detected. Furthermore, the evolution of the vegetation cover, which inhibits dust emission, is

  16. Technical Note: High-resolution mineralogical database of dust-productive soils for atmospheric dust modeling

    Directory of Open Access Journals (Sweden)

    S. Nickovic

    2012-01-01

    Full Text Available Dust storms and associated mineral aerosol transport are driven primarily by meso- and synoptic-scale atmospheric processes. It is therefore essential that the dust aerosol process and background atmospheric conditions that drive dust emissions and atmospheric transport are represented with sufficiently well-resolved spatial and temporal features. The effects of airborne dust interactions with the environment determine the mineral composition of dust particles. The fractions of various minerals in aerosol are determined by the mineral composition of arid soils; therefore, a high-resolution specification of the mineral and physical properties of dust sources is needed.

    Several current dust atmospheric models simulate and predict the evolution of dust concentrations; however, in most cases, these models do not consider the fractions of minerals in the dust. The accumulated knowledge about the impacts of the mineral composition in dust on weather and climate processes emphasizes the importance of including minerals in modeling systems. Accordingly, in this study, we developed a global dataset consisting of the mineral composition of the current potentially dust-producing soils. In our study, we (a mapped mineral data to a high-resolution 30 s grid, (b included several mineral-carrying soil types in dust-productive regions that were not considered in previous studies, and (c included phosphorus.

  17. Influence of quarry mining dust on PM2.5 in a city adjacent to a limestone quarry: Seasonal characteristics and source contributions.

    Science.gov (United States)

    Peng, Xing; Shi, Guo-Liang; Zheng, Jun; Liu, Jia-Yuan; Shi, Xu-Rong; Xu, Jiao; Feng, Yin-Chang

    2016-04-15

    To understand the influence of quarry mining dust on particulate matter, ambient PM2.5 and quarry mining dust source samples were collected in a city near quarry facilities during 2013-2014. Samples were subject to chemical analysis for dust-related species (Al, Si, Ca, Fe, Ti), tracer metals, carbon components and water-soluble ions. Seasonal variations of PM2.5 and its main chemical components were investigated. Distinctive seasonal variations of PM2.5 were observed, with the highest PM2.5 concentrations (112.42μgm(-3)) in fall and lowest concentrations in summer (45.64μgm(-3)). For dust-related species, mass fractions of Si and Al did not show obvious seasonal variations, whereas Ca presented higher fractions in spring and summer and lower fractions in fall and winter. A combined receptor model (PMF-CMB) was applied to quantify the quarry mining dust contribution to PM2.5. Seven sources were identified, including quarry mining dust, soil dust, cement dust, coal combustion vehicles, secondary sulfate and secondary nitrate. On a yearly average basis, the contribution of quarry mining dust to PM2.5 was 6%. The contribution of soil dust to PM2.5 was comparable with cement dust (13% and 13%, respectively). Other identified sources included vehicle, secondary sulfate, secondary nitrate and coal combustion, which contributed 23, 15, 9 and 18% of the total mass, respectively. Air mass residence time (AMRT) analysis showed that northeast and southeast regions might be the major PM2.5 source during the sampling campaign. The findings of this study can be used to understand the characteristics of quarry mining dust and control strategies for PM2.5.

  18. HST Morphologies of z ~ 2 Dust-Obscured Galaxies II: Bump Sources

    CERN Document Server

    Bussmann, R S; Lotz, J; Armus, L; Brown, M J I; Desai, V; Eisenhardt, P; Higdon, J; Higdon, S; Jannuzi, B T; Floc'h, E Le; Melbourne, J; Soifer, B T; Weedman, D

    2011-01-01

    We present Hubble Space Telescope (HST) imaging of 22 ultra-luminous infrared galaxies (ULIRGs) at z~2 with extremely red R-[24] colors (called dust-obscured galaxies, or DOGs) which have a local maximum in their spectral energy distribution (SED) at rest-frame 1.6um associated with stellar emission. These sources, which we call "bump DOGs", have star-formation rates of 400-4000 Msun/yr and have redshifts derived from mid-IR spectra which show strong polycyclic aromatic hydrocarbon emission --- a sign of vigorous on-going star-formation. Using a uniform morphological analysis, we look for quantifiable differences between bump DOGs, power-law DOGs (Spitzer-selected ULIRGs with mid-IR SEDs dominated by a power-law and spectral features that are more typical of obscured active galactic nuclei than starbursts), sub-millimeter selected galaxies (SMGs), and other less-reddened ULIRGs from the Spitzer extragalactic First Look Survey (XFLS). Bump DOGs are larger than power-law DOGs (median Petrosian radius of 8.4 +/-...

  19. Source, distribution, and health risk assessment of polycyclic aromatic hydrocarbons in urban street dust from Tianjin, China.

    Science.gov (United States)

    Yu, Binbin; Xie, Xiujie; Ma, Lena Q; Kan, Haidong; Zhou, Qixing

    2014-02-01

    To better assess and understand potential health risk of urban residents exposed to urban street dust, the total concentration, sources, and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in 87 urban street dust samples from Tianjin as a Chinese megacity that has undergone rapid urbanization were investigated. In the meantime, potential sources of PAHs were identified using the principal component analysis (PCA), and the risk of residents' exposure to PAHs via urban street dust was calculated using the Incremental Lifetime Cancer Risk (ILCR) model. The results showed that the total PAHs (∑PAHs) in urban street dust from Tianjin ranged from 538 μg kg(-1) to 34.3 mg kg(-1), averaging 7.99 mg kg(-1). According to PCA, the two to three- and four to six-ring PAHs contributed 10.3 and 89.7 % of ∑PAHs, respectively. The ratio of the sum of major combustion specific compounds (ΣCOMB) / ∑PAHs varied from 0.57 to 0.79, averaging 0.64. The ratio of Ant/(Ant + Phe) varied from 0.05 to 0.41, averaging 0.10; Fla/(Fla + Pyr) from 0.40 to 0.68, averaging 0.60; BaA/(BaA + Chry) from 0.29 to 0.51, averaging 0.38; and IcdP/(IcdP + BghiP) from 0.07 to 0.37, averaging 0.22. The biomass combustion, coal combustion, and traffic emission were the main sources of PAHs in urban street dust with the similar proportion. According to the ILCR model, the total cancer risk for children and adults was up to 2.55 × 10(-5) and 9.33 × 10(-5), respectively.

  20. Untangling the Nature of Spatial Variations of Cold Dust Properties in Star Forming Galaxies

    CERN Document Server

    Kirkpatrick, Allison; Kennicutt, Robert; Galametz, Maud; Gordon, Karl; Groves, Brent; Hunt, Leslie; Dale, Daniel; Hinz, Joannah; Tabatabaei, Fatemeh

    2014-01-01

    We investigate the far-infrared (IR) dust emission for 20 local star forming galaxies from the Key Insights on Nearby Galaxies: A Far-IR Survey with Herschel (KINGFISH) sample. We model the far-IR/submillimeter spectral energy distribution (SED) using images from Spitzer Space Telescope and Herschel Space Observatory. We calculate the cold dust temperature (T(cold)) and emissivity (beta) on a pixel by pixel basis (where each pixel ranges from 0.1-3 kpc^2) using a two temperature modified blackbody fitting routine. Our fitting method allows us to investigate the resolved nature of temperature and emissivity variations by modeling from the galaxy centers to the outskirts (physical scales of ~15-50 kpc, depending on the size of the galaxy). We fit each SED in two ways: (1) fit T(cold) and beta simultaneously, (2) hold beta constant and fit T(cold). We compare T(cold) and beta with star formation rates (calculated from L(Halpha) and L(24)), the luminosity of the old stellar population (traced through L(3.6), and ...

  1. THE EVOLUTION OF DUST IN THE MAGELLANIC CLOUDS

    Science.gov (United States)

    Dwek, Eli; Temim, T.; Meixner, M.; Boyer, M. L.; Tchernyshyov, K.; Gall, C.

    2014-01-01

    The Magellanic Clouds offer a unique astrophysical laboratory for studying the evolution of interstellar dust. They are the closest to the Milky Way with well determined distance, and they have been extensively studies at many different wavelength with sufficient spatial resolution to construct a detailed picture of the evolution of the dust in the diverse stellar and interstellar environments of these two galaxies. Using chemical evolution models for the dust I will present the formation rates of the dust in AGB stars and supernovae, and compare them to observations. The dust formation rates will then be compared to their observed rates of destruction by supernova remnants (see Temim, this meeting). The comparison will provide important information on the origin of dust in the Magellanic Clouds. Understanding the different stellar sources of dust and the processes leading to their destruction are essential for understanding the origin of dust in the Milky Way, in local galaxies, and the early universe as well.

  2. Spatial Information Processing: Standards-Based Open Source Visualization Technology

    Science.gov (United States)

    Hogan, P.

    2009-12-01

    . Spatial information intelligence is a global issue that will increasingly affect our ability to survive as a species. Collectively we must better appreciate the complex relationships that make life on Earth possible. Providing spatial information in its native context can accelerate our ability to process that information. To maximize this ability to process information, three basic elements are required: data delivery (server technology), data access (client technology), and data processing (information intelligence). NASA World Wind provides open source client and server technologies based on open standards. The possibilities for data processing and data sharing are enhanced by this inclusive infrastructure for geographic information. It is interesting that this open source and open standards approach, unfettered by proprietary constraints, simultaneously provides for entirely proprietary use of this same technology. 1. WHY WORLD WIND? NASA World Wind began as a single program with specific functionality, to deliver NASA content. But as the possibilities for virtual globe technology became more apparent, we found that while enabling a new class of information technology, we were also getting in the way. Researchers, developers and even users expressed their desire for World Wind functionality in ways that would service their specific needs. They want it in their web pages. They want to add their own features. They want to manage their own data. They told us that only with this kind of flexibility, could their objectives and the potential for this technology be truly realized. World Wind client technology is a set of development tools, a software development kit (SDK) that allows a software engineer to create applications requiring geographic visualization technology. 2. MODULAR COMPONENTRY Accelerated evolution of a technology requires that the essential elements of that technology be modular components such that each can advance independent of the other

  3. Herschel-ATLAS: Dust temperature and redshift distribution of SPIRE and PACS detected sources using submillimetre colours

    OpenAIRE

    Amblard, A.; Blain, A.; Bock, J.; Frayer, D; Vieira, J.

    2010-01-01

    We present colour–colour diagrams of detected sources in the Herschel-ATLAS science demonstration field from 100 to 500 μm using both PACS and SPIRE. We fit isothermal modified black bodies to the spectral energy distribution (SED) to extract the dust temperature of sources with counterparts in Galaxy And Mass Assembly (GAMA) or SDSS surveys with either a spectroscopic or a photometric redshift. For a subsample of 330 sources detected in at least three FIR bands with a significance greater th...

  4. Second-order spatial correlation in the far-field: Comparing entangled and classical light sources

    Science.gov (United States)

    Zhang, Erfeng; Liu, Weitao; Lin, Huizu; Chen, Pingxing

    2016-02-01

    We consider second-order spatial correlation with entangled and classical light in the far-field. The quantum theory of second-order spatial correlation is analyzed, and the role of photon statistics and detection mode in the second-order spatial correlation are discussed. Meanwhile, the difference of second-order spatial correlation with entangled and classical light sources is deduced.

  5. Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil.

    Science.gov (United States)

    Yu, Yang; Li, Yingxia; Li, Ben; Shen, Zhenyao; Stenstrom, Michael K

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources.

  6. Search for Spatially Extended Fermi-LAT Sources Using Two Years of Data

    CERN Document Server

    Lande, Joshua; Allafort, Alice; Ballet, Jean; Bechtol, Keith; Burnett, Toby; Cohen-Tanugi, Johann; Drlica-Wagner, Alex; Funk, Stefan; Giordano, Francesco; Grondin, Marie-Helene; Kerr, Matthew; Lemoine-Goumard, Marianne

    2012-01-01

    Spatial extension is an important characteristic for correctly associating gamma-ray-emitting sources with their counterparts at other wavelengths and for obtaining an unbiased model of their spectra. We present a new method for quantifying the spatial extension of sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi). We perform a series of Monte Carlo simulations to validate this tool and calculate the LAT threshold for detecting the spatial extension of sources. We then test all sources in the second Fermi-LAT catalog (2FGL) for extension. We report the detection of seven new spatially extended sources.

  7. Search for Spatially Extended Fermi-LAT Sources Using Two Years of Data

    Energy Technology Data Exchange (ETDEWEB)

    Lande, Joshua; Ackermann, Markus; Allafort, Alice; Ballet, Jean; Bechtol, Keith; Burnett, Toby; Cohen-Tanugi, Johann; Drlica-Wagner, Alex; Funk, Stefan; Giordano, Francesco; Grondin, Marie-Helene; Kerr, Matthew; Lemoine-Goumard, Marianne

    2012-07-13

    Spatial extension is an important characteristic for correctly associating {gamma}-ray-emitting sources with their counterparts at other wavelengths and for obtaining an unbiased model of their spectra. We present a new method for quantifying the spatial extension of sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi). We perform a series of Monte Carlo simulations to validate this tool and calculate the LAT threshold for detecting the spatial extension of sources. We then test all sources in the second Fermi -LAT catalog (2FGL) for extension. We report the detection of seven new spatially extended sources.

  8. Distributions, sources and pollution status of 17 trace metal/metalloids in the street dust of a heavily industrialized city of central China.

    Science.gov (United States)

    Li, Zhonggen; Feng, Xinbin; Li, Guanghui; Bi, Xiangyang; Zhu, Jianming; Qin, Haibo; Dai, Zhihui; Liu, Jinling; Li, Qiuhua; Sun, Guangyi

    2013-11-01

    A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution.

  9. [Distribution Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Dust of Xi'an City, China].

    Science.gov (United States)

    Wang, Li; Wang, Li-jun; Shi, Xing-min; Lu, Xin-wei

    2016-04-15

    A total of 58 surface dust samples were collected from Xi'an city. The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography with a flame ionization detector (GC-FID). At the same time, the distribution and sources of PAHs in surface dust were studied. The results showed that the concentrations of individual PAH ranged from 14.69 to 6370. 48 microg x kg(-1), and the total concentrations of 16 PAHs (∑16 PAHs) ranged from 5039.67 to 47,738.50 microg x kg(-1), with a mean of 13,845.82 microg x kg(-1). Compared to the Y PAHs levels of other cities, the ∑16 PAHs in surface dust of Xi'an belonged to a relatively higher level. PAHs in surface dust were mainly dominated by high molecular weight PAHs with 4-6 rings and the concentration of 7 carcinogenic PAHs (1 CPAHs) accounted for 46.08% of 3 16PAHs. The mean of ∑16 PAHs in surface dust had the highest concentration at industrial area; followed by the educational area, traffic area, business and traffic area; residential area and parks showed relatively lower concentration. The average content of ∑16 PAHs in surface dust presented an increasing trend along the main urban area--the second ring road--the third ring road. ∑16 PAHs in surface dust had higher concentrations at the industrial areas of the east and west suburbs of Xi'an, the south suburb and the north section of the second ring road; ∑16 PAHs concentrations in the main urban area, north suburb and southeast part of Xi'an were relatively lower. The results of ratio, cluster analysis and principal component analysis showed that PAHs in surface dust were mainly originated from the combustion of fossil fuels and coal combustion. Among them, diesel combustion reached 36.07%, gasoline combustion accounted for 32.31%, and coal combustion was resposbe for 23.40%

  10. Spatial variability of fine and coarse particle composition and sources in Cyprus

    Science.gov (United States)

    Achilleos, Souzana; Wolfson, Jack M.; Ferguson, Stephen T.; Kang, Choong-Min; Hadjimitsis, Diofantos G.; Hadjicharalambous, Marios; Achilleos, Constantia; Christodoulou, Andri; Nisanzti, Argyro; Papoutsa, Christiana; Themistocleous, Kyriacos; Athanasatos, Spyros; Perdikou, Skevi; Koutrakis, Petros

    2016-03-01

    Southern and Eastern European countries exceed WHO and EU air quality standards very often, and are influenced by both local and external sources from Europe, Asia and Africa. However, there are limited data on particle composition and source profiles. We collected PM2.5 and PM10 samples (particulate matter with aerodynamic diameter less than 2.5 and 10 μm, respectively) in four cities in Cyprus using Harvard Impactors. Measurements were conducted between January 2012 and January 2013. We analyzed these samples for mass concentration and chemical composition, and conducted a source apportionment analysis using Positive Matrix Factorization (PMF). All sites complied with PM2.5 and PM10 WHO daily standards for most of the days. As in other Eastern European countries, we found higher sulfate contribution and less organic carbon than in the Western and central Europe. For PM2.5, seven source types were identified including regional sulfur, traffic emissions, biomass, re-suspended soil, oil combustion, road dust, and sea salt. In all four sites, regional sulfur was the predominant source (> 30%). High inter-site correlations were observed for both PM2.5 component concentrations and source contributions, may be because a large fraction of PM2.5 is transported. Finally, for PM10 -2.5 (coarse particles with aerodynamic diameter between 2.5 and 10 μm) three sources were identified, which include road dust, soil, and sea salt. Significant inter-site correlations were also observed for coarse particles. All dust storm samples, except one, had PM levels below the daily standard. However, mineral dust, defined as the total mass of crustal metal oxides, increased up to ten times during the dust events.

  11. Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.

    Science.gov (United States)

    Chen, Haihan; Grassian, Vicki H

    2013-09-17

    Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.

  12. Upper Limit on Dimming of Cosmological Sources by Intergalactic Grey Dust from the Soft X-ray Background

    CERN Document Server

    Dijkstra, Mark

    2009-01-01

    Active Galactic Nuclei (AGN) produce a dominant fraction (~80%) of the Soft X-ray background (SXB) at photon energies 0.5dust pervaded throughout the intergalactic medium, its scattering opacity would have produced diffuse X-ray halos around AGN. Taking account of known galaxies and galaxy clusters, only a fraction F_halo <10% of the SXB can be in the form of diffuse X-ray halos around AGN. We therefore limit the intergalactic opacity to optical/infrared photons from large dust grains (with radii in the range a=0.2-2.0 mum) to a level tau_GD<0.15(F_halo/10%) to a redshift z~1. Our results are only weakly dependent on the grain size distribution or the redshift evolution of the intergalactic dust. Stacking X-ray images of AGN can be used to improve our constraints and diminish the importance of dust as a source of systematic uncertainty for future supernova surveys which aim to improve the precision on measuring the redshift evolution of the dark energy equation-of-state.

  13. NGC 604, the Scaled OB Association (SOBA) Prototype. I: Spatial Distribution of the Different Gas Phases and Attenuation by Dust

    CERN Document Server

    Maíz-Appelániz, J; Mas-Hesse, J M

    2004-01-01

    We have analyzed HST and ground-based data to characterize the different gas phases and their interaction with the MYC in NGC 604, a GHR in M33. The warm ionized gas is made out of two components: a high-excitation, high-surface brightness H II surface located at the faces of the molecular clouds directly exposed to the ionizing radiation of the central SOBA; and a low-excitation, low-surface brightness halo that extends to much larger distances from the ionizing stars. The cavities created by the winds and SN explosions are filled with X-ray-emitting coronal gas. The nebular lines emitted by the warm gas experience a variable attenuation as a consequence of the dust distribution, which is patchy in the plane of the sky and with clouds interspersed among emission-line sources in the same line of sight. The optical depth at H alpha as measured from the ratio of the thermal radio continuum to H alpha shows a very good correlation with the total CO (1-0) column, indicating that most of the dust resides in the co...

  14. Physical properties, chemical composition, sources, spatial distribution and sinks of indoor aerosol particles in a university lecture hall

    Science.gov (United States)

    Salma, I.; Dosztály, K.; Borsós, T.; Söveges, B.; Weidinger, T.; Kristóf, G.; Péter, N.; Kertész, Zs.

    2013-01-01

    PM10 mass, particle number (N) and CO2 concentrations, particle number size distributions and meteorological parameters were determined with high time resolution, and daily aerosol samples were collected in the PM10-2.0 and PM2.0 size fractions for chemical analysis in the middle of a university lecture hall for one week. Median concentrations for the PM10 mass and N of 15.3 μg m-3 and 3.7 × 103 cm-3, respectively were derived. The data are substantially smaller than the related outdoor levels or typical values for residences. There were considerable concentration differences for workdays, weekends and various lectures. Main sources of PM10 mass include the usage of chalk sticks for writing, wiping the blackboard, ordinary movements and actions of students and cleaning. High PM10 mass concentration levels up to 100 μg m-3 were realised for short time intervals after wiping the blackboard. The mass concentrations decreased rapidly after the emission source ceased to be active. Two classes of coarse particles were identified. General indoor dust particles exhibited a residence time of approximately 35 min, while the residence time for the chalk dust particles was approximately 20 min as lower estimates. Emission source rate for wiping the blackboard was estimated to be between 8 and 14 mg min-1. This represents a substantial emission rate but the source is active only up to 1 min. Suspension of the chalk (made mainly of gypsum) dust particles was confirmed by enrichment of Ca and S in the hall with respect to ambient urban aerosol. Contribution of ambient aerosol via the heating, ventilation and air conditioning (HVAC) facility was considerable for time intervals when the indoor sources of PM10 mass were not intensive. The HVAC facility introduces, however, the major amount of aerosol particles from the outdoors as far as their number concentration is regarded. Mean contribution of ultrafine particles to the total particle number was (69 ± 7)%, which is smaller

  15. Spatial distribution, health risk assessment, and isotopic composition of lead contamination of street dusts in different functional areas of Beijing, China.

    Science.gov (United States)

    Han, Lanfang; Gao, Bo; Wei, Xin; Xu, Dongyu; Gao, Li

    2016-02-01

    Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at "low pollution risk" status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas.

  16. High Angular Resolution Observations of Episodic Dust Emission from Long Period Variable Stars Twenty Years of Observations with the Berkeley Infrared Spatial Interferometer

    Science.gov (United States)

    Danchi, William

    2010-01-01

    Over the past twenty years the U. C. Berkeley Infrared Spatial Interferometer has observed a number of Long Period Variable stars in the mid-infrared, obtaining information on the spatial distribution of dust around these stars with resolutions of the order of a few tens of milliarcseconds. The ISI is a heterodyne interferometer operating mostly at 11.15 microns, initially with two telescopes. In the last decade, it has been taking data regularly with three telescopes, thus obtaining visibility data on three baselines and also a closure phase. Over the course of the years, the ISI has been able to measure the physical properties of the dust shells surrounding these stars, in particular the inner radii of the dust shells, as well as the temperature and density distribution. For some stars, the ISI has also made precision measurements of their diameters in the mid-infrared. Closure phase measurements have revealed asymmetries in the dust distributions around many stars. Most surprisingly the ISI data has shown evidence for substantial changes in the amount of dust on time scales of 5-10 years, rather than being directly correlated with the stellar pulsation periods, which are of the order of one year. We discuss past results and new results from the ISI that highlight the dynamic environment around these stars.

  17. Effects of two Asian sand dusts transported from the dust source regions of Inner Mongolia and northeast China on murine lung eosinophilia

    Energy Technology Data Exchange (ETDEWEB)

    He, Miao, E-mail: hemiao.cmu@gmail.com [Environment and Chronic Non-communicable Disease Research Center, College of Public Health, China Medical University, 11001 Shenyang (China); Department of Health Sciences, Oita University of Nursing and Health Sciences, 870-1201 Oita (Japan); Ichinose, Takamichi, E-mail: ichinose@oita-nhs.ac.jp [Department of Health Sciences, Oita University of Nursing and Health Sciences, 870-1201 Oita (Japan); Song, Yuan, E-mail: freude@med.uoeh-u.ac.jp [Department of Immunology and Parasitology, School of Medicine, University of Occupational and Environmental Health, Iseigaoka, Yahata-nishi-ku, Kitakyushu, 807-8555 Fukuoka (Japan); Yoshida, Yasuhiro, E-mail: songyuan1107@163.com [Department of Immunology and Parasitology, School of Medicine, University of Occupational and Environmental Health, Iseigaoka, Yahata-nishi-ku, Kitakyushu, 807-8555 Fukuoka (Japan); Arashidani, Keiichi, E-mail: arashi@snow.ocn.ne.jp [Department of Immunology and Parasitology, School of Medicine, University of Occupational and Environmental Health, Iseigaoka, Yahata-nishi-ku, Kitakyushu, 807-8555 Fukuoka (Japan); Yoshida, Seiichi, E-mail: syoshida@oita-nhs.ac.jp [Department of Health Sciences, Oita University of Nursing and Health Sciences, 870-1201 Oita (Japan); Liu, Boying, E-mail: boyingliu321@gmail.com [Environment and Chronic Non-communicable Disease Research Center, College of Public Health, China Medical University, 11001 Shenyang (China); Department of Health Sciences, Oita University of Nursing and Health Sciences, 870-1201 Oita (Japan); Nishikawa, Masataka, E-mail: mnishi@nies.go.jp [Environmental Chemistry Division, National Institute for Environmental Studies, 305-8506 Tsukuba, Ibaraki (Japan); Takano, Hirohisa, E-mail: htakano@health.env.kyoto-u.ac.jp [Environmental Health Division, Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto daigaku-Katsura, Nishikyo-ku, Kyoto 615-8530 (Japan); and others

    2013-11-01

    The quality and quantity of toxic materials adsorbed onto Asian sand dust (ASD) are different based on dust source regions and passage routes. The aggravating effects of two ASDs (ASD1 and ASD2) transported from the source regions of Inner Mongolia and northeast China on lung eosinophilia were compared to clarify the role of toxic materials in ASD. The ASDs contained different amounts of lipopolysaccharides (LPS) and β-glucan (ASD1 < ASD2) and SiO{sub 2} (ASD1 > ASD2). CD-1 mice were instilled intratracheally with ASD1, ASD2 and/or ovalbumin (OVA) four times at 2-week intervals. ASD1 and ASD2 enhanced eosinophil recruitment induced by OVA in the submucosa of the airway, with goblet cell proliferation in the bronchial epithelium. ASD1 and ASD2 synergistically increased OVA-induced eosinophil-relevant cytokines interleukin-5 (IL-5), IL-13 (ASD1 < ASD2) and chemokine eotaxin (ASD1 > ASD2) in bronchoalveolar lavage fluid. ASD2 aggravating effects on lung eosinophilia were greater than ASD1. The role of LPS and β-glucan in ASD2 on the production of pro-inflammatory mediators was assessed using in vitro bone marrow-derived macrophages (BMDMs) from wild type, Toll-like receptor 2-deficient (TLR2 −/−), TLR4 −/−, and MyD88 −/− mice (on Balb/c background). ASD2-stimulated TLR2 −/− BMDMs enhanced IL-6, IL-12, TNF-α, MCP-1 and MIP-1α secretion compared with ASD2-stimulated TLR4 −/− BMDMs. Protein expression from ASD2-stimulated MyD88 −/− BMDM were very low or undetectable. The in vitro results indicate that lung eosinophilia caused by ASD is TLR4 dependent. Therefore, the aggravation of OVA-related lung eosinophilia by ASD may be dependent on toxic substances derived from microbes, such as LPS, rather than SiO{sub 2}. - Highlights: • Asian sand dust (ASD) from the deserts of China causes serious respiratory problems. • The aggravating effects of two ASDs on lung eosinophilia were compared. • The ASDs contained different LPS and β-glucan (ASD1

  18. Identification of historical lead sources in roof dusts and recent lake sediments from an industrialized area: indications from lead isotopes.

    Science.gov (United States)

    Chiaradia, M; Chenhall, B E; Depers, A M; Gulson, B L; Jones, B G

    1997-10-20

    X-ray fluorescence and stable lead (Pb) isotopic analyses have been undertaken on dusts, known from microscopic investigation to contain significant quantities of industrially- and urban-derived particulate matter, present in the roof cavities of houses in the Illawarra region (N.S.W., Australia), with the objective of examining the historic record of Pb pollution. All investigated houses contained in excess of 250 micrograms g-1 Pb, with dwellings close to a copper smelter, in a large industrial complex including a major steelworks, containing higher (> 2500 micrograms g-1) Pb concentrations. The isotopic composition in the dusts, expressed here as 206Pb/204Pb, is relatively constant at 17.0, irrespective of dwelling age or distance from the industrial complex. Contamination of the dusts by Pb sourced from paint cannot explain the isotopic uniformity of the dust samples. Isotopic modelling indicates that the dusts contain Pb derived from the copper smelter, gasoline-air Pb and a minor contribution from coal-utilising sources. Lead loading was also investigated in the adjacent lagoon, which acts as a natural sink for particulate matter in the Illawarra region. Isotopic data and modelling indicate that one natural and four anthropogenic sources contribute to the Pb burden of this lagoon. The natural source consists of Permian rocks cropping out in the catchment area which have a 206Pb/204Pb of approximately 18.7. The suggested anthropogenic sources are an old disbanded base-metal (Pb) smelter (206Pb/204Pb approximately 16.2-16.3), the copper smelter (206Pb/204Pb approximately 17.9), gasoline-air derived Pb (206Pb/204Pb approximately 16.4-16.5) and industries utilising coal, for example the recently closed thermal coal-fired power station (206Pb/204Pb approximately 18.9). The relative contributions of the base-metal (mainly lead) smelter and gasoline-air Pb in the sediment can only be partly assessed due to the isotopic similarity of these sources. Likewise the

  19. House-dust mites in our homes are a contamination from outdoor sources

    DEFF Research Database (Denmark)

    Hallas, Thorkil E.

    2010-01-01

    Avoidance advices for house-dust mite sensitized persons are currently based upon the idea, that the mites (Dermatophagoides spp.) are part of the indoor fauna. A closer look at development stages in the house-dust samples shows, however, that only the mites' active stages are present there and t...... no effect of avoidance measures. The verification of the entire hypothesis or part of it may have great impact on the management of the disease house-dust mite allergy.......Avoidance advices for house-dust mite sensitized persons are currently based upon the idea, that the mites (Dermatophagoides spp.) are part of the indoor fauna. A closer look at development stages in the house-dust samples shows, however, that only the mites' active stages are present...... there and that the stages between them, the inactive moulting stages, are absent. Therefore the mites probably do not carry out their life cycles in our dwellings, but are more likely contaminations from the open. Findings of low level concentrations can be explained by mites coming from outdoors and sedimented...

  20. The anthropogenic magnetic particles contain in indoor dust as markers of pollution emitted by different outside sources.

    Science.gov (United States)

    Szczepaniak, Iga; Górka-Kostrubiec, Beata

    2015-04-01

    The aim of the study was to explain the impact of magnetic particles originated from different external sources of pollution on the air quality inside apartments. We used the indoor dust as an indicator of air pollution inside apartments. For the study, a small town was chosen, in which dominated the local sources of pollution: (1) vehicle traffic (in the city center), (2) local heating plant, (3) individual households (in the suburbs) and (4) re-emission of soil particles from the contaminated post-industrial area. In each of four areas were selected several private apartments as a sampling points. Dust samples were collected by the owners of apartments from the floor surface using vacuum cleaners in the same time period (September 2014). The concentration-dependent magnetic parameters (magnetic susceptibility - and magnetization MS) were used to determine the level of the magnetic pollution of the indoor dust. The properties of magnetic particles (mineralogy, domain structure and grain size), and their chemical composition were used to describe and identify the source of air pollution inside the apartments. Generally, the results showed that in each of studied areas were observed flats with both: very high and low values of parameters depending on the concentration of magnetic particles. The biggest differences between the areas were visible in mineralogy of magnetic fraction of pollution. The research of apartments exposed to pollution generated by vehicle traffic (located in the city center) show a wide range of values χ (75-1021 -10-8 m3kg-1) and MS (35-656 -10-3 Am2kg-1). These differences were due to the high contribution of pure iron to magnetic fraction of pollution. Detailed analysis of the M (T) curves revealed two magnetic transitions: first at a temperature Tc = 585oC for magnetite and the second at Tc = 760oC for pure iron. For the dust samples from the city center the high values of χ and MS well correlated with high level of anthropogenic elements

  1. Iron oxide minerals in dust-source sediments from the Bodélé Depression, Chad: Implications for radiative properties and Fe bioavailability of dust plumes from the Sahara

    Science.gov (United States)

    Moskowitz, Bruce M; Reynolds, Richard; Goldstein, Harland; Beroquo, Thelma; Kokaly, Raymond; Bristow, Charlie S

    2016-01-01

    Atmospheric mineral dust can influence climate and biogeochemical cycles. An important component of mineral dust is ferric oxide minerals (hematite and goethite) which have been shown to influence strongly the optical properties of dust plumes and thus affect the radiative forcing of global dust. Here we report on the iron mineralogy of dust-source samples from the Bodélé Depression (Chad, north-central Africa), which is estimated to be Earth’s most prolific dust producer and may be a key contributor to the global radiative budget of the atmosphere as well as to long-range nutrient transport to the Amazon Basin. By using a combination of magnetic property measurements, Mössbauer spectroscopy, reflectance spectroscopy, chemical analysis, and scanning electron microscopy, we document the abundance and relative amounts of goethite, hematite, and magnetite in dust-source samples from the Bodélé Depression. The partition between hematite and goethite is important to know to improve models for the radiative effects of ferric oxide minerals in mineral dust aerosols. The combination of methods shows (1) the dominance of goethite over hematite in the source sediments, (2) the abundance and occurrences of their nanosize components, and (3) the ubiquity of magnetite, albeit in small amounts. Dominant goethite and subordinate hematite together compose about 2% of yellow-reddish dust-source sediments from the Bodélé Depression and contribute strongly to diminution of reflectance in bulk samples. These observations imply that dust plumes from the Bodélé Depression that are derived from goethite-dominated sediments strongly absorb solar radiation. The presence of ubiquitous magnetite (0.002–0.57 wt%) is also noteworthy for its potentially higher solubility relative to ferric oxide and for its small sizes, including PM < 0.1 μm. For all examined samples, the average iron apportionment is estimated at about 33% in ferric oxide minerals, 1.4% in magnetite, and 65

  2. Iron solubility driven by speciation in dust sources to the ocean

    Science.gov (United States)

    Schroth, A.W.; Crusius, J.; Sholkovitz, E.R.; Bostick, B.C.

    2009-01-01

    Although abundant in the Earths crust, iron is present at trace concentrations in sea water and is a limiting nutrient for phytoplankton in approximately 40% of the ocean. Current literature suggests that aerosols are the primary external source of iron to offshore waters, yet controls on iron aerosol solubility remain unclear. Here we demonstrate that iron speciation (oxidation state and bonding environment) drives iron solubility in arid region soils, glacial weathering products (flour) and oil combustion products (oil fly ash). Iron speciation varies by aerosol source, with soils in arid regions dominated by ferric (oxy)hydroxides, glacial flour by primary and secondary ferrous silicates and oil fly ash by ferric sulphate salts. Variation in iron speciation produces systematic differences in iron solubility: less than 1% of the iron in arid soils was soluble, compared with 2-3% in glacial products and 77-81% in oil combustion products, which is directly linked to fractions of more soluble phases. We conclude that spatial and temporal variations in aerosol iron speciation, driven by the distribution of deserts, glaciers and fossil-fuel combustion, could have a pronounced effect on aerosol iron solubility and therefore on biological productivity and the carbon cycle in the ocean. ?? 2009 Macmillan Publishers Limited.

  3. Inhaled dust and disease

    Energy Technology Data Exchange (ETDEWEB)

    Holt, P.F.

    1987-01-01

    This book discusses the following: the respiratory system; respirable dust; the fate of inhaled dust; translocation and some general effects of inhaled dust; silicosis; experimental research on silica-related disease; natural fibrous silicates; asbestos dust levels and dust sources; asbestos-related diseases - asbestosis, lung cancer, mesothelioma and other diseases, cancers at sites other than lung and pleura; experimental research relating to asbestos-related diseases; asbestos hazard - mineral types and hazardous occupations, neighbourhood and domestic hazard; silicates other than asbestos-man-made mineral fibres, mineral silicates and cement; metals; coal mine dust, industrial carbon and arsenic; natural and synthetic organic substances; dusts that provoke allergic alveolitis; tobacco smoke.

  4. Airborne Petcoke Dust is a Major Source of Polycyclic Aromatic Hydrocarbons in the Athabasca Oil Sands Region.

    Science.gov (United States)

    Zhang, Yifeng; Shotyk, William; Zaccone, Claudio; Noernberg, Tommy; Pelletier, Rick; Bicalho, Beatriz; Froese, Duane G; Davies, Lauren; Martin, Jonathan W

    2016-02-16

    Oil sands mining has been linked to increasing atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in the Athabasca oil sands region (AOSR), but known sources cannot explain the quantity of PAHs in environmental samples. PAHs were measured in living Sphagnum moss (24 sites, n = 68), in sectioned peat cores (4 sites, n = 161), and snow (7 sites, n = 19) from ombrotrophic bogs in the AOSR. Prospective source samples were also analyzed, including petroleum coke (petcoke, from both delayed and fluid coking), fine tailings, oil sands ore, and naturally exposed bitumen. Average PAH concentrations in near-field moss (199 ng/g, n = 11) were significantly higher (p = 0.035) than in far-field moss (118 ng/g, n = 13), and increasing temporal trends were detected in three peat cores collected closest to industrial activity. A chemical mass-balance model estimated that delayed petcoke was the major source of PAHs to living moss, and among three peat core the contribution to PAHs from delayed petcoke increased over time, accounting for 45-95% of PAHs in contemporary layers. Petcoke was also estimated to be a major source of vanadium, nickel, and molybdenum. Scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed large petcoke particles (>10 μm) in snow at near-field sites. Petcoke dust has not previously been considered in environmental impact assessments of oil sands upgrading, and improved dust control from growing stockpiles may mitigate future risks.

  5. Quantifying the anthropogenic dust emission from agricultural land use and desiccation of the Aral Sea in Central Asia

    Science.gov (United States)

    Xi, Xin; Sokolik, Irina N.

    2016-10-01

    A regional dust model system is applied to quantify the anthropogenic dust emission in the post-Soviet Central Asia from 2000 to 2014. Two physically based dust schemes suggest that a proportion of 18.3-32.8% of total dust emissions is contributed by agricultural land use and the desiccation of Aral Sea, whereas a simplified dust scheme yields higher estimates in the range of 49.7-56.5% depending on whether a static or dynamic preferential dust source function is used. The dust schemes also differ greatly in the spatial distribution of anthropogenic dust and the sensitivity to the use of land use intensity in separating natural and human-made source areas, suggesting that the model representation of erosion threshold velocity, especially the role of vegetation, is a key source of model uncertainty in quantifying anthropogenic dust. The relative importance of agriculture and dried Aral Sea bed (Aralkum) differs greatly among the dust schemes. Despite the increased dust from the expansion of Aralkum, there is a negative trend in the anthropogenic dust proportion, indicating a shift of dust emission toward natural source areas. All dust schemes show a decrease in anthropogenic dust in response to land cover changes over agricultural lands.

  6. Coal-tar-based parking lot sealcoat: An unrecognized source of PAH to settled house dust

    Science.gov (United States)

    Mahler, B.J.; Van Metre, P.C.; Wilson, J.T.; Musgrove, M.; Burbank, T.L.; Ennis, T.E.; Bashara, T.J.

    2010-01-01

    Despite much speculation, the principal factors controlling concentrations of polycyclic aromatic hydrocarbons (PAH) in settled house dust (SHD) have not yet been identified. In response to recent reports that dust from pavement with coaltar-based sealcoat contains extremely high concentrations of PAH, we measured PAH in SHD from 23 apartments and in dust from their associated parking lots, one-half of which had coal-tar-based sealcoat (CT). The median concentration of total PAH (T-PAH) in dust from CT parking lots (4760 ??g/g, n = 11) was 530 times higher than that from parking lots with other pavement surface types (asphalt-based sealcoat, unsealed asphalt, concrete [median 9.0 ??g/g, n = 12]). T-PAH in SHD from apartments with CT parking lots (median 129 ??g/g) was 25 times higher than that in SHD from apartments with parking lots with other pavement surface types (median 5.1 ??g/g). Presence or absence of CT on a parking lot explained 48% of the variance in log-transformed T-PAH in SHD. Urban land-use intensity near the residence also had a significant but weaker relation to T-PAH. No other variables tested, including carpeting, frequency of vacuuming, and indoor burning, were significant. ?? 2010 American Chemical Society.

  7. Materials as inherent ignition sources for dust explosions during spray drying

    NARCIS (Netherlands)

    Hoogenband, V. van den; Maaijer, M. de; Versloot, N.H.A.

    2010-01-01

    During spray drying where a solution is dispersed in small droplets through a nozzle the liquid evaporates by means of hot air. In a large number of these processes organic materials are processed so three out of four factors for dust explosions to occur are already present. The only thing missing f

  8. Coal-tar-based parking lot sealcoat: an unrecognized source of PAH to settled house dust.

    Science.gov (United States)

    Mahler, Barbara J; Metre, Peter C Van; Wilson, Jennifer T; Musgrove, Marylynn; Burbank, Teresa L; Ennis, Thomas E; Bashara, Thomas J

    2010-02-01

    Despite much speculation, the principal factors controlling concentrations of polycyclic aromatic hydrocarbons (PAH) in settled house dust (SHD) have not yet been identified. In response to recent reports that dust from pavement with coal-tar-based sealcoat contains extremely high concentrations of PAH, we measured PAH in SHD from 23 apartments and in dust from their associated parking lots, one-half of which had coal-tar-based sealcoat (CT). The median concentration of total PAH (T-PAH) in dust from CT parking lots (4760 microg/g, n = 11) was 530 times higher than that from parking lots with other pavement surface types (asphalt-based sealcoat, unsealed asphalt, concrete [median 9.0 microg/g, n = 12]). T-PAH in SHD from apartments with CT parking lots (median 129 microg/g) was 25 times higher than that in SHD from apartments with parking lots with other pavement surface types (median 5.1 microg/g). Presence or absence of CT on a parking lot explained 48% of the variance in log-transformed T-PAH in SHD. Urban land-use intensity near the residence also had a significant but weaker relation to T-PAH. No other variables tested, including carpeting, frequency of vacuuming, and indoor burning, were significant.

  9. Atmospheric aerosols in Rome, Italy: sources, dynamics and spatial variations during two seasons

    Science.gov (United States)

    Struckmeier, Caroline; Drewnick, Frank; Fachinger, Friederike; Gobbi, Gian Paolo; Borrmann, Stephan

    2016-12-01

    Investigations on atmospheric aerosols and their sources were carried out in October/November 2013 and May/June 2014 consecutively in a suburban area of Rome (Tor Vergata) and in central Rome (near St Peter's Basilica). During both years a Saharan dust advection event temporarily increased PM10 concentrations at ground level by about 12-17 µg m-3. Generally, in October/November the ambient aerosol was more strongly influenced by primary emissions, whereas higher relative contributions of secondary particles (sulfate, aged organic aerosol) were found in May/June. Absolute concentrations of anthropogenic emission tracers (e.g. NOx, CO2, particulate polycyclic aromatic hydrocarbons, traffic-related organic aerosol) were generally higher at the urban location. Positive matrix factorization was applied to the PM1 organic aerosol (OA) fraction of aerosol mass spectrometer (HR-ToF-AMS) data to identify different sources of primary OA (POA): traffic, cooking, biomass burning and (local) cigarette smoking. While biomass burning OA was only found at the suburban site, where it accounted for the major fraction of POA (18-24 % of total OA), traffic and cooking were more dominant sources at the urban site. A particle type associated with cigarette smoke emissions, which is associated with a potential characteristic marker peak (m/z 84, C5H10N+, a nicotine fragment) in the mass spectrum, was only found in central Rome, where it was emitted in close vicinity to the measurement location. Regarding secondary OA, in October/November, only a very aged, regionally advected oxygenated OA was found, which contributed 42-53 % to the total OA. In May/June total oxygenated OA accounted for 56-76 % of the OA. Here a fraction (18-26 % of total OA) of a fresher, less oxygenated OA of more local origin was also observed. New particle formation events were identified from measured particle number concentrations and size distributions in May/June 2014 at both sites. While they were observed

  10. Product screening for sources of halogenated flame retardants in Canadian house and office dust

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Golnoush [Department of Geography, University of Toronto, 100 St. George St., Toronto M5S 3G3 (Canada); Saini, Amandeep [Department of Physical and Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto M1C 1A4 (Canada); Goosey, Emma [Department of Earth Sciences, University of Toronto, 22 Russell Street, Toronto M5S 3B1 (Canada); Diamond, Miriam L., E-mail: miriam.diamond@utoronto.ca [Department of Earth Sciences, University of Toronto, 22 Russell Street, Toronto M5S 3B1 (Canada); Department of Physical and Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto M1C 1A4 (Canada)

    2016-03-01

    Human exposure to halogenated flame retardants (HFRs) such as polybrominated diphenyl ethers (PBDEs) and their replacements, can be related to exposure to indoor dust and direct contact with HFR-containing products. This study aimed to identify electronic products that contributed to HFRs measured in indoor dust and to develop a screening method for identifying HFRs in hard polymer products. Concentrations of 10 PBDEs and 12 halogenated replacements in dust and surface wipe samples of hard polymer casings of electronic products plus Br in the surfaces of those casing measured using X-ray fluorescence (XRF) were analyzed from 35 homes and 10 offices in Toronto (ON, Canada). HFR concentrations in dust and product wipes were positively correlated. Thus, we hypothesize that electronic products with the highest HFR concentrations contribute the most to concentrations in dust, regardless of the volatility of the HFR. Abundant HFRs in dust and product wipes were PBDEs (BDE-47, 99, 100, 153, 154, 183, 209), TDCPP, DBDPE, EH-TBB and BEHTBP. Older CRT TVs had the highest concentration of BDE-209 of all products tested. This was followed by higher concentrations of HFRs in PCs, Audio/Video (A/V) devices, small household appliances (HHAs) and flat screen TVs. The removal of HFRs from polymer surfaces using wipes supports concerns that HFRs could be transferred from these surfaces to hands as a result of direct contact with HFR-containing products. Surface wipe testing shows promise for screening additive HFRs. In comparison, the Br-content obtained using a handheld XRF analyzer did not correspond to concentrations obtained from surface wipe testing. - Highlights: • Concentrations of flame retardants in dust correlated with product surface wipes • Most abundant FRs in electronics were PBDEs, TDCPP, DBDPE, EH-TBB and BEHTBP. • Descending order of FRs in CRTs, TVs, PCs, A-V devices, and small household appliances • Product wipe testing, but not XRF, useful for non

  11. Spatial Correlation Between Dust and H$\\alpha$ Emission in Dwarf Irregular Galaxies

    CERN Document Server

    Jimmy,; Saintonge, Amélie; Accurso, Gioacchino; Brough, Sarah; Oliva-Altamirano, Paola; Salmon, Brett; Forrest, Ben

    2016-01-01

    Using a sample of dwarf irregular galaxies selected from the ALFALFA blind HI-survey and observed using the VIMOS IFU, we investigate the relationship between H$\\alpha$ emission and Balmer optical depth ($\\tau_{\\text{b}}$). We find a positive correlation between H$\\alpha$ luminosity surface density and Balmer optical depth in 8 of 11 at $\\geq$ 0.8$\\sigma$ significance (6 of 11 at $\\geq$ 1.0$\\sigma$) galaxies. Our spaxels have physical scales ranging from 30 to 80 pc, demonstrating that the correlation between these two variables continues to hold down to spatial scales as low as 30 pc. Using the Spearman's rank correlation coefficient to test for correlation between $\\Sigma_{\\text{H}\\alpha}$ and $\\tau_{\\text{b}}$ in all the galaxies combined, we find $\\rho = 0.39$, indicating a positive correlation at 4$\\sigma$ significance. Our low stellar-mass galaxy results are in agreement with observations of emission line regions in larger spiral galaxies, indicating that this relationship is independent of the size of ...

  12. Dust storm events over Delhi: verification of dust AOD forecasts with satellite and surface observations

    Science.gov (United States)

    Singh, Aditi; Iyengar, Gopal R.; George, John P.

    2016-05-01

    Thar desert located in northwest part of India is considered as one of the major dust source. Dust storms originate in Thar desert during pre-monsoon season, affects large part of Indo-Gangetic plains. High dust loading causes the deterioration of the ambient air quality and degradation in visibility. Present study focuses on the identification of dust events and verification of the forecast of dust events over Delhi and western part of IG Plains, during the pre-monsoon season of 2015. Three dust events have been identified over Delhi during the study period. For all the selected days, Terra-MODIS AOD at 550 nm are found close to 1.0, while AURA-OMI AI shows high values. Dust AOD forecasts from NCMRWF Unified Model (NCUM) for the three selected dust events are verified against satellite (MODIS) and ground based observations (AERONET). Comparison of observed AODs at 550 nm from MODIS with NCUM predicted AODs reveals that NCUM is able to predict the spatial and temporal distribution of dust AOD, in these cases. Good correlation (~0.67) is obtained between the NCUM predicted dust AODs and location specific observations available from AERONET. Model under-predicted the AODs as compared to the AERONET observations. This may be mainly because the model account for only dust and no anthropogenic activities are considered. The results of the present study emphasize the requirement of more realistic representation of local dust emission in the model both of natural and anthropogenic origin, to improve the forecast of dust from NCUM during the dust events.

  13. Simulation of source intensity variations from atmospheric dust for solar occultation Fourier transform infrared spectroscopy at Mars

    Science.gov (United States)

    Olsen, K. S.; Toon, G. C.; Strong, K.

    2016-05-01

    A Fourier transform spectrometer observing in solar occultation mode from orbit is ideally suited to detecting and characterizing vertical profiles of trace gases in the Martian atmosphere. This technique benefits from a long optical path length and high signal strength, and can have high spectral resolution. The Martian atmosphere is often subject to large quantities of suspended dust, which attenuates solar radiation along the line-of-sight. An instrument making solar occultation measurements scans the limb of the atmosphere continuously, and the optical path moves through layers of increasing or decreasing dust levels during a single interferogram acquisition, resulting in time-varying signal intensity. If uncorrected, source intensity variations (SIVs) can affect the relative depth of absorption lines, negatively impacting trace gas retrievals. We have simulated SIVs using synthetic spectra for the Martian atmosphere, and investigated different techniques to mitigate the effects of SIVs. We examined high-pass filters in the wavenumber domain, and smoothing methods in the optical path difference (OPD) domain, and conclude that using a convolution operator in the OPD domain can isolate the SIVs and be used to correct for it. We observe spectral residuals of less than 0.25% in both high- and low-dust conditions, and retrieved volume mixing ratio vertical profile differences on the order of 0.5-3% for several trace gases known to be present in the Martian atmosphere. These differences are smaller than those caused by adding realistic noise to the spectra. This work thus demonstrates that it should be possible to retrieve vertical profiles of trace gases in a dusty Martian atmosphere using solar occultation if the interferograms are corrected for the effects of dust.

  14. Contributions To The Study Of Heavy Metals Concentration Variation In Sedimentable Dusts According To The Distance From The Pollution Source

    Directory of Open Access Journals (Sweden)

    Mariana DOBRA

    2006-01-01

    Full Text Available The environment in areas where geological and mining activities, such as the extraction of ores containing heavy metals, take place, is heavily polluted with dusts resulting from these activities, as well as with residual waters from the mines. Depending on the meteorological conditions, as well as on the conditions under which sedimentable dusts or dusts in suspension are emitted into the air, the distance from the main pollution source varies considerably. In order to estimate the pollution level and the danger presented by this phenomenon, some analyses are required with regard to determining the concentration of heavy pollutant metals in air, soil and plants samples, as well as in dusts from the air. For the precise determination of the major components, as well as the minor ones, and also the ones in traces, the analytical techniques used must have low detection limits and the lowest matrix effects possible [1,2]. The methods that respond to these requirements are from the category of inductively coupled plasma atomic emission spectrometry (ICP-AES. The research was done in an area where there are industrial units whose main field of activity is extraction of certain ores which contain Pb, Cu and Zn as major components, as well as Cr, Mn, Ni, Co, Ag, Au, Al, and Fe as minor components or in traces. It is obvious that the presence of these metals in the air, water and soil has a negative impact on human health, plants and animals. This paper is a study of these aspects in an area where pollution with heavy metals reaches alarming quotas.

  15. Temporal and Spatial Distribution of Respirable Dust After Blasting of Coal Roadway Driving Faces: A Case Study

    Directory of Open Access Journals (Sweden)

    Shengyong Hu

    2015-10-01

    Full Text Available Coal roadway driving is an important part of the underground mining system, and very common in Chinese coal mines. However, the high concentration of respirable dust produced in the blasting operation poses a great hazard to miners’ health as well as the underground environment. In this paper, based on the direct simulation Monte Carlo method, the gas–solid two-phase flow model of particle movement is established to study the respirable dust distribution in blasting driving face. The results show that there is an obvious vortex region in which airflow velocity is lower than that close to the roadway wall and driving face. After blasting, respirable dust in the front of the dust group jet from the driving face cannot be discharged timely, with the result that its concentration is higher than the critical value until it is expelled from the roadway, whereas respirable dust concentration at the back of the dust group is gradually diluted and exhibits an alternate thin dense phase distribution. Meanwhile, respirable dust concentration in the breathing zone is relatively higher than that at the top and bottom of roadway. The accuracy of numerical simulation results is verified by field measurements. The research results are helpful for further understanding the evolution of respirable dust distribution after blasting, and are good for providing guidance for efficient controlling of respirable dust and improving the working environment for underground miners.

  16. PM10 concentration levels at an urban and background site in Cyprus: the impact of urban sources and dust storms.

    Science.gov (United States)

    Achilleos, Souzana; Evans, John S; Yiallouros, Panayiotis K; Kleanthous, Savvas; Schwartz, Joel; Koutrakis, Petros

    2014-12-01

    Air quality in Cyprus is influenced by both local and transported pollution, including desert dust storms. We examined PM10 concentration data collected in Nicosia (urban representative) from April 1, 1993, through December 11, 2008, and in Ayia Marina (rural background representative) from January 1, 1999, through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM10 concentrations, meteorological records, and satellite data were used to identify dust storm days. We investigated long-term trends using a Generalized Additive Model (GAM) after controlling for day of week, month, temperature, wind speed, and relative humidity. In Nicosia, annual PM10 concentrations ranged from 50.4 to 63.8 μg/m3 and exceeded the EU annual standard limit enacted in 2005 of 40 μg/m3 every year A large, statistically significant impact of urban sources (defined as the difference between urban and background levels) was seen in Nicosia over the period 2000-2008, and was highest during traffic hours, weekdays, cold months, and low wind conditions. Our estimate of the mean (standard error) contribution of urban sources to the daily ambient PM10 was 24.0 (0.4) μg/m3. The study of yearly trends showed that PM10 levels in Nicosia decreased from 59.4 μg/m3 in 1993 to 49.0 μg/m3 in 2008, probably in part as a result of traffic emission control policies in Cyprus. In Ayia Marina, annual concentrations ranged from 27.3 to 35.6 μg/m3, and no obvious time trends were observed. The levels measured at the Cyprus background site are comparable to background concentrations reported in other Eastern Mediterranean countries. Average daily PM10 concentrations during desert dust storms were around 100 μg/m3 since 2000 and much higher in earlier years. Despite the large impact ofdust storms and their increasing frequency over time, dust storms were responsible for a small fraction of the exceedances of the daily PM10 limit. Implications: This

  17. Oxygen isotope signatures of quartz from major Asian dust sources: Implications for changes in the provenance of Chinese loess

    Science.gov (United States)

    Yan, Yan; Sun, Youbin; Chen, Hongyun; Ma, Long

    2014-08-01

    We present a systematic investigation of the oxygen isotopic composition of quartz in both fine and coarse fractions (values of both the fine and coarse fractions from the various sources are overlapped to varying degrees, thus making it difficult to differentiate them. Nevertheless, the quartz δ18O values of both fractions exhibit an increasing trend from the Mongolian Gobi, to the northern Chinese deserts, and then to the Taklimakan desert. This implies that the geological settings of the source areas are different, which in turn results in differing contributions of high-temperature igneous rocks. The combination of quartz δ18O results with other quartz-based provenance tracers can clearly differentiate the three major source areas, i.e., the Taklimakan desert, the Mongolian Gobi, and the northern Chinese deserts. In addition, comparison of our results with previous δ18O measurements of fine-grained quartz from the Luochuan loess sequence suggests the likely glacial-interglacial fluctuations in dust provenance. Finally, we suggest that the combination of quartz δ18O signatures and other dust provenance tracers can potentially improve the recognition of long-term fluctuations in the provenance of Chinese loess-red clay deposits.

  18. The compositions, sources, and size distribution of the dust storm from China in spring of 2000 and its impact on the global environment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The average mass concentration of the aerosols in Beijing during the dust storm in the spring of 2000 was ~6000 mg·m-3, ~30 times as high as that in the non-dust storm days. The enrichment factors of the pollution elements As, Sb and Se were higher than those in the non-dust storm days. This indicated that As, Sb and Se resulted from the pollution sources of those areas, through which the dust storm passed during their long-range transport, in addition to the local pollution sources in Beijing. The enrichment factors of the Pb, Zn, Cd and Cu were much less than those in the non-dust storm days, suggesting that the local pollution sources in Beijing area contributed to them mostly. The enrichment factors of elements Al, Fe, Sc, Mn, Na, Ni, Cr, V and Co were close to 1, showing that these elements originated from crust. The concentration of S in the dust storm was ~10 mg·m-3, 4 times as high as that in non-dust storm. S in the aerosols resulted from the adsorption of gaseous SO2 and the conse-quent transformation on it. The aerosols of the dust storm contained 16.1% and 76.9% of fine particles with the sizes less than 2.1 and 9.0 mm, respectively, while it had a large number of coarse particles. It was noted that a considerable portion of Fe(Ⅱ) was detected from the dust storm. Fe(Ⅱ) could easily dissolve in seawater to be nutrient for phyto-plankton and would lead to the increase of the emission of dimethylsulfide (DMS) from the ocean. The feedbacks of Fe coupled with S in atmosphere might be the important mechanism that would affect the primary productivity in Pacific and/or the global climate change.

  19. The geologic records of dust in the Quaternary

    Science.gov (United States)

    Muhs, Daniel R.

    2013-06-01

    Study of geologic records of dust composition, sources and deposition rates is important for understanding the role of dust in the overall planetary radiation balance, fertilization of organisms in the world's oceans, nutrient additions to the terrestrial biosphere and soils, and for paleoclimatic reconstructions. Both glacial and non-glacial processes produce fine-grained particles that can be transported by the wind. Geologic records of dust flux occur in a number of depositional archives for sediments: (1) loess deposits; (2) lake sediments; (3) soils; (4) deep-ocean basins; and (5) ice sheets and smaller glaciers. These archives have several characteristics that make them highly suitable for understanding the dynamics of dust entrainment, transport, and deposition. First, they are often distributed over wide geographic areas, which permits reconstruction of spatial variation of dust flux. Second, a number of dating methods can be applied to sediment archives, which allows identification of specific periods of greater or lesser dust flux. Third, aeolian sediment particle size and composition can be determined so that dust source areas can be ascertained and dust transport pathways can be reconstructed. Over much of the Earth's surface, dust deposition rates were greater during the last glacial period than during the present interglacial period. A dustier Earth during glacial periods is likely due to increased source areas, greater aridity, less vegetation, lower soil moisture, possibly stronger winds, a decreased intensity of the hydrologic cycle, and greater production of dust-sized particles from expanded ice sheets and glaciers.

  20. Development of PM2.5 source impact spatial fields using a hybrid source apportionment air quality model

    Directory of Open Access Journals (Sweden)

    C. E. Ivey

    2015-01-01

    Full Text Available An integral part of air quality management is knowledge of the impact of pollutant sources on ambient concentrations of particulate matter (PM. There is also a growing desire to directly use source impact estimates in health studies; however, source impacts cannot be directly measured. Several limitations are inherent in most source apportionment methods, which has led to the development of a novel hybrid approach that is used to estimate source impacts by combining the capabilities of receptor modeling (RM and chemical transport modeling (CTM. The hybrid CTM-RM method calculates adjustment factors to refine the CTM-estimated impact of sources at monitoring sites using pollutant species observations and the results of CTM sensitivity analyses, though it does not directly generate spatial source impact fields. The CTM used here is the Community Multi-Scale Air Quality (CMAQ model, and the RM approach is based on the Chemical Mass Balance model. This work presents a method that utilizes kriging to spatially interpolate source-specific impact adjustment factors to generate revised CTM source impact fields from the CTM-RM method results, and is applied to January 2004 over the continental United States. The kriging step is evaluated using data withholding and by comparing results to data from alternative networks. Directly applied and spatially interpolated hybrid adjustment factors at withheld monitors had a correlation coefficient of 0.89, a linear regression slope of 0.83 ± 0.02, and an intercept of 0.14 ± 0.02. Refined source contributions reflect current knowledge of PM emissions (e.g., significant differences in biomass burning impact fields. Concentrations of 19 species and total PM2.5 mass were reconstructed for withheld monitors using directly applied and spatially interpolated hybrid adjustment factors. The mean concentrations of total PM2.5 for withheld monitors were 11.7 (± 8.3, 16.3 (± 11, 8.59 (± 4.7, and 9.20 (± 5.7 μg m−3

  1. Dust in the disk winds from young stars as a source of the circumstellar extinction

    CERN Document Server

    Tambovtseva, L V

    2008-01-01

    We examine a problem of the dust grains survival in the disk wind in T Tauri stars (TTSs). For consideration we choose the disk wind model described by Garcia et al. (2001), where a gas component of the wind is heated by an ambipolar diffusion up to the temperature of the order of 10$^4$ K. It is shown that the dust grains heating due to collisions with the gas atoms and electrons is inefficient in comparison with heating by the stellar radiation, and thus, dust survives even in the hot wind component. Owing to this, the disk wind may be opaque for the ultraviolet and optical radiation of the star and is capable to absorb its noticeable fraction. Calculations show that at the accretion rate $\\dot{M_a} = 10^{-8}-10^{-6} M_\\odot$ per year this fraction for TTSs may range from 20% to 40% of a total luminosity of the star correspondingly. This means that the disk wind in TTSs can play the same role as the puffed inner rim considered in the modern models of accretion disks. In Herbig Ae stars (HAEs) inner regions ...

  2. Multi-Sensor Triangulation of Multi-Source Spatial Data

    Science.gov (United States)

    Habib, Ayman; Kim, Chang-Jae; Bang, Ki-In

    2007-01-01

    The introduced methodologies are successful in: a) Ising LIDAR features for photogrammetric geo-refererncing; b) Delivering a geo-referenced imagery of the same quality as point-based geo-referencing procedures; c) Taking advantage of the synergistic characteristics of spatial data acquisition systems. The triangulation output can be used for the generation of 3-D perspective views.

  3. Second-order spatial correlation in the far-field: Comparing entangled and classical light sources

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Erfeng, E-mail: efzhang@163.com; Liu, Weitao; Lin, Huizu; Chen, Pingxing

    2016-02-15

    Highlights: • Second-order spatial correlation with entangled and classical light in the far-field is investigated. • The role of photon statistics and detection mode in the second-order spatial correlation are discussed. • The difference of second-order spatial correlation with entangled and classical light sources is deduced. - Abstract: We consider second-order spatial correlation with entangled and classical light in the far-field. The quantum theory of second-order spatial correlation is analyzed, and the role of photon statistics and detection mode in the second-order spatial correlation are discussed. Meanwhile, the difference of second-order spatial correlation with entangled and classical light sources is deduced.

  4. Ice nucleation of natural desert dust including organics sourced from nine deserts worldwide

    Science.gov (United States)

    Boose, Yvonne; Welti, André; Atkinson, James; Danielczok, Anja; Bingemer, Heinz; Plötze, Michael; Lohmann, Ulrike; Kanji, Zamin A.

    2017-04-01

    The extraordinary high ice nucleation (IN) potential of microcline, a K-feldspar mineral, at temperatures (T) above 248 and up to 271 K has been show recently. However, it is unclear if microcline is also found at the surface of airborne mineral dust particles or if chemical and mechanical aging processes lead to its destruction or shielding and thus reduced IN ability in the atmosphere. It is suggested that instead organic material mixed with inorganic minerals is responsible for cloud glaciation at T ≥ 253 K. We collected airborne Saharan dust at 4 locations at different distances from the desert and 11 samples from the surface of 9 of the major deserts worldwide. We studied immersion IN on these samples between 235 - 263 K using the IMCA-ZINC (immersion mode cooling chamber - Zurich ice nucleation chamber) setup and the FRIDGE (Franfurt Ice Nuclei Deposition Freezing Experiment) instrument run in droplet freezing mode. By correlating the results with the bulk mineralogy of the dust samples, determined by X-ray diffraction analysis, we show that at 253 K, K-feldspar indeed predicts best the IN behavior of the samples. At lower T (238 - 245 K) however, quartz and the total feldspar contents correlate best. Furthermore, microcline is only found in one of the airborne Saharan dust samples (3.9 wt%) while in the others the amount is below the detection limit or completely absent. Relative humidity (RH) scans at constant T = 238, 240 and 242 K were additionally performed with the portable ice nucleation counter, PINC. Above and below water saturation a similar prominent role of quartz is found as in the immersion mode. To investigate the role of organic material on the IN ability, we heated some of the samples at 573 K for 10 h and repeated the RH-scans. Furthermore, we performed thermogravimetric analysis of the dusts. The two tested airborne Saharan samples loose between 2.8 and 7.5 % of their mass at T ≤ 573 K, partly due to water release, partly due to

  5. Goal-Source Asymmetry and Russian Spatial Prefixes

    Directory of Open Access Journals (Sweden)

    Evgenia Markovskaya

    2007-01-01

    Full Text Available In this paper, I draw on data from Russian to argue for the asymmetry between Goal and Source prepositional phrases. Source prepositional phrases are structurally ambiguous; they can occur both as arguments and adjuncts in certain syntactic contexts. Goal prepositional phrases are unambiguously arguments. I claim that Source prepositions have lexically specified semantics, which determines their relative structural freedom; whereas Goal prepositions are derived from locative prepositions when the building of the event structure takes place and therefore they are bound to be the arguments of the verb.

  6. Delivery of Forecasted Atmospheric Ozone and Dust for the New Mexico Environmental Public Health Tracking System - An Open Source Geospatial Solution

    Science.gov (United States)

    Hudspeth, W. B.; Sanchez-Silva, R.; Cavner, J. A.

    2010-12-01

    New Mexico's Environmental Public Health Tracking System (EPHTS), funded by the Centers for Disease Control (CDC) Environmental Public Health Tracking Network (EPHTN), aims to improve health awareness and services by linking health effects data with levels and frequency of environmental exposure. As a public health decision-support system, EPHTS systems include: state-of-the-art statistical analysis tools; geospatial visualization tools; data discovery, extraction, and delivery tools; and environmental/public health linkage information. As part of its mandate, EPHTS issues public health advisories and forecasts of environmental conditions that have consequences for human health. Through a NASA-funded partnership between the University of New Mexico and the University of Arizona, NASA Earth Science results are fused into two existing models (the Dust Regional Atmospheric Model (DREAM) and the Community Multiscale Air Quality (CMAQ) model) in order to improve forecasts of atmospheric dust, ozone, and aerosols. The results and products derived from the outputs of these models are made available to an Open Source mapping component of the New Mexico EPHTS. In particular, these products are integrated into a Django content management system using GeoDjango, GeoAlchemy, and other OGC-compliant geospatial libraries written in the Python and C++ programming languages. Capabilities of the resultant mapping system include indicator-based thematic mapping, data delivery, and analytical capabilities. DREAM and CMAQ outputs can be inspected, via REST calls, through temporal and spatial subsetting of the atmospheric concentration data across analytical units employed by the public health community. This paper describes details of the architecture and integration of NASA Earth Science into the EPHTS decision-support system.

  7. The brightness and spatial distributions of terrestrial radio sources

    CERN Document Server

    Offringa, A R; Zaroubi, S; Koopmans, L V E; Wijnholds, S J; Abdalla, F B; Brouw, W N; Ciardi, B; Iliev, I T; Harker, G J A; Mellema, G; Bernardi, G; Zarka, P; Ghosh, A; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Beck, R; Bell, M E; Bell, M R; Bentum, M J; Best, P; Bîrzan, L; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; de Gasperin, F; de Geus, E; de Vos, M; Duscha, S; Eislöffel, J; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Grießmeier, J; Hassall, T E; Horneffer, A; Iacobelli, M; Juette, E; Karastergiou, A; Klijn, W; Kondratiev, V I; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Loose, M; Maat, P; Macario, G; Mann, G; McKean, J P; Meulman, H; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Rafferty, D; Reich, W; van Nieuwpoort, R; Röttgering, H; Scaife, A M M; Sluman, J; Smirnov, O; Sobey, C; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Toribio, C; Vermeulen, R; Vocks, C; van Weeren, R J; Wise, M W; Wucknitz, O

    2013-01-01

    Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obstruct the detection of the weak astronomical signals of interest. This issue is especially important for Epoch of Reionisation (EoR) projects that try to detect the faint redshifted HI signals from the time of the earliest structures in the Universe. We explore the RFI situation at 30-163 MHz by studying brightness histograms of visibility data observed with LOFAR, similar to radio-source-count analyses that are used in cosmology. An empirical RFI distribution model is derived that allows the simulation of RFI in radio observations. The brightness histograms show an RFI distribution that follows a power-law distribution with an estimated exponent around -1.5. With several assumptions, this can be explained with a uniform distribution of terrestrial radio sources whose radiation follows existing propagation models. Extrapolation of t...

  8. Maritime Laser Scanning as the Source for Spatial Data

    Directory of Open Access Journals (Sweden)

    Szulwic Jakub

    2015-12-01

    Full Text Available The rapid development of scanning technology, especially mobile scanning, gives the possibility to collect spatial data coming from maritime measurement platforms and autonomous manned or unmanned vehicles. Presented solution is derived from the mobile scanning. However we should keep in mind that the specificity of laser scanning at sea and processing collected data should be in the form acceptable in Geographical Information Systems, especially typical for the maritime needs. At the same time we should be aware that data coming from maritime mobile scanning constitutes a new approach to the describing of maritime environment and brings a new perspective that is completely different than air and terrestrial scanning.

  9. A Noachian source region for the "Black Beauty" meteorite, and a source lithology for Mars surface hydrated dust?

    Science.gov (United States)

    Beck, P.; Pommerol, A.; Zanda, B.; Remusat, L.; Lorand, J. P.; Göpel, C.; Hewins, R.; Pont, S.; Lewin, E.; Quirico, E.; Schmitt, B.; Montes-Hernandez, G.; Garenne, A.; Bonal, L.; Proux, O.; Hazemann, J. L.; Chevrier, V. F.

    2015-10-01

    The Martian surface is covered by a fine-layer of oxidized dust responsible for its red color in the visible spectral range (Bibring et al., 2006; Morris et al., 2006). In the near infrared, the strongest spectral feature is located between 2.6 and 3.6 μm and is ubiquitously observed on the planet (Jouglet et al., 2007; Milliken et al., 2007). Although this absorption has been studied for many decades, its exact attribution and its geological and climatic implications remain debated. We present new lines of evidence from laboratory experiments, orbital and landed missions data, and characterization of the unique Martian meteorite NWA 7533, all converging toward the prominent role of hydroxylated ferric minerals. Martian breccias (so-called "Black Beauty" meteorite NWA7034 and its paired stones NWA7533 and NWA 7455) are unique pieces of the Martian surface that display abundant evidence of aqueous alteration that occurred on their parent planet (Agee et al., 2013). These dark stones are also unique in the fact that they arose from a near surface level in the Noachian southern hemisphere (Humayun et al., 2013). We used IR spectroscopy, Fe-XANES and petrography to identify the mineral hosts of hydrogen in NWA 7533 and compare them with observations of the Martian surface and results of laboratory experiments. The spectrum of NWA 7533 does not show mafic mineral absorptions, making its definite identification difficult through NIR remote sensing mapping. However, its spectra are virtually consistent with a large fraction of the Martian highlands. Abundant NWA 7034/7533 (and paired samples) lithologies might abound on Mars and might play a role in the dust production mechanism.

  10. Spatial and temporal dynamics of methane emissions from agricultural sources in China

    NARCIS (Netherlands)

    Verburg, P.H.; Denier van der Gon, H.A.C.

    2001-01-01

    Agricultural activities contribute significantly to the global methane budget. Agricultural sources of methane are influenced by land-use change, including changes in agricultural area, livestock keeping and agricultural management practices. A spatially explicit inventory of methane emissions from

  11. Spatial and Semantic Validation of Secondary Food Source Data

    OpenAIRE

    Anders K. Lyseen; Henning Sten Hansen

    2014-01-01

    Governmental and commercial lists of food retailers are often used to measure food environments and foodscapes for health and nutritional research. Information about the validity of such secondary food source data is relevant to understanding the potential and limitations of its application. This study assesses the validity of two government lists of food retailer locations and types by comparing them to direct field observations, including an assessment of whether pre-classification of the d...

  12. Characterization of the Temporal-Spatial Variability of Trans-Atlantic Dust Transport Based on CALIPSO Lidar Measurements

    Science.gov (United States)

    Yu, Hongbin

    2015-01-01

    The trans-Atlantic dust transport has important implications for human and ecosystem health, the terrestrial and oceanic biogeochemical cycle, weather systems, and climate. A reliable assessment of these influences requires the characterization of dust distributions in three dimensions and over long time periods. We provide an observation-based multiyear estimate of trans-Atlantic dust transport by using a 7-year (2007 - 2013) lidar record from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) in both cloud-free and above-cloud conditions. We estimate that on a basis of the 7-year average and integration over 10S - 30N, 182 Tg a-1 dust leaves the coast of North Africa at 15W, of which 132 Tg a-1 and 43 Tg a-1 reaches 35W and 75W, respectively. These flux estimates have an overall known uncertainty of (45 - 70). The 7-year average of dust deposition into the Amazon Basin is estimated to be 28 (8 - 48) Tg a-1 or 29 (8 - 50) kg ha-1 a-1. This imported dust could provide about 0.022 (0.006 - 0.037) Tg P of phosphorus per year, equivalent to 23 (7 - 39) g P ha-1 a-1 to fertilize the Amazon rainforest, which is comparable to the loss of phosphorus to rainfall. Significant seasonal variations are observed in both the magnitude of total dust transport and its meridional and vertical distributions. The observed large interannual variability of annual dust transport is highly anti-correlated with the prior-year Sahel Precipitation Index. Comparisons of CALIPSO measurements with surface-based observations and model simulations will also be discussed.

  13. The large scale dust distribution in the inner galaxy

    Science.gov (United States)

    Hauser, M. G.; Dwek, E.; Gezari, D.; Silverberg, R.; Kelsall, T.; Stier, M.; Cheung, L.

    1983-01-01

    Initial results are presented from a new large-scale survey of the first quadrant of the galactic plane at wavelengths of 160, 260, and 300 microns. The submillimeter wavelength emission, interpreted as thermal radiation by dust grains, reveals an optically thin disk of angular width about 0.09 deg (FWHM) with a mean dust temperature of 23 K and significant variation of the dust mass column density. Comparison of the dust column density with the gas column density inferred from CO survey data shows a striking spatial correlation. The mean luminosity per hydrogen atom is found to be 2.5 x 10 to the -30th W/H, implying a radiant energy density in the vicinity of the dust an order of magnitude larger than in the solar neighborhood. The data favor dust in molecular clouds as the dominant submillimeter radiation source.

  14. Block-sparse beamforming for spatially extended sources in a Bayesian formulation

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Fernandez Grande, Efren; Gerstoft, Peter

    2016-01-01

    sources, but cannot capture spatially extended sources. The DOA estimation problem is formulated in a Bayesian framework where regularization is imposed through prior information on the source spatial distribution which is then reconstructed as the maximum a posteriori estimate. A composite prior......Direction-of-arrival (DOA) estimation refers to the localization of sound sources on an angular grid from noisy measurements of the associated wavefield with an array of sensors. For accurate localization, the number of angular look-directions is much larger than the number of sensors, hence...... is introduced, which simultaneously promotes a piecewise constant profile and sparsity in the solution. Simulations and experimental measurements show that this choice of regularization provides high-resolution DOA estimation in a general framework, i.e., in the presence of spatially extended sources....

  15. Low-spatial-coherence broadband fiber source for speckle free imaging

    CERN Document Server

    Redding, Brandon; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-01-01

    We designed and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at {\\lambda}=1055 nm with a full-width half-maximum bandwidth of 74 nm. The emission is distributed among as many as ~70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  16. Low-spatial-coherence high-radiance broadband fiber source for speckle free imaging.

    Science.gov (United States)

    Redding, Brandon; Ahmadi, Peyman; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-10-15

    We design and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at λ=1055  nm, with a full width at half-maximum bandwidth of 74 nm. The emission is distributed among as many as ∼70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full-field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  17. Emergency hospital visits in association with volcanic ash, dust storms and other sources of ambient particles: a time-series study in Reykjavík, Iceland.

    Science.gov (United States)

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-04-13

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; "volcanic ash", "dust storms", or "other sources" (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: -0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution.

  18. Change of the Asian dust source region deduced from the relationship between anthropogenic radionuclides in surface soil and precipitation in Mongolia

    Directory of Open Access Journals (Sweden)

    Y. Igarashi

    2011-01-01

    Full Text Available The Asian dust source region may be expanding primarily as a result of recent climate change, especially during the 2000s. This change was investigated by examining anthropogenic radionuclides contained in surface soil samples from Mongolia. Surface soil was globally labeled by radioactive fallout from nuclear testing during the late 1950s and early 1960s. There are no current direct sources for anthropogenic radionuclides in the air, so the radionuclides in the atmosphere are mainly carried by dust from wind-blown surface soil, that is, aeolian dust. Asian dust carries 90Sr, 137Cs, and other anthropogenic radionuclides; the heaviest deposition occurs in spring and has been recorded in Japan since the early 1990s. The composition of anthropogenic radionuclides in atmospheric depositions would be affected by a change in the dust source. Previous studies of atmospheric depositions at long-term monitoring sites (e.g. in Tsukuba, Japan have detected changes in the 137Cs/90Sr ratio and in the specific activity of the radionuclides. These changes in the composition of observed atmospheric depositions should be a reflection for a change in the climatic conditions of the dust source region. To investigate this dust source change, a field survey for radionuclides (90Sr and 137Cs in surface soil samples was conducted in September 2007 in the eastern and southern regions of Mongolia, where dust storms have occurred more frequently since 2000. It was found that specific activities of both radionuclides as well as the 137Cs/90Sr ratio in the surface soil correlated well with annual average precipitation in the Mongolian desert-steppe zone. The higher specific activities and the higher 137Cs/90Sr ratio were found in the grassland region with the greater precipitation. This finding suggests that the increased specific activities and the activity ratio

  19. Determining spatial variability in PM 2.5 source impacts across Detroit, MI

    Science.gov (United States)

    Duvall, Rachelle M.; Norris, Gary A.; Burke, Janet M.; Olson, David A.; Vedantham, Ram; Williams, Ron

    2012-02-01

    Intra-urban variability in air pollution source impacts was investigated using receptor modeling of daily speciated PM 2.5 measurements collected at residential outdoor locations across Detroit, MI (Wayne County) as part of the Detroit Exposure and Aerosol Research Study (DEARS) during summer and winter from 2004 to 2006. Six areas were selected for the residential monitoring in the DEARS to capture impacts from different sources including local industry, motor vehicles, and upwind regional sources. PM 2.5 measurements were also collected at the Allen Park, MI Chemical Speciation Network (CSN) site for comparison with the residential outdoor sites. Sources impacting PM 2.5 were quantified using the EPA Chemical Mass Balance Model (CMB 8.2). Published source profiles were used as input to CMB along with a mixed industrial profile and a steel manufacturing profile obtained by applying the EPA Positive Matrix Factorization Model (PMF 4.0) to CSN data from a Midwestern U.S. site with industrial sources similar to Detroit. Major PM 2.5 sources impacting the Allen Park and residential monitoring areas during DEARS included motor vehicles (24-36% by mass), secondary sulfate/coal combustion (17-35%), secondary nitrate (16-37%) and organic matter (17-21%). Road dust, steel manufacturing, and mixed industrial sources contributed less than 11% by mass. CMB source contribution estimates for Allen Park during the DEARS generally compared well to CMB estimates from the collocated year-long CSN measurements using the same source profiles. CMB source contributions during DEARS showed similar contributions across the residential monitoring areas for secondary sulfate/coal combustion and secondary nitrate consistent with regional impacts for these sources. Contributions from motor vehicles, steel manufacturing, and mixed industrial sources varied across the DEARS monitoring areas, indicating impacts from local sources within the Detroit airshed that may not be well characterized by

  20. Spatial and Semantic Validation of Secondary Food Source Data

    Directory of Open Access Journals (Sweden)

    Anders K. Lyseen

    2014-02-01

    Full Text Available Governmental and commercial lists of food retailers are often used to measure food environments and foodscapes for health and nutritional research. Information about the validity of such secondary food source data is relevant to understanding the potential and limitations of its application. This study assesses the validity of two government lists of food retailer locations and types by comparing them to direct field observations, including an assessment of whether pre-classification of the directories can reduce the need for field observation. Lists of food retailers were obtained from the Central Business Register (CVR and the Smiley directory. For each directory, the positive prediction value (PPV and sensitivity were calculated as measures of completeness and thematic accuracy, respectively. Standard deviation was calculated as a measure of geographic accuracy. The effect of the pre-classification was measured through the calculation of PPV, sensitivity and negative prediction value (NPV. The application of either CVR or Smiley as a measure of the food environment would result in a misrepresentation. The pre-classification based on the food retailer names was found to be a valid method for identifying approximately 80% of the food retailers and limiting the need for field observation.

  1. Study on source rock potential and source rocks spatial distribution in the Manghan Faulted Sag, Kailu Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Manghan Faulted Sag is an exploratory target area in Kailu Basin. In order to determine its exploration prospect, the effectiveness of its source rocks is evaluated by organic geochemical behavior analysis of the samples, and their distributions are predicted using trace integration seismic inversion technology. Studies on their organic matter abundance, type and maturity indicate that the source rocks in the Sag have great generating potentials. Furthermore, it is found that, based on the spatial distribution predication, the source rocks in the Sag are well developed. Therefore, the Sag has a promising prospect for exploration.

  2. Dechlorane Plus in house dust from E-waste recycling and urban areas in South China: sources, degradation, and human exposure.

    Science.gov (United States)

    Wang, Jing; Tian, Mi; Chen, She-Jun; Zheng, Jing; Luo, Xiao-Jun; An, Tai-Cheng; Mai, Bi-Xian

    2011-09-01

    Dechlorane Plus (DP) was measured in house dust from e-waste recycling and from urban and rural areas of South China, with geometric mean concentrations of 604, 14.5, and 2.89 ng/g, respectively. Dechlorane Plus in house dust in the e-waste area originated from e-waste recycling activities, whereas household appliances served as a major source of DP in urban house dust. The isomer ratios (f(anti) ) of DP in most dust samples from the e-waste area were significantly lower than those in the urban and rural dust samples and the commercial mixture. Several [-1Cl + H] and [-2Cl + 2H] dechloro-DPs were identified in house dust from the e-waste area, and an a-Cl(11) DP was qualified with concentrations of <55.1 ng/g. Photolytic degradation experiments were conducted by exposing anti-DP, syn-DP, and commercial DP solutions to ultraviolet (UV) light. The slight difference in isomeric half-life derived by photodegradation, as well as the lower f(anti) values in the e-waste combusted residue, suggest a significant influence of isomer-specific thermal degradation of DP during e-waste burning on isomer composition in house dust in the e-waste area. The average estimated daily intakes (EDIs) of DP via house dust ranged from 0.06 to 30.2 ng/d for adults and 0.14 to 121 ng/d for toddlers in the studied area. The average EDIs of a-Cl(11) DP for adults and toddlers in the e-waste area were 0.07 and 0.18 ng/d, respectively.

  3. Lead and other elements in house dust of Japanese residences--source of lead and health risks due to metal exposure.

    Science.gov (United States)

    Yoshinaga, Jun; Yamasaki, Kumiko; Yonemura, Ayumi; Ishibashi, Yuri; Kaido, Takaya; Mizuno, Kodai; Takagi, Mai; Tanaka, Atsushi

    2014-06-01

    The levels of 25 elements in house dust collected from 100 general Japanese residences were measured. Factor analysis was applied on the multi-element data to explore source of Pb (median concentration 49.1 mg/kg) in house dust. Six factors were extracted and Pb was found to have great loading on the fifth factor with Sb and Sn, suggesting solder (Sn), and plastic and metals (Sb) may be the sources of Pb in the house dust of Japanese residences. No significant loading was found on soil-related factors indicating non-significant contribution of Pb in track-in soil. Seven heavy metals (Cd, Cu, Mo, Pb, Sb, Sn, and Zn) were found in house dust at >10 times more condensed than crustal abundance. Health risk of these elements to children via the ingestion of house dust was estimated based on the comparison with tolerable daily intake and found to be non-significant for most of the elements.

  4. Spatial distribution of polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDDs/Fs) in dust, soil, sediment and health risk assessment from an intensive electronic waste recycling site in Southern China.

    Science.gov (United States)

    Hu, Jianfang; Xiao, Xiao; Peng, Ping'an; Huang, Weilin; Chen, Deyi; Cai, Ying

    2013-10-01

    Workshop dust, soil and sediment samples were collected to investigate the level and spatial distribution of PCDDs/Fs at an intensive electronic waste (e-waste) recycling site in Southern China, and also to characterize the dioxin emission in different e-waste recycling procedures. The concentrations of total PCDDs/Fs ranged from 1866 to 234292 ng kg(-1) for the dust samples, from 3187 to 63998 ng kg(-1) dry wt for the top soils, and 33718 ng kg(-1) for the surface sediment. All the samples were characterized by abnormally high concentrations of OCDD and an extremely low portion of PCDFs. Different e-waste recycling procedures may generate different congener profiles. Open burning and dismantling were the two procedures emitting relatively higher concentrations of PCDDs/Fs in this case, indicating that low-tech recycling operations were one of the major contributors of PCDDs/Fs to the environment. The variation and distinction of the concentrations and homologue/congener profiles among different environmental matrices reveal the characteristics of contaminant environmental behavior and fate during the transportation from "source" to "sink". Daily intake of PCDDs/Fs through soil ingestion and dermal absorption was negligible, but the rough estimated total PCDD/F intake dose far exceeded the tolerance daily intake value of 4 pg-TEQ per kg per day recommended by WHO, indicating that residents in Longtang were at a high risk of exposure to dioxins, especially children.

  5. Street Dust: Source and Sink of Heavy Metals To Urban Environment

    Directory of Open Access Journals (Sweden)

    Ayrault S.

    2013-04-01

    Full Text Available Air-transferred solid material accumulated for 40 years in different places in an urban area, Grenoble city, France. An appropriate fractionation procedure allowed to separate: 1 a coarse inorganic fraction, 2 a coarse organic fraction, 3 a slowly depositing organo-clay fraction and 4 very fine particles. The composition of each fraction was determined for 20 elements and for isotopic lead signature. The organo-clay fraction was especially rich in Ag, Cd, Co, Cr, Ni and Ti. The sand fraction showed very high concentrations specifically in Cu, Pb and Fe. In contrast, Cd and Zn were mainly accumulated in the coarse organic fraction. The SEM-EDX study of the coarse inorganic fraction showed the presence of red particles associating Pb and Fe, black particles rich in Cu and typical fly ashes originating mostly from iron industry. This sand fraction is suspected to contribute to the contamination of the organo-clay fraction through adsorption. The Pb-Fe contamination likely originates from the neighbouring road surface contaminated by car traffic for several decades. The 206Pb/207Pb ratio showed that these street dust samples may contain up to 50% of lead originated from leaded gasoline additives, twelve years after their prohibition. All these features clearly differ from the composition found for the deposit on tree bark in the same place. These results demonstrate that the deposition over several decades is a very complex phenomenon which requires multi-techniques investigations to be understood thoroughly. They also show that large dense particles which can only be transported on a limited distance by high magnitude events may play a major role in the long-term contamination of urban soils.

  6. Phosphorus in the aerosols over oceans transported offshore from China to the Arctic Ocean:Speciation, spatial distribution, and potential sources

    Institute of Scientific and Technical Information of China (English)

    SUN Chen; XIE Zhouqing; KANG Hui; YU Juan

    2015-01-01

    Atmospheric aerosol samples were collected from July to September 2008 onboard a round-trip cruise over the Eastern China Sea, Japan Sea, Western North Pacific Ocean, and the Arctic Ocean (31.1°N–85.18°N, 122.48°E–146.18°W). Total phosphorus (TP) and total inorganic phosphorus (TIP) were analyzed. The organic phosphorus (OP) was calculated by subtracting TIP from TP. Average concentrations of TP in the East Asia, Western North Paciifc and Arctic Ocean were 7.90±6.45, 6.87±6.66 and 7.13±6.76 ng∙m-3, while TIP levels were 6.67±5.02, 6.07±6.58, and 6.23±5.96 along the three regions. TP and TIP levels varied considerably both spatially and temporally over the study extent. TIP was found to be the dominant species in most samples, accounting for 86.6% of TP on average. OP was also a signiifcant fraction of TP due to the primary biogenic aerosol (PBA) contribution. The phosphorus in the atmospheric aerosol over the Arctic Ocean had a higher concentration than previous model simulations. Source apportionment analysis indicates that dust is an important phosphorus source which can be globally transported, and thus dust aerosol may be an important nutrient source in some remote regions.

  7. Dusting the Archives of Childhood: Child Welfare Records as Historical Sources

    Science.gov (United States)

    Vehkalahti, Kaisa

    2016-01-01

    Using administrative sources in the history of education and childhood involves a range of methodological and ethical considerations. This article discusses these problems, as well as the role of archives and archival policies in preserving history and shaping our understanding of past childhoods. Using Finnish child welfare archives from the…

  8. MEG source localization of spatially extended generators of epileptic activity: comparing entropic and hierarchical bayesian approaches.

    Directory of Open Access Journals (Sweden)

    Rasheda Arman Chowdhury

    Full Text Available Localizing the generators of epileptic activity in the brain using Electro-EncephaloGraphy (EEG or Magneto-EncephaloGraphy (MEG signals is of particular interest during the pre-surgical investigation of epilepsy. Epileptic discharges can be detectable from background brain activity, provided they are associated with spatially extended generators. Using realistic simulations of epileptic activity, this study evaluates the ability of distributed source localization methods to accurately estimate the location of the generators and their sensitivity to the spatial extent of such generators when using MEG data. Source localization methods based on two types of realistic models have been investigated: (i brain activity may be modeled using cortical parcels and (ii brain activity is assumed to be locally smooth within each parcel. A Data Driven Parcellization (DDP method was used to segment the cortical surface into non-overlapping parcels and diffusion-based spatial priors were used to model local spatial smoothness within parcels. These models were implemented within the Maximum Entropy on the Mean (MEM and the Hierarchical Bayesian (HB source localization frameworks. We proposed new methods in this context and compared them with other standard ones using Monte Carlo simulations of realistic MEG data involving sources of several spatial extents and depths. Detection accuracy of each method was quantified using Receiver Operating Characteristic (ROC analysis and localization error metrics. Our results showed that methods implemented within the MEM framework were sensitive to all spatial extents of the sources ranging from 3 cm(2 to 30 cm(2, whatever were the number and size of the parcels defining the model. To reach a similar level of accuracy within the HB framework, a model using parcels larger than the size of the sources should be considered.

  9. Display of the complex degree of coherence due to quasi-monochromatic spatially incoherent sources.

    Science.gov (United States)

    Michalski, M; Sicre, E E; Rabal, H J

    1985-12-01

    A method for displaying the complex degree of coherence (CDC) of a quasi-monochromatic spatially incoherent source is proposed. The phase of the CDC is encoded in a method similar to that used in interferometric imaging with incoherent light. The method is based on Fourier analysis of the speckle pattern that appears when a diffuser is illuminated with the partially coherent field whose CDC is to be displayed. In addition, an intensity pattern that resembles the spatial distribution of the incoherent source can also be obtained.

  10. [Polychlorinated biphenyls in house dust at an e-waste site and urban site in the Pearl River Delta, southern China: sources and human exposure and health risks].

    Science.gov (United States)

    Zhu, Zhi-Cheng; Chen, She-Jun; Ding, Nan; Wang, Jing; Luo, Xiao-Jun; Mai, Bi-Xian

    2014-08-01

    Polychlorinated biphenyls (PCBs) were measured in house dust from an e-waste site and urban site in the Pearl River Delta, southern China. The PCB concentrations in house dust at the e-waste site ranged from 12.4 to 87 765 ng x g(-1), with an average of 10 167 ng x g(-1). There was no significant difference in the PCB concentrations between indoor and outdoor dust. The PCB homologue pattern was dominated by tri-, penta-, hexa-, and tetra-CBs, which was not similar to that in Chinese technical PCB product. There was also no significant difference in the PCB compositions between indoor and outdoor dust. PCB sources in house dust at the e-waste site were apportioned by chemical mass balance (CMB) model. The results showed that the PCBs were derived primarily from Aroclor 1262 (36.7% ), Aroclor 1254 (26.7%), Aroclor 1242 (21.4%), and Aroclor 1248 (18.5%). The daily exposure doses were 42, 17, and 2.9 ng x (kg x d)(-1) for toddlers, children/adolescents, and adults in the e-waste area, respectively. Risk assessment indicated that the hazard quotients were higher than 1 for toddlers and children/adolescents indicating adverse effects for them. The lifetime average excess carcinogenic risk for population in the e-waste area was 4.5 x 10(-5), within the acceptable range of U. S. Environmental Protection Agency. The mean concentrations of PCBs in house dust in Guangzhou was 48.7 ng x g(-1). The low PCB level is consistent with the fact that technical PCBs were not widely used in China in the past. The risks of exposure to PCBs via house dust in Guangzhou are very low.

  11. Spatial Magnetic Analysis of Dusts from Sealed Urban Surfaces for Estimation of Particulate Matter Accumulation in the Mega-city of Mumbai, India

    Science.gov (United States)

    Nathani, B.; Blaha, U.; Das, P. K.; Kannan, D.

    2011-12-01

    Spatial magnetic susceptibility analysis provides a tool for fast characterization of the impact of road traffic and industrial activity on the accumulation of harmful particulate matter in road dust in the Mega-city of Mumbai. The collection of 262 dust samples from the "Bombay Arc", an area that stretches bow-like from Mumbai peninsula -located between the Arabian Sea and Thane Creek- towards the newly settled areas of Navi Mumbai some 50 km in the east, enables for comparison of 6 independent areas of in total ~110 km^2 with rather heterogeneous settlement structures. The various kinds of settlement structures range from residential areas to industrial zones along the "Bombay Arc" including all categories of minor and major roads. Spatial magnetic analysis preferably reveals low values of ~80×10^-7 m^3kg^-1 in the coastal areas, e.g. at the southern tip of Mumbai peninsula and on the eastern shore of Thane Creek in the Nerul and Vashi area, suggesting lower magnetic particle loads of anthropogenic origin in these districts. High values of MS of ~250×10^-7 m^3kg^-1 are observed along main roads with high traffic density such as the Eastern-Express-Highway, the Sion-Panvel-Highway and locally in industrial zones. The MS patterns clearly show that road traffic on main roads has the most significant impact on the enhancement of values within the "Bombay Arc". The highest value in the entire area of ~1000×10^-7 m^3kg^-1 was detected in the Taloja industrial zone in Navi Mumbai. An E-W transect across the heart of Mumbai peninsula reveals high MS values close to the still active dock yards in the E and low values in the residential and recreation areas in the W towards the Arabian Sea. The profile reveals an expressed and stable gradient. Strong impact of dust particles from roads on the adjacent curbside is expressed by characteristic MS profiles, revealing increased values up to 5 m from the rim of the road. Such pattern is seen along surface MS profiles

  12. Block-sparse beamforming for spatially extended sources in a Bayesian formulation

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Fernandez Grande, Efren; Gerstoft, Peter

    2016-01-01

    Direction-of-arrival (DOA) estimation refers to the localization of sound sources on an angular grid from noisy measurements of the associated wavefield with an array of sensors. For accurate localization, the number of angular look-directions is much larger than the number of sensors, hence......, the problem is underdetermined and requires regularization. Traditional methods use an L2-norm regularizer, which promotes minimum-power (smooth) solutions, while regularizing with L1-norm promotes sparsity. Sparse signal reconstruction improves the resolution in DOA estimation in the presence of a few point...... sources, but cannot capture spatially extended sources. The DOA estimation problem is formulated in a Bayesian framework where regularization is imposed through prior information on the source spatial distribution which is then reconstructed as the maximum a posteriori estimate. A composite prior...

  13. Identification and spatial patterns of coastal water pollution sources based on GIS and chemometric approach

    Institute of Scientific and Technical Information of China (English)

    ZHOU Feng; GUO Huai-cheng; LIU Yong; HAO Ze-jia

    2007-01-01

    Comprehensive and joint applications of GIS and chemometric approach were applied in identification and spatial patterns of coastal water pollution sources with a large data set (5 years (2000-2004), 17 parameters) obtained through coastal water monitoring of Southern Water Control Zone in Hong Kong. According to cluster analysis the pollution degree was significantly different between September-next May (the 1st period) and June-August (the 2nd period). Based on these results, four potential pollution sources, such as organic/eutrophication pollution, natural pollution, mineral/anthropic pollution and fecal pollution were identified by factor analysis/principal component analysis. Then the factor scores of each monitoring site were analyzed using inverse distance weighting method, and the results indicated degree of the influence by various potential pollution sources differed among the monitoring sites. This study indicated that hybrid approach was useful and effective for identification of coastal water pollution source and spatial pattern.

  14. Investigating dust trapping in transition disks with millimeter-wave polarization

    CERN Document Server

    Pohl, A; Pinilla, P; Dullemond, C P; Henning, Th; Birnstiel, T

    2016-01-01

    Spatially resolved polarized (sub-)mm emission has been observed for example in the protoplanetary disk around HL Tau. Magnetically aligned grains are commonly interpreted as the source of polarization. However, self-scattering by large dust grains with a high enough albedo is another polarization mechanism, becoming a compelling method independent of the spectral index to constrain the dust grain size in protoplanetary disks. We study the dust polarization at mm wavelength in the dust trapping scenario proposed for transition disks, when a giant planet opens a gap in the disk. We investigate the characteristic polarization patterns and their dependence on disk inclination, dust size evolution, planet position, and observing wavelength. We combine two-dimensional hydrodynamical simulations of planet-disk interactions with self-consistent dust growth models. These size-dependent dust density distributions are used for follow-up three-dimensional radiative transfer calculations to predict the polarization degre...

  15. Interplanetary dust particles collected from the stratosphere: Physical, chemical, and mineralogical properties and implications for their sources

    Science.gov (United States)

    Flynn, George J.

    1994-01-01

    The suggestion that significant quantities of interplanetary dust are produced by both main-belt asteroids and comets is based on the Infrared Astronomical Satellite (IRAS) detection of dust trails or bands associated with these objects. Gravitational focusing strongly biases all near-Earth collections of interplanetary dust in favor of particles with the lowest geocentric velocities, that is the dust from main-belt asteroids spiraling into the Sun under the influence of Poynting-Robertson radiation drag. The major dust bands in the main-belt appear to be associated with the catastrophic disruptions which produced the Eos, Themis and Koronis families of asteroids. If dust particles are produced in the catastrophic collision process, then Poynting-Robertson radiation drag is such an efficient transport mechanism from the main-belt to 1 AU that near-Earth collections of interplanetary dust should include, and perhaps be dominated by, this material. Interplanetary dust particles from 5 to 100 micrometers in diameter have been recovered from the stratosphere of the Earth by NASA sampling aircraft since the mid-1970s. The densities of a large fraction of these interplanetary dust particles are significantly lower than the densities of their constituent silicate mineral phases, indicating significant porosites. The majority of the particles are chemically and mineralogically similar to, but not identical to, the carbonaceous chondrite meteorites. Most stony interplanetary dust particles have carbon contents exceeding those of Allende, a carbonaceous chondrite meteorite having a low albedo. Higher albedo particles corresponding to S-type asteroids are underrepresented or absent from the stratospheric collections, and primitive carbonaceous particles seem to be overrepresented in the stratospheric collections compared to the fraction of main-belt asteroids classified as primitive. This suggests that much of the interplanetary dust may be generated by a stochastic process

  16. Dust storms come to central and southwestern China, too: implications from a major dust event in Chongqing

    Directory of Open Access Journals (Sweden)

    Q. Zhao

    2009-12-01

    Full Text Available Dust storms from major Asian sources are usually carried by northwesterly or westerly winds over northern and southeastern China to the Pacific Ocean. These pathways leave central and southwestern China nearly free of incursions. But a strong dust event on 5–6 May 2005 was captured in a 15-month series of weekly filter samples of PM2.5 at three sites in Chongqing. It illustrated that desert dust can be transported to this region, and sometimes strongly. Annual PM2.5 and dust were similar at the three sites, but higher than in simultaneous samples in Beijing. High correlations of dust concentration were found between the cites during spring, indicating that Asian dust affects a broader swath of China than is often realized. During the event, the concentrations of mineral dust were high at all sites (20–30 μg m−3; 15%–20% of PM2.5 in Chongqing, and 15 μg m−3; 20%–30% of PM2.5 in Beijing, and were part of a broader spring maximum. The proportions of crustal elements and pollution-derived components such as Pb, SO42−, and organic carbon indicated that the sources for this dust differed from Beijing. The dust was considerably enriched in Ca and Mg, characteristic of western deserts, whereas Beijing's dust had the lower Ca and Mg of eastern deserts. This observation agrees with synoptic patterns and back-trajectories. Driven by a cold air outbreak from the northwest, dust from the western Gobi Desert was transported at lower altitudes (<2 km above ground level, while dust from the Takla Makan Desert was transported to Chongqing at higher altitudes. Desert dust can also be important to wide areas of China during the cold season, since almost all the weekly dust peaks in the two cities coincided with extensive dust emissions in source regions. These findings collectively suggest that the amount of Asian-dust in China has been underestimated both

  17. Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siyu; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Zhongwei; Bi, Jianrong; Zhang, Wu; Shi, Jinsen; Yang, Lei; Li, Deshuai; Li, Jinxin

    2014-12-01

    The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust mass balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.

  18. EEG/MEG Source Reconstruction with Spatial-Temporal Two-Way Regularized Regression

    KAUST Repository

    Tian, Tian Siva

    2013-07-11

    In this work, we propose a spatial-temporal two-way regularized regression method for reconstructing neural source signals from EEG/MEG time course measurements. The proposed method estimates the dipole locations and amplitudes simultaneously through minimizing a single penalized least squares criterion. The novelty of our methodology is the simultaneous consideration of three desirable properties of the reconstructed source signals, that is, spatial focality, spatial smoothness, and temporal smoothness. The desirable properties are achieved by using three separate penalty functions in the penalized regression framework. Specifically, we impose a roughness penalty in the temporal domain for temporal smoothness, and a sparsity-inducing penalty and a graph Laplacian penalty in the spatial domain for spatial focality and smoothness. We develop a computational efficient multilevel block coordinate descent algorithm to implement the method. Using a simulation study with several settings of different spatial complexity and two real MEG examples, we show that the proposed method outperforms existing methods that use only a subset of the three penalty functions. © 2013 Springer Science+Business Media New York.

  19. EEG source reconstruction reveals frontal-parietal dynamics of spatial conflict processing

    NARCIS (Netherlands)

    Cohen, M.X.; Ridderinkhof, K.R.

    2013-01-01

    Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processin

  20. Aerosol structure and vertical distribution in a multi-source dust region

    Institute of Scientific and Technical Information of China (English)

    Jie Zhang; Qiang Zhang; Congguo Tang; Yongxiang Han

    2012-01-01

    The vertical distribution of aerosols was directly observed under various atmospheric conditions in the free troposphere using surface micro-pulse lidar(MPLA)at the Zhangye Station(39.08°N,100.27°E)in western China in the spring of 2008.The study shows that the aerosol distribution over Zhangye can be vertically classified into upper,middle and lower layers with altitudes of 4.5 to 9 km,2.5 to 4.5 km,and less than 2.5 km,respectively.The aerosol in the upper layer originated from the external sources at higher altitude regions,from far desert regions upwind of Zhangye or transported from higher atmospheric layers by free convection,and the altitude of this aerosol layer decreased with time; the aerosols in the middle and lower layers originated from both external and local sources.The aerosol extinction coefficients in the upper and lower layers decreased with altitude,whereas the coefficient in the middle layer changed only slightly,which suggests that aerosol mixing occurs in the middle layer.The distribution of aerosols with altitude has three features:a single peak that forms under stable atmospheric conditions,an exponential decrease with altitude that occurs under unstable atmospheric conditions,and slight change in the mixed layer.Due to the impact of the top of the atmospheric boundary layer,the diurnal variation in the aerosol extinction coefficient has a single peak,which is higher in the afternoon and lower in the morning.

  1. Spatial structure and scale feature of the atmospheric pollution source impact of city agglomeration

    Institute of Scientific and Technical Information of China (English)

    XU; Xiangde; ZHOU; Xiuji; SHI; Xiaohui

    2005-01-01

    The spatial structure and multi-scale feature of the atmospheric pollution influence domain of Beijing and its peripheral areas (a rapidly developed city agglomeration) is dissected and analyzed in this paper on the basis of the atmospheric pollution dynamic-chemical process observation data of the urban building ensemble boundary layer of the Beijing City Air Pollution Observation Experiment (BECAPEX) in winter (February) and summer (August) 2003, and relevant meteorological elements and satellite retrieval aerosol optical depth (AOD), etc. comprehensive data with the dynamic-statistical integrated analysis of "point-surface" spatial structure. Results show that there existed significant difference in the contribution of winter/summer different pollution emission sources to the component character of atmospheric pollution, and the principal component analysis (PCA) results of statistical model also indicate that SO2 and NOX dominated in the component structure of winter aerosol particle; instead, CO and NOX dominated in summer. Surface layer atmospheric dynamic and thermal structures and various pollutant species at the upper boundary of building ensembles at urban different observational sites of Beijing in winter and summer showed an "in-phase" variation and its spatial scale feature of "influence domain". The power spectrum analysis (PSA) shows that the period spectrum of winter/summer particle concentration accorded with those of atmospheric wind field: the longer period was dominative in winter, but the shorter period in summer, revealing the impact of the seasonal scale feature of winter/summer atmospheric general circulation on the period of atmospheric pollution variations. It is found that from analyzing urban area thermal heterogeneity that the multiscale effect of Beijing region urban heat island (UHI) was associated with the heterogeneous expansion of tall buildings area. In urban atmospheric dynamical and thermal characteristic spatial structures, the

  2. The spatial, spectral and polarization properties of solar flare X-ray sources

    CERN Document Server

    Jeffrey, Natasha L S

    2014-01-01

    X-rays are a valuable diagnostic tool for the study of high energy accelerated electrons. Bremsstrahlung X-rays produced by, and directly related to, high energy electrons accelerated during a flare, provide a powerful diagnostic tool for determining both the properties of the accelerated electron distribution, and of the flaring coronal and chromospheric plasmas. This thesis is specifically concerned with the study of spatial, spectral and polarization properties of solar flare X-ray sources via both modelling and X-ray observations using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Firstly, a new model is presented, accounting for finite temperature, pitch angle scattering and initial pitch angle injection. This is developed to accurately infer the properties of the acceleration region from the observations of dense coronal X-ray sources. Moreover, examining how the spatial properties of dense coronal X-ray sources change in time, interesting trends in length, width, position, number density ...

  3. In-duct identification of a rotating sound source with high spatial resolution

    Science.gov (United States)

    Heo, Yong-Ho; Ih, Jeong-Guon; Bodén, Hans

    2015-11-01

    To understand and reduce the flow noise generation from in-duct fluid machines, it is necessary to identify the acoustic source characteristics precisely. In this work, a source identification technique, which can identify the strengths and positions of the major sound radiators in the source plane, is studied for an in-duct rotating source. A linear acoustic theory including the effects of evanescent modes and source rotation is formulated based on the modal summation method, which is the underlying theory for the inverse source reconstruction. A validation experiment is conducted on a duct system excited by a loudspeaker in static and rotating conditions, with two different speeds, in the absence of flow. Due to the source rotation, the measured pressure spectra reveal the Doppler effect, and the amount of frequency shift corresponds to the multiplication of the circumferential mode order and the rotation speed. Amplitudes of participating modes are estimated at the shifted frequencies in the stationary reference frame, and the modal amplitude set including the effect of source rotation is collected to investigate the source behavior in the rotating reference frame. By using the estimated modal amplitudes, the near-field pressure is re-calculated and compared with the measured pressure. The obtained maximum relative error is about -25 and -10 dB for rotation speeds at 300 and 600 rev/min, respectively. The spatial distribution of acoustic source parameters is restored from the estimated modal amplitude set. The result clearly shows that the position and magnitude of the main sound source can be identified with high spatial resolution in the rotating reference frame.

  4. Atmospheric Processing of Iron-Containing Mineral Dust Aerosol: A Major Source of Bioavailable Iron to Ocean Life

    Science.gov (United States)

    Rubasinghege, G. R. S.; Hurub, O. A.

    2015-12-01

    In the present day, it has become more apparent that redox reactions involving mineral dust are of great interest, especially for Fe-containing mineral dust, as they transported and deposited into certain regions of the ocean that dissolved iron is often a limiting nutrient for ocean life. Given that heterogeneous reactions of Fe-containing mineral dust with acidic gases and their precursors, i.e. HNO3, dimethyl sulfide( DMS), lead to lower pH environments, the amount of bioavailable iron can increase as they are transported through the atmosphere. The current work focuses on chemical and photochemical processing of Fe-containing mineral dust particles in the presence of HNO3, SO2 and DMS under atmospherically relevant conditions. Here, various spectroscopic methods are combined with dissolution measurements to investigate atmospheric processing of iron containing aerosol dust, with a specific focus on mineralogy and environmental conditions, i.e. pH, relative humidity, temperature and solar flux. Ilmenite (FeTiO3) is used as one of the proxies for Fe-containing minerals that have enough complexity to mimic the mineral dust, yet simple enough to know the details of the reaction pathways. During these studies, above factors are found to play significant roles in the dissolution of iron from mineral dust aerosol. More importantly, data suggest that presence of titanium in the lattice structure of ilmenite enhances iron dissolution, at least by 3-fold in a comparison with hematite. Further, growth and activity of ocean diatoms (Cyclotella meneghiniana) are monitored in the presence of Fe-containing mineral dust under the same conditions. Here, diatoms are added to the reactors containing pre-dissolved iron from a prior 48hr reaction. Results show a high correlation between the growth of diatoms and the amount of bioavailable from iron containing minerals. The current study thus highlights these important, yet unconsidered, factors in the atmospheric processing of iron

  5. Data assimilation of dust aerosol observations for the CUACE/dust forecasting system

    Directory of Open Access Journals (Sweden)

    T. Niu

    2008-07-01

    Full Text Available A data assimilation system (DAS was developed for the Chinese Unified Atmospheric Chemistry Environment – Dust (CUACE/Dust forecast system and applied in the operational forecasts of sand and dust storm (SDS in spring 2006. The system is based on a three dimensional variational method (3D-Var and uses extensively the measurements of surface visibility (phenomena and dust loading retrieval from the Chinese geostationary satellite FY-2C. By a number of case studies, the DAS was found to provide corrections to both under- and over-estimates of SDS, presenting a major improvement to the forecasting capability of CUACE/Dust in the short-term variability in the spatial distribution and intensity of dust concentrations in both source regions and downwind areas. The seasonal mean Threat Score (TS over the East Asia in spring 2006 increased from 0.22 to 0.31 by using the data assimilation system, a 41% enhancement. The forecast results with DAS usually agree with the dust loading retrieved from FY-2C and visibility distribution from surface meteorological stations, which indicates that the 3D-Var method is very powerful by the unification of observation and numerical model to improve the performance of forecast model.

  6. Factors influencing the spatial extent of mobile source air pollution impacts: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Levy Jonathan I

    2007-05-01

    Full Text Available Abstract Background There has been growing interest among exposure assessors, epidemiologists, and policymakers in the concept of "hot spots", or more broadly, the "spatial extent" of impacts from traffic-related air pollutants. This review attempts to quantitatively synthesize findings about the spatial extent under various circumstances. Methods We include both the peer-reviewed literature and government reports, and focus on four significant air pollutants: carbon monoxide, benzene, nitrogen oxides, and particulate matter (including both ultrafine particle counts and fine particle mass. From the identified studies, we extracted information about significant factors that would be hypothesized to influence the spatial extent within the study, such as the study type (e.g., monitoring, air dispersion modeling, GIS-based epidemiological studies, focus on concentrations or health risks, pollutant under study, background concentration, emission rate, and meteorological factors, as well as the study's implicit or explicit definition of spatial extent. We supplement this meta-analysis with results from some illustrative atmospheric dispersion modeling. Results We found that pollutant characteristics and background concentrations best explained variability in previously published spatial extent estimates, with a modifying influence of local meteorology, once some extreme values based on health risk estimates were removed from the analysis. As hypothesized, inert pollutants with high background concentrations had the largest spatial extent (often demonstrating no significant gradient, and pollutants formed in near-source chemical reactions (e.g., nitrogen dioxide had a larger spatial extent than pollutants depleted in near-source chemical reactions or removed through coagulation processes (e.g., nitrogen oxide and ultrafine particles. Our illustrative dispersion model illustrated the complex interplay of spatial extent definitions, emission rates

  7. Spatial Regression and Prediction of Water Quality in a Watershed with Complex Pollution Sources.

    Science.gov (United States)

    Yang, Xiaoying; Liu, Qun; Luo, Xingzhang; Zheng, Zheng

    2017-08-16

    Fast economic development, burgeoning population growth, and rapid urbanization have led to complex pollution sources contributing to water quality deterioration simultaneously in many developing countries including China. This paper explored the use of spatial regression to evaluate the impacts of watershed characteristics on ambient total nitrogen (TN) concentration in a heavily polluted watershed and make predictions across the region. Regression results have confirmed the substantial impact on TN concentration by a variety of point and non-point pollution sources. In addition, spatial regression has yielded better performance than ordinary regression in predicting TN concentrations. Due to its best performance in cross-validation, the river distance based spatial regression model was used to predict TN concentrations across the watershed. The prediction results have revealed a distinct pattern in the spatial distribution of TN concentrations and identified three critical sub-regions in priority for reducing TN loads. Our study results have indicated that spatial regression could potentially serve as an effective tool to facilitate water pollution control in watersheds under diverse physical and socio-economical conditions.

  8. A contrast source method for nonlinear acoustic wave fields in media with spatially inhomogeneous attenuation.

    Science.gov (United States)

    Demi, L; van Dongen, K W A; Verweij, M D

    2011-03-01

    Experimental data reveals that attenuation is an important phenomenon in medical ultrasound. Attenuation is particularly important for medical applications based on nonlinear acoustics, since higher harmonics experience higher attenuation than the fundamental. Here, a method is presented to accurately solve the wave equation for nonlinear acoustic media with spatially inhomogeneous attenuation. Losses are modeled by a spatially dependent compliance relaxation function, which is included in the Westervelt equation. Introduction of absorption in the form of a causal relaxation function automatically results in the appearance of dispersion. The appearance of inhomogeneities implies the presence of a spatially inhomogeneous contrast source in the presented full-wave method leading to inclusion of forward and backward scattering. The contrast source problem is solved iteratively using a Neumann scheme, similar to the iterative nonlinear contrast source (INCS) method. The presented method is directionally independent and capable of dealing with weakly to moderately nonlinear, large scale, three-dimensional wave fields occurring in diagnostic ultrasound. Convergence of the method has been investigated and results for homogeneous, lossy, linear media show full agreement with the exact results. Moreover, the performance of the method is demonstrated through simulations involving steered and unsteered beams in nonlinear media with spatially homogeneous and inhomogeneous attenuation.

  9. Generation of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators

    Science.gov (United States)

    Hyde, Milo W.; Bose-Pillai, Santasri; Voelz, David G.; Xiao, Xifeng

    2016-12-01

    A simple and flexible optical system for generating electromagnetic or vector partially coherent sources or beams is presented. The alternative design controls field amplitude (beam shape), coherence, and polarization using only spatial light modulators. This improvement makes the apparatus simpler to construct and significantly increases the flexibility of vector partially coherent source generators by allowing many different types of sources to be produced without changing the physical setup. The system's layout and theoretical foundations are thoroughly discussed. The utility and flexibility of the proposed system are demonstrated by producing a vector Schell-model and non-Schell-model source. The experimental results are compared to theoretical predictions to validate the design. Lastly, design aspects, which must be considered when building a vector partially coherent source generator for a specific application, are discussed.

  10. Planck intermediate results. L. Evidence for spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB $B$-mode analysis

    CERN Document Server

    Aghanim, N; Aumont, J; Baccigalupi, C; Ballardini, M; Banday, A J; Barreiro, R B; Bartolo, N; Basak, S; Benabed, K; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bracco, A; Burigana, C; Calabrese, E; Cardoso, J -F; Chiang, H C; Colombo, L P L; Combet, C; Comis, B; Crill, B P; Curto, A; Cuttaia, F; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Di Valentino, E; Dickinson, C; Diego, J M; Doré, O; Douspis, M; Ducout, A; Dupac, X; Dusini, S; Efstathiou, G; Elsner, F; Enßlin, T A; Eriksen, H K; Falgarone, E; Fantaye, Y; Finelli, F; Frailis, M; Fraisse, A A; Franceschi, E; Frolov, A; Galeotta, S; Galli, S; Ganga, K; Génova-Santos, R T; Gerbino, M; Ghosh, T; Giard, M; González-Nuevo, J; Górski, K M; Gregorio, A; Gruppuso, A; Gudmundsson, J E; Hansen, F K; Helou, G; Herranz, D; Hivon, E; Huang, Z; Jaffe, A H; Jones, W C; Keihänen, E; Keskitalo, R; Kisner, T S; Krachmalnicoff, N; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Lattanzi, M; Lawrence, C R; Jeune, M Le; Levrier, F; Liguori, M; Lilje, P B; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maggio, G; Maino, D; Mandolesi, N; Mangilli, A; Maris, M; Martin, P G; Martínez-González, E; Matarrese, S; Mauri, N; McEwen, J D; Melchiorri, A; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Molinari, D; Moneti, A; Montier, L; Morgante, G; Moss, A; Naselsky, P; Nørgaard-Nielsen, H U; Oxborrow, C A; Pagano, L; Paoletti, D; Partridge, B; Patrizii, L; Perdereau, O; Perotto, L; Pettorino, V; Piacentini, F; Plaszczynski, S; Polenta, G; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renzi, A; Rocha, G; Rossetti, M; Roudier, G; Rubiño-Martín, J A; Ruiz-Granados, B; Salvati, L; Sandri, M; Savelainen, M; Scott, D; Sirignano, C; Sirri, G; Stanco, L; Suur-Uski, A -S; Tauber, J A; Tenti, M; Toffolatti, L; Tomasi, M; Tristram, M; Trombetti, T; Valiviita, J; Vansyngel, J; Van Tent, F; Vielva, P; Wandelt, B D; Wehus, I K; Zacchei, A; Zonca, A

    2016-01-01

    The characterization of the Galactic foregrounds has been shown to be the main obstacle in the challenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution, and its potential impact on the determination of the tensor-to-scalar ratio. We use the correlation ratio of the $C_\\ell^{BB}$ angular power spectra between the 217- and 353-GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is margina...

  11. The spiral galaxy M33 mapped in the FIR by ISOPHOT: A spatially resolved study of the warm and cold dust

    CERN Document Server

    Hippelein, H; Tuffs, R J; Lemke, D; Stickel, M; Klaas, U; Völk, H J

    2003-01-01

    The Sc galaxy M33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170mue. The spatial resolution of these FIR maps allows the separation of spiral arms and interarm regions and the isolation of a large number of star-forming regions. The spectral energy distribution in the FIR indicates a superposition of two components, a warm one originating from dust at ~45K, and a cold one, at ~16K. The warm component is concentrated towards the spiral arms and the star-forming regions, and is likely heated by the UV radiation from OB stars. The cold component is more smoothly distributed over the disk, and heated by the diffuse interstellar radiation. For the about 60 star-forming regions detected the H-alpha/FIR flux ratio increases significantly with the distance from the galaxy center, probably due to decreasing extinction. An anti-correlation of F_Ha/F_60 with F_170 suggests the intrinsic extinction to be related to the cold dust surface brightness according to A_V/S_170~0.03mag/MJy*sr. For the tota...

  12. Sources of Free and Open Source Spatial Data for Natural Disasters and Principles for Use in Developing Country Contexts

    Science.gov (United States)

    Taylor, Faith E.; Malamud, Bruce D.; Millington, James D. A.

    2016-04-01

    Access to reliable spatial and quantitative datasets (e.g., infrastructure maps, historical observations, environmental variables) at regional and site specific scales can be a limiting factor for understanding hazards and risks in developing country settings. Here we present a 'living database' of >75 freely available data sources relevant to hazard and risk in Africa (and more globally). Data sources include national scientific foundations, non-governmental bodies, crowd-sourced efforts, academic projects, special interest groups and others. The database is available at http://tinyurl.com/africa-datasets and is continually being updated, particularly in the context of broader natural hazards research we are doing in the context of Malawi and Kenya. For each data source, we review the spatiotemporal resolution and extent and make our own assessments of reliability and usability of datasets. Although such freely available datasets are sometimes presented as a panacea to improving our understanding of hazards and risk in developing countries, there are both pitfalls and opportunities unique to using this type of freely available data. These include factors such as resolution, homogeneity, uncertainty, access to metadata and training for usage. Based on our experience, use in the field and grey/peer-review literature, we present a suggested set of guidelines for using these free and open source data in developing country contexts.

  13. A rainfall design method for spatial flood risk assessment: considering multiple flood sources

    Science.gov (United States)

    Jiang, X.; Tatano, H.

    2015-08-01

    Information about the spatial distribution of flood risk is important for integrated urban flood risk management. Focusing on urban areas, spatial flood risk assessment must reflect all risk information derived from multiple flood sources: rivers, drainage, coastal flooding etc. that may affect the area. However, conventional flood risk assessment deals with each flood source independently, which leads to an underestimation of flood risk in the floodplain. Even in floodplains that have no risk from coastal flooding, flooding from river channels and inundation caused by insufficient drainage capacity should be considered simultaneously. For integrated flood risk management, it is necessary to establish a methodology to estimate flood risk distribution across a floodplain. In this paper, a rainfall design method for spatial flood risk assessment, which considers the joint effects of multiple flood sources, is proposed. The concept of critical rainfall duration determined by the concentration time of flooding is introduced to connect response characteristics of different flood sources with rainfall. A copula method is then adopted to capture the correlation of rainfall amount with different critical rainfall durations. Rainfall events are designed taking advantage of the copula structure of correlation and marginal distribution of rainfall amounts within different critical rainfall durations. A case study in the Otsu River Basin, Osaka prefecture, Japan was conducted to demonstrate this methodology.

  14. A rainfall design method for spatial flood risk assessment: considering multiple flood sources

    Directory of Open Access Journals (Sweden)

    X. Jiang

    2015-08-01

    Full Text Available Information about the spatial distribution of flood risk is important for integrated urban flood risk management. Focusing on urban areas, spatial flood risk assessment must reflect all risk information derived from multiple flood sources: rivers, drainage, coastal flooding etc. that may affect the area. However, conventional flood risk assessment deals with each flood source independently, which leads to an underestimation of flood risk in the floodplain. Even in floodplains that have no risk from coastal flooding, flooding from river channels and inundation caused by insufficient drainage capacity should be considered simultaneously. For integrated flood risk management, it is necessary to establish a methodology to estimate flood risk distribution across a floodplain. In this paper, a rainfall design method for spatial flood risk assessment, which considers the joint effects of multiple flood sources, is proposed. The concept of critical rainfall duration determined by the concentration time of flooding is introduced to connect response characteristics of different flood sources with rainfall. A copula method is then adopted to capture the correlation of rainfall amount with different critical rainfall durations. Rainfall events are designed taking advantage of the copula structure of correlation and marginal distribution of rainfall amounts within different critical rainfall durations. A case study in the Otsu River Basin, Osaka prefecture, Japan was conducted to demonstrate this methodology.

  15. Ibmdbpy-spatial : An Open-source implementation of in-database geospatial analytics in Python

    Science.gov (United States)

    Roy, Avipsa; Fouché, Edouard; Rodriguez Morales, Rafael; Moehler, Gregor

    2017-04-01

    As the amount of spatial data acquired from several geodetic sources has grown over the years and as data infrastructure has become more powerful, the need for adoption of in-database analytic technology within geosciences has grown rapidly. In-database analytics on spatial data stored in a traditional enterprise data warehouse enables much faster retrieval and analysis for making better predictions about risks and opportunities, identifying trends and spot anomalies. Although there are a number of open-source spatial analysis libraries like geopandas and shapely available today, most of them have been restricted to manipulation and analysis of geometric objects with a dependency on GEOS and similar libraries. We present an open-source software package, written in Python, to fill the gap between spatial analysis and in-database analytics. Ibmdbpy-spatial provides a geospatial extension to the ibmdbpy package, implemented in 2015. It provides an interface for spatial data manipulation and access to in-database algorithms in IBM dashDB, a data warehouse platform with a spatial extender that runs as a service on IBM's cloud platform called Bluemix. Working in-database reduces the network overload, as the complete data need not be replicated into the user's local system altogether and only a subset of the entire dataset can be fetched into memory in a single instance. Ibmdbpy-spatial accelerates Python analytics by seamlessly pushing operations written in Python into the underlying database for execution using the dashDB spatial extender, thereby benefiting from in-database performance-enhancing features, such as columnar storage and parallel processing. The package is currently supported on Python versions from 2.7 up to 3.4. The basic architecture of the package consists of three main components - 1) a connection to the dashDB represented by the instance IdaDataBase, which uses a middleware API namely - pypyodbc or jaydebeapi to establish the database connection via

  16. On the Source of the Dust Extinction in Type Ia Supernovae and the Discovery of Anomalously Strong Na I Absorption

    CERN Document Server

    Phillips, M M; Morrell, Nidia; Burns, Christopher R; Cox, Nick L J; Foley, Ryan J; Karakas, Amanda I; Patat, F; Sternberg, A; Williams, R E; Gal-Yam, A; Hsiao, E Y; Leonard, D C; Persson, Sven E; Stritzinger, Maximilian; Thompson, I B; Campillay, Abdo; Contreras, Carlos; Folatelli, Gastón; Freedman, Wendy L; Hamuy, Mario; Roth, Miguel; Shields, Gregory A; Suntzeff, Nicholas B; Chomiuk, Laura; Ivans, Inese I; Madore, Barry F; Penprase, B E; Perley, Daniel; Preston, G Pignata G; Soderberg, Alicia M

    2013-01-01

    High-dispersion observations of the Na I D 5890, 5896 and K I 7665, 7699 interstellar lines, and the diffuse interstellar band at 5780 Angstroms in the spectra of 32 Type Ia supernovae are used as an independent means of probing dust extinction. We show that the dust extinction of the objects where the diffuse interstellar band at 5780 Angstroms is detected is consistent with the visual extinction derived from the supernova colors. This strongly suggests that the dust producing the extinction is predominantly located in the interstellar medium of the host galaxies and not in circumstellar material associated with the progenitor system. One quarter of the supernovae display anomalously large Na I column densities in comparison to the amount of dust extinction derived from their colors. Remarkably, all of the cases of unusually strong Na I D absorption correspond to "Blueshifted" profiles in the classification scheme of Sternberg et al. (2011). This coincidence suggests that outflowing circumstellar gas is resp...

  17. 40 CFR 63.1445 - What work practice standards must I meet for my fugitive dust sources?

    Science.gov (United States)

    2010-07-01

    ... include, but are not limited to, transfer of material from one conveyor belt to another and transfer of... transporting bulk quantities of fugitive dust materials. Paved roads and parking areas that are not used by...

  18. Spatial relationship of organized rotational and focal sources in human atrial fibrillation to autonomic ganglionated plexi.

    Science.gov (United States)

    Baykaner, Tina; Zografos, Theodoros A; Zaman, Junaid A B; Pantos, Ioannis; Alhusseini, Mahmood; Navara, Rachita; Krummen, David E; Narayan, Sanjiv M; Katritsis, Demosthenes G

    2017-08-01

    One approach to improve ablation for atrial fibrillation (AF) is to focus on physiological targets including focal or rotational sources or ganglionic plexi (GP). However, the spatial relationship between these potential mechanisms has never been studied. We tested the hypothesis that rotors and focal sources for AF may co-localize with ganglionated plexi (GP). We prospectively identified locations of AF rotors and focal sources, and correlated these to GP sites in 97 consecutive patients (age 59.9±11.4, 73% persistent AF). AF was recorded with 64-pole catheters with activation/phase mapping, and related to anatomic GP sites on electroanatomic maps. AF sources arose in 96/97 (99%) patients for 2.6±1.4 sources per patient (left atrium: 1.7±0.9 right atrium: 1.1±0.8), each with an area of 2-3cm(2). On area analyses, the probability of an AF source randomly overlapping a GP area was 26%. Left atrial sources were seen in 94 (97%) patients, in whom ≥1 source co-localized with GP in 75 patients (80%; psources were more likely to colocalize with left vs right GPs (p65, diabetes; psources in the left atrium often colocalize with regions of autonomic innervation. Studies should define if the role of AF sources differs by their anatomical location. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Spatial distribution and source identification of trace elements in topsoil from heavily industrialized region, Aliaga, Turkey.

    Science.gov (United States)

    Kara, Melik; Dumanoğlu, Yetkin; Altıok, Hasan; Elbir, Tolga; Odabası, Mustafa; Bayram, Abdurrahman

    2014-10-01

    Topsoil samples (n = 40) were collected from a heavily industrialized region in Turkey. The region includes several scrap processing iron-steel plants with electric arc furnaces (EAFs), a petroleum refinery, a petrochemical complex, steel rolling mills, a natural gas-fired power plant, ship-breaking yards and very dense transportation activities. The region has undergone a rapid transition from an agricultural region to a heavily industrialized region in the last three decades. Collected soil samples were analyzed for 48 trace elements using inductively coupled plasma-mass spectrometry (ICP-MS). The elemental distribution pattern in the region indicated that Nemrut area with dense iron-steel production activities was a hotspot for elemental pollution. In addition to crustal elements, concentrations of anthropogenic trace elements (i.e., Fe, Zn, Pb, Mn, Cu, Cd, Cr and Mo) were very high in the area influencing many parts of the region. Elemental compositions of fugitive sources polluting the soil (i.e., paved and unpaved roads, slag piles, EAFs filter dust piles and coal piles) were also determined. The methods (enrichment factors [EFs] and the index of geoaccumulation [Igeo]) used for determination of pollution status of soil showed that Cr, Ag, Zn, As and Pb were the strongly contaminating elements for the region. Principal component analysis (PCA) clearly indicated that anthropogenic sources (steel production, refinery and petrochemical processes and traffic) were important sources in this region.

  20. Distribution of chemical elements in attic dust as reflection of their geogenic and anthropogenic sources in the vicinity of the copper mine and flotation plant.

    Science.gov (United States)

    Balabanova, Biljana; Stafilov, Trajče; Sajn, Robert; Bačeva, Katerina

    2011-08-01

    The main aim of this article was to assess the atmospheric pollution with heavy metals due to copper mining Bučim near Radoviš, the Republic of Macedonia. The open pit and mine waste and flotation tailings are continually exposed to open air, which leads to winds carrying the fine particles into the atmosphere. Samples of attic dust were examined as historical archives of mine emissions, with the aim of elucidating the pathways of pollution. Dust was collected from the attics of 29 houses, built between 1920 and 1970. Nineteen elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Li, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were analyzed by atomic emission spectrometry with inductively coupled plasma. The obtained values of the investigated elements in attic dust samples were statistically processed using nonparametric and parametric analysis. Factor analysis revealed three factors governing the source of individual chemical elements. Two of them grouping Ca, Li, Mg, Mn, and Sr (Factor 1) and Co, Cr, and Ni (Factor 2) can be characterized as geogenic. The third factor grouping As, Cu, and Pb is anthropogenic and mirrors dust fallout from mining operation and from flotation tailings. Maps of areal deposition were prepared for this group of elements, from which correlation of these anthropogenic born elements was confirmed.

  1. An extended-source spatial acquisition process based on maximum likelihood criterion for planetary optical communications

    Science.gov (United States)

    Yan, Tsun-Yee

    1992-01-01

    This paper describes an extended-source spatial acquisition process based on the maximum likelihood criterion for interplanetary optical communications. The objective is to use the sun-lit Earth image as a receiver beacon and point the transmitter laser to the Earth-based receiver to establish a communication path. The process assumes the existence of a reference image. The uncertainties between the reference image and the received image are modeled as additive white Gaussian disturbances. It has been shown that the optimal spatial acquisition requires solving two nonlinear equations to estimate the coordinates of the transceiver from the received camera image in the transformed domain. The optimal solution can be obtained iteratively by solving two linear equations. Numerical results using a sample sun-lit Earth as a reference image demonstrate that sub-pixel resolutions can be achieved in a high disturbance environment. Spatial resolution is quantified by Cramer-Rao lower bounds.

  2. Spatial resolution limits for the localization of noise sources using direct sound mapping

    Science.gov (United States)

    Fernandez Comesaña, D.; Holland, K. R.; Fernandez-Grande, E.

    2016-08-01

    One of the main challenges arising from noise and vibration problems is how to identify the areas of a device, machine or structure that produce significant acoustic excitation, i.e. the localization of main noise sources. The direct visualization of sound, in particular sound intensity, has extensively been used for many years to locate sound sources. However, it is not yet well defined when two sources should be regarded as resolved by means of direct sound mapping. This paper derives the limits of the direct representation of sound pressure, particle velocity and sound intensity by exploring the relationship between spatial resolution, noise level and geometry. The proposed expressions are validated via simulations and experiments. It is shown that particle velocity mapping yields better results for identifying closely spaced sound sources than sound pressure or sound intensity, especially in the acoustic near-field.

  3. Adjoint-optimization algorithm for spatial reconstruction of a scalar source

    Science.gov (United States)

    Wang, Qi; Hasegawa, Yosuke; Meneveau, Charles; Zaki, Tamer

    2016-11-01

    Identifying the location of the source of passive scalar transported in a turbulent environment based on remote measurements is an ill-posed problem. A conjugate-gradient algorithm is proposed, and relies on eddy-resolving simulations of both the forward and adjoint scalar transport equations to reconstruct the spatial distribution of the source. The formulation can naturally accommodate measurements from multiple sensors. The algorithm is evaluated for scalar dispersion in turbulent channel flow (Reτ = 180). As the distance between the source and sensor increases, the accuracy of the source recovery deteriorates due to diffusive effects. Improvement in performance is demonstrated for higher Prantl numbers and also with increasing number of sensors. This study is supported by the National Science Foundation (Grant CNS 1461870).

  4. Spatially differentiated and source-specific population exposure to ambient urban air pollution

    Science.gov (United States)

    Zou, Bin; Wilson, J. Gaines; Zhan, F. Benjamin; Zeng, Yongnian

    Models assessing exposure to air pollution often focus on macro-scale estimates of exposure to all types of sources for a particular pollutant across an urban study area. While results based on these models may aid policy makers in identifying larger areas of elevated exposure risk, they often do not differentiate the proportion of population exposure attributable to different polluting sources (e.g. traffic or industrial). In this paper, we introduce a population exposure modeling system that integrates air dispersion modeling, Geographic Information Systems (GIS), and population exposure techniques to spatially characterize a source-specific exposure to ambient air pollution for an entire urban population at a fine geographical scale. By area, total population exposure in Dallas County in 2000 was more attributable to vehicle polluting sources than industrial polluting sources at all levels of exposure. Population exposure was moderately correlated with vehicle sources ( r = 0.440, p air quality assessments must incorporate more than industrial or vehicle polluting sources-based population exposure values alone, but should consider multiple sources. The population exposure modeling system proposed in this study shows promise for use by municipal authorities, policy makers, and epidemiologists in evaluating and controlling the quality of the air in the process of urban planning and mitigation measures.

  5. pH-dependent dissolved iron speciation of dust collected in dust source region%不同提取液中源区沙尘溶解性铁价态组成特征

    Institute of Scientific and Technical Information of China (English)

    罗云汉; 吴枫; 曹军骥; 郭晓

    2016-01-01

    Background, aim, and scope About 30% of the world oceans like the Equatorial Pacific and the Southern Oceans are comprised of high-nutrient low-chlorophyll (HNLC) regions where phytoplankton growth is limited by bioavailable iron(Fe) supply. It is believed that increased bioavailable Fe supply to these regions will stimulate phytoplankton growth, leading to enhanced atmospheric CO2 sequestration and nitrogen ifxation by the ocean, which can have profound impacts on climate. Mineral dust originated from the world semi-arid and arid regions is the dominant source of Fe to the remote oceans. Direct ifeld measurements reported Fe solubility of mineral dust ranging from less than 0.1%to as much as 80%with higher solubility values generally observed over remote parts of the oceans, implying that atmospheric processing can increase the Fe solubility during dust transport. To understand how atmospheric process will influence Fe dissolution behavior of mineral dust, Fe solubility and dissolved Fe speciation of mineral dust in typical atmospheric solutions were investigated. Materials and methods In April 2015, four dust Total Suspended Particle (TSP) samples were collected at the Tengger Desert, a well-known Asian dust source region. A quarter of the dust iflter sample was extracted with ammonium acetate (pH 4.7) and sulfuric acid (pH 2) to simulate Fe dissolution in the rainwater and acidic aerosol water, respectively. Dissolved Fe and Fe2+in the extraction solution were measured colorimetrically using the Ferrozine method. Total Fe on the iflter was determined with X-Ray Fluorescence. Results Fe solubility was 4.17%(2.30%—5.74%) in the ammonium acetate and 6.13%(4.72%—7.27%) in the sulfuric acid. Large difference in soluble iron speciation was observed in the two solutions. In the ammonium acetate, Fe3+was the dominant species accounting for 76.7%—98.3%of the total dissolved iron and Fe2+ only constituted a minor part (1.73%—23.3%). In the sulfuric acid, Fe2+ was

  6. EEG source reconstruction reveals frontal-parietal dynamics of spatial conflict processing.

    Directory of Open Access Journals (Sweden)

    Michael X Cohen

    Full Text Available Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processing. Human subjects performed a Simon task, in which conflict was induced by incongruence between spatial location and response hand. We found an early (∼200 ms post-stimulus conflict modulation in stimulus-contralateral parietal gamma (30-50 Hz, followed by a later alpha-band (8-12 Hz conflict modulation, suggesting an early detection of spatial conflict and inhibition of spatial location processing. Inter-regional connectivity analyses assessed via cross-frequency coupling of theta (4-8 Hz, alpha, and gamma power revealed conflict-induced shifts in cortical network interactions: Congruent trials (relative to incongruent trials had stronger coupling between frontal theta and stimulus-contrahemifield parietal alpha/gamma power, whereas incongruent trials had increased theta coupling between medial frontal and lateral frontal regions. These findings shed new light into the large-scale network dynamics of spatial conflict processing, and how those networks are shaped by oscillatory interactions.

  7. EEG source reconstruction reveals frontal-parietal dynamics of spatial conflict processing.

    Science.gov (United States)

    Cohen, Michael X; Ridderinkhof, K Richard

    2013-01-01

    Cognitive control requires the suppression of distracting information in order to focus on task-relevant information. We applied EEG source reconstruction via time-frequency linear constrained minimum variance beamforming to help elucidate the neural mechanisms involved in spatial conflict processing. Human subjects performed a Simon task, in which conflict was induced by incongruence between spatial location and response hand. We found an early (∼200 ms post-stimulus) conflict modulation in stimulus-contralateral parietal gamma (30-50 Hz), followed by a later alpha-band (8-12 Hz) conflict modulation, suggesting an early detection of spatial conflict and inhibition of spatial location processing. Inter-regional connectivity analyses assessed via cross-frequency coupling of theta (4-8 Hz), alpha, and gamma power revealed conflict-induced shifts in cortical network interactions: Congruent trials (relative to incongruent trials) had stronger coupling between frontal theta and stimulus-contrahemifield parietal alpha/gamma power, whereas incongruent trials had increased theta coupling between medial frontal and lateral frontal regions. These findings shed new light into the large-scale network dynamics of spatial conflict processing, and how those networks are shaped by oscillatory interactions.

  8. Coherent Sources Direction Finding and Polarization Estimation with Various Compositions of Spatially Spread Polarized Antenna Arrays

    CERN Document Server

    Yuan, Xin

    2014-01-01

    Various compositions of sparsely polarized antenna arrays are proposed in this paper to estimate the direction-of-arrivals (DOAs) and polarizations of multiple coherent sources. These polarized antenna arrays are composed of one of the following five sparsely-spread sub-array geometries: 1) four spatially-spread dipoles with three orthogonal orientations, 2) four spatially-spread loops with three orthogonal orientations, 3) three spatially-spread dipoles and three spatially-spread loops with orthogonal orientations, 4) three collocated dipole-loop pairs with orthogonal orientations, and 5) a collocated dipole-triad and a collocated loop-triad. All the dipoles/loops/pairs/triads in each sub-array can also be sparsely spaced with the inter-antenna spacing far larger than a half-wavelength. Only one dimensional spatial-smoothing is used in the proposed algorithm to derive the two-dimensional DOAs and polarizations of multiple cross-correlated signals. From the simulation results, the sparse array composed of dip...

  9. Derivation of an observation-based map of North African dust emission

    Energy Technology Data Exchange (ETDEWEB)

    Evan, Amato T.; Fiedler, Stephanie; Zhao, Chun; Menut, Laurent; Schepanski, Kerstin; Flamant, C.; Doherty, Owen

    2015-03-01

    Changes in the emission, transport and deposition of aeolian dust have profound effects on regional climate, so that characterizing the lifecycle of dust in observations and improving the representation of dust in global climate models is necessary. A fundamental aspect of characterizing the dust cycle is quantifying surface dust fluxes, yet no spatially explicit estimates of this flux exist for the World’s major source regions. Here we present a novel technique for creating a map of the annual mean emitted dust flux for North Africa based on retrievals of dust storm frequency from the Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the relationship between dust storm frequency and emitted mass flux derived from the output of five models that simulate dust. Our results suggest that 64 (±16)% of all dust emitted from North Africa is from the Bodélé depression, and that 13 (±3)% of the North African dust flux is from a depression lying in the lee of the Aïr and Hoggar Mountains, making this area the second most important region of emission within North Africa.

  10. Quantifying the Heating Sources for Mid-infrared Dust Emissions in Galaxies: The Case of M 81

    CERN Document Server

    Lu, Nanyao; Boselli, A; Baes, M; Wu., H; Madden, S C; De Looze, I; Rémy-Ruyer, A; Boquien, M; Wilson, C D; Galametz, M; Lam, M I; Cooray, A; Spinoglio, L; Zhao, Y

    2014-01-01

    With the newly available SPIRE images at 250 and 500 micron from Herschel Space Observatory, we study quantitative correlations over a sub-kpc scale among three distinct emission components in the interstellar medium of the nearby spiral galaxy M 81 (NGC 3031): (a) $I_{8}$ or $I_{24}$, the surface brightness of the mid-infrared emission observed in the Spitzer IRAC 8 or MIPS 24 micron band, with $I_8$ and $I_{24}$ being dominated by the emissions from Polycyclic Aromatic Hydrocarbons (PAHs) and very small grains (VSGs) of dust, respectively; (b) $I_{500}$, that of the cold dust continuum emission in the Herschel SPIRE 500 micron band, dominated by the emission from large dust grains heated by evolved stars, and (c) $I_{{\\rm H}\\alpha}$, a nominal surface brightness of the H$\\alpha$ line emission, from gas ionized by newly formed massive stars. The results from our correlation study, free from any assumption on or modeling of dust emissivity law or dust temperatures, present solid evidence for significant heati...

  11. Intercontinental Transport and Climatic Impact of Saharan and Sahelian Dust

    Directory of Open Access Journals (Sweden)

    N'Datchoh Evelyne Touré

    2012-01-01

    Full Text Available The Sahara and Sahel regions of Africa are important sources of dust particles into the atmosphere. Dust particles from these regions are transported over the Atlantic Ocean to the Eastern American Coasts. This transportation shows temporal and spatial variability and often reaches its peak during the boreal summer (June-July-August. The regional climate model (RegCM 4.0, containing a module of dust emission, transport, and deposition processes, is used in this study. Saharan and Sahelian dusts emissions, transports, and climatic impact on precipitations during the spring (March-April-May and summer (June-July-August were studied using this model. The results showed that the simulation were coherent with observations made by the MISR satellite and the AERONET ground stations, within the domain of Africa (Banizoumba, Cinzana, and M’Bour and Ragged-point (Barbados Islands. The transport of dust particles was predominantly from North-East to South-West over the studied period (2005–2010. The seasonality of dust plumes’ trajectories was influenced by the altitudes reached by dusts in the troposphere. The impact of dusts on climate consisted of a cooling effect both during the boreal summer and spring over West Africa (except Southern-Guinea and Northern-Liberia, Central Africa, South-America, and Caribbean where increased precipitations were observed.

  12. Spatial variation and source apportionment of water pollution in Qiantang River (China) using statistical techniques.

    Science.gov (United States)

    Huang, Fang; Wang, Xiaoquan; Lou, Liping; Zhou, Zhiqing; Wu, Jiaping

    2010-03-01

    Understanding the spatial distribution and apportioning the sources of water pollution are important in the study and efficient management of water resources. In this work, we considered data for 13 water quality variables collected during the year 2004 at 46 monitoring sites along the Qiantang River (China). Fuzzy comprehensive analysis categorized the data into three major pollution zones (low, moderate, and high) based on national quality standards for surface waters, China. Most sites classified as "low pollution zones" (LP) occurred in the main river channel, whereas those classified as "moderate and high pollution zones" (MP and HP, respectively) occurred in the tributaries. Factor analysis identified two potential pollution sources that explained 67% of the total variance in LP, two potential pollution sources that explained 73% of the total variance in MP, and three potential pollution sources that explained 80% of the total variance in HP. UNMIX was used to estimate contributions from identified pollution sources to each water quality variable and each monitoring site. Most water quality variables were influenced primarily by pollution due to industrial wastewater, agricultural activities and urban runoff. In LP, non-point source pollution such as agricultural runoff and urban runoff dominated; in MP and HP, mixed source pollution dominated. The pollution in the small tributaries was more serious than that in the main channel. These results provide information for developing better pollution control strategies for the Qiantang River.

  13. Life Cycle of Dust in the Magellanic Clouds and the Milky Way

    CERN Document Server

    Zhukovska, Svitlana

    2014-01-01

    To a great extent, our understanding of the life cycle of dust is based on the observational and theoretical studies of the Milky Way and the Magellanic Clouds, which will be the topic of this contribution. Over past years, a large volume of observations with unprecedented spatial resolution has been accumulated for the Milky Way. It permits investigations of different stages of the life cycle of dust, from its formation in stellar sources to destruction in star-forming regions and supernovae shocks. Observations of dust emission, extinction, polarisation of light, and interstellar element depletions in the solar neighbourhood provide the most accurate constraints for the reference dust models applied to study extragalactic systems. However, global spatial studies of the circumstellar and interstellar dust are complicated in the Milky Way disk because of high extinction, confusion along the line of sight and large uncertainties in distances. In contrast, the favourable location in the sky and the proximity of...

  14. High Proportions of Sub-micron Particulate Matter in Icelandic Dust Storms in 2015

    Science.gov (United States)

    Dagsson Waldhauserova, Pavla; Arnalds, Olafur; Olafsson, Haraldur; Magnusdottir, Agnes

    2017-04-01

    Iceland is extremely active dust region and desert areas of over 44,000 km2 acknowledge Iceland as the largest Arctic and European desert. Frequent dust events, up to 135 dust days annually, transport dust particles far distances towards the Arctic and Europe. Satellite MODIS pictures have revealed dust plumes exceeding 1,000 km. The annual dust deposition was calculated as 40.1 million tons yr-1. Two dust storms were measured in transverse horizontal profile about 90 km far from different dust sources in southwestern Iceland in the summer of 2015. Aerosol monitor DustTrak DRX 8533EP was used to measure PM mass concentrations corresponding to PM1, PM2.5, PM4, PM10 and the total PM15 at several places within the dust plume. Images from camera network operated by the Icelandic Road and Coastal Administration were used to estimate the visibility and spatial extent of measured dust events. A numerical simulation of surface winds was carried out with the numerical model HIRLAM with horizontal resolution of 5 km and used to calculate the total dust flux from the sources. The in situ measurements inside the dust plumes showed that aeolian dust can be very fine. The study highlights that suspended volcanic dust in Iceland causes air pollution with extremely high PM1 concentrations comparable to the polluted urban stations in Europe or Asia rather than reported dust event observations from around the world. The PM1/PM2.5 ratios are generally low during dust storms outside of Iceland, much lower than > 0.9 and PM1/PM10 ratios of 0.34-0.63 found in our study. It shows that Icelandic volcanic dust consists of higher proportion of submicron particles compared to crustal dust. The submicron particles are predicted to travel long distances. Moreover, such submicron particles pose considerable health risk because of high potential for entering the lungs. Icelandic volcanic glass has often fine pipe-vesicular structures known from asbestos and high content of heavy metals. Previous

  15. Nonuniformity correction of infrared cameras by reading radiance temperatures with a spatially nonhomogeneous radiation source

    Science.gov (United States)

    Gutschwager, Berndt; Hollandt, Jörg

    2017-01-01

    We present a novel method of nonuniformity correction (NUC) of infrared cameras and focal plane arrays (FPA) in a wide optical spectral range by reading radiance temperatures and by applying a radiation source with an unknown and spatially nonhomogeneous radiance temperature distribution. The benefit of this novel method is that it works with the display and the calculation of radiance temperatures, it can be applied to radiation sources of arbitrary spatial radiance temperature distribution, and it only requires sufficient temporal stability of this distribution during the measurement process. In contrast to this method, an initially presented method described the calculation of NUC correction with the reading of monitored radiance values. Both methods are based on the recording of several (at least three) images of a radiation source and a purposeful row- and line-shift of these sequent images in relation to the first primary image. The mathematical procedure is explained in detail. Its numerical verification with a source of a predefined nonhomogeneous radiance temperature distribution and a thermal imager of a predefined nonuniform FPA responsivity is presented.

  16. Spatial structure and scale feature of the atmospheric pollution source impact of city agglomeration

    Institute of Scientific and Technical Information of China (English)

    XU Xiangde; ZHOU Xiuji; SHI Xiaohui

    2005-01-01

    The spatial structure and multi-scale feature of the atmospheric pollution influence domain of Beijing and its peripheral areas (a rapidly developed city agglomeration) is dissected and analyzed in this paper on the basis of the atmospheric pollution dynamic-chemical process observation data of the urban building ensemble boundary layer of the Beijing City Air Pollution Observation Experiment (BECAPEX) in winter (February) and summer (August) 2003, and relevant meteorological elements and satellite retrieval aerosol optical depth (AOD), etc. comprehensive data with the dynamic-statistical integrated analysis of "point-surface" spatial structure. Results show that there existed significant difference in the contribution of winter/summer different pollution emission sources to the component character of atmospheric pollution, and the principal component analysis (PCA) results of statistical model also indicate that SO2 and NOX dominated in the component structure of winter aerosol particle; instead, CO and NOX dominated in summer. Surface layer atmospheric dynamic and thermal structures and various pollutant species at the upper boundary of building ensembles at urban different observational sites of Beijing in winter and summer showed an "in-phase" variation and its spatial scale feature of "influence domain". The power spectrum analysis (PSA) shows that the period spectrum of winter/summer particle concentration accorded with those of atmospheric wind field: the longer period was dominative in winter, but the shorter period in summer, revealing the impact of the seasonal scale feature of winter/summer atmospheric general circulation on the period of atmospheric pollution variations. It is found that from analyzing urban area thermal heterogeneity that the multiscale effect of Beijing region urban heat island (UHI) was associated with the heterogeneous expansion of tall buildings area. In urban atmospheric dynamical and thermal characteristic spatial structures, the

  17. Using the significant dust deposition event on the glaciers of Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009 to develop a method for dating and provenancing of desert dust events recorded in snow pack

    Directory of Open Access Journals (Sweden)

    M. Shahgedanova

    2012-09-01

    Full Text Available A significant desert dust deposition event occurred on Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009, where the deposited dust later appeared as a brown layer in the snow pack. An examination of dust transportation history and analysis of chemical and physical properties of the deposited dust were used to develop a new approach for high-resolution provenancing of dust deposition events recorded in snow pack using multiple independent techniques. A combination of SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived with HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours and spatial (ca. 100 km resolution. Dust, deposited on 5 May 2009, originated in the foothills of the Djebel Akhdar in eastern Libya where dust sources were activated by the intrusion of cold air from the Mediterranean Sea and Saharan low pressure system and transported to the Caucasus along the eastern Mediterranean coast, Syria and Turkey. Particles with an average diameter below 8 μm accounted for 90% of the measured particles in the sample with a mean of 3.58 μm, median 2.48 μm and the dominant mode of 0.60 μm. The chemical signature of this long-travelled dust was significantly different from the locally-produced dust and close to that of soils collected in a palaeolake in the source region, in concentrations of hematite and oxides of aluminium, manganese, and magnesium. Potential addition of dust from a secondary source in northern Mesopotamia introduced uncertainty in the provenancing of dust from this event. Nevertheless, the approach adopted here enables other dust horizons in the snowpack to be linked to specific dust transport events recorded in remote sensing and meteorological data archives.

  18. Potential Climate Effects of Dust Aerosols' over West Africa

    Science.gov (United States)

    JI, Z.; Wang, G.; Pal, J. S.; Yu, M.

    2014-12-01

    Climate in West Africa is under the influence of the West African monsoon circulation and mineral dust emitted from the Sahara desert (which is the world's largest source of mineral dust emission). Dust aerosols alter the atmospheric radiative fluxes and act as cloud condensation nuclei in the process of emission, transportation and deposition. However, our understanding regarding how dust aerosols influence the present-day and future climate of West Africa is very limited. In this study, a regional climate model RegCM4.3.4-CLM4.5 is used to investigate the potential climatic effects of dust aerosols both in present (1981-2000) and future (2081-2100) periods over WA. First, the model performance and dust climatic effects are evaluated. The contribution of dust climatic effects under RCP8.5 scenario and their confounding effects with land use change are assessed. Our results indicate that the model can reproduce with reasonable accuracy the spatial and temporal distribution of climatology, aerosol optical depth and surface concentration over WA. The shortwave radiative forcing of dust is negative in the surface and positive in the atmosphere, with greater changes in JJA and MAM compared to those in SON and DJF. Over most of West Africa, cooling is the dominant effect on temperature. Their impact on precipitation features a dipole pattern, with decrease in the north and increase in the south of West Africa. Despite the dust-induced decrease of precipitation amount, dusts cause extreme precipitation to increase. To evaluate the uncertainties surrounding our modeling results, sensitivity experiments driven by ICBC from MIROC-ESM and CESM and their dynamic downscaling results are used for comparisons. Results from these sensitivity experiments indicate that the impact of dust aerosols on present and future climate is robust.

  19. Analyzing existing conventional soil information sources to be incorporated in thematic Spatial Data Infrastructures

    Science.gov (United States)

    Pascual-Aguilar, J. A.; Rubio, J. L.; Domínguez, J.; Andreu, V.

    2012-04-01

    New information technologies give the possibility of widespread dissemination of spatial information to different geographical scales from continental to local by means of Spatial Data Infrastructures. Also administrative awareness on the need for open access information services has allowed the citizens access to this spatial information through development of legal documents, such as the INSPIRE Directive of the European Union, adapted by national laws as in the case of Spain. The translation of the general criteria of generic Spatial Data Infrastructures (SDI) to thematic ones is a crucial point for the progress of these instruments as large tool for the dissemination of information. In such case, it must be added to the intrinsic criteria of digital information, such as the harmonization information and the disclosure of metadata, the own environmental information characteristics and the techniques employed in obtaining it. In the case of inventories and mapping of soils, existing information obtained by traditional means, prior to the digital technologies, is considered to be a source of valid information, as well as unique, for the development of thematic SDI. In this work, an evaluation of existing and accessible information that constitutes the basis for building a thematic SDI of soils in Spain is undertaken. This information framework has common features to other European Union states. From a set of more than 1,500 publications corresponding to the national territory of Spain, the study was carried out in those documents (94) found for five autonomous regions of northern Iberian Peninsula (Asturias, Cantabria, Basque Country, Navarra and La Rioja). The analysis was performed taking into account the criteria of soil mapping and inventories. The results obtained show a wide variation in almost all the criteria: geographic representation (projections, scales) and geo-referencing the location of the profiles, map location of profiles integrated with edaphic

  20. Imaging a spatially confined photoacoustic source defined by a distribution of plasmonic nanoparticles

    Science.gov (United States)

    Norton, Stephen J.; Vo-Dinh, Tuan

    2012-05-01

    This paper describes the use of plasmonic nanoparticles in photoacoustic imaging. When acoustic waves are generated by thermoacoustic expansion in the fluid medium surrounding a distribution of these particles and the acoustic signals are recorded over a planar aperture, a bandlimited image of this distribution can be reconstructed. It is shown that the accessible portion of the three-dimensional spatial Fourier transform of the unknown source distribution is a spherical shell in k-space, with the core representing missing low-frequency Fourier components of the source density. When the source arises from an isolated distribution of nanoparticles, the iterative Gerchberg-Papoulis procedure can be applied to recover the low-frequency Fourier components. It is shown that this version of the photoacoustic source reconstruction problem is well suited for the use of this procedure. In this way, the fidelity of the image of the photoacoustic-generated source defined by the particle concentration can be enhanced. The procedure is illustrated using simulated data derived from a hypothetical source distribution.

  1. Perception of the Spatial Extent of the Zagora Region in Selected Cartographic Sources

    Directory of Open Access Journals (Sweden)

    Branimir Vukosav

    2015-06-01

    Full Text Available The dynamism of sociogeographic and historical processes and trends represents a key factor in the creation and uniformity of regions, and in their image and perception in the eyes of the public and scholars. As a basic geographic concept, a region is the result of all preceding and actual spatial relations arising from natural conditions, and those arising from political, administrative and economic changes. Non-formal regions such as Dalmatinska zagora, which exists solely in the consciousness of its inhabitants, owe their traditional presence in spatial perceptions and identities to a combination of all these factors. The uniformity and identity of such a region are articulated through explicit and implicit symbols, definitions and terms, and the most important among these is a geographic name or toponym. As an indicator of basic spatial relations at the time of its making, a map can be used as a source of information on spatial identities, their extent and distribution. In that sense, the presence and positioning of a toponym are the keys to discovering facts about the territoriality and contemporary perceptions of a region that it denotes. The aim of this paper is to monitor changes in the dynamics of perception of Zagora, a region in the Dalmatian hinterland, by detecting the positioning of the toponym Zagora and its variants on several maps created at different periods in history.

  2. DustPedia: A Definitive Study of Cosmic Dust in the Local Universe

    Science.gov (United States)

    Davies, J. I.; Baes, M.; Bianchi, S.; Jones, A.; Madden, S.; Xilouris, M.; Bocchio, M.; Casasola, V.; Cassara, L.; Clark, C.; De Looze, I.; Evans, R.; Fritz, J.; Galametz, M.; Galliano, F.; Lianou, S.; Mosenkov, A. V.; Smith, M.; Verstocken, S.; Viaene, S.; Vika, M.; Wagle, G.; Ysard, N.

    2017-04-01

    The European Space Agency has invested heavily in two cornerstones missions: Herschel and Planck. The legacy data from these missions provides an unprecedented opportunity to study cosmic dust in galaxies so that we can, for example, answer fundamental questions about the origin of the chemical elements, physical processes in the interstellar medium (ISM), its effect on stellar radiation, its relation to star formation and how this relates to the cosmic far-infrared background. In this paper we describe the DustPedia project, which enables us to develop tools and computer models that will help us relate observed cosmic dust emission to its physical properties (chemical composition, size distribution, and temperature), its origins (evolved stars, supernovae, and growth in the ISM), and the processes that destroy it (high-energy collisions and shock heated gas). To carry out this research, we combine the Herschel/Planck data with that from other sources of data, and provide observations at numerous wavelengths (≤slant 41) across the spectral energy distribution, thus creating the DustPedia database. To maximize our spatial resolution and sensitivity to cosmic dust, we limit our analysis to 4231 local galaxies (venergy distributions (HerBIE) and a state-of-the-art Monte Carlo photon-tracing radiative transfer model (SKIRT). In this, the first of the DustPedia papers, we describe the project objectives, data sets used, and provide an insight into the new scientific methods we plan to implement.

  3. Dust storms and loess accumulation on the Tibetan Plateau:A case study of dust event on 4 March 2003 in Lhasa

    Institute of Scientific and Technical Information of China (English)

    FANG Xiaomin; HAN Yongxiang; MA Jinghui; SONG Lianchun; YANG Shengli; ZHANG Xiaoye

    2004-01-01

    Whether the Tibetan Plateau is a significant dust source area is of great importance, because this is related to the understanding of sources, accumulation and environmental effects of dusts on the Tibetan Plateau and in the Far East-Pacific Ocean regions as well as to the evolution of coupling of the Tibetan Plateau and atmosphere-ocean continent exchange. Synoptic dynamics and remote sensing tracing of a dust storm on 3 to 5 March, 2003 in Lhasa on South Tibet demonstrate that the Tibetan Plateau possesses all factors and conditions of generating dust storms. Accom panied with this dust storm is a strong ascending stream on the Plateau which has raised various sizes of dust particles into different levels. The lifted coarse particles were largely fallen down and accumulated as loess on the eastern Tibetan Plateau, and the fine particles were translated by the west erly jet and subsided in the northern Pacific Ocean. The spatial-temporal distribution of dust-storms between years 1961 and 2000 on the Plateau shows that dust-storms mainly occur in winter and early spring with high frequency, and the path of dust storm moves gradually from south to north, which is closely coupled with the northward moving of the westerly jet from winter to spring over the Tibetan Plateau. Compared with other twelve dust source areas in China, the Tibetan Plateau is one of the key dust source areas for the long-distance transport because its high occurring frequency and elevation cause fine particles easily to be lifted into the zone of the westerly jet.

  4. Aerosol time-series measurements over the tropical Northeast Atlantic Ocean: Dust sources, elemental composition and mineralogy

    NARCIS (Netherlands)

    Patey, M.D.; Achterberg, E.P.; Rijkenberg, M.J.; Pearce, R.

    2015-01-01

    The North Atlantic receives the largest dust loading of any of the world's oceans due to its proximity to North African deserts and prevailing wind patterns. The supply of biologically important trace elements and nutrients via aerosols has an important influence on biogeochemical processes and ecos

  5. Dust events on Vatnajökull, Iceland: comparison between model results and measurements

    Science.gov (United States)

    Dragosics, Monika; Groot Zwaaftink, Christine; Thorsteinsson, Throstur; Stohl, Andreas

    2016-04-01

    Dust events in Iceland considerably influence the surface albedo and subsequently the energy balance of glaciers such as Vatnajökull. Here we study dust events on Vatnajökull based on model simulations and ground-based measurements. Possible sources of dust origin are proglacial areas and sandy deserts which cover more than 22% of Iceland. A newly developed scheme for dust mobilization is used to estimate dust emission from these sandy deserts. Driven with these emissions, a Lagrangian dispersion model, FLEXPART, is used to calculate dust concentration and deposition. The model simulations facilitate to distinguish main source areas of dust transported to the glacier. Meteorological conditions at the source locations as well as flows induced by topography will affect the spatial distribution of dust on the glacier, and not all are resolved by the meteorological data from ECMWF used to run FLEXPART (resolution 0.2 degrees or about 22 km). We aim to determine how important local effects are. Ground based data such as distributed snow samples from Vatnajökull with impurities were collected in October 2013 and 2015. Additionally, firn cores of about 8 meters depth from Brúarjökull (NE Vatnajökull), were taken in 2014 and 2015. The firn cores show pronounced dust layers in the years 2012, 2011, 2010 and 2008. These dust concentrations from firn cores and snow samples as well as time series of albedo measurements from automatic weather stations, were compared to model results. For this comparison we chose ablation seasons which are not influenced by volcanic eruptions. For these periods we explain variations in dust amounts and their spatial patterns.

  6. [Research on spatial differentiation of urban stormwater runoff quality by source area monitoring].

    Science.gov (United States)

    Li, Li-Qing; Zhu, Ren-Xiao; Guo, Shu-Gang; Yin, Cheng-Qing

    2010-12-01

    Runoff samples were collected from 14 source areas in Hanyang district during four rain events in an attempt to investigate the spatial differentiation and influencing factors of urban stormwater runoff quality. The outcomes are expected to offer practical guidance in sources control of urban runoff pollution. The results revealed that particle-bound proportion of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in stormwater runoff were 58% +/- 17%, 65% +/- 13% and 92% +/- 6%, respectively. The fractions of ammonia, nitrate and dissolved organic nitrogen were homogeneous in dissolved nitrogen composition. Urban surface function, traffic volume, land use, population density, and street sweeping practice are the main factors determining spatial differentiation of urban surface runoff quality. The highest magnitude of urban stormwater runoff pollution was expected in the old urban residential area, followed by general residential with restaurants, commercial and transport area, new developments and green land. In addition, the magnitude of road stormwater runoff pollution is positively correlated to traffic volume, in the following order: the first trunk road > the second trunk road > minor road. Street sweeping and critical source areas controls should be implemented to mitigate the adverse effects of urban stormwater runoff on receive waters.

  7. On the source of the dust extinction in type Ia supernovae and the discovery of anomalously strong Na I absorption

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M. M.; Morrell, Nidia; Hsiao, E. Y.; Campillay, Abdo; Contreras, Carlos [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Simon, Joshua D.; Burns, Christopher R.; Persson, Sven E.; Thompson, I. B.; Freedman, Wendy L. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101 (United States); Cox, Nick L. J. [Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D bus 2401, 3001 Leuven (Belgium); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Karakas, Amanda I. [Research School of Astronomy and Astrophysics, The Australian National University, Weston, ACT 2611 (Australia); Patat, F. [European Southern Observatory (ESO), Karl Schwarschild Strasse 2, D-85748, Garching bei München (Germany); Sternberg, A. [Max Planck Institute for Astrophysics, Karl Schwarzschild Strasse 1, D-85741 Garching bei München (Germany); Williams, R. E. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gal-Yam, A. [Benoziyo Center for Astrophysics, Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Leonard, D. C. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Folatelli, Gastón, E-mail: mmp@lco.cl [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo, Kashiwa 277-8583 (Japan); and others

    2013-12-10

    High-dispersion observations of the Na I D λλ5890, 5896 and K I λλ7665, 7699 interstellar lines, and the diffuse interstellar band at 5780 Å in the spectra of 32 Type Ia supernovae are used as an independent means of probing dust extinction. We show that the dust extinction of the objects where the diffuse interstellar band at 5780 Å is detected is consistent with the visual extinction derived from the supernova colors. This strongly suggests that the dust producing the extinction is predominantly located in the interstellar medium of the host galaxies and not in circumstellar material associated with the progenitor system. One quarter of the supernovae display anomalously large Na I column densities in comparison to the amount of dust extinction derived from their colors. Remarkably, all of the cases of unusually strong Na I D absorption correspond to 'Blueshifted' profiles in the classification scheme of Sternberg et al. This coincidence suggests that outflowing circumstellar gas is responsible for at least some of the cases of anomalously large Na I column densities. Two supernovae with unusually strong Na I D absorption showed essentially normal K I column densities for the dust extinction implied by their colors, but this does not appear to be a universal characteristic. Overall, we find the most accurate predictor of individual supernova extinction to be the equivalent width of the diffuse interstellar band at 5780 Å, and provide an empirical relation for its use. Finally, we identify ways of producing significant enhancements of the Na abundance of circumstellar material in both the single-degenerate and double-degenerate scenarios for the progenitor system.

  8. Extinction and dust properties in a clumpy medium

    CERN Document Server

    Scicluna, P

    2015-01-01

    (abridged) The dust content of the universe is primarily explored via its interaction with stellar photons, producing interstellar extinction. However, owing to the physical extension of the observing beam, observations may detect scattered photons, resulting in a change in the observed (or effective) extinction, depending on the spatial distribution of the dust and the resolution of the instrument. We investigate the influence of clumpy dust distributions on effective extinction toward embedded sources and those in the diffuse ISM. We use Monte Carlo radiative transfer to examine effective extinction for various geometries. By varying the number, optical depth and volume-filling factor of clumps in models of spherical shells and the diffuse ISM, we explore the evolution of extinction. Depending on the number of scattering events in the beam, the extinction curve steepens in homogeneous media and flattens in clumpy media. As a result, clumpy dust distributions can to reproduce extinction curves with arbitrary...

  9. [Soil Heavy Metal Spatial Distribution and Source Analysis Around an Aluminum Plant in Baotou].

    Science.gov (United States)

    Zhang, Lian-ke; Li, Hai-peng; Huang, Xue-min; Li, Yu-mei; Jiao, Kun-ling; Sun, Peng; Wang, Wei-da

    2016-03-15

    The soil with 500 m distance from an aluminum plant in Baotou was studied. A total of 64 soil samples were taken from the 0-5 cm, 5-20 cm, 20-40 cm and 40-60 cm layers, and the contents of Cu, Pb, Zn, Cr, Cd, Ni and Mn were tested, respectively. The correlation analysis and principal component analysis were used to identify the sources of these heavy metals in soils. The results suggested that the contents of Cu, Pb, Zn, Cr, Cd, Ni and Mn in study area were 32.9, 50.35, 69.92, 43.78, 0.54, 554.42 and 36.65 mg · kg⁻¹ respectively. All seven heavy metals tested were overweight compared with the background values of soil in Inner Mongolia. The spatial distribution of heavy metals showed that the horizontal distribution of heavy metals was obviously enriched in the southwest, while in vertical distribution, the heavy metal content (0 to 5 cm) was highest in the surface soil, and the heavy metal content decreased with increasing depth and tended to be stabilized when the depth was over 20 cm. Source analysis showed that the source of Cu, Zn, Cr and Mn might be influenced by the aluminum plant and the surrounding industrial activity. The source of Pb and Cd might be mainly related to road transportation. The source of Ni may be affected by agricultural activities and soil parent material together.

  10. Preliminary Assessment of Health Risks of Potentially Toxic Elements in Settled Dust over Beijing Urban Area

    Directory of Open Access Journals (Sweden)

    Dejun Wan

    2016-05-01

    Full Text Available To examine levels, health risks, sources, and spatial distributions of potentially toxic elements in settled dust over Beijing urban area, 62 samples were collected mostly from residential building outdoor surfaces, and their <63 μm fractions were measured for 12 potentially toxic elements. The results show that V, Cr, Mn, Co, Ni, and Ba in dust are from predominantly natural sources, whereas Cu, Zn, As, Cd, Sb, and Pb mostly originate from anthropogenic sources. Exposure to these elements in dust has significant non-cancer risks to children but insignificant to adults. Cancer risks of Cr, Co, Ni, As, and Cd via inhalation and dermal contact are below the threshold of 10−6–10−4 but As via dust ingestion shows a tolerable risk. The non-cancer risks to children are contributed mainly (75% by As, Pb, and Sb, and dominantly (92% via dust ingestion, with relatively higher risks mainly occurring in the eastern and northeastern Beijing urban areas. Although Cd, Zn, and Cu in dust are heavily affected by anthropogenic sources, their health risks are insignificant. Source appointments suggest that coal burning emissions, the dominant source of As, are likely the largest contributors to the health risk, and traffic-related and industrial emissions are also important because they contribute most of the Pb and Sb in dust.

  11. An open source platform for multi-scale spatially distributed simulations of microbial ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Segre, Daniel [Boston Univ., MA (United States)

    2014-08-14

    The goal of this project was to develop a tool for facilitating simulation, validation and discovery of multiscale dynamical processes in microbial ecosystems. This led to the development of an open-source software platform for Computation Of Microbial Ecosystems in Time and Space (COMETS). COMETS performs spatially distributed time-dependent flux balance based simulations of microbial metabolism. Our plan involved building the software platform itself, calibrating and testing it through comparison with experimental data, and integrating simulations and experiments to address important open questions on the evolution and dynamics of cross-feeding interactions between microbial species.

  12. Quantifying local-scale dust emission from the Arabian Red Sea coastal plain

    KAUST Repository

    Anisimov, Anatolii

    2017-01-23

    Dust plumes emitted from the narrow Arabian Red Sea coastal plain are often observed on satellite images and felt in local population centers. Despite its relatively small area, the coastal plain could be a significant dust source; however, its effect is not well quantified as it is not well approximated in global or even regional models. In addition, because of close proximity to the Red Sea, a significant amount of dust from the coastal areas could be deposited into the Red Sea and serve as a vital component of the nutrient balance of marine ecosystems. In the current study, we apply the offline Community Land Model version 4 (CLM4) to better quantify dust emission from the coastal plain during the period of 2009-2011. We verify the spatial and temporal variability in model results using independent weather station reports. We also compare the results with the MERRA Aerosol Reanalysis (MERRAero). We show that the best results are obtained with 1 km model spatial resolution and dust source function based on Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) measurements. We present the dust emission spatial pattern, as well as estimates of seasonal and diurnal variability in dust event frequency and intensity, and discuss the emission regime in the major dust generation hot spot areas. We demonstrate the contrasting seasonal dust cycles in the northern and southern parts of the coastal plain and discuss the physical mechanisms responsible for dust generation. This study provides the first estimates of the fine-scale spatial and temporal distribution of dust emissions from the Arabian Red Sea coastal plain constrained by MERRAero and short-term WRF-Chem simulations. The estimate of total dust emission from the coastal plain, tuned to fit emissions in MERRAero, is 7.5 ± 0.5 Mt a. Small interannual variability indicates that the study area is a stable dust source. The mineralogical composition analysis shows that the coastal plain

  13. The representation of dust transport and missing urban sources as major issues for the simulation of PM episodes in a Mediterranean area

    Directory of Open Access Journals (Sweden)

    E. Flaounas

    2009-10-01

    Full Text Available Due to its adverse effects on human health, atmospheric particulate matter (PM constitutes a growing challenge for air quality management. It is also a complex subject of study. The understanding of its atmospheric evolution is indeed made difficult by the wide number of sources and the numerous processes that govern its evolution in the troposphere. As a consequence, the representation of particulate matter in chemistry-transport models needs to be permanently evaluated and enhanced in order to refine our comprehension of PM pollution events and to propose consistent environmental policies. The study presented here focuses on two successive summer particulate pollution episodes that occurred on the French Mediterranean coast. We identify and analyze the constitutive elements of the first and more massive episode and we discuss their representation within a eulerian model.

    The results show that the model fails in reproducing the variability and the amplitude of dust import from western Africa, and that it constitutes a strong bias in PM daily forecasts. We then focus on the lack of diurnal variability in the model, which is attributed to missing urban sources in standard emission inventories, and notably the resuspension of particles by urban road traffic. Through a sensitivity study based on PM and NOx measurements, we assess the sensitivity of PM to local emissions and the need to reconsider road traffic PM sources. In parallel, by coupling the CHIMERE-DUST model outputs to our simulation, we show that the representation of transcontinental dust transport allows a much better representation of atmospheric particles in southern France, and that it is needed in the frame of air quality management for the quantification of the anthropogenic part of particulate matter pollution.

  14. Dust escape from Io

    Science.gov (United States)

    Flandes, Alberto

    2004-08-01

    The Dust ballerina skirt is a set of well defined streams composed of nanometric sized dust particles that escape from the Jovian system and may be accelerated up to >=200 km/s. The source of this dust is Jupiter's moon Io, the most volcanically active body in the Solar system. The escape of dust grains from Jupiter requires first the escape of these grains from Io. This work is basically devoted to explain this escape given that the driving of dust particles to great heights and later injection into the ionosphere of Io may give the particles an equilibrium potential that allow the magnetic field to accelerate them away from Io. The grain sizes obtained through this study match very well to the values required for the particles to escape from the Jovian system.

  15. Galactic dust properties

    Science.gov (United States)

    Paradis, D.

    2011-12-01

    Recent studies have shown evidence for variations in the dust emissivity law with temperature and wavelength. A recent dust emission model, called TLS model (for two-level systems), based on the description of the disordered internal structure of the amorphous dust grains has been developped to interpret observations in the far-infrared/submillimeter (FIR/submm) domain. A recent work focusing on the comparison between data of the diffuse interstellar medium seen by FIRAS-WMAP, as well as Archeops compact sources, with the TLS model allowed us to constrain the model parameters characterizing the general Galactic dust properties. Using the newly available Herschel/Hi-GAL data of the inner Galactic plane, we report a 500 μm emissivity excess in the peripheral parts of the Galactic plane, that can reach up to 20% of the emissivity. Results of the TLS modeling indicate significant changes in the dust properties from the central to peripheral parts of the Galactic plane.

  16. Determination of Geo-Environmental Factors and Source of Heavy Metals in Street Dust, Masjed-e- Soleiman City, Khouzestan Province

    Directory of Open Access Journals (Sweden)

    Z Javidaneh

    2016-09-01

    Full Text Available Background and Objectives: Street dust reflects one of the most important indicators of pollution in the urban environment. Most studies carried out in the world on heavy metal pollution are related to cities and metropolitans, while less attention has been paid to towns. Masjed-e- Soleiman, the most oil-rich town is located in the north eastern part of Khuzestan Province in Iran. This town contains geogenic pollutants such as gas and oil sources, oil and gas activities, oil and gas combustion, industries, and heavy traffic, which make it important from the viewpoint of environmental impact assessment. Materials and Methods: For monitoring and management of pollution, 11 samples of street dust were collected and prepared from different stations within the town during the dry season (June 2013. Each sample was analyzed using ICP-OES instrument. Results: Possible sources of the heavy metals were identified by multivariate analyses such as Principal Component Analysis (PCA and Cluster Analysis (CA. In addition, factors such as the Index of Geo-accumulation (Igeo, Pollution Index (PI, Integration Pollution Index (IPI, and Enrichment Factor (EF were assessed to determine the degree of heavy metals pollution in street dust of the Masjed-e- Soleiman Town. The results of PCA and CA indicated that the region is mostly affected by oil pollution (both natural and combustion of fossil fuels, traffic, and industrial activities (PI revealed high levels of Pb, Cd, Cu, and Zn pollution in samples and the average level of Ni, As, and V pollution in other samples. Igeo indicated the moderate to severe pollution of some samples to Pb, Cd, Cu, and Zn while no to moderate pollution against Ni, As, and V in other samples. EF for Pb, Cd, Cu, and Zn showed a significant pollution in some samples and other samples represented the least pollution against Ni, As, and V. Conclusion: Results showed that the concentrations of heavy metals in dust samples were higher than

  17. Synergistic Use of Remote Sensing and Modeling for Tracing Dust Storms in the Mediterranean

    Directory of Open Access Journals (Sweden)

    D. G. Kaskaoutis

    2012-01-01

    Full Text Available This study focuses on the detection of the dust source region and monitoring of the transport of the dust plume from its primary outflow to final deposition. The application area is the Sahara desert and the eastern Mediterranean, where two dust events occurred during the period 4–6 February 2009, an unusual event for a winter period. The Aqua-MODIS and OMI observations clearly define the spatial distribution of the dust plumes, while the CALIPSO observations of total attenuated backscatter (TAB at 532 nm, depolarization ratio (DR, and attenuated color ratio (1064/532 nm on 5 February 2009 provide a clear view and vertical structure of the dust-laden layer. The dust source region is defined to be near the Chad-Niger-Libyan borders, using satellite observations and model (DREAM output. This dust plume is vertically extended up to 2.5 km and is observed as a mass plume of dust from surface level to that altitude, where the vertical variation of TAB (0.002 to 0.2 and DR (0.2–0.5 implies dust-laden layer with non-spherical particles. CALIPSO profiles show that after the dust plume reached at its highest level, the dust particles start to be deposited over the Mediterranean and the initial dust plume was strongly attenuated, while features of dust were limited below about 1–1.5 km for latitudes northern of ~36° (Greek territory.

  18. 黄土高原黄土的成因:沙尘气溶胶源汇模拟与黄土堆积%The causes of loess formation over Loess Plateau:simulated dust aerosol sources and sinks and loess accumulation

    Institute of Scientific and Technical Information of China (English)

    刘唯佳; 韩永翔; 赵天良

    2014-01-01

    黄土高原是重要的降尘区还是沙尘源区这一科学问题至今未有确切定论.本文利用北半球气溶胶区域气候模式 NARCM,根据1995~2004年10a的模拟数据,分析了中国区域沙尘起沙量、沉降量以及沙尘的盈亏空间分布及风场,得到如下结论:1)沙漠及沙漠化地区是起沙量最大的区域、沉降量高值区集中在沙漠、沙漠化地区及其下风方向.黄土高原起沙量很小,而沉降量远大于起沙量.2)沙尘源区是沙漠及沙漠化地区,其余的地区则是沙尘汇区,降尘量由西北向东南递减.3)黄土高原因太行山和秦岭阻挡,处在最大的沙尘汇区.黄土高原的黄土是冰期和间冰期交替、经过漫长年代沙尘沉降的结果,模拟分析结论为黄土的风成学说提供了有力的证据.%There is a scientific debate argument whether Loess Plateau is an important region of dust aerosol sinks or sources. Based on the 10-year (1995~2004) aerosol simulations of the northern aerosol regional climate model NARCM, the spatial distribution of dust aerosol emissions, depositions and budgets as well as wind field were analyzed. The simulation analysis showed 1) the highest dust emissions appeared in the desert and desertification areas, while the highest dust depositions were concentrated over the desert and desertification areas as well as their immediately downwind region.The dust depositions largely exceeded the dust aerosol emission in Loess Plateau with the low dust emissions. 2) Desert and desertification area were the main dust sources, the rest of areas were dust sinks. Dust depositions declined from the northwest to the Southeast.3) Due to the barrier of the Taihang and Qinling Mountains, the Loess Plateau was the largest dust sink region with the highest depositions. The loess over Loess Plateau was accumulated by dust depositions over the long term evolution of glacial and interglacial periods. The dust aerosol simulation provided a solid

  19. Spatial control of processing plasmas in a multicusp plasma source equipped with a movable magnetic filter

    Energy Technology Data Exchange (ETDEWEB)

    Fukumasa, O.; Naitou, H.; Sakiyama, S. (Yamaguchi Univ., Yamaguchi (Japan))

    1991-12-20

    The plasma chemical vapor deposition (p-CVD) method has been used in the preparation of various sorts of thin films such as hydrogenated amorphous silicon films and hydrogenated amorphous carbon films, etc. and the application feasibility of a magnetically filtered multicusp plasma source has been studied. In this paper, it is confirmed that plasma parameters (H {sub 2} - ch {sub 4} or Ar-CH {sub 4} plasmas) are spatially well controlled by using both a movable magnetic filter and a plasma grid. Plasma parameters change sharply across the magnetic filter at any filter position and the whole plasma is divided clearly into the region of source plasma with high-energy electrons and the region of diffused plasma without high-energy electrons. Concerning the role of the magnetic filter which reflects preferentially high-energy electrons, a study is made through computer simulation. 7 refs., 9 figs.

  20. Spatially resolved optical-emission spectroscopy of a radio-frequency driven iodine plasma source

    Science.gov (United States)

    Dedrick, James; Doyle, Scott; Grondein, Pascaline; Aanesland, Ane

    2016-09-01

    Iodine is of interest for potential use as a propellant for spacecraft propulsion, and has become attractive as a replacement to xenon due to its similar mass and ionisation potential. Optical emission spectroscopy has been undertaken to characterise the emission from a low-pressure, radio-frequency driven inductively coupled plasma source operating in iodine with respect to axial distance across its transverse magnetic filter. The results are compared with axial profiles of the electron temperature and density for identical source conditions, and the spatial distribution of the emission intensity is observed to be closely correlated with the electron temperature. This work has been done within the LABEX Plas@Par project, and received financial state aid managed by the ``Agence Nationale de la Recherche'', as part of the ``Programme d'Investissements d'Avenir'' under the reference ANR-11-IDEX-0004-02.

  1. MISR Decadal Observations of Mineral Dust: Property Characterization and Climate Applications

    Science.gov (United States)

    Kalashnikova, Olga V.; Garay, Michael J.; Sokolik, Irina; Kahn, Ralph A.; Lyapustin, A.; Diner, David J.; Lee, Jae N.; Torres, Omar; Leptoukh, Gregory G.; Sabbah, Ismail

    2012-01-01

    The Multi-angle Imaging SpectroRadiometer (MISR) provides a unique, independent source of data for studying dust emission and transport. MISR's multiple view angles allow the retrieval of aerosol properties over bright surfaces, and such retrievals have been shown to be sensitive to the non-sphericity of dust aerosols over both land and water. MISR stereographic views of thick aerosol plumes allow height and instantaneous wind derivations at spatial resolutions of better than 1.1 km horizontally and 200m vertically. We will discuss the radiometric and stereo-retrieval capabilities of MISR specifically for dust, and demonstrate the use of MISR data in conjunction with other available satellite observations for dust property characterization and climate studies.First, we will discuss MISR non-spherical (dust) fraction product over the global oceans. We will show that over the Atlantic Ocean, changes in the MISR-derived non-spherical AOD fraction illustrate the evolution of dust during transport. Next, we will present a MISR satellite perspective on dust climatology in major dust source regions with a particular emphasis on the West Africa and Middle East and discuss MISR's unique strengths as well as current product biases. Finally, we will discuss MISR dust plume product and climatological applications.

  2. The dust properties of the Beta Pictoris disk

    Science.gov (United States)

    Augereau, J.-C.

    2014-09-01

    The dust grains in orbit around Beta Pictoris are an essential source of information about its planetary system. Their spatial distribution and properties tell us about the dynamics and composition of their parent, km-sized bodies, and how they interact with the planet(s). Since its discovery, thirty years ago, the Beta Pictoris disk has been intensively observed with a wealth of technics that probed the dust grains at different spatial scales and different wavelengths: broad-band photometry, (infrared) spectroscopy, scattered light and thermal emission direct imaging, polarimetry, optical and millimeter interferometry... In this talk, I will try to take stock of the knowledge accumulated over the last thirty years on dust in the planetary system of Beta Pictoris. Specific emphasis will be placed on the numerous remaining uncertainties.

  3. Farmer data sourcing. The case study of the spatial soil information maps in South Tyrol.

    Science.gov (United States)

    Della Chiesa, Stefano; Niedrist, Georg; Thalheimer, Martin; Hafner, Hansjörg; La Cecilia, Daniele

    2017-04-01

    Nord-Italian region South Tyrol is Europe's largest apple growing area exporting ca. 15% in Europe and 2% worldwide. Vineyards represent ca. 1% of Italian production. In order to deliver high quality food, most of the farmers in South Tyrol follow sustainable farming practices. One of the key practice is the sustainable soil management, where farmers collect regularly (each 5 years) soil samples and send for analyses to improve cultivation management, yield and finally profitability. However, such data generally remain inaccessible. On this regard, in South Tyrol, private interests and the public administration have established a long tradition of collaboration with the local farming industry. This has granted to the collection of large spatial and temporal database of soil analyses along all the cultivated areas. Thanks to this best practice, information on soil properties are centralized and geocoded. The large dataset consist mainly in soil information of texture, humus content, pH and microelements availability such as, K, Mg, Bor, Mn, Cu Zn. This data was finally spatialized by mean of geostatistical methods and several high-resolution digital maps were created. In this contribution, we present the best practice where farmers data source soil information in South Tyrol. Show the capability of a large spatial-temporal geocoded soil dataset to reproduce detailed digital soil property maps and to assess long-term changes in soil properties. Finally, implication and potential application are discussed.

  4. Estimation of Dust Emission from the Western Coastal Plains of Arabian Peninsula

    Science.gov (United States)

    Anisimov, Anatolii; Stenchikov, Georgiy

    2016-04-01

    This study is aimed at quantifying local-scale dust emission from the coastal areas of western Arabian Peninsula. The dust emitted from these areas is frequently deposited directly to the Red Sea, acting as an important component of the nutrient balance of marine ecosystems. Most chemicals including iron, phosphorus, and nitrogen are introduced to the Red Sea with airborne dust. This process is especially significant for the oligotrophic northern Red Sea, where nutrients from the Indian Ocean cannot reach and the nutrient supply from land river discharge is negligible. The dust deposition to the Red Sea associated with major dust storms was recently estimated to be about 6 Tg/yr, but this estimate does not account for local, small-scale dust outbreaks occurring during fair weather conditions or moderate winds. The seasonality and the magnitude of this nutrient supply are largely unknown. In the present study, we quantify dust emissions using the fine-scale off-line version-4 of the Community Land Model (CLM4) with the high-resolution datasets as input parameters. We examine the model sensitivity to the spatial resolution of input land cover and vegetation data, and compare the results with weather station observations and reanalysis to choose the best model configuration. The model results are shown to be in reasonable agreement with station visibility measurements and the frequency of dust event reports. To improve the spatial characteristics of dust emission, we apply two state-of-the-art dust source functions. We found that the source function based on measurements from SEVIRI satellite substantially improves the simulation results, being in good agreement with both reanalysis data and station measurements. We identify the major dust source hot-spot areas over the coastal plain and analyze the seasonal and diurnal variability of dust emissions. The annual dust generation from the 145000 km2 coastal area reaches 6 Tg/yr. Roughly half of emitted dust could be

  5. A Spatially Resolved Study of Cold Dust, Molecular Gas, H ii Regions, and Stars in the z = 2.12 Submillimeter Galaxy ALESS67.1

    Science.gov (United States)

    Chen, Chian-Chou; Hodge, J. A.; Smail, Ian; Swinbank, A. M.; Walter, Fabian; Simpson, J. M.; Calistro Rivera, Gabriela; Bertoldi, F.; Brandt, W. N.; Chapman, S. C.; da Cunha, Elisabete; Dannerbauer, H.; De Breuck, C.; Harrison, C. M.; Ivison, R. J.; Karim, A.; Knudsen, K. K.; Wardlow, J. L.; Weiß, A.; van der Werf, P. P.

    2017-09-01

    We present detailed studies of a z = 2.12 submillimeter galaxy, ALESS67.1, using sub-arcsecond resolution ALMA, adaptive optics-aided VLT/SINFONI, and Hubble Space Telescope (HST)/CANDELS data to investigate the kinematics and spatial distributions of dust emission (870 μm continuum), 12CO(J = 3–2), strong optical emission lines, and visible stars. Dynamical modeling of the optical emission lines suggests that ALESS67.1 is not a pure rotating disk but a merger, consistent with the apparent tidal features revealed in the HST imaging. Our sub-arcsecond resolution data set allows us to measure half-light radii for all the tracers, and we find a factor of 4–6 smaller sizes in dust continuum compared to all the other tracers, including 12CO; also, ultraviolet (UV) and Hα emission are significantly offset from the dust continuum. The spatial mismatch between the UV continuum and the cold dust and gas reservoir supports the explanation that geometrical effects are responsible for the offset of the dusty galaxy on the IRX–β diagram. Using a dynamical method we derive an {α }{CO}=1.8+/- 1.0, consistent with other submillimeter galaxies (SMGs) that also have resolved CO and dust measurements. Assuming a single {α }{CO} value we also derive resolved gas and star formation rate surface densities, and find that the core region of the galaxy (≲ 5 kpc) follows the trend of mergers on the Schmidt–Kennicutt relationship, whereas the outskirts (≳ 5 kpc) lie on the locus of normal star-forming galaxies, suggesting different star formation efficiencies within one galaxy. Our results caution against using single size or morphology for different tracers of the star formation activity and gas content of galaxies, and therefore argue the need to use spatially resolved, multi-wavelength observations to interpret the properties of SMGs, and perhaps even for z> 1 galaxies in general.

  6. SPITZER IRS SPECTRAL MAPPING OF THE TOOMRE SEQUENCE: SPATIAL VARIATIONS OF PAH, GAS, AND DUST PROPERTIES IN NEARBY MAJOR MERGERS

    Energy Technology Data Exchange (ETDEWEB)

    Haan, S.; Armus, L.; Laine, S.; Surace, J. A.; Diaz-Santos, T.; Beirao, P.; Stierwalt, S. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Smith, J. D. [Ritter Astrophysical Observatory, University of Toledo, Toledo, OH 43606 (United States); Schweizer, F.; Murphy, E. J. [Observatories of the Carnegie Institution, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Brandl, B. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Evans, A. S.; Hibbard, J. E. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Yun, M. [Astronomy Department, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Jarrett, T. H. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2011-12-01

    We have mapped the key mid-IR diagnostics in eight major merger systems of the Toomre sequence (NGC 4676, NGC 7592, NGC 6621, NGC 2623, NGC 6240, NGC 520, NGC 3921, and NGC 7252) using the Spitzer Infrared Spectrograph. With these maps, we explore the variation of the ionized-gas, polycyclic aromatic hydrocarbon (PAH), and warm gas (H{sub 2}) properties across the sequence and within the galaxies. While the global PAH interband strength and ionized gas flux ratios ([Ne III]/[Ne II]) are similar to those of normal star-forming galaxies, the distribution of the spatially resolved PAH and fine structure line flux ratios is significantly different from one system to the other. Rather than a constant H{sub 2}/PAH flux ratio, we find that the relation between the H{sub 2} and PAH fluxes is characterized by a power law with a roughly constant exponent (0.61 {+-} 0.05) over all merger components and spatial scales. While following the same power law on local scales, three galaxies have a factor of 10 larger integrated (i.e., global) H{sub 2}/PAH flux ratio than the rest of the sample, even larger than what it is in most nearby active galactic nuclei. These findings suggest a common dominant excitation mechanism for H{sub 2} emission over a large range of global H{sub 2}/PAH flux ratios in major mergers. Early-merger systems show a different distribution between the cold (CO J = 1-0) and warm (H{sub 2}) molecular gas components, which is likely due to the merger interaction. Strong evidence for buried star formation in the overlap region of the merging galaxies is found in two merger systems (NGC 6621 and NGC 7592) as seen in the PAH, [Ne II], [Ne III], and warm gas line emission, but with no apparent corresponding CO (J = 1-0) emission. The minimum of the 11.3/7.7 {mu}m PAH interband strength ratio is typically located in the nuclei of galaxies, while the [Ne III/[Ne II] ratio increases with distance from the nucleus. Our findings also demonstrate that the variations of

  7. A Bright Spatially-Coherent Compact X-ray Synchrotron Source

    CERN Document Server

    Kneip, S; Martins, J L; Martins, S F; Bellei, C; Chvykov, V; Dollar, F; Fonseca, R; Huntington, C; Kalintchenko, G; Maksimchuk, A; Mangles, S P D; Matsuoka, T; Nagel, S R; Palmer, C; Schreiber, J; Phuoc, K Ta; Thomas, A G R; Yanovsky, V; Silva, L O; Krushelnick, K; Najmudin, Z

    2009-01-01

    Each successive generation of x-ray machines has opened up new frontiers in science, such as the first radiographs and the determination of the structure of DNA. State-of-the-art x-ray sources can now produce coherent high brightness keV x-rays and promise a new revolution in imaging complex systems on nanometre and femtosecond scales. Despite the demand, only a few dedicated synchrotron facilities exist worldwide, partially due the size and cost of conventional (accelerator) technology. Here we demonstrate the use of a recently developed compact laser-plasma accelerator to produce a well-collimated, spatially-coherent, intrinsically ultrafast source of hard x-rays. This method reduces the size of the synchrotron source from the tens of metres to centimetre scale, accelerating and wiggling a high electron charge simultaneously. This leads to a narrow-energy spread electron beam and x-ray source that is >1000 times brighter than previously reported plasma wiggler and thus has the potential to facilitate a myri...

  8. Sources, sinks, and spatial ecology of cotton mice in longleaf pine stands undergoing restoration

    Science.gov (United States)

    Sharp, N.W.; Mitchell, M.S.; Grand, J.B.

    2009-01-01

    The Fire and Fire Surrogate studya replicated, manipulative experimentsought the most economically and ecologically efficient way to restore the nation's fire-maintained ecosystems. As part of this study, we conducted a 3-year markrecapture study, comprising 105,000 trap-nights, to assess demographic responses of cotton mice (Peromyscus gossypinus) to Fire and Fire Surrogate treatments at the Gulf Coastal Plain site, where longleaf pine was the ecosystem to be restored. We compared competing models to evaluate restoration effects on variation in apparent survival and recruitment over time, space, and treatment, and incorporated measures of available source habitat for cotton mice with reverse-time modeling to infer immigration from outside the study area. The top-ranked survival model contained only variation over time, but the closely ranked 2nd and 3rd models included variation over space and treatment, respectively. The top 4 recruitment models all included effects for availability of source habitat and treatments. Burning appeared to degrade habitat quality for cotton mice, showing demographic characteristics of a sink, but treatments combining fire with thinning of trees or application of herbicide to the understory appeared to improve habitat quality, possibly creating sources. Bottomland hardwoods outside the study also acted as sources by providing immigrants to experimental units. Models suggested that population dynamics operated over multiple spatial scales. Treatments applied to 15-ha stands probably only caused local variation in vital rates within the larger population. ?? 2009 American Society of Mammalogists.

  9. Analysis of spatial variations and sources of heavy metals in farmland soils of Beijing suburbs.

    Directory of Open Access Journals (Sweden)

    Jianmei Zou

    Full Text Available To understand the effect of intense human activities in suburbs on environmental quality, we obtained 758 measurements of the heavy metals in certain farmland soils of the Beijing suburbs. Multivariate statistical analysis and geostatistical analysis were used to conduct a basic analysis of the heavy metal concentrations, the distribution characteristics and the sources of pollution of the farmland soils in these suburbs. The results showed the presence of eight heavy metals in the agricultural soils at levels exceeding the background values for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. In particular, all the measured Cr concentrations exceeded the background value, while As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were present at 1.13, 1.68, 1.95, 1.43, 1.63, 0.79, 0.92 and 1.36 times their background values, respectively. The results of correlation, factor and spatial structure analyses showed that Cd, Cu, Pb and Zn were strongly homologous, whereas Cr and Hg showed a degree of heterogeneity. The analysis further indicated that in addition to natural factors, Cd, Cu, Pb and Zn in the soil were mainly associated with distribution from road traffic and land use status. Different agricultural production measures in the various areas were also important factors that affected the spatial distribution of the soil Cr concentration. The major sources of Hg pollution were landfills for industrial waste and urban domestic garbage, while the spatial distribution of As was more likely to be a result of composite pollution. The regional distribution of the heavy metals indicated that except for Cr and Hg, the high heavy metal levels occurred in districts and counties with higher organic matter concentrations, such as the northwestern and southeastern suburbs of Beijing. There was no significant Ni pollution in the agricultural soils of the Beijing suburbs.

  10. Investigation of outdoor BTEX: Concentration, variations, sources, spatial distribution, and risk assessment.

    Science.gov (United States)

    Miri, Mohammad; Rostami Aghdam Shendi, Maryam; Ghaffari, Hamid Reza; Ebrahimi Aval, Hamideh; Ahmadi, Ehsan; Taban, Ebrahim; Gholizadeh, Abdolmajid; Yazdani Aval, Mohsen; Mohammadi, Amir; Azari, Ali

    2016-11-01

    The aim of this study was to measure BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations in the ambient air of Tehran, the capital of Iran, and investigate their seasonal variations, probable sources, spatial mapping, and risk assessment. The concentrations of BTEX were measured using a continuous monitoring device installed in seven stations around the city. Spatial mapping procedure was conducted using the inverse distance weighting (IDW) method. Monte Carlo simulation was used to assess the carcinogenic and noncarcinogenic risks imposed by BTEX. The highest and lowest annual mean concentrations of toluene and ethylbenzene were recorded as 16.25 and 3.63 μg m(-3), respectively. The maximum (6.434) and minimum (3.209) toluene/benzene (T/B) ratio was observed in summer and winter, respectively. The spatial distribution of BTEX pollution indicated that the highest concentrations were found along the major roads because of heavy traffic. Spearman's rank correlation coefficients and concentration ratios showed that BTEX were produced by the multiemission sources. The mean of inhalation lifetime cancer risk (LTCR) for benzene was 3.93 × 10(-7), which is lower than the limits recommended by the United States Environmental Protection Agency (US EPA) and the World Health Organization (WHO). The hazard quotient (HQ), noncarcinogenic risk index, for all BTEX compounds was <1. The obtained results showed no threat of BTEX concentrations to human health. However, as the concentrations of BTEX will increase due to the rapid growth of vehicles and industrial activities, much effort is required to control and manage the levels of these compounds in the future. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Mobile measurements of ammonia: Sources and spatial variations in the Wallis region and Zurich (Switzerland)

    Science.gov (United States)

    Elser, Miriam; El Haddad, Imad; Bruns, Emily; Pieber, Simone; Wolf, Robert; Krishna Kumar, Nivedita; Prévôt, André; Baltensperger, Urs

    2014-05-01

    Ammonia (NH3) has negative impacts on human health, climate, ecosystems and materials. Moreover, it is also an important precursor for the formation of secondary aerosols in the form of ammonium salts (ammonium nitrate, ammonium sulfate and ammonium chloride). Previous studies have shown that the vast majority of the ammonia emissions come from the agricultural sector (mostly from livestock farming and fertilizing activities). Other sources such as road transport, waste deposit, energy use and supply can also contribute to the ammonia levels in the urban areas. High concentrations of ammonia are commonly measured at the National Air Pollution Monitoring Network (NABEL) stations in Switzerland. Mobile measurements of ammonia and other pollutants (including BC, CO2, NOx and NR-PM) were conducted in the Wallis region and in Zurich in 2013 to study the spatial distribution of ammonia in Switzerland and identify its major emission sources in these regions. A new heated inlet setup was developed to improve the response time of the ammonia measurements, so that even very local sources could be identified. For both, the Wallis region and Zurich, it was observed that the background values of ammonia have a regional origin, as other pollutants affected by regional changes show similar background trends. These regional background values varied between 5 to 10 ppb during the different days of measurements. Moreover, no big differences were observed in the background values between the city center, the surrounding areas, the highway and the rural areas. The major local source of ammonia observed during these measurements was road transport, producing increases on the NH3 levels up to 4 times the background values. Based on emission factors estimated from tunnel measurements, the traffic was estimated to contribute between 20 -30% of the measured ammonia levels on a daily average in Zurich. Other sources of ammonia that can also contribute significantly to the levels of ammonia

  12. Uncertainty in modeling dust mass balance and radiative forcing from size parameterization

    Directory of Open Access Journals (Sweden)

    C. Zhao

    2013-07-01

    Full Text Available This study examines the uncertainties in simulating mass balance and radiative forcing of mineral dust due to biases in the dust size parameterization. Simulations are conducted quasi-globally (180° W–180° E and 60° S–70° N using the WRF-Chem model with three different approaches to represent dust size distribution (8-bin, 4-bin, and 3-mode. The biases in the 3-mode or 4-bin approaches against a relatively more accurate 8-bin approach in simulating dust mass balance and radiative forcing are identified. Compared to the 8-bin approach, the 4-bin approach simulates similar but coarser size distributions of dust particles in the atmosphere, while the 3-mode approach retains more fine dust particles but fewer coarse dust particles due to its prescribed σg of each mode. Although the 3-mode approach yields up to 10 days longer dust mass lifetime over the remote oceanic regions than the 8-bin approach, the three size approaches produce similar dust mass lifetime (3.2 days to 3.5 days on quasi-global average, reflecting that the global dust mass lifetime is mainly determined by the dust mass lifetime near the dust source regions. With the same global dust emission (∼6000 Tg yr-1, the 8-bin approach produces a dust mass loading of 39 Tg, while the 4-bin and 3-mode approaches produce 3% (40.2 Tg and 25% (49.1 Tg higher dust mass loading, respectively. The difference in dust mass loading between the 8-bin approach and the 4-bin or 3-mode approaches has large spatial variations, with generally smaller relative difference (-2 and atmospheric warming (0.39∼0.96 W m-2 and in a tremendous difference of a factor of ∼10 in dust TOA cooling (-0.24∼-2.20 W m-2. An uncertainty of a factor of 2 is quantified in dust emission estimation due to the different size parameterizations. This study also highlights the uncertainties in modeling dust mass and number loading, deposition fluxes, and radiative forcing resulting from different size

  13. Isotopic signatures suggest important contributions from recycled gasoline, road dust and non-exhaust traffic sources for copper, zinc and lead in PM10 in London, United Kingdom

    Science.gov (United States)

    Dong, Shuofei; Ochoa Gonzalez, Raquel; Harrison, Roy M.; Green, David; North, Robin; Fowler, Geoff; Weiss, Dominik

    2017-09-01

    The aim of this study was to improve our understanding of what controls the isotope composition of Cu, Zn and Pb in particulate matter (PM) in the urban environment and to develop these isotope systems as possible source tracers. To this end, isotope ratios (Cu, Zn and Pb) and trace element concentrations (Fe, Al, Cu, Zn, Sb, Ba, Pb, Cr, Ni and V) were determined in PM10 collected at two road sites with contrasting traffic densities in central London, UK, during two weeks in summer 2010, and in potential sources, including non-combustion traffic emissions (tires and brakes), road furniture (road paint, manhole cover and road tarmac surface) and road dust. Iron, Ba and Sb were used as proxies for emissions derived from brake pads, and Ni, and V for emissions derived from fossil fuel oil. The isotopic composition of Pb (expressed using 206Pb/207Pb) ranged between 1.1137 and 1.1364. The isotope ratios of Cu and Zn expressed as δ65CuNIST976 and δ66ZnLyon ranged between -0.01‰ and +0.51‰ and between -0.21‰ and +0.33‰, respectively. We did not find significant differences in the isotope signatures in PM10 over the two weeks sampling period and between the two sites, suggesting similar sources for each metal at both sites despite their different traffic densities. The stable isotope composition of Pb suggests significant contribution from road dust resuspension and from recycled leaded gasoline. The Cu and Zn isotope signatures of tires, brakes and road dust overlap with those of PM10. The correlation between the enrichments of Sb, Cu, Ba and Fe in PM10 support the previously established hypothesis that Cu isotope ratios are controlled by non-exhaust traffic emission sources in urban environments (Ochoa Gonzalez et al., 2016). Analysis of the Zn isotope signatures in PM10 and possible sources at the two sites suggests significant contribution from tire wear. However, temporary additional sources, likely high temperature industrial emissions, need to be invoked

  14. Discernible rhythm in the spatio/temporal distributions of transatlantic dust

    Directory of Open Access Journals (Sweden)

    Y. Ben-Ami

    2011-08-01

    −1, and 1300 km in total. These rates of northward advance and southern retreat of the dust transport route are in accordance with the simultaneous shift of the Inter Tropical Front.

    Based on cross-correlation analyses, we attribute the observed rhythm to the contrast between the northwestern and southern Saharan dust source spatial distributions. Despite the vast difference in areas, the Bodélé Depression, located in Chad, appears to modulate transatlantic dust patterns about half the time. The proposed partition captures the essence of transatlantic dust climatology and may, therefore, supply a natural temporal framework for dust analysis via models and observations.

  15. Global sand and dust storms in 2008: Observation and HYSPLIT model verification

    Science.gov (United States)

    Wang, Yaqiang; Stein, Ariel F.; Draxler, Roland R.; de la Rosa, Jesús D.; Zhang, Xiaoye

    2011-11-01

    The HYSPLIT model has been applied to simulate the global dust distribution for 2008 using two different dust emission schemes. The first one assumes that emissions could occur from any land-use grid cell defined in the model as desert. The second emission approach uses an empirically derived algorithm based on satellite observations. To investigate the dust storm features and verify the model performance, a global dataset of Integrated Surface Hourly (ISH) observations has been analyzed to map the spatial distribution and seasonal variation of sand and dust storms. Furthermore, the PM 10 concentration data at four stations in Northern China and two stations in Southern Spain, and the AOD data from a station located at the center of the Sahara Desert have been compared with the model results. The spatial distribution of observed dust storm frequency from ISH shows the known high frequency areas located in North Africa, the Middle East, Mongolia and Northwestern China. Some sand and dust storms have also been observed in Australia, Mexico, Argentina, and other sites in South America. Most of the dust events in East Asia occur in the spring, however this seasonal feature is not so evident in other dust source regions. In general, the model reproduces the dust storm frequency for most of the regions for the two emission approaches. Also, a good quantitative performance is achieved at the ground stations in Southern Spain and Western China when using the desert land-use based emissions, although HYSPLIT overestimates the dust concentration at downwind areas of East Asia and underestimates the column in the center of the Saharan Desert. On the other hand, the satellite based emission approach improves the dust forecast performance in the Sahara, but underestimates the dust concentrations in East Asia.

  16. PCB-containing wood floor finish is a likely source of elevated PCBs in residents' blood, household air and dust: a case study of exposure.

    Science.gov (United States)

    Rudel, Ruthann A; Seryak, Liesel M; Brody, Julia G

    2008-01-17

    Polychlorinated biphenyls (PCBs) are persistent pollutants identified worldwide as human blood and breast milk contaminants. Because they bioaccumulate, consumption of meat, fish, and dairy products predicts human blood concentrations. PCBs were also used widely in building materials, including caulks and paints, but few studies have evaluated the contribution of these exposures to body burden. In an earlier study, we detected PCBs in indoor air in 31% of 120 homes on Cape Cod, MA. Two of the homes had much higher concentrations than the rest, so we retested to verify the initial finding, evaluate blood PCB concentrations of residents, and identify the PCB source. Air and dust concentrations remained elevated over 5 years between initial and follow-up sampling. Blood serum concentrations of PCBs in residents of the homes were generally elevated above the 95th percentile of a representative sample of the US population. Serum concentrations in residents and air and dust concentrations were especially high in a home where a resident reported use of PCB-containing floor finish in the past, and where the floor of one room was sanded and refinished just prior to sample collection. This case-study suggests that PCB residues in homes may be more significant contributors to overall exposure than diet for some people, and that use of a commercially-available PCB-containing wood floor finish in residences during the 1950s and 1960s is an overlooked but potentially important source of current PCB exposure in the general population.

  17. Pan-European modelling of riverine nutrient concentrations - spatial patterns, source detection, trend analyses, scenario modelling

    Science.gov (United States)

    Bartosova, Alena; Arheimer, Berit; Capell, Rene; Donnelly, Chantal; Strömqvist, Johan

    2016-04-01

    Nutrient transport models are important tools for large scale assessments of macro-nutrient fluxes (nitrogen, phosphorus) and thus can serve as support tool for environmental assessment and management. Results from model applications over large areas, i.e. from major river basin to continental scales can fill a gap where monitoring data is not available. Here, we present results from the pan-European rainfall-runoff and nutrient transfer model E-HYPE, which is based on open data sources. We investigate the ability of the E-HYPE model to replicate the spatial and temporal variations found in observed time-series of riverine N and P concentrations, and illustrate the model usefulness for nutrient source detection, trend analyses, and scenario modelling. The results show spatial patterns in N concentration in rivers across Europe which can be used to further our understanding of nutrient issues across the European continent. E-HYPE results show hot spots with highest concentrations of total nitrogen in Western Europe along the North Sea coast. Source apportionment was performed to rank sources of nutrient inflow from land to sea along the European coast. An integrated dynamic model as E-HYPE also allows us to investigate impacts of climate change and measure programs, which was illustrated in a couple of scenarios for the Baltic Sea. Comparing model results with observations shows large uncertainty in many of the data sets and the assumptions used in the model set-up, e.g. point source release estimates. However, evaluation of model performance at a number of measurement sites in Europe shows that mean N concentration levels are generally well simulated. P levels are less well predicted which is expected as the variability of P concentrations in both time and space is higher. Comparing model performance with model set-ups using local data for the Weaver River (UK) did not result in systematically better model performance which highlights the complexity of model

  18. Investigation of Three-Dimensional Evolution of East Asian Dust Storm by Modeling and Remote Sensing Measurements

    Directory of Open Access Journals (Sweden)

    Jiawei Li

    2015-01-01

    Full Text Available The three-dimensional evolution of an East Asian dust storm during 23–26 April 2009 was investigated by utilizing a regional air quality model system (RAQMS and satellite measurements. This severe dust storm hit Mt. Tai in east China with daily mean PM10 concentration reaching 1400 μg/m3 and the model captured the PM10 variation reasonably well. Modeled spatial distributions of AOD and vertical profiles of aerosol extinction coefficient during the dust storm were compared with MODIS and CALIPSO data, demonstrating that RAQMS was able to reproduce the 3D structure and the evolution of the dust storm reasonably well. During early days of the dust storm, daily mean dust-induced AOD exceeded 2.0 over dust source regions (the Gobi desert and the Taklamakan desert and was in a range of 1.2–1.8 over the North China Plain, accounting for about 98% and up to 90% of total AOD over corresponding areas, respectively. The top of the dust storm reached about 8 km over east China, with high dust concentration locating at around 40°N. Dust aerosol below 2 km was transported southeastward off the Gobi desert while dust above 2 km was transported out of China along 40°–45°N.

  19. Optical Estimation on Pollution Level of Respirable Dust Based on Infrared Transmitting Behavior in Coalmine Fully Mechanized Working Face

    Directory of Open Access Journals (Sweden)

    Wen-Zheng Wang

    2016-01-01

    Full Text Available Respirable coal particle generated during underground mining is the main cause for gas-dust explosions and coal workers’ pneumoconiosis (CWP which needs accurate monitoring especially on its concentration. Focusing on the coal dust pollution in the fully mechanized working face of Huangbaici coalmine, coal particle was sampled for further industrial analysis and FT-IR test to obtain its chemical composition and optical constant. Combined with the simulated spatial distribution of airborne dust, the spectral transmission characteristics of coal dust within wavelengths of 2.5 to 25 μm under different operating conditions were obtained. The simulation results show that the transmittance and aerosol optical depth (AOD of coal dust are closely linked and obviously influenced by the variation of dust generation source (intensity of dust release, position of coal cutting, and the wetting of the coal seam and airflow field (wind speed and direction of ventilation. Furthermore, an optical channel of 1260–1280 cm−1 (7.937–7.813 μm which is almost only sensitive to the variation of dust concentration but dull to the diameter change of coal dust was selected to establish the correlation of dust concentration and infrared transmittance. The fitting curve was then applied to retrieve the equivalent dust concentration based on optical information, and the comparison results demonstrate that the estimated pollution level is consistent with field measurement data in engineering practice.

  20. Spatial and Temporal Variations of Light Curves in Gravitationally Lensed Sources

    CERN Document Server

    Minakov, A A

    2004-01-01

    Effects of macro-and microlensing on the spatial and temporal characteristics of images of remote sources, observed through the inner regions of lensing galaxies are discussed. A particular attention was given to the case, when microlenses, - stars, star-like or planetary bodies, - are situated near the critical curves of macrolenses, - galaxies, stellar clusters, etc. The investigation is of interest for the gravitational lens (GL) systems, where the lensed images are observed close to the critical curve of a macrolens. Annular, arched or confluent images should be regarded as an indication to such a proximity. Numerical simulation allowed to determine the structure of critical curves and caustics, formed by macro and microlenses, and to evaluate possible distortions, caused by microlenses for various locations with respect to the critical curve of a regular lens. The difference of our results from those obtained earlier with the standard (linearized) approach to describe the regular gravitational lens was s...

  1. Localization of Narrow-Band Sources in Unknown Spatially Correlated Noise

    Directory of Open Access Journals (Sweden)

    Salah Bourennane

    2010-01-01

    Full Text Available In subspace-based method for direction-of-arrival (DOA estimation of signal wavefronts, the additive noise term is often assumed to be spatially white or known to within a multiplicative scalar. When the noise is nonwhite but has a known covariance matrix, we can still handle the problem through prewhitening. However, the problem turns to be complex when the noise field is completely unknown. In this paper, we study the localization of the sources, when the noise covariance matrix is one unknown band matrix. An iterative denoising algorithm based on the noise subspace spanned by the eigenvectors associated with the smallest eigenvalues is developed. The performance of the proposed algorithm is evaluated by computer simulations. We also test the proposed algorithm with some experimental data recorded during an underwater acoustic experiment.

  2. Developing an open source-based spatial data infrastructure for integrated monitoring of mining areas

    Science.gov (United States)

    Lahn, Florian; Knoth, Christian; Prinz, Torsten; Pebesma, Edzer

    2014-05-01

    In all phases of mining campaigns, comprehensive spatial information is an essential requirement in order to ensure economically efficient but also safe mining activities as well as to reduce environmental impacts. Earth observation data acquired from various sources like remote sensing or ground measurements is important e.g. for the exploration of mineral deposits, the monitoring of mining induced impacts on vegetation or the detection of ground subsidence. The GMES4Mining project aims at exploring new remote sensing techniques and developing analysis methods on various types of sensor data to provide comprehensive spatial information during mining campaigns (BENECKE et al. 2013). One important task in this project is the integration of the data gathered (e.g. hyperspectral images, spaceborne radar data and ground measurements) as well as results of the developed analysis methods within a web-accessible data source based on open source software. The main challenges here are to provide various types and formats of data from different sensors and to enable access to analysis and processing techniques without particular software or licensing requirements for users. Furthermore the high volume of the involved data (especially hyperspectral remote sensing images) makes data transfer a major issue in this use case. To engage these problems a spatial data infrastructure (SDI) including a web portal as user frontend is being developed which allows users to access not only the data but also several analysis methods. The Geoserver software is used for publishing the data, which is then accessed and visualized in a JavaScript-based web portal. In order to perform descriptive statistics and some straightforward image processing techniques on the raster data (e.g. band arithmetic or principal component analysis) the statistics software R is implemented on a server and connected via Rserve. The analysis is controlled and executed directly by the user through the web portal and

  3. Spatial Distribution, Sources Apportionment and Health Risk of Metals in Topsoil in Beijing, China.

    Science.gov (United States)

    Sun, Chunyuan; Zhao, Wenji; Zhang, Qianzhong; Yu, Xue; Zheng, Xiaoxia; Zhao, Jiayin; Lv, Ming

    2016-07-20

    In order to acquire the pollution feature and regularities of distribution of metals in the topsoil within the sixth ring road in Beijing, a total of 46 soil samples were collected, and the concentrations of twelve elements (Nickel, Ni, Lithium, Li, Vanadium, V, Cobalt, Co, Barium, Ba, Strontium, Sr, Chrome, Cr, Molybdenum, Mo, Copper, Cu, Cadmium, Cd, Zinc, Zn, Lead, Pb) were analyzed. Geostatistics and multivariate statistics were conducted to identify spatial distribution characteristics and sources. In addition, the health risk of the analyzed heavy metals to humans (adult) was evaluated by an U.S. Environmental Protection Agency health risk assessment model. The results indicate that these metals have notable variation in spatial scale. The concentration of Cr was high in the west and low in the east, while that of Mo was high in the north and low in the south. High concentrations of Cu, Cd, Zn, and Pb were found in the central part of the city. The average enrichment degree of Cd is 5.94, reaching the standard of significant enrichment. The accumulation of Cr, Mo, Cu, Cd, Zn, and Pb is influenced by anthropogenic activity, including vehicle exhaustion, coal burning, and industrial processes. Health risk assessment shows that both non-carcinogenic and carcinogenic risks of selected heavy metals are within the safety standard and the rank of the carcinogenic risk of the four heavy metals is Cr > Co > Ni > Cd.

  4. Spatial Distribution, Sources Apportionment and Health Risk of Metals in Topsoil in Beijing, China

    Directory of Open Access Journals (Sweden)

    Chunyuan Sun

    2016-07-01

    Full Text Available In order to acquire the pollution feature and regularities of distribution of metals in the topsoil within the sixth ring road in Beijing, a total of 46 soil samples were collected, and the concentrations of twelve elements (Nickel, Ni, Lithium, Li, Vanadium, V, Cobalt, Co, Barium, Ba, Strontium, Sr, Chrome, Cr, Molybdenum, Mo, Copper, Cu, Cadmium, Cd, Zinc, Zn, Lead, Pb were analyzed. Geostatistics and multivariate statistics were conducted to identify spatial distribution characteristics and sources. In addition, the health risk of the analyzed heavy metals to humans (adult was evaluated by an U.S. Environmental Protection Agency health risk assessment model. The results indicate that these metals have notable variation in spatial scale. The concentration of Cr was high in the west and low in the east, while that of Mo was high in the north and low in the south. High concentrations of Cu, Cd, Zn, and Pb were found in the central part of the city. The average enrichment degree of Cd is 5.94, reaching the standard of significant enrichment. The accumulation of Cr, Mo, Cu, Cd, Zn, and Pb is influenced by anthropogenic activity, including vehicle exhaustion, coal burning, and industrial processes. Health risk assessment shows that both non-carcinogenic and carcinogenic risks of selected heavy metals are within the safety standard and the rank of the carcinogenic risk of the four heavy metals is Cr > Co > Ni > Cd.

  5. Spatial sediment variability in a tropical tide dominated estuary: Sources and drivers

    Science.gov (United States)

    Sousa, Silvia H. M.; Ferreira, Paulo A. L.; Martins, Maria V. A.; Siegle, Eduardo; Amaral, Paula G. C.; Figueira, Rubens C. L.; Yamashita, Cintia; Rodrigues, André R.; Mahiques, Michel M.

    2016-12-01

    Surficial sediment composition and spatial variability reflect the dynamics and level of natural and anthropogenic impact in estuarine systems. The aim of this study is to evaluate some key environmental and sedimentary variables, as well as to evaluate the current environmental quality in the tide-dominated Caravelas estuarine system (Brazil). Sixty-five surficial sediment samples were studied for grain size as well as calcium carbonate, total organic carbon, total nitrogen, metals, semi-metals and rare earth elements and for organic matter δ13C. Based on the spatial distribution of these data and summarizing our findings, three sectors can be individualized in the Caravelas estuarine system: i. Barra Velha inlet; ii. the main channel of the Caravelas estuary, and iii. the channel interconnecting Caravelas and Nova Viçosa estuaries. In the inlet the sedimentary organic matter is provided essentially by marine sources, which corroborates the small continental input. Freshwater dissolved organic carbon and particulate organic carbon occur in the interconnecting channel, proving the occurrence of the residual transport towards the Caravelas estuary, with continental contribution towards Caravelas River. The geochemical fingerprint indicates that the Barreiras Group, composed by Neogene terrigenous deposits, located west of the study area, as an important source of terrigenous material to the entire Caravelas estuary system. The higher values of heavy rare earth elements (between 20 and 30 mg kg-1) in the northern sector of the study area may be related to the high degree of chemical weathering in magmatic or metamorphic rocks, which occur to the north of the study area.

  6. Particulate air pollution in six Asian cities: Spatial and temporal distributions, and associated sources

    Science.gov (United States)

    Kim Oanh, N. T.; Upadhyay, N.; Zhuang, Y.-H.; Hao, Z.-P.; Murthy, D. V. S.; Lestari, P.; Villarin, J. T.; Chengchua, K.; Co, H. X.; Dung, N. T.; Lindgren, E. S.

    A monitoring program for particulate matter pollution was designed and implemented in six Asian cities/metropolitan regions including Bandung, Bangkok, Beijing, Chennai, Manila, and Hanoi, within the framework of the Asian regional air pollution research network (AIRPET), coordinated by the Asian Institute of Technology. As uniform the methodologies as possible were intended with an established QA/QC procedure in order to produce reliable and comparable data by the network. The monsoon effects and seasonal changes in the sources/activities require long-term monitoring to understand the nature of air pollution in the cities. During phase 1 (2001-2004) of the AIRPET around 3000 fine and coarse particulate matter samples were collected from characteristic urban sites, which provide insight into temporal and spatial variations of PM in the cities. In all six cities, the levels of PM 10 and PM 2.5 were found high, especially during the dry season, which frequently exceeded the corresponding 24 h US EPA standards at a number of sites. The average concentrations of PM 2.5 and PM 10 in the cities ranged, respectively, 44-168 and 54-262 μg m -3 in the dry season, and 18-104 and 33-180 μg m -3 in the wet season. Spatial and temporal distribution of PM in each city, the ratios of PM 2.5 to PM 10, and the reconstructed mass were presented which provide useful information on possible PM sources in the cities. The findings help to understand the nature of particulate matter air pollution problems in the selected cities/metropolitan regions.

  7. Estimation of high altitude Martian dust parameters

    Science.gov (United States)

    Pabari, Jayesh; Bhalodi, Pinali

    2016-07-01

    Dust devils are known to occur near the Martian surface mostly during the mid of Southern hemisphere summer and they play vital role in deciding background dust opacity in the atmosphere. The second source of high altitude Martian dust could be due to the secondary ejecta caused by impacts on Martian Moons, Phobos and Deimos. Also, the surfaces of the Moons are charged positively due to ultraviolet rays from the Sun and negatively due to space plasma currents. Such surface charging may cause fine grains to be levitated, which can easily escape the Moons. It is expected that the escaping dust form dust rings within the orbits of the Moons and therefore also around the Mars. One more possible source of high altitude Martian dust is interplanetary in nature. Due to continuous supply of the dust from various sources and also due to a kind of feedback mechanism existing between the ring or tori and the sources, the dust rings or tori can sustain over a period of time. Recently, very high altitude dust at about 1000 km has been found by MAVEN mission and it is expected that the dust may be concentrated at about 150 to 500 km. However, it is mystery how dust has reached to such high altitudes. Estimation of dust parameters before-hand is necessary to design an instrument for the detection of high altitude Martian dust from a future orbiter. In this work, we have studied the dust supply rate responsible primarily for the formation of dust ring or tori, the life time of dust particles around the Mars, the dust number density as well as the effect of solar radiation pressure and Martian oblateness on dust dynamics. The results presented in this paper may be useful to space scientists for understanding the scenario and designing an orbiter based instrument to measure the dust surrounding the Mars for solving the mystery. The further work is underway.

  8. High resolution satellite derived erodibility factors for WRF/Chem windblown dust simulations in Argentina

    Science.gov (United States)

    Cremades, Pablo Gabriel; Fernandez, Rafael Pedro; Allend, David; Mulena, Celeste; Puliafito, Salvador Enrique

    2017-04-01

    A proper representation of dust sources is critical to accurately predict atmospheric particle concentrations in regional windblown dust simulations. The Weather Research and Forecasting model with Chemistry (WRF/Chem) includes a topographic-based erodibility map originally conceived for global scale modeling, which fails to identify the geographical location of dust sources in many regions of Argentina. Therefore, this study aims at developing a method to obtain a high-resolution erodibility map suitable for regional or local scale modeling using WRF/Chem. We present two independent approaches based on global methods to estimate soil erodibility using satellite retrievals, i.e. topography from the Shuttle Radar Topography Mission (SRTM) and surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). Simulation results of a severe Zonda wind episode in the arid central-west Argentina serve as bases for the analysis of these methods. Simulated dust concentration at surface level is compared with particulate matter measurements at one site in Mendoza city. In addition, we use satellite aerosol optical depth (AOD) retrievals to investigate model performance in reproducing spatial distribution of dust emissions. The erodibility map based on surface reflectance from MODIS improves the representation of small scale features, and increases the overall dust aerosol loading with respect to the standard map included by default. Simulated concentrations are in good agreement with measurements as well as satellite derived dust spatial distribution.

  9. Assessment of MODIS-Derived Visible and Near-IR Aerosol Optical Properties and their Spatial Variability in the Presence of Mineral Dust

    Science.gov (United States)

    Redemann, J.; Zhang, Q.; Schmid, B.; Russell, P. B.; Livingston, J. M.; Jonsson, H.; Remer, L. A.

    2006-01-01

    Mineral dust aerosol is among the most difficult aerosol species to measure quantitatively from space. In this paper, we evaluate MODIS retrievals of spectral aerosol optical depth (AOD) from the visible to the near-IR off the US West Coast using measurements taken by the NASA Ames Airborne Tracking Sunphotometer, AATS-14, during the EVE (Extended-MODIS-lambda Validation Experiment, 2004) campaign in April of 2004. In EVE, a total of 35 and 49 coincident over-ocean suborbital measurements at the nominal level-2 retrieval scale of 10 km x 10 km were collected for Terra and Aqua, respectively. For MODIS-Terra about 80% of the AOD retrievals are within the estimated uncertainty, DELTA tau = plus or minus 0.03 plus or minus 0.05 tau; this is true for both the visible (here defined to include 466-855 nm) and near-IR (here defined to include 1243-2119 nm) retrievals. For MODIS-Aqua about 45% of the AOD retrievals are within DELTA tau = plus or minus 0.03 plus or minus 0.05 tau; the fraction of near-IR retrievals that fall within this uncertainty range is about 27%. We found an rms difference of 0.71 between the sunphotometer snd MODIS-Aqua estimates of the visible (553-855 nm) Angstrom exponent, while the MODIS-Terra visible Angstrom exponents show an rms difference of only 0.29 when compared to AATS. The cause of the differences in performance between MODIS-Terra and MODIS-Aqua could be instrument calibration and needs to be explored further. The spatial variability of AOD between retrieval boxes as derived by MODIS is generally larger than that indicated by the sunphotometer data.

  10. Spatial distribution of anthropogoenic pollution acumulated on tree leaves, soil and street dust in the park area in the centre of Warsaw

    Science.gov (United States)

    Dytłow, Sylwia; Górka-Kostrubiec, Beata

    2015-04-01

    The magnetic method has been successfully used to evaluate and characterise the degree of air pollution. This method is based on investigation of properties of magnetic particles of pollution such as magnetic susceptibility, parameters of hysteresis loops and temperature-dependence of magnetic parameters etc. The motivation to undertake this study was to find the distribution of pollution emitted by traffic vehicles in a green area situated in urban environment. The investigated area is the oldest public park named Saxon Garden in the centre of Warsaw, Poland. The Saxon Garden is located between the very busy main road with tram line, two local streets (low traffic volume) and big plaza without car traffic and trees. In order to quantify the degree of pollution we measured magnetic susceptibility of pollution deposited on chestnut leaves (the most abundant tree species in the park), surface of the roads (street dust) and in soil from the park area. The highest values of magnetic susceptibility of pollution were observed on tree leaves located along the edges/borders of park area (190 [m3/kg]), directly adjacent to busy roads. The lowest values of magnetic susceptibility (20 [m3/kg]) were obtained for leave samples from the borders of park, directly adjacent to plaza and roads with low traffic volume. It was observed that the intensity of magnetic susceptibility decreases with the distance of pollution source i.e. main streets. A similar distribution of intensity of magnetic susceptibility was observed for the soil samples collected from park area. With the exception of a few samples, the magnetic susceptibility of soil samples were higher than for leave samples. Our study showed that the distribution of magnetic susceptibility of soil and leave samples correlate with the intensity of magnetic susceptibility of street dust taken from the road surfaces situated along the boundary of the park area. On the basis of the detailed research of the domain structure and

  11. Using the significant dust deposition event on the glaciers of Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009 to develop a method for dating and

    Directory of Open Access Journals (Sweden)

    G. Nosenko

    2013-02-01

    Full Text Available A significant desert dust deposition event occurred on Mt. Elbrus, Caucasus Mountains, Russia on 5 May 2009, where the deposited dust later appeared as a brown layer in the snow pack. An examination of dust transportation history and analysis of chemical and physical properties of the deposited dust were used to develop a new approach for high-resolution "provenancing" of dust deposition events recorded in snow pack using multiple independent techniques. A combination of SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived with HYSPLIT model and analysis of meteorological data enabled identification of dust source regions with high temporal (hours and spatial (ca. 100 km resolution. Dust, deposited on 5 May 2009, originated in the foothills of the Djebel Akhdar in eastern Libya where dust sources were activated by the intrusion of cold air from the Mediterranean Sea and Saharan low pressure system and transported to the Caucasus along the eastern Mediterranean coast, Syria and Turkey. Particles with an average diameter below 8 μm accounted for 90% of the measured particles in the sample with a mean of 3.58 μm, median 2.48 μm. The chemical signature of this long-travelled dust was significantly different from the locally-produced dust and close to that of soils collected in a palaeolake in the source region, in concentrations of hematite. Potential addition of dust from a secondary source in northern Mesopotamia introduced uncertainty in the "provenancing" of dust from this event. Nevertheless, the approach adopted here enables other dust horizons in the snowpack to be linked to specific dust transport events recorded in remote sensing and meteorological data archives.

  12. Spatial, temporal and source contribution assessments of black carbon over the northern interior of South Africa

    Science.gov (United States)

    Euphinia Chiloane, Kgaugelo; Beukes, Johan Paul; Gideon van Zyl, Pieter; Maritz, Petra; Vakkari, Ville; Josipovic, Miroslav; Derick Venter, Andrew; Jaars, Kerneels; Tiitta, Petri; Kulmala, Markku; Wiedensohler, Alfred; Liousse, Catherine; Vuyisile Mkhatshwa, Gabisile; Ramandh, Avishkar; Laakso, Lauri

    2017-05-01

    After carbon dioxide (CO2), aerosol black carbon (BC) is considered to be the second most important contributor to global warming. This paper presents equivalent black carbon (eBC) (derived from an optical absorption method) data collected from three sites in the interior of South Africa where continuous measurements were conducted, i.e. Elandsfontein, Welgegund and Marikana, as well elemental carbon (EC) (determined by evolved carbon method) data at five sites where samples were collected once a month on a filter and analysed offline, i.e. Louis Trichardt, Skukuza, Vaal Triangle, Amersfoort and Botsalano.Analyses of eBC and EC spatial mass concentration patterns across the eight sites indicate that the mass concentrations in the South African interior are in general higher than what has been reported for the developed world and that different sources are likely to influence different sites. The mean eBC or EC mass concentrations for the background sites (Welgegund, Louis Trichardt, Skukuza, Botsalano) and sites influenced by industrial activities and/or nearby settlements (Elandsfontein, Marikana, Vaal Triangle and Amersfoort) ranged between 0.7 and 1.1, and 1.3 and 1.4 µg m-3, respectively. Similar seasonal patterns were observed at all three sites where continuous measurement data were collected (Elandsfontein, Marikana and Welgegund), with the highest eBC mass concentrations measured from June to October, indicating contributions from household combustion in the cold winter months (June-August), as well as savannah and grassland fires during the dry season (May to mid-October). Diurnal patterns of eBC at Elandsfontein, Marikana and Welgegund indicated maximum concentrations in the early mornings and late evenings, and minima during daytime. From the patterns it could be deduced that for Marikana and Welgegund, household combustion, as well as savannah and grassland fires, were the most significant sources, respectively.Possible contributing sources were

  13. Spatially and Temporally Refined Sources of Black Carbon Aerosols in the Arctic in spring

    Science.gov (United States)

    Qi, L.; Li, Q.; Mao, Y.; Chen, Y.; Randerson, J. T.; Wang, Q.; Hao, W. M.

    2014-12-01

    Black carbon (BC) aerosols play a substantial role in the rapid warming of the Arctic. We systematically evaluate the simulation of BC vertical profile (ARCTAS and ARCPAC flights), surface concentrations and concentrations in snow (Doherty et al., 2010) in the Arctic in spring using a global chemical transport model GEOS-Chem. We also provide highly spatially (2° lat ×2.5° lon) and temporally resolved source estimates of surface BC concentrations using GEOS-Chem adjoint. Results showed that the vertical profiles of BC agree with the aircraft observations from surface to 10 km within 50%. The monthly mean regional averaged BC concentrations in snow in Alaska, Arctic Ocean, Canada, Greenland and Russia agree with the observations within 40%, while the mean BC concentrations in snow in Svalbard and Norway agree with the observations within a factor of 3 because of inaccurate simulation of snow precipitation in GEOS5. We found Asian anthropogenic sources contributed 20-50% of BC concentrations through troposphere and in snow in the Arctic and are the major contributors in most regions. Adjoint analysis showed that BC concentrations of about 10 ng/m3 (30-100% of the total Asian contribution) observed at the surface stations are attributed to emissions emitted by Asian anthropogenic sources 30 days before the observation, and these background BC aerosols were transported to the station by circum-polar-vortex. Previous source estimates that repeated identified Europe as the major contributor of BC in the Arctic only trace back for 5 to 10 days and do not capture the background contribution from Asia. Russian biomass burning is important in mid-troposphere and accounts for 60% of total BC at 4-5 km. The relative contribution from different sources estimated by the adjoint of GEOS-Chem agrees with the forward estimate within 10%. Moreover, the adjoint analysis enables us to pinpoint the major sources to grid box level. Results showed that for surface observations

  14. Accuracy of core mass estimates in simulated observations of dust emission

    CERN Document Server

    Malinen, J; Collins, D C; Lunttila, T; Padoan, P

    2010-01-01

    We study the use of sub-millimetre dust emission in the estimation of the masses of molecular cloud cores. We want to determine the reliability of the mass estimates and at what level the observational biases are visible in the derived clump mass spectra. We use magnetohydrodynamic simulations and radiative transfer calculations to produce synthetic observations of dust emission. The synthetic maps have a spatial resolution and noise levels typical of the current Herschel surveys. Based on these data we estimate the dust temperatures and the column densities and compare the 'observed' core masses to the true values. We study the effects of spatial variations of dust properties. With high resolution adaptive mesh refinement simulations we also investigate how protostellar sources embedded in the cores affect the mass estimates. The shape, although not the position, of the mass spectrum is very reliable against observational errors. However, the core masses will be strongly underestimated in cores that have opt...

  15. Characterizing and tracing the dust sources of Lakes Sihailongwan and Huguangyan Maar in NE and SE China over the past 80 kyrs

    Science.gov (United States)

    Zaarur, Shikma; Stein, Mordechai; Mingram, Jens; Erel, Yigal

    2017-04-01

    A major challenge in the field of quaternary paleoclimate lies in reconstructing and understanding changes in atmospheric circulation and its relation to global and regional climate patterns. In this study, we use mineralogical, chemical and isotopic signatures of fine size particles in lake sediments to trace the sources of dust, as a tool to understand the synoptic patterns in East Asia during the past ˜80 kyrs. The study focuses on sediments from two maar lakes: Sihailongwan and Huguangyan in NE and SE China, respectively. These two are ideal for our study; they are hydrologically confined and do not drain any rivers or streams that introduce additional particle sources other than the volcanic rims and windblown dust. Sediment cores from both lakes were obtained by the German-Chinese drilling project (Mingram et al. 2004). Both cores have been previously dated and their general composition had been characterized (Mingram et al. 2004, Zhu et al. 2013). To characterize the local signature we additionally collected sediments from the rim and the vicinity of the lakes. Because we are interested in windblown particles, we concentrate on fine sediment fraction (material. Sr and Nd isotope ratios of materials from the lakes' rim and vicinity display large variations (87Sr/86Sr and ɛNd values of 0.7042-0.7202 and 6.0 to -8.8 for, respectively) and form two distinct mixing lines between the local basalt and two different end members. Isotopic values of core samples fall between the two lines and likely represent shifts in the relative contribution of each source.

  16. The chemotherapeutic agent paclitaxel selectively impairs learning while sparing source memory and spatial memory.

    Science.gov (United States)

    Smith, Alexandra E; Slivicki, Richard A; Hohmann, Andrea G; Crystal, Jonathon D

    2017-03-01

    Chemotherapeutic agents are widely used to treat patients with systemic cancer. The efficacy of these therapies is undermined by their adverse side-effect profiles such as cognitive deficits that have a negative impact on the quality of life of cancer survivors. Cognitive side effects occur across a variety of domains, including memory, executive function, and processing speed. Such impairments are exacerbated under cognitive challenges and a subgroup of patients experience long-term impairments. Episodic memory in rats can be examined using a source memory task. In the current study, rats received paclitaxel, a taxane-derived chemotherapeutic agent, and learning and memory functioning was examined using the source memory task. Treatment with paclitaxel did not impair spatial and episodic memory, and paclitaxel treated rats were not more susceptible to cognitive challenges. Under conditions in which memory was not impaired, paclitaxel treatment impaired learning of new rules, documenting a decreased sensitivity to changes in experimental contingencies. These findings provide new information on the nature of cancer chemotherapy-induced cognitive impairments, particularly regarding the incongruent vulnerability of episodic memory and new learning following treatment with paclitaxel.

  17. Spatially Resolved Elemental Analysis, Spectroscopy and Diffraction at the GSECARS Sector at the Advanced Photon Source

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Stephen R.; Lanzirotti, Antonio; Newville, Matthew; Rivers, Mark L.; Eng, Peter; Lefticariu, Liliana

    2017-01-01

    X-ray microprobes (XRM) coupled with high-brightness synchrotron X-ray facilities are powerful tools for environmental biogeochemistry research. One such instrument, the XRM at the Geo Soil Enviro Center for Advanced Radiation Sources Sector 13 at the Advanced Photon Source (APS; Argonne National Laboratory, Lemont, IL) was recently improved as part of a canted undulator geometry upgrade of the insertion device port, effectively doubling the available undulator beam time and extending the operating energy of the branch supporting the XRM down to the sulfur K edge (2.3 keV). Capabilities include rapid, high-resolution, elemental imaging including fluorescence microtomography, microscale X-ray absorption fine structure spectroscopy including sulfur K edge capability, and microscale X-ray diffraction. These capabilities are advantageous for (i) two-dimensional elemental mapping of relatively large samples at high resolution, with the dwell times typically limited only by the count times needed to obtain usable counting statistics for low concentration elements, (ii) three-dimensional imaging of internal elemental distributions in fragile hydrated specimens, such as biological tissues, avoiding the need for physical slicing, (iii) spatially resolved speciation determinations of contaminants in environmental materials, and (iv) identification of contaminant host phases. In this paper, we describe the XRM instrumentation, techniques, applications demonstrating these capabilities, and prospects for further improvements associated with the proposed upgrade of the APS.

  18. Dust Extinction Curves and Ly-$\\alpha$ Forest Flux Deficits for Use in Modeling GRB Afterglows and All Other Extragalactic Point Sources

    CERN Document Server

    Reichart, D E

    1999-01-01

    Since gamma-ray burst afterglows were first detected in 1997, the relativistic fireball model has emerged as the leading theoretical explanation of the afterglows. In this paper, we present a very general, Bayesian inference formalism with which this, or any other, afterglow model can be tested, and with which the parameter values of acceptable models can be constrained, given the available photometry. However, before model comparison or parameter estimation can be attempted, one must also consider the physical processes that affect the afterglow as it propagates along the line of sight from the burst source to the observer. Namely, how does extinction by dust, both in the host galaxy and in our galaxy, and absorption by the Ly-alpha forest and by H I in the host galaxy, change the intrinsic spectrum of the afterglow? Consequently, we also present in this paper a very general, eight-parameter dust extinction curve model, and a two-parameter model of the Ly-alpha forest flux deficit versus redshift distributio...

  19. Detailed modelling of a large sample of Herschel sources in the Lockman Hole: identification of cold dust and of lensing candidates through their anomalous SEDs

    CERN Document Server

    Rowan-Robinson, Michael; Wardlow, Julie; Farrah, Duncan; Oliver, Seb; Bock, Jamie; Clarke, Charlotte; Clements, David; Ibar, Edo; Gonzalez-Solares, Eduardo; Marchetti, Lucia; Scott, Douglas; Smith, Anthony; Vaccari, Mattia; Valtchanov, Ivan

    2014-01-01

    We have studied in detail a sample of 967 SPIRE sources with 5-sigma detections at 350 and 500 micron and associations with Spitzer-SWIRE 24 micron galaxies in the HerMES-Lockman survey area, fitting their mid- and far-infrared, and submillimetre, SEDs in an automatic search with a set of six infrared templates. For almost 300 galaxies we have modelled their SEDs individually to ensure the physicality of the fits. We confirm the need for the new cool and cold cirrus templates, and also of the young starburst template, introduced in earlier work. We also identify 109 lensing candidates via their anomalous SEDs and provide a set of colour-redshift constraints which allow lensing candidates to be identified from combined Herschel and Spitzer data. The picture that emerges of the submillimetre galaxy population is complex, comprising ultraluminous and hyperluminous starbursts, lower luminosity galaxies dominated by interstellar dust emission, lensed galaxies and galaxies with surprisingly cold (10-13K) dust. 11 %...

  20. Dust, Climate, and Human Health

    Science.gov (United States)

    Maynard, N. G.

    2003-12-01

    Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health

  1. Optimizing Saharan dust CALIPSO retrievals

    Directory of Open Access Journals (Sweden)

    V. Amiridis

    2013-06-01

    Full Text Available We demonstrate improvements in CALIPSO dust extinction retrievals over North Africa and Europe when corrections are applied regarding the Saharan dust lidar ratio assumption, the separation of dust portion in detected dust mixtures, and the averaging scheme introduced in the Level 3 CALIPSO product. First, a universal, spatially constant lidar ratio of 58 sr instead of 40 sr is applied to individual Level 2 dust-related backscatter products. The resulting aerosol optical depths show an improvement compared with synchronous and co-located AERONET measurements. An absolute bias of the order of −0.03 has been found, improving on the statistically significant biases of the order of −0.10 reported in the literature for the original CALIPSO product. When compared with the MODIS co-located AOD product, the CALIPSO negative bias is even less for the lidar ratio of 58 sr. After introducing the new lidar ratio for the domain studied, we examine potential improvements to the climatological CALIPSO Level 3 extinction product: (1 by introducing a new methodology for the calculation of pure dust extinction from dust mixtures and (2 by applying an averaging scheme that includes zero extinction values for the non-dust aerosol types detected. The scheme is applied at a horizontal spatial resolution of 1° × 1° for ease of comparison with the instantaneous and co-located dust extinction profiles simulated by the BSC-DREAM8b dust model. Comparisons show that the extinction profiles retrieved with the proposed methodology reproduce the well-known model biases per sub-region examined. The very good agreement of the proposed CALIPSO extinction product with respect to AERONET, MODIS and the BSC-DREAM8b dust model, makes this dataset an ideal candidate for the provision of an accurate and robust multi-year dust climatology over North Africa and Europe.

  2. Analysing and correcting the differences between multi-source and multi-scale spatial remote sensing observations.

    Science.gov (United States)

    Dong, Yingying; Luo, Ruisen; Feng, Haikuan; Wang, Jihua; Zhao, Jinling; Zhu, Yining; Yang, Guijun

    2014-01-01

    Differences exist among analysis results of agriculture monitoring and crop production based on remote sensing observations, which are obtained at different spatial scales from multiple remote sensors in same time period, and processed by same algorithms, models or methods. These differences can be mainly quantitatively described from three aspects, i.e. multiple remote sensing observations, crop parameters estimation models, and spatial scale effects of surface parameters. Our research proposed a new method to analyse and correct the differences between multi-source and multi-scale spatial remote sensing surface reflectance datasets, aiming to provide references for further studies in agricultural application with multiple remotely sensed observations from different sources. The new method was constructed on the basis of physical and mathematical properties of multi-source and multi-scale reflectance datasets. Theories of statistics were involved to extract statistical characteristics of multiple surface reflectance datasets, and further quantitatively analyse spatial variations of these characteristics at multiple spatial scales. Then, taking the surface reflectance at small spatial scale as the baseline data, theories of Gaussian distribution were selected for multiple surface reflectance datasets correction based on the above obtained physical characteristics and mathematical distribution properties, and their spatial variations. This proposed method was verified by two sets of multiple satellite images, which were obtained in two experimental fields located in Inner Mongolia and Beijing, China with different degrees of homogeneity of underlying surfaces. Experimental results indicate that differences of surface reflectance datasets at multiple spatial scales could be effectively corrected over non-homogeneous underlying surfaces, which provide database for further multi-source and multi-scale crop growth monitoring and yield prediction, and their corresponding

  3. Automobile traffic as a possible source of PCB and PAH in road dust; Biltrafikk som mulig kilde for PCB og PAH i veistoev

    Energy Technology Data Exchange (ETDEWEB)

    Schlabach, Martin

    1998-10-01

    This report discusses the results of a Norwegian investigation of road traffic as a source of PCB. The first part of the programme was source oriented. The economy of the project was limited and only simple measurements could be made. The following tests could be made relatively easily and without specialized equipment: soot samples directly from tailpipes, samples of tyres and asphalt. The results cannot give adequate emission factors, but may give some indication of the importance of the sources. The second part of the programme is recipient oriented and is based on samples of road dust taken previously in an investigation of the role of studded tyres. Soot samples of all three types (with/without catalytic converter, and diesel) and the new asphalt sample all showed very low values of PCB, close to the detection limit. No influence of road salt on the PCB content of the soot samples was found. The concentration of PCB in samples from auto tyres and old asphalt was well above the detection limit. Soot samples from private cars without catalytic converters showed the highest concentration of PAH. Soot samples from private cars with catalytic converters were significantly lower in PAH while the samples from buses were the lowest. The principle source of PCB from road traffic appears to be the abrasion of tyres and asphalt. Exhaust gas is less of a problem, at least with regard to PCB bound to particles.

  4. Deserts and holy mountains of medieval Serbia: Written sources, spatial patterns, architectural designs

    Directory of Open Access Journals (Sweden)

    Popović Danica

    2007-01-01

    meaning and the function of the monastic locales labeled as deserts and holy mountains (and, in a limited number of cases, also known as caves. The most important conclusions that may be drawn would be the following: the terms are interchangeable and were used both in a broader and a narrower sense, but in either case in reference to the space intended for higher forms of monastic life. A particularly broad range of meanings had the term desert which could refer to a distinct locale, as a rule a river gorge, or a mountain inhabited by hermits, but also a cave hermitage, the hesychasterion of a coenobitic community. The distinct forms of monastic life in such areas were communities of two or three or a few monks, organized as a skete or as a cell. In the deserts and mountains hermits primarily pursued the practice of 'agon and hesychia', but were also engaged in manuscript copying - an important peculiarity of Serbian eremitic monasticism. Finally, such locales were thought of by their dwellers as spiritual cities and the narrow path leading to Heavenly Jerusalem. The other thematic focus is an analysis of spatial patterns and architectural structures based on the relevant examples studied so far. Different types of monastic communities functioning as deserts were considered, from the point of view of their spatial situation and their relationship to the coenobia. In this context, field research identified examples of the so-called internal deserts, which was reconfirmed by the records from written sources. Special attention was given to the mechanism for creating a holy mount in the Serbian environment, according to the recognizable, athonite model. Also analyzed were architectural solutions characteristic of Serbian monastic deserts, from the simplest ones such as wooden huts and walled-up caves to monumental multi-storied edifices, equipped with different features. Finally, the conclusions that have been reached serve as a basis for defining future priorities in the

  5. Spatially open Friedmann--Robertson--Walker Universe fueled with interacting sources

    CERN Document Server

    Dariescu, Marina-Aura

    2016-01-01

    In the present paper, we are analyzing the $k=-1-$FRW Universe with two interacting ideal fluids. The energy densities and the pressures are used to derive the corresponding Equations of State. For a particular form of the interaction term between the two fluids, it turns out that the Universe is filled with a mixture of dust and radiation.

  6. Simulation of the Radiative Impact of High Dust Loading during a Dust Storm in March 2012

    Science.gov (United States)

    Puthan Purakkal, J.; Kalenderski, S.; Stenchikov, G. L.

    2013-12-01

    We investigated a severe dust storm that developed over vast areas of the Middle East on 18-19 March 2012 and affected Saudi Arabia, Sudan, Egypt, Jordan, United Arab Emirates, Bahrain, Qatar, Oman, Kuwait, Iraq, Iran, Israel, and Pakistan. The visible aerosol optical depth recorded by the AERONET station on the KAUST campus (22.30o N 39.10o E) during the storm reached 4.5, exceeding the average level by an order of magnitude. To quantify the effects of the dust on atmospheric radiation and dynamics, we analyzed available ground-based and satellite observations and conducted numerical simulations using a fully coupled meteorology-chemistry-aerosol model (WRF-Chem). The model was able to reproduce the spatial and temporal patterns of the aerosol optical depths (AOD) observed by airborne and ground-based instruments. The major dust sources included river valleys of lower Tigris and Euphrates in Iraq, desert areas in Kuwait, Iran, United Arab Emirates, central Arabia including Rub' al Khali, An Nafud, and Ad Dahna, as well as the Red Sea coast of the Arabian Peninsula. The total amount of dust generated across the entire domain during the period of the simulation reached 93.76 Mt; 73.04 Mt of dust was deposited within the domain; 6.56 Mt of dust sunk in the adjacent sea waters, including 1.20 Mt that sedimented into the Red Sea. The model predicted a well-mixed boundary layer expanding up to 3.5 km in the afternoon. Some dust plumes were seen above the Planetary Boundary layer. In our simulations, mineral dust heated the lower atmosphere with a maximum heating rate of 9 K/day. The dust storm reduced the downwelling shortwave radiation at the surface to a maximum daily average value of -134 Wm-2 and the daily averaged long-wave forcing at the surface increased to 43 Wm-2. The combined short-wave cooling and long-wave warming effects of dust aerosols caused significant reduction in the surface air temperature -6.7 K at 1200 UTC on 19 March 2013.

  7. Incorporation of a spatial source distribution and a spatial sensor sensitivity in a laser ultrasound propagation model using a streamlined Huygens' principle.

    Science.gov (United States)

    Laloš, Jernej; Babnik, Aleš; Možina, Janez; Požar, Tomaž

    2016-03-01

    The near-field, surface-displacement waveforms in plates are modeled using interwoven concepts of Green's function formalism and streamlined Huygens' principle. Green's functions resemble the building blocks of the sought displacement waveform, superimposed and weighted according to the simplified distribution. The approach incorporates an arbitrary circular spatial source distribution and an arbitrary circular spatial sensitivity in the area probed by the sensor. The displacement histories for uniform, Gaussian and annular normal-force source distributions and the uniform spatial sensor sensitivity are calculated, and the corresponding weight distributions are compared. To demonstrate the applicability of the developed scheme, measurements of laser ultrasound induced solely by the radiation pressure are compared with the calculated waveforms. The ultrasound is induced by laser pulse reflection from the mirror-surface of a glass plate. The measurements show excellent agreement not only with respect to various wave-arrivals but also in the shape of each arrival. Their shape depends on the beam profile of the excitation laser pulse and its corresponding spatial normal-force distribution.

  8. PCB-containing wood floor finish is a likely source of elevated PCBs in residents' blood, household air and dust: a case study of exposure

    Science.gov (United States)

    Rudel, Ruthann A; Seryak, Liesel M; Brody, Julia G

    2008-01-01

    Background Polychlorinated biphenyls (PCBs) are persistent pollutants identified worldwide as human blood and breast milk contaminants. Because they bioaccumulate, consumption of meat, fish, and dairy products predicts human blood concentrations. PCBs were also used widely in building materials, including caulks and paints, but few studies have evaluated the contribution of these exposures to body burden. Methods In an earlier study, we detected PCBs in indoor air in 31% of 120 homes on Cape Cod, MA. Two of the homes had much higher concentrations than the rest, so we retested to verify the initial finding, evaluate blood PCB concentrations of residents, and identify the PCB source. Results Air and dust concentrations remained elevated over 5 years between initial and follow-up sampling. Blood serum concentrations of PCBs in residents of the homes were generally elevated above the 95th percentile of a representative sample of the US population. Serum concentrations in residents and air and dust concentrations were especially high in a home where a resident reported use of PCB-containing floor finish in the past, and where the floor of one room was sanded and refinished just prior to sample collection. Conclusion This case-study suggests that PCB residues in homes may be more significant contributors to overall exposure than diet for some people, and that use of a commercially-available PCB-containing wood floor finish in residences during the 1950s and 1960s is an overlooked but potentially important source of current PCB exposure in the general population. PMID:18201376

  9. PCB-containing wood floor finish is a likely source of elevated PCBs in residents' blood, household air and dust: a case study of exposure

    Directory of Open Access Journals (Sweden)

    Seryak Liesel M

    2008-01-01

    Full Text Available Abstract Background Polychlorinated biphenyls (PCBs are persistent pollutants identified worldwide as human blood and breast milk contaminants. Because they bioaccumulate, consumption of meat, fish, and dairy products predicts human blood concentrations. PCBs were also used widely in building materials, including caulks and paints, but few studies have evaluated the contribution of these exposures to body burden. Methods In an earlier study, we detected PCBs in indoor air in 31% of 120 homes on Cape Cod, MA. Two of the homes had much higher concentrations than the rest, so we retested to verify the initial finding, evaluate blood PCB concentrations of residents, and identify the PCB source. Results Air and dust concentrations remained elevated over 5 years between initial and follow-up sampling. Blood serum concentrations of PCBs in residents of the homes were generally elevated above the 95th percentile of a representative sample of the US population. Serum concentrations in residents and air and dust concentrations were especially high in a home where a resident reported use of PCB-containing floor finish in the past, and where the floor of one room was sanded and refinished just prior to sample collection. Conclusion This case-study suggests that PCB residues in homes may be more significant contributors to overall exposure than diet for some people, and that use of a commercially-available PCB-containing wood floor finish in residences during the 1950s and 1960s is an overlooked but potentially important source of current PCB exposure in the general population.

  10. The magnetic field of cortical current sources: the application of a spatial filtering model to the forward and inverse problems.

    Science.gov (United States)

    Tan, S; Roth, B J; Wikswo, J P

    1990-07-01

    We extend our theoretical model based on spatial filtering to determine the ability of a SQUID magnetometer to resolve 2 localized current sources in the brain. We find that in order to resolve 2 separated but coaxial cortical sources, the source-to-pickup coil distance must be comparable to the distance between the 2 sources. The size of the current sources affects the resolving power of a magnetometer, but an anisotropy of 3 in the cortical tissue does not produce a significant effect. The model also provides a solution of the inverse calculation, either to reconstruct the original current source distribution from the measured magnetic field, or to continue the field at the magnetometer inward towards the sources. Both the inverse and inward calculations are limited by the fact that the inverse filter function serves as a high-pass filter, which leads to instabilities at high spatial frequencies, particularly in the presence of noise. The instabilities can be minimized by choosing an appropriate window to attenuate the noise, but this in turn reduces the spatial resolution.

  11. Spatial and Temporal Variations of EC and OC Aerosol Combustion Sources in a Polluted Metropolitan Area

    Science.gov (United States)

    Mouteva, G.; Randerson, J. T.; Fahrni, S.; Santos, G.; Bush, S. E.; Ehleringer, J. R.; Czimczik, C. I.

    2015-12-01

    Anthropogenic emissions of carbonaceous aerosols are a major component of fine air particulate matter (PM2.5) in polluted metropolitan areas and in the global atmosphere. Elemental (EC) and organic carbon (OC) aerosols influence Earth's energy balance by means of direct and indirect pathways and EC has been suggested as a better indicator of public health impacts from combustion-related sources than PM mass. Quantifying the contribution of fossil fuel and biomass combustion to the EC and OC emissions and their temporal and spatial variations is critical for developing efficient legislative air pollution control measures and successful climate mitigation strategies. In this study, we used radiocarbon (14C) to separate and quantify fossil and biomass contributions to a time series of EC and OC collected at 3 locations in Salt Lake City (SLC). Aerosol samples were collected on quartz fiber filters and a modified OC/EC analyzer was used with the Swiss_4S protocol to isolate and trap the EC fraction. Together with the total carbon (TC) content of the samples, the EC was analyzed for its 14C content with accelerator mass spectrometry. The 14C of OC was derived as a mass balance difference between TC and EC. EC had an annual average fraction modern of 0.13±0.06 and did not vary significantly across seasons. OC had an annual average FM of 0.49±0.13, with the winter mean (0.43±0.11) lower than the summer mean (0.64±0.13) at the 5% significance level. While the 3 stations were chosen to represent a variety of environmental conditions within SLC, no major differences in this source partitioning were observed between stations. During winter, the major sources of air pollutants in SLC are motor vehicles and wood stove combustion and determining their relative contributions has been the subject of debate. Our results indicated that fossil fuels were the dominant source of carbonaceous aerosols during winter, contributing 87% or more of the total EC mass and 40-75% of the OC

  12. Comparing modeled and observed changes in mineral dust transport and deposition to Antarctica between the Last Glacial Maximum and current climates

    Energy Technology Data Exchange (ETDEWEB)

    Albani, Samuel [University of Siena, Graduate School in Polar Sciences, Siena (Italy); University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Mahowald, Natalie M. [Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Delmonte, Barbara; Maggi, Valter [University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Winckler, Gisela [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Columbia University, Department of Earth and Environmental Sciences, New York, NY (United States)

    2012-05-15

    Mineral dust aerosols represent an active component of the Earth's climate system, by interacting with radiation directly, and by modifying clouds and biogeochemistry. Mineral dust from polar ice cores over the last million years can be used as paleoclimate proxy, and provide unique information about climate variability, as changes in dust deposition at the core sites can be due to changes in sources, transport and/or deposition locally. Here we present results from a study based on climate model simulations using the Community Climate System Model. The focus of this work is to analyze simulated differences in the dust concentration, size distribution and sources in current climate conditions and during the Last Glacial Maximum at specific ice core locations in Antarctica, and compare with available paleodata. Model results suggest that South America is the most important source for dust deposited in Antarctica in current climate, but Australia is also a major contributor and there is spatial variability in the relative importance of the major dust sources. During the Last Glacial Maximum the dominant source in the model was South America, because of the increased activity of glaciogenic dust sources in Southern Patagonia-Tierra del Fuego and the Southernmost Pampas regions, as well as an increase in transport efficiency southward. Dust emitted from the Southern Hemisphere dust source areas usually follow zonal patterns, but southward flow towards Antarctica is located in specific areas characterized by southward displacement of air masses. Observations and model results consistently suggest a spatially variable shift in dust particle sizes. This is due to a combination of relatively reduced en route wet removal favouring a generalized shift towards smaller particles, and on the other hand to an enhanced relative contribution of dry coarse particle deposition in the Last Glacial Maximum. (orig.)

  13. Ultrahigh charging of dust grains by the beam−plasma method for creating a compact neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Akishev, Yu. S., E-mail: fav@triniti.ru; Karal’nik, V. B.; Petryakov, A. V.; Starostin, A. N.; Trushkin, N. I.; Filippov, A. V. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2016-01-15

    Generation of high-voltage high-current electron beams in a low-pressure (P = 0.1–1 Torr) gas discharge is studied experimentally as a function of the discharge voltage and the sort and pressure of the plasma-forming gas. The density of the plasma formed by a high-current electron beam is measured. Experiments on ultrahigh charging of targets exposed to a pulsed electron beam with an energy of up to 25 keV, an electron current density of higher than 1 A/cm{sup 2}, a pulse duration of up to 1 μs, and a repetition rate of up to 1 kHz are described. A numerical model of ultrahigh charging of dust grains exposed to a high-energy electron beam is developed. The formation of high-energy positive ions in the field of negatively charged plane and spherical targets is calculated. The calculations performed for a pulse-periodic mode demonstrate the possibility of achieving neutron yields of higher than 10{sup 6} s{sup –1} cm{sup –2} in the case of a plane target and about 10{sup 9} s{sup –1} in the case of 10{sup 3} spherical targets, each with a radius of 250 μm.

  14. Are fractured cliffs the source of cometary dust jets ? Insights from OSIRIS/Rosetta at 67P

    CERN Document Server

    Vincent, J -B; Pajola, M; Höfner, S; Sierks, H; Hu, X; Barbieri, C; Lamy, P L; Rodrigo, R; Koschny, D; Rickman, H; Keller, H U; A'Hearn, M F; Barucci, M A; Bertaux, J -L; Bertini, I; Besse, S; Bodewits, D; Cremonese, G; Da Deppo, V; Davidsson, B; Debei, S; De Cecco, M; El-Maarry, M R; Fornasier, S; Fulle, M; Groussin, O; Gutiérrez, P J; Gutiérrez-Marquez, P; Güttler, C; Hofmann, M; Hviid, S F; Ip, W -H; Jorda, L; Knollenberg, J; Kovacs, G; Kramm, J -R; Kührt, E; Küppers, M; Lara, L M; Lazzarin, M; Lin, Z -Y; Lowry, S; Marzari, F; Massironi, M; Moreno, F; Mottola, S; Naletto, G; Preusker, F; Scholten, F; Shi, X; Thomas, N; Toth, I; Tubiana, C

    2015-01-01

    Dust jets, i.e. fuzzy collimated streams of cometary material arising from the nucleus, have been observed in-situ on all comets since the Giotto mission flew by comet 1P/Halley in 1986. Yet their formation mechanism remains unknown. Several solutions have been proposed, from localized physical mechanisms on the surface/sub-surface (see review in Belton (2010)) to purely dynamical processes involving the focusing of gas flows by the local topography (Crifo et al. 2002). While the latter seems to be responsible for the larger features, high resolution imagery has shown that broad streams are composed of many smaller features (a few meters wide) that connect directly to the nucleus surface. We monitored these jets at high resolution and over several months to understand what are the physical processes driving their formation, and how this affects the surface. Using many images of the same areas with different viewing angles, we performed a 3-dimensional reconstruction of collimated jets, and linked them precise...

  15. The SAGE-Spec Spitzer Legacy program: the life-cycle of dust and gas in the Large Magellanic Cloud. Point source classification - III

    Science.gov (United States)

    Jones, O. C.; Woods, P. M.; Kemper, F.; Kraemer, K. E.; Sloan, G. C.; Srinivasan, S.; Oliveira, J. M.; van Loon, J. Th.; Boyer, M. L.; Sargent, B. A.; McDonald, I.; Meixner, M.; Zijlstra, A. A.; Ruffle, P. M. E.; Lagadec, E.; Pauly, T.; Sewiło, M.; Clayton, G. C.; Volk, K.

    2017-09-01

    The Infrared Spectrograph (IRS) on the {\\em Spitzer Space Telescope} observed nearly 800 point sources in the Large Magellanic Cloud (LMC), taking over 1,000 spectra. 197 of these targets were observed as part of the Sage-Spec Spitzer Legacy program; the remainder are from a variety of different calibration, guaranteed time and open time projects. We classify these point sources into types according to their infrared spectral features, continuum and spectral energy distribution shape, bolometric luminosity, cluster membership, and variability information, using a decision-tree classification method. We then refine the classification using supplementary information from the astrophysical literature. We find that our IRS sample is comprised substantially of YSO and H\\,{\\sc ii} regions, post-Main Sequence low-mass stars: (post-)AGB stars and planetary nebulae and massive stars including several rare evolutionary types. Two supernova remnants, a nova and several background galaxies were also observed. We use these classifications to improve our understanding of the stellar populations in the Large Magellanic Cloud, study the composition and characteristics of dust species in a variety of LMC objects, and to verify the photometric classification methods used by mid-IR surveys. We discover that some widely-used catalogues of objects contain considerable contamination and others are missing sources in our sample.

  16. Sources, solubility, and acid processing of aerosol iron and phosphorous over the South China Sea: East Asian dust and pollution outflows vs. Southeast Asian biomass burning

    Science.gov (United States)

    Hsu, S.-C.; Gong, G.-C.; Shiah, F.-K.; Hung, C.-C.; Kao, S.-J.; Zhang, R.; Chen, W.-N.; Chen, C.-C.; Chou, C. C.-K.; Lin, Y.-C.; Lin, F.-J.; Lin, S.-H.

    2014-08-01

    Iron and phosphorous are essential to marine microorganisms in vast regions in oceans worldwide. Atmospheric inputs are important allochthonous sources of Fe and P. The variability in airborne Fe deposition is hypothesized to serve an important function in previous glacial-interglacial cycles, contributing to the variability in atmospheric CO2 and ultimately the climate. Understanding the mechanisms underlying the mobilization of airborne Fe and P from insoluble to soluble forms is critical to evaluate the biogeochemical effects of these elements. In this study, we present a robust power-law correlation between fractional Fe solubility and non-sea-salt-sulfate / Total-Fe (nss-sulfate / FeT) molar ratio independent of distinct sources of airborne Fe of natural and/or anthropogenic origins over the South China Sea. This area receives Asian dust and pollution outflows and Southeast Asian biomass burning. This correlation is also valid for nitrate and total acids, demonstrating the significance of acid processing in enhancing Fe mobilization. Such correlations are also found for P, yet source dependent. These relationships serve as straightforward parameters that can be directly incorporated into available atmosphere-ocean coupling models that facilitate the assessment of Fe and P fertilization effects. Although biomass burning activity may supply Fe to the bioavailable Fe pool, pyrogenic soils are possibly the main contributors, not the burned plants. This finding warrants a multidisciplinary investigation that integrates atmospheric observations with the resulting biogeochemistry in the South China Sea, which is influenced by atmospheric forcings and nutrient dynamics with monsoons.

  17. Recently deglaciated high-altitude soils of the Himalaya: diverse environments, heterogenous bacterial communities and long-range dust inputs from the upper troposphere.

    Directory of Open Access Journals (Sweden)

    Blaz Stres

    Full Text Available BACKGROUND: The Himalaya with its altitude and geographical position forms a barrier to atmospheric transport, which produces much aqueous-particle monsoon precipitation and makes it the largest continuous ice-covered area outside polar regions. There is a paucity of data on high-altitude microbial communities, their native environments and responses to environmental-spatial variables relative to seasonal and deglaciation events. METHODOLOGY/PRINCIPAL FINDINGS: Soils were sampled along altitude transects from 5000 m to 6000 m to determine environmental, spatial and seasonal factors structuring bacterial communities characterized by 16 S rRNA gene deep sequencing. Dust traps and fresh-snow samples were used to assess dust abundance and viability, community structure and abundance of dust associated microbial communities. Significantly different habitats among the altitude-transect samples corresponded to both phylogenetically distant and closely-related communities at distances as short as 50 m showing high community spatial divergence. High within-group variability that was related to an order of magnitude higher dust deposition obscured seasonal and temporal rearrangements in microbial communities. Although dust particle and associated cell deposition rates were highly correlated, seasonal dust communities of bacteria were distinct and differed significantly from recipient soil communities. Analysis of closest relatives to dust OTUs, HYSPLIT back-calculation of airmass trajectories and small dust particle size (4-12 µm suggested that the deposited dust and microbes came from distant continental, lacustrine and marine sources, e.g. Sahara, India, Caspian Sea and Tibetan plateau. Cyanobacteria represented less than 0.5% of microbial communities suggesting that the microbial communities benefitted from (codeposited carbon which was reflected in the psychrotolerant nature of dust-particle associated bacteria. CONCLUSIONS/SIGNIFICANCE: The spatial

  18. [Spatial changes and sources of nitrate in Beijing urban ecosystem surface water].

    Science.gov (United States)

    Xu, Zhi-wei; Zhang, Xin-yu; Ren, Yu-fen; Sun, Xiao-min; Wang, Xiao-ke; Wang, Sheng-zhong

    2012-08-01

    The spatial variation in nitrate-nitrogen (NO3- -N) concentrations in surface water of ten sampling sites in the Beijing urban ecosystem from Kunminghu Lake to Tonghui River were assessed using monitoring data from 2009 to 2010. Nitrogen sources were examined using a hydro-chemical method. The results showed that the average nitrate-N concentrations of surface water in the Beijing urban ecosystem ranged from 0.7-7.6 mg x L(-1), with concentrations at all sites affected by human activities to a varying degree. The nitrate-N concentrations in the Dongbianmen and Tonghui River located in the southeastern of Beijing ranged from 7.0-7.6 mg x L(-1) and were significantly higher than those in the upper reaches (P waste water, leakage from solid waste disposal and domestic wastewater mainly controlled nitrate distribution in the Beijing urban surface water. The results from this study suggest that surface water management should focus on downstream sites located in the southeastern region of Beijing such as the Dongbianmen and Tonghui River in the future.

  19. Newspaper archives + text mining = rich sources of historical geo-spatial data

    Science.gov (United States)

    Yzaguirre, A.; Smit, M.; Warren, R.

    2016-04-01

    Newspaper archives are rich sources of cultural, social, and historical information. These archives, even when digitized, are typically unstructured and organized by date rather than by subject or location, and require substantial manual effort to analyze. The effort of journalists to be accurate and precise means that there is often rich geo-spatial data embedded in the text, alongside text describing events that editors considered to be of sufficient importance to the region or the world to merit column inches. A regional newspaper can add over 100,000 articles to its database each year, and extracting information from this data for even a single country would pose a substantial Big Data challenge. In this paper, we describe a pilot study on the construction of a database of historical flood events (location(s), date, cause, magnitude) to be used in flood assessment projects, for example to calibrate models, estimate frequency, establish high water marks, or plan for future events in contexts ranging from urban planning to climate change adaptation. We then present a vision for extracting and using the rich geospatial data available in unstructured text archives, and suggest future avenues of research.

  20. Spatial distribution, enrichment, and source of environmentally important elements in Batticaloa lagoon, Sri Lanka.

    Science.gov (United States)

    Adikaram, Madurya; Pitawala, Amarasooriya; Ishiga, Hiroaki; Jayawardana, Daham

    2017-01-01

    The present paper is the first documentation of distribution and contamination status of environmentally important elements of superficial sediments in the Batticaloa lagoon that is connected to the largest bay of the world. Surface sediment samples were collected from 34 sites covering all over the lagoon. Concentrations of elements such as As, Cr, Cu, Fe, Nb, Ni, Pb, Sc, Sr, Th, V, Y, Zn, and Zr were measured by X-ray florescence analysis. Geochemically, the lagoon has three different zones that were influenced mainly by fresh water sources, marine fronts, and intermediate mixing zones. The marine sediment quality standards indicate that Zr and Th values are exceeded throughout the lagoon. According to the freshwater sediment quality standards, Cr levels of all sampling sites exceed the threshold effect level (TEL) and 17 % of them are even above the probable effect level (PEL). Most sampling sites of the channel discharging areas show minor enrichment of Cu, Ni, and Zn with respect to the TEL. Contamination indices show that the lagoon mouth area is enriched with As. Statistical analysis implies that discharges from agricultural channel and marine fluxes of the lagoon effects on the spatial distribution of measured elements. Further research is required to understand the rate of contamination in the studied marine system.

  1. Coastal dynamic and shoreline mapping: multi-sources spatial data analysis in Semarang Indonesia.

    Science.gov (United States)

    Marfai, Muh Aris; Almohammad, Hussein; Dey, Sudip; Susanto, Budi; King, Lorenz

    2008-07-01

    Semarang coastal area has geomorphologically complex processes, such as erosion-sedimentation, land subsidence, and tidal inundation hazard. Multi-years shoreline mapping is considered a valuable task for coastal monitoring and assessment. This paper presents maps illustrating the shoreline dynamic in a coastal area of Semarang-Indonesia using multi-sources spatial data. The segment data has been obtained by visual delineation of the topographic maps Year 1908, 1937, 1992 and Ikonos image Year 2003 as well as digital number (DN) value analysis and masking operation of Landsat MSS Year 1972 and Landsat ETM Year 2001. For the long period of almost 100 year, the shoreline dynamic in Semarang coastal area is dominated by sedimentation process. Shoreline extended to the sea as a result of man-made infrastructure and natural processes. The research's result was satisfactory and the method has proven to be effective considering lack of homogeneous data-series. However, some further improvement regarding geo-processing can be made and the accuracy can be tested in future version.

  2. Remote Operating Monitoring Of Spatial Stability Magnets On A Kurchatov Source Of Synchrotron Radiation

    CERN Document Server

    Barkovsky, E V; Martynenko, V V; Novikov, V A; Udin, L I

    2004-01-01

    During operation of the accelerator because of a nonuniform warm -up of the ring base and constructions of installation there are angular and linear displacements of bending and focusing magnets of a Big Accelerator Ring (BR) of a Kurchatov Source of Synchrotron Radiation. With the purpose of remote operating monitoring of a spatial position of elements BR was used anglemetrical control and measuring system with digital and analog registration in a real time mode. The results of the first stage of a monitoring BR have shown high informativity of the given instrumental - methodical means. The basic radiants of cyclical thermoelastic alternating strains are detected; the amplitudes of angular and linear displacements of magnets from different internal factors evaluated during operation of the accelerator. Is established, that the maximum radial angular and linear displacements of magnets are watched in 3,5-4 day after switching on of installation and achieve in max 30-35 seconds of an arc or 120-150 microns in ...

  3. Spatial distribution and source apportionment of PAHs in marine surface sediments of Prydz Bay, East Antarctica.

    Science.gov (United States)

    Xue, Rui; Chen, Ling; Lu, Zhibo; Wang, Juan; Yang, Haizhen; Zhang, Jie; Cai, Minghong

    2016-12-01

    This paper reports the concentrations of polycyclic aromatic hydrocarbons (PAHs) in marine sediments sampled from Prydz Bay, East Antarctica. Total PAH concentrations ranged from 12.95 to 30.93 ng/g, with a mean of 17.99 ± 5.57 ng/g. Two- and three-ring PAHs were the most abundant compounds found at the majority of the sampling stations of Prydz Bay. Long-range atmospheric transportation was found to play an important role in determining the spatial distribution of PAHs in the sediments sampled here. However, transport by ocean currents and release from melting glaciers were also found to influence PAH distributions in the sediments of East Antarctica. The vertical migration of PAHs in sediments showed a decreasing trend with depth, with higher concentrations in the relatively shallow-water regions (1000 m) of the Amery Basin and associated Canyons, respectively. A Pearson correlation analysis between PAH concentrations and sediment parameters demonstrated that PAHs has poor correlations with grain size, but has positive correlation with total organic carbon, indicated complex processing during transfer to remote environments. The results of qualitative and quantitative analyses indicate that the PAHs sampled here were derived mainly from a mixture of biomass combustion, traffic emissions, and petrogenic sources.

  4. Global budget of atmospheric carbonyl sulfide: Temporal and spatial variations of the dominant sources and sinks

    Science.gov (United States)

    Kettle, A. J.; Kuhn, U.; von Hobe, M.; Kesselmeier, J.; Andreae, M. O.

    2002-11-01

    The spatial and temporal variability of the global fluxes of carbonyl sulfide (COS) is discussed together with possible implications for total column atmospheric COS loading. The input of COS into the atmosphere is calculated as the sum of all known direct sources of COS plus the conversion of carbon disulfide (CS2) and dimethyl sulfide (DMS) to COS by atmospheric oxidation processes. Recent models are used to predict COS, CS2, and DMS release from the oceans and COS uptake by soils, plants, and oceans. This forward approach to constructing global integrated COS fluxes has a large associated range of uncertainty. The best guess global annual-integrated COS net flux estimate does not differ from zero within the range of estimated uncertainty, consistent with the observed absence of long-term trends in atmospheric COS loading. Interestingly, the hemispheric time-dependent monthly fluxes are very close in phase for the Northern and Southern Hemispheres. The monthly variation of the Northern Hemisphere flux seems to be driven primarily by high COS vegetation uptake in summer, while the monthly variation of the Southern Hemisphere flux appears to be driven mostly by high oceanic fluxes of COS, CS2, and DMS in summer.

  5. Understanding the spatial and temporal variability of water sources in a humid forested catchment

    Science.gov (United States)

    Pianezzola, Luisa; Zuecco, Giulia; Pozzoni, Santiago; Penna, Daniele; Borga, Marco

    2016-04-01

    The detailed understanding of the hydrological response of humid forested catchments is hampered by the marked spatial and temporal variability of water sources. In this work, we use environmental tracers (major ions, electrical conductivity and stable isotopes of water) coupled to hydrometric data to infer the main contributors to streamflow and their spatio-temporal variability during rainfall events in a small forested catchment in the Italian pre-Alps. Specifically, we aim to i) identify the main end-members for stream runoff; ii) evaluate their spatial and temporal variability, and iii) quantify the component fractions in stream runoff. Data collection took place in the 1.96-ha Ressi catchment between August 2012 and November 2015. Streamflow, precipitation, air temperature, shallow groundwater levels at six spatially-distributed locations and soil moisture at four locations along a riparian-hillslope transect were continuously measured. Monthly water samples were collected from precipitation, stream, shallow groundwater, soil water at 20 cm depth in two suction cups in the riparian and hillslope zone. Electrical conductivity was measured in the field by a portable meter, isotopic composition was determined by laser absorption spectroscopy and ionic concentrations by ion-chromatography. Samples for major ions were collected from September 2015 also during three rainfall-runoff events at high temporal frequency. End-member mixing analysis and tracer-based two- and three-component hydrograph separation techniques were employed, providing different scenarios of streamflow component fractions according to the use of isotopic data and of the three cations with largest concentrations (calcium, magnesium and sodium), and groundwater in different wells. Preliminary results reveal that precipitation, soil water in the riparian zone, and shallow groundwater are the main contributors to stream runoff. Riparian groundwater in the lower part of the catchment sustains

  6. Exploring the overabundance of ultraluminous X-ray sources in metal- and dust-poor local Lyman break analogs

    Science.gov (United States)

    Basu-Zych, Antara; Lehmer, Bret; Fragos, Tassos; Hornschemeier, Ann E.; Zezas, Andreas; Yukita, Mihoko; Ptak, Andrew

    2016-01-01

    We have studied high mass X-ray binary (HMXB) populations within two low-metallicity, starburst galaxies, Haro 11 and VV 114. These galaxies serve as analogs to high-redshift (z > 2) Lyman break galaxies, and within the larger sample of Lyman break analogs (LBAs) are sufficiently nearby (1039 erg s-1 ultraluminous X-ray sources, ULXs) in these low-metallicity galaxies, based on 8 detected ULXs. Comparing with the star-forming galaxy X-ray luminosity function (XLF), Haro 11 and VV 114 host ~4 times more LX>1040 erg s-1 sources than expected given their SFRs. We simulate the effects of source blending from crowded lower luminosity HMXBs using the star-forming galaxy XLF and then vary the XLF normalizations and bright-end slopes until we reproduce the observed point source luminosity distributions. Based on this analysis, we find that these LBAs have a shallower bright end slope than the standard XLF.

  7. Zodiacal light as an indicator of interplanetary dust

    Science.gov (United States)

    Weinberg, J. L.; Sparrow, J. G.

    1978-01-01

    The most striking feature of the night sky in the tropics is the zodiacal light, which appears as a cone in the west after sunset and in the east before sunrise. It is caused by sunlight scattered or absorbed by particles in the interplanetary medium. The zodiacal light is the only source of information about the integrated properties of the whole ensemble of interplanetary dust. The brightness and polarization in different directions and at different colors can provide information on the optical properties and spatial distribution of the scattering particles. The zodiacal light arises from two independent physical processes related to the scattering of solar continuum radiation by interplanetary dust and to thermal emission which arises from solar radiation that is absorbed by interplanetary dust and reemitted mainly at infrared wavelengths. Attention is given to observational parameters of zodiacal light, the methods of observation, errors and absolute calibration, and the observed characteristics of zodiacal light.

  8. Inferring the interplanetary dust properties from remote observations and simulations

    CERN Document Server

    Lasue, Jeremie; Fray, Nicolas; Cottin, Hervé

    2016-01-01

    Since in situ studies and interplanetary dust collections only provide a spatially limited amount of information about the interplanetary dust properties, it is of major importance to complete these studies with properties inferred from remote observations of light scattered and emitted, with interpretation through simulations. Physical properties of the interplanetary dust in the near-ecliptic symmetry surface, such as the local polarization, temperature and composition, together with their heliocentric variations, may be derived from scattered and emitted light observations, giving clues to the respective contribution of the particles sources. A model of light scattering by a cloud of solid particles constituted by spheroidal grains and aggregates thereof is used to interpret the local light scattering data. Equilibrium temperature of the same particles allows us to interpret the temperature heliocentric variations. A good fit of the local polarization phase curve, $P_{\\alpha}$, near 1.5~AU from the Sun is ...

  9. Allergies, asthma, and dust

    Science.gov (United States)

    Reactive airway disease - dust; Bronchial asthma - dust; Triggers - dust ... Things that make allergies or asthma worse are called triggers. Dust is a common trigger. When your asthma or allergies become worse due to dust, you are ...

  10. A three-dimensional point process model for the spatial distribution of disease occurrence in relation to an exposure source.

    Science.gov (United States)

    Grell, Kathrine; Diggle, Peter J; Frederiksen, Kirsten; Schüz, Joachim; Cardis, Elisabeth; Andersen, Per K

    2015-10-15

    We study methods for how to include the spatial distribution of tumours when investigating the relation between brain tumours and the exposure from radio frequency electromagnetic fields caused by mobile phone use. Our suggested point process model is adapted from studies investigating spatial aggregation of a disease around a source of potential hazard in environmental epidemiology, where now the source is the preferred ear of each phone user. In this context, the spatial distribution is a distribution over a sample of patients rather than over multiple disease cases within one geographical area. We show how the distance relation between tumour and phone can be modelled nonparametrically and, with various parametric functions, how covariates can be included in the model and how to test for the effect of distance. To illustrate the models, we apply them to a subset of the data from the Interphone Study, a large multinational case-control study on the association between brain tumours and mobile phone use.

  11. Dust in the arcs of Methone and Anthe

    CERN Document Server

    Sun, Kai-Lung; Spahn, Frank

    2015-01-01

    Methone and Anthe are two tiny moons (with diameter $<3$ km) in the inner part of Saturn's E ring. Both moons are embedded in an arc of dust particles. To understand the amount of micron-sized dust and their spatial distribution in these arcs, we model the source, dynamical evolution, and sinks of these dust in the arc. We assume hypervelocity impacts of micrometeoroids on the moons as source of these dust (Hedman et al., 2009), the so called impact-ejecta process (Krivov et al., 2003; Spahn et al., 2006). After ejecting and escaping from the moons, these micron-sized particles are subject to several perturbing forces, including gravitational perturbation from Mimas, oblateness of Saturn, Lorentz force, solar radiation pressure, and plasma drag. Particles can be either confined in the arcs due to corotational resonance with Mimas, as their source moons (Spitale et al., 2006; Cooper et al., 2008; Hedman et al., 2009), or pushed outward by plasma drag. Particle sinks are recollisions with the source moon, co...

  12. sLORETA current source density analysis of evoked potentials for spatial updating in a virtual navigation task.

    Science.gov (United States)

    Nguyen, Hai M; Matsumoto, Jumpei; Tran, Anh H; Ono, Taketoshi; Nishijo, Hisao

    2014-01-01

    Previous studies have reported that multiple brain regions are activated during spatial navigation. However, it is unclear whether these activated brain regions are specifically associated with spatial updating or whether some regions are recruited for parallel cognitive processes. The present study aimed to localize current sources of event related potentials (ERPs) associated with spatial updating specifically. In the control phase of the experiment, electroencephalograms (EEGs) were recorded while subjects sequentially traced 10 blue checkpoints on the streets of a virtual town, which were sequentially connected by a green line, by manipulating a joystick. In the test phase of the experiment, the checkpoints and green line were not indicated. Instead, a tone was presented when the subjects entered the reference points where they were then required to trace the 10 invisible spatial reference points corresponding to the checkpoints. The vertex-positive ERPs with latencies of approximately 340 ms from the moment when the subjects entered the unmarked reference points were significantly larger in the test than in the control phases. Current source density analysis of the ERPs by standardized low-resolution brain electromagnetic tomography (sLORETA) indicated activation of brain regions in the test phase that are associated with place and landmark recognition (entorhinal cortex/hippocampus, parahippocampal and retrosplenial cortices, fusiform, and lingual gyri), detecting self-motion (posterior cingulate and posterior insular cortices), motor planning (superior frontal gyrus, including the medial frontal cortex), and regions that process spatial attention (inferior parietal lobule). The present results provide the first identification of the current sources of ERPs associated with spatial updating, and suggest that multiple systems are active in parallel during spatial updating.

  13. sLORETA current source density analysis of evoked potentials for spatial updating in a virtual navigation task

    Directory of Open Access Journals (Sweden)

    Hai Minh Nguyen

    2014-03-01

    Full Text Available Previous studies have reported that multiple brain regions are activated during spatial navigation. However, it is unclear whether these activated brain regions are specifically associated with spatial updating or whether some regions are recruited for parallel cognitive processes. The present study aimed to localize current sources of event related potentials (ERPs associated with spatial updating specifically. In the control phase of the experiment, electroencephalograms (EEGs were recorded while subjects sequentially traced 10 blue checkpoints on the streets of a virtual town, which were sequentially connected by a green line, by manipulating a joystick. In the test phase of the experiment, the checkpoints and green line were not indicated. Instead, a tone was presented when the subjects entered the reference points where they were then required to trace the 10 invisible spatial reference points corresponding to the checkpoints. The vertex-positive ERPs with latencies of approximately 340 ms from the moment when the subjects entered the unmarked reference points were significantly larger in the test than in the control phases. Current source density analysis of the ERPs by sLORETA indicated activation of brain regions in the test phase that are associated with place and landmark recognition (entorhinal cortex/hippocampus, parahippocampal and retrosplenial cortices, fusiform and lingual gyri, detecting self-motion (posterior cingulate and posterior insular cortices, motor planning (superior frontal gyrus, including the medial frontal cortex, and regions that process spatial attention (inferior parietal lobule. The present results provide the first identification of the current sources of ERPs associated with spatial updating, and suggest that multiple systems are active in parallel during spatial updating.

  14. Applying spatial regression to evaluate risk factors for microbiological contamination of urban groundwater sources in Juba, South Sudan

    Science.gov (United States)

    Engström, Emma; Mörtberg, Ulla; Karlström, Anders; Mangold, Mikael

    2016-12-01

    This study developed methodology for statistically assessing groundwater contamination mechanisms. It focused on microbial water pollution in low-income regions. Risk factors for faecal contamination of groundwater-fed drinking-water sources were evaluated in a case study in Juba, South Sudan. The study was based on counts of thermotolerant coliforms in water samples from 129 sources, collected by the humanitarian aid organisation Médecins Sans Frontières in 2010. The factors included hydrogeological settings, land use and socio-economic characteristics. The results showed that the residuals of a conventional probit regression model had a significant positive spatial autocorrelation (Moran's I = 3.05, I-stat = 9.28); therefore, a spatial model was developed that had better goodness-of-fit to the observations. The most significant factor in this model (p-value 0.005) was the distance from a water source to the nearest Tukul area, an area with informal settlements that lack sanitation services. It is thus recommended that future remediation and monitoring efforts in the city be concentrated in such low-income regions. The spatial model differed from the conventional approach: in contrast with the latter case, lowland topography was not significant at the 5% level, as the p-value was 0.074 in the spatial model and 0.040 in the traditional model. This study showed that statistical risk-factor assessments of groundwater contamination need to consider spatial interactions when the water sources are located close to each other. Future studies might further investigate the cut-off distance that reflects spatial autocorrelation. Particularly, these results advise research on urban groundwater quality.

  15. Applying spatial regression to evaluate risk factors for microbiological contamination of urban groundwater sources in Juba, South Sudan

    Science.gov (United States)

    Engström, Emma; Mörtberg, Ulla; Karlström, Anders; Mangold, Mikael

    2017-06-01

    This study developed methodology for statistically assessing groundwater contamination mechanisms. It focused on microbial water pollution in low-income regions. Risk factors for faecal contamination of groundwater-fed drinking-water sources were evaluated in a case study in Juba, South Sudan. The study was based on counts of thermotolerant coliforms in water samples from 129 sources, collected by the humanitarian aid organisation Médecins Sans Frontières in 2010. The factors included hydrogeological settings, land use and socio-economic characteristics. The results showed that the residuals of a conventional probit regression model had a significant positive spatial autocorrelation (Moran's I = 3.05, I-stat = 9.28); therefore, a spatial model was developed that had better goodness-of-fit to the observations. The most significant factor in this model ( p-value 0.005) was the distance from a water source to the nearest Tukul area, an area with informal settlements that lack sanitation services. It is thus recommended that future remediation and monitoring efforts in the city be concentrated in such low-income regions. The spatial model differed from the conventional approach: in contrast with the latter case, lowland topography was not significant at the 5% level, as the p-value was 0.074 in the spatial model and 0.040 in the traditional model. This study showed that statistical risk-factor assessments of groundwater contamination need to consider spatial interactions when the water sources are located close to each other. Future studies might further investigate the cut-off distance that reflects spatial autocorrelation. Particularly, these results advise research on urban groundwater quality.

  16. Spatial and temporal variability of sources of ambient fine particulate matter (PM2.5) in California

    Science.gov (United States)

    Hasheminassab, S.; Daher, N.; Saffari, A.; Wang, D.; Ostro, B. D.; Sioutas, C.

    2014-11-01

    To identify major sources of ambient fine particulate matter (PM2.5, dp Simi Valley, Bakersfield, Fresno, San Jose, and Sacramento. Between five to nine sources of fine PM were identified at each sampling site, several of which were common among multiple locations. Secondary aerosols, including secondary ammonium nitrate and ammonium sulfate, were the most abundant contributor to ambient PM2.5 mass at all sampling sites, except for San Jose, with an annual average cumulative contribution of 26 to 63%, across the state. On an annual average basis, vehicular emissions (including both diesel and gasoline vehicles) were the largest primary source of fine PM at all sampling sites in southern California (17-18% of total mass), whereas in Fresno and San Jose, biomass burning was the most dominant primary contributor to ambient PM2.5 (27 and 35% of total mass, respectively), in general agreement with the results of previous source apportionment studies in California. In Bakersfield and Sacramento, vehicular emissions and biomass burning displayed relatively equal annual contributions to ambient PM2.5 mass (12 and 25%, respectively). Other commonly identified sources at all sites included aged and fresh sea salt and soil, which contributed to 0.5-13%, 2-27%, and 1-19% of the total mass, respectively, across all sites and seasons. In addition, a few minor sources were identified exclusively at some of the sites (e.g., chlorine sources, sulfate-bearing road dust, and different types of industrial emissions). These sources overall accounted for a small fraction of the total PM mass across the sampling locations (1 to 15%, on an annual average basis).

  17. Spatial and temporal variability of sources of ambient fine particular matter (PM2.5) in California

    Science.gov (United States)

    Hasheminassab, S.; Daher, N.; Saffari, A.; Wang, D.; Ostro, B. D.; Sioutas, C.

    2014-08-01

    To identify major sources of ambient fine particulate matter (PM2.5, dpSimi Valley, Bakersfield, Fresno, San Jose, and Sacramento. Between five to nine sources of fine PM were identified at each sampling site, several of which were common among multiple locations. Secondary aerosols, including secondary ammonium nitrate and ammonium sulfate, were the most abundant contributor to ambient PM2.5 at all sampling sites, except for San Jose, with an annual average cumulative contribution of 26 to 63%, across the state. On an annual average basis, vehicular emissions (including both diesel and gasoline vehicles) were the largest primary source of fine PM at all sampling sites in southern California (17-18% of total mass), whereas in Fresno and San Jose, biomass burning was the most dominant primary contributor to ambient PM2.5 (27 and 35% of total mass, respectively), in general agreement with the results of previous source apportionment studies in California. In Bakersfield and Sacramento, vehicular emissions and biomass burning displayed relatively equal annual contributions to ambient PM2.5 mass (12 and 25%, respectively). Other commonly identified sources at all sites included aged and fresh sea salt as well as soil, which contributed to 0.5-13%, 2-27%, and 1-19% of the total mass, respectively, across all sites and seasons. In addition, few minor sources were exclusively identified at some of the sites (e.g. chlorine sources, sulfate-bearing road dust, and different types of industrial emissions). These sources overall accounted for a small fraction of the total PM mass across the sampling locations (1 to 15%, on an annual average basis).

  18. Spatial/temporal variations and source apportionment of VOCs monitored at community scale in an urban area.

    Science.gov (United States)

    Yu, Chang Ho; Zhu, Xianlei; Fan, Zhi-hua

    2014-01-01

    This study aimed to characterize spatial/temporal variations of ambient volatile organic compounds (VOCs) using a community-scale monitoring approach and identify the main sources of concern in Paterson, NJ, an urban area with mixed sources of VOCs. VOC samples were simultaneously collected from three local source-dominated (i.e., commercial, industrial, and mobile) sites in Paterson and one background site in Chester, NJ (located ∼58 km southwest of Paterson). Samples were collected using the EPA TO-15 method from midnight to midnight, one in every sixth day over one year. Among the 60 analyzed VOCs, ten VOCs (acetylene, benzene, dichloromethane, ethylbenzene, methyl ethyl ketone, styrene, toluene, m,p-xylene, o-xylene, and p-dichlorobenzene) were selected to examine their spatial/temporal variations. All of the 10 VOCs in Paterson were significantly higher than the background site (pp-xylene, o-xylene, and p-dichlorobenzene measured at the commercial site were significantly higher than the industrial/mobile sites (pp-dichlorobenzene) were significantly different by season (pp<0.05). These results are consistent with literature data, indicating the impact of anthropogenic VOC sources on air pollution in Paterson. Positive Matrix Factorization (PMF) analysis was applied for 24-hour integrated VOC measurements in Paterson over one year and identified six contributing factors, including motor vehicle exhausts (20%), solvents uses (19%), industrial emissions (16%), mobile+stationery sources (12%), small shop emissions (11%), and others (22%). Additional locational analysis confirmed the identified sources were well matched with point sources located upwind in Paterson. The study demonstrated the community-scale monitoring approach can capture spatial variation of VOCs in an urban community with mixed VOC sources. It also provided robust data to identify major sources of concern in the community.

  19. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2014-12-01

    Full Text Available Trace element deposition from desert dust has important impacts on ocean primary productivity. In this study, emission inventories for 8 elements, which are primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si were determined based on a global mineral dataset and a soils dataset. Datasets of elemental fractions were used to drive the desert dust model in the Community Earth System Model (CESM in order to simulate the elemental concentrations of atmospheric dust. Spatial variability of mineral dust elemental fractions was evident on a global scale, particularly for Ca. Simulations of global variations in the Ca / Al ratio, which typically ranged from around 0.1 to 5.0 in soil sources, were consistent with observations, suggesting this ratio to be a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different that estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observational elemental aerosol concentration data from desert regions and dust events in non-dust regions, providing insights into uncertainties in the modeling approach. The ratios between modeled and observed elemental fractions ranged from 0.7 to 1.6 except for 3.4 and 3.5 for Mg and Mn, respectivly. Using the soil data base improved the correspondence of the spatial hetereogeneity in the modeling of several elements (Ca, Al and Fe compared to observations. Total and soluble dust associated element fluxes into different ocean basins and ice sheets regions have been estimated, based on the model results. Annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using mineral dataset were 0.28 Tg, 16.89 Gg, 1.32 Tg, 22.84 Gg, 0.068 Tg, and 0.15 Tg to global oceans and ice sheets.

  20. Spatial Context from Open and Online Processing (SCOOP: Geographic, Temporal, and Thematic Analysis of Online Information Sources

    Directory of Open Access Journals (Sweden)

    Colin Robertson

    2017-06-01

    Full Text Available The Internet is increasingly a source of data for geographic information systems, as more data becomes linked, available through application programing interfaces (APIs, and more tools become available for handling unstructured web data. While many web data extraction and structuring methods exist, there are few examples of comprehensive data processing and analysis systems that link together these tools for geographic analyses. This paper develops a general approach to the development of spatial information context from unstructured and informal web data sources through the joint analysis of the data’s thematic, spatial, and temporal properties. We explore the utility of this derived contextual information through a case study into maritime surveillance. Extraction and processing techniques such as toponym extraction, disambiguation, and temporal information extraction methods are used to construct a semi-structured maritime context database supporting global scale analysis. Geographic, temporal, and thematic content were analyzed, extracted and processed from a list of information sources. A geoweb interface is developed to allow user visualization of extracted information, as well as to support space-time database queries. Joint keyword clustering and spatial clustering methods are used to demonstrate extraction of documents that relate to real world events in official vessel information data. The quality of contextual geospatial information sources is evaluated in reference to known maritime anomalies obtained from authoritative sources. The feasibility of automated context extraction using the proposed framework and linkage to external data using standard clustering tools is demonstrated.

  1. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment—The Obvious Source “Ain’t Necessarily So”

    Directory of Open Access Journals (Sweden)

    Brian Gulson

    2016-02-01

    Full Text Available Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision 204Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS data presentations of the higher abundance isotopes 208Pb, 207Pb and 206Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town.

  2. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment--The Obvious Source "Ain't Necessarily So".

    Science.gov (United States)

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-02-22

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The