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Sample records for aged mineral dust

  1. Aging of mineral dust during transport from the Sahara into the Cape Verde area - results from airborne measurements during SAMUM

    NASA Astrophysics Data System (ADS)

    Weinzierl, B.; Sauer, D.; Esselborn, M.; Petzold, A.; Veira, A.; Rose, M.; Mund, S.; Wirth, M.; Ansmann, A.; Tesche, M.; Groß, S.; Freudenthaler, V.

    2012-04-01

    The Saharan Mineral Dust Experiment (SAMUM) was conducted to better understand the properties of fresh and aged mineral dust. Within SAMUM, two field missions were performed: SAMUM-1 (summer 2006, Morocco) focused on the chemical, microphysical, optical and radiative properties of fresh dust aerosol in the vertical column over the Sahara, while SAMUM-2 (winter 2008, Cape Verde) concentrated on the properties of aged dust and the mixing of mineral dust with biomass burning aerosol. During both field experiments, the DLR Falcon research aircraft was equipped with an extensive set of aerosol instruments for size, volatility, and absorption measurements, impactor sampling for chemical analyses and with a nadir-looking High Spectral Resolution Lidar (HSRL). In the Cape Verde area, we found a complex stratification with dust covering the altitude range below 2 km and tropical biomass burning layers aloft. We show that the aerosol type of individual aerosol layers can be classified based on depolarization and lidar ratios and, in addition, on in situ measured Ångström exponents of absorption åap. The dust layers had a geometrical depth of 1.3 ± 0.4 km and showed a median åap of 3.95. The median effective diameter Deff was 2.5 μm and the dust layers over Cape Verde yielded clear signals of aging: large particles were depleted due to gravitational settling and the accumulation mode diameter was shifted towards larger sizes as a result of coagulation. The tropical biomass layers had a depth of 2.0 ± 1.1 km and were characterized by a median åap of 1.34. They always contained a certain amount of large dust particles and showed a median Deff of 1.1 μm and a fine mode Deff,fine of 0.33. The dust and biomass burning layers had a median aerosol optical depth (AOD) of 0.23 and 0.09, respectively. The median contributions of the dust and biomass burning layers to the AOD of the total atmospheric column below 10 km were 75 and 37%, respectively. We present the properties of

  2. Mineral dust deposition in Western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Vincent, Julie; Laurent, Benoit; Bergmatti, Gilles; Losno, Rémi; Bon Nguyen, Elisabeth; Chevaillier, Servanne; Roulet, Pierre; Sauvage, Stéphane; Coddeville, Patrice; Ouboulmane, Noura; Siour, Guillaume; Tovar Sanchez, Antonio; Massanet, Ana; Morales Baquero, Rafael; Di Sarra, Giogio; Sferlazzo, Damiano; Dulac, François; Fornier, Michel; Coursier, Cyril

    2014-05-01

    North African deserts are the world's largest sources of atmospheric mineral dust produced by aeolian erosion. Saharan dust is frequently transported toward Europe over the Mediterranean basin. When deposited in oceanic areas, mineral dust can constitute a key input of nutrients bioavailable for the oceanic biosphere. For instance, Saharan dust deposited in the in the Mediterranean Sea can be a significant source of nutrient like Fe, P and N during summer and autumn. Our objective is to study the deposition Saharan mineral dust in the western Mediterranean basin and to improve how deposition processes are parameterized in 3D regional models. To quantify the deposition flux of Saharan dust in the western Mediterranean region a specific collector (CARAGA) to sample automatically the insoluble atmospheric particle deposition was developed (LISA-ICARE) and a network of CARAGA collectors have been set up. Since 2011, eight CARAGA are then deployed in Frioul, Casset, Montandon and Ersa in France, Mallorca and Granada in Spain, Lampedusa in Italia, and Medenine in Tunisia, along a South-North gradient of almost 2000km from the North African coast to the South of Europe. We observe 10 well identified dust Saharan deposition events at Lampedusa and 6 at Mallorca for a 1-yr sampling period. These dust events are sporadic and the South-North gradient of deposition intensity and frequency is observed (the highest dust mass sampled at the stations are : 2,66 g.m-2 at Lampedusa ; 0,54 g.m-2 at Majorque ; 0,33 g.m-2 at Frioul ; 0,16 g.m-2 at Casset). The ability of the CHIMERE model to reproduce the deposition measurements is tested. The mineral dust plumes simulated over the western Mediterranean basin are also compared to satellite observations (OMI, MODIS) and in-situ measurements performed during the ChArMEx campaign and in the AERONET stations.

  3. Predicting the Mineral Composition of Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Perez, C.; Miller, R. L.; Rodriguez, S.

    2012-12-01

    Models of the soil (''mineral'') dust aerosol cycle, embedded in climate and Earth system models, are essential tools for understanding the causal relationships and feedbacks between dust and climate. Many soil dust schemes in Earth system models use a simplified representation of soil dust aerosols, where the soil dust is distinguished by size bins or size distribution modes, with a globally uniform representation of the mineralogical composition of the particles. Although models with such a simplified assumption about the properties of soil dust particles have already significantly contributed to the understanding of the role of soil dust aerosols in climate, this is a limitation for a number of reasons: 1. The response of clouds and the large-scale circulation depends on the radiative properties like the single scattering albedo, which should vary with the mineral composition of the source region; 2. Chemical processes at the surface of the soil dust particles that form sulfate and nitrate coatings depend on the dust mineral composition; 3. The availability of soil dust minerals as cloud condensation nuclei depends on their hygroscopicity, which in turn depends on the mineral composition; 4. Fertilization of phytoplankton with soluble iron, a process that influences ocean carbon uptake, depends upon mineral types. We present a new version of the soil dust scheme in the NASA GISS Earth System ModelE, which takes into account the mineral composition of the soil dust particles. Soil dust aerosols are represented as a mixture of externally and internally mixed minerals, such as Illite, Kaolinite, Smectite, Calcite, Iron(hydr)oxide, Quartz, Feldspar, and Gypsum, as well as aggregates between Iron(hydr)oxide and each of the minerals. We test two approaches to constrain the mineral composition of the soil dust particles against data from measurements published in literature as well as measurements from Izaña (Tenerife). The comparison between modeled and measured data

  4. Immersion freezing on mineral dust particles

    NASA Astrophysics Data System (ADS)

    Zolles, Tobias; Grothe, Hinrich; Pummer, Bernhard

    2013-04-01

    Mineral dust is considered to play a major role in ice cloud nucleation in the troposphere. More than 1.000 Tg of mineral dust are aerosolized from the ground every year, 1-10% of these reach the upper troposphere [1]. At an altitude of about 8 km ice residual particle analysis has shown that about 50% of all ice nuclei (IN) are mineral dust[2]. In principle, natural occurring dusts may either be IN-active themselves or are carriers of organic and/or biological IN. Up to now the ice nucleation, i.e. cloud glaciation, has not been quantized. However, different authors report a high IN-activity for many mineral dust samples, although a systematic comparison between different minerals is still missing. Therefore, we studied selected mineral dust samples which were characterized by X-ray diffraction, FTIR spectroscopy, and scanning electron microscopy before use. Oil immersion measurements were performed on the most common minerals, clay materials and volcanic ash. The median freezing temperatures range from -21°C up to homogenous freezing at 38°C. Even though quite a few dust samples show a reasonable high IN-activity, their median freezing temperatures are low compared to biological samples [3, 4]. Furthermore, heat treatment of the dusts was applied in order to decompose and to denaturize organic and/or biological surfactants. Finally, some dust samples had a high loss of activity and thus were subjects of further experiments. These mineral dust particles were suspended in water and after an incubation time were removed. In some cases the washing water had become IN-active, but lost its activity after enzymatic treatment. The observed high IN-activity can thus be explained by adsorbed biological materials. The results suggest that some mineral dusts are IN-active, and if it is not intrinsic they may even enhance IN-activity of organic and biological IN if these are adsorbed on the dust particle surface. A relatively high IN-activity of the pure mineral dusts was

  5. Remote Sensing of Mineral Dust Sources (Invited)

    NASA Astrophysics Data System (ADS)

    Sprigg, W. A.; Morain, S. A.

    2009-12-01

    Thirty-four percent of Earth's land surface is arid, home to two billion people routinely exposed to airborne dust and increased risk of cardiovascular and respiratory disease. The NASA-supported Public Health Applications in Remote Sensing project has improved the process of simulating and predicting when and where dust storms will occur and the consequent particulate air quality. Partnerships with state public health offices test model products for epidemiological and health surveillance applications. The key to significant improvement in simulations, forecasts and their use has been identifying and monitoring mineral dust sources via satellite based sensors.

  6. Hygroscopic properties of large aerosol particles using the example of aged Saharan mineral dust - a semi-automated electron microscopy approach

    NASA Astrophysics Data System (ADS)

    Hartmann, Markus; Heim, Lars-Oliver; Ebert, Martin; Weinbruch, Stephan; Kandler, Konrad

    2015-04-01

    Hygroscopic properties of large aerosol particles using the example of aged Saharan mineral dust - a semi-automated electron microscopy approach Markus Hartmann(1), Lars-Oliver Heim(2), Martin Ebert(1), Stephan Weinbruch(1), Konrad Kandler(1) The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) took place at Barbados from June 10 to July 15 2013. During this period, dust was frequently transported from Africa across the Atlantic Ocean toward the Caribbean. In this study, we investigate the atmospheric aging of the dust aerosol based on its hygroscopicity. Aerosol samples were collected ground-based at Ragged Point (13°9'54.4"N, 59°25'55.7"W) with a single round jet cascade impactor on nickel-substrates. The particles from the stage with a 50% efficiency cutoff size of 1 µm were analyzed with an Environmental Scanning Electron Microscope (ESEM) equipped with an energy-dispersive X-ray detector (EDX) and a cooling stage. In an initial automated run, information on particle size and chemical composition for elements heavier than carbon were gathered. Afterwards, electron microscope images of the same sample areas as before were taken during a stepwise increase of relative humidities (between 50 % and 92%), so that the hygroscopic growth of the droplets could be directly observed. The observed hygroscopic growth can be correlated to the chemical composition of the respective particles. For the automated analysis of several hundred images of droplets an image processing algorithm in Python was developed. The algorithm is based on histogram equalization and watershed segmentation. Since SEM images can only deliver two-dimensional information, but the hygroscopic growth factor usually refers to the volume of a drop, Atomic Force Microscopy (AFM) was used to derive an empirical function for the drop volume depending on the apparent drop diameter in the electron images. Aside from the mineral dust, composed of mostly silicates and

  7. Simulations of Mineral Dust Content With CHIMERE-Dust Model

    NASA Astrophysics Data System (ADS)

    Schmechtig, C.; Marticorena, B.; Menut, L.; Bergametti, G.

    2006-12-01

    Simulations of the mineral dust cycle have been performed whith CHIMERE-Dust model over a domain that includes North Africa, the Mediterranean basin and the North Tropical Atlantic Ocean (10S-60N and 90W-90E) with a 1°x1° resolution using the ECMWF (European Center for Medium-Range Weather Forecasts) meteorological fields for two years, 2000 and 2001. As a validation, we compare the simulated dust concentration fields with photometric data from the AERONET network. From the comparisons between the simulated and measured aerosol optical depth for several stations of the Mediterranean basin, the model appears to reproduce correctly the intensity and occurrences of the dust events. Over Western Africa, the results are not as satisfying since some of the most intense dust events observed on the continent and downwind are not captured by the model. In addition, the simulated events are generally underestimated compared to the measured ones. It appears that these differences in the model performances are connected to the origin of the dust plumes. For example, dust plumes coming from Libya are well simulated while dust plumes originating from the Bodélé depression not as frequent as intense as the observations suggest. Soil properties in these two regions are comparable and typical of very erodible surfaces. We thus focused on the comparison between the ECMWF 10m wind speed fields and 10m wind speed measured at the meteorological stations located in both areas. We noticed that over Libya, the measured and ECMWF 10m wind speed are in very good agreement, while the meteorological model does not reproduce the extrema of the measured wind speed in the Bodélé depression. We found that a crude empirical correction of the 10m wind field in the Bodélé Depression significantly improve the simulations in terms of occurrence and of intensity.

  8. Mineral dust transport toward Hurricane Helene (2006)

    NASA Astrophysics Data System (ADS)

    Schwendike, Juliane; Jones, Sarah C.; Vogel, Bernhard; Vogel, Heike

    2016-05-01

    This study investigates the transport of mineral dust from its source regions in West Africa toward the developing tropical cyclone Helene (2006) and diagnoses the resulting properties of the air influencing the tropical cyclonegenesis. The model system COSMO-ART (Consortium for Small-Scale Modelling-Aerosols and Reactive Trace gases) in which the emission and transport of mineral dust as well as the radiation feedback are taken into account, was used. The emission of mineral dust between 9 and 14 September 2006 occurred in association with the relatively strong monsoon flow and northeasterly trade winds, with gust fronts of convective systems over land, and with the Atlantic inflow. Additionally, increased surface wind speed was linked to orographical effects at the Algerian Mountains, Atlas Mountains, and the Hoggar. The dust, as part of the Saharan air layer, is transported at low levels by the monsoon flow, the Harmattan, the northeasterly trade winds, and the monsoon trough, and is transported upward in the convergence zone between Harmattan and monsoon flow, in the baroclinic zone along the West African coastline, and by convection. At around 700 hPa the dust is transported by the African easterly jet. Dry and dust-free air is found to the north-northwest of the developing tropical depression due to descent in an anticyclone. Based on the model data, it was possible to distinguish between dry (from the anticyclone), dry and dusty (from the Harmattan and northeasterly trade winds), and dusty and moist air (from the monsoon flow and in the tropical depression due to convection).

  9. Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation.

    PubMed

    Tang, Mingjin; Cziczo, Daniel J; Grassian, Vicki H

    2016-04-13

    Mineral dust aerosol is one of the major types of aerosol present in the troposphere. The molecular level interactions of water vapor with mineral dust are of global significance. Hygroscopicity, light scattering and absorption, heterogneous reactivity and the ability to form clouds are all related to water-dust interactions. In this review article, experimental techniques to probe water interactions with dust and theoretical frameworks to understand these interactions are discussed. A comprehensive overview of laboratory studies of water adsorption, hygroscopicity, cloud condensation, and ice nucleation of fresh and atmspherically aged mineral dust particles is provided. Finally, we relate laboratory studies and theoretical simulations that provide fundemental insights into these processes on the molecular level with field measurements that illustrate the atmospheric significance of these processes. Overall, the details of water interactions with mineral dust are covered from multiple perspectives in this review article. PMID:27015126

  10. Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation.

    PubMed

    Tang, Mingjin; Cziczo, Daniel J; Grassian, Vicki H

    2016-04-13

    Mineral dust aerosol is one of the major types of aerosol present in the troposphere. The molecular level interactions of water vapor with mineral dust are of global significance. Hygroscopicity, light scattering and absorption, heterogneous reactivity and the ability to form clouds are all related to water-dust interactions. In this review article, experimental techniques to probe water interactions with dust and theoretical frameworks to understand these interactions are discussed. A comprehensive overview of laboratory studies of water adsorption, hygroscopicity, cloud condensation, and ice nucleation of fresh and atmspherically aged mineral dust particles is provided. Finally, we relate laboratory studies and theoretical simulations that provide fundemental insights into these processes on the molecular level with field measurements that illustrate the atmospheric significance of these processes. Overall, the details of water interactions with mineral dust are covered from multiple perspectives in this review article.

  11. Exposure to mineral sands dust particles

    NASA Astrophysics Data System (ADS)

    Dias da Cunha, K.; Barros Leite, C. V.; Zays, Z.

    2004-06-01

    The aim of this study is to characterize the airborne particles in a Brazilian region with high concentration of mineral sands (Buena village). In this study proton induced X-ray emission (PIXE), plasma desorption mass spectrometry and alpha spectrometry were used for analyses of airborne particles. The analyses of aerosol samples and lichen samples show that the inhabitants of the Buena village are exposed to airborne particles in the fine fraction of aerosols. The main anthropogenic sources of particles are the mineral sands processing plant and truck traffic, and natural sources as the sea, soil and the swamp. The results from the lichen samples show that at least during the last 15 years the inhabitants of the village have been exposed to monazite particles. The results from aerosols and lichens samples also suggested that the swamp is a source of 226Ra and 210Pb bearing particles besides the monazite dust.

  12. Evidence of Mineral Dust Altering Cloud Microphysics and Precipitation

    NASA Technical Reports Server (NTRS)

    Min, Qilong; Li, Rui; Lin, Bing; Joseph, Everette; Wang, Shuyu; Hu, Yongxiang; Morris, Vernon; Chang, F.

    2008-01-01

    Multi-platform and multi-sensor observations are employed to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective systems. It is clearly evident that for a given convection strength,small hydrometeors were more prevalent in the stratiform rain regions with dust than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust sector, particularly at altitudes where heterogeneous nucleation process of mineral dust prevails, further supports the observed changes of precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the precipitation size spectrum from heavy precipitation to light precipitation and ultimately suppressing precipitation.

  13. Understanding mineral dusts from the Middle East

    NASA Astrophysics Data System (ADS)

    Engelbrecht, J. P.; McDonald, E.; Gillies, J. A.; Jayanty, J.; Casuccio, G.; Gertler, A.

    2012-12-01

    The purpose of the program was to provide scientifically founded information on the chemical and physical properties of airborne mineral dust collected during a period of approximately one year, largely in 2006, at Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (Northern, Central, Coastal, and Southern regions). To fully understand mineral dusts, their chemical and physical properties as well as mineralogical interrelationships were accurately established. Three collocated low volume particulate samplers, one each for the total suspended (TSP), less than 10 μm in aerodynamic diameter (PM10), and less than 2.5 μm in aerodynamic diameter (PM2.5) particulate matter were deployed at each of the 15 sites, operating on a "1 in 6 day" sampling schedule. A total of 3,136 filter samples were collected on a 1-in-6 day schedule, along with one-time bulk soil samples, at each of the 15 sites. Sample media included Teflon® membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore® filters for individual particle analysis by Scanning Electron Microscopy (SEM). The provisional study of the data revealed three broad air pollution sources: geological dust, smoke from burn pits, and until now unidentified lead-zinc smelters and battery-processing facilities. SEM results and secondary electron imagery show that quartz and other silicate minerals and, to a lesser extent, dolomite and calcite particles are coated by a thin Si-Al-Mg layer, probably the clay minerals palygorskite and/or montmorillonite/illite. Positive Matrix Factorization (PMF) was performed on aerosol samples collected at six military sites in Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, and Al Asad). PMF results reflect chemical differences amongst sources impacting at individual sites, further complicated by the regional geomorphology and meteorology. Sampling sites are seldom impacted by one source at

  14. 76 FR 12648 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-08

    ...' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors AGENCY: Mine Safety and... Continuous Personal Dust Monitors. The proposed rule would improve health protections for coal miners by... Occupational Exposure to Respirable Coal Mine Dust, the National Institute for Occupational Safety and...

  15. 75 FR 69617 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... addressing Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors. The proposed rule was published on October 19, 2010 (75 FR 64412) and is available on MSHA's Web...' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors AGENCY: Mine Safety...

  16. Mineral dust transport in the Arctic modelled with FLEXPART

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Aeolian transport of mineral dust is suggested to play an important role in many processes. For instance, mineral aerosols affect the radiation balance of the atmosphere, and mineral deposits influence ice sheet mass balances and terrestrial and ocean ecosystems. While many efforts have been done to model global dust transport, relatively little attention has been given to mineral dust in the Arctic. Even though this region is more remote from the world's major dust sources and dust concentrations may be lower than elsewhere, effects of mineral dust on for instance the radiation balance can be highly relevant. Furthermore, there are substantial local sources of dust in or close to the Arctic (e.g., in Iceland), whose impact on Arctic dust concentrations has not been studied in detail. We therefore aim to estimate contributions of different source regions to mineral dust in the Arctic. We have developed a dust mobilization routine in combination with the Lagrangian dispersion model FLEXPART to make such estimates. The lack of details on soil properties in many areas requires a simple routine for global simulations. However, we have paid special attention to the dust sources on Iceland. The mobilization routine does account for topography, snow cover and soil moisture effects, in addition to meteorological parameters. FLEXPART, driven with operational meteorological data from European Centre for Medium-Range Weather Forecasts, was used to do a three-year global dust simulation for the years 2010 to 2012. We assess the model performance in terms of surface concentration and deposition at several locations spread over the globe. We will discuss how deposition and dust load patterns in the Arctic change throughout seasons based on the source of the dust. Important source regions for mineral dust found in the Arctic are not only the major desert areas, such as the Sahara, but also local bare-soil regions. From our model results, it appears that total dust load in the

  17. Mineral dusts and radon in uranium mines

    SciTech Connect

    Abelson, P.H.

    1991-11-08

    The Environmental Protection Agency (EPA) continues to assert that radon is a major cause of lung cancer in this country. EPA is fostering a radon program that could entail huge financial and emotional costs while yielding negligible benefits to public health. Justification for the program was the occurrence of lung cancer in men exposed to huge amounts of radon, mineral dusts, and other lung irritants in uranium mines on the Colorado Plateau. Lung cancer has been reported in about 356 cigarette smokers and in about 25 nonsmokers. During the era of high radon levels, monitoring was sporadic. Conditions in only a small fraction of the mines were measured, and that on a few separate occasions. Later, cumulative exposure to radon was calculated on the basis of measurements involving only a tiny fraction of the miners. Some were exposed to more than 15,000 pCi/liter of radon and its products. The level in the average home is about 1.5 pCi/liter. In making extrapolations from mine to home, the assumption is made that residents are in their dwellings most of the time and that miners spend only 170 hours a month in the mine. Two major questionable assumptions are involved in extrapolations from high doses of radon in the mines to low doses in homes. One is that no threshold is involved; that is, that humans have no remediation mechanism for {alpha} particle damages. There is evidence to the contrary. The most unrealistic assumption is that heavy exposure to silica has no effect on inducing lung cancer. Many studies have shown that silica dust causes lung cancer in animals. Exposure of human culture cells to silica has resulted in formation of neoplastic tissue. EPA has no solid evidence that exposures to 4 pCi/liter of radon causes lung cancer in either smokers or nonsmokers. Indeed, there is abundant evidence to the contrary in the fact that in states with high levels of radon, inhabitants have less lung cancer than those in states with low levels.

  18. New Manganese Silicide Mineral Phase in an Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Palma, R. L.; Pepin, R. O.; Kloeck, W.; Zolensky, M. E.; Messenger, S.

    2008-01-01

    Comet 26P/Grigg-Skjellerup was identified as a source of an Earth-crossing dust stream with low Earth-encounter velocities, with peak anticipated fluxes during April in 2003 and 2004 [1]. In response to this prediction, NASA performed dedicated stratospheric dust collections using high altitude aircraft to target potential interplanetary dust particles (IDPs) from this comet stream in April 2003. Several IDPs from this collection have shown unusually low noble gas abundances [2] consistent with the predicted short space exposure ages of Grigg-Skjellerup dust particles [1]. High abundances of large D enrichments [3] and presolar grains [4] in IDPs from this collection are also consistent with an origin from the comet Grigg-Skjellerup. Here we report a new mineral from one of the cluster IDPs of the "Grigg-Skjellerup" collection, L2055. Our report focuses on an unusual manganese-iron-chromium silicide phase that, to our knowledge, has not been observed previously in nature. This unique phase may also shed light on the genesis of the enigmatic low-Fe,Mn-enriched (LIME) olivine that has been previously reported in IDPs and meteorites [5].

  19. 76 FR 25277 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ... FR 64412), MSHA published a proposed rule, Lowering Miners' Exposure to Respirable Coal Mine Dust... the proposed rule. The proposal was published on October 19, 2010 (75 FR 64412). DATES: All comments...' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors AGENCY: Mine Safety...

  20. Comparison of the mixing state of long-range transported Asian and African mineral dust

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Elizabeth; Ault, Andrew P.; Zauscher, Melanie D.; Mayol-Bracero, Olga L.; Prather, Kimberly A.

    2015-08-01

    Mineral dust from arid regions represents the second largest global source of aerosols to the atmosphere. Dust strongly impacts the radiative balance of the earth's atmosphere by directly scattering solar radiation and acting as nuclei for the formation of liquid droplets and ice nuclei within clouds. The climate effects of mineral dust aerosols are poorly understood, however, due to their complex chemical and physical properties, which continuously evolve during atmospheric transport. This work focuses on characterizing atmospheric mineral dust from the two largest global dust sources: the Sahara Desert in Africa and the Gobi and Taklamakan Deserts in Asia. Measurements of individual aerosol particle size and chemical mixing state were made at El Yunque National Forest, Puerto Rico, downwind of the Sahara Desert, and Gosan, South Korea, downwind of the Gobi and Taklamakan Deserts. In general, the chemical characterization of the individual dust particles detected at these two sites reflected the dominant mineralogy of the source regions; aluminosilicate-rich dust was more common at El Yunque (∼91% of El Yunque dust particles vs. ∼69% of Gosan dust particles) and calcium-rich dust was more common at Gosan (∼22% of Gosan dust particles vs. ∼2% of El Yunque dust particles). Furthermore, dust particles from Africa and Asia were subjected to different transport conditions and atmospheric processing; African dust showed evidence of cloud processing, while Asian dust was modified via heterogeneous chemistry and direct condensation of secondary species. A larger fraction of dust detected at El Yunque contained the cloud-processing marker oxalate ion compared to dust detected at Gosan (∼20% vs ∼9%). Additionally, nearly 100% of dust detected at Gosan contained nitrate, showing it was aged via heterogeneous reactions with nitric acid, compared to only ∼60% of African dust. Information on the distinct differences in the chemical composition of mineral dust

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

    USGS Publications Warehouse

    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

  2. Effects of mineral dust on global atmospheric nitrate concentrations

    NASA Astrophysics Data System (ADS)

    Karydis, V. A.; Tsimpidi, A. P.; Pozzer, A.; Astitha, M.; Lelieveld, J.

    2016-02-01

    This study assesses the chemical composition and global aerosol load of the major inorganic aerosol components, focusing on mineral dust and aerosol nitrate. The mineral dust aerosol components (i.e., Ca2+, Mg2+, K+, Na+) and their emissions are included in the ECHAM5/MESSy Atmospheric Chemistry model (EMAC). Gas/aerosol partitioning is simulated using the ISORROPIA-II thermodynamic equilibrium model that considers K+, Ca2+, Mg2+, NH4+, Na+, SO42-, NO3-, Cl-, and H2O aerosol components. Emissions of mineral dust are calculated online by taking into account the soil particle size distribution and chemical composition of different deserts worldwide. Presence of metallic ions can substantially affect the nitrate partitioning into the aerosol phase due to thermodynamic interactions. The model simulates highest fine aerosol nitrate concentration over urban and industrialized areas (1-3 µg m-3), while coarse aerosol nitrate is highest close to deserts (1-4 µg m-3). The influence of mineral dust on nitrate formation extends across southern Europe, western USA, and northeastern China. The tropospheric burden of aerosol nitrate increases by 44 % when considering interactions of nitrate with mineral dust. The calculated global average nitrate aerosol concentration near the surface increases by 36 %, while the coarse- and fine-mode concentrations of nitrate increase by 53 and 21 %, respectively. Other inorganic aerosol components are affected by reactive dust components as well (e.g., the tropospheric burden of chloride increases by 9 %, ammonium decreases by 41 %, and sulfate increases by 7 %). Sensitivity tests show that nitrate aerosol is most sensitive to the chemical composition of the emitted mineral dust, followed by the soil size distribution of dust particles, the magnitude of the mineral dust emissions, and the aerosol state assumption.

  3. Size distribution and optical properties of African mineral dust after intercontinental transport

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Formenti, Paola; Desboeufs, Karine; Chevaillier, Servanne; Triquet, Sylvain; Maillé, Michel; Cazaunau, Mathieu; Laurent, Benoit; Mayol-Bracero, Olga L.; Vallejo, Pamela; Quiñones, Mariana; Gutierrez-Molina, Ian E.; Cassola, Federico; Prati, Paolo; Andrews, Elisabeth; Ogren, John

    2016-06-01

    The transatlantic transport of mineral dust from Africa is a persistent atmospheric phenomenon, clue for understanding the impacts of dust at the global scale. As part of the DUST Aging and Transport from Africa to the Caribbean (Dust-ATTACk) intensive field campaign, the size distribution and optical properties of mineral dust were measured in June-July 2012 on the east coast of Puerto Rico, more than 5000 km from the west coast of Africa. During the recorded dust events, the PM10 (particulate matter 10 micrometers or less in diameter) concentrations increased from 20 to 70 µg m-3. Remote sensing observations and modeling analysis were used to identify the main source regions, which were found in the Western Sahara, Mauritania, Algeria, Niger, and Mali. The microphysical and optical properties of the dust plumes were almost independent of origin. The size distribution of mineral dust after long-range transport may have modal diameters similar to those on the eastern side of the Atlantic short time after emission, possibly depending on height of transport. Additional submicron particles of anthropogenic absorbing aerosols (likely from regional marine traffic activities) can be mixed within the dust plumes, without affecting in a significant way the PM10 absorption properties of dust observed in Puerto Rico. The Dust-ATTACk experimental data set may be useful for modeling the direct radiative effect of dust. For accurate representation of dust optical properties over the Atlantic remote marine region, we recommend mass extinction efficiency (MEE) and single-scattering albedo values in the range 1.1-1.5 m2 g-1 and 0.97-0.98, respectively, for visible wavelengths.

  4. New directions: Mineral dust and ozone - Heterogeneous chemistry

    NASA Astrophysics Data System (ADS)

    Ramachandran, S.

    2015-04-01

    Aerosols, the tiny solid or liquid particles suspended in air and produced from natural sources and anthropogenic activities, continue to contribute the largest uncertainty to radiative forcing (IPCC, 2013). Aerosol particles give rise to radiative forcing directly through scattering and absorption of solar and infrared radiation in the atmosphere. Aerosols also give rise to indirect radiative forcing by modifying the cloud optical properties and lifetimes. Among the aerosol species mineral dust and black carbon cause a warming (positive forcing) while sulphate and sea salt cause a cooling (negative forcing) of the Earth-atmosphere system. In tropics and sub-tropics mineral dust is a major contributor to aerosol loading and optical thickness. The global source strength of dust aerosol varies significantly on spatial and temporal scales. The source regions of dust are mainly deserts, dry lake beds, and semi-arid regions, in addition to drier regions where vegetation has been reduced or soil surfaces that are disturbed by man made activities. Anthropogenic activities mainly related to agriculture such as harvesting, ploughing, overgrazing, and cement production and transport also produce mineral dust. An estimated 2500 terragram (Tg, 1012 g) of mineral dust is emitted into the atmosphere per year, and dominates the aerosol mass over continental regions in south Asia and China accounting for ∼35% of the total aerosol mass (IPCC, 2013). In India, dust is prevalent throughout the north and western India during the year and peaks during premonsoon season.

  5. Does the long-range transport of African mineral dust across the Atlantic enhance their hygroscopicity?

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Caquineau, Sandrine; Desboeufs, Karine; Laurent, Benoit; Quiñones Rosado, Mariana; Vallejo, Pamela; Mayol-Bracero, Olga; Formenti, Paola

    2015-04-01

    Influence of mineral dust on radiation balance is largely dependent on their ability to interact with water. While fresh mineral dusts are highly hydrophobic, various transformation processes (coagulation, heterogeneous chemical reaction) can modify the dust physical and chemical properties during long-range transport, which, in turn, can change the dust hygroscopic properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of dust hygroscopic properties, and their temporal evolution during long-range transport. We present the first direct surface measurements of the hygroscopicity of Saharan dust after long-range transport over the Atlantic Ocean, their relationship with chemical composition, their influence on particle size and shape and implications for optical properties. Particles were collected during the DUST Aging and TransporT from Africa to the Caribbean (Dust-AttaCk) campaign at the Cape San Juan Puerto Rico station in June-July 2012. Environmental scanning electron microscopy (ESEM) was used to analyze the size, shape, chemical composition and hygroscopic properties of individual particles. At different levels of concentrations in summertime, the coarse mode of atmospheric aerosols in Puerto Rico is dominated by Saharan mineral dust. Most of aged dust particles survived atmospheric transport intact with no observed internal mixture with other species and did not show hygroscopic growth up to 94% relative humidity. This is certainly due to the fact that in summertime dust is mostly transported above the marine boundary layer. A minor portion of mineral dust (approximately 19-28% by number) were involved in atmospheric heterogeneous reactions with acidic gases (likely SO2 and HCl) and sea salt aggregation. While sulfate- and chloride-coated dust remained extremely hydrophobic, dust particles in internal mixing with NaCl underwent profound changes in their hygroscopicity, therefore in size and shape. We

  6. Heterogeneous uptake of nitrogen dioxide on Chinese mineral dust.

    PubMed

    Zhou, Li; Wang, Weigang; Hou, Siqi; Tong, Shengrui; Ge, Maofa

    2015-12-01

    Mineral dust is one of the major aerosols in the atmosphere. To assess its impact on trace atmospheric gases, in this work we present a laboratory study of the effect of temperature on the heterogeneous reaction of NO2 on the surface of ambient Chinese dust over the temperature range from 258 to 313K. The results suggest that nitrogen dioxide could mainly be adsorbed on these types of Chinese mineral dust reversibly with little temperature dependence. Similar to a previous study on NO2 uptake on mineral aerosols, the uptake coefficients are mainly on the order of 10(-6) for the Chinese dust, when BET areas are taken into account. HONO was observed as a product, and its formation and decomposition on Chinese mineral dust during the uptake processes were also studied. The complete dataset from this study was compiled with previous literature determinations. Atmospheric implications of the heterogeneous reaction between NO2 and mineral dust are also discussed, in an effort to understand this important heterogeneous process.

  7. Trans boundary transport of pollutants by atmospheric mineral dust.

    PubMed

    Erel, Yigal; Dayan, Uri; Rabi, Reut; Rudich, Yinon; Stein, Mordechai

    2006-05-01

    The transport of anthropogenic pollution by desert dust in the Eastern Mediterranean region was studied by analyzing major and trace element composition, organic species, and Pb isotope ratios in suspended dust samples collected in Jerusalem, Israel. Dust storms in this region are associated with four distinct synoptic conditions (Red Sea Trough (RS), Eastern High (EH), Sharav Cyclone (SC), and Cold Depression (Cyprus low, CD)) that carry dust mostly from North African (SC, CD, EH) and Arabian and Syrian (RS, EH) deserts. Substantial contamination of dust particles by Pb, Cu, Zn, and Ni is observed, while other elements (Na, Ca, Mg, Mn, Sr, Rb, REE, U, and Th) display natural concentrations. Sequential extraction of the abovementioned elements from the dust samples shows that the carbonate and sorbed fractions contain most of the pollution, yet the Al-silicate fraction is also contaminated, implying that soils and sediments in the source terrains of the dust are already polluted. We identified the pollutant sources by using Pb isotopes. It appears that before the beginning of the dust storm, the pollutants in the collected samples are dominated by local sources but with the arrival of dust from North Africa, the proportion of foreign pollutants increases. Organic pollutants exhibit behavior similar and complementary to that of the inorganic tracers, attesting to the importance of anthropogenic-pollutant addition en route of the dust from its remote sources. Pollution of suspended dust is observed under all synoptic conditions, yet it appears that easterly winds carry higher proportions of local pollution and westerly winds carry pollution emitted in the Cairo basin. Therefore, pollution transport by mineral dust should be accounted for in environmental models and in assessing the health-related effects of mineral dust.

  8. Interactions Between Mineral Dust, Climate, and Ocean Ecosystems

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; Grassian, Vicki H.; Miller, Ron L.

    2010-01-01

    Over the past decade, technological improvements in the chemical and physical characterization of dust have provided insights into a number of phenomena that were previously unknown or poorly understood. In addition, models are now incorporating a wider range of physical processes, which will allow us to better quantify the climatic and ecological impacts of dust. For example, some models include the effect of dust on oceanic photosynthesis and thus on atmospheric CO 2 (Friedlingstein et al. 2006). The impact of long-range dust transport, with its multiple forcings and feedbacks, is a relatively new and complex area of research, where input from several disciplines is needed. So far, many of these effects have only been parameterized in models in very simple terms. For example, the representation of dust sources remains a major uncertainty in dust modeling and estimates of the global mass of airborne dust. This is a problem where Earth scientists could make an important contribution, by working with climate scientists to determine the type of environments in which easily erodible soil particles might have accumulated over time. Geologists could also help to identify the predominant mineralogical composition of dust sources, which is crucial for calculating the radiative and chemical effects of dust but is currently known for only a few regions. Understanding how climate and geological processes control source extent and characterizing the mineral content of airborne dust are two of the fascinating challenges in future dust research.

  9. Clinically important respiratory effects of dust exposure and smoking in British coal miners

    SciTech Connect

    Marine, W.M.; Gurr, D.; Jacobsen, M.

    1988-01-01

    A unique data set of 3380 British coal miners has been reanalyzed with major focus on nonpneumoconiotic respiratory conditions. The aim was to assess the independent contribution of smoking and exposure to respirable dust to clinically significant measures of respiratory dysfunction. Exposure to coal-mine dust was monitored over a 10-yr period. Medical surveys provided estimates of prior dust exposure and recorded respiratory symptoms. Each man's FEV1 was compared with the level predicted for his age and height by an internally derived prediction equation for FEV1. Four respiratory indices were considered at the end of the 10-yr period: FEV1 less than 80%, chronic bronchitis, chronic bronchitis with FEV1 less than 80%, and FEV1 less than 65%. Results were uniformly incorporated into logistic regression equations for each condition. The equations include coefficients for age, dust, and when indicated, an interaction term for age and dust. Dust-related increases in prevalence of each of the 4 conditions were statistically significant and were similar for smokers and nonsmokers at the mean age (47 yr). There was no evidence that smoking potentiates the effect of exposure to dust. Estimates of prevalences at the mean age of all 4 measures of respiratory dysfunction were greater in smokers. At intermediate and high dust exposure the prevalence of the 4 conditions in nonsmokers approached the prevalence in smokers at hypothetically zero dust exposure. Both smoking and dust exposure can cause clinically important respiratory dysfunction and their separate contributions to obstructive airway disease in coal miners appear to be additive.

  10. Kinetics of Heterogeneous Reaction of Sulfur Dioxide on Authentic Mineral Dust: Effects of Relative Humidity and Hydrogen Peroxide.

    PubMed

    Huang, Liubin; Zhao, Yue; Li, Huan; Chen, Zhongming

    2015-09-15

    Heterogeneous reaction of SO2 on mineral dust seems to be an important sink for SO2. However, kinetic data about this reaction on authentic mineral dust are scarce and are mainly limited to low relative humidity (RH) conditions. In addition, little is known about the role of hydrogen peroxide (H2O2) in this reaction. Here, we investigated the uptake kinetics of SO2 on three authentic mineral dusts (i.e., Asian mineral dust (AMD), Tengger desert dust (TDD), and Arizona test dust (ATD)) in the absence and presence of H2O2 at different RHs using a filter-based flow reactor, and applied a parameter (effectiveness factor) to the estimation of the effective surface area of particles for the calculation of the corrected uptake coefficient (γc). We found that with increasing RH, the γc decreases on AMD particles, but increases on ATD and TDD particles. This discrepancy is probably due to the different mineralogy compositions and aging extents of these dust samples. Furthermore, the presence of H2O2 can promote the uptake of SO2 on mineral dust at different RHs. The probable explanations are that H2O2 rapidly reacts with SO2 on mineral dust in the presence of adsorbed water, and OH radicals, which can be produced from the heterogeneous decomposition of H2O2 on the mineral dust, immediately react with adsorbed SO2 as well. Our results suggest that the removal of SO2 via the heterogeneous reaction on mineral dust is an important sink for SO2 and has the potential to alter the physicochemical properties (e.g., ice nucleation ability) of mineral dust particles in the atmosphere. PMID:26281003

  11. Kinetics of Heterogeneous Reaction of Sulfur Dioxide on Authentic Mineral Dust: Effects of Relative Humidity and Hydrogen Peroxide.

    PubMed

    Huang, Liubin; Zhao, Yue; Li, Huan; Chen, Zhongming

    2015-09-15

    Heterogeneous reaction of SO2 on mineral dust seems to be an important sink for SO2. However, kinetic data about this reaction on authentic mineral dust are scarce and are mainly limited to low relative humidity (RH) conditions. In addition, little is known about the role of hydrogen peroxide (H2O2) in this reaction. Here, we investigated the uptake kinetics of SO2 on three authentic mineral dusts (i.e., Asian mineral dust (AMD), Tengger desert dust (TDD), and Arizona test dust (ATD)) in the absence and presence of H2O2 at different RHs using a filter-based flow reactor, and applied a parameter (effectiveness factor) to the estimation of the effective surface area of particles for the calculation of the corrected uptake coefficient (γc). We found that with increasing RH, the γc decreases on AMD particles, but increases on ATD and TDD particles. This discrepancy is probably due to the different mineralogy compositions and aging extents of these dust samples. Furthermore, the presence of H2O2 can promote the uptake of SO2 on mineral dust at different RHs. The probable explanations are that H2O2 rapidly reacts with SO2 on mineral dust in the presence of adsorbed water, and OH radicals, which can be produced from the heterogeneous decomposition of H2O2 on the mineral dust, immediately react with adsorbed SO2 as well. Our results suggest that the removal of SO2 via the heterogeneous reaction on mineral dust is an important sink for SO2 and has the potential to alter the physicochemical properties (e.g., ice nucleation ability) of mineral dust particles in the atmosphere.

  12. The nature and formation of aeolian mineral dust material

    NASA Astrophysics Data System (ADS)

    Smalley, Ian; O'hara-Dhand, Ken; McLaren, Sue

    2013-04-01

    Aeolian dust affects climate and records past climates. It has become a much studied material but there has been a certain lack of emphasis on the actual nature of the dust, and an even greater neglect of actual production mechanisms for dust particles. Huge amounts of dust may be raised from the Bodele depression and other parts of North Africa, and much of it may be carried across the North Atlantic to aid in soil formation in Brazil. But what does it consist of? We know that much of the Bodele dust is diatoms from old Lake Chad, but what of the lithological inorganic mineral content? A very crude division of aeolian dust into large dust(say around 20-50um) and small dust (2-5um)has been proposed. Much of the study of loess has been confused by the failure to make this distinction, and similar problems may arise in the study of the finer fractions of aeolian dust. Much aeolian material is clay-mineral based- formed from clay mineral aggregates(CMA), from lake bottom sediments. This can form large dust particles, as in parna in Australia, but also contributes largely to small long travel aerosolic dust. Another major contributor is the quartz fragment. The large dust for classic loess deposits is mostly quartz silt- and there is considerable discussion about the controls that affect quartz silt. There are some interesting modalities in the world of quartz particle sedimentology which need to be examined. Quartz sand (say 200-500um) is the key initiating material and the formation processes for quartz sand have a down-the-line effect on the formation of smaller particles. The central observation is the action of two processes- a eutectic-like reaction in the proto-rock granite which defines the essential nature of sand particles, and the high-low displacive crystallographic transformation which introduces tensile stresses into the quartz particle systems. The limited range of eutectic particle size means a limited range of tensile stresses. A neat combination of

  13. Deposition Rates and Characterization of Arabian Mineral Dust

    NASA Astrophysics Data System (ADS)

    Puthan Purakkal, J.; Stenchikov, G. L.; Engelbrecht, J. P.

    2015-12-01

    Airborne mineral dust directly and indirectly impacts on global climate, continental and marine biochemistry, human and animal health, agriculture, equipment, and visibility. Annual global dust emissions are poorly known with estimates differing by a factor of at least two. Local dust emission and deposition rates are even less quantified. Dust deposition rate is a key parameter, which helps to constrain the modeled dust budget of the atmosphere. However, dust deposition remains poorly known, due to the limited number of reliable measurements. Simulations and satellite observations suggest that coastal dusts contribute substantially to the total deposition flux into the Red Sea. Starting December 2014, deposition samplers, both the "frisbee" type, and passive samplers for individual particle scanning electron microscopy were deployed at King Abdullah University of Science and Technology (KAUST), along the Red Sea in Saudi Arabia. Sampling periods of one month were adopted. The deposition rates range from 3 g m-2 month-1 for fair weather conditions to 23 g m-2 month-1 for high dust events. The X-ray diffraction (XRD) analyses of deposited dust samples show mineralogical compositions different from any of the parent soils, the former consisting mainly of gypsum, calcite, and smaller amounts of albite, montmorillonite, chlorite, quartz and biotite. The deposited dust samples on the other hand contain more gypsum and less quartz than the previously collected soil samples. This presentation discusses the results from XRD, chemical analysis and SEM-based individual particle analysis of the soils and the deposited dust samples. The monthly dust accumulation rates and their seasonal and spatial variability are compared with the regional model predictions. Data from this study provide an observational basis for validating the regional dust mass balance along the Arabian Red Sea coastal plain.

  14. The role of airborne mineral dusts in human disease

    NASA Astrophysics Data System (ADS)

    Morman, Suzette A.; Plumlee, Geoffrey S.

    2013-06-01

    Exposure to fine particulate matter (PM) is generally acknowledged to increase risk for human morbidity and mortality. However, particulate matter (PM) research has generally examined anthropogenic (industry and combustion by-products) sources with few studies considering contributions from geogenic PM (produced from the Earth by natural processes, e.g., volcanic ash, windborne ash from wildfires, and mineral dusts) or geoanthropogenic PM (produced from natural sources by processes that are modified or enhanced by human activities, e.g., dusts from lakebeds dried by human removal of water, dusts produced from areas that have undergone desertification as a result of human practices). Globally, public health concerns are mounting, related to potential increases in dust emission from climate related changes such as desertification and the associated long range as well as local health effects. Recent epidemiological studies have identified associations between far-traveled dusts from primary sources and increased morbidity and mortality in Europe and Asia. This paper provides an outline of public health research and history as it relates to naturally occurring inorganic mineral dusts. We summarize results of current public health research and describe some of the many challenges related to understanding health effects from exposures to dust aerosols.

  15. Observation of nitrate coatings on atmospheric mineral dust particles

    NASA Astrophysics Data System (ADS)

    Li, W. J.; Shao, L. Y.

    2009-03-01

    Nitrate compounds have received much attention because of their ability to alter the hygroscopic properties and cloud condensation nuclei (CCN) activity of mineral dust particles in the atmosphere. However, very little is known about specific characteristics of ambient nitrate-coated mineral particles on an individual particle scale. In this study, sample collection was conducted during brown haze and dust episodes between 24 May and 21 June 2007 in Beijing, northern China. Sizes, morphologies, and compositions of 332 mineral dust particles together with their coatings were analyzed using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) microanalyses. Structures of some mineral particles were verified using selected-area electron diffraction (SAED). TEM observation indicates that approximately 90% of the collected mineral particles are covered by visible coatings in haze samples whereas only 5% are coated in the dust sample. 92% of the analyzed mineral particles are covered with Ca-, Mg-, and Na-rich coatings, and 8% are associated with K- and S-rich coatings. The majority of coatings contain Ca, Mg, O, and N with minor amounts of S and Cl, suggesting that they are possibly nitrates mixed with small amounts of sulfates and chlorides. These nitrate coatings are strongly correlated with the presence of alkaline mineral components (e.g., calcite and dolomite). CaSO4 particles with diameters from 10 to 500 nm were also detected in the coatings including Ca(NO3)2 and Mg(NO3)2. Our results indicate that mineral particles in brown haze episodes were involved in atmospheric heterogeneous reactions with two or more acidic gases (e.g., SO2, NO2, HCl, and HNO3). Mineral particles that acquire hygroscopic nitrate coatings tend to be more spherical and larger, enhancing their light scattering and CCN activity, both of which have cooling effects on the climate.

  16. Modeling light scattering by mineral dust particles using spheroids

    NASA Astrophysics Data System (ADS)

    Merikallio, Sini; Nousiainen, Timo

    Suspended dust particles have a considerable influence on light scattering in both terrestrial and planetary atmospheres and can therefore have a large effect on the interpretation of remote sensing measurements. Assuming dust particles to be spherical is known to produce inaccurate results when modeling optical properties of real mineral dust particles. Yet this approximation is widely used for its simplicity. Here, we simulate light scattering by mineral dust particles using a distribution of model spheroids. This is done by comparing scattering matrices calculated from a dust optical database of Dubovik et al. [2006] with those measured in the laboratory by Volten et al. [2001]. Wavelengths of 441,6 nm and 632,8 nm and refractive indexes of Re = 1.55 -1.7 and Im = 0.001i -0.01i were adopted in this study. Overall, spheroids are found to fit the measurements significantly better than Mie spheres. Further, we confirm that the shape distribution parametrization developed in Nousiainen et al. (2006) significantly improves the accuracy of simulated single-scattering for small mineral dust particles. The spheroid scheme should therefore yield more reliable interpretations of remote sensing data from dusty planetary atmospheres. While the spheroidal scheme is superior to spheres in remote sensing applications, its performance is far from perfect especially for samples with large particles. Thus, additional advances are clearly possible. Further studies of the Martian atmosphere are currently under way. Dubovik et al. (2006) Application of spheroid models to account for aerosol particle nonspheric-ity in remote sensing of desert dust, JGR, Vol. 111, D11208 Volten et al. (2001) Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm, JGR, Vol. 106, No. D15, pp. 17375-17401 Nousiainen et al. (2006) Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids, JQSRT 101, pp. 471-487

  17. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    NASA Astrophysics Data System (ADS)

    Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

    2013-08-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

  18. Nanoparticulate mineral matter from basalt dust wastes.

    PubMed

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region.

  19. Nanoparticulate mineral matter from basalt dust wastes.

    PubMed

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. PMID:26551199

  20. On the visibility of airborne volcanic ash and mineral dust

    NASA Astrophysics Data System (ADS)

    Weinzierl, B.; Sauer, D. N.; Minikin, A.; Reitebuch, O.; Dahlkötter, F.; Mayer, B. C.; Emde, C.; Tegen, I.; Gasteiger, J.; Petzold, A.; Veira, A.; Kueppers, U.; Schumann, U.

    2012-12-01

    After the eruption of the Eyjafjalla volcano (Iceland) in April 2010 which caused the most extensive restrictions of the airspace over Europe since the end of World War II, the aviation safety concept of avoiding "visible ash", i.e. volcanic ash that can be seen by the human eye, was recommended. However so far, no clear definition of "visible ash" and no relation between the visibility of an aerosol layer and related aerosol mass concentrations are available. The goal of our study is to assess whether it is possible from the pilot's perspective in flight to detect the presence of volcanic ash and to distinguish between volcanic ash and other aerosol layers just by sight. In our presentation, we focus the comparison with other aerosols on aerosol types impacting aviation: Besides volcanic ash, dust storms are known to be avoided by aircraft. We use in-situ and lidar data as well photographs taken onboard the DLR research aircraft Falcon during the Saharan Mineral Dust Experiments (SAMUM) in 2006 and 2008 and during the Eyjafjalla volcanic eruption in April/May 2010. We complement this analysis with numerical modelling, using idealized radiative transfer simulations with the 3D Monte Carlo radiative transfer code MYSTIC for a variety of selected viewing geometries. Both aerosol types, Saharan mineral dust and volcanic ash, show an enhanced coarse mode (> 1 μm) aerosol concentration, but volcanic ash aerosol additionally contains a significant number of Aitken mode particles (< 150 nm). Volcanic ash is slightly more absorbing than mineral dust, and the spectral behaviour of the refractive index is slightly different. According to our simulations, these differences are not detectable just by human eye. Furthermore, our data show, that it is difficult to define a lower threshold for the visibility of an aerosol layer because the visual detectability depends on many parameters, including the thickness of the aerosol layer, the brightness and color contrast between the

  1. Dust from mineral extraction: regulation of emissions in England

    NASA Astrophysics Data System (ADS)

    Marker, Brian

    2013-04-01

    The United Kingdom, which includes England, has fairly high levels of rainfall but sporadic droughts occur especially in the east. Mineral working gives rise to dust. Concerns about dust soiling are major source of public objections to new minerals extraction operations. Dust emissions from mineral workings are a significant cause of public concern in the United Kingdom and are recognised as sources of health concerns and nuisance. Emissions are controlled through a number of complementary sets of regulations that are generally well observed by the industry and well enforced by the relevant public authorities. comprehensive system of regulation, based on European and national law, to deal with all aspects of these operations including pollution control, planning, occupational health and safety and statutory nuisances. Most minerals applications are subject to EIA which forms that basis for planning and environmental conditions and monitoring of operations. There are limit values on PM10 and PM2.5 in air, and for potentially harmful elements (PHEs) in soils and water, derived from European regulations but, as yet, no limit values for PHEs (other than radioactive materials) in air. Stakeholder engagement is encouraged so that members of the public can express concerns during minerals operations and operators can quickly deal with these. While some effects inevitably remain, the levels of dust emissions are kept low through good site design and management, proper use of machinery which is equipped to minimise emissions, and good training of the workforce. Operational sites are required to have dust monitoring equipment located outside the site boundary so that any emerging problems can be detected and addressed quickly.

  2. Contributions of dust exposure and cigarette smoking to emphysema severity in coal miners in the United States

    SciTech Connect

    Kuempel, E.D.; Wheeler, M.W.; Smith, R.J.; Vallyathan, V.; Green, F.H.Y.

    2009-08-15

    Previous studies have shown associations between dust exposure or lung burden and emphysema in coal miners, although the separate contributions of various predictors have not been clearly demonstrated. The objective was to quantitatively evaluate the relationship between cumulative exposure to respirable coal mine dust, cigarette smoking, and other factors on emphysema severity. The study group included 722 autopsied coal miners and nonminers in the United States. Data on work history, smoking, race, and age at death were obtained from medical records and questionnaire completed by next-of-kin. Emphysema was classified and graded using a standardized schema. Job-specific mean concentrations of respirable coal mine dust were matched with work histories to estimate cumulative exposure. Relationships between various metrics of dust exposure (including cumulative exposure and lung dust burden) and emphysema severity were investigated in weighted least squares regression models. Emphysema severity was significantly elevated in coal miners compared with nonminers among ever- and never-smokers (P < 0.0001). Cumulative exposure to respirable coal mine dust or coal dust retained in the lungs were significant predictors of emphysema severity (P < 0.0001) after accounting for cigarette smoking, age at death, and race. The contributions of coal mine dust exposure and cigarette smoking were similar in predicting emphysema severity averaged over this cohort. Coal dust exposure, cigarette smoking, age, and race are significant and additive predictors of emphysema severity in this study.

  3. Mineral dust exposure and free radical-mediated lung damage

    SciTech Connect

    Doelman, C.J.; Leurs, R.; Oosterom, W.C.; Bast, A. )

    1990-01-01

    Chronic exposure to several types of mineral dust particles induces an inflammatory reaction in the lung. Dust particles activate alveolar macrophages and prime leukocytes (neutrophils, eosinophils, and basophils), leading to an enhanced release of reactive oxygen species. Sometimes mineral dust particles also contain radicals. Reactive oxygen species (superoxide anion radical, hydrogen peroxide, hydroxyl radical, and singlet oxygen) may lead to tissue damage. These are able to break DNA strands, to destroy proteins, and to induce the process of lipid peroxidation. The effects of oxygen radicals on the beta-adrenergic and muscarinic receptor response of the guinea pig and rat tracheal strip are described. The beta-adrenergic receptor response appeared to be more susceptible to oxidative stress than the muscarinic receptor response. This may lead to an autonomic imbalance on exposure to oxygen radicals. The lipid peroxidation product 4-hydroxy-2,3-trans-nonenal diminished the beta-adrenergic responsiveness in guinea pig tracheal preparations. Histologic examinations indicated that at low concentrations of cumene hydroperoxide (10(-4) M) the epithelial layer of rat trachea was already destroyed, whereas no effect on the muscarinic response was found. Oxygen radical-mediated damage in lung tissue may lead to lung emphysema, hyperresponsiveness, and hypersensitivity. Pharmacotherapeutic interventions that prevent initiation or propagation of these free radical reactions may have a beneficial effect in mineral dust-associated lung disease. 70 references.

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

    NASA Astrophysics Data System (ADS)

    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

  5. Mineralogical, Chemical, and Optical Interrelationships of Airborne Mineral Dusts

    NASA Astrophysics Data System (ADS)

    Engelbrecht, J. P.; Moosmuller, H.; Pincock, S. L.; Jayanty, R. K. M.; Casuccio, G.

    2014-12-01

    The purpose of the project was to provide information on the mineralogical, chemical and physical interrelationships of re-suspended mineral dust samples collected as grab samples from global dust sources. Surface soil samples were collected from about 65 desert sites, including the southwestern USA (12), Mali (3), Chad (3), Morocco (1), Canary Islands (8), Cape Verde (1), Djibouti (1), Afghanistan (3), Iraq (6), Kuwait (5), Qatar (1), UAE (1), Serbia (3), China (5), Namibia (3), Botswana (4), Australia (3), and Chile (1). The < 38 μm sieved fraction of each sample was re-suspended in an entrainment chamber, from which the airborne mineral dust could be monitored, sampled and analyzed. Instruments integrated into the entrainment facility included two PM10 and two PM2.5 filter samplers, a beta attenuation gauge for the continuous measurement of PM10 and PM2.5 particulate mass fractions, an aerodynamic particle size (APS) analyzer, and a three wavelength (405, 532, 781nm) photoacoustic resonator with integrating reciprocal nephelometer for monitoring absorption and scattering coefficients during the dust re-suspension process. Filter sample media included Teflon® membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore® filters for individual particle analysis by Scanning Electron Microscopy (SEM). The < 38 μm sieved fractions were also analyzed by X-ray diffraction for their mineral content while the > 38 μm, < 125 μm soil fractions were mineralogically characterized by optical microscopy. We will be presenting results on the optical measurements, also showing the relationship between single scattering albedo (SSA) at three different wavelengths, and chemical as well as mineralogical content and interdependencies of the entrained dust samples. Examples showing the relationships between the single scattering albedos of airborne dusts, and iron (Fe) in hematite, goethite, and clay minerals (montmorillonite, illite, palygorskite), will

  6. Distribution of Atmospheric Mineral Dust across Dryland Ecosystems (Invited)

    NASA Astrophysics Data System (ADS)

    Reynolds, R. L.; Goldstein, H.; Miller, M. E.; Neff, J. C.; Fernandez, D.; Reheis, M. C.

    2010-12-01

    Deposited atmospheric dust in surface sediments of dry landscapes can be identified using geochemical, isotopic, mineralogical, and textural methods that provide compositional contrasts between surficial sediment and local bedrock. In some settings, detrital minerals that are present in surficial sediment but absent in nearby bedrock can be used as proxies for concentration of far-traveled dust. For example, silt-sized, titanium-bearing magnetite is found in silty sediment on high, isolated landforms underlain by Mesozoic and Paleozoic sandstone, which lack such magnetite, from the Mojave Desert eastward across the Colorado Plateau. Magnetite amounts within the top 10 cm of these sediments correlate (r2= 0.54) with amounts of potential plant nutrients, revealing the importance of mineral dust to fertility across ecosystems. Systematic eastward declines in magnetite (determined using magnetic susceptibility or isothermal remanent magnetization, IRM) and Ti indicate dominant dust sources from igneous terrain in the west. Variations in lead isotopes imply that most anthropogenic dust contributions are sourced from the west, consistent with the regional distribution of urban sources. Similar relations are found across gently sloping, dominantly sandy grassland surfaces that have undergone sediment sorting by aeolian and slope-wash processes. In undisturbed settings, fertility indicators and dust amounts (derived from IRM) correlate tightly (r2 as high as 0.96 between IRM and plant nutrients), and the dust amounts are significantly greater than for settings currently grazed by domestic livestock and even those at which grazing ceased 35 years ago. These results, complemented by other field and compositional studies, reveal that disturbance of dry, upland landscapes commonly promotes wind erosion, which then depletes surfaces of originally deposited dust, including aeolian magnetite. Declines in soil fertility, soil fines, and water-holding capacity in these settings can

  7. Modeling the processing of mineral iron during dust transport

    NASA Astrophysics Data System (ADS)

    Vogelsberg, Ulrike; Wolke, Ralf; Tilgner, Andreas; Tegen, Ina; Herrmann, Hartmut

    2014-05-01

    The Saharan desert and the Gobi desert are the main contributors to Aeolian desert dust, which is a major source of micronutrients to the remote ocean regions. Micronutrients, such as transition metals like iron or copper, are regarded essential for biological processes of different marine species. In this context recent studies have shown that soluble iron, since it is generally the most abundant transition metal in dust particles, has the ability to control marine productivity and thereby likely influence the CO2- budget. Nevertheless, the processing of desert dust leading to the release of soluble iron still lacks sufficient understanding since several factors control the solubilization process. Especially anthropogenic emissions are regarded to significantly add to the amount of soluble iron by acidification of dust particles or by the direct emission of soluble iron comprised, e.g. in coal fly ash. For the investigation of the dissolution process of iron that takes place during dust transportation the spectral air parcel model SPACCIM is used. A mechanism describing the precipitation and dissolution of mineral particles by heterogeneous surface reactions has been implemented. Trajectory properties were derived from COSMO-MUSCAT simulations or from re-analysis data by HYSPLIT. Differences in the chemical composition and the amount of anthropogenic and naturally emitted species on the North African continent and the highly industrialized region of South-East Asia have considerable impact on the acidification of the desert dust. Under this aspect, special cases of dust outbreaks of the Saharan desert and the Gobi desert are investigated and compared with focus on soluble iron produced.

  8. The impacts of mineral dust on organized mesoscale deep convection

    NASA Astrophysics Data System (ADS)

    Seigel, Robert Brian

    The overarching goal of this research is to investigate how mineral dust can impact organized deep moist convection using numerical modeling. This is achieved through four modeling studies that each address a different aspect of organized mesoscale DMC. The first study uses the Regional Atmospheric Modeling System (RAMS) to simulate a supercell storm in order to examine the pathways in which mineral dust is entrained into DMC. This is achieved by simulating a supercell within three commonly observed dust regimes. Results indicate that the supercell in EXP-BACKGROUND ingests large dust concentrations ahead of the rear-flank downdraft (RFD) cold pool. Conversely, dust lofted by the cold pool in EXP-STORM is ingested by the supercell in relatively small amounts via a narrow corridor generated by turbulent mixing between the RFD cold pool and ambient air. The addition of a convergence boundary in EXP-BOUNDARY is found to act as an additional source of dust for the supercell and represents the case between EXP-BACKGROUND and EXP-STORM. Results demonstrate the importance of using an appropriate dust parameterization when modeling DMC, especially within more arid regions. The second study utilizes an idealized simulation of a nocturnal squall line to assess and isolate the individual responses in a squall line that arise (1) from radiation, (2) from dust altering the microphysics, as well as (3) from the synergistic effects between (1) and (2). To accomplish these tasks, we again use RAMS set up as a cloud-resolving model (CRM). Results indicate that RADIATION acts to increase precipitation, intensify the cold pool, and enhance the mesoscale organization of the squall line due to radiation-induced changes in the microphysics that appear to initiate from cloud top cooling. Conversely, DUST MICRO decreases precipitation, weakens the cold pool, and weakens the mesoscale organization of the squall line due to an enhancement of the warm rain process. SYNERGY shows little

  9. Characterization of mineral dust aerosols during the Saharan Dust Experiment (SHADE)

    NASA Astrophysics Data System (ADS)

    Léon, J.-F.; Tanré, D.; Haywood, J.; Pelon, J.; Kaufman, Y. J.

    2003-04-01

    Aerosols are known to be important in determining the Earth’s radiative balance. Dust aerosols are particularly interesting since, in addition to their scattering and absorbing properties that affect the solar radiation, they also perturb the terrestrial radiation. In addition, recent studies have shown that a significant proportion of mineral dust in the atmosphere may be of anthropogenic origin and therefore they may have an important role in climate change by exerting a significant radiative forcing. The Saharan Dust Experiment was designed to better determine the parameters that are relevant for computing the direct radiative effect of mineral dust. Two aircraft combining in situ measurements and remote sensing instruments were coordinated with satellite overpasses during the experiment which was based in Cape Verde during the period September 20-28, 2000. These in-situ and remotely sensed data provide valuable information on the microphysical, optical properties and radiative effects of a very large mineral dust outbreak with aerosol optical thickness up to 1.5. A new approach based on a synergy between active (lidar) and passive (spaceborne radiometer) remote sensing has been used to investigate the vertical structure of the dust plume. The retrieved profiles of extinction compare well with in situ aircraft measurements. Profiles derived from lidar measurements on September 25 highlight the presence of the so-called Saharan Air Layer, located between 2.2 and 4.5 km. Another dust layer within the sub-Saharan transition layer over the marine boundary layer is also observed. In this second layer, the effective radius of particles is significantly smaller than in the aloft layer. The trajectory analyses and the Total Mapping Ozone Spectrometer Aerosol Index suggest that the aerosols present at 1500m originates from West Mauritania. The higher aerosol layer originates from southern Algeria which confirms the difference of altitude of the dust transport

  10. Clay minerals in primitive meteorites and interplanetary dust 1

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Keller, L. P.

    1991-01-01

    Many meteorites and interplanetary dust particles (IDPs) with primitive compositions contain significant amounts of phyllosilicate minerals, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period of the solar system. These meteorites are chondrites (near solar composition) of the carbonaceous and ordinary varieties. The former are subdivided (according to bulk composition and petrology) into CI, CM, CV, CO, CR, and ungrouped classes. IDPs are extraterrestrial particulates, collected in stratosphere, which have chemical compositions indicative of a primitive origin; they are typically distinct from the primitive meteorites. Characterization of phyllosilicates in these materials is a high priority because of the important physico-chemical information they hold. The most common phyllosilicates present in chondritic extraterrestrial materials are serpentine-group minerals, smectites, and micas. We discuss these phyllosilicates and describe the interpretation of their occurrence in meteorites and IDPs and what this indicates about history of their parent bodies, which are probably the hydrous asteroids.

  11. The role of mineral dust aerosols in polar amplification

    NASA Astrophysics Data System (ADS)

    Lambert, F.; Kug, J.; Park, R.; Jin, F.; Lee, J. H.

    2010-12-01

    During today’s global warming, as well as during glacial-interglacial changes, temperature increase is larger in polar areas than the global average, a phenomenon called “polar amplification”. Model studies suggest ice cap melting due to greenhouse gas induced temperature rise, and consequent decrease of albedo and enhanced oceanic and atmospheric heat transport, as the primary cause for this phenomenon in nowadays Arctic. However, the underlying causes for polar amplification on glacial-interglacial timescales are still unclear, especially in the Antarctic where sea ice coverage does not change as drastically as in the North. Recent results have shown that the temperature increase is not limited to the surface and that these changes can not be explained by snow and ice changes alone. Starting with dust flux measurements from ice cores in Greenland and Antarctica, we have estimated tropospheric concentrations using deposition velocities and vertical concentration profiles for Holocene and LGM conditions from the National Center for Atmospheric Research’s Community Climate System Model (CCSM3) and a 3-D global chemical transport model (GEOS-Chem). The radiative forcing due to mineral dust aerosols was then estimated using the GEOS-Chem model, based on the particle properties found in the ice. Preliminary results point towards positive forcing of dust because of the high albedo of the underlying ice sheets.

  12. Red Dawn: Characterizing Iron Oxide Minerals in Atmospheric Dust

    NASA Astrophysics Data System (ADS)

    Yauk, K.; Ottenfeld, C. F.; Reynolds, R. L.; Goldstein, H.; Cattle, S.; Berquo, T. S.; Moskowitz, B. M.

    2012-12-01

    Atmospheric dust is comprised of many components including small amounts of iron oxide minerals. Although the iron oxides make up a small weight percent of the bulk dust, they are important because of their roles in ocean fertilization, controls on climate, and as a potential health hazard to humans. Here we report on the iron oxide mineralogy in dust from a large dust storm, dubbed Red Dawn, which engulfed eastern Australia along a 3000 km front on 23 September 2009. Red Dawn originated from the lower Lake Eyre Basin of South Australia, western New South Wales (NSW) and southwestern Queensland and was the worst dust storm to have hit the city of Sydney in more than 60 years. Dust samples were collected from various locations across eastern Australia (Lake Cowal, Orange, Hornsby, Sydney) following the Red Dawn event. Our dust collection provides a good opportunity to study the physical and mineralogical properties of iron oxides from Red Dawn using a combination of reflectance spectroscopy, Mössbauer spectroscopy (MB), and magnetic measurements. Magnetization measurements from 20-400 K reveal that magnetite/maghemite, hematite and goethite are present in all samples with magnetite occurring in trace amounts (< 0.5wt%). However, the amount of magnetite/maghemite even in trace concentrations generally increases from Lake Cowal from west to east (0.01 to 0.29 wt%), with highest magnetite contents in the urban-Sydney sites. These observations indicate the additions of magnetite from local urban sources. Variable temperature Mössbauer spectroscopy (300 K and 4.2 K) indicate that goethite and hematite compose approximately 25-45 % of the Fe-bearing phases in the Orange and Lake Cowal samples. Goethite is more abundant than hematite in the Lake Cowal samples whereas the opposite is observed for Orange. Hematite is observed at both temperatures but goethite only at 4.2 K. The identification of goethite in Mössbauer analyses at low-temperature but not at room temperature

  13. Modification of Saharan Mineral Dust during Transport across the Atlantic Ocean - Overview and Results from the SALTRACE Field Experiment

    NASA Astrophysics Data System (ADS)

    Weinzierl, Bernadett; Ansmann, Albert; Reitebuch, Oliver; Freudenthaler, Volker; Müller, Thomas; Kandler, Konrad; Groß, Silke; Sauer, Daniel; Althausen, Dietrich; Toledano, Carlos

    2014-05-01

    At present one of the largest uncertainties in our understanding of global climate concerns the interaction of aerosols with clouds and atmospheric dynamics. In the climate system, mineral dust aerosol is of key importance, because mineral dust contributes to about half of the global annual particle emissions by mass. Although our understanding of the effects of mineral dust on the atmosphere and the climate improved during the past decade, many questions such as the change of the dust size distribution during transport across the Atlantic Ocean and the associated impact on the radiation budget, the role of wet and dry dust removal mechanisms during transport, and the complex interaction between mineral dust and clouds remain open. The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE: http://www.pa.op.dlr.de/saltrace) was conducted in June/July 2013 to investigate the transport and transformation of Saharan mineral dust during long-range transport from the Sahara across the Atlantic Ocean into the Caribbean. SALTRACE is a German initiative combining ground-based and airborne in-situ and lidar measurements with meteorological data, long-term measurements, satellite remote sensing and modeling which involved many national and international partners. During SALTRACE, the DLR Falcon research aircraft was based at Sal, Cape Verde, between 11 and 17 June 2013, and at Barbados between 18 June and 11 July 2013. The Falcon was equipped with a suite of in-situ instruments for the measurement of microphysical and optical aerosol properties, with sampling devices for offline particle analysis, with a nadir-looking 2-µm wind lidar, with dropsondes and instruments for standard meteorological parameters. Ground-based lidar and in-situ instruments were deployed in Cape Verde, Barbados and Puerto Rico. During SALTRACE, mineral dust from five dust outbreaks was studied by the Falcon research aircraft between Senegal, the Caribbean and Florida

  14. NMMB/BSC-DUST: an online mineral dust atmospheric model from meso to global scales

    NASA Astrophysics Data System (ADS)

    Haustein, K.; Pérez, C.; Jorba, O.; Baldasano, J. M.; Janjic, Z.; Black, T.; Nickovic, S.

    2009-04-01

    While mineral dust distribution and effects are important at global scales, they strongly depend on dust emissions that are controlled on small spatial and temporal scales. Most global dust models use prescribed wind fields provided by meteorological centers (e.g., NCEP and ECMWF) and their spatial resolution is currently never better than about 1°×1°. Regional dust models offer substantially higher resolution (10-20 km) and are typically coupled with weather forecast models that simulate processes that GCMs either cannot resolve or can resolve only poorly. These include internal circulation features such as the low-level nocturnal jet which is a crucial feature for dust emission in several dust ‘hot spot' sources in North Africa. Based on our modeling experience with the BSC-DREAM regional forecast model (http://www.bsc.es/projects/earthscience/DREAM/) we are currently implementing an improved mineral dust model [Pérez et al., 2008] coupled online with the new global/regional NMMB atmospheric model under development in NOAA/NCEP/EMC [Janjic, 2005]. The NMMB is an evolution of the operational WRF-NMME extending from meso to global scales. The NMMB will become the next-generation NCEP model for operational weather forecast in 2010. The corresponding unified non-hydrostatic dynamical core ranges from meso to global scale allowing regional and global simulations. It has got an add-on non-hydrostatic module and it is based on the Arakawa B-grid and hybrid pressure-sigma vertical coordinates. NMMB is fully embedded into the Earth System Modeling Framework (ESMF), treating dynamics and physics separately and coupling them easily within the ESMF structure. Our main goal is to provide global dust forecasts up to 7 days at mesoscale resolutions. New features of the model include a physically-based dust emission scheme after White [1979], Iversen and White [1982] and Marticorena and Bergametti [1995] that takes the effects of saltation and sandblasting into account

  15. Relationship between Rock Varnish and Adjacent Mineral Dust Compositions Using Microanalytical Techniques

    NASA Astrophysics Data System (ADS)

    Macholdt, D.; Jochum, K. P.; Otter, L.; Stoll, B.; Weis, U.; Pöhlker, C.; Müller, M.; Kappl, M.; Weber, B.; Kilcoyne, A. L. D.; Weigand, M.; Al-Amri, A. M.; Andreae, M. O.

    2015-12-01

    Rock varnishes are up to 250 μm thick, Mn- and Fe-rich, dark black to brownish-orange lustrous rock coatings. Water and aeolian dust (60-70%), in combination with biological oxidation or inorganic precipitation processes, or even a combination of both, induce varnish growth rates of a few μm per 1000 a, indicating that element enrichment and aging processes are of major importance for the varnish formation. A combination of 200 nm-fs laser- and 213 nm-ns laser ablation- inductively coupled plasma-mass spectrometry (LA-ICP-MS), focused ion beam (FIB) slicing, and scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) was chosen for high-spatial-resolution analyses. The aim was to identify provenance, chemistry, and dynamics of the varnishes, and their formation over the millennia. To this end, mineral dust and adjacent varnishes were sampled in six arid to semi-arid deserts, in Israel, South Africa, California, and Saudi Arabia. Dust minerals incorporated in the varnishes were examined by STXM-NEXAFS spectroscopic and element mapping at the nm scale. Varnishes from different locations can be distinguished by element ratio plots of Pb/Ni vs. Mn/Ba. A comparison of dust element ratios of particles <50 μm to ratios of adjacent varnishes reveals much lower values for dust. However, the factors between the element ratios of dust and of varnish are similar for four of six regions (Mn/Ba: 6 ± 2; Pb/Ni: 4 ± 3). Two of the six regions diverge, which are South African (Mn/Ba: 20, Pb/Ni: 0.5) and Californian (Anza Borrego Desert: Mn/Ba: 4.5; Pb/Ni: 16.5) varnishes.The results indicate that the enrichment and degradation processes might be similar for most locations, and that Mn and Pb are preferably incorporated and immobilized in most varnishes compared to Ba and Ni. The Pb/Ni ratios of the South African varnishes are indicators for either a preferred incorporation of Ni compared to Pb from available dust, and

  16. Dust exposure and respiratory disease in U. S. coal miners

    SciTech Connect

    Seixas, N.S.

    1990-01-01

    This study examines the effectiveness of the dust standards set by the Coal Mine Health and Safety Act of 1969 in preventing obstructive lung disease by considering the exposure-response relationship in a group of miners whose exposure began in or after 1970 when the regulations took effect. Exposing-response relationships were examined among 1,270 miners from the National Study of Coal Workers' Pneumoconiosis. Cross-sectional and longitudinal associations between cumulative exposure and pulmonary function test results (FVC, FEV{sub 1}, and FEV{sub 1}/FVC) and respiratory symptoms were modeled using linear and logistic regression while controlling for smoking. The results over a 15 year exposure period indicated statistically significant positive associations of cumulative exposure with decrements in FEV{sub 1}, FEV{sub 1}/FVC, the likelihood of these indices being less than 80% of predicted, and symptoms, including chronic bronchitis, breathlessness and wheeze with shortness of breath. The estimated effect of exposure of FEV{sub 1} was 5.5 ml per mg/m{sup 3} -years which was substantially larger than previously reported estimates. However, examination of PFTs within five years of beginning work demonstrated a rapid initial exposure-related loss of both FVC and FEV{sub 1} and no additional exposure-related loss over the following 10 years. The results of the study suggest that exposure to coal mine dust at concentrations present since the CMHSA regulations were put into effect have not been completely successful in preventing respiratory effects. Determination of the long-term significance of the initial exposure-response relationship observed requires additional follow-up of this cohort.

  17. Global distribution of minerals in arid soils as lower boundary condition in dust models

    NASA Astrophysics Data System (ADS)

    Nickovic, Slobodan

    2010-05-01

    Mineral dust eroded from arid soils affects the radiation budget of the Earth system, modifies ocean bioproductivity and influences human health. Dust aerosol is a complex mixture of minerals. Dust mineral composition has several potentially important impacts to environment and society. Iron and phosphorus embedded in mineral aerosol are essential for the primary marine productivity when dust deposits over the open ocean. Dust also acts as efficient agent for heterogeneous ice nucleation and this process is dependent on mineralogical structure of dust. Recent findings in medical geology indicate possible role of minerals to human health. In this study, a new 1-km global database was developed for several minerals (Illite, Kaolinite, Smectite, Calcite, Quartz, Feldspar, Hematite and Gypsum) embedded in clay and silt populations of arid soils. For the database generation, high-resolution data sets on soil textures, soil types and land cover was used. Tin addition to the selected minerals, phosphorus was also added whose geographical distribution was specified from compiled literature and data on soil types. The developed global database was used to specify sources of mineral fractions in the DREAM dust model and to simulate atmospheric paths of minerals and their potential impacts on marine biochemistry and tropospheric ice nucleation.

  18. Mineral dust aerosols promote the formation of toxic nitropolycyclic aromatic compounds

    PubMed Central

    Kameda, Takayuki; Azumi, Eri; Fukushima, Aki; Tang, Ning; Matsuki, Atsushi; Kamiya, Yuta; Toriba, Akira; Hayakawa, Kazuichi

    2016-01-01

    Atmospheric nitrated polycyclic aromatic hydrocarbons (NPAHs), which have been shown to have adverse health effects such as carcinogenicity, are formed in part through nitration reactions of their parent polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. However, little is known about heterogeneous nitration rates of PAHs by gaseous NO2 on natural mineral substrates, such as desert dust aerosols. Herein by employing kinetic experiments using a flow reactor and surface analysis by Fourier transform infrared spectroscopy with pyridine adsorption, we demonstrate that the reaction is accelerated on acidic surfaces of mineral dust, particularly on those of clay minerals. In support of this finding, we show that levels of ambient particle-associated NPAHs in Beijing, China, significantly increased during heavy dust storms. These results suggest that mineral dust surface reactions are an unrecognized source of toxic organic chemicals in the atmosphere and that they enhance the toxicity of mineral dust aerosols in urban environments. PMID:27075250

  19. NMMB/BSC-DUST: an online mineral dust atmospheric model from meso to global scales

    NASA Astrophysics Data System (ADS)

    Haustein, K.; Pérez, C.; Jorba, O.; Baldasano, J. M.; Janjic, Z.; Black, T.; Nickovic, S.

    2009-04-01

    While mineral dust distribution and effects are important at global scales, they strongly depend on dust emissions that are controlled on small spatial and temporal scales. Most global dust models use prescribed wind fields provided by meteorological centers (e.g., NCEP and ECMWF) and their spatial resolution is currently never better than about 1°×1°. Regional dust models offer substantially higher resolution (10-20 km) and are typically coupled with weather forecast models that simulate processes that GCMs either cannot resolve or can resolve only poorly. These include internal circulation features such as the low-level nocturnal jet which is a crucial feature for dust emission in several dust ‘hot spot' sources in North Africa. Based on our modeling experience with the BSC-DREAM regional forecast model (http://www.bsc.es/projects/earthscience/DREAM/) we are currently implementing an improved mineral dust model [Pérez et al., 2008] coupled online with the new global/regional NMMB atmospheric model under development in NOAA/NCEP/EMC [Janjic, 2005]. The NMMB is an evolution of the operational WRF-NMME extending from meso to global scales. The NMMB will become the next-generation NCEP model for operational weather forecast in 2010. The corresponding unified non-hydrostatic dynamical core ranges from meso to global scale allowing regional and global simulations. It has got an add-on non-hydrostatic module and it is based on the Arakawa B-grid and hybrid pressure-sigma vertical coordinates. NMMB is fully embedded into the Earth System Modeling Framework (ESMF), treating dynamics and physics separately and coupling them easily within the ESMF structure. Our main goal is to provide global dust forecasts up to 7 days at mesoscale resolutions. New features of the model include a physically-based dust emission scheme after White [1979], Iversen and White [1982] and Marticorena and Bergametti [1995] that takes the effects of saltation and sandblasting into account

  20. Carbon dioxide sequestration in cement kiln dust through mineral carbonation

    SciTech Connect

    Deborah N. Huntzinger; John S. Gierke; S. Komar Kawatra; Timothy C. Eisele; Lawrence L. Sutter

    2009-03-15

    Carbon sequestration through the formation of carbonates is a potential means to reduce CO{sub 2} emissions. Alkaline industrial solid wastes typically have high mass fractions of reactive oxides that may not require preprocessing, making them an attractive source material for mineral carbonation. The degree of mineral carbonation achievable in cement kiln dust (CKD) under ambient temperatures and pressures was examined through a series of batch and column experiments. The overall extent and potential mechanisms and rate behavior of the carbonation process were assessed through a complementary set of analytical and empirical methods, including mass change, thermal analysis, and X-ray diffraction. The carbonation reactions were carried out primarily through the reaction of CO{sub 2} with Ca(OH){sub 2}, and CaCO{sub 3} was observed as the predominant carbonation product. A sequestration extent of over 60% was observed within 8 h of reaction without any modifications to the waste. Sequestration appears to follow unreacted core model theory where reaction kinetics are controlled by a first-order rate constant at early times; however, as carbonation progresses, the kinetics of the reaction are attenuated by the extent of the reaction due to diffusion control, with the extent of conversion never reaching completion. 35 refs., 3 figs., 1 tab.

  1. Carbon dioxide sequestration in cement kiln dust through mineral carbonation.

    PubMed

    Huntzinger, Deborah N; Gierke, John S; Kawatra, S Komar; Eisele, Timothy C; Sutter, Lawrence L

    2009-03-15

    Carbon sequestration through the formation of carbonates is a potential means to reduce CO2 emissions. Alkaline industrial solid wastes typically have high mass fractions of reactive oxides that may not require preprocessing, making them an attractive source material for mineral carbonation The degree of mineral carbonation achievable in cement kiln dust (CKD) underambienttemperatures and pressures was examined through a series of batch and column experiments. The overall extent and potential mechanisms and rate behavior of the carbonation process were assessed through a complementary set of analytical and empirical methods, including mass change, thermal analysis, and X-ray diffraction. The carbonation reactions were carried out primarily through the reaction of CO2 with Ca(OH)2, and CaCO3 was observed as the predominant carbonation product. A sequestration extent of over 60% was observed within 8 h of reaction without any modifications to the waste. Sequestration appears to follow unreacted core model theory where reaction kinetics are controlled by a first-order rate constant at early times; however, as carbonation progresses, the kinetics of the reaction are attenuated by the extent of the reaction due to diffusion control, with the extent of conversion never reaching completion.

  2. Carbon dioxide sequestration in cement kiln dust through mineral carbonation.

    PubMed

    Huntzinger, Deborah N; Gierke, John S; Kawatra, S Komar; Eisele, Timothy C; Sutter, Lawrence L

    2009-03-15

    Carbon sequestration through the formation of carbonates is a potential means to reduce CO2 emissions. Alkaline industrial solid wastes typically have high mass fractions of reactive oxides that may not require preprocessing, making them an attractive source material for mineral carbonation The degree of mineral carbonation achievable in cement kiln dust (CKD) underambienttemperatures and pressures was examined through a series of batch and column experiments. The overall extent and potential mechanisms and rate behavior of the carbonation process were assessed through a complementary set of analytical and empirical methods, including mass change, thermal analysis, and X-ray diffraction. The carbonation reactions were carried out primarily through the reaction of CO2 with Ca(OH)2, and CaCO3 was observed as the predominant carbonation product. A sequestration extent of over 60% was observed within 8 h of reaction without any modifications to the waste. Sequestration appears to follow unreacted core model theory where reaction kinetics are controlled by a first-order rate constant at early times; however, as carbonation progresses, the kinetics of the reaction are attenuated by the extent of the reaction due to diffusion control, with the extent of conversion never reaching completion. PMID:19368202

  3. An investigation into the relationship between coal workers' pneumoconiosis and dust exposure in U. S. coal miners

    SciTech Connect

    Attfield, M.D.; Morring, K. )

    1992-08-01

    The National Study of Coal Workers' Pneumoconiosis (NSCWP) is a large, continuing epidemiologic study of the respiratory health of U.S. coal miners. By using information from the study, prevalence of coal workers' pneumoconiosis (CWP) was related to indexes of dust exposure obtained from research and compliance sampling data. Clear relationships between prevalences of both simple CWP and progressive massive fibrosis (PMF) and estimated dust exposure were seen. Additional effects independently associated with coal rank (% carbon) and age were also seen. Logistic model fitting indicated that between 2% and 12% of miners exposed to a 2-mg/m3 dust environment in bituminous coal mines would be expected to have Category 2 or greater CWP after a 40-yr working life; PMF would be expected for between 1.3% and 6.7%. The risks for anthracite miners appeared to be greater. There was a suggestion of a background level of abnormality, not associated with dust exposure, but increasing with age. Although there are certain weaknesses in the data used to derive these exposure estimates, the results are in general agreement with, but somewhat greater than, some recent findings for British coal miners.

  4. Observation of Dust Aging Processes During Transport from Africa into the Caribbean - A Lagrangian Case Study

    NASA Astrophysics Data System (ADS)

    Weinzierl, B.; Sauer, D. N.; Walser, A.; Dollner, M.; Reitebuch, O.; Gross, S.; Chouza, F.; Ansmann, A.; Toledano, C.; Freudenthaler, V.; Kandler, K.; Schäfler, A.; Baumann, R.; Tegen, I.; Heinold, B.

    2014-12-01

    Aerosol particles are regularly transported over long distances impacting air quality, health, weather and climate thousands of kilometers downwind of the source. During transport, particle properties are modified thereby changing the associated impact on the radiation budget. Although mineral dust is of key importance for the climate system many questions such as the change of the dust size distribution during long-range transport, the role of wet and dry removal mechanisms, and the complex interaction between mineral dust and clouds remain open. In June/July 2013, the Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE: http://www.pa.op.dlr.de/saltrace) was conducted to study the transport and transformation of Saharan mineral dust. Besides ground-based lidar and in-situ instruments deployed on Cape Verde, Barbados and Puerto Rico, the DLR research aircraft Falcon was equipped with an extended aerosol in-situ instrumentation, a nadir-looking 2-μm wind lidar and instruments for standard meteorological parameters. During SALTRACE, five large dust outbreaks were studied by ground-based, airborne and satellite measurements between Senegal, Cape Verde, the Caribbean, and Florida. Highlights included the Lagrangian sampling of a dust plume in the Cape Verde area on 17 June which was again measured with the same instrumentation on 21 and 22 June 2013 near Barbados. Between Cape Verde and Barbados, the aerosol optical thickness (500 nm) decreased from 0.54 to 0.26 and the stratification of the dust layers changed significantly from a rather homogenous structure near Africa to a 3-layer structure with embedded cumulus clouds in the Caribbean. In the upper part of the dust layers in the Caribbean, the aerosol properties were similar to the observations near Africa. In contrast, much more variability in the dust properties was observed between 0.7 and 2.5 km altitude probably due to interaction of the mineral dust with clouds. In our

  5. Modeling Optical Properties of Mineral Dust over "The Great Indian Desert"

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Tripathi, S. N.

    2007-12-01

    The Thar desert, sometimes also described as 'The Great Indian Desert', lying in the Northwest part of India with an area of 0.32*106 km2, is known to be the source of natural mineral dust . The mineral dust particles are mostly non-spherical having sharp edges, which show different scattering signature compared to that of equivalent spheres while interacting with the radiation. Furthermore accurate mineralogical information, that governs their refractive indices, is essential for scattering calculations. The radiative impacts of dust particles therefore depend on their morphology and mineralogy. Most of the present satellites consider the particle to be spherical while retrieving their optical properties. Some newly launched spacecraft instruments such as MISR accounts for non spherical nature by including spheroid particles in its retrieval algorithm . Clearly there exits a need for improvement in dust model used in retrieval algorithm to account for their sharp edges together with their index of refraction based on the latest chemical composition at the sensing wavelengths. To the best of our knowledge no such attempt has been made to calculate the optical properties of dust particles over the Thar desert. In this study, the optical properties of mineral dust of the Thar desert has been modeled using T-matrix method with realistic dust shapes based on Scanning Electron Microscope images of the dust over the desert with particle size ranging from 0.1-1.0 ìm at wavelengths spanning from ultraviolet to near infrared (0.38-1.2ìm). Representative dust particles shapes considered are sphere, cylinder, spheroids and chebyshev together with realistic mineral dust composition. Mineralogical analysis of airborne dust over Northwest India has revealed the presence of only basic non-metallic minerals such as Quartz, Feldspar, Mica and Calcite, which posses negligible imaginary part of refractive index at considered wavelength domain, however, the subsequent dust sampling

  6. The global distribution of mineral dust and its impacts on the climate system: A review

    NASA Astrophysics Data System (ADS)

    Choobari, O. Alizadeh; Zawar-Reza, P.; Sturman, A.

    2014-03-01

    Mineral dust aerosols, the tiny soil particles suspended in the atmosphere, have a key role in the atmospheric radiation budget and hydrological cycle through their radiative and cloud condensation nucleus effects. Current understanding of spatial and temporal variations of mineral dust, as well as its impacts on the climate system and cloud properties is outlined. Mineral dust aerosols are blown into the atmosphere mainly from arid and semi-arid regions where annual rainfall is extremely low and substantial amounts of alluvial sediment have been accumulated over long periods. They are subject to long-range transport of an intercontinental scale, including North African dust plumes over the Atlantic Ocean, summer dust plumes from the Arabian Peninsula over the Arabian Sea and Indian Ocean and spring dust plumes from East Asia over the Pacific Ocean. Mineral dust aerosols influence the climate system and cloud microphysics in multiple ways. They disturb the climate system directly by scattering and partly absorbing shortwave and longwave radiation, semi-directly by changing the atmospheric cloud cover through evaporation of cloud droplets (i.e. the cloud burning effect), and indirectly by acting as cloud and ice condensation nuclei, which changes the optical properties of clouds (i.e. the first indirect effect), and may decrease or increase precipitation formation (i.e. the second indirect effect). Radiative forcing by mineral dust is associated with changes in atmospheric dynamics that may change the vertical profile of temperature and wind speed, through which a feedback effect on dust emission can be established.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Ice nucleation of bare and sulfuric acid-coated mineral dust particles and implication for cloud properties

    NASA Astrophysics Data System (ADS)

    Kulkarni, Gourihar; Sanders, Cassandra; Zhang, Kai; Liu, Xiaohong; Zhao, Chun

    2014-08-01

    Ice nucleation properties of atmospherically relevant dust minerals coated with soluble materials are not yet well understood. We determined ice nucleation ability of bare and sulfuric acid-coated mineral dust particles as a function of temperature (-25 to -35°C) and relative humidity with respect to water (RHw; 75 to 110%) for five different mineral dust types: (1) Arizona test dust, (2) illite, (3) montmorillonite, (4) K-feldspar, and (5) quartz. The particles were dry dispersed and size selected at 200 nm, and we determined the fraction of dust particles nucleating ice at various temperatures and RHw. Under water-subsaturated conditions, compared to bare dust particles, we found that coated particles showed a reduction in their ice nucleation ability. Under water-supersaturated conditions, however, we did not observe a significant coating effect (i.e., the bare and coated dust particles had nearly similar nucleating properties). X-ray diffraction patterns of the coated particles indicated that acid treatment altered the crystalline nature of the surface and caused structural disorder; thus, we concluded that the lack of such structured order reduced the ice nucleation efficiency of the coated particles in deposition ice nucleation mode. In addition, our single column model results show that coated particles significantly modify cloud properties such as ice crystal number concentration and ice water content compared to bare particles in water-subsaturated conditions. However, in water-supersaturated conditions, cloud properties differ only at warmer temperatures. These modeling results imply that future aged dust particle simulations should implement coating parameterizations to accurately predict cloud properties.

  9. Stimulation of alveolar macrophages by mineral dusts in vitro: luminol-dependent chemiluminescence study

    SciTech Connect

    Vilim, V.; Wilhelm, J.; Brzak, P.; Hurych, J.

    1987-02-01

    Luminol-dependent chemiluminescence (CL) of normal (nonactivated) rabbit alveolar macrophages (AMs) was measured in suspension upon stimulation by various size fractions of one quartz dust sample or by various mineral dusts (quartz, corundum, anatas, and chrysotile asbestos as an example of fibrous dust). The CL-triggering capacity of the tested dusts was inhibited by their preincubation with autologous serum. The intensity of luminol-dependent CL induced by particulate dusts upon their action on AMs depended on the kind of dust, on the dust particle sizes, and on the ratio of the number of particles to the number of cells in a given suspension. The cytotoxicity and/or fibrogenicity of the dust and its capacity to trigger the luminol-dependent CL of nonadherent AMs were not directly correlated.

  10. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2015-08-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of tranport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1-3 km) than at elevated altitude (> 3 km), resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations, modeling studies and

  11. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2016-02-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals

  12. Mineral dust photochemistry induces nucleation events in the presence of SO2.

    PubMed

    Dupart, Yoan; King, Stephanie M; Nekat, Bettina; Nowak, Andreas; Wiedensohler, Alfred; Herrmann, Hartmut; David, Gregory; Thomas, Benjamin; Miffre, Alain; Rairoux, Patrick; D'Anna, Barbara; George, Christian

    2012-12-18

    Large quantities of mineral dust particles are frequently ejected into the atmosphere through the action of wind. The surface of dust particles acts as a sink for many gases, such as sulfur dioxide. It is well known that under most conditions, sulfur dioxide reacts on dust particle surfaces, leading to the production of sulfate ions. In this report, for specific atmospheric conditions, we provide evidence for an alternate pathway in which a series of reactions under solar UV light produces first gaseous sulfuric acid as an intermediate product before surface-bound sulfate. Metal oxides present in mineral dust act as atmospheric photocatalysts promoting the formation of gaseous OH radicals, which initiate the conversion of SO(2) to H(2)SO(4) in the vicinity of dust particles. Under low dust conditions, this process may lead to nucleation events in the atmosphere. The laboratory findings are supported by recent field observations near Beijing, China, and Lyon, France.

  13. Building an industry-wide occupational exposure database for respirable mineral dust - experiences from the IMA dust monitoring programme

    NASA Astrophysics Data System (ADS)

    Houba, Remko; Vlaanderen, Jelle; Jongen, Richard; Kromhout, Hans

    2009-02-01

    Building an industry-wide database with exposure measurements of respirable mineral dust is a challenging operation. The Industrial Minerals Association (IMA-Europe) took the initiative to create an exposure database filled with data from a prospective and ongoing dust monitoring programme that was launched in 2000. More than 20 industrial mineral companies have been collecting exposure data following a common protocol since then. Recently in 2007 ArboUnie and IRAS evaluated the quality of the collected exposure data for data collected up to winter 2005/2006. The data evaluated was collected in 11 sampling campaigns by 24 companies at 84 different worksites and considered about 8,500 respirable dust measurements and 7,500 respirable crystalline silica. In the quality assurance exercise four criteria were used to evaluate the existing measurement data: personal exposure measurements, unique worker identity, sampling duration not longer than one shift and availability of a limit of detection. Review of existing exposure data in the IMA dust monitoring programme database showed that 58% of collected respirable dust measurements and 62% of collected respirable quartz could be regarded as 'good quality data' meeting the four criteria mentioned above. Only one third of the measurement data included repeated measurements (within a sampling campaign) that would allow advanced statistical analysis incorporating estimates of within- and between-worker variability in exposure to respirable mineral dust. This data came from 7 companies comprising measurements from 23 sites. Problematic data was collected in some specific countries and to a large extent this was due to local practices and legislation (e.g. allowing 40-h time weighted averages). It was concluded that the potential of this unique industry-wide exposure database is very high, but that considerable improvements can be made. At the end of 2006 relatively small but essential changes were made in the dust monitoring

  14. Mineral dust and major ion concentrations in snowpit samples from the NEEM site, Greenland

    NASA Astrophysics Data System (ADS)

    Kang, Jung-Ho; Hwang, Heejin; Hong, Sang Bum; Hur, Soon Do; Choi, Sung-Deuk; Lee, Jeonghoon; Hong, Sungmin

    2015-11-01

    Polar ice sheets conserve atmospheric aerosols at the time of snowfall, which can be used to reconstruct past climate and environmental conditions. We investigated mineral dust and major ion records in snowpit samples obtained from the northwestern Greenland ice sheet near the North Greenland Eemian Ice Drilling (NEEM) camp in June 2009. We analyzed the samples for mineral dust concentrations as well as stable water isotopes (δ18O, δD, and deuterium excess) and major ions (Cl-, SO42-, methanesulfonic acid (MSA), Na+, and Ca2+). Seasonal δ18O and δD cycles indicate that the snowpit samples covered a six-year period from spring 2003 to early summer 2009. Concentrations of mineral dust, nss-Ca2+, and nss-SO42- showed seasonal deposition events with maxima in the winter-spring layers. On the other hand, the Cl-/Na+ ratio and the concentrations of MSA exhibited maxima in the summer layers, making them useful indicators for the summer season. Moreover, an anomalous atmospheric mineral dust event was recorded at a depth of 165-170 cm corresponding to late winter 2005 to spring 2006. A back trajectory analysis suggests that a major contributor to the Greenland aerosol was an air mass passing over the Canadian Arctic and North America. Several trajectories point to Asian regions as a dust source. The mineral dust deposited at NEEM was strongly influenced by long-range atmospheric transport and dust input from arid source areas in northern China and Mongolia.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Aging process of Saharan dust during transport over the Atlantic Ocean: Calcite reactivity and sulfate coating

    NASA Astrophysics Data System (ADS)

    Desboeufs, K. V.; Cautenet, G.; Minvielle, F.; Lasserre, F.

    2003-04-01

    Several field measurements emphasized that dust particles are mixed with sulfate during their transport. This state of mixing could be important on the climatic effect of these particles, since the optical properties of particles are not conservative in the case of internal mixing, and the addition of soluble species on the dust can modify their capacity to act as CCN. The aging process of dust particles in Tropical Africa and Atlantic Ocean is investigated using the three dimensional transport RAMS and chemistry model coupled on line. To describe the mixing process of dust, we considered the chemical reaction occurring between the calcite (calcium carbonate) in the Saharan dust and the various sulfur species to yield sulfate coating. The results by the model predictions are consistent with field and observations studies. We will discuss about the potential consequences of this coating on the direct and indirect effect of mineral dust in the Earth radiative budget. An analysis of cloud occurrence observed by satellites and mixed dust content will be presented.

  17. Hunting for eruption ages in accessory minerals

    NASA Astrophysics Data System (ADS)

    Vazquez, J. A.

    2012-12-01

    A primary goal in geochronology is to provide precise and accurate ages for tephras that serve as chronostratigraphic markers for constraining the timing and rates of volcanism, sedimentation, climate change, and catastrophic events in Earth history. Zircon remains the most versatile accessory mineral for dating silicic tephras due to its common preservation in distal pyroclastic deposits, as well as the robustness of its U-Pb and U-series systems even after host materials have been hydrothermally altered or weathered. Countless studies document that zircon may be complexly zoned in age due to inheritance, contamination, recycling of antecrysts, protracted crystallization in long-lived magma reservoirs, or any combination of these. Other accessory minerals such as allanite or chevkinite can retain similar records of protracted crystallization. If the goal is to date the durations of magmatic crystallization, differentiation, and/or magma residence, then these protracted chronologies within and between accessory minerals are a blessing. However, if the goal is to date the timing of eruption with high precision, i.e., absolute ages with millennial-scale uncertainties, then this age zoning is a curse. Observations from ion microprobe 238U-230Th dating of Pleistocene zircon and allanite provide insight into the record of near-eruption crystallization in accessory minerals and serve as a guide for high-precision whole-crystal dating. Although imprecise relative to conventional techniques, ion probe analysis allows high-spatial resolution 238U-230Th dating that can document multi-millennial age distributions at the crystal scale. Analysis of unpolished rims and continuous depth profiling of zircon from small and large volume eruptions (e.g., Coso, Mono Craters, Yellowstone) reveals that the final several micrometers of crystallization often yield ages that are indistinguishable from associated eruption ages from the 40Ar/39Ar or (U-Th)/He methods. Using this approach, we

  18. Optical properties of mineral dust aerosol including analysis of particle size, composition, and shape effects, and the impact of physical and chemical processing

    NASA Astrophysics Data System (ADS)

    Alexander, Jennifer Mary

    distributions. The next goal of this work is to investigate if modeling methods developed in the studies of single mineral components can be generalized to predict the optical properties of more authentic aerosol samples which are complex mixtures of different minerals. Samples of Saharan sand, Iowa loess, and Arizona road dust are used here as test cases. T-matrix based simulations of the authentic samples, using measured particle size distributions, empirical mineralogies, and a priori particle shape models for each mineral component are directly compared with the measured IR extinction spectra and visible scattering profiles. This modeling approach offers a significant improvement over more commonly applied models that ignore variations in particle shape with size or mineralogy and include only a moderate range of shape parameters. Mineral dust samples processed with organic acids and humic material are also studied in order to explore how the optical properties of dust can change after being aged in the atmosphere. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acid. Clear differences in the light scattering properties are observed for all three processed mineral dust samples when compared to the unprocessed mineral dust or organic salt products. These interactions result in both internal and external mixtures depending on the sample. In addition, the presence of these organic materials can alter the mineral dust particle shape. Overall, however, these results demonstrate the need to account for the effects of atmospheric aging of mineral dust on aerosol optical properties. Particle shape can also affect the aerodynamic properties of mineral dust aerosol. In order to account for these effects, the dynamic shape factor is used to give a measure of particle asphericity. Dynamic shape factors of quartz are measured by mass and mobility selecting particles and measuring their vacuum aerodynamic diameter. From this, dynamic

  19. How the Assumed Size Distribution of Dust Minerals Affects the Predicted Ice Forming Nuclei

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Fridlind, A. M.; Pérez García-Pando, C.; Miller, R. L.; Knopf, D. A.

    2015-12-01

    The formation of ice in clouds depends on the availability of ice forming nuclei (IFN). Dust aerosol particles are considered the most important source of IFN at a global scale. Recent laboratory studies have demonstrated that the mineral feldspar provides the most efficient dust IFN for immersion freezing and together with kaolinite for deposition ice nucleation, and that the phyllosilicates illite and montmorillonite (a member of the smectite group) are of secondary importance.A few studies have applied global models that simulate mineral specific dust to predict the number and geographical distribution of IFN. These studies have been based on the simple assumption that the mineral composition of soil as provided in data sets from the literature translates directly into the mineral composition of the dust aerosols. However, these tables are based on measurements of wet-sieved soil where dust aggregates are destroyed to a large degree. In consequence, the size distribution of dust is shifted to smaller sizes, and phyllosilicates like illite, kaolinite, and smectite are only found in the size range <2 μm. In contrast, in measurements of the mineral composition of dust aerosols, the largest mass fraction of these phyllosilicates is found in the size range >2 μm as part of dust aggregates. Conversely, the mass fraction of feldspar is smaller in this size range, varying with the geographical location. This may have a significant effect on the predicted IFN number and its geographical distribution.An improved mineral specific dust aerosol module has been recently implemented in the NASA GISS Earth System ModelE2. The dust module takes into consideration the disaggregated state of wet-sieved soil, on which the tables of soil mineral fractions are based. To simulate the atmospheric cycle of the minerals, the mass size distribution of each mineral in aggregates that are emitted from undispersed parent soil is reconstructed. In the current study, we test the null

  20. How the Assumed Size Distribution of Dust Minerals Affects the Predicted Ice Forming Nuclei

    NASA Technical Reports Server (NTRS)

    Perlwitz, Jan P.; Fridlind, Ann M.; Garcia-Pando, Carlos Perez; Miller, Ron L.; Knopf, Daniel A.

    2015-01-01

    The formation of ice in clouds depends on the availability of ice forming nuclei (IFN). Dust aerosol particles are considered the most important source of IFN at a global scale. Recent laboratory studies have demonstrated that the mineral feldspar provides the most efficient dust IFN for immersion freezing and together with kaolinite for deposition ice nucleation, and that the phyllosilicates illite and montmorillonite (a member of the smectite group) are of secondary importance.A few studies have applied global models that simulate mineral specific dust to predict the number and geographical distribution of IFN. These studies have been based on the simple assumption that the mineral composition of soil as provided in data sets from the literature translates directly into the mineral composition of the dust aerosols. However, these tables are based on measurements of wet-sieved soil where dust aggregates are destroyed to a large degree. In consequence, the size distribution of dust is shifted to smaller sizes, and phyllosilicates like illite, kaolinite, and smectite are only found in the size range 2 m. In contrast, in measurements of the mineral composition of dust aerosols, the largest mass fraction of these phyllosilicates is found in the size range 2 m as part of dust aggregates. Conversely, the mass fraction of feldspar is smaller in this size range, varying with the geographical location. This may have a significant effect on the predicted IFN number and its geographical distribution.An improved mineral specific dust aerosol module has been recently implemented in the NASA GISS Earth System ModelE2. The dust module takes into consideration the disaggregated state of wet-sieved soil, on which the tables of soil mineral fractions are based. To simulate the atmospheric cycle of the minerals, the mass size distribution of each mineral in aggregates that are emitted from undispersed parent soil is reconstructed. In the current study, we test the null

  1. Alignment of atmospheric mineral dust due to electric field

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Bailey, J.; Lucas, P. W.; Hough, J. H.; Hirst, E.

    2007-12-01

    Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction indicating the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here. It is also possible that the alignment and the electric field modify dust transport.

  2. 75 FR 64411 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-19

    ... Verification) (65 FR 42122, July 7, 2000, and 68 FR 10784, March 6, 2003); (3) ``Determination of Concentration of Respirable Coal Mine Dust'' (Single Sample) (65 FR 42068, July 7, 2000, and 68 FR 10940 March 6, 2003); and (4) ``Respirable Coal Mine Dust: Continuous Personal Dust Monitor (CPDM)'' (74 FR...

  3. An automatic collector to monitor insoluble atmospheric deposition: application for mineral dust deposition

    NASA Astrophysics Data System (ADS)

    Laurent, B.; Losno, R.; Chevaillier, S.; Vincent, J.; Roullet, P.; Bon Nguyen, E.; Ouboulmane, N.; Triquet, S.; Fornier, M.; Raimbault, P.; Bergametti, G.

    2015-07-01

    Deposition is one of the key terms of the mineral dust cycle. However, dust deposition remains poorly constrained in transport models simulating the atmospheric dust cycle. This is mainly due to the limited number of relevant deposition measurements. This paper aims to present an automatic collector (CARAGA), specially developed to sample the total (dry and wet) atmospheric deposition of insoluble dust in remote areas. The autonomy of the CARAGA can range from 25 days to almost 1 year depending on the programmed sampling frequency (from 1 day to 2 weeks respectively). This collector is used to sample atmospheric deposition of Saharan dust on the Frioul islands in the Gulf of Lions in the Western Mediterranean. To quantify the mineral dust mass in deposition samples, a weighing and ignition protocol is applied. Almost 2 years of continuous deposition measurements performed on a weekly sampling basis on Frioul Island are presented and discussed with air mass trajectories and satellite observations of dust. Insoluble mineral deposition measured on Frioul Island was 2.45 g m-2 for February to December 2011 and 3.16 g m-2 for January to October 2012. Nine major mineral deposition events, measured during periods with significant MODIS aerosol optical depths, were associated with air masses coming from the southern Mediterranean Basin and North Africa.

  4. Mineral dust indirect effects and cloud radiative feedbacks of a simulated idealized nocturnal squall line

    NASA Astrophysics Data System (ADS)

    Seigel, R. B.; van den Heever, S. C.; Saleeby, S. M.

    2013-04-01

    Mineral dust is arguably the most abundant aerosol species in the world and as such potentially plays a large role in aerosol indirect effects (AIEs). This study assesses and isolates the individual responses in a squall line that arise (1) from radiation, (2) from dust altering the microphysics, as well as (3) from the synergistic effects between (1) and (2). To accomplish these tasks, we use the Regional Atmospheric Modeling System (RAMS) set up as a cloud-resolving model (CRM). The CRM contains aerosol and microphysical schemes that allow mineral dust particles to nucleate as cloud drops and ice crystals, replenish upon evaporation and sublimation, be tracked throughout hydrometeor transition, and be scavenged by precipitation and dry sedimentation. Factor separation is used on four simulations of the squall line in order to isolate the individual roles of radiation (RADIATION), microphysically active dust (DUST MICRO), and the nonlinear interactions of those factors (SYNERGY). Results indicate that RADIATION acts to increase precipitation, intensify the cold pool, and enhance the mesoscale organization of the squall line due to changes in microphysics originating from cloud top cooling. Conversely, DUST MICRO decreases precipitation, weakens the cold pool, and weakens the mesoscale organization of the squall line due to an enhancement of the warm rain process. SYNERGY shows little impact on the squall line, except near the freezing level, where an increase in mesoscale organization takes place. The combined effect of the mineral dust AIE due to both DUST MICRO and SYNERGY is to weaken the squall line.

  5. The derivation of estimated dust exposures for U. S. coal miners working before 1970

    SciTech Connect

    Attfield, M.D.; Morring, K. )

    1992-04-01

    A number of reports on the prevalence of coal workers' pneumoconiosis in U.S. coal miners have been published, yet very little is known about the relationship between dust exposure and pneumoconiosis levels in the U.S. This report describes the derivation of cumulative dust exposure estimates by back-extrapolation of data processed by the Mine Safety and Health Administration after 1970 by using a ratio of dust concentrations based on information collected during environmental surveys at certain U.S. mines by the Bureau of Mines between 1968 and 1969. Cumulative personal dust exposure estimates were calculated by using occupational histories obtained from the miners and job-specific estimates of dust concentration. In other reports, the resulting estimated exposures have been shown to correlate well with various measures of respiratory morbidity.

  6. Mineral dust radiative effect on snow in European Alps

    NASA Astrophysics Data System (ADS)

    Di Mauro, Biagio; Fava, Francesco; Ferrero, Luca; Garzonio, Roberto; Baccolo, Giovanni; Delmonte, Barbara; Colombo, Roberto

    2015-04-01

    Mineral Dust (MD) is known to increase the absorption of solar radiation when deposited on snow and ice. This process causes a decrease in the albedo and may enhance snow melting, resulting in a positive radiative forcing (RF) in climate system. The RF from MD on snow can assume high values (~100-200 W/m2) after depositional events altering snow and ice radiative balance and hydrological cycle. In this study, we analyzed a significant MD transport happened during spring in 2014 and in particular its impact on snow optical properties. The dust plume was entrained in the troposphere over the Saharan desert (North African Grand Erg Oriental) during the passage of a cold front, and then transported NE over the Mediterranean by cyclonic atmospheric conditions. MD reached the European Alps where it was deposited by snowfall. We conducted a field proximal sensing survey in 10 plots (2x2 meters) at the Artavaggio plains (Lecco, Italy) with a hyperspectral radiometer (ASD Field-spec pro) collecting reflected radiance of snow in a spectral range between 350 and 2500 nm. Surface snow samples were collected and analyzed in clean room with microparticle counter in order to determine the size distribution and the concentration of MD in each sample. In addition, total mass of insoluble material was also measured by filtering the melted snow. Observed spectra were compared to those simulated by parameterizing the Snow, Ice, and Aerosol Radiation (SNICAR) radiative transfer model with observed variables such as snow grain size, snow density and size distribution of MD. We defined a novel spectral index, the Snow Darkening Index (SDI) to combine red and green wavelengths showing nonlinear correlation with measured MD concentration. Instantaneous radiative forcing was then estimated as the spectral difference between upwelling irradiance of plot containing MD and pure snow plots. MD concentration was up to 107 ppm and total mass of insoluble material up to 325 ppm. Measured RF values

  7. Hf-Nd-Sr isotopic fingerprinting of mineral dust from Asian and North African deserts

    NASA Astrophysics Data System (ADS)

    Ji, J.; Zhao, W.; Balsam, W.

    2015-12-01

    Mineral dust accounts for more than 50% of the atmospheric dust loading and plays an important role in the marine and terrestrial geochemical cycles. The deserts in North Africa, Northern China and Southern Mongolia are the major sources of mineral dust and have been studied intensively over past decades, especially with Sr, Nd and recently Hf isotopes which are seen as powerful tools to identify source areas. However, the isotopic compositions of dust are highly dependent on particle size hindering the ability to accurately identify dust provenance. The clay fraction (<2 μm) comprises about half of all mineral dust and has unique minerals phases dominanted by clay minerals. Once the clay-sized particles are deflated to the upper troposphere, they are transported over long distances and are removed from the atmosphere mainly by wet deposition. Thus, the clay-sized isotopic fingerprints from deserts may be ideal targets not only for tracking the provenance tracing of long-distance transported mineral dust, but also to provide an unparalleled window for understanding the global dust cycle, especially eolian dust preserved in deep-sea sediments and ice cores. In this work we investigate multivariate joint radiogenic Sr, Nd, and Hf isotopic compositions obtained from complete dissolution of clay-sized fractions of surface sediments from Asian and North African deserts. Asian dust source samples included the ten Northern China deserts and sandy lands - the Taklimakan, Gurbantunggut, Qaidam, Badaim Jaran, Tengger and Mu Us deserts, and the Hobq, Hulun Buirm, Onqin Daga and Horqin sandy land - and Mongolian Gobi desert. North African dust samples were from four transects in the Sahara and Sahel from Mali, Togo, Egypt and Morocco . Our results on the clay-sized isotopic measurements of these samples describe (1) the general characteristics of dusts from the Asian with ɛNd from -17.3 to 0.98, ɛHf from -5.95 to 3.68 and 87Sr/86Sr from 0.710113 to 0.73306, and North

  8. Modeling of atmospheric iron processing carried by mineral dust and its deposition to ocean

    NASA Astrophysics Data System (ADS)

    Nickovic, Slobodan; Vukovic, Ana; Vujadinovic, Mirjam

    2014-05-01

    Relatively insoluble iron in dust originating from desert soils increases its solubility after Fe carried by mineral dust is chemically processed by the atmosphere. After dust is deposited deposition to the ocean, soluble Fe as a nutrient could enhance the marine primary production. The atmospheric dust cycle is driven by the atmospheric processes often of smaller, meso-scales. The soil mineralogy of dust emitted from sources determines also how much Fe in the aerosol will be finding. Once Fe is exposed to the atmospheric processes, the atmospheric radiation, clouds and polluted air will chemically affect the iron in dust. Global dust-iron models, having typical horizontal resolutions of 100-300 km which are mostly used to numerically simulate the fate of iron in the atmosphere can provide rather global picture of the dust and iron transport, but not details. Such models often introduce simplistic approximation on the Fe content in dust-productive soils. To simulate the Fe processing we instead implemented a high resolution regional atmospheric dust-iron model with detailed 1km global map for the geographic distribution of Fe content in soil. We also introduced a parameterization of the Fe processing caused by dust mineralogy, cloud processes and solar radiation. We will present results from simulation experiments in order to explore the model capability to reproduce major observed patterns of deposited Fe into the Atlantic cruises.

  9. The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds.

    PubMed

    Atkinson, James D; Murray, Benjamin J; Woodhouse, Matthew T; Whale, Thomas F; Baustian, Kelly J; Carslaw, Kenneth S; Dobbie, Steven; O'Sullivan, Daniel; Malkin, Tamsin L

    2013-06-20

    The amount of ice present in mixed-phase clouds, which contain both supercooled liquid water droplets and ice particles, affects cloud extent, lifetime, particle size and radiative properties. The freezing of cloud droplets can be catalysed by the presence of aerosol particles known as ice nuclei. One of the most important ice nuclei is thought to be mineral dust aerosol from arid regions. It is generally assumed that clay minerals, which contribute approximately two-thirds of the dust mass, dominate ice nucleation by mineral dust, and many experimental studies have therefore focused on these materials. Here we use an established droplet-freezing technique to show that feldspar minerals dominate ice nucleation by mineral dusts under mixed-phase cloud conditions, despite feldspar being a minor component of dust emitted from arid regions. We also find that clay minerals are relatively unimportant ice nuclei. Our results from a global aerosol model study suggest that feldspar ice nuclei are globally distributed and that feldspar particles may account for a large proportion of the ice nuclei in Earth's atmosphere that contribute to freezing at temperatures below about -15 °C.

  10. Integrated approach towards understanding interactions of mineral dust aerosol with warm clouds

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant

    2011-12-01

    Mineral dust is ubiquitous in the atmosphere and represents a dominant type of particulate matter by mass. Dust particles can serve as cloud condensation nuclei (CCN), giant CCN (GCCN), or ice nuclei (IN), thereby, affecting cloud microphysics, albedo, and lifetime. Despite its well-recognized importance, assessments of dust impacts on clouds and climate remain highly uncertain. This thesis addresses the role of dust as CCN and GCCN with the goal of improving our understanding of dust-warm cloud interactions and their representation in climate models. Most studies to date focus on the soluble fraction of aerosol particles when describing cloud droplet nucleation, and overlook the interactions of the hydrophilic insoluble fraction with water vapor. A new approach to include such interactions (expressed by the process of water vapor adsorption) is explored, by combining multilayer Frenkel-Halsey-Hill (FHH) physical adsorption isotherm and curvature (Kelvin) effects. The importance of adsorption activation theory (FHH-AT) is corroborated by measurements of CCN activity of mineral aerosols generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. A new aerosol generation setup for CCN measurements was developed based on a dry generation technique capable of reproducing natural dust aerosol emission. Based on the dependence of critical supersaturation with particle dry diameter, it is found that the FHH-AT is a better framework for describing fresh (and unprocessed) dust CCN activity than the classical Kohler theory (KT). Ion Chromatography (IC) measurements performed on fresh regional dust samples indicate negligible soluble fraction, and support that water vapor adsorption is the prime source of CCN activity in the dust. CCN measurements with the commonly used wet generated mineral aerosol (from atomization of a dust aqueous suspension) are also carried out. Results indicate that the method is subject

  11. Alignment of atmospheric mineral dust due to electric field

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Bailey, J.; Lucas, P. W.; Hough, J. H.; Hirst, E.

    2007-09-01

    Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction consistent with the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling also indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here.

  12. Radiative Effect of Saharan Mineral Dust on the Nonlinear Dynamics of African Easterly Waves

    NASA Astrophysics Data System (ADS)

    Grogan, D.; Nathan, T. R.; Chen, S. H.

    2014-12-01

    The radiative effects of Saharan mineral dust aerosols on the nonlinear dynamics of African easterly waves (AEWs) are examined using the Weather Research and Forecasting Dust (WRFD) model. The WRFD model is governed by the Advanced Research WRF dynamical core, and continuity equations for twelve dust particle sizes that represent the spectrum of mineral dust aerosols observed in the atmosphere. To incorporate dust radiative effects in the model, aerosol optical properties (i.e. optical depth, single scattering albedo, and asymmetric parameters) for all dust sizes are inputted into the shortwave and longwave radiation schemes. By choosing zonal-mean distributions of zonal wind and temperature that are consistent with summer over Northwest Africa, idealized dry simulations explore the nonlinear behavior of AEWs in the presence of dust. The initial zonal-mean dust fields are represented as simple distributions that vary in structure and concentration, which are consistent with observed dust events over Africa. Specific AEW features investigated in the simulations include the evolution of wave energy, Eliassen-Palm fluxes, and spatial structures. Among the questions to be addressed are the following: How does the concentration and spatial distribution of the dust field affect the strength and timing of AEW amplitude saturation? What impact will the dust induced wave fluxes have on the horizontal or vertical shear of the zonal-mean AEJ? Does the interaction between the AEJ, AEW and dust affect the timing and location of the AEW trough, and thus the formation of critical latitudes? Answers to these questions will aid in the understanding and forecasting of AEWs, and their possible subsequent development into tropical storms.

  13. New mineral dust record from the TALDICE ice core (East Antarctica)

    NASA Astrophysics Data System (ADS)

    Maggi, V.; Delmonte, B.; Albani, S.; Mazzola, C.

    2010-12-01

    Aeolian mineral dust is an active component of the climate system, interacting both directly and indirectly with radiation and biogeochemistry. Its deposition and stratigraphical preservation in appropriate environmental setting leaves deposits that once dated can be used as paleoclimate proxies. In particular dust records from ice cores can provide insights into past variations of environmental conditions at the dust source areas, atmospheric circulation, the hydrological cycle at source and deposition sites and dust deposition mechanisms. Here we present the new dust record from the 1620 m deep TALDICE ice core, drilled at Talos Dome (159°11' E, 72°49' S, 2315 m A.S.L.), on the edge of the East Antarctic plateau, about 290 km from the Southern Ocean and 250 km from the Ross Sea. We analysed variations in dust concentration, depositional flux, size distributions and geochemical fingerprint. The TALDICE dust records confirms the major findings from previous ice core studies in terms of the big glacial/interglacial variations in dust deposition, thanks to the relatively high accumulation rate and good dating. We also show new peculiar aspects emerging for this record, such as the importance of Antarctic sources for dust for this peripheral sites and the relation between variations in dust deposition during the deglaciation and the Holocene to variations in the atmospheric circulation in the Ross Sea.

  14. Laboratory investigations of mineral dust near-backscattering depolarization ratios

    NASA Astrophysics Data System (ADS)

    Järvinen, E.; Kemppinen, O.; Nousiainen, T.; Kociok, T.; Möhler, O.; Leisner, T.; Schnaiter, M.

    2016-07-01

    Recently, there has been increasing interest to derive the fractions of fine- and coarse-mode dust particles from polarization lidar measurements. For this, assumptions of the backscattering properties of the complex dust particles have to be made either by using empirical data or particle models. Laboratory measurements of dust backscattering properties are important to validate the assumptions made in the lidar retrievals and to estimate their uncertainties. Here, we present laboratory measurements of linear and circular near-backscattering (178°) depolarization ratios of over 200 dust samples measured at 488 and 552 nm wavelengths. The measured linear depolarization ratios ranged from 0.03 to 0.36 and were strongly dependent on the particle size. The strongest size-dependence was observed for fine-mode particles as their depolarization ratios increased almost linearly with particle median diameter from 0.03 to 0.3, whereas the coarse-mode particle depolarization values stayed rather constant with a mean linear depolarization ratio of 0.27. The depolarization ratios were found to be insensitive to the dust source region or thin coating of the particles or to changes in relative humidity. We compared the measurements with results of three different scattering models. With certain assumptions for model particle shape, all the models were capable of correctly describing the size-dependence of the measured dust particle, albeit the model particles significantly differed in composition, shape and degree of complexity. Our results show potential for distinguishing the dust fine- and coarse-mode distributions based on their depolarization properties and, thus, can serve the lidar community as an empirical reference.

  15. Atmospheric processing outside clouds increases soluble iron in mineral dust.

    PubMed

    Shi, Zongbo; Krom, Michael D; Bonneville, Steeve; Benning, Liane G

    2015-02-01

    Iron (Fe) is a key micronutrient regulating primary productivity in many parts of the global ocean. Dust deposition is an important source of Fe to the surface ocean, but most of this Fe is biologically unavailable. Atmospheric processing and reworking of Fe in dust aerosol can increase the bioavailable Fe inputs to the ocean, yet the processes are not well understood. Here, we experimentally simulate and model the cycling of Fe-bearing dust between wet aerosol and cloud droplets. Our results show that insoluble Fe in dust particles readily dissolves under acidic conditions relevant to wet aerosols. By contrast, under the higher pH conditions generally relevant to clouds, Fe dissolution tends to stop, and dissolved Fe precipitates as poorly crystalline nanoparticles. If the dust-bearing cloud droplets evaporated again (returning to the wet aerosol stage with low pH), those neo-formed Fe nanoparticles quickly redissolve, while the refractory Fe-bearing phases continue to dissolve gradually. Overall, the duration of the acidic, wet aerosol stage ultimately increases the amount of potentially bioavailable Fe delivered to oceans, while conditions in clouds favor the formation of Fe-rich nanoparticles in the atmosphere.

  16. 76 FR 2617 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Mine...' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors AGENCY: Mine Safety and.... SUMMARY: The Mine Safety and Health Administration (MSHA) is extending the comment period on the...

  17. 75 FR 73995 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-30

    ..., 2010, MSHA announced that it would hold six public hearings on the proposed rule (75 FR 69617). Due to... the proposed rule on October 19, 2010 (75 FR 64412); it is available on MSHA's Web site at http://www...' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors AGENCY: Mine Safety...

  18. Pulmonary function of U. S. coal miners related to dust exposure estimates

    SciTech Connect

    Attfield, M.D.; Hodous, T.K. )

    1992-03-01

    This study of 7,139 U.S. coal miners used linear regression analysis to relate estimates of cumulative dust exposure to several pulmonary function variables measured during medical examinations undertaken between 1969 and 1971. The exposure data included newly derived cumulative dust exposure estimates for the period up to time of examination based on large data bases of underground airborne dust sampling measurements. Negative associations were found between measures of cumulative exposure and FEV1, FVC, and the FEV1/FVC ratio (p less than 0.001). In general, the relationships were similar to those reported for British coal miners. Overall, the results demonstrate an adverse effect of coal mine dust exposure on pulmonary function that occurs even in the absence of radiographically detected pneumoconiosis.

  19. Predicting the Mineral and Chemical Composition of Dust Aerosols: Evaluation and Implications

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2014-12-01

    Soil dust aerosols in Earth system models are typically assumed to have globally uniform properties. However, important climate processes related to dust depend on the aerosol mineral and chemical composition, which varies regionally. Such processes include aerosol radiative forcing, transport of bioavailable iron that catalyzes marine photosynthesis, heterogeneous chemistry, ice nucleation, and cloud condensation.We have implemented a new version of the soil dust aerosol scheme in the NASA GISS Earth System ModelE that takes into account the mineral composition of the dust particles. Dust aerosols are represented as an external mixture of minerals such as illite, kaolinite, smectite, carbonates, quartz, feldspar and gypsum, as well as iron oxides and accretions of iron oxides with each of the these minerals.We present a new publically available compilation of measurements of mineral fractions derived from ca. 50 references from the literature. This compilation is used to evaluate our new model of mineral and elemental composition within ModelE. We discuss the challenges of comparing simulated mineral fractions to measurements, which often come from field campaigns and ship cruises of limited duration. Despite uncertainties of the measurements, we show the importance of estimating the undisturbed size distribution of the parent soil prior to wet sieving, along with the modification of this size distribution during emission. In particular, our new model reproduces measurements showing greater amount of aerosols at silt sizes (whose diameters exceed 2 μm) including significant amounts of clay mineral aerosols (like illite) at silt sizes. Our model also reduces the systematic overestimation of quartz, while allowing iron to be transported farther from its source as impurities than in its pure, crystalline form.

  20. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    DOE PAGES

    Zhang, Y.; Mahowald, N.; Scanza, R.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J.; Zhuang, G.; Chen, Y.; Cohen, D. D.; et al

    2014-12-17

    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 Camore » / 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.« less

  1. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Mahowald, N.; Scanza, R.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J.; Zhuang, G.; Chen, Y.; Cohen, D. D.; Paytan, A.; Patey, M. D.; Achterberg, E. P.; Engelbrecht, J. P.; Fomba, K. W.

    2014-12-01

    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.

  2. Modeling of mineral dust in the atmosphere: Sources, transport, and optical thickness

    NASA Technical Reports Server (NTRS)

    Tegen, Ina; Fung, Inez

    1994-01-01

    A global three-dimensional model of the atmospheric mineral dust cycle is developed for the study of its impact on the radiative balance of the atmosphere. The model includes four size classes of minearl dust, whose source distributions are based on the distributions of vegetation, soil texture and soil moisture. Uplift and deposition are parameterized using analyzed winds and rainfall statistics that resolve high-frequency events. Dust transport in the atmosphere is simulated with the tracer transport model of the Goddard Institute for Space Studies. The simulated seasonal variations of dust concentrations show general reasonable agreement with the observed distributions, as do the size distributions at several observing sites. The discrepancies between the simulated and the observed dust concentrations point to regions of significant land surface modification. Monthly distribution of aerosol optical depths are calculated from the distribution of dust particle sizes. The maximum optical depth due to dust is 0.4-0.5 in the seasonal mean. The main uncertainties, about a factor of 3-5, in calculating optical thicknesses arise from the crude resolution of soil particle sizes, from insufficient constraint by the total dust loading in the atmosphere, and from our ignorance about adhesion, agglomeration, uplift, and size distributions of fine dust particles (less than 1 micrometer).

  3. Atmospheric transport and deposition of mineral dust to the ocean: implications for research needs.

    PubMed

    Schulz, Michael; Prospero, Joseph M; Baker, Alex R; Dentener, Frank; Ickes, Luisa; Liss, Peter S; Mahowald, Natalie M; Nickovic, Slobodan; García-Pando, Carlos Pérez; Rodríguez, Sergio; Sarin, Manmohan; Tegen, Ina; Duce, Robert A

    2012-10-01

    This paper reviews our knowledge of the measurement and modeling of mineral dust emissions to the atmosphere, its transport and deposition to the ocean, the release of iron from the dust into seawater, and the possible impact of that nutrient on marine biogeochemistry and climate. Of particular concern is our poor understanding of the mechanisms and quantities of dust deposition as well as the extent of iron solubilization from the dust once it enters the ocean. Model estimates of dust deposition in remote oceanic regions vary by more than a factor of 10. The fraction of the iron in dust that is available for use by marine phytoplankton is still highly uncertain. There is an urgent need for a long-term marine atmospheric surface measurement network, spread across all oceans. Because the southern ocean is characterized by large areas with high nitrate but low chlorophyll surface concentrations, that region is particularly sensitive to the input of dust and iron. Data from this region would be valuable, particularly at sites downwind from known dust source areas in South America, Australia, and South Africa. Coordinated field experiments involving both atmospheric and marine measurements are recommended to address the complex and interlinked processes and role of dust/Fe fertilization on marine biogeochemistry and climate.

  4. Selenium and exposure to fibrogenic mineral dust: a mini-review.

    PubMed

    Muzembo, Basilua Andre; Deguchi, Yoji; Ngatu, Nlandu Roger; Eitoku, Masamitsu; Hirota, Ryoji; Suganuma, Narufumi

    2015-04-01

    Individuals exposed to fibrogenic mineral dust may exhibit an impaired antioxidant system and produce high levels of reactive oxygen and nitrogen species through immune cells, contributing to the perturbation of immune cell function, inflammation, fibrosis and lung cancer. The lung diseases which are caused by inhalation of fibrogenic mineral dust, known as pneumoconioses, develop progressively and irreversibly over decades. At the moment there is no known cure. The trace element selenium has potent antioxidant and anti-inflammatory properties mediated mainly through selenoproteins. Research has demonstrated that selenium has the ability to protect against cardiovascular diseases; to kill cancer cells in vitro and reduce cancer incidence; and to immunomodulate various cellular signaling pathways. For these reasons, selenium has been proposed as a promising therapeutic agent in oxidative stress associated pathology that in theory would be beneficial for the prevention or treatment of pneumoconioses such as silicosis, asbestosis, and coal worker's pneumoconiosis. However, studies regarding selenium and occupational lung diseases are rare. The purpose of this study is to conduct a mini-review regarding the relationship between selenium and exposure to fibrogenic mineral dust with emphasis on epidemiological studies. We carried out a systematic literature search of English published studies on selenium and exposure to fibrogenic mineral dust. We found four epidemiological studies. Reviewed studies show that selenium is lower in individuals exposed to fibrogenic mineral dust. However, three out of the four reviewed studies could not confirm cause-and-effect relationships between low selenium status and exposure to fibrogenic mineral dust. This mini-review underscores the need for large follow-up and mechanistic studies for selenium to further elucidate its therapeutic effects.

  5. Sensitivity Study of Cross-Atlantic Dust Transport to Dust Emissions, Chemical Aging and Removal Processes and Comparison with Ground and Satellite Data

    NASA Astrophysics Data System (ADS)

    Abdelkader, Mohamed; Metzger, Swen; Klingmüller, Klaus; Steil, Benedikt; Lelieveld, Jos

    2016-04-01

    Representing transatlantic dust transport is one of the challenges in climate modeling and of key importance, because of its large impact on the Earth's radiation budget. Desert dust, emitted from the Sahara, is regularly transported westwards across the Atlantic Ocean towards the Caribbean. The balance between emissions and removal processes, as well as the manifold chemical reactions control the impact of dust on the atmospheric composition and the interaction of dust with climate change. During transatlantic transport, dust undergoes chemical aging, which involves various heterogeneous reactions that strongly depend on the mineral composition of dust (alkalinity), the surface chemistry and the associated aerosol water uptake. In this study, different parameters affecting the long-range dust transport are studied with the atmospheric chemistry-climate model EMAC. We consider chemical speciation of primary sea salt and dust particles and account for major cations (Na+, K+, Mg2+, Ca2) and anions (Cl-, SO42-, HSO4-), calculated online with meteorology, i.e., feeding back onto precipitation and changing surface wind speed and roughness. We resolve the chemical aging of primary particles through explicit neutralization reactions of the cations and anions with major oxidation products (H2SO4, HNO3, HCl, NH3) from natural and anthropogenic air pollution sources, which can condense on the particles surface during long-range transport and undergo gas-liquid-solid aerosol partitioning, depending on the concentration level of emissions and the transport processes of the primary and secondary aerosols and their precursor gases. Comprehensive analysis of the different parameters affecting the long-range transport, which include the emission flux and particle size distributions, aging mechanism, convection scheme, wet and dry scavenging, show a strong dependence of the dust concentration and optical properties over the Caribbean mainly on the chemical aging of dust during long

  6. Sensitivity Study of Cross-Atlantic Dust Transport to Dust Emissions, Chemical Aging and Removal Processes and Comparison with Ground and Satellite Data

    NASA Astrophysics Data System (ADS)

    Mohamed, A.; Metzger, S. M.; Klingmüller, K.; Lelieveld, J.

    2015-12-01

    Representing trans-Atlantic dust transport is one of the challenges in climate modeling and of key importance, because of its large impact on the Earth's radiation budget. Desert dust, emitted from the Sahara, is regularly transported westwards across the Atlantic Ocean towards the Caribbean. The balance between emissions and removal processes, as well as the manifold chemical reactions control the impact of dust on the atmospheric composition and the interaction of dust with climate change. During trans-Atlantic transport, dust undergoes chemical aging, which involves various heterogeneous reactions that strongly depend on the mineral composition of dust (alkalinity), the surface chemistry and the associated aerosol water uptake. In this study, different parameters affecting the long-range dust transport are studied with the atmospheric chemistry-climate model EMAC. We consider chemical speciation of primary sea salt and dust particles and account for major cations (Na+, K+, Mg2+, Ca2) and anions (Cl-, SO42-, HSO4-), calculated online with meteorology, i.e., feeding back onto precipitation and changing surface wind speed and roughness. We resolve the chemical aging of primary particles through explicit neutralization reactions of the cations and anions with major oxidation products (H2SO4, HNO3, HCl, NH3) from natural and anthropogenic air pollution sources, which can condense on the particles surface during long-range transport and undergo gas-liquid-solid aerosol partitioning, depending on the concentration level of emissions and the transport processes of the primary and secondary aerosols and their precursor gases. Comprehensive analysis of the different parameters affecting the long-range transport, which include the emission flux and particle size distributions, aging mechanism, convection scheme, wet and dry scavenging, show a strong dependence of the dust concentration and optical properties over the Caribbean mainly on the chemical aging of dust during

  7. A Theoretical Framework for Understanding the Effects of Saharan Mineral Dust Aerosols on African Easterly Waves

    NASA Astrophysics Data System (ADS)

    Nathan, T. R.; Grogan, D.; Chen, S.

    2013-12-01

    Studies have shown that a large fraction of the intense hurricanes observed over the Atlantic Ocean originate as African easterly waves (AEWs). Of the many processes that affect the propagation, growth and structure of AEWs, the effects of Saharan mineral dust aerosols on AEWs remains an outstanding scientific problem. With this in mind, a new theoretical framework is presented that illuminates causal relationships between Saharan dust and the linear dynamics of AEWs. The framework is built on a quasi-geostrophic system governed by coupled equations for potential vorticity, temperature, and dust continuity. The radiative-dust heating rate accounts for both shortwave and longwave radiative transfer. The source of dust is due to surface emission, which depends on surface wind; the sinks of dust are due to sedimentation and dry deposition. A perturbation analysis yields analytical expressions for the propagation and growth characteristics of the model's AEWs. These expressions are functions of vertically and meridionally averaged wave activity, which depends on wave spatial structure, dust-radiative heating, and the background distributions of wind, temperature, and dust mixing ratio. More specifically, the propagation and growth of the AEWs depend on the amount of dust lofted from the surface by the wind, and the meridional and vertical gradients of the basic state dust distribution, which are modulated by the Doppler-shifted frequency. Idealized cases are presented that show the effects of Saharan dust on the propagation, group velocity, growth, structure, and wave fluxes of AEWs. The clarity of the expressions connecting dust aerosols to the linear properties of AEWs provides an important interpretive tool for analyzing results obtained from comprehensive model simulations of AEWs, such as those produced by the Weather Research and Forecasting (WRF) model.

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

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Leung, Lai-Yung R.; Johnson, Ben; McFarlane, Sally A.; Gustafson, William I.; Fast, Jerome D.; Easter, Richard C.

    2010-09-20

    A fully coupled meteorology-chemistry-aerosol model (WRF-Chem) with the implementation of two dust emission schemes (GOCART and DUSTRAN) into two aerosol models (MADE/SORGAM and MOSAIC) is applied over North Africa to investigate the modeling sensitivities to dust emissions and aerosol size treatments in simulating mineral dust and its shortwave (SW) radiative forcing. Model results of the spatial distribution of mineral dust and its radiative forcing are evaluated using measurements from the AMMA SOP0 campaign in January and February of 2006 over North Africa. Our study suggests that the size distribution of emitted dust can result in significant differences (up to 100%) in simulating mineral dust and its SW radiative forcing. With the same dust emission and dry deposition processes, two aerosol models, MADE/SORGAM and MOSAIC, can yield large difference in size distributions of dust particles due to their different aerosol size treatments using modal and sectional approaches respectively. However, the difference between the two aerosol models in simulating the mass concentrations and the SW radiative forcing of mineral dust is small (< 10%). The model simulations show that mineral dust increases AOD by a factor of 2, heats the lower atmosphere (1-3 km) with a maximum rate of 0.7±0.5 K day-1 below 1 km, and reduces the downwelling SW radiation by up to 25 W m-2 on 24-hour average at surface, highlighting the importance of including dust radiative impact in understanding the regional climate of North Africa. When compared to the available measurements, WRF-Chem simulations can generally capture the measured features of mineral dust and its radiative properties over North Africa, suggesting that the model can be used to perform more extensive simulations of regional climate over North Africa.

  9. Clays as mineral dust aerosol: An integrated approach to studying climate, atmospheric chemistry, and biogeochemical effects of atmospheric clay minerals in an undergraduate research laboratory

    NASA Astrophysics Data System (ADS)

    Hatch, C. D.; Crane, C. C.; Harris, K. J.; Thompson, C. E.; Miles, M. K.; Weingold, R. M.; Bucuti, T.

    2011-12-01

    Entrained mineral dust aerosol accounts for 45% of the global annual atmospheric aerosol load and can have a significant influence on important environmental issues, including climate, atmospheric chemistry, cloud formation, biogeochemical processes, visibility, and human health. 70% of all mineral aerosol mass originating from Africa consists of layered aluminosilicates, including illite, kaolinite, and montmorillonite clays. Clay minerals are a largely neglected component of mineral aerosol, yet they have unique physiochemical properties, including a high reactive surface area, large cation exchange capacities, small particle sizes, and a relatively large capacity to take up adsorbed water, resulting in expansion of clay layers (and a larger reactive surface area for heterogeneous interactions) in some cases. An integrated laboratory research approach has been implemented at Hendrix College, a Primarily Undergraduate Institution, in which undergraduate students are involved in independent and interdisciplinary research projects that relate the chemical aging processes (heterogeneous chemistry) of clay minerals as a major component of mineral aerosol to their effects on climate (water adsorption), atmospheric chemistry (trace gas uptake), and biogeochemistry (iron dissolution and phytoplankton biomarker studies). Preliminary results and future directions will be reported.

  10. Optical, physical and chemical properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Di Biagio, Claudia; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Loisil, Rodrigue; Triquet, Sylvain; Zapf, Pascal; Roberts, Greg; Bourrianne, Thierry; Torres, Benjamin; Blarel, Luc; Sellegri, Karine; Freney, Evelyn; Schwarzenbock, Alfons; Ravetta, François; Laurent, Benoit; Mallet, Marc; Formenti, Paola

    2014-05-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), two intensive airborne campaigns (TRAQA, TRansport and Air QuAlity, 18 June - 11 July 2012, and ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) have been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to

  11. Properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Triquet, Sylvain; Zapf, Pascal; Loisil, Rodrigue; Bourrianne, Thierry; Freney, Evelyn; Dupuy, Regis; Sellegri, Karine; Schwarzenbock, Alfons; Torres, Benjamin; Mallet, Marc; Cassola, Federico; Prati, Paolo; Formenti, Paola

    2015-04-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), one intensive airborne campaign (ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) has been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to the dust origin and transport. Case studies of dust transport

  12. Characterization of minerals in air dust particles in the state of Tamilnadu, India through ftir spectroscopy

    NASA Astrophysics Data System (ADS)

    Senthil Kumar, R.; Rajkumar, P.

    2013-08-01

    The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively.

  13. Global Modeling of Mineral Dust and its Optical Thickness

    NASA Technical Reports Server (NTRS)

    Ginoux, Paul A.; Chin, Mian; Tegen, Ina; Herman, Jay R.; Torres, Omar; Winker, David; Holben, Brent; Lin, S.-J.

    1999-01-01

    Global distribution of dust in the atmosphere has been simulated using the NASA Goddard chemical transport model (GEOS-CTM) to help retrieve the aerosol optical thickness from TOMS absorbing aerosol index. The model contains a dust module which accounts for sources and removal processes. The transport is driven by the assimilated meteorological fields generated by the NASA Goddard Earth Observing System Data Assimilation System (GEOS DAS). One of the key parameters, in the retrieval algorithm of optical thickness from Total Ozone Mapping Spectrometer (TOMS) data, is the vertical profile of aerosols. During the period 10- 19 September 1994, Lidar on-space Technology Experiment (LITE) was flown on space shuttle Discovery. The 53 hours of data collected cover the lower atmosphere from the earth surface to 20 kilometers altitude and from 57 N to 57 S with a high resolution of about 15 meters. The model results are compared with LITE data over the source regions of dust (Africa, Middle East, Asia, Australia) and in the remote troposphere (Atlantic and Pacific). The simulated horizontal distribution is compared with TOMS absorbing aerosol index. Finally the calculated optical thickness will be assessed with ground based sun-photometers (AERONET).

  14. Assessing sources of airborne mineral dust and other aerosols, in Iraq

    NASA Astrophysics Data System (ADS)

    Engelbrecht, Johann P.; Jayanty, R. K. M.

    2013-06-01

    Most airborne particulate matter in Iraq comes from mineral dust sources. This paper describes the statistics and modeling of chemical results, specifically those from Teflon® filter samples collected at Tikrit, Balad, Taji, Baghdad, Tallil and Al Asad, in Iraq, in 2006/2007. Methodologies applied to the analytical results include calculation of correlation coefficients, Principal Components Analysis (PCA), and Positive Matrix Factorization (PMF) modeling. PCA provided a measure of the covariance within the data set, thereby identifying likely point sources and events. These include airborne mineral dusts of silicate and carbonate minerals, gypsum and salts, as well as anthropogenic sources of metallic fumes, possibly from battery smelting operations, and emissions of leaded gasoline vehicles. Five individual PMF factors (source categories) were modeled, four of which being assigned to components of geological dust, and the fifth to gasoline vehicle emissions together with battery smelting operations. The four modeled geological components, dust-siliceous, dust-calcic, dust-gypsum, and evaporate occur in variable ratios for each site and size fraction (TSP, PM10, and PM2.5), and also vary by season. In general, Tikrit and Taji have the largest and Al Asad the smallest percentages of siliceous dust. In contrast, Al Asad has the largest proportion of gypsum, in part representing the gypsiferous soils in that region. Baghdad has the highest proportions of evaporite in both size fractions, ascribed to the highly salinized agricultural soils, following millennia of irrigation along the Tigris River valley. Although dust storms along the Tigris and Euphrates River valleys originate from distal sources, the mineralogy bears signatures of local soils and air pollutants.

  15. Systematic Relationships Between Lidar Observables And Sizes And Mineral Composition Of Dust Aerosols

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Perlwitz, J. P.; Fridlind, A. M.; Chowdhary, J.; Cairns, B.; Stangl, A. J.

    2015-12-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  16. Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

    2015-01-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  17. Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations

    NASA Astrophysics Data System (ADS)

    Ryder, C. L.; McQuaid, J. B.; Flamant, C.; Washington, R.; Brindley, H. E.; Highwood, E. J.; Marsham, J. H.; Parker, D. J.; Todd, M. C.; Banks, J. R.; Brooke, J. K.; Engelstaedter, S.; Estellés, V.; Formenti, P.; Garcia-Carreras, L.; Kocha, C.; Marenco, F.; Rosenberg, P.; Sodemann, H.; Allen, C. J. T.; Bourdon, A.; Bart, M.; Cavazos-Guerra, C.; Chevaillier, S.; Crosier, J.; Darbyshire, E.; Dean, A. R.; Dorsey, J. R.; Kent, J.; O'Sullivan, D.; Schepanski, K.; Szpek, K.; Woolley, A.

    2015-01-01

    The Fennec climate program aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE Falcon 20 is described, with specific focus on instrumentation specially developed and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include: (1) the first airborne measurement of dust particles sized up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in-situ observations of processes in SABL clouds showing dust acting as CCN and IN at -15 °C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold-pool (haboob) issued from deep convection over the Atlas, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area measurements suggest coarser particles provide a route for ozone depletion, (9) discrepancies between airborne coarse mode size distributions and AERONET sunphotometer retrievals under

  18. Health effects of mineral dusts, Volume 28: Proceedings

    SciTech Connect

    Guthrie, G.D. Jr.; Mossman, B.T.

    1993-12-31

    The processes that lead to the development of disease (or pathogenesis) by minerals very likely occur at or near the mineral-fluid interface. Thus the field of ``mineral-induced pathogenesis`` is a prime candidate for interdisciplinary research, involving mineral scientists, health scientists, petrologists, pathologists, geochemists, biochemists, and surface scientists, to name a few. This review volume and the short course upon which it was based are intended to provide some of the necessary tools for the researcher interested in this area of interdisciplinary research. The chapters present several of the important problems, concepts, and approaches from both the geological and biological ends of the spectrum. These two extremes are partially integrated throughout the book by cross-referencing between chapters. Chapter 1 also presents a general introduction into the ways in which these two areas overlap. The final chapter of this book discusses some of the regulatory aspects of minerals. A glossary is included at the end of this book, because the complexity of scientific terms in the two fields can thwart even the most enthusiastic of individuals. Individual reports have been processed separately for the database.

  19. Understanding ice nucleation characteristics of selective mineral dusts suspended in solution

    NASA Astrophysics Data System (ADS)

    Kumar, Anand; Marcolli, Claudia; Kaufmann, Lukas; Krieger, Ulrich; Peter, Thomas

    2016-04-01

    Introduction & Objectives Freezing of liquid droplets and subsequent ice crystal growth affects optical properties of clouds and precipitation. Field measurements show that ice formation in cumulus and stratiform clouds begins at temperatures much warmer than those associated with homogeneous ice nucleation in pure water, which is ascribed to heterogeneous ice nucleation occurring on the foreign surfaces of ice nuclei (IN). Various insoluble particles such as mineral dust, soot, metallic particles, volcanic ash, or primary biological particles have been suggested as IN. Among these the suitability of mineral dusts is best established. The ice nucleation ability of mineral dust particles may be modified when secondary organic or inorganic substances are accumulating on the dust during atmospheric transport. If the coating is completely wetting the mineral dust particles, heterogeneous ice nucleation occurs in immersion mode also below 100 % RH. A previous study by Kaufmann (PhD Thesis 2015, ETHZ) with Hoggar Mountain dust suspensions in various solutes (ammonium sulfate, PEG, malonic acid and glucose) showed reduced ice nucleation efficiency (in immersion mode) of the particles. Though it is still quite unclear of how surface modifications and coatings influence the ice nucleation activity of the components present in natural dust samples. In view of these results we run freezing experiments using a differential scanning calorimeter (DSC) with the following mineral dust particles suspended in pure water and ammonium sulfate solutions: Arizona Test Dust (ATD), microcline, and kaolinite (KGa-2, Clay Mineral Society). Methodology Suspensions of mineral dust samples (ATD: 2 weight%, microcline: 5% weight, KGa-2: 5% weight) are prepared in pure water with varying solute concentrations (ammonium sulfate: 0 - 10% weight). 20 vol% of this suspension plus 80 vol% of a mixture of 95 wt% mineral oil (Aldrich Chemical) and 5 wt% lanolin (Fluka Chemical) is emulsified with a

  20. Light-Induced SO2 Photochemistry at the Mineral Dust Surface

    NASA Astrophysics Data System (ADS)

    Styler, S. A.; Doussin, J.; Formenti, P.; Donaldson, D.

    2013-12-01

    The uptake of SO2 by mineral dust is believed to proceed first by formation of surface-bound sulfite, which can subsequently be oxidized to sulfate not only by co-sorbed O3 and NO2 but also by photooxidants such as Fe and Ti present within the dust itself. In the first phase of this study, we investigated the effect of light upon SO2 uptake by Fe2O3, TiO2, illite, feldspar, and mineral dust samples obtained from Niger, Tunisia, and China. We determined the initial uptake coefficient of SO2 at the surface of dust samples under both light and dark conditions using a photochemical Knudsen cell, and then measured the relative quantities of sulfite and sulfate formed at the surface of these films using ion chromatography. In the second phase of this study, which was performed in the CESAM atmospheric chamber, we explored the possibility that light-induced production of surface-sorbed sulfate might result in enhanced dust hygroscopicity by measuring changes in dust particle size distribution as a function of exposure to SO2 and light under a range of relative humidity conditions.

  1. Atmospheric mineral dust in dryland ecosystems: Applications of environmental magnetism

    NASA Astrophysics Data System (ADS)

    Reynolds, Richard L.; Goldstein, Harland L.; Miller, Mark E.

    2010-07-01

    Magnetic properties of shallow (<10-cm depth), fine-grained surficial sediments contrast greatly with those of immediately underlying bedrock across much of the dry American Southwest. At 26 study sites in fine-grained (<63 μm) surficial sediments isolated from alluvial inputs, isothermal remanent magnetization (IRM; mean of 67 samples = 6.72 × 10-3 Am2 kg-1) is more than two orders of magnitude greater than that for underlying Paleozoic and Mesozoic sedimentary rocks. This contrast is mainly caused by the presence of silt-size, titanium-bearing magnetite particles in the surficial deposits and their absence in bedrock. Because of their size, composition, and isolated location, the magnetite particles represent a component of atmospheric dust likely deposited over the past few centuries. The positive correlation of sediment-IRM values with amounts of potential plant nutrients reveals the importance of atmospheric dust to soil fertility over much of the American Southwest. Subsequent disturbance of landscapes, by domestic livestock grazing as an example, commonly results in wind erosion, which then depletes exposed surfaces of original aeolian magnetite and associated fine-grained sediment. Declines in soil fertility and water-holding capacity in these settings can be estimated in some field settings via decreases in magnetic susceptibility, relative to nearby undisturbed areas. Along gentle hillslope gradients of the Colorado Plateau, field measures for aeolian magnetite demonstrate that the redistribution of deposited atmospheric dust influences landscape-level patterns in the distribution of invasive exotic plant species. Our results indicate that environmental magnetism has high potential for assessing the development and degradation of dry landscapes elsewhere.

  2. Mineral phases and metals in baghouse dust from secondary aluminum production

    EPA Science Inventory

    Baghouse dust (BHD) is a solid waste generated by air pollution control systems during secondary aluminum processing (SAP). Management and disposal of BHD can be challenging in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 78...

  3. Mineral Dust Impact on Short- and Long-Wave Radiation and Comparison with Ceres Measurements

    NASA Astrophysics Data System (ADS)

    Romano, Salvatore; Perrone, Maria Rita

    2016-06-01

    Clear-sky downward and upward radiative flux measurements both in the short- and in the long-wave spectral range have been used to estimate and analyze the radiation changes at the surface due to the mineral dust advection at a Central Mediterranean site. Then, short- and long-wave radiative fluxes retrieved from the CERES (Clouds and the Earth's Radiant Energy System) radiometer sensors operating on board the EOS (Earth Observing System) AQUA and TERRA platforms have been used to evaluate the mineral dust radiative impact at the top of the atmosphere. Satellite-derived radiative fluxes at the surface have been compared with corresponding ground-based flux measurements, collocated in space and time, to better support and understand the desert dust radiative impact. Results referring to the year 2012 are reported.

  4. [Effect of water sprinkling on total dust and mineral fiber concentration during serpentine asbestos processing].

    PubMed

    Woźniak, H; Wiecek, E; Pelc, W; Dobrucka, D; Opalska, B

    1993-01-01

    By means of personal air sampler and Fibre Monitor FM-7400 concentrations of total dust and respirable mineral fibre were measured at work-posts, after sprinkling places with the highest emission of dust, in the plant where serpentine asbestos, used as road stone, was processed. It was found that due to sprinkling mean concentrations of total dust during a shift decreased by 1.5 (at inspection post) to 13.5 times at the post where crushing and sorting machines were served (before sprinkling -29.7 mg/m3 and after 2.2 mg/m3). It was found, at the same time, that sprinkling no decreased the concentration of mineral fibres.

  5. How important are cyclones for emitting mineral dust aerosol in North Africa?

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Schepanski, K.; Knippertz, P.; Heinold, B.; Tegen, I.

    2013-12-01

    This study presents the first quantitative estimate of the mineral dust emission associated to atmospheric depressions and migrating, long-lived cyclones in North Africa. Results from a tracking algorithm are combined with dust emission flux calculations based on ERA-Interim data from the European Centre for Medium-Range Weather Forecasts for 1989-2008. The results highlight that depressions are abundant and associated with 55% of the dust emission amount annually and spatially averaged over North African dust sources. Even larger contributions to dust emission from depressions are found south of the Atlas Mountains during spring with regionally up to 90%. It is spring when the largest monthly totals of 250-380 g m-2 of dust emission occur in North Africa. The remaining months have a total dust emission smaller than 80 g m-2. In summer, depressions, particularly Saharan heat lows, coincide with up to 90% of the seasonal total dust emission over wide areas of North Africa. In contrast to depressions, migrating cyclones that live for more than two days are rare and are associated to 4% of the annual and spatial dust emission average. Migrating cyclones over North Africa occur primarily in spring north of 20° N with eastwards trajectories and typical life times of three to seven days. Regionally larger seasonal totals of dust emission are associated to cyclones with up to 25% over Libya. In summer, near-surface signatures of African Easterly Waves (AEWs) emit regionally up to 15% of the total emission. The diurnal cycle of dust emission underlines that emission associated to cyclones at mid-day is substantially larger than at night by a factor of three to five. Soil moisture weakens dust emission during cyclone passage by 10%. Despite the overall small contribution of migrating cyclones to dust emission, cyclones coincide with particularly intense dust emission events exceeding the climatological mean flux by a factor of four to eight. This implies, that both

  6. Characterizing Mineral Dust from the Arabian Coast of the Red Sea

    NASA Astrophysics Data System (ADS)

    Puthan Purakkal, J.; Stenchikov, G. L.; Engelbrecht, J. P.

    2014-12-01

    The Arabian Peninsula is one of the Earth's major sources of atmospheric dust. Along with profound negative effects on human activity and natural processes in this region, dust is an important nutrient source for the oligothrophic northern Red Sea. From preliminary observations it is estimated that some 18-20 major dust storms per year deposit about 6 Mt of mineral dust into the Red Sea. To better understand the optical properties, health, and ecological impacts of dust, we study the mineralogical, chemical and morphological properties of surface soil samples collected at prevbiously identified potential dust sources along the Arabian coast of the Red Sea. Many of these dust sources lie within a narrow coastal region and because of their proximity to the Red Sea, are important contributors to the dust/nutrient balance, during both dusty and fair weather conditions. Bulk samples were collected from the top 10 mm of soils from three sites along the Arabian coast of the Red Sea. The soil samples were sieved to separate the < 38μm particle fractions for chemical and mineralogical analysis. X-ray diffractometry (XRD) was applied to measure the mineral content of the dust. The chemical composition of individual particles was analyzed using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). From the XRD analysis of the sieved samples from An Masayat (23.3322 N, 38.9481 E), Buthna (23.2960 N, 38.9384 E) and Rabugh pipeline Road (23.292 N, 38.91 E), it was found that the dust was composed largely of hematite, goethite, calcite, dolomite, quartz, chlorite, muscovite, amphibole, epidote and plagioclase. Our results are being compared to, and show similarities to those of Engelbrecht et al. , collected at 15 Middle East sites. Both the mineralogical content and chemical composition of samples bear the signatures of the regional geology. Engelbrecht, J. P., McDonald, E. V., Gillies, J. A., Jayanty, R. K. M., Casuccio, G., and Gertler, A. W., 2009

  7. Assessments for the impact of mineral dust on the meningitis incidence in West Africa

    NASA Astrophysics Data System (ADS)

    Martiny, Nadège; Chiapello, Isabelle

    2013-05-01

    Recently, mineral dust has been suspected to be one of the important environmental risk factor for meningitis epidemics in West Africa. The current study is one of the first which relies on long-term robust aerosol measurements in the Sahel region to investigate the possible impact of mineral dust on meningitis cases (incidence). Sunphotometer measurements, which allow to derive aerosol and humidity parameters, i.e., aerosol optical thickness, Angström coefficient, and precipitable water, are combined with quantitative epidemiological data in Niger and Mali over the 2004-2009 AMMA (African Monsoon Multidisciplinary Analysis) program period. We analyse how the extremely high aerosol loads in this region may influence both the calendar (onset, peaks, end) and the intensity of meningitis. We highlight three distinct periods: (i) from November to December, beginning of the dry season, humidity is weak, there is no dust and no meningitis cases; (ii) from January to April, humidity is still weak, but high dust loads occur in the atmosphere and this is the meningitis season; (iii) from May to October, humidity is high and there is no meningitis anymore, in presence of dust or not, which flow anyway in higher altitudes. More specifically, the onset of the meningitis season is tightly related to mineral dust flowing close to the surface at the very beginning of the year. During the dry, and the most dusty season period, from February to April, each meningitis peak is preceded by a dust peak, with a 0-2 week lead-time. The importance (duration, intensity) of these meningitis peaks seems to be related to that of dust, suggesting that a cumulative effect in dust events may be important for the meningitis incidence. This is not the case for humidity, confirming the special contribution of dust at this period of the year. The end of the meningitis season, in May, coincides with a change in humidity conditions related to the West African Monsoon. These results, which are

  8. Effects of mineral dust on global atmospheric nitrate concentrations

    NASA Astrophysics Data System (ADS)

    Karydis, Vlassis; Tsimpidi, Alexandra; Astitha, Marina; Lelieveld, Jos

    2014-05-01

    Inorganic particulate nitrate contributes significantly to the total aerosol mass. While nitrate is predominantly present in the submicron mode, coarse mode aerosol nitrate can also be produced by adsorption of nitric acid onto soil particles. Naturally emitted particles affect the phase partitioning of nitrate, especially in areas where dust comprises a significant portion of total particulate matter, and the simulation of these effects can considerably improve model predictions. However, most thermodynamic models used in global studies lack a realistic treatment of crustal species. This work aims to improve the representation of nitrate aerosols in the global chemistry climate model EMAC, and addresses the shortcomings of previous models. EMAC calculates the aerosol microphysics and gas/aerosol partitioning by using the GMXe aerosol module. The aerosol size distribution is described by 7 interacting lognormal modes (4 hydrophilic and 3 hydrophobic modes). An advanced dust emission module also accounts for the soil particle size distribution of different deserts worldwide. Gas/aerosol partitioning is simulated using the ISORROPIA-II thermodynamic equilibrium model which considers the interaction of K(+), Ca(+2), Mg(+2), NH4(+), Na(+), SO4(-2), NO3(-), Cl(-), H2O aerosol components. The EMAC model is tested in long-term simulations covering the years 2005-2008. Model predictions are compared with data from the European network EMEP, the IMPROVE network in North America, and the EANET Network in East Asia.

  9. Depletion of tropospheric ozone associated with mineral dust outbreaks.

    PubMed

    Soler, Ruben; Nicolás, J F; Caballero, S; Yubero, E; Crespo, J

    2016-10-01

    From May to September 2012, ozone reductions associated with 15 Saharan dust outbreaks which occurred between May to September 2012 have been evaluated. The campaign was performed at a mountain station located near the eastern coast of the Iberian Peninsula. The study has two main goals: firstly, to analyze the decreasing gradient of ozone concentration during the course of the Saharan episodes. These gradients vary from 0.2 to 0.6 ppb h(-1) with an average value of 0.39 ppb h(-1). The negative correlation between ozone and coarse particles occurs almost simultaneously. Moreover, although the concentration of coarse particles remained high throughout the episode, the time series shows the saturation of the ozone loss. The highest ozone depletion has been obtained during the last hours of the day, from 18:00 to 23:00 UTC. Outbreaks registered during this campaign have been more intense in this time slot. The second objective is to establish from which coarse particle concentration a significant ozone depletion can be observed and to quantify this reduction. In this regard, it has been confirmed that when the hourly particle concentration recorded during the Saharan dust outbreaks is above the hourly particle median values (N > N-median), the ozone concentration reduction obtained is statistically significant. An average ozone reduction of 5.5 % during Saharan events has been recorded. In certain cases, this percentage can reach values of higher than 15 %. PMID:27376369

  10. The immersion freezing behavior of mineral dust particles mixed with biological substances

    NASA Astrophysics Data System (ADS)

    Augustin-Bauditz, S.; Wex, H.; Denjean, C.; Hartmann, S.; Schneider, J.; Schmidt, S.; Ebert, M.; Stratmann, F.

    2015-10-01

    Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INM). It has been suggested that these INM maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INM in e.g., soils, resulting in an internal mixture of mineral dust and INM. If particles from such soils which contain biological INM are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above -20 up to almost 0 °C. To explore this hypothesis, we performed a measurement campaign within the research unit INUIT, where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). To characterize the mixing state of the generated aerosol we used different methods which will also be discussed. We found that internally mixed particles, containing ice active biological material, follow the ice nucleation behavior observed for the purely biological particles, i.e. freezing occurs at temperatures at which mineral dusts themselves are not yet ice active. It can be concluded that INM located on a mineral dust particle determine the freezing behavior of that particle.

  11. 76 FR 30878 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-27

    ... FR 64412), extended January 14, 2011 (76 FR 2617) and May 4, 2011 (76 FR 25277), is further extended. All comments must be received or postmarked by midnight Eastern Daylight Saving Time on June 20, 2011... Continuous Personal Dust Monitors. This extension gives commenters additional time to review and comment...

  12. Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica

    DOE PAGES

    Sudarchikova, Natalia; Mikolajewicz, Uwe; Timmreck, C.; O'Donnell, D.; Schurgers, G.; Sein, Dmitry; Zhang, Kai

    2015-05-19

    The mineral dust cycle responds to climate variations and plays an important role in the climate system by affecting the radiative balance of the atmosphere and modifying biogeochemistry. Polar ice cores provide unique information about deposition of aeolian dust particles transported over long distances. These cores are a palaeoclimate proxy archive of climate variability thousands of years ago. The current study is a first attempt to simulate past interglacial dust cycles with a global aerosol–climate model ECHAM5-HAM. The results are used to explain the dust deposition changes in Antarctica in terms of quantitative contribution of different processes, such as emission,more » atmospheric transport and precipitation, which will help to interpret palaeodata from Antarctic ice cores. The investigated periods include four interglacial time slices: the pre-industrial control (CTRL), mid-Holocene (6000 yr BP; hereafter referred to as \\"6 kyr\\"), last glacial inception (115 000 yr BP; hereafter \\"115 kyr\\") and Eemian (126 000 yr BP; hereafter \\"126 kyr\\"). One glacial time interval, the Last Glacial Maximum (LGM) (21 000 yr BP; hereafter \\"21 kyr\\"), was simulated as well to be a reference test for the model. Results suggest an increase in mineral dust deposition globally, and in Antarctica, in the past interglacial periods relative to the pre-industrial CTRL simulation. Approximately two-thirds of the increase in the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust emissions. Slightly strengthened transport efficiency causes the remaining one-third of the increase in dust deposition. The moderate change in dust deposition in Antarctica in the last glacial inception period is caused by the slightly stronger poleward atmospheric transport efficiency compared to the pre-industrial. Maximum dust deposition in Antarctica was simulated for the glacial period. LGM dust deposition in Antarctica is substantially increased due to 2.6 times

  13. Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica

    SciTech Connect

    Sudarchikova, Natalia; Mikolajewicz, Uwe; Timmreck, C.; O'Donnell, D.; Schurgers, G.; Sein, Dmitry; Zhang, Kai

    2015-05-19

    The mineral dust cycle responds to climate variations and plays an important role in the climate system by affecting the radiative balance of the atmosphere and modifying biogeochemistry. Polar ice cores provide unique information about deposition of aeolian dust particles transported over long distances. These cores are a palaeoclimate proxy archive of climate variability thousands of years ago. The current study is a first attempt to simulate past interglacial dust cycles with a global aerosol–climate model ECHAM5-HAM. The results are used to explain the dust deposition changes in Antarctica in terms of quantitative contribution of different processes, such as emission, atmospheric transport and precipitation, which will help to interpret palaeodata from Antarctic ice cores. The investigated periods include four interglacial time slices: the pre-industrial control (CTRL), mid-Holocene (6000 yr BP; hereafter referred to as \\"6 kyr\\"), last glacial inception (115 000 yr BP; hereafter \\"115 kyr\\") and Eemian (126 000 yr BP; hereafter \\"126 kyr\\"). One glacial time interval, the Last Glacial Maximum (LGM) (21 000 yr BP; hereafter \\"21 kyr\\"), was simulated as well to be a reference test for the model. Results suggest an increase in mineral dust deposition globally, and in Antarctica, in the past interglacial periods relative to the pre-industrial CTRL simulation. Approximately two-thirds of the increase in the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust emissions. Slightly strengthened transport efficiency causes the remaining one-third of the increase in dust deposition. The moderate change in dust deposition in Antarctica in the last glacial inception period is caused by the slightly stronger poleward atmospheric transport efficiency compared to the pre-industrial. Maximum dust deposition in Antarctica was simulated for the glacial period. LGM dust deposition in Antarctica is substantially increased due to 2.6 times higher

  14. An online mineral dust model within the global/regional NMMB: current progress and plans

    NASA Astrophysics Data System (ADS)

    Perez, C.; Haustein, K.; Janjic, Z.; Jorba, O.; Baldasano, J. M.; Black, T.; Nickovic, S.

    2008-12-01

    While mineral dust distribution and effects are important on global scales, they strongly depend on dust emissions that are occurring on small spatial and temporal scales. Indeed, the accuracy of surface wind speed used in dust models is crucial. Due to the high-order power dependency on wind friction velocity and the threshold behaviour of dust emissions, small errors in surface wind speed lead to large dust emission errors. Most global dust models use prescribed wind fields provided by major meteorological centres (e.g., NCEP and ECMWF) and their spatial resolution is currently about 1 degree x 1 degree . Such wind speeds tend to be strongly underestimated over arid and semi-arid areas and do not account for mesoscale systems responsible for a significant fraction of dust emissions regionally and globally. Other significant uncertainties in dust emissions resulting from such approaches are related to the misrepresentation of high subgrid-scale spatial heterogeneity in soil and vegetation boundary conditions, mainly in semi-arid areas. In order to significantly reduce these uncertainties, the Barcelona Supercomputing Center is currently implementing a mineral dust model coupled on-line with the new global/regional NMMB atmospheric model using the ESMF framework under development in NOAA/NCEP/EMC. The NMMB is an evolution of the operational WRF-NMME extending from meso to global scales, and including non-hydrostatic option and improved tracer advection. This model is planned to become the next-generation NCEP mesoscale model for operational weather forecasting in North America. Current implementation is based on the well established regional dust model and forecast system Eta/DREAM (http://www.bsc.es/projects/earthscience/DREAM/). First successful global simulations show the potentials of such an approach and compare well with DREAM regionally. Ongoing developments include improvements in dust size distribution representation, sedimentation, dry deposition, wet

  15. Observations of smoke and mineral dust over Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Nisantzi, Argyro; Elisavet Mamouri, Rodanthi; Hadjimitsis, Diofandos; Ansmann, Albert

    2016-04-01

    Four-year combined observations (2010-2014) with EARLINET polarization lidar and AERONET sun/sky photometer at Limassol (34.7 N, 33 E), Cyprus, Eastern Mediterranean, were used in order to study the soil dust content in lofted fire smoke plumes. This study focuses on air masses advected from Turkey as well regions further north of Black Sea during the main burning season (summer half year). Cases with strong impact of smoke events (occurring over Turkey during 1-3 days before arrival at Limassol) and observations with more background-like aerosol signatures (not influenced by Turkish fire smoke) were separated. This first systematic attempt to characterize less than 3-day-old smoke plumes in terms of particle linear depolarization ratio (PDR), measured with lidar, shown that PDR was typically 10-15% when Turkish fires contributed to the aerosol burden in the free troposphere and considerably lower with values 3-8% when fires over Turkey were absent while the air masses cross this country. High Ångström exponents of 1.4-2.2 during all these events with lofted smoke layers, occurring between 1 and 3 km height, suggest the absence of a pronounced particle coarse mode. When PDR plotted vs. travel time (spatial distance between Limassol and last fire area), PDR decreased strongly from initial values around 16-18% (1 day travel) to 4-8% after 4 days of travel caused by deposition processes. This behavior was found to be in close agreement with findings described in the literature. Biomass burning should therefore be considered as another source of free tropospheric soil dust.

  16. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-10-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  17. Predicting the Mineral Composition of Dust Aerosols. Part 1; Representing Key Processes

    NASA Technical Reports Server (NTRS)

    Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

    2015-01-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wetsieved soil and the emitted aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent at these diameters in a soil whose aggregates are dispersed by wet sieving. We calculate the emitted mass of each mineral with respect to size by accounting for the disintegration of soil aggregates during wet sieving. These aggregates are emitted during mobilization and fragmentation of the original undispersed soil that is subject to wind erosion. The emitted aggregates are carried far downwind from their parent soil. The soil mineral fractions used to calculate the aggregates also include larger particles that are suspended only in the vicinity of the source. We calculate the emitted size distribution of these particles using a normalized distribution derived from aerosol measurements. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to

  18. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron availability

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-06-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. The nano-thin platelets included illite, smectite, illite-smectite mixed layers and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on microgrids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than in Asian dust, while Asian dust was more enriched in chlorite. The average Fe / Si, Al / Si and Fe / Al molar ratios of the clay minerals, compared to previously reported chemistries of mineral dusts and leached solutions, indicated that dissolved Fe originated from clay minerals. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite are important sources of available Fe in

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    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 <20% in the North Atlantic Ocean to >50% in the South Pacific Ocean; this explains the variability in the fraction of bioavailable P commonly observed in important oceanic regions.

  1. Chemical processing does not always impair heterogeneous ice nucleation of mineral dust particles

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Demott, P. J.; Prenni, A. J.; Minambres, L.; Kreidenweis, S. M.; Moehler, O.

    2010-12-01

    Mineral dust particles are the most abundant heterogeneous ice nuclei in the atmosphere. They also frequently become mixed with secondary material during atmospheric transport. The effect that such atmospheric processing has on the ice nucleation properties of dust particles remains under investigation. We have studied changes in the ice nucleation ability of various mineral dust sources after exposure to nitric acid in an aerosol flow tube, and after heterogeneous nucleation of α-pinene secondary organic aerosol (SOA) in the AIDA cloud expansion chamber. Both chemical treatments altered and homogenized the dust particles’ heterogeneous ice nucleation properties below water-saturation, but had no apparent impact on the immersion-freezing fraction well above water saturation. The fraction of particles capable of nucleating ice at fixed mixed-phase cloud temperatures between -35 and -15 °C was determined using a continuous flow diffusion chamber (CFDC) as the relative humidity with respect to water (RHw) was scanned from 75% to 110% RHw. Exposure to both nitric acid and SOA impaired essentially all ice nucleation in the deposition-regime below water saturation, while causing the onset of condensation-freezing to occur in a step-wise manner over a small range of RHw just below water saturation. We interpret this as the result of an increase in particle hygroscopicity following chemical treatment. This allows the mineral particles to absorb enough water to overcome solute freezing point depression effects and nucleate ice via condensation-freezing at a slightly smaller and narrower range of RHw than the less hygroscopic untreated dust can. Immersion-freezing above water saturation was not affected by either treatment. This is in stark contrast to earlier experiments where dust was exposed to sulfuric acid from a heated vapor source; ice nucleation was notably impaired in both the deposition and immersion-freezing regimes following sulfuric acid treatment.

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

    NASA Astrophysics Data System (ADS)

    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 <20% in the North Atlantic Ocean to >50% in the South Pacific Ocean; this explains the variability in the fraction of bioavailable P commonly observed in important oceanic regions.

  3. Long-range transport across the Atlantic in summertime does not enhance the hygroscopicity of African mineral dust

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Caquineau, S.; Desboeufs, K.; Laurent, B.; Maille, M.; Quiñones Rosado, M.; Vallejo, P.; Mayol-Bracero, O. L.; Formenti, P.

    2015-09-01

    We present the first direct evidence that the hygroscopic properties of super micron (>1 µm) African dust particles did not change despite undergoing long-range transport across the Atlantic toward the Caribbean. Concurrent measurements of chemical composition show that most of mineral dust was chemically unprocessed and externally mixed. A minor portion of mineral dust was internally mixed with sulfate and chloride (~13-24% by number) or aggregated with sea-salt particles (~3-6%). Only dust particles aggregated with sea salt showed significant hygroscopic growth above 75% relative humidity (RH), resulting in a decrease in extinction mass efficiency by up to a factor 2.2. All other dust particles did not take up significant amounts of water when exposed to up to 94% RH. These results demonstrate that the direct radiative effect of African dust in this region remained independent of RH and an external mixing state could be considered for evaluating the climate effects of dust.

  4. Role of clay minerals in the formation of atmospheric aggregates of Saharan dust

    NASA Astrophysics Data System (ADS)

    Cuadros, Javier; Diaz-Hernandez, José L.; Sanchez-Navas, Antonio; Garcia-Casco, Antonio

    2015-11-01

    Saharan dust can travel long distances in different directions across the Atlantic and Europe, sometimes in episodes of high dust concentration. In recent years it has been discovered that Saharan dust aerosols can aggregate into large, approximately spherical particles of up to 100 μm generated within raindrops that then evaporate, so that the aggregate deposition takes place most times in dry conditions. These aerosol aggregates are an interesting phenomenon resulting from the interaction of mineral aerosols and atmospheric conditions. They have been termed "iberulites" due to their discovery and description from aerosol deposits in the Iberian Peninsula. Here, these aggregates are further investigated, in particular the role of the clay minerals in the aggregation process of aerosol particles. Iberulites, and common aerosol particles for reference, were studied from the following periods or single dust events and locations: June 1998 in Tenerife, Canary Islands; June 2001 to August 2002, Granada, Spain; 13-20 August 2012, Granada; and 1-6 June 2014, Granada. Their mineralogy, chemistry and texture were analysed using X-ray diffraction, electron microprobe analysis, SEM and TEM. The mineral composition and structure of the iberulites consists of quartz, carbonate and feldspar grains surrounded by a matrix of clay minerals (illite, smectite and kaolinite) that also surrounds the entire aggregate. Minor phases, also distributed homogenously within the iberulites, are sulfates and Fe oxides. Clays are apparently more abundant in the iberulites than in the total aerosol deposit, suggesting that iberulite formation concentrates clays. Details of the structure and composition of iberulites differ from descriptions of previous samples, which indicates dependence on dust sources and atmospheric conditions, possibly including anthropic activity. Iberulites are formed by coalescence of aerosol mineral particles captured by precursor water droplets. The concentration of

  5. Mineral phases of weathered and recent electric arc furnace dust.

    PubMed

    Martins, Fernanda Machado; dos Reis Neto, José Manoel; da Cunha, Carlos Jorge

    2008-06-15

    A weathered and a recent sample of electric arc furnace dust (EAFD), generated in a southern Brazilian steel industry, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) probe and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. One sample, in the form of a wet paste, was collected from the lowest part of a landfill and corresponds to a weathered material whereas the other sample was collected from the top portion of the landfill and corresponds to a recently produced material. The dominant cations present in both samples are iron, zinc and lead with minor amounts of manganese, calcium and silicon. The dominant mineralogical phases identified in both materials are Magnetite, Franklinite and Zincite. The recent sample has Laurionite whereas the weathered sample has Hydrocerussite and Hydrozincite.

  6. Predicting the mineral composition of dust aerosols - Part 1: Representing key processes

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-02-01

    Soil dust aerosols created by wind erosion are typically assigned globally uniform physical and chemical properties within Earth system models, despite known regional variations in the mineral content of the parent soil. Mineral composition of the aerosol particles is important to their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, coating by heterogeneous uptake of sulfates and nitrates, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Here, aerosol mineral composition is derived by extending a method that provides the composition of a wet-sieved soil. The extension accounts for measurements showing significant differences between the mineral fractions of the wet-sieved soil and the resulting aerosol concentration. For example, some phyllosilicate aerosols are more prevalent at silt sizes, even though they are nearly absent in a soil whose aggregates are dispersed by wet sieving during analysis. We reconstruct the undispersed size distribution of the original soil that is subject to wind erosion. An empirical constraint upon the relative emission of clay and silt is applied that further differentiates the soil and aerosol mineral composition. In addition, a method is proposed for mixing minerals with small impurities composed of iron oxides. These mixtures are important for transporting iron far from the dust source, because pure iron oxides are more dense and vulnerable to gravitational removal than most minerals comprising dust aerosols. A limited comparison to measurements from North Africa shows that the extension brings the model into better agreement, consistent with a more extensive comparison to global observations as well as measurements of elemental composition downwind of the Sahara, as described in companion articles.

  7. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    DOE PAGES

    Zhang, Y.; Mahowald, N.; Scanza, R. A.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J. F.; Zhuang, G.; Chen, Y.; Cohen, D. D.; et al

    2015-10-12

    Trace element deposition from desert dust has important impacts on ocean primary productivity, the quantification of which could be useful in determining the magnitude and sign of the biogeochemical feedback on radiative forcing. However, the impact of elemental deposition to remote ocean regions is not well understood and is not currently included in global climate models. In this study, emission inventories for eight elements primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si are determined based on a global mineral data set and a soil data set. The resulting elemental fractions are used to drive themore » 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 is evident on a global scale, particularly for Ca. Simulations of global variations in the Ca / Al ratio, which typically range from around 0.1 to 5.0 in soils, are consistent with observations, suggesting that this ratio is a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different; estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observations of elemental aerosol concentrations 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 range from 0.7 to 1.6, except for Mg and Mn (3.4 and 3.5, respectively). Using the soil database improves the correspondence of the spatial heterogeneity in the modeling of several elements (Ca, Al and Fe) compared to observations. Total and soluble dust element fluxes to different ocean basins and ice sheet regions have been estimated, based on the model results. The annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using the mineral data set are

  8. Modeling the global emission, transport and deposition of trace elements associated with mineral dust

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Mahowald, N.; Scanza, R. A.; Journet, E.; Desboeufs, K.; Albani, S.; Kok, J. F.; Zhuang, G.; Chen, Y.; Cohen, D. D.; Paytan, A.; Patey, M. D.; Achterberg, E. P.; Engelbrecht, J. P.; Fomba, K. W.

    2015-10-01

    Trace element deposition from desert dust has important impacts on ocean primary productivity, the quantification of which could be useful in determining the magnitude and sign of the biogeochemical feedback on radiative forcing. However, the impact of elemental deposition to remote ocean regions is not well understood and is not currently included in global climate models. In this study, emission inventories for eight elements primarily of soil origin, Mg, P, Ca, Mn, Fe, K, Al, and Si are determined based on a global mineral data set and a soil data set. The resulting elemental fractions are 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 is evident on a global scale, particularly for Ca. Simulations of global variations in the Ca / Al ratio, which typically range from around 0.1 to 5.0 in soils, are consistent with observations, suggesting that this ratio is a good signature for dust source regions. The simulated variable fractions of chemical elements are sufficiently different; estimates of deposition should include elemental variations, especially for Ca, Al and Fe. The model results have been evaluated with observations of elemental aerosol concentrations 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 range from 0.7 to 1.6, except for Mg and Mn (3.4 and 3.5, respectively). Using the soil database improves the correspondence of the spatial heterogeneity in the modeling of several elements (Ca, Al and Fe) compared to observations. Total and soluble dust element fluxes to different ocean basins and ice sheet regions have been estimated, based on the model results. The annual inputs of soluble Mg, P, Ca, Mn, Fe and K associated with dust using the mineral data set are 0.30 Tg

  9. Mineral dust archive in Taylor Dome ice core as evidence for shifting coastal east Antarctic climate during the LGM-Holocene transition

    NASA Astrophysics Data System (ADS)

    Aarons, S. M.; Aciego, S.; Gabrielli, P.; Delmonte, B.; Koornneef, J.; Bouman, C.; Wegner, A.

    2014-12-01

    Ice cores from ice sheets in Antarctica provide valuable records of past climates encompassing hundreds of thousands of years. Chemical and mineralogical characterization of aerosol mineral particles (dust) transported through the atmosphere and deposited on ice sheets and glaciers provide insight into the regional and global climate conditions during a time period. Elemental and isotopic analysis of dust entrapped in ice aids in determining provenance, with variations signifying changes in dust production, sources and transport pathways, indicating an evolving local and/or global climate. We present radiogenic isotope and elemental compositions of insoluble dust entrained in a coastal Antarctic ice core during the transition from the Last Glacial Maximum (LGM) to the Holocene. A series of 15 samples from the Taylor Dome ice core, 113-391 m in depth covering a time period of 1.8-31.5 ka were analyzed using traditional Thermal Ionization Mass Spectrometry (TIMS) equipped with 10-11 Ohm resistors (87Sr/86Sr) and 10-13 Ohm resistors (143Nd/144Nd). We determined trace (TE) and rare earth element (REE) concentrations by Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SFMS) and dust concentration and size distribution by Coulter Counter. The radiogenic isotopic compositions of glacial dust agrees with previously measured Antarctic dust: 87Sr/86Sr= 0.7052 - 0.7124 and ɛNd= -0.9 - -4.7, whereas Holocene dust displays a broader range from 87Sr/86Sr= 0.7054 - 0.7163 and ɛNd= -0.9 - -7.1, suggesting a shift from globally transported dust to more variable local input following the LGM to Holocene transition. The REE and TE concentrations display typical East Antarctic ice core dust patterns. The average dust particle diameter increases from ~1.8 to ~3 μm with decreasing depositional age, supporting the alteration in dust transport mechanism hypothesis. Our results display dust concentrations of >500 and <15 ppb during glacial and interglacial periods

  10. Magnetic Properties of Iron Oxide Minerals in Atmospheric Dust and Source Sediments from Western US

    NASA Astrophysics Data System (ADS)

    Moskowitz, B. M.; Yauk, K.; Till, J. L.; Berquo, T. S.; Banerjee, S. K.; Reynolds, R. L.; Goldstein, H. L.

    2011-12-01

    Atmospheric dust contains iron oxide minerals that can play important roles in various physical and biological processes affecting atmospheric and surface temperatures, marine phytoplankton productivity, and human health. Iron oxide minerals in dust deposited on mountain snow cover are especially important because these minerals absorb solar and IR radiation leading to changes in albedo and affecting the timing and rate of spring and summer snowpack melting. As part of an ongoing project to study physical and chemical properties of dust from sources to sinks in the western US, we will describe one approach to characterize iron oxide mineralogy using magnetic property measurements and Mossbauer spectroscopy. Magnetic property measurements over a wide range of temperatures (2-300 K) and magnetic fields (0-5 T) are particularly sensitive to composition, particle size (from nanometer to micrometer), and concentration of iron oxide and oxyhydroxide minerals. The high sensitivity of magnetic measurements to target minerals allows the measurement of bulk samples preventing any aliasing of composition or grain size resulting from attempts at prior magnetic separation. In addition, different magnetic measurement protocols can isolate different particle-size assemblages and different compositions in multicomponent mixtures and help to identify dust-source areas. These techniques have been applied to dust deposited on snow (DOS) cover of the San Juan Mountains, Colorado (collected 2005-2010) and Wasatch Mountains, Utah (collected 2010) and possible dust-source sediments from the North American Great Basin and Colorado Plateau deserts. Results show that all samples contain a high coercivity phase consistent with hematite and/or goethite as the dominate ferric oxide mineral plus minor amounts of magnetite (<0.5 wt%). The presence of magnetite was determined from the detection of the characteristic Verwey transition (T=121 K) on low-temperature (< 300 K) remanence and

  11. Chemistry and mineralogy of clay minerals in Asian and Saharan dusts and the implications for iron supply to the oceans

    NASA Astrophysics Data System (ADS)

    Jeong, G. Y.; Achterberg, E. P.

    2014-11-01

    Mineral dust supplied to remote ocean regions stimulates phytoplankton growth through delivery of micronutrients, notably iron (Fe). Although attention is usually paid to Fe (hydr)oxides as major sources of available Fe, Fe-bearing clay minerals are typically the dominant phase in mineral dust. The mineralogy and chemistry of clay minerals in dust particles, however, are largely unknown. We conducted microscopic identification and chemical analysis of the clay minerals in Asian and Saharan dust particles. Cross-sectional slices of dust particles were prepared by focused ion beam (FIB) techniques and analyzed by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS). TEM images of FIB slices revealed that clay minerals occurred as either nano-thin platelets or relatively thick plates. Chemical compositions and lattice fringes of the nano-thin platelets suggested that they included illite, smectite, illite-smectite mixed layers, and their nanoscale mixtures (illite-smectite series clay minerals, ISCMs) which could not be resolved with an electron microbeam. EDXS chemical analysis of the clay mineral grains revealed that the average Fe content was 5.8% in nano-thin ISCM platelets assuming 14% H2O, while the Fe content of illite and chlorite was 2.8 and 14.8%, respectively. In addition, TEM and EDXS analyses were performed on clay mineral grains dispersed and loaded on micro-grids. The average Fe content of clay mineral grains was 6.7 and 5.4% in Asian and Saharan dusts, respectively. A comparative X-ray diffraction analysis of bulk dusts showed that Saharan dust was more enriched in clay minerals than Asian dust, while Asian dust was more enriched in chlorite. Clay minerals, in particular nanocrystalline ISCMs and Fe-rich chlorite, are probably important sources of Fe to remote marine ecosystems. Further detailed analyses of the mineralogy and chemistry of clay minerals in global mineral dusts are required to evaluate the

  12. Variability of mineral dust deposition in the western Mediterranean basin and south-east of France

    NASA Astrophysics Data System (ADS)

    Vincent, Julie; Laurent, Benoit; Losno, Rémi; Bon Nguyen, Elisabeth; Roullet, Pierre; Sauvage, Stéphane; Chevaillier, Servanne; Coddeville, Patrice; Ouboulmane, Noura; di Sarra, Alcide Giorgio; Tovar-Sánchez, Antonio; Sferlazzo, Damiano; Massanet, Ana; Triquet, Sylvain; Morales Baquero, Rafael; Fornier, Michel; Coursier, Cyril; Desboeufs, Karine; Dulac, François; Bergametti, Gilles

    2016-07-01

    provenance, transport and deposition processes (i.e. wet vs. dry) of dust are different and specific for the different deposition sites in the Mediterranean studied area. The results tend to indicate that wet deposition is the main form of deposition for mineral dust in the western Mediterranean basin, but the contribution of dry deposition (in the sense that no precipitation was detected at the surface) is far from being negligible, and contributes 10 to 46 % to the major dust deposition events, depending on the sampling site.

  13. How important are atmospheric depressions and mobile cyclones for emitting mineral dust aerosol in North Africa?

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Schepanski, K.; Knippertz, P.; Heinold, B.; Tegen, I.

    2014-09-01

    This study presents the first quantitative estimate of the mineral dust emission associated with atmospheric depressions and mobile cyclones in North Africa. Atmospheric depressions are automatically tracked at 925 hPa based on ERA-Interim data from the European Centre for Medium-Range Weather Forecasts for 1989-2008. A set of filter criteria is applied to identify mobile cyclones, i.e. migrating and long-lived cyclones. The shorter term cyclone is used as a synonym for mobile cyclones. Dust emission is calculated with a dust emission model driven by 10 m winds and soil moisture from ERA-Interim. Emission peaks during winter and spring with spatial averages of 250-380 g m-2 per month. Comparison of the dust source activation frequency from the model against SEVIRI satellite observation shows a good agreement in the Bodélé Depression but differences in the north and west of North Africa. Depressions are abundant, particularly in summer when the Saharan heat low is situated over West Africa and during spring in the lee of the Atlas Mountains. Up to 90% (55% annually and spatially averaged) of dust emission occurs within 10 degrees of these depressions, with embedded mechanisms such as nocturnal low-level jets playing a role. Cyclones are rarer and occur primarily north of 20° N in spring in agreement with previous studies and over summertime West Africa consistent with near-surface signatures of African Easterly Waves. Dust emission within 10 degrees of cyclones peaks over Libya with up to 25% in spring. Despite the overall small contribution of 4% annually and spatially averaged, cyclones coincide with particularly intense dust emission events exceeding the climatological mean by a factor of four to eight. Soil moisture weakens dust emission during cyclone passage by about 10%.

  14. Long-range transport of mineral dust in the global atmosphere: Impact of African dust on the environment of the southeastern United States

    PubMed Central

    Prospero, Joseph M.

    1999-01-01

    Soil dust is a major constituent of airborne particles in the global atmosphere. Dust plumes frequently cover huge areas of the earth; they are one of the most prominent and commonly visible features in satellite imagery. Dust is believed to play a role in many biogeochemical processes, but the importance of dust in these processes is not well understood because of the dearth of information about the global distribution of dust and its physical, chemical, and mineralogical properties. This paper describes some features of the large-scale distribution of dust and identifies some of the geological characteristics of important source areas. The transport of dust from North Africa is presented as an example of possible long-range dust effects, and the impact of African dust on environmental processes in the western North Atlantic and the southeastern United States is assessed. Dust transported over long distances usually has a mass median diameter <10 μm. Small wind-borne soil particles show signs of extensive weathering; consequently, the physical and chemical properties of the particles will greatly depend on the weathering history in the source region and on the subsequent modifications that occur during transit in the atmosphere (typically a period of a week or more). To fully understand the role of dust in the environment and in human health, mineralogists will have to work closely with scientists in other disciplines to characterize the properties of mineral particles as an ensemble and as individual particles especially with regard to surface characteristics. PMID:10097049

  15. Long-Range Transport of Mineral Dust in the Global Atmosphere: Impact of African Dust on the Environment of the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Prospero, Joseph M.

    1999-03-01

    Soil dust is a major constituent of airborne particles in the global atmosphere. Dust plumes frequently cover huge areas of the earth; they are one of the most prominent and commonly visible features in satellite imagery. Dust is believed to play a role in many biogeochemical processes, but the importance of dust in these processes is not well understood because of the dearth of information about the global distribution of dust and its physical, chemical, and mineralogical properties. This paper describes some features of the large-scale distribution of dust and identifies some of the geological characteristics of important source areas. The transport of dust from North Africa is presented as an example of possible long-range dust effects, and the impact of African dust on environmental processes in the western North Atlantic and the southeastern United States is assessed. Dust transported over long distances usually has a mass median diameter <10 μ m Small wind-borne soil particles show signs of extensive weathering; consequently, the physical and chemical properties of the particles will greatly depend on the weathering history in the source region and on the subsequent modifications that occur during transit in the atmosphere (typically a period of a week or more). To fully understand the role of dust in the environment and in human health, mineralogists will have to work closely with scientists in other disciplines to characterize the properties of mineral particles as an ensemble and as individual particles especially with regard to surface characteristics.

  16. Enrichment of Mineral Dust Storm Particles with Sea Salt Elements - Using bulk and Single Particle Analyses

    NASA Astrophysics Data System (ADS)

    Mamane, Y.; Perrino, C.; Yossef, O.

    2009-12-01

    Mineral aerosol emitted from African and Asian deserts plays an important role in the atmosphere. During their long-range transport, the physical and chemical properties of mineral dust particles change due to heterogeneous reactions with trace gases, coagulation with other particles, and in-cloud processing. These processes affect the optical and hygroscopic properties of dust particles, and in general influencing the physics and chemistry of the atmosphere. Four African and Arabian dust storm episodes affecting the East Mediterranean Coast in the spring of 2006 have been characterized, to determine if atmospheric natural dust particles are enriched with sea salt and anthropogenic pollution. Particle samplers included PM10 and manual dichotomous sampler that collected fine and coarse particles. Three sets of filters were used: Teflon filters for gravimetric, elemental and ionic analyses; Pre-fired Quartz-fiber filters for elemental and organic carbon; and Nuclepore filters for scanning electron microscopy analysis. Computer-controlled scanning electron microscopy (Philips XL 30 ESEM) was used to analyze single particle, for morphology, size and chemistry of selected filter samples. A detailed chemical and microscopical characterization has been performed for the particles collected during dust event days and during clear days. The Saharan and Arabian air masses increased significantly the daily mass concentrations of the coarse and the fine particle fractions. Carbonates, mostly as soil calcites mixed with dolomites, and silicates are the major components of the coarse fraction, followed by sea salt particles. In addition, the levels of anthropogenic heavy metals and sea salt elements registered during the dust episode were considerably higher than levels recorded during clear days. Sea salt elements contain Na and Cl, and smaller amounts of Mg, K, S and Br. Cl ranges from 300 to 5500 ng/m3 and Na from 100 to almost 2400 ng/m3. The Cl to Na ratio on dusty days in

  17. Medical Geology in the Middle East: Potential Health Risks from Mineralized Dust Exposure

    NASA Astrophysics Data System (ADS)

    Lyles, M. B.; Fredrickson, H. L.; Bednar, A. J.; Fannin, H. B.; Griffin, D. W.; Sobecki, T. M.

    2012-04-01

    In the Middle East, dust and sand storms are a persistent problem delivering significant amounts of mineralized particulates via inhalation into the mouth, nasal pharynx, and lungs. The health risks of this dust inhalation are presently being studied but accurate characterization as to the potential health effects is still lacking. Experiments were designed to study the chemical composition, mineral content, and microbial flora of Kuwaiti and Iraqi dust particles for the potential to cause adverse human health effects both acute and chronic. Multiple site samples were collected and chemical and physical characterization including particle size distribution and inorganic analysis was conducted, followed by analysis and identification of biologic flora to include bacteria, fungi and viruses. Additionally, PM10 exposure data was collected hourly over a 12 day period (>10,000 ug/m3). Data indicates that the mineralized dust is composed of calcium carbonate and magnesium sulfate coating over a precipitated matrix of metallic silicate nanocrystals of various forms containing a variety of trace and heavy metals constituting ~3 % of the particles by weight. This includes ~ 1% by weight bioaccessible aluminum and reactive iron with the remaining 1% a mixture of bioaccessible trace and heavy metals. Microbial analysis reveals a significant biodiversity of bacteria of which ~25 % are known pathogens. Of the microbes identified, several have hemolytic properties and most have significant antibiotic resistance. Viral analysis indicates a tremendous amount of virons with a large percent of RNA viruses. The level of total suspended particle mass at PM10 constitutes an excessive exposure micro-particulates including PM 2.5 (~1,0000 ug/m3). Reported data on cell culture and animal studies have indicated a high level of toxicity to these dust particles. Taken together, these data suggest that at the level of dust exposure commonly found in the Middle East (i.e., Iraq, Kuwait, and

  18. Technical note: Mineralogical, chemical, morphological, and optical interrelationships of mineral dust re-suspensions

    NASA Astrophysics Data System (ADS)

    Engelbrecht, Johann P.; Moosmüller, Hans; Pincock, Samuel; Jayanty, R. K. M.; Lersch, Traci; Casuccio, Gary

    2016-08-01

    This paper promotes an understanding of the mineralogical, chemical, and physical interrelationships of re-suspended mineral dusts collected as grab samples from global dust sources. Surface soils were collected from arid regions, including the southwestern USA, Mali, Chad, Morocco, Canary Islands, Cabo Verde, Djibouti, Afghanistan, Iraq, Kuwait, Qatar, UAE, Serbia, China, Namibia, Botswana, Australia, and Chile. The < 38 µm sieved fraction of each sample was re-suspended in a chamber, from which the airborne mineral dust could be extracted, sampled, and analyzed. Instruments integrated into the entrainment facility included two PM10 and two PM2.5 filter samplers, a beta attenuation gauge for the continuous measurement of PM10 and PM2.5 particulate mass fractions, an aerodynamic particle size analyzer, and a three-wavelength (405, 532, 781 nm) photoacoustic instrument with integrating reciprocal nephelometer for monitoring absorption and scattering coefficients during the dust re-suspension process. Filter sampling media included Teflon® membrane and quartz fiber filters for chemical analysis and Nuclepore® filters for individual particle analysis by scanning electron microscopy (SEM). The < 38 µm sieved fractions were also analyzed by X-ray diffraction for their mineral content while the > 75, < 125 µm soil fractions were mineralogically assessed by optical microscopy. Presented here are results of the optical measurements, showing the interdependency of single-scattering albedos (SSA) at three different wavelengths and mineralogical content of the entrained dust samples. To explain the elevated concentrations of iron (Fe) and Fe / Al ratios in the soil re-suspensions, we propose that dust particles are to a large extent composed of nano-sized particles of micas, clays, metal oxides, and ions of potassium (K+), calcium (Ca2+), and sodium

  19. Characterization and Acid-Mobilization Study of Iron-Containing Mineral Dust Source Materials

    SciTech Connect

    Cwiertny, David M.; Baltrusaitis, Jonas; Hunter, Gordon J.; Laskin, Alexander; Scherer, Michelle; Grassian, Vicki H.

    2008-03-04

    Processes that solubilize the iron in mineral dust aerosols may increase the amount of iron supplied to ocean surface waters, and thereby stimulate phytoplankton productivity. It was recently proposed that mixing of mineral dusts with SO2 and HNO3 produces extremely acidic environments that favor the formation of bioavailable Fe(II). Here, four authentic mineral dust source materials (Saudi Beach sand (SB), Inland Saudi sand (IS), Saharan Sand (SS) and China Loess (CL)) and one commercial reference material (Arizona Test Dust (AZTD)) were spectroscopically characterized, and their dissolution at pH 1 was examined in aqueous batch systems. Spectroscopic analyses indicated that the bulk and near-surface region of all samples possessed similar elemental compositions and that iron was unevenly distributed among dust 10 particles. Mössbauer spectroscopy revealed Fe(III) in all samples, although SB, CL and AZTD also contained appreciable Fe(II). Both Fe(II) and Fe(III) were primarily substituted into aluminosilicates, although CL, AZTD and IS also contained Fe(III) oxides. Total iron solubility (defined as the summed concentration of dissolved Fe(II) and Fe(III) measured after 24 h) ranged 14 between 4-12% of the source materials’ iron content, but did not scale with either the surface area or the iron content of the samples. This suggests that other factors such as iron speciation and mineralogy may play a key role in iron solubility. Also, the elevated nitrate concentrations encountered from nitric acid at pH 1 suppressed dissolution of Fe(II) from AZTD, CL and SB particles, which we propose results from the surface-mediated, non-photochemical reduction of nitrate by Fe(II).

  20. Discovery of Brownleeite: a New Manganese Silicide Mineral in an Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Nakamura-Messenger, Keiko; Clemett, Simon J.; Messenger, Scott; Jones, John H.; Palma, Russell L.; Pepin, Robert O.; Klock, Wolfgang; Zolensky, Michael E.; Tatsuoka, Hirokazu

    2011-01-01

    The Earth accretes approximately 40,000 tons of cosmic dust annually, originating mainly from the disintegration of comets and collisions among asteroids. This cosmic dust, also known as interplanetary dust particles (IDPs), is a subject of intense interest since it is made of the original building blocks of our Solar System. Although the specific parent bodies of IDPs are unknown, the anhydrous chondritic-porous IDPs (CP-IDPs) subset has been potentially linked to a cometary source. The CP-IDPs are extremely primitive materials based on their unequilibrated mineralogy, C-rich chemistry, and anomalous isotopic signatures. In particular, some CP-IDPs escaped the thermal, aqueous and impact shock processing that has modified or destroyed the original mineralogy of meteorites. Thus, the CP-IDPs represent some of the most primitive solar system materials available for laboratory study. Most CP-IDPs are comprised of minerals that are common on Earth. However, in the course of an examination of one of the CP-IDPs, we encountered three sub-micrometer sized grains of manganese silicide (MnSi), a phase that has heretofore not been found in nature. In the seminar, we would like to focus on IDP studies and this manganese silicide phase that has been approved as the first new mineral identified from a comet by the International Mineralogical Association (IMA) in 2008. The mineral is named in honour of Donald E. Brownlee, an American astronomer and a founder of the field of cosmic dust research who is the principal investigator of the NASA Stardust Mission that collected dust samples from Comet 81P/Wild-2 and returned them to Earth. Much of our current view and understanding of the early solar system would not exist without the pioneering work of professor Don Brownlee in the study of IDPs.

  1. Clay minerals in primitive meteorites and interplanetary dust 2. Smectites and micas

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Zolensky, M. E.

    1991-01-01

    The classification is briefly summarized of stony meteorites and cosmic dust, and the mineralogy and chemistry is described of serpentine group minerals. The occurrence of smectites and micas in extraterrestrial materials is examined. The characterization of fine grained minerals in meteorites and IDPs relies heavily on electron beam instruments, especially the transmission electron microscope (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites lose their interlayer water and the interlayer partly collapse in the high vacuum of the TEM.

  2. Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations

    NASA Astrophysics Data System (ADS)

    Ryder, C. L.; McQuaid, J. B.; Flamant, C.; Rosenberg, P. D.; Washington, R.; Brindley, H. E.; Highwood, E. J.; Marsham, J. H.; Parker, D. J.; Todd, M. C.; Banks, J. R.; Brooke, J. K.; Engelstaedter, S.; Estelles, V.; Formenti, P.; Garcia-Carreras, L.; Kocha, C.; Marenco, F.; Sodemann, H.; Allen, C. J. T.; Bourdon, A.; Bart, M.; Cavazos-Guerra, C.; Chevaillier, S.; Crosier, J.; Darbyshire, E.; Dean, A. R.; Dorsey, J. R.; Kent, J.; O'Sullivan, D.; Schepanski, K.; Szpek, K.; Trembath, J.; Woolley, A.

    2015-07-01

    The Fennec climate programme aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE (Service des Avions Français Instrumentés pour la Recherche en Environnement) Falcon 20 is described, with specific focus on instrumentation specially developed for and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include (1) the first airborne measurement of dust particles sizes of up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI (Spinning Enhanced Visible Infra-Red Imager) satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in situ observations of processes in SABL clouds showing dust acting as cloud condensation nuclei (CCN) and ice nuclei (IN) at -15 °C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold pool (haboob) issued from deep convection over the Atlas Mountains, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area

  3. Dust exposure and respiratory disease in U. S. coal miners. Doctoral thesis

    SciTech Connect

    Seixas, N.S.

    1990-01-01

    The investigation was carried out by considering the exposure response relationship in a group of 1270 miners whose exposure began in or after 1970 when the regulations took effect. Over a 15 year period the results of the study indicated statistically significant positive associations of cumulative exposure with decrements in forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity (FVC), and symptoms of chronic bronchitis, breathlessness and wheeze with shortness of breath. As a result of the act, these miners were exposed to dust concentrations generally less than 2.0mg/m3. The study suggested that miners entering exposure for the first time in 1970 or later, experienced a rapid initial loss of pulmonary function in relation to their cumulative exposure to dust. The losses were observed in both FVC and FEV1 suggesting that the effect was primarily on lung volumes. Over the following 12 years there was little additional exposure related loss. The study concluded that the regulations have not been completely successful in preventing respiratory effects from exposure to coal mine dust.

  4. Microscopy and Spectroscopy Techniques to Guide Parameters for Modeling Mineral Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Veghte, D. P.; Moore, J. E.; Jensen, L.; Freedman, M. A.

    2013-12-01

    Mineral dust aerosol particles are the second largest emission by mass into the atmosphere and contribute to the largest uncertainty in radiative forcing. Due to the variation in size, composition, and shape, caused by physical and chemical processing, uncertainty exists as to whether mineral dust causes a net warming or cooling effect. We have used Cavity Ring-Down Aerosol Extinction Spectroscopy (CRD-AES), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) to measure extinction cross sections and morphologies of size-selected, non-absorbing and absorbing mineral dust aerosol particles. We have found that microscopy is essential for characterizing the polydispersity of the size selection of non-spherical particles. Through the combined use of CRD-AES, microscopy, and computation (Mie theory and Discreet Dipole Approximation), we have determined the effect of shape on the optical properties of additional species including clay minerals, quartz, and hematite in the sub-micron regime. Our results have shown that calcite can be treated as polydisperse spheres while quartz and hematite need additional modeling parameters to account for their irregularity. Size selection of clay minerals cannot be performed due to their irregular shape, but microscopy techniques can be used to better quantify the particle aspect ratio. Our results demonstrate a new method that can be used to extend cavity ring-down spectroscopy for the measurement of the optical properties of non-spherical particles. This characterization will lead to better aerosol extinction parameters for modeling aerosol optical properties in climate models and satellite retrieval algorithms.

  5. Radiative Energetics of Mineral Dust Aerosols from Ground-Based Measurements

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee; Hansell, Richard A.

    2011-01-01

    Airborne dust aerosols worldwide contribute a significant part to air quality problems and, to some extent, regional climatic issues (e.g., radiative forcing, hydrological cycle, and primary biological productivity in oceans). Evaluating the direct solar radiative effect of dust aerosols is relatively straightforward due in part to the relatively large SIN ratio in broadband irradiance measurements. The longwave (LW) impact, on the other hand, is rather difficult to ascertain since the measured dust signal level (approx.10 W/sq m) is on the same order as the instrumental uncertainties. Although the magnitude of the LW impact is much smaller than that of the shortwave (SW), it can still have a noticeable influence on the energy distribution of Earth-atmosphere system, particularly due to the strong light-absorptive properties commonly found in many terrestrial minerals. The current effort is part of an ongoing research study to perform a global assessment of dust direct aerosol radiative effects (DARE) during major field deployments of key dust source regions worldwide. In this work we present results stemming from two previous field deployments: the 2006 NASA African Monsoon Multidisciplinary Activities and the 2008 Asian Monsoon Years, both utilizing NASA Goddard's mobile ground-based facility. The former study focused on transported Saharan dust at Sal (16.73degN, 22.93degW), Cape Verde along the west coast of Africa while the latter focused on Asian dust at Zhangye (39.082degN, 100.276degE), China near the source between the Taklimakan and Gobi deserts. Due to the compelling variability in spatial and temporal scale of dust properties during field experiments, a deterministic I-D radiative transfer model constrained by local measurements (i.e., spectral photometry/interferometry and lidar for physical/microphysical, mineralogy, and single-scattering properties) is employed to evaluate dust's local instantaneous SW/LW DARE both at the surface and at the top of

  6. Respirable coal dust exposure and respiratory symptoms in South-African coal miners: A comparison of current and ex-miners

    SciTech Connect

    Naidoo, R.N.; Robins, T.G.; Seixas, N.; Lalloo, U.G.; Becklake, M.

    2006-06-15

    Dose-response associations between respirable dust exposure and respiratory symptoms and between symptoms and spirometry outcomes among currently employed and formerly employed South-African coal miners were investigated. Work histories, interviews, and spirometry and cumulative exposure were assessed among 684 current and 212 ex-miners. Results: Lower prevalences of symptoms were found among employed compared with ex-miners. Associations with increasing exposure for symptoms of phlegm and past history of tuberculosis were observed, whereas other symptom prevalences were higher in the higher exposure categories. Symptomatic ex-miners exhibited lower lung-function compared to the nonsymptomatic. Compared with published data, symptoms rates were low in current miners but high in ex-miners. Although explanations could include the low prevalence of smoking and/or reporting/selection bias, a 'Survivor' and/or a 'hire' effect is more likely, resulting in an underestimation of the dust-related effect.

  7. Mineralogical, chemical, and optical interrelationships of mineral dusts from desert source regions

    NASA Astrophysics Data System (ADS)

    Engelbrecht, J. P.; Moosmüller, H.; Pincock, S.; Jayanty, J.; Casuccio, G.

    2013-12-01

    The goal of the project was to provide information on the mineralogical, chemical and physical interrelationships of re-suspended mineral dust samples collected from global dust sources. Surface soil samples were previously collected from more than 64 desert sites, including the southwestern USA (12), Mali (3), Chad (3), Morocco (1), Canary Islands (8), Cape Verde (1), Djibouti (1), Afghanistan (3), Iraq (6), Kuwait (5), Qatar (1), UAE (1), Serbia (3), China (5), Namibia (3), Botswana (4), Australia (3), and Chile (1). The < 38 μm sieved fraction of each sample was re-suspended in an entrainment facility, from which the airborne mineral dust could be sampled and analyzed. Instruments integrated into the entrainment facility included two PM10 and two PM2.5 filter samplers, a beta attenuation gauge for the continuous measurement of PM10 and PM2.5 particulate mass fractions, an aerodynamic particle size (APS) analyzer, and a three wavelength (405, 532, 781nm) photoacoustic instrument with integrating reciprocal nephelometer for monitoring aerosol absorption and scattering coefficients during the re-suspension process. Filter sample media included Teflon membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore filters for individual particle analysis by Scanning Electron Microscopy (SEM). The < 38 μm sieved fractions were also analyzed by X-ray diffraction for their mineral content while the > 38 μm, < 125 μm fractions were further mineralogically characterized by optical microscopy. We will be presenting results on the optical measurements, showing the relationship between single scattering albedo (SSA) at three different wavelengths, and chemical as well as mineralogical content and interrelationships, of the entrained dust samples. Information from this data base will be available for research in global climate, remote sensing, visibility, and health (medical geology).

  8. Chemical fate and settling of mineral dust in surface seawater after atmospheric deposition observed from dust seeding experiments in large mesocosms

    NASA Astrophysics Data System (ADS)

    Desboeufs, K.; Leblond, N.; Wagener, T.; Bon Nguyen, E.; Guieu, C.

    2014-10-01

    We report here the elemental composition of sinking particles in sediment traps and in the water column following four artificial dust seeding experiments (each representing a flux of 10 g m-2). Dry or wet dust deposition were simulated during two large mesocosms field campaigns that took place in the coastal water of Corsica (NW Mediterranean Sea) representative of oligotrophic conditions. The dust additions were carried out with fresh or artificially aged dust (i.e., enriched in nitrate and sulfate by mimicking cloud processing) for various biogeochemical conditions, enabling us to test the effect of these parameters on the chemical composition and settling of dust after deposition. The rates and mechanisms of total mass, particulate organic carbon (POC) and chemical elements (Al, Ba, Ca, Co, Cu, Fe, K, Li, Mg, Mn, Mo, N, Nd, P, S, Sr and Ti) transfer from the mesocosm surface to the sediment traps installed at the base of the mesocosms after dust deposition show that (1) 15% of the initial dust mass was dissolved in the water column in the first 24 h after seeding. Except for Ca, S and N, the elemental composition of dust particles was constant during their settling, showing the relevance of using interelemental ratios, such as Ti/Al as proxy of lithogenic fluxes. (2) Whatever the type of seeding (using fresh dust to simulate dry deposition or artificially aged dust to simulate wet deposition), the particulate phase both in the water column and in the sediment traps was dominated by dust particles. (3) Due to the high Ba content in dust, Ba/Al cannot be used as productivity proxy in the case of high dust input in the sediment traps. Instead, our data suggests that the ratio Co/Al could be a good productivity proxy in this case. (4) After 7 days, between 30 and 68% of added dust was still in suspension in the mesocosms. This difference in the dust settling was directly associated with a difference in POC export, since POC fluxes were highly correlated to dust

  9. Size distributions of mineral aerosols and dust emission flux observed over Horqin Sandy Land area in northern China

    NASA Astrophysics Data System (ADS)

    Li, X.; Zhang, H. S.

    2013-01-01

    Size distribution of mineral aerosols is of primary importance in determining their residence time in atmosphere, transport patterns, removal mechanisms as well as their effects on climate and human health. This study aims to obtain dust particle size distribution and size-resolved dust emission flux under different weather conditions over a sandy land area in northern China (Horqin Sandy Land, Inner Mongolia), using the observational data from Horqin sandstorm monitoring station in the spring of 2010 and 2012. Dust (PM20) mass concentration was measured by a 10-stage quartz crystal microbalance (QCM) cascade impactor. The statistical results indicate that finer dust particles (r ≤ 1.0 μm) take a large proportion of all PM20 concentration under clear-day conditions, while coarser dust particles (r ≥ 2.5 μm) concentration increased under dust-day conditions, with the peak occurring between 4-7 μm. The dust particle size distributions during the pre-dust-emission and dust-emission periods of a dust event on 7 April 2012 have similar features to the statistical results. During the dust event, the magnitude of dust emission flux of all sizes increased about one or two orders (0.1-10 μg m-2 s-1) as u* increase from 0.54 to 1.29 m s-1. The maximum total F value was about 43.0 μg m-2 s-1 and the maximum size-resolved F(Ddi) is 12.3 μg m-2 s-1 in 0.3-0.45 μm size bin when u* is 1.29 m s-1. Dust advection has effects on airborne dust size distribution, making the proportion of dust particles of different sizes more uniform, as observed in a non-local dust event on 19 April 2012.

  10. Heterogeneous nucleation as a potential sulphate-coating mechanism of atmospheric mineral dust particles and implications of coated dust on new particle formation

    NASA Astrophysics Data System (ADS)

    Korhonen, H.; Napari, I.; Timmreck, C.; VehkamäKi, H.; Pirjola, L.; Lehtinen, K. E. J.; Lauri, A.; Kulmala, M.

    2003-09-01

    The plausibility of heterogeneous conucleation of water, sulphuric acid, and ammonia as a pathway leading to soluble coating of atmospheric mineral dust is investigated. In addition, the effect of such sulphate-coated dust on the formation and growth of atmospheric aerosol particles is addressed. The simulated new particle formation mechanism is ternary nucleation of water, sulphuric acid, and ammonia vapors, while in the condensational growth process the effect of condensable organic vapor is also studied. The results indicate that soluble coating of dust by heterogeneous nucleation can occur at atmospheric sulphuric acid concentrations. In addition, the simulations show that homogeneous ternary nucleation and subsequent growth are decoupled. Although observed (or even higher) dust concentrations are unable to inhibit new particle formation, coated dust particles acting as condensation and coagulation sinks can prevent the growth of newly formed particles to detectable sizes. This is particularly true in desert areas, where organic vapor concentrations are low.

  11. The competition between mineral dust and soot ice nuclei in mixed-phase clouds (Invited)

    NASA Astrophysics Data System (ADS)

    Murray, B. J.; Atkinson, J.; Umo, N.; Browse, J.; Woodhouse, M. T.; Whale, T.; Baustian, K. J.; Carslaw, K. S.; Dobbie, S.; O'Sullivan, D.; Malkin, T. L.

    2013-12-01

    The amount of ice present in mixed-phase clouds, which contain both supercooled liquid water droplets and ice particles, affects cloud extent, lifetime, particle size and radiative properties. The freezing of cloud droplets can be catalysed by the presence of aerosol particles known as ice nuclei. In this talk our recent laboratory and global aerosol modelling work on mineral dust and soot ice nuclei will be presented. We have performed immersion mode experiments to quantify ice nucleation by the individual minerals which make up desert mineral dusts and have shown that the feldspar component, rather than the clay component, is most important for ice nucleation (Atkinson et al. 2013). Experiments with well-characterised soot generated with eugenol, an intermediate in biomass burning, and n-decane show soot has a significant ice nucleation activity in mixed-phase cloud conditions. Our results for soot are in good agreement with previous results for acetylene soot (DeMott, 1990), but extend the efficiency to much higher temperatures. We then use a global aerosol model (GLOMAP) to map the distribution of soot and feldspar particles on a global basis. We show that below about -15oC that dust and soot together can explain most observed ice nuclei in the Earth's atmosphere, while at warmer temperatures other ice nuclei types are needed. We show that in some regions soot is the most important ice nuclei (below -15oC), while in others feldspar dust dominates. Our results suggest that there is a strong anthropogenic contribution to the ice nuclei population, since a large proportion of soot aerosol in the atmosphere results from human activities. Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Carslaw, K. S., Whale, T. F., Baustian, K. J., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds, Nature, 10.1038/nature12278, (2013). Demott, P. J. 1990. An Exploratory-Study of Ice Nucleation by Soot

  12. Loss of lung function associated with exposure to silica dust and with smoking and its relation to disability and mortality in South African gold miners.

    PubMed Central

    Hnizdo, E

    1992-01-01

    The data from a lung function study on 2209 white 45-54 year old South African gold miners in 1968-71 and at a five year follow up examination, were analysed to establish the actual loss of lung function associated with exposure to silica dust and with smoking. Ex-smokers were excluded from the analysis. Of the remaining 1625 subjects, 1249 had the five year follow up test of lung function. The estimated excess loss of lung function for a 50 year old gold miner, associated with 24 years of underground dust exposure of an average respirable dust concentration of 0.30 mg m-3 (14.4 ghm-3) was 236 ml of FEV1 (95% confidence interval (95% CI 134-337) and 217 ml of FVC (95% CI 110-324). By comparison, the effect of smoking one packet of cigarettes a day over 30 years was associated with an estimated loss of 552 ml of FEV1 (95% CI 461-644) and 335 ml of FVC (95% CI 170-500). The cumulative dust exposure was not associated with the longitudinal loss of FEV1 or FVC when the initial FEV1 and FVC were adjusted in the models. According to the predicted values, however, gold miners appear to have a greater loss of lung function from 50 to 55 years of age than that predicted for a general population. PMID:1322158

  13. Measurement of mixed biomass burning and mineral dust aerosol in the thermal infrared

    NASA Astrophysics Data System (ADS)

    Koehler, C. H.; Trautmann, T.; Lindermeir, E.

    2009-03-01

    From January 19th to February 7th, 2008, we installed a Fourier transform infrared spectrometer (FTIR) at Praia Airport on the island of Santiago, Cape Verde. Our goal was to measure the combined radiative effect of biomass burning aerosol and mineral dust usually observed there during that time of the year, when mineral dust emerging from the Sahara mixes with biomass burning aerosol transported north-westwards from the Sahelian region. Our measurements were part of the Saharan Mineral Dwst Experiment 2 (SAMUM 2) funded by the German Research Foundation (DFG) as continuation of the SAMUM field experiment in Morocco in 2006. SAMUM 2 is a joint venture of several German research institutes and universities and included both ground based as well as airborne measurements with the DLR Falcon research aircraft. The ground based instrumentation included spectrometers for visible and thermal infrared downwelling radiation, sun photometers, LIDAR and particle impactors while the Falcon was equipped with LIDAR and several instruments for aerosol analysis and sample return. A comparison of the FTIR measurements with radiative transfer simulations yields the expected aerosol forcing in the atmospheric window region after application of a suitable calibration method.

  14. Ice Nucleation of Bare and Sulfuric Acid-coated Mineral Dust Particles and Implication for Cloud Properties

    SciTech Connect

    Kulkarni, Gourihar R.; Sanders, Cassandra N.; Zhang, Kai; Liu, Xiaohong; Zhao, Chun

    2014-08-27

    Ice nucleation properties of different dust species coated with soluble material are not well understood. We determined the ice nucleation ability of bare and sulfuric acid coated mineral dust particles as a function of temperature (-25 to -35 deg C) and relative humidity with respect to water (RHw). Five different mineral dust species: Arizona test dust (ATD), illite, montmorillonite, quartz and kaolinite were dry dispersed and size-selected at 150 nm and exposed to sulfuric acid vapors in the coating apparatus. The condensed sulfuric acid soluble mass fraction per particle was estimated from the cloud condensation nuclei activated fraction measurements. The fraction of dust particles nucleating ice at various temperatures and RHw was determined using a compact ice chamber. In water-subsaturated conditions, compared to bare dust particles, we found that only coated ATD particles showed suppression of ice nucleation ability while other four dust species did not showed the effect of coating on the fraction of particles nucleating ice. The results suggest that interactions between the dust surface and sulfuric acid vapor are important, such that interactions may or may not modify the surface via chemical reactions with sulfuric acid. At water-supersaturated conditions we did not observed the effect of coating, i.e. the bare and coated dust particles had similar ice nucleation behavior.

  15. Atmospheric delivery of anthropogenic bioavailable iron from mineral dust to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2015-12-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean. However, our modeled Fe solubility was significantly lower than that deduced from observations over the South Atlantic east downwind from the Patagonian dust source regions. Our modeled Fe solubility for dry deposition over the Atlantic is in good agreement the measurement, while that for wet deposition is significantly lower than the measurement. Our model results suggest that human activities contribute to about half of the soluble Fe supply to a significant portion of the oceans in the Northern Hemisphere, while their contribution to oceans in the high latitude remains highly uncertain

  16. Controls on mineral dust emissions at four arid locations in the western USA

    NASA Astrophysics Data System (ADS)

    Engelbrecht, Johann P.; Gillies, John A.; Etyemezian, Vicken; Kuhns, Hampden; Baker, Sophie E.; Zhu, Dongzi; Nikolich, George; Kohl, Steven D.

    Dust emission measurements from unique military sources, including tracked and wheeled military vehicles, low flying rotary-winged aircraft, and artillery backblast, were conducted in the course of four field campaigns in 2005-2008, at Yuma Proving Ground (YPG) in Arizona (twice), Yakima Test Center (YTC) in Washington State, and Ft. Carson in Colorado. This paper reports on the observed relationships between levels of dust emission, and the mineralogy, particle size, and chemical composition of the surface sediment and associated airborne mineral dust. We propose a mechanism for the generation of fine particulate matter, providing an explanation for high emissions in certain regions. PM10 (particulate matter with aerodynamic diameter of <10 μm) and PM2.5 (particulate matter with aerodynamic diameter of <2.5 μm) filter as well as bulk samples were collected for laboratory analysis in the course of the field campaigns. Analytical techniques applied include X-ray diffraction, Scanning Electron Microscopy, laser particle size analysis, as well as X-ray fluorescence spectrometry, Ion Chromatography, and Automated Colorimetry. Previous work has shown YTC has higher dust emission factors than YPG and Ft. Carson. The results presented in this paper demonstrate that the high PM10 and PM2.5 emissions measured at YTC can be explained by the high silt and low clay content of the surface sediment, attributed to glacial loess. In the other test areas, the abrasion of microscopic clay and oxide coatings, from and by silicate mineral grains, is considered a factor in the generation of fine particulate matter.

  17. The heterogeneous chemical kinetics of NO3 on atmospheric mineral dust surrogates.

    PubMed

    Karagulian, Federico; Rossi, Michel J

    2005-09-01

    Uptake experiments of NO3 on mineral dust powder were carried out under continuous molecular flow conditions at 298 +/- 2 K using the thermal decomposition of N2O5 as NO3 source. In situ laser detection using resonance enhanced multiphoton ionization (REMPI) to specifically detect NO2 and NO in the presence of N2O5, NO3 and HNO3 was employed in addition to beam-sampling mass spectrometry. At [NO3] = (7.0 +/- 1.0) x 10(11) cm(-3) we found a steady state uptake coefficient gamma(ss) ranging from (3.4 +/- 1.6) x 10(-2) for natural limestone to (0.12 +/- 0.08) for Saharan Dust with gamma(ss) decreasing as [NO3] increased. NO3 adsorbed on mineral dust leads to uptake of NO2 in an Eley-Rideal mechanism that usually is not taken up in the absence of NO3. The disappearance of NO3 was in part accompanied by the formation of N2O5 and HNO3 in the presence of NO2. NO3 uptake performed on small amounts of Kaolinite and CaCO3 leads to formation of some N2O5 according to NO((3ads)) + NO(2(g)) --> N2O(5(ads)) --> N2O(5(g)). Slow formation of gas phase HNO3 on Kaolinite, CaCO3, Arizona Test Dust and natural limestone has also been observed and is clearly related to the presence of adsorbed water involved in the heterogeneous hydrolysis of N2O(5(ads)).

  18. Carbonaceous aerosols and mineral dust in atmospheric outflow from the Indo-Gangetic Plain

    NASA Astrophysics Data System (ADS)

    Sarin, M.; Srinivas, B.; Rengarajan, R.

    2012-12-01

    Atmospheric carbonaceous aerosols and mineral dust over south and south-east Asia has been a subject of major debate over the past two decades because of their potential impact on the regional air quality and climate forcing. A comprehensive study through ground-based measurements and data-base for aerosol chemical composition (involving both organic and inorganic constituents) is, thus, essential to constrain the large uncertainties associated with the climate impact. Our systematic study from a downwind site (Kharagpur: 22.02N, 87.11E) in the Indo-Gangetic Plain (IGP) suggests large temporal variability in the atmospheric mass concentrations of mineral dust, organic and elemental carbon (OC, EC), water-soluble organic carbon (WSOC) and inorganic species (WSIS). This is attributed to seasonally varying anthropogenic emissions, their source strength, boundary layer dynamics, secondary aerosol formation and long-range transport of mineral dust from desert regions. Based on diagnostic ratios [OC/EC ≈ 7.0 ± 2.2, WSOC/OC ≈ 0.6 and K+/EC ≈ 0.48 ± 0.17], we document biomass burning emissions (wood-fuel and post-harvest agricultural-waste burning) as a major source of carbonaceous aerosols. The characteristic ratios: nss-SO42-/EC (3.9 ± 2.1), nss-SO42-/OC (0.61 ± 0.46), high abundance of SO42- (6.9 - 25.3 μg m-3) and SO42-/ΣWSIS = 45 - 77 % in the outflow provide better assessment of aerosol optical properties. The subsequent downwind transport of pollutants from the IGP significantly influences the chemical composition of aerosols over the Bay of Bengal. The dominance of aerosol SO42- in the marine atmospheric boundary layer (MABL) is evident from the wide-spread depletion of chloride with respect to sea-salt composition. The Ca/Al and Fe/Al ratios in the IGP-outflow, used as a proxy for the long-range transport of mineral dust, are consistent with those in the MABL. The mass closure for PM2.5 composition suggests that contribution of mineral dust (20

  19. High-resolution mineral dust and sea ice proxy records from the Talos Dome ice core

    NASA Astrophysics Data System (ADS)

    Schüpbach, S.; Federer, U.; Kaufmann, P. R.; Albani, S.; Barbante, C.; Stocker, T. F.; Fischer, H.

    2013-12-01

    In this study we report on new non-sea salt calcium (nssCa2+, mineral dust proxy) and sea salt sodium (ssNa+, sea ice proxy) records along the East Antarctic Talos Dome deep ice core in centennial resolution reaching back 150 thousand years (ka) before present. During glacial conditions nssCa2+ fluxes in Talos Dome are strongly related to temperature as has been observed before in other deep Antarctic ice core records, and has been associated with synchronous changes in the main source region (southern South America) during climate variations in the last glacial. However, during warmer climate conditions Talos Dome mineral dust input is clearly elevated compared to other records mainly due to the contribution of additional local dust sources in the Ross Sea area. Based on a simple transport model, we compare nssCa2+ fluxes of different East Antarctic ice cores. From this multi-site comparison we conclude that changes in transport efficiency or atmospheric lifetime of dust particles do have a minor effect compared to source strength changes on the large-scale concentration changes observed in Antarctic ice cores during climate variations of the past 150 ka. Our transport model applied on ice core data is further validated by climate model data. The availability of multiple East Antarctic nssCa2+ records also allows for a revision of a former estimate on the atmospheric CO2 sensitivity to reduced dust induced iron fertilisation in the Southern Ocean during the transition from the Last Glacial Maximum to the Holocene (T1). While a former estimate based on the EPICA Dome C (EDC) record only suggested 20 ppm, we find that reduced dust induced iron fertilisation in the Southern Ocean may be responsible for up to 40 ppm of the total atmospheric CO2 increase during T1. During the last interglacial, ssNa+ levels of EDC and EPICA Dronning Maud Land (EDML) are only half of the Holocene levels, in line with higher temperatures during that period, indicating much reduced sea

  20. The immersion freezing behavior of the mixture of mineral dust and biological substances

    NASA Astrophysics Data System (ADS)

    Augustin, S.; Schneider, J.; Schmidt, S.; Niedermeier, D.; Ebert, M.; Voigtländer, J.; Stratmann, F.; Wex, H.

    2013-12-01

    Ice nucleation in the atmosphere has been observed at temperatures higher than -20°C (e.g. Kanitz et al., 2011). In contrast, laboratory studies showed that the most abundant atmospheric ice nuclei (IN), i.e., mineral dust particles, are ice active at much lower temperatures (e.g. Murray et al., 2012). Biological particles such as bacteria or pollen nucleate ice at temperatures similar to those observed in the atmosphere. However, their numbers seem to be too small to explain atmospheric ice nucleation (Hoose et al., 2010). Recent studies suggest, that ice nucleation active (INA) macromolecules, i.e. protein complexes in the case of bacteria (e.g. Wolber et al., 1986), and most likely polysaccharides in the case of pollen (Pummer et al., 2012), which are responsible for the freezing, maintain their nucleating ability even when they are separated from their original carriers (bacterial cell or pollen grain, Hartmann et al., 2013; Augustin et al., 2012). This opens the possibility of accumulation of such INA macromolecules in e.g. soils and the resulting particles could be an internal mixture of mineral dust and INA macromolecules. If such biological IN containing soil particles are then dispersed into the atmosphere due to e.g. wind erosion or agricultural processes they could induce ice nucleation at temperatures higher then -20°C. To explore this hypothesis, we investigated the ice nucleation behavior of mineral dust particles internally mixed with INA macromolecules. Specifically, we mixed pure mineral dust (Illit) with INA biological material (SNOMAX and birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). Augustin, S., Hartmann, S., Pummer, B., Grothe, H., Niedermeier, D., Clauss, T., Voigtländer, J., Tomsche, L, Wex, H. and Stratmann, F., Atmos. Chem. Phys. Discuss., 12, 32911-32943, 2012. Hartmann, S., Augustin, S.,D. Niedermeier, J

  1. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2015-08-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. Here, we, for the first time, interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. We firstly examined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). We then constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water, by using acidity as a master variable. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean (i.e., 1-2 orders of magnitude lower Fe solubility in North African- than combustion-influenced aerosols). The model results show a positive relationship between Fe solubility and water soluble organic carbon (WSOC)/Fe molar ratio, which is consistent with previous field measurements. We estimated that deposition of soluble Fe to the ocean increased from 0.05-0.07 Tg Fe yr-1 in preindustrial era to 0.11-0.12 Tg Fe yr-1 in present days, due to air pollution. Over the High Nitrate Low Chlorophyll (HNLC) regions of the ocean, the modeled Fe solubility remains low for

  2. Impact of surface roughness and soil texture on mineral dust emission fluxes modeling

    NASA Astrophysics Data System (ADS)

    Menut, Laurent; PéRez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, StéPhane

    2013-06-01

    Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

  3. Impact of Surface Roughness and Soil Texture on Mineral Dust Emission Fluxes Modeling

    NASA Technical Reports Server (NTRS)

    Menut, Laurent; Perez, Carlos; Haustein, Karsten; Bessagnet, Bertrand; Prigent, Catherine; Alfaro, Stephane

    2013-01-01

    Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

  4. Geochemical Evidence for Periods of Increased Mineral Dust Deposition in Patagonian Peat Bogs Since the Last Deglaciation

    NASA Astrophysics Data System (ADS)

    Vanneste, H.; De Vleeschouwer, F.; Mattielli, N. D.; Vanderstraeten, A.; von Scheffer, C.; Piotrowska, N.; Coronato, A.; Le Roux, G.

    2013-12-01

    Atmospheric mineral dust plays an important role in the earth's climate system, influencing atmospheric parameters such as cloud condensation as well as biogeochemical cycles, affecting atmospheric CO2 levels. Antarctic ice core records show that mineral dust deposition has varied in the Southern Hemisphere over glacial-interglacial stages, suggesting major changes in atmospheric circulation. Nevertheless, to make predictions for the near future possible, a better understanding of atmospheric dust load and transport variability in the recent past, is essential. Ombrotrophic peat bogs have proven to provide excellent records of atmospheric dust deposition for the Holocene as their accumulation rates are higher than any other archive. Hence two ombrotrophic peat bogs, located southwest (Karukinka) and southeast (Harberton) on Isla Grande de Tierra del Fuego, were sampled to investigate dust-palaeoclimatic interactions in southern South America since the last deglaciation. Here we present a detailed geochemical (major, trace elements and Nd isotopes) record for both sites. The base of the peat sequences in Karukinka and Harberton were dated by 14C at ca. 8,000 cal yr BP and ca. 16,500 cal yr BP, respectively. The distribution of trace elemental (Sc, REE) concentrations within the cores indicates, besides tephra layers, episodes of increased mineral dust deposition at Harberton and Karukinka. The glacial-interglacial transition can be observed in the Harberton record (at ca. 11,500 cal yr BP), marked by a drop in the dust flux from 102 g/m2/yr to 10 g/m2/yr. The most significant episode of mineral dust deposition at Karukinka is concentrated around 1,600 cal yr BP with a maximum dust flux of 108 g/m2/yr. Its neodymium isotopic signature of -1 suggests crustal admixing, compared to the ɛNd values of ˜2, for both tephra layers.

  5. Opaque minerals of the lunar rocks and dust from mare tranquillitatis.

    PubMed

    Ramdohr, P; Goresey, A E

    1970-01-30

    The opaque minerals in the lunar rocks 10047, 10050, 10057, 10059, 10068 and in the dust were studied. Rock 10047 contains ilmenite as a main component besides Al-bearing chromian ulvöspinel, a new Ti, Fe, Zr, Y, Ca silicate, troilite, cobaltian alpha Fe, minor hafnian baddeleyite and dysanalyte. Dysanalyte contains Ca, Ti, and Fe as major elements and shows concentrations (rare earth elements together approximately 10 percent) of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Hf, Y, and Zr plus traces of Nb, Ba, and Na. The chemistry of ilmenite in the igneous rocks shows no appreciable variations. A new mineral of the solid solution series MgTi(2)O(5)-FeTi(2)O(5) has also been encountered in the polymict breccias. The microbreccias and the fines contain meteorite debris indicating an impact origin.

  6. Characterization of ^{239,240}Pu Radionuclide Adsorption to Soil Particles and Mineral Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Tatro, D. P.; Arimoto, R.; McMillan, N. J.; Barnes, M.

    2006-12-01

    The release of ^{239,240}Pu into the environment by nuclear weapons testing 50 years ago initiated the cyclic mobilization of Pu-contaminated soil particles via the resuspension of dust resulting in a widespread distribution of Pu and other radionuclides. It is unclear what enables the aeolian transport of Pu in the environment; plausible hypotheses of Pu binding to dust and soil particles include Pu adsorption to iron oxides/hydroxides, organic acids, or silicate minerals such as clays. To investigate the connections between surface soils, dust and radionuclides, samples of soil and/or dust were collected from the Project Gnome Site in Eddy County, NM, the Jemez Mountains near Los Alamos, NM, and two 50-year old attics and wind-blown dust in Big Spring, TX. This study tests the hypothesis that Pu is adsorbed onto Fe oxides and hydroxides that coat dust/soil particles. The samples are generally low in organic carbon (0.2 - 4.8%, except for the unburned Los Alamos sample at 9.4%), as measured by LOI (Loss On Ignition) at 360 °C. The citrate-bicarbonate-dithionite method (CDB) of Fe oxide removal, first proposed by Mehra and Jackson in 1960, was used to selectively extract Fe oxides from the samples while leaving silicate Fe intact. Chemical digestion of each sample creates two fractions, the extracted supernatant and a solid pellet residue. If the Pu were associated with Fe oxides, then Fe and Pu should both be selectively removed from the bulk sample during the CBD process, leaving the pellet depleted in Fe and Pu and the supernatant enriched. For Fe, this was confirmed by scanning electron microscope and petrographic analyses. Preliminary radiochemical analyses of Pu activity also verify this hypothesis. Pu activity is significantly lower in pellets than bulk samples (Pu activitypellet/Pu activitybulk average = 0.07, range 0.02-0.12); Pu activity in supernatants is significantly higher than in bulk samples (Pu activitysupernatant/Pu activitybulk average = 4

  7. Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

    NASA Astrophysics Data System (ADS)

    Osada, K.; Ura, S.; Kagawa, M.; Mikami, M.; Tanaka, T. Y.; Matoba, S.; Aoki, K.; Shinoda, M.; Kurosaki, Y.; Hayashi, M.; Shimizu, A.; Uematsu, M.

    2014-01-01

    Recent ground networks and satellite remote-sensing observations have provided useful data related to spatial and vertical distributions of mineral dust particles in the atmosphere. However, measurements of temporal variations and spatial distributions of mineral dust deposition fluxes are limited in terms of their duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition using wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008-December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyser. Wet and dry deposition fluxes of mineral dusts were both high in spring and low in summer, showing similar seasonal variations to frequency of aeolian dust events (Kosa) in Japan. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m-2 yr-1) and at Cape Hedo (1.7 g m-2 yr-1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (> 60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m-2 yr-1) and at Cape Hedo (2.0 g m-2 yr-1) as average values in 2009 and 2010. The average ratio of wet and dry deposition fluxes was the highest at Toyama (3.3) and the lowest at Hedo (0.82), showing a larger contribution of the dry process at western sites, probably because of the distance from desert source regions and because of the effectiveness of the wet process in the dusty season. Size distributions of refractory dust particles were obtained using four-stage filtration: > 20, > 10, > 5, and > 1 μm diameter. Weight fractions

  8. Chemical Evolution of Mineral Dust and Its Impact on Radiative Forcing in East Asia during 2006-2010

    NASA Astrophysics Data System (ADS)

    Fu, J. S.; DONG, X.; Huang, K.

    2014-12-01

    Arid regions and deserts in China and Mongolia are two of the main terrestrial sources of airborne dust, with major contribution from Taklamakan and Gobi deserts which can travel to China, Japan, Taiwan and even across Pacific Ocean to US and around north hemisphere. While China has been one of the most rapid-developing countries during the past decade, it also contributes intensive anthropogenic emissions including SO2 and NOx. Critical uncertainties remain regarding the chemical transformation of dust components during the transport with reactions involving these anthropogenic pollutants, which may significantly alter the optical properties and size distribution of mineral dust, and finally affect regional climate. In this study, we implemented heterogeneous reactions for dust particles into the WRF/CMAQ modeling system, and investigate the chemical evolution of mineral dust during the transport pathway. Integrating the dust-blown scheme of CMAQ, we also probe into the inter-annual changes of dust emission from East Asia, and the radiative forcing changes due to dust particles for 5 consecutive years from 2006-2010.

  9. Multi-year model simulations of mineral dust distribution and transport over the Indian subcontinent during summer monsoon seasons

    NASA Astrophysics Data System (ADS)

    Sijikumar, S.; Aneesh, S.; Rajeev, K.

    2016-08-01

    Aerosol distribution over the Arabian Sea and the Indian subcontinent during the northern hemispheric summer is dominated by mineral dust transport from the West Asian desert regions. The radiative impact of these dust plumes is expected to have a prominent role in regulating the Asian Summer Monsoon circulation. While satellite observations have provided information in the spatial distribution of aerosols over the oceanic regions during the season, their utility over the land is rather limited. This study examines the transport of mineral dust over the West Asian desert, the Indian subcontinent and the surrounding oceanic regions during the summer monsoon season with the help of a regional scale model, WRF-Chem. Geographical locations of prominent dust sources, altitude ranges of mineral dust transport and their inter-annual variations are examined in detail. Multi-year model simulations were carried out during 2007 to 2012 with a model integration from 15 May to 31 August of each year. Six-year seasonal mean (June to August) vertically integrated dust amount from 1000 to 300 hPa level shows prominent dust loading over the eastern parts of Arabian desert and the northwestern part of India which are identified as two major sources of dust production. Large latitudinal gradient in dust amount is observed over the Arabian Sea with the largest dust concentration over the northwestern part and is primarily caused by the prevailing northwesterly wind at 925 hPa level from the Arabian desert. The model simulations clearly show that most of the dust distributed over the Indo-Gangetic plane originates from the Rajasthan desert located in the northwestern part of India, whereas dust observed over the central and south peninsular India and over the Arabian Sea are mainly transported from the Arabian desert. Abnormal dust loading is observed over the north Arabian Sea during June 2008. This has been produced as a result of the low pressure system (associated with the onset of

  10. Wet and dry deposition of mineral dust particles in Japan: factors related to temporal variation and spatial distribution

    NASA Astrophysics Data System (ADS)

    Osada, K.; Ura, S.; Kagawa, M.; Mikami, M.; Tanaka, T. Y.; Matoba, S.; Aoki, K.; Shinoda, M.; Kurosaki, Y.; Hayashi, M.; Shimizu, A.; Uematsu, M.

    2013-08-01

    Data of temporal variations and spatial distributions of mineral dust deposition fluxes are very limited in terms of duration, location, and processes of deposition. To ascertain temporal variations and spatial distributions of mineral dust deposition by wet and dry processes, weekly deposition samples were obtained at Sapporo, Toyama, Nagoya, Tottori, Fukuoka, and Cape Hedo (Okinawa) in Japan during October 2008-December 2010 using automatic wet and dry separating samplers. Mineral dust weights in water-insoluble residue were estimated from Fe contents measured using an X-ray fluorescence analyzer. For wet deposition, highest and lowest annual dust fluxes were found at Toyama (9.6 g m-2 yr-1) and at Cape Hedo (1.7 g m-2 yr-1) as average values in 2009 and 2010. Higher wet deposition fluxes were observed at Toyama and Tottori, where frequent precipitation (>60% days per month) was observed during dusty seasons. For dry deposition among Toyama, Tottori, Fukuoka, and Cape Hedo, the highest and lowest annual dust fluxes were found respectively at Fukuoka (5.2 g m-2 yr-1) and at Cape Hedo (2.0 g m-2 yr-1) as average values in 2009 and 2010. Although the seasonal tendency of the monthly dry deposition amount roughly resembled that of monthly days of Kosa dust events, the monthly amount of dry deposition was not proportional to monthly days of the events. Comparison of dry deposition fluxes with vertical distribution of dust particles deduced from Lidar data and coarse particle concentrations suggested that the maximum dust layer height or thickness is an important factor for controlling the dry deposition amount after long-range transport of dust particles. Size distributions of refractory dust particles were obtained using four-stage filtration: >20, >10, >5, and >1 μm diameter. Weight fractions of the sum of >20 μm and 10-20 μm (giant fraction) were higher than 50% for most of the event samples. Irrespective of the deposition type, the giant dust fractions were

  11. Statistical estimation of mineral age by K-Ar method

    SciTech Connect

    Vistelius, A.B.; Drubetzkoy, E.R.; Faas, A.V. )

    1989-11-01

    Statistical estimation of age of {sup 40}Ar/{sup 40}K ratios may be considered a result of convolution of uniform and normal distributions with different weights for different minerals. Data from Gul'shad Massif (Nearbalkhash, Kazakhstan, USSR) indicate that {sup 40}Ar/{sup 40}K ratios reflecting the intensity of geochemical processes can be resolved using convolutions. Loss of {sup 40}Ar in biotites is shown whereas hornblende retained the original content of {sup 40}Ar throughout the geological history of the massif. Results demonstrate that different estimation methods must be used for different minerals and different rocks when radiometric ages are employed for dating.

  12. Transport of mineral dust to Nepal Climate Observatory - Pyramid (5079 m a.s.l., South Himalayas)

    NASA Astrophysics Data System (ADS)

    Duchi, Rocco; Cristofanelli, Paolo; Marinoni, Angela; Calzolari, Francescopiero; Decesari, Stefano; Laj, Paolo; Vuillermoz, Elisa; Sprenger, Michael; Bonasoni, Paolo

    2010-05-01

    Desert dust is one of the greatest sources of natural aerosol in atmosphere, representing about 37% of the total (natural and anthropogenic) emission of atmospheric primary aerosols. Mineral dust can impact climate through many complex processes, i.e. by scattering and absorbing solar and infrared radiation and by affecting the variability of cloud aerosol optical properties. Moreover, mineral dust can also affect the concentrations of other climate-altering species (e.g. surface ozone) in troposphere. South Asia is a region frequently affected by major dust transport from Africa and Asia. In particular, these "dust clouds" can reach the Himalayas also mixed with the heavy anthropogenic pollution present within the so-called Asian Brown Cloud. With the purpose to define the frequency of long-range mineral dust transport towards the Himalayan range and to evaluate their influence on the atmospheric aerosol background level, in this work we analyse the first 2-year (from March 2006 to February 2008) of coarse (Dp > 1 micron) aerosol number concentration observed at the WMO - GAW station "Nepal Climate Observatory - Pyramid" (NCO-P, 5079 m a.s.l., Nepal). This measurement station, part of UNEP-ABC and EV-K2-CNR SHARE projects, is not far from the Everest Base Camp and the observation here conducted can be considered representative for the South-Eastern slope of the Himalayan range. During the investigated period we detect more than 80 days/year as possibly affected by mineral dust transport. As deduced by the NCO-P measurements, these events significantly influenced the seasonal variation of coarse aerosol number concentration as well as the number and volumetric aerosol size distribution over South Himalayas. Due to the combination of the large-scale westerly circulation and the higher frequency of dust out-breaks, the majority of the identified events occurred during the pre-monsoon season. Although of lesser intensity and frequency, a significant amount of dust

  13. Lidar measurements of Raman scattering at ultraviolet wavelength from mineral dust over East Asia.

    PubMed

    Tatarov, Boyan; Müller, Detlef; Shin, Dong Ho; Shin, Sung Kyun; Mattis, Ina; Seifert, Patric; Noh, Young Min; Kim, Y J; Sugimoto, Nobuo

    2011-01-17

    We developed a novel measurement channel that utilizes Raman scattering from silicon dioxide (SiO2) quartz at an ultraviolet wavelength (361 nm). The excitation of the Raman signals is done at the primary wavelength of 355 nm emitted from a lidar instrument. In combination with Raman signals from scattering from nitrogen molecules, we may infer the mineral-quartz-related backscatter coefficient. This technique thus allows us to identify in a comparably direct way the mineral quartz content in mixed pollution plumes that consist, e.g., of a mix of desert dust and urban pollution. We tested the channel for the complex situation of East Asian pollution. We find good agreement of the inferred mineral-quartz-related backscatter coefficient to results obtained with another mineral quartz channel which was operated at 546 nm (primary emission wavelength at 532 nm), the functionality of which has already been shown for a lidar system in Tsukuba (Japan). The advantage of the novel channel is that it provides a better signal-to-noise ratio because of the shorter measurement wavelength.

  14. Emphysema and pulmonary impairment in coal miners: Quantitative relationship with dust exposure and cigarette smoking

    NASA Astrophysics Data System (ADS)

    Kuempel, E. D.; Vallyathan, V.; Green, F. H. Y.

    2009-02-01

    Coal miners have been shown to be at increased risk of developing chronic obstructive pulmonary diseases including emphysema. The objective of this study was to determine whether lifetime cumulative exposure to respirable coal mine dust is a significant predictor of developing emphysema at a clinically-relevant level of severity by the end of life, after controlling for cigarette smoking and other covariates. Clinically-relevant emphysema severity was determined from the association between individuals' lung function during life (forced expiratory volume in one second, FEV1, as a percentage of predicted normal values) and emphysema severity at autopsy (as the proportion of lung tissue affected). In a logistic regression model, cumulative exposure to respirable coal mine dust was a statistically significant predictor of developing clinically-relevant emphysema severity, among both ever-smokers and never-smokers. The odds ratio for developing emphysema associated with FEV1 <80% at the cohort mean cumulative coal dust exposure (87 mg/m3 x yr) was 2.30 (1.46-3.64, 95% confidence limits), and at the cohort mean cigarette smoking (among smokers: 42 pack-years) was 1.95 (1.39-2.79).

  15. Heterogeneous Reaction of SO2 on Authentic Mineral Dusts: Effects of Relative Humidity and H2O2

    NASA Astrophysics Data System (ADS)

    Huang, L.; Li, H.; Zhao, Y.; Chen, Z.

    2014-12-01

    Sulfur dioxide (SO2) is a significant precursor of sulfuric acid and sulfate aerosols in the atmosphere. Field and model studies have revealed that heterogeneous reaction on mineral dusts seem to be an important sink for SO2. However, available kinetic data about heterogeneous reaction of SO2 on authentic mineral dusts are scarce and are mainly limited at low humidity relative (RH). In addition, hydrogen peroxide (H2O2), which is the predominant oxidant of SO2 in the aqueous phase, may be able to promote the heterogeneous oxidation of SO2 on mineral dusts, but little is known about this role that H2O2 may play. In this study, we investigated the uptake kinetics of SO2 on authentic mineral dusts in the absence and presence of H2O2 at different RHs using a filter-based reactor. Three different authentic mineral dusts, i.e., Asian dust storm particles (ADS), Arizona test dust (ATD) and Tengger Desert sand (TDS), were used. The initial gas phase concentration of SO2 and H2O2 is about 5 ppbv and 0.8 ppbv, respectively, the typical concentration in the atmosphere. The values of uptake coefficients, γBET, on these particles are on the order of 10-5 under dry condition. Interestingly, with increasing RH, the γBET decreases on ADS particles, but increases on ATD and TDS particles. The difference in the mineralogy composition of these dust samples seems to rationalize the discrepancy in SO2 uptake. Furthermore, it is found that the presence of H2O2 increases the γBET by 45-90% on ADS, 45-150% on ATD and 40%-105% on TDS as RH increases 0 to 90%. One possible explanation for the observed behavior are that H2O2 can immediately react with SO2 on the surface of mineral dusts. Our results suggest that the role of heterogeneous reaction on mineral dusts as a sink of SO2 or a source of sulfate in the atmosphere may be underestimated due to the excluding of the enhancement effect of H2O2 in current atmospheric models.

  16. Heterogeneous Chemistry of Individual Mineral Dust Particles with Nitric Acid. A Combined CCSEM/EDX, ESEM AND ICP-MS Study

    SciTech Connect

    Laskin, Alexander; Wietsma, Thomas W.; Krueger, Brenda J.; Grassian, Vicki H.

    2005-05-26

    The heterogeneous chemistry of individual dust particles from four authentic dust samples with gas-phase nitric acid was investigated in this study. Morphology and compositional changes of individual particles as they react with nitric acid were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental Scanning Electron Microscopy (ESEM) was utilized to investigate the hygroscopic behavior of mineral dust particles reacted with nitric acid. Differences in the reactivity of mineral dust particles from these four different dust source regions with nitric acid were observed. Mineral dust from source regions containing high levels of calcium, namely China loess dust and Saudi coastal dust, were found to react to the greatest extent.

  17. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, A.; Shi, Z.

    2016-01-01

    Atmospheric deposition of anthropogenic soluble iron (Fe) to the ocean has been suggested to modulate primary ocean productivity and thus indirectly affect the climate. A key process contributing to anthropogenic sources of soluble Fe is associated with air pollution, which acidifies Fe-containing mineral aerosols during their transport and leads to Fe transformation from insoluble to soluble forms. However, there is large uncertainty in our estimate of this anthropogenic soluble Fe. In this study, for the first time, we interactively combined laboratory kinetic experiments with global aerosol modeling to more accurately quantify anthropogenic soluble Fe due to air pollution. Firstly, we determined Fe dissolution kinetics of African dust samples at acidic pH values with and without ionic species commonly found in aerosol water (i.e., sulfate and oxalate). Then, by using acidity as a master variable, we constructed a new empirical scheme for Fe release from mineral dust due to inorganic and organic anions in aerosol water. We implemented this new scheme and applied an updated mineralogical emission database in a global atmospheric chemistry transport model to estimate the atmospheric concentration and deposition flux of soluble Fe under preindustrial and modern conditions. Our improved model successfully captured the inverse relationship of Fe solubility and total Fe loading measured over the North Atlantic Ocean (i.e., 1-2 orders of magnitude lower Fe solubility in northern-African- than combustion-influenced aerosols). The model results show a positive relationship between Fe solubility and water-soluble organic carbon (WSOC)/Fe molar ratio, which is consistent with previous field measurements. We estimated that deposition of soluble Fe to the ocean increased from 0.05-0.07 Tg Fe yr-1 in the preindustrial era to 0.11-0.12 Tg Fe yr-1 in the present day, due to air pollution. Over the high-nitrate, low-chlorophyll (HNLC) regions of the ocean, the modeled Fe

  18. Proxies and measurement techniques for mineral dust in Antarctic ice cores.

    PubMed

    Ruth, Urs; Barbante, Carlo; Bigler, Matthias; Delmonte, Barbara; Fischer, Hubertus; Gabrielli, Paolo; Gaspari, Vania; Kaufmann, Patrik; Lambert, Fabrice; Maggi, Valter; Marino, Federica; Petit, Jean-Robert; Udisti, Roberto; Wagenbach, Dietmar; Wegner, Anna; Wolff, Eric W

    2008-08-01

    To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and water-insoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor approximately 100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is differentfor different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation.

  19. Chinese mineral dust and anthropogenic aerosol inter-continental transport: a Greenland perspective

    NASA Astrophysics Data System (ADS)

    Bory, A.; Abouchami, W.; Galer, S.; Svensson, A.; Biscaye, P.

    2012-04-01

    Impurities contained in snow and ice layers in Greenland provide a record of the history of atmospheric dustiness and pollution in the Northern Hemisphere. The source of the particles deposited onto the ice cap may be investigated using specific intrinsic tracers. Provenance discrimination may then provide valuable constraints for the validation of atmospheric transport models as well as for the monitoring of natural and anthropogenic aerosols emissions at a global scale. Clay mineralogy combined with the strontium and neodymium isotope composition of the insoluble particles extracted from recent snow deposits at NorthGRIP (75.1°N, 042.3°W), for instance, enabled us to demonstrate that the Taklimakan desert of North-western China was the main source of mineral dust reaching central Greenland at present [Bory et al., EPSL, 2002 ; GRL, 2003a]. Here we report the lead isotopic signature of these snow-pit samples, covering the 1989-1995 and 1998-2001 time periods. Unradiogenic lead isotopic composition of our Greenland samples, compared to Asian dust isotopic fingerprints, implies that most of the insoluble lead reaching the ice cap is of anthropogenic origin. Lead isotopes reveal likely contributions from European/Canadian and, to a lesser extent, US sources, as well as a marked overprinted signature typical of Chinese anthropogenic lead sources. The relative contribution of the latter appears to have been increasing steadily over the last decade of the 20th century. Quantitative estimates suggest that, in addition to providing most of the dust, China may have already become the most important supplier of anthropogenic lead deposited in Greenland by the turn of the 20th to the 21st century. The close timing between dust and anthropogenic particles deposition onto the ice cap provides new insights for our understanding of Chinese aerosols transport to Greenland.

  20. An evaluation of radiation and dust hazards at a mineral sand processing plant.

    PubMed

    Johnston, G

    1991-06-01

    This three-part article discusses the results of a 2-y study on radiation and dust hazards in a mineral sand processing plant involving: (1) evaluation of external gamma radiation levels and determination of isotopic composition of the different sand products; (2) evaluation of radiation carried in long-lived radioactive dust (LLRD) particles; (3) evaluation of Rn gas concentrations within the working environs of the plant. Gamma radiation levels had a mean value of approximately 40 nSv h-1, and monazite sand returned the highest activity concentrations of 0.16% and 3.4% for 238U and 232Th, respectively. Low volume gross respirable dust sampling revealed an average long-lived airborne alpha activity concentration of 0.07 +/- 0.02 Bq m-3 and an average dust mass concentration of 3.3 +/- 2 mg m-3. Gamma spectroscopy applied to high-volume air samples showed average airborne 232Th and 238U activities of 0.012 +/- 0.004 Bq m-3 and 0.005 +/- 0.002 Bq m-3, respectively, giving an airborne 232Th: 238U ratio of 2.4:1. Air sampling using a high volume, five-stage cascade impactor indicated an average activity median aerodynamic diameter (AMAD) of 3.2 microns with an associated average geometric standard deviation (GSD) of 2.8. Average radiation dose arising from the inhalation of LLRD was estimated to be 7 mSv per annum. CR-39 (polycarbonate plastic) nuclear track detectors indicated that Rn gas concentrations in the environs of the processing plant dry mill and main product warehouse ranged from 30 Bq m-3 to 220 Bq m-3, with an average value of 100 Bq m-3, which presents a possible inhaled dose from Rn daughters of 1.5 mSv y-1 (assuming an equilibrium ratio of 0.5).

  1. Iron oxide minerals in dust of the Red Dawn event in eastern Australia, September 2009

    NASA Astrophysics Data System (ADS)

    Reynolds, Richard L.; Cattle, Stephen R.; Moskowitz, Bruce M.; Goldstein, Harland L.; Yauk, Kimberly; Flagg, Cody B.; Berquó, Thelma S.; Kokaly, Raymond F.; Morman, Suzette; Breit, George N.

    2014-12-01

    Iron oxide minerals typically compose only a few weight percent of bulk atmospheric dust but are important for potential roles in forcing climate, affecting cloud properties, influencing rates of snow and ice melt, and fertilizing marine phytoplankton. Dust samples collected from locations across eastern Australia (Lake Cowal, Orange, Hornsby, and Sydney) following the spectacular "Red Dawn" dust storm on 23 September 2009 enabled study of the dust iron oxide assemblage using a combination of magnetic measurements, Mössbauer spectroscopy, reflectance spectroscopy, and scanning electron microscopy. Red Dawn was the worst dust storm to have hit the city of Sydney in more than 60 years, and it also deposited dust into the Tasman Sea and onto snow cover in New Zealand. Magnetization measurements from 20 to 400 K reveal that hematite, goethite, and trace amounts of magnetite are present in all samples. Magnetite concentrations (as much as 0.29 wt%) were much higher in eastern, urban sites than in western, agricultural sites in central New South Wales (0.01 wt%), strongly suggesting addition of magnetite from local urban sources. Variable temperature Mössbauer spectroscopy (300 and 4.2 K) indicates that goethite and hematite compose approximately 25-45% of the Fe-bearing phases in samples from the inland sites of Orange and Lake Cowal. Hematite was observed at both temperatures but goethite only at 4.2 K, thereby revealing the presence of nanogoethite (less than about 20 nm). Similarly, hematite particulate matter is very small (some of it d < 100 nm) on the basis of magnetic results and Mössbauer spectra. The degree to which ferric oxide in these samples might absorb solar radiation is estimated by comparing reflectance values with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance. Average visible reflectance and HIRM are correlated as a group (r2 = 0.24), indicating that Red Dawn ferric oxides have capacity to absorb

  2. Bone mineral alterations and Mg content in aging.

    PubMed

    Mongiorgi, R; Gnudi, S; Moroni, A; Bertocchi, G; Galliani, I; Benfenati, L

    1990-07-01

    The authors propose to determine whether the quantity of bone mass reduction linked to aging is accompanied by qualitative modifications of the mineral structure. To this end, 18 samples of cancellous bone from the femoral heads of two groups of patients (Groups A & B), were examined. Group A was made up of 8 old osteopenic patients suffering from fracture of the femur neck (age 62-84). Group B consisted of 10 young non-osteopenic subjects (age 34-53). Through chemical analysis a statistically significant percentage increase in Mg++ was noted in Group A and, by X-Ray diffraction, significant presence of beta-TCP. Mineral structure alterations occur in the process of aging of the skeletal tissue.

  3. Properties of M31 . I. Dust. Basic properties and a discussion about age-dependent dust heating

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Seitz, S.; Riffeser, A.; Hopp, U.; Lee, C.-H.; Schönrich, R.

    2009-11-01

    Aims: Observations acquired by the Spitzer Space Telescope and improvements to theoretical modeling of dust emission properties are used to discuss the distribution of dust and its characteristics in the closest neighbor spiral galaxy M31. These data are then used with GALEX FUV, NUV, and SDSS images to study the age dependence of the dust heating process. Methods: Spitzer IRAC/MIPS maps of M31 were matched together and compared to dust emission models allowing us to constrain the dust mass, the intensity of the mean radiation field, the abundance of polycyclic aromatic hydrocarbon (PAH) particles. The total infrared emission (TIR) was analyzed as a function of UV and optical colors and compared to predictions of models that consider age-dependent dust heating. Results: We demonstrate that cold-dust component emission dominates the infrared spectral energy distribution of M31. The mean intensity of the radiation field heating the dust is low (typically U < 2, where U = 1 is the value in the solar neighborhood). Because of a lack of submillimeter observations, the dust mass (M_dust) is only weakly constrained by the infrared spectrum, but we derived a lower limit of M_dust ≳ 1.1 × 107 M⊙ with a best-fit model value of M_dust = 7.6 × 107 M⊙, in good agreement with expectations from CO and HI measurements. Across the spiral-ring structure of M31, we show that a fraction >3% of the total dust mass is in PAHs. UV and optical colors are correlated with the total infrared to far ultraviolet (TIR/FUV) ratios in ~670 pc-sized regions over the disk of M31, although deviating from the relationship between infrared excess and ultraviolet spectral slope (referred as IRX-β relationship) for starburst galaxies. In particular, redder regions have lower values of the TIR/FUV ratio for a fixed color. Considering the predictions of models that account for the dust-heating age dependence, we found that in 83% of the regions analyzed across the 10 kpc ring, more than 50% of

  4. Modeling dust as component minerals in the Community Atmosphere Model: development of framework and impact on radiative forcing

    DOE PAGES

    Scanza, R. A.; Mahowald, N.; Ghan, S.; Zender, C. S.; Kok, J. F.; Liu, X.; Zhang, Y.; Albani, S.

    2015-01-15

    The mineralogy of desert dust is important due to its effect on radiation, clouds and biogeochemical cycling of trace nutrients. This study presents the simulation of dust radiative forcing as a function of both mineral composition and size at the global scale, using mineral soil maps for estimating emissions. Externally mixed mineral aerosols in the bulk aerosol module in the Community Atmosphere Model version 4 (CAM4) and internally mixed mineral aerosols in the modal aerosol module in the Community Atmosphere Model version 5.1 (CAM5) embedded in the Community Earth System Model version 1.0.5 (CESM) are speciated into common mineral componentsmore » in place of total dust. The simulations with mineralogy are compared to available observations of mineral atmospheric distribution and deposition along with observations of clear-sky radiative forcing efficiency. Based on these simulations, we estimate the all-sky direct radiative forcing at the top of the atmosphere as + 0.05 Wm−2 for both CAM4 and CAM5 simulations with mineralogy. We compare this to the radiative forcing from simulations of dust in release versions of CAM4 and CAM5 (+0.08 and +0.17 Wm−2) and of dust with optimized optical properties, wet scavenging and particle size distribution in CAM4 and CAM5, −0.05 and −0.17 Wm−2, respectively. The ability to correctly include the mineralogy of dust in climate models is hindered by its spatial and temporal variability as well as insufficient global in situ observations, incomplete and uncertain source mineralogies and the uncertainties associated with data retrieved from remote sensing methods.« less

  5. Modeling dust as component minerals in the Community Atmosphere Model: development of framework and impact on radiative forcing

    DOE PAGES

    Scanza, R. A.; Mahowald, N.; Ghan, S.; Zender, C. S.; Kok, J. F.; Liu, X.; Zhang, Y.

    2014-07-02

    The mineralogy of desert dust is important due to its effect on radiation, clouds and biogeochemical cycling of trace nutrients. This study presents the simulation of dust radiative forcing as a function of both mineral composition and size at the global scale using mineral soil maps for estimating emissions. Externally mixed mineral aerosols in the bulk aerosol module in the Community Atmosphere Model version 4 (CAM4) and internally mixed mineral aerosols in the modal aerosol module in the Community Atmosphere Model version 5.1 (CAM5) embedded in the Community Earth System Model version 1.0.5 (CESM) are speciated into common mineral componentsmore » in place of total dust. The simulations with mineralogy are compared to available observations of mineral atmospheric distribution and deposition along with observations of clear-sky radiative forcing efficiency. Based on these simulations, we estimate the all-sky direct radiative forcing at the top of the atmosphere as +0.05 W m−2 for both CAM4 and CAM5 simulations with mineralogy and compare this both with simulations of dust in release versions of CAM4 and CAM5 (+0.08 and +0.17 W m−2) and of dust with optimized optical properties, wet scavenging and particle size distribution in CAM4 and CAM5, −0.05 and −0.17 W m−2, respectively. The ability to correctly include the mineralogy of dust in climate models is hindered by its spatial and temporal variability as well as insufficient global in-situ observations, incomplete and uncertain source mineralogies and the uncertainties associated with data retrieved from remote sensing methods.« less

  6. Global trends in mineral dust aerosol: determining causes and attributing uncertainty with the GEOS-Chem model

    NASA Astrophysics Data System (ADS)

    Ridley, D. A.; Heald, C. L.; Prospero, J. M.

    2014-12-01

    Mineral dust aerosol constitutes a large fraction of the total aerosol burden, which presents health risks, alters atmospheric chemistry, and strongly perturbs the radiative balance over large regions. Therefore, it is imperative that we understand what controls the observed trends and changes in variability of dust emissions. Recently, we have shown that the observed reduction in African dust loading over the Atlantic in recent decades is likely driven by large-scale wind changes over source regions rather than changes in vegetation cover. Using an updated dust emission scheme and information from high resolution (0.25 degree) simulations from the NASA GEOS model, we attribute the uncertainty in modeled dust AOD and expand the analysis to other regions of the world, including Asia and the Middle East.

  7. Effect of mineral dust on ocean color retrievals from space: A radiative transfer simulation study

    NASA Astrophysics Data System (ADS)

    Ahmad, Z.; Franz, B. A.

    2014-12-01

    Mineral aerosols (dust) are one of the major components of all aerosols found in the Earth's atmosphere. They are mainly soil particles that originate from arid and semiarid regions of the world that can be carried by winds for thousands of kilometers. They are a major impediment in the remote sensing of the ocean color (spectral water-leaving reflectance), because they absorb solar radiation in the UV and visible part of the spectrum and their micro-physical and optical properties are highly variable. Further, there are no reliable working algorithms to detect their presence from spaceborne ocean color observations alone, when they are present in small amount (optical thickness < 0.2). In this paper we examine effect of mineral dust on ocean color retrieval from space. We use Ahmad-Fraser's vector radiative transfer (RT) code (v3.0) for ocean-atmosphere system to simulate the pseudo observations (top of atmosphere radiance) for models containing different types of aerosols (absorbing and non-absorbing) in the atmosphere. We consider the mineral aerosols as consisting of an external mixture of illite, kaolinite, montmorillonite, quartz, and calcite with a small amount of hematite (as an internal mixture), which provide the spectral dependence of single scattering albedo consistent with the values reported in the literature. We also vary the aerosol layer height in the atmosphere and amount of chlorophyll in the ocean. The simulated pseudo observations were processed through standard NASA algorithms to determine the ocean color (spectral water-leaving reflectance) and derived chlorophyll in the ocean. Results of the RT simulation study for different Sun-satellite viewing geometry, aerosol layer height and chlorophyll amount in the ocean is presented.

  8. Characterisation of mineral dust emission in the Middle EAST using the Spinning Enhanced Visible and Infrared Imager (SEVIRI)

    NASA Astrophysics Data System (ADS)

    Hennen, M.; Shahgedanova, M.; White, K.

    2015-12-01

    Using the Spinning Enhanced Visual and InfraRed Imager (SEVIRI) on-board Meteosat's second generation satellite (MSG), mineral dust emissions from the Middle East were observed at a high temporal and spatial resolution between the years 2006 and 2013. This research provides a subjective derivation of mineral dust source locations in the Middle East using the thermal infrared Dust RGB product. Focusing on the brightness temperature difference around 10.8 µm channel and their spectral contrast with clear sky conditions, the Dust RGB product has been recognised as a major asset in detecting dust. While the product has already been used to map dust emissions in Sahara and south Africa, this research is the first to map dust emissions in the Middle East using SEVIRI, one of the dustiest regions in the world second only to the Sahara Desert. For every dust storm activation within the Middle East, the point of first emission is derived from visual inspection of each 15 minute image, these points were then recorded in a dust source climatology (DSC) database, along with time and direction of dust movement. To take account of potential errors inherent in this subjective detection method, a degree of confidence is associated with each data point with relevance to time of day (which has a strong effect on ability to detect dust in these products) and weather conditions, in particular presence of clouds. These results are compared with an automated retrieval using Aerosol Optical Depth (AOD) measurements form the Moderate Resolution Image Spectrometer (MODIS); which, due to its sun-synchronous orbit allows a measurement of dust in the atmosphere once a day. Differences in the spatial distribution of SEVIRI dust sources and MODIS inferred dust source regions can be explained by inherent transport bias in the latter's low sampling rate and prevailing wind conditions. This database will provide an important tool in further understanding dust emission processes in the region

  9. Global distribution of mineral dust and its impact on radiative fluxes as simulated by WRF-Chem

    NASA Astrophysics Data System (ADS)

    Alizadeh-Choobari, Omid; Sturman, Andrew; Zawar-Reza, Peyman

    2015-12-01

    Dust aerosols make a considerable contribution to the climate system and atmospheric hydrological cycle through their radiative and ice nuclei effects. This underlines the need for investigating the sources of dust aerosols, their transport pathways, and radiative forcing. Seasonal distribution of mineral dust around the globe and its impact on radiation fluxes is estimated using two simulations: a model setup that did not include dust aerosols; and an interactive experiment that included dust aerosols and their feedback to the atmosphere. Simulations were performed by the Weather Research and Forecasting with Chemistry (WRF-Chem) model for a 1-year period. The global annual mean dust optical depth (DOD) at 0.55 \\upmum is estimated to be 0.057, with a spring peak value of 0.081 and an autumn minimum value of 0.039. Seasonal variation of atmospheric dust loading is shown to be associated with similar significant variation in shortwave and longwave direct radiation perturbation by dust, both at the surface and top of the atmosphere (TOA). The presence of mineral dust in the interactive simulation is estimated to exert a maximum net direct radiation perturbation in summer with values of -2.85 and -1.63 W m^{-2} in clear-sky conditions at the surface and TOA, respectively. It also exerts a global annual net direct radiation perturbation of -1.86 and -1.09 W m^{-2} at the surface and TOA, respectively. The surface cooling is attributed to the extinction of incoming solar radiation by dust aerosols, while negative perturbation at the TOA (which demonstrates cooling of the Earth-atmosphere system) is predominantly attributed to an increase in outgoing shortwave radiation.

  10. A global satellite view of the seasonal distribution of mineral dust and its correlation with atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Alizadeh-Choobari, O.; Sturman, A.; Zawar-Reza, P.

    2014-12-01

    Aerosols make a considerable contribution to the climate system through their radiative and cloud condensation nuclei effects, which underlines the need for understanding the origin of aerosols and their transport pathways. Seasonal distribution of mineral dust around the globe and its correlation with atmospheric circulation is investigated using satellite data, and meteorological data from ECMWF. The most important sources of dust are located in North Africa, the Middle East and Southwest Asia with an observed summer maximum, and East Asia with a spring peak. Maximum dust activity over North Africa and the Middle East in summer is attributed to dry convection associated with the summertime low-pressure system, while unstable weather and dry conditions are responsible for the spring peak in dust emission in East Asia. Intercontinental transport of mineral dust by atmospheric circulation has been observed, including trans-Atlantic transport of North African dust, trans-Pacific transport of Asian dust, and transport of dust from the Middle East across the Indian Ocean. The extent of African dust over the Atlantic Ocean and its latitudinal variation with season is related to the large-scale atmospheric circulation, including seasonal changes in the position of the intertropical convergence zone (ITCZ) and variation of wind patterns. North African aerosols extend over longer distances across the North Atlantic in summer because of greater dust emission, an intensified easterly low level jet (LLJ) and strengthening of the Azores-Bermuda anticyclonic circulation. Transport of East Asian aerosol is facilitated by the existence of a LLJ that extends from East Asia to the west coast of North America.

  11. Vertical Structure of Aerosols and Mineral Dust Transport Over the Bay of Bengal Using Multi-Satellite Observations.

    NASA Astrophysics Data System (ADS)

    Naduparambil Bharathan, L.

    2015-12-01

    Bay-of-Bengal (BoB), a small oceanic region Eat to Indian land mass, surrounded by heavily inhabited land masses, experiences different types of air-masses in different seasons of contrasting wind patterns, which makes it a region of large heterogeneity in the context of regional climate forcing due to atmospheric aerosols. Heterogeneity of aerosol system over the Bay of Bengal is mainly determined by three distinct source regions, which are east coast of India/central India, China/east Asia and Arabian region. Continental aerosols transported through higher elevations over BoB lead to significant impacts in regional climate by modifying the vertical thermal structure of the atmosphere and associated circulation dynamics. The study aims at a comprehensive understanding on the spatial and temporal heterogeneity of elevated aerosol over the BoB using the observations of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Being capable of short wave scattering and long wave absorption, mineral dust aerosols can affects the energetics of the atmosphere over any region.Owing to its influence on Indian monsoon rainfall and regional climate, the study aims to comprehend on the spatial and seasonal variation of mineral dust transport over the Bay of Bengal. vertical distribution of the dust extinction coefficient over the Bay of Bengal for all seasons, is derived, using a dust separation scheme that uses the depolarization measurements, a priori information on lidar ratio of dust, depolarization ratio of dust and that of non-dust aerosols. Being highly non-spherical, mineral dust significantly depolarize the radiation and possess distinct range of depolarization ratio. This property of dust is made use to identify and quantify dust over the study region. Seasonal variation of dust fraction over the Bay of Bengal is estimated seperately from CALIPSO back scattering coefficients

  12. Contact freezing induced by biological (Snomax) and mineral dust (K-feldspar) particles

    NASA Astrophysics Data System (ADS)

    Hoffmann, N.; Schäfer, M.; Duft, D.; Kiselev, A. A.; Leisner, T.

    2013-12-01

    The contact freezing of supercooled cloud droplets is one of the potentially important and the least investigated heterogeneous mechanism of ice formation in tropospheric clouds [1]. On the time scales of cloud lifetime the freezing of supercooled water droplets via contact mechanism may occur at higher temperature compared to the same IN immersed in the droplet. In our experiment we study single water droplets freely levitated in an Electrodynamic Balance [2]. We have shown previously that the rate of freezing at given temperature is governed only by the rate of droplet -particle collision and by the properties of the contact ice nuclei [2, 3]. Recently, we have extended our experiments to feldspar, being the most abundant component of the atmospheric mineral dust particles, and Snomax, as a proxy for atmospheric biological Ice Nuclei (IN). In this contribution we show that both IN exhibits the same temperature, size and material dependency observed previously in immersion mode [4, 5]. Based on these results, we limit the number of mechanisms that could be responsible for the enhancement of contact nucleation of ice in supercooled water. [1] - Ladino, L. A., Stetzer, O., and Lohmann, U.: Contact freezing: a review, Atmos. Chem. Phys. Discuss., 13, 7811-7869, doi:10.5194/acpd-13-7811-2013, 2013. [2] - Hoffmann, N., Kiselev, A., Rzesanke, D., Duft, D., and Leisner, T.: Experimental quantification of contact freezing in an electrodynamic balance, Atmos. Meas. Tech. Discuss., 6, 3407-3437, doi:10.5194/amtd-6-3407-2013, 2013. [3] - Hoffmann, N., Duft, D., Kiselev, A., and Leisner, T.: Contact freezing efficiency of mineral dust aerosols studied in an electrodynamic balance: quantitative size and temperature dependence for illite particles, Faraday Discuss., doi: 10.1039/C3FD00033H, 2013. [4] - Atkinson, James D., Murray, Benjamin J., Woodhouse, Matthew T., Whale, Thomas F., Baustian, Kelly J., Carslaw, Kenneth S., Dobbie, Steven, O'Sullivan, Daniel, and Malkin, Tamsin

  13. Characterization of minerals in air dust particles in the state of Tamilnadu, India through FTIR, XRD and SEM analyses

    NASA Astrophysics Data System (ADS)

    Senthil Kumar, R.; Rajkumar, P.

    2014-11-01

    The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR, XRD absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively. The shape and size of the particulates are studied with SEM analysis.

  14. Quaternary dust sources on the Chinese Loess Plateau: a view from single zircon grains, heavy minerals and quartz luminescence

    NASA Astrophysics Data System (ADS)

    Stevens, T.; Carter, A.; Vermeesch, P.; Bird, A.; Rittner, M.; Lu, H.; Andò, S.; Garzanti, E.; Nie, J.; Adamiec, G.; Zeng, L.; Zhang, H.; Xu, Z.

    2013-12-01

    The origin of loess deposits on the Chinese Loess Plateau (CLP), one of the most valuable Cenozoic climate archives on land, is the subject of considerable debate. A large number of sources have been proposed for the vast quantity of dust that forms the up to 400 m thick loess sequences that cover the c. 640,000 km2 the CLP, including deserts, alluvial fans and mountain regions. There is also debate over whether sources shift across the CLP, within loess units, between units and across the Quaternary/Pliocene boundary. Furthermore, the role of river systems in sediment supply to the CLP has not previously been substantively addressed. Geochemical analysis of bulk sediment from loess is limited by mixing of different source influences and so here we apply a variety of techniques to Quaternary sequences on the CLP. We use single-grain based techniques on zircons and heavy mineral analyses in an attempt to discriminate between potential multiple sources and to test the influence of proximal deserts and major rivers on CLP dust. In addition, we utilise information from detailed optically stimulated luminescence dating of quartz from loess to identify rapid shifts in source region on the CLP. Provenance signatures from samples from the eastern Mu Us and the Tengger deserts can be explained by local sources and recycling of the underlying Cretaceous rock. However, the western Mu Us desert as well as Quaternary loess shows different zircon U-Pb age spectra and heavy mineral distributions, indicative of strong influence from northeastern Tibet. Further, samples from the Yellow River are close to identical to these western Mu Us samples and crucially, also to Quaternary samples from the Loess Plateau. This suggests that the Tibetan-derived sediments are unlikely to have been transported from Tibet by wind, but rather may have been delivered by the Yellow River. This provides the first evidence of a possible genetic link between the Yellow River and the CLP. However, there

  15. Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2014-09-01

    Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

  16. Mineral dust and NOx promote the conversion of SO2 to sulfate in heavy pollution days

    PubMed Central

    He, Hong; Wang, Yuesi; Ma, Qingxin; Ma, Jinzhu; Chu, Biwu; Ji, Dongsheng; Tang, Guiqian; Liu, Chang; Zhang, Hongxing; Hao, Jiming

    2014-01-01

    Haze in China has been increasing in frequency of occurrence as well as the area of the affected region. Here, we report on a new mechanism of haze formation, in which coexistence with NOx can reduce the environmental capacity for SO2, leading to rapid conversion of SO2 to sulfate because NO2 and SO2 have a synergistic effect when they react on the surface of mineral dust. Monitoring data from five severe haze episodes in January of 2013 in the Beijing-Tianjin-Hebei regions agreed very well with the laboratory simulation. The combined air pollution of motor vehicle exhaust and coal-fired flue gases greatly reduced the atmospheric environmental capacity for SO2, and the formation of sulfate was found to be a main reason for the growth of fine particles, which led to the occurrence of haze. These results indicate that the impact of motor vehicle exhaust on the atmospheric environment might be underestimated. PMID:24566871

  17. Pulmonary mineral dust. A study of ninety patients by electron microscopy, electron microanalysis, and electron microdiffraction.

    PubMed Central

    Berry, J. P.; Henoc, P.; Galle, P.; Pariente, R.

    1976-01-01

    The results of a study of 90 patients are presented. Intrapulmonary mineral deposits were characterized by electron diffraction and electron probe microanalysis. Using this method, pneumoconioses may be distinguidhed from other pneumopathies. In cases of pneumoconiosis, there exists a specific relationship between the etiology of the dust exposure and the crystallographic characteristics of the intrapulmonary deposits. The nature of the deposits may be indicative of a specific type of pneumoconiosis. This method is particularly useful in differentiating between asbestos bodies and ferruginous bodies. The value of the method in general and its importance in the study of pneumoconiosis are discussed. Images Figure 4 Figure 13 Figure 5 Figure 14 Figure 6 Figure 15 Figure 7 Figure 16 Figure 8 Figure 17 Figure 1 Figure 9 Figure 10 Figure 2 Figure 11 Figure 3 Figure 12 PMID:937507

  18. The immersion freezing behavior of mixtures of mineral dust and biological substances

    NASA Astrophysics Data System (ADS)

    Augustin, Stefanie; Schneider, Johannes; Schmidt, Susan; Niedermeier, Dennis; Ebert, Martin; Voigtländer, Jens; Rösch, Michael; Stratmann, Frank; Wex, Heike

    2014-05-01

    Biological particles such as bacteria or pollen are known to be efficient ice nuclei. It is also known that ice nucleating active (INA) macromolecules, i.e. protein complexes in the case of bacteria (e.g. Wolber et al., 1986), and most likely polysaccharides in the case of pollen (Pummer et al., 2012) are responsible for the freezing. Very recently it was suggested that these INA macromolecules maintain their nucleating ability even when they are separated from their original carriers (Hartmann et al., 2013; Augustin et al., 2013). This opens the possibility of accumulation of such INA macromolecules in e.g. soils and the resulting particles could be an internal mixture of mineral dust and INA macromolecules. If such biological IN containing soil particles are then dispersed into the atmosphere due to e.g. wind erosion or agricultural processes they could induce ice nucleation at temperatures higher than -20°C. To explore this hypothesis, we performed a measurement campaign within the research unit INUIT, where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INA macromolecules. Specifically, we mixed pure mineral dust (illite) with INA biological material (SNOMAX and birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). To characterize the mixing state of the produced aerosol we used single mass spectrometry as well as electron microscopy. We found that internally mixed particles which containing ice active biological material show the same ice nucleation behavior as the purely biological particles. That shows that INA macromolecules which are located on a mineral dust particle dominate the freezing process. Acknowledgement: Part of this work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. Augustin, S., Hartmann, S., Pummer, B., Grothe, H

  19. Analysis and differentiation of mineral dust by single particle laser mass spectrometry

    SciTech Connect

    Gallavardin, S. J.; Lohmann, U.; Cziczo, Daniel J.

    2008-05-09

    Abstract This study evaluates the potential of single particle laser desorption/ionization mass spectrometry for the analysis of atmospherically relevant mineral dusts. Samples of hematite, goethite, calcium carbonate, calcium sulfate, silica, quartz, montmorrillonite, kaolinite, illite, hectorite, wollastonite and nephelinsyenit were investigated in positive and negative ion mode with a monopolar time-of-flight mass spectrometer where the desorption/ionization step was performed with a 193 nm excimer laser (~109 W/cm2). Particle size ranged from 500 nm to 3 μm. Positive mass spectra mainly provide elemental composition whereas negative ion spectra provide information on element speciation and of a structural nature. The iron oxide, calcium-rich and aluminosilicate nature of particles is established in positive ion mode. The differentiation of calcium materials strongly relies on the calcium counter-ions in negative mass spectra. Aluminosilicates can be differentiated in both positive and negative ion mode using the relative abundance of various aluminum and silicon ions.

  20. Seasonal variations of snow chemistry and mineral dust in the snow pit at GV7, Antarctica

    NASA Astrophysics Data System (ADS)

    Kang, Jung-Ho; Hwang, Heejin; Han, Yongchoul; Hong, Sang Bum; Lee, Khanghyun; Do Hur, Soon; Frezzotti, Massimo; Narcisi, Biancamaria

    2015-04-01

    We conducted the scientific ice coring project led by PNRA and KOPRI during the 2013/2014 Italian-Korean Antarctic Expedition in the framework of International Partnerships in Ice Core Science (IPICS) to understand the climatic variability in the last 2000 years. In the part of project, we collected a 3.0 m-depth snow pit at the site of GV7 (S 70° 41'17.1", E 158° 51'48.9", 1950 m a.s.l.), Antarctica. Here, we present the results obtained from the analysis of the water isotope compositions, the major ion concentrations, and the mineral dust concentrations from the snow pit. Snow densities and temperatures also measured in the field. At KOPRI, the samples were melted, then the stable water isotopes, major ions, and particle size distribution were analyzed with the cavity ring-down spectrometers (L1102-i, Piccaro), ion chromatography (ICS-2100, Thermo), and coulter counter (Multisizer 3, Beckman Coulter), respectively. The δ18O varies between -38.3 and -24.1o with a mean value of -31.0o. The δD ranges between -331 and -186o with a mean value of -243o. Among the ion concentrations (Na+, Ca2+, Mg2+, Cl-, SO42-, CH3SO3-(MSA)) from the snow pit, MSA concentrations show a clear seasonal variation. The mineral dust in the pit characterized with the differences of the concentration and the particle size distribution by the seasonality. These data allow us to assume about 4.5 years of snow deposition covered from 2009 to 2013 by these oscillations of the isotopes and geochemical characteristics.

  1. Knudsen cell and smog chamber study of the heterogeneous uptake of sulfur dioxide on Chinese mineral dust.

    PubMed

    Zhou, Li; Wang, Weigang; Gai, Yanbo; Ge, Maofa

    2014-12-01

    The heterogeneous uptake processes of sulfur dioxide on two types of Chinese mineral dust (Inner Mongolia desert dust and Xinjiang sierozem) were investigated using both Knudsen cell and smog chamber system. The temperature dependence of the uptake coefficients was studied over a range from 253 to 313 K using the Knudsen cell reactor, the initial uptake coefficients decreased with the increasing of temperature for these two mineral dust samples, whereas the steady state uptake coefficients of the Xinjiang sierozem increased with the temperature increasing, and these temperature dependence functions were obtained for the first time. In the smog chamber experiments at room temperature, the steady state uptake coefficients of SO2 decreased evidently with the increasing of sulfur dioxide initial concentration from 1.72 × 10¹² to 6.15 × 10¹² mol/cm³. Humid air had effect on the steady state uptake coefficients of SO₂onto Inner Mongolia desert dust. Consequences about the understanding of the uptake processes onto mineral dust samples and the environmental implication were also discussed.

  2. Knudsen cell and smog chamber study of the heterogeneous uptake of sulfur dioxide on Chinese mineral dust.

    PubMed

    Zhou, Li; Wang, Weigang; Gai, Yanbo; Ge, Maofa

    2014-12-01

    The heterogeneous uptake processes of sulfur dioxide on two types of Chinese mineral dust (Inner Mongolia desert dust and Xinjiang sierozem) were investigated using both Knudsen cell and smog chamber system. The temperature dependence of the uptake coefficients was studied over a range from 253 to 313 K using the Knudsen cell reactor, the initial uptake coefficients decreased with the increasing of temperature for these two mineral dust samples, whereas the steady state uptake coefficients of the Xinjiang sierozem increased with the temperature increasing, and these temperature dependence functions were obtained for the first time. In the smog chamber experiments at room temperature, the steady state uptake coefficients of SO2 decreased evidently with the increasing of sulfur dioxide initial concentration from 1.72 × 10¹² to 6.15 × 10¹² mol/cm³. Humid air had effect on the steady state uptake coefficients of SO₂onto Inner Mongolia desert dust. Consequences about the understanding of the uptake processes onto mineral dust samples and the environmental implication were also discussed. PMID:25499490

  3. Age Impacts Pulmonary Inflammation and Systemic Bone Response to Inhaled Organic Dust Exposure.

    PubMed

    Poole, Jill A; Romberger, Debra J; Wyatt, Todd A; Staab, Elizabeth; VanDeGraaff, Joel; Thiele, Geoffrey M; Dusad, Anand; Klassen, Lynell W; Duryee, Michael J; Mikuls, Ted R; West, William W; Wang, Dong; Bailey, Kristina L

    2015-01-01

    Agricultural workers have high rates of airway and skeletal health disease. Studies recently demonstrated that inhaled agricultural organic dust extract (ODE)-induced airway injury is associated with bone deterioration in an animal model. However, the effect of age in governing these responses to organic dusts is unclear, but might be important in future approaches. Young (7-9 wk) and older (12-14,o) male C57BL/6 mice received intranasal (i.n.) inhalation exposure to ODE from swine confinement facilities once or daily for 3 wk. Acute ODE-induced neutrophil influx and cytokine and chemokine (tumor necrosis factor [TNF]-α, interleukin [IL]-6, keratinocyte chemoattractant [CXCL1], macrophage inflammatory protein-2 [CXCL2]) airway production were reduced in older compared to young mice. Repetitive ODE treatment, however, increased lymphocyte recruitment and alveolar compartment histopathologic inflammatory changes in older mice. Whole lung cell infiltrate analysis revealed that young, but not older, mice repetitively treated with ODE demonstrated an elevated CD4:CD8 lymphocyte response. Acute inhalant ODE exposure resulted in a 4-fold and 1.5-fold rise in blood neutrophils in young and older mice, respectively. Serum IL-6 and CXCL1 levels were elevated in young and older mice i.n. exposed once to ODE, with increased CXCL1 levels in younger compared to older mice. Although older mice displayed reduced bone measurements compared to younger mice, younger rodents demonstrated ODE-induced decrease in bone mineral density, bone volume, and bone microarchitecture quality as determined by computed tomography (CT) analysis. Collectively, age impacts the airway injury and systemic inflammatory and bone loss response to inhalant ODE, suggesting an altered and enhanced immunologic response in younger as compared to older counterparts.

  4. Modelling direct radiative effect of mineral dust with the NMMB/BSC-CTM for dust outbreak events over the Mediterranean in summer 2012

    NASA Astrophysics Data System (ADS)

    Obiso, Vincezo; Jorba, Oriol; Basart, Sara; Baldasano, Jose M.; Nabat, Pierre

    2014-05-01

    Aerosols interact with the atmospheric system scattering and absorbing solar radiation, with a significant impact on atmospheric energy and hydrologic processes. Radiative forcing associated with these perturbations affects climate and meteorology. In this contribution, we analyse model results of the Direct Radiative Effect (DRE) of mineral dust over the western-Mediterranean during summer 2012. For that, the NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) is applied on a regional domain at 0.1º horizontal resolution. The NMMB/BSC-CTM is a new on-line chemical weather prediction system coupling atmospheric and chemistry processes. In the radiation module of the model mineral dust is treated as a radiatively active substance interacting both short and longwave radiation. The impact of the mineral dust outbreaks on meteorology is discussed by comparing model forecasts with atmospheric analysis and meteorological observations. The analysis focuses in the vertical structure of the atmosphere and the resulting surface meteorological conditions. The authors acknowledge the support from the grant SEV-2011-00067 of Severo Ochoa Program, awarded by the Spanish Government.

  5. Mineral carbonation for carbon sequestration in cement kiln dust from waste piles.

    PubMed

    Huntzinger, Deborah N; Gierke, John S; Sutter, Lawrence L; Kawatra, S Komar; Eisele, Timothy C

    2009-08-30

    Alkaline earth metals, such as calcium and magnesium oxides, readily react with carbon dioxide (CO(2)) to produce stable carbonate minerals. Carbon sequestration through the formation of carbonate minerals is a potential means to reduce CO(2) emissions. Calcium-rich, industrial solid wastes and residues provide a potential source of highly reactive oxides, without the need for pre-processing. This paper presents the first study examining the feasibility of carbon sequestration in cement kiln dust (CKD), a byproduct generated during the manufacturing of cement. A series of column experiments were conducted on segments of intact core taken from landfilled CKD. Based on stoichiometry and measured consumption of CO(2) during the experiments, degrees of carbonation greater than 70% of the material's potential theoretical extent were achieved under ambient temperature and pressure conditions. The overall extent of carbonation/sequestration was greater in columns with lower water contents. The major sequestration product appears to be calcite; however, more detailed material characterization is need on pre- and post-carbonated samples to better elucidate carbonation pathways and products.

  6. Mineral dust events over the Mediterranean: Multi-platform characterization and comparison with GEOS-Chem simulation

    NASA Astrophysics Data System (ADS)

    Bartlett, K. S.; Luo, G.; Yu, F.; Aerosol Microphysics Research Group

    2011-12-01

    Kevin S. Bartlett, Gan Luo, and Fangqun Yu Atmospheric Sciences Research Center, State University of New York, 251 Fuller Road, Albany, New York 12203, USA Abstract. The Mediterranean Basin (MB) has a population of 210 million with approximately 50% living within the eastern half of the MB where seasonal lows tracking southeastward across Italy transport climate impacting, visibility and air quality reducing mineral dust from North African deserts. Located 1000 km NE of African dust and 400 km SE of Greek population centers, Crete is uniquely located at a crossroads of the seasonal storm track and a mineral dust pathway recording some of the highest average AODs within the region, and is well instrumented to observe this trend. Investigating dust transport using NCEP reanalysis data, surface based METAR, AERONET and SMPS as well as space based MODIS, MISR and CALIPSO observations coupled with nested GEOS-Chem-APM simulations, this study exploits sensor strengths while noting weaknesses to characterize seasonal trends and individual dust events. To verify seasonal trends, METAR, AERONET and NCEP data were collected over Crete from 2003-2010. This 8 year period showed that the majority of large aerosol events occurred during late winter and early spring during passage of transitional low pressure systems. During 2009, newly released, SMPS particle size distribution measurements were acquired from Finokalia. These in situ measurements coupled with the observation collective were key to confirming dust events and for comparing the nested GEOS-Chem's particle size distribution and AOD simulations, which showed some skill capturing dust events as well as the seasonal dust peaks early in the year. In this study we exploited the strengths of the observation collective and model runs to prove seasonal North African dust transport across Crete. We also noted the limitations of surface based: point observations, limited to localized conditions of transport and fallout, where

  7. Variations on morphology and elemental composition of mineral dust particles from local, regional, and long-range transport meteorological scenarios

    NASA Astrophysics Data System (ADS)

    Coz, Esther; Gómez-Moreno, Francisco J.; Casuccio, Gary S.; ArtíñAno, BegoñA.

    2010-06-01

    Mineral dust is the second major source of PM10 in Madrid, reaching up to 80% of the PM10 mass during certain long-range dust transport events. Three different types of scenarios have been found to be associated with the high particle concentration episodes in the city: local anthropogenic, regional recirculation, and African dust transport processes. The present study focuses on the characterization of the individual mineral dust particles related to some chemical and morphological features during these three types of episodes, with special attention to local and regional episodes. To achieve this purpose, four different samples were selectively collected during the 2004-2005 period campaigns, one corresponding to each type of scenario and other sample from an Atlantic ventilated one. Meteorological situation, dust source identification, impact on ambient concentrations, size range distribution, and particle individual analysis have been characterized for each of them. Elemental composition and morphology of more than 30,000 mineral particles were analyzed by computer-controlled scanning electron microscopy. Particles were grouped into clusters based on their elemental composition, and the aspect ratio (AR) of each cluster or category was compared for each type of episode. The AR was related to the mineralogical crystal structure of each chemical cluster. The dates chosen for microscopy analysis were in good agreement in size distribution and chemical composition with the average of the dates in the entire campaign and with those from previous campaigns. Major differences between local/regional and long-range transported mineral dust were found in the relative abundance between carbonates and silicates, with much higher abundance of calcium carbonates in the first ones. These differences between silicate and carbonate contents were consistent with the results found in previous campaigns and were directly related to the composition of the parent topsoil by studying

  8. Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

    DOE PAGES

    DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; et al

    2014-06-27

    Data from both laboratory studies and atmospheric measurements are used to develop a simple parametric description for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken to approximate the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developedmore » follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A correction factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this correction factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization to the immersion

  9. Integrating laboratory and field data to quantify the immersion freezing ice nucleation activity of mineral dust particles

    DOE PAGES

    DeMott, P. J.; Prenni, A. J.; McMeeking, G. R.; Sullivan, R. C.; Petters, M. D.; Tobo, Y.; Niemand, M.; Möhler, O.; Snider, J. R.; Wang, Z.; et al

    2015-01-13

    Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterizationmore » developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration

  10. Wettability shifts caused by CO2 aging on mineral surfaces

    NASA Astrophysics Data System (ADS)

    Liang, B.; Clarens, A. F.

    2015-12-01

    Interfacial forces at the CO2/brine/mineral ternary interface have a well-established impact on multiphase flow properties through porous media. In the context of geologic carbon sequestration, this wettability will impact capillary pressure, residual trapping, and a variety of other key parameters of interest. While the wettability of CO2 on pure mineral and real rock sample have been studied a great deal over the past few year, very little is known about how the wettability of these rocks could change over long time horizons as CO2 interacts with species in the brine and on the mineral surface. In this work we sought to explore the role that dilute inorganic and organic species that are likely to exist in connate brines might have on a suite of mineral species. High-pressure contact angle experiments were carried out on a suite of polished mineral surfaces. Both static captive bubble and advancing/receding contact angle measurements were carried out. The effect of ionic strength, and in particular the valence of the dominant ions in the brine are found to have an important impact on the wettability which cannot be explained solely based on the shifts in the interfacial tension between the CO2 and brine. More significantly, three organic species, formate, acetate, and oxalate, all three of which are representative species commonly encountered in the saline aquifers that are considered target repositories for carbon sequestration. All three organic species show impacts on wettability, with the organics generally increasing the CO2 wetting of the mineral surface. Not all pure minerals respond the same to the presence of organics, with micas showing a more pronounced influence than quartz. Sandstone and limestone samples aged with different kinds of hydrocarbons, a surrogate for oil-bearing rocks, are generally more CO2-wet, with larger contact angles in the CO2/brine system. Over multiple days, the contact angle decreases, which could be attributed to partitioning

  11. On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

    NASA Astrophysics Data System (ADS)

    Otto, S.; Trautmann, T.; Wendisch, M.

    2010-11-01

    Realistic size equivalence and shape of Saharan mineral dust particles are derived from on in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006), dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10%. At the bottom of the atmosphere (BOA) the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA) depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal) forcing by 55/5% at the TOA over ocean/land and 15% at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20%. Large dust particles significantly contribute to all the radiative effects reported.

  12. Predicting the mineral composition of dust aerosols - Part 2: Model evaluation and identification of key processes with observations

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-10-01

    A global compilation of nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match the fractions of the soil. The MMT is based upon soil measurements after wet sieving, a process that destroys aggregates of soil particles that would have been emitted from the original, undisturbed soil. The second method approximately reconstructs the emitted aggregates. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observations. Only the AMF method exhibits phyllosilicate mass at silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in better agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at distinct clay and silt particle sizes are shown to be more useful for evaluation of the models, in contrast to the sum over all particles sizes that is susceptible to compensating errors, as illustrated by the SMF experiment. Model errors suggest that allocation of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining source of uncertainty. Evaluation of both models and the MMT is hindered by the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. The importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.

  13. Predicting the Mineral Composition of Dust Aerosols. Part 2; Model Evaluation and Identification of Key Processes with Observations

    NASA Technical Reports Server (NTRS)

    Perlwitz, J. P.; Garcia-Pando, C. Perez; Miller, R. L.

    2015-01-01

    A global compilation of nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match the fractions of the soil. The MMT is based upon soil measurements after wet sieving, a process that destroys aggregates of soil particles that would have been emitted from the original, undisturbed soil. The second method approximately reconstructs the emitted aggregates. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observations. Only the AMF method exhibits phyllosilicate mass at silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in better agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at distinct clay and silt particle sizes are shown to be more useful for evaluation of the models, in contrast to the sum over all particles sizes that is susceptible to compensating errors, as illustrated by the SMF experiment. Model errors suggest that allocation of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining source of uncertainty. Evaluation of both models and the MMT is hindered by the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. The importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.

  14. Predicting the mineral composition of dust aerosols - Part 2: Model evaluation and identification of key processes with observations

    NASA Astrophysics Data System (ADS)

    Perlwitz, J. P.; Pérez García-Pando, C.; Miller, R. L.

    2015-02-01

    A global compilation from nearly sixty measurement studies is used to evaluate two methods of simulating the mineral composition of dust aerosols in an Earth system model. Both methods are based upon a Mean Mineralogical Table (MMT) that relates the soil mineral fractions to a global atlas of arid soil type. The Soil Mineral Fraction (SMF) method assumes that the aerosol mineral fractions match those of the soil. The MMT is based upon soil measurements after wet sieving, where soil aggregates are broken into smaller particles. The second method approximately reconstructs the aggregates and size distribution of the original soil that is subject to wind erosion. This model is referred to as the Aerosol Mineral Fraction (AMF) method because the mineral fractions of the aerosols differ from those of the wet-sieved parent soil, partly due to reaggregation. The AMF method remedies some of the deficiencies of the SMF method in comparison to observation. Only the AMF method restores phyllosilicate mass to silt sizes, where they are abundant according to observations. In addition, the AMF quartz fraction of silt particles is in closer agreement with measured values, in contrast to the overestimated SMF fraction. Measurements at separate clay and silt particle sizes are shown to be more useful for evaluation of the models, compared to the sum over all particles sizes that is susceptible to compensating errors in the SMF experiment. Model errors suggest that apportionment of the emitted silt fraction of each mineral into the corresponding transported size categories is an important remaining uncertainty. Substantial uncertainty remains in evaluating both models and the MMT due to the limited number of size-resolved measurements of mineral content that sparsely sample aerosols from the major dust sources. The importance of climate processes dependent upon aerosol mineral composition shows the need for global and routine mineral measurements.

  15. Age and disease-related changes in the mineral of bone.

    PubMed

    Grynpas, M

    1993-01-01

    Bone mineralization changes with age and disease. The distribution of mineral particles in a given bone (mineralization profile) has been studied using density fractionation as well as microradiography and electron backscattering imaging. The biological determinant of mineralization is the rate of turnover. During rapid growth and periods of high remodeling, mineralization is shifted towards lower mineral density (hypomineralization). During aging and periods of low remodeling, mineralization is shifted towards higher mineral densities (hypermineralization). Chemicals can also influence the mineralization profile of bone. Fluoride induces hypermineralization by stabilizing the apatite lattice and reducing bone mineral solubility, whereas strontium induces hypomineralization by loosening the apatite lattice and increasing bone mineral solubility. Drugs such as bisphosphonates induce hypermineralization by inhibiting resorption and acting as crystal poison. Finally, mineralization can be impaired by defects as in rickets and osteomalacia or made excessive by continuous accretion of mineral without resorption as in osteopetrosis. PMID:8275381

  16. Atmospheric transport of mineral dust from the Indo-Gangetic Plain: Temporal variability, acid processing, and iron solubility

    NASA Astrophysics Data System (ADS)

    Srinivas, Bikkina; Sarin, M. M.; Rengarajan, R.

    2014-08-01

    transport of chemical constituents from the Indo-Gangetic Plain (IGP) to the Bay of Bengal is a conspicuous seasonal feature that occurs during the late NE-monsoon (December-March). With this perspective, aerosol composition and abundance of mineral dust have been studied during November 2009 to March 2010 from a sampling site (Kharagpur: 22.3°N, 87.3°E) in the IGP, representing the atmospheric outflow to the Bay of Bengal. The chemical composition of PM2.5 suggests the dominance of nss-SO42- (6.9-24.3 µg m-3); whereas the abundance of mineral dust varied from 3 to 18 µg m-3. The concentration of aerosol iron (FeTot) and its fractional solubility (Fews % = Fews/FeTot *100, where Fews is the water-soluble fraction of FeTot) varied from 60 to 1144 ng m-3 and from 6.7 to 26.5%, respectively. A striking similarity in the temporal variability of total inorganic acidity (TIA = NO3- + nss-SO42-) and Fews (%) provides evidence for acid processing of mineral dust (alluvium) during atmospheric transport from the IGP. The contribution of TIA to water-soluble inorganic species [(nss-SO42- + NO3-)/ΣWSIS], mass ratios of Ca/Al and Fe/Al, and abundance of dust (%) and Fews (%) in the IGP-outflow are similar to the aerosol composition over the Bay of Bengal. With the rapid increase in anthropogenic activities over south and south-east Asia, the enhanced fractional solubility of aerosol iron (attributed to acid processing of mineral dust) has implications to further increase in the air-sea deposition of Fe to the Ocean surface.

  17. Global Distributions of Mineral Dust Properties from SeaWiFS and MODIS: From Sources to Sinks

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Bettenhausen, C.; Sayer, A.

    2011-01-01

    The impact of natural and anthropogenic sources of mineral dust has gained increasing attention from scientific communities in recent years. Indeed, these airborne dust particles, once lifted over the source regions, can be transported out of the boundary layer into the free troposphere and can travel thousands of kilometers across the oceans resulting in important biogeochemical impacts on the ecosystem. Due to the relatively short lifetime (a few hours to about a week), the distributions of these mineral dust particles vary extensively in both space and time. Consequently, satellite observations are needed over both source and sink regions for continuous temporal and spatial sampling of aerosol properties. With the launch of SeaWiFS in 1997, Terra/MODIS in 1999, and Aqua/MODIS in 2002, high quality comprehensive aerosol climatology is becoming feasible for the first time. As a result of these unprecedented satellite data records, studies of the radiative and biogeochemical effects due to dust aerosols are now possible. In this study, we will show the comparisons of satellite retrieved aerosol optical thickness using Deep Blue algorithm with data from AERONET sunphotometers over desert and semi-desert regions as well as vegetated areas. Our results indicate reasonable agreements between these two. These new satellite products will allow scientists to determine quantitatively the aerosol properties near sources using high spatial resolution measurements from Sea WiFS and MODIS-like instruments. The multiyear satellite measurements since 1997 from Sea WiFS will be compared with those retrieved from MODIS and MISR, and will be utilized to investigate the interannual variability of source, pathway, and dust loading associated with the dust outbreaks over the entire globe. Finally, the trends observed over the last decade based upon the SeaWiFS time series in the amounts of tropospheric aerosols due to natural and anthropogenic sources (such as changes in the frequency

  18. Parameterization of heterogeneous ice nucleation on mineral dust particles: An application in a regional scale model

    NASA Astrophysics Data System (ADS)

    Niemand, M.; Vogel, B.; Vogel, H.; Connolly, P.; Klein, H.; Bingemer, H.; Hoose, C.; Moehler, O.; Leisner, T.

    2010-12-01

    In climate and weather models, the quantitative description of aerosol and cloud processes relies on simplified assumptions. This contributes major uncertainties to the prediction of global and regional climate change. The parameterization of heterogeneous ice nucleation is a step towards improving our current knowledge of the importance of the cloud ice phase in weather and climate models and can aid in the theoretical understanding of such processes. This contribution presents a new parameterization derived from a large number of experiments carried out at the aerosol and cloud chamber facility AIDA [1] of Karlsruhe Institute of Technology. AIDA is especially suitable to study ice nucleation processes at tropospheric and stratospheric cloud conditions covering a wide range of temperature and pressure. During pumping expansion, cooling rates between -0.3 and -5.0 K/min, equating to vertical wind velocities of 0.5 to 8 m/s, and a relative humidity range of up to more than 200% with respect to ice can be reached. The parameterization is valid for the temperature range -35°C to -15°C. In order to derive and test the parameterization a parameter called the ice-active surface site density was calculated for a number of different experiments with mineral dust acting as ice nuclei in the immersion and/or deposition mode. An exponential function was fitted to this data of ice-active surface site density vs. temperature. The curve fit was then used within the bin microphysical model ACPIM [2] to simulate the ice formation rates from the experiments. The major dust outbreak over the Sahara in May 2008 which was followed by a dust transport over the Mediterranean and Western Europe was simulated using the regional scale online coupled model system COSMO-ART (Vogel et al., 2009). Based on the model results the exponential curve fit was used to calculate the ice nuclei number concentration at Kleiner Feldberg (Germany). The results will be compared to measurements from

  19. Chest radiography in dust-exposed miners: Promise and problems, potential and imperfections

    SciTech Connect

    Wagner, G.R.; Attfield, M.D.; Parker, J.E. )

    1993-01-01

    Since the early 1900s, it was recognized that many dust-exposed workers developed abnormal radiographs during life. Chest radiography remains the primary means of determining the presence and extent of dust-induced pneumoconiosis, although it is ineffective for detecting airways obstructions from mine dust exposure. This chapter reviews the uses and limitations of chest radiography in the study, surveillance, screening, clinical diagnosis, and disability determinations of occupational lung diseases in dust-exposed workers. 70 refs.

  20. Imaginary refractive index and other microphysical properties of volcanic ash, Sarahan dust, and other mineral aerosols

    NASA Astrophysics Data System (ADS)

    Rocha Lima, A.; Martins, J.; Krotkov, N. A.; Artaxo, P.; Todd, M.; Ben Ami, Y.; Dolgos, G.; Espinosa, R.

    2013-12-01

    Aerosol properties are essential to support remote sensing measurements, atmospheric circulation and climate models. This research aims to improve the understanding of the optical and microphysical properties of different types of aerosols particles. Samples of volcanic ash, Saharan dust and other mineral aerosols particles were analyzed by different techniques. Ground samples were sieved down to 45um, de-agglomerated and resuspended in the laboratory using a Fluidized Bed Aerosol Generator (FBAG). Particles were collected on Nuclepore filters into PM10, PM2.5, or PM1.0. and analyzed by different techniques, such as Scanning Electron Microscopy (SEM) for determination of size distribution and shape, spectral reflectance for determination of the optical absorption properties as a function of the wavelength, material density, and X-Ray fluorescence for the elemental composition. The spectral imaginary part of refractive index from the UV to the short wave infrared (SWIR) wavelength was derived empirically from the measurements of the spectral mass absorption coefficient, size distribution and density of the material. Some selected samples were also analyzed with the Polarized Imaging Nephelometer (PI-Neph) instrument for the characterization of the aerosol polarized phase function. This work compares results of the spectral refractive index of different materials obtained by our methodology with those available in the literature. In some cases there are significant differences both in magnitude and spectral dependence of the imaginary refractive index. These differences are evaluated and discussed in this work.

  1. Mineral phases and metals in baghouse dust from secondary aluminum production.

    PubMed

    Huang, Xiao-Lan; El Badawy, Amro M; Arambewela, Mahendranath; Adkins, Renata; Tolaymat, Thabet

    2015-09-01

    Baghouse dust (BHD) is a solid waste generated by air pollution control systems during secondary aluminum processing (SAP). Management and disposal of BHD can be challenging in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 78 BHD samples collected from 13 different SAP facilities across the U.S. were investigated. The XRD semi-quantitative analysis of BHD samples suggests the presence of metallic aluminum, aluminum oxide, aluminum nitride and its oxides, spinel, elpasolite as well as diaspora. BHD also contains halite, sylvite and fluorite, which are used as fluxes in SAP activities. Total aluminum (Al) in the BHD samples averaged 18% by weight. Elevated concentrations of trace metals (>100 μg L(-1) As; >1000 μg L(-1) Cu, Mn, Se, Pb, Mn and Zn) were also detected in the leachate. The U.S. toxicity characteristic leaching procedure (TCLP) results showed that some samples leached above the toxicity limit for Cd, Pb and Se. Exceeding the TCLP limits in all sample is independent of facilities generating the BHD. From the metal content perspective only, it appears that BHD has a higher potential to exhibit toxicity characteristics than salt cake (the largest waste stream generated by SAP facilities). PMID:25898346

  2. CYTOTOXIC EFFECTS OF SOME MINERAL DUSTS ON SYRIAN HAMSTER PERITONEAL MACROPHAGES

    PubMed Central

    Bey, Elke; Harington, J. S.

    1971-01-01

    Hamster peritoneal macrophages were grown in cell culture and their response to various conditions was examined. The cultures responded favorably to high concentrations of serum and to medium which had been preconditioned by contact with tumor cells. After 2–3 days of adaptation, they entered into a period of stability which lasted from the 4th to the 9th day. Macrophage cultures in this stable phase were treated with various samples of mineral dusts and their response determined by counting the number of viable macrophages/cm2 at intervals over a period of 72 hr. Crystalline silica Snowit was found to be nontoxic. Amorphous silica Fransil caused a characteristic cytotoxic effect and a rapid decline in cell population at doses less than 150 µg/5 x 105 cells. Of the three different kinds of asbestos used, chrysotile was toxic and amosite and crocidolite nontoxic at equivalent concentrations. A comparison of two preparations of chrysotile which differed in surface area showed that weight rather than surface area determines toxicity. Pretreatment of chrysotile with tryptose phosphate broth under drastic conditions accelerated but did not increase the final intensity of the cytotoxic effect. PMID:4101804

  3. Mineral phases and metals in baghouse dust from secondary aluminum production.

    PubMed

    Huang, Xiao-Lan; El Badawy, Amro M; Arambewela, Mahendranath; Adkins, Renata; Tolaymat, Thabet

    2015-09-01

    Baghouse dust (BHD) is a solid waste generated by air pollution control systems during secondary aluminum processing (SAP). Management and disposal of BHD can be challenging in the U.S. and elsewhere. In this study, the mineral phases, metal content and metal leachability of 78 BHD samples collected from 13 different SAP facilities across the U.S. were investigated. The XRD semi-quantitative analysis of BHD samples suggests the presence of metallic aluminum, aluminum oxide, aluminum nitride and its oxides, spinel, elpasolite as well as diaspora. BHD also contains halite, sylvite and fluorite, which are used as fluxes in SAP activities. Total aluminum (Al) in the BHD samples averaged 18% by weight. Elevated concentrations of trace metals (>100 μg L(-1) As; >1000 μg L(-1) Cu, Mn, Se, Pb, Mn and Zn) were also detected in the leachate. The U.S. toxicity characteristic leaching procedure (TCLP) results showed that some samples leached above the toxicity limit for Cd, Pb and Se. Exceeding the TCLP limits in all sample is independent of facilities generating the BHD. From the metal content perspective only, it appears that BHD has a higher potential to exhibit toxicity characteristics than salt cake (the largest waste stream generated by SAP facilities).

  4. Synchrotron FTIR Examination of Interplanetary Dust Particles: An Effort to Determine the Compounds and Minerals in Interstellar and Circumstellar Dust

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.

    2002-01-01

    Some interplanetary dust particles (IDPs), collected by NASA from the Earth's stratosphere, are the most primitive extraterrestrial material available for laboratory analysis. Many exhibit isotopic anomalies in H, N, and O, suggesting they contain preserved interstellar matter. We report the preliminary results of a comparison of the infrared absorption spectra of subunits of the IDPs with astronomical spectra of interstellar grains.

  5. On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations

    NASA Astrophysics Data System (ADS)

    Otto, S.; Trautmann, T.; Wendisch, M.

    2011-05-01

    Realistic size equivalence and shape of Saharan mineral dust particles are derived from in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006), dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10 %. At the bottom of the atmosphere (BOA) the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA) depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal) forcing by 55/5 % at the TOA over ocean/land and 15 % at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20 %. Large dust particles significantly contribute to all the radiative effects reported. They strongly enhance the absorbing properties and forward scattering in the solar and increase predominantly, e.g., the total TOA forcing of the dust over land.

  6. Coal miners' mortality in relaton to radiological category, lung function and exposure to airborne dust. Final report

    SciTech Connect

    Miller, B.G.; Jacobsen, M.; Steele, R.C.

    1981-06-01

    This report describes mortality among 29,553 British coal miners. They represent 93.5% of 31,611 men who were surveyed radiologically at 24 coal mines in the period 1953 through 1958. The main aim of the work was to consider risks of death attributed to various underlying causes, as recorded on death certificates, in relation to radiological signs of pneumoconiosis, measures of lung function, and exposure to respirable coal mine dust.

  7. Interactions of mineral dust with pollution and clouds: An individual-particle TEM study of atmospheric aerosol from Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Pósfai, Mihály; Axisa, Duncan; Tompa, Éva; Freney, Evelyn; Bruintjes, Roelof; Buseck, Peter R.

    2013-03-01

    Aerosol particles from desert dust interact with clouds and influence climate on regional and global scales. The Riyadh (Saudi Arabia) aerosol campaign was initiated to study the effects of dust particles on cloud droplet nucleation and cloud properties. Here we report the results of individual-particle studies of samples that were collected from an aircraft in April 2007. We used analytical transmission electron microscopy, including energy-dispersive X-ray spectrometry, electron diffraction, and imaging techniques for the morphological, chemical, and structural characterization of the particles. Dust storms and regional background conditions were encountered during four days of sampling. Under dusty conditions, the coarse (supermicrometer) fraction resembles freshly crushed rock. The particles are almost exclusively mineral dust grains and include common rock-forming minerals, among which clay minerals, particularly smectites, are most abundant. Unaltered calcite grains also occur, indicating no significant atmospheric processing. The particles have no visible coatings but some contain traces of sulfur. The fine (submicrometer) fraction is dominated by particles of anthropogenic origin, primarily ammonium sulfate (with variable organic coating and some with soot inclusions) and combustion-derived particles (mostly soot). In addition, submicrometer, iron-bearing clay particles also occur, many of which are internally mixed with ammonium sulfate, soot, or both. We studied the relationships between the properties of the aerosol and the droplet microphysics of cumulus clouds that formed above the aerosol layer. Under dusty conditions, when a large concentration of coarse-fraction mineral particles was in the aerosol, cloud drop concentrations were lower and droplet diameters larger than under regional background conditions, when the aerosol was dominated by submicrometer sulfate particles.

  8. Clear Sky Column Closure Studies of Urban-Marine and Mineral-Dust Aerosols Using Aircraft, Ship, Satellite and Ground-Based Measurements in ACE-2

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Russell, Philip B.; Livingston, John M.; Gasso, Santiago; Hegg, Dean A.; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Oestroem, Elisabeth; Noone, Kevin J.; Durkee, Philip A.; Jonsson, Haflidi H.; Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Formenti, Paola; Andreae, Meinrat O.; Kapustin, Vladimir N.; Bates, Timothy S.; Quinn, Patricia K.

    2000-01-01

    As part of the second Aerosol Characterization Experiment (ACE-2), European urban-marine and African mineral-dust aerosols were measured aboard the Pelican aircraft, the Research Vessel Vodyanitskiy from the ground and from satellites.

  9. Mineral magnetism of atmospheric dust over southwest coast of India: Impact of anthropogenic activities and implications to public health

    NASA Astrophysics Data System (ADS)

    Warrier, Anish Kumar; Shankar, R.; Manjunatha, B. R.; Harshavardhana, B. G.

    2014-03-01

    We have used rock magnetic techniques in this study to assess atmospheric pollution at five stations in and around Mangalore city on the southwestern coast of India. Samples of dust were collected from two suburban areas (Thokkottu and Pumpwell located respectively ~ 10 km and 3 km from the city center), the city center itself (Milagres) and industrial/port areas (Panambur and Mangalore Refinery and Petrochemicals Limited (MRPL)). Low-frequency magnetic susceptibility (χlf), frequency-dependent susceptibility (χfd), susceptibility of anhysteretic remanent magnetization (χARM) and isothermal remanent magnetization (IRM 20 to 1000 mT) were determined on 23 dust samples and inter-parametric ratios calculated. Results show that samples from suburban areas (particularly Thokkottu) are characterized by low χlf (< 314.1 × 10- 8 m3 kg- 1) and up to 6% χfd, suggesting low levels of pollution and the presence of pedogenic magnetite possibly derived from soils by wind erosion. However, the average χlf of Milagres, Panambur and MRPL dust samples is high by factors of 9.2, 3.3 and 2.6 compared to that of the Thokkottu sample. The Milagres sample contains magnetically "soft" minerals like magnetite, possibly indicating its derivation from motor vehicle exhaust. In contrast, the Panambur dust sample is characterized by magnetically "hard" minerals such as hematite and goethite as it has an 8-fold higher HIRM value compared to the Thokkottu sample. This magnetic signature is perhaps the result of dust particles derived from the grinding of hematite-rich iron ore by the Kudremukh Iron Ore Company Limited (KIOCL) at Panambur and its storage and export through the nearby New Mangalore Port. However, the dust sample from MRPL has magnetically "soft" minerals like magnetite. This magnetic mineral may have originated from petroleum refining processes at MRPL. Particulate pollution from industrial activities and motor vehicle exhaust is a threat to human health and is known to

  10. Scavenging of pollutant acid substances by Asian mineral dust particles - article no. L07816

    SciTech Connect

    Matsumoto, J.; Takahashi, K.; Matsumi, Y.; Yabushita, A.; Shimizu, A.; Matsui, I.; Sugimoto, N.

    2006-04-13

    Uptakes of sulfate and nitrate onto Asian dust particles during transport from the Asian continent to the Pacific Ocean were analyzed by using a single-particle time-of-flight mass spectrometer. Observation was conducted at Tsukuba in Japan in the springtime of 2004. Sulfate-rich dust particles made their largest contribution during the 'dust event' in the middle of April 2004. As a result of detailed analysis including backward trajectory calculations, it was confirmed that sulfate components originating from coal combustion in the continent were internally mixed with dust particles. Even in the downstream of the outflow far from the continental coastline, significant contribution of Asian dust to sulfate was observed. Asian dust plays critical roles as the carrier of sulfate over the Pacific Ocean.

  11. Atmospheric aging of dust ice nucleating particles - a combined laboratory and field approach

    NASA Astrophysics Data System (ADS)

    Boose, Yvonne; Rodríguez, Sergio; García, M. Isabel; Linke, Claudia; Schnaiter, Martin; Zipori, Assaf; Crawford, Ian; Lohmann, Ulrike; Kanji, Zamin A.; Sierau, Berko

    2016-04-01

    than the rather fresh dust at Izaña. This suggests that atmospheric aging and processing decreases the ice nucleation efficiency of Saharan dust during advection to Central Europe.

  12. MISR Decadal Observations of Mineral Dust: Property Characterization and Climate Applications

    NASA Technical Reports Server (NTRS)

    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.

  13. Dust Provenance and Radiometric U-Series Ages as Evidence for an Eemian Ice Sheet in Greenland

    NASA Astrophysics Data System (ADS)

    Aciego, S.; Bourdon, B.; Schwander, J.; Stocker, T. F.

    2009-12-01

    The mineralogy and geochemistry of air-transported mineral particles, dust, reflect the prior history of the source material as well as influence the chemistry of the settling locations (rivers, ice sheets and ultimately the oceans). When applied to ice sheets, the atmospheric circulation patterns gleaned from the chemical characteristics of the dust may provide some additional constraints on size and shape of paleo-ice sheets. Furthermore, the ice bound dust grains can be used to determine the age of the ice by using uranium series recoil as a radiometric dating method, provided there is sufficient information about the size and shape of the dust grains and the [U] concentration and isotopic (234U/238U) composition of the ice and dust. The Dye3 ice core is the southern-most deep ice core in Greenland, so should provide a minimum estimate of ice sheet size in the past: the existence of ice is evidence for an ice sheet at any given time. A series of samples from 200 m to 2030 m in depth were analyzed by MC-ICPMS and TIMS for U concentrations and 234U/238U as well as 176Hf/177Hf, 87Sr/86Sr, and 143Nd/144Nd. The radiogenic isotopic compositions of the insoluble dust found in the upper 1800 m falls within the range of previously measured Greenland dust samples: 87Sr/86Sr = 0.7108 - 0.7174, ɛNd = -9.7 - -13.6, and ɛHf = -2 - -5. However, the data trends toward significantly more unradiogenic Nd and Hf and radiogenic Sr values in the lower 100 m: 87Sr/86Sr = 0.7167 - 0.7200, ɛNd = -15.62 - -17.36, and ɛHf = -21 - -25; the deepest sample containing basal sediments having the most extreme values: 87Sr/86Sr = 0.7349 - 0.7785 ɛNd = -37.48 - -41.61, and ɛHf = -24.8 - -39.54. The calculated 234U/238U radiometric age for the deepest ice ranges from 90 to 110 ± 50 ka, in the same range as two possible age models for the Dye3 location, indicating the deepest ice is in the range of 40-60 ka or 85-120 ka. However, based on the radiogenic isotopes, while the dust in the

  14. Abrupt Late Holocene Shift in Atmospheric Circulation Recorded by Mineral Dust in the Siple Dome Ice Core, Antarctica

    NASA Astrophysics Data System (ADS)

    Koffman, B. G.; Goldstein, S. L.; Kaplan, M. R.; Winckler, G.; Bory, A. J. M.; Biscaye, P.

    2015-12-01

    Atmospheric dust directly influences Earth's climate by altering the radiative balance and by depositing micronutrients in the surface ocean, affecting global biogeochemical cycling. In addition, mineral dust particles provide observational evidence constraining past atmospheric circulation patterns. Because dust can originate from both local and distant terrestrial sources, knowledge of dust provenance can substantially inform our understanding of past climate history, atmospheric transport pathways, and differences in aerosol characteristics between glacial and interglacial climate states. Dust provenance information from Antarctic ice cores has until now been limited to sites in East Antarctica. Here we present some of the first provenance data from West Antarctica. We use Sr-Nd isotopes to characterize dust extracted from late Holocene ice (~1000-1800 C.E.) from the Siple Dome ice core. The data form a tight array in Sr-Nd isotope space, with 87Sr/86Sr ranging between ~0.7087 and 0.7102, and ɛNd ranging between ~ -7 and -16. This combination is unique for Antarctica, with low Nd and low Sr isotope ratios compared to high-elevation East Antarctic sites, requiring a dust source from ancient (Archean to early Proterozoic) and unweathered continental crust, which mixes with young volcanic material. Both components are likely sourced from Antarctica. We also observe significant, systematic variability in Sr and Nd isotopic signatures through time, reflecting changes in the mixing ratio of these sources, and hypothesize that these changes are driven by shifts in circulation patterns. A large change occurs over about 10 years at ca. 1125 C.E. (ΔɛNd = +3 and Δ87Sr/86Sr = -0.0014). This shift coincides with changes in climate proxies in Southern Hemisphere paleoclimate records reflecting variability in the Westerlies. We therefore interpret the shift in dust provenance at Siple Dome to be related to larger-scale circulation changes. In general, the observed shifts

  15. A comparison of the physical and optical properties of anthropogenic air pollutants and mineral dust over Northwest China

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Pu, Wei; Shi, Jinsen; Bi, Jianrong; Zhou, Tian; Zhang, Xueying; Ren, Yong

    2015-04-01

    Emissions of mineral dust and its mixing with anthropogenic air pollutants affect both regional and global climates. Our fieldwork in late spring 2007 (April 25-June 15) measured the physical and optical properties of dust storms mixed with local air pollutants at a rural site about 48 km southeast of central Lanzhou. Levels of air pollutants and aerosol optical properties were observed during the experiment, with concentrations of NOx (6.8 ± 3.3 ppb, average ± standard deviation), CO (694 ± 486 ppb), SO2 (6.2 ± 10 ppb), O3 (50.7 ± 13.1 ppb), and PM10 (172 ± 180 μg m-3), and aerosol scattering coefficient (164 ± 89 Mm-1; 1 Mm = 106 m) and absorption coefficient (11.7 ± 6.6 Mm-1), all much lower than the values observed during air pollution episodes in urban areas. During a major dust storm, the mass concentration of PM10 reached 4072 μg m-3, approximately 21-fold higher than in non-dust storm periods. The mixing ratios of trace gases declined noticeably after a cold front passed through. The observed CO/SO2 and CO/NOx ratios during air pollution episodes were 4.2-18.3 and 13.7-80.5, respectively, compared with the corresponding ratios of 38.1-255.7 and 18.0-245.9 during non-pollution periods. Our investigations suggest that dust storms have a significant influence on air quality in areas far from their source, and this large-scale transport of dust and air pollutants produces major uncertainties in the quantification of the global effects of emissions over Northwest China.

  16. Minerals

    MedlinePlus

    Minerals are important for your body to stay healthy. Your body uses minerals for many different jobs, including building bones, making ... regulating your heartbeat. There are two kinds of minerals: macrominerals and trace minerals. Macrominerals are minerals your ...

  17. Colloidal stability of nanoparticles derived from simulated cloud-processed mineral dusts.

    PubMed

    Kadar, Enikö; Fisher, Andrew; Stolpe, Björn; Calabrese, Sergio; Lead, Jamie; Valsami-Jones, Eugenia; Shi, Zongbo

    2014-01-01

    Laboratory simulation of cloud processing of three model dust types with distinct Fe-content (Moroccan dust, Libyan dust and Etna ash) and reference goethite and ferrihydrite were conducted in order to gain a better understanding of natural nanomaterial inputs and their environmental fate and bioavailability. The resulting nanoparticles (NPs) were characterised for Fe dissolution kinetics, aggregation/size distribution, micromorphology and colloidal stability of particle suspensions using a multi-method approach. We demonstrated that the: (i) acid-leachable Fe concentration was highest in volcanic ash (1 m Mg(-1) dust) and was followed by Libyan and Moroccan dust with an order of magnitude lower levels; (ii) acid leached Fe concentration in the<20 nm fraction was similar in samples processed in the dark with those under artificial sunlight, but average hydrodynamic diameter of NPs after cloud-processing (pH~6) was larger in the former; iii) NPs formed at pH~6 were smaller and less poly-disperse than those at low pH, whilst unaltered zeta potentials indicated colloidal instability; iv) relative Fe percentage in the finer particles derived from cloud processing does not reflect Fe content of unprocessed dusts (e.g. volcanic ash>Libyan dust). The common occurrence of Fe-rich "natural nanoparticles" in atmospheric dust derived materials may indicate their more ubiquitous presence in the marine environment than previously thought.

  18. Radiative impact of mineral dust on monsoon precipitation variability over West Africa

    SciTech Connect

    Zhao, Chun; Liu, Xiaohong; Leung, Lai-Yung R.; Hagos, Samson M.

    2011-03-01

    The radiative forcing of dust and its impact on precipitation over the West Africa monsoon (WAM) region is simulated using a coupled meteorology and aerosol/chemistry model (WRF-Chem). During the monsoon season, dust is a dominant contributor to AOD over West Africa. In the standard simulation, on 24-hour domain average, dust has a cooling effect (-6.11 W/m2) at the surface, a warming effect (6.94 W/m2) in the atmosphere, and a relatively small TOA forcing (0.83 W/m2). Dust modifies the surface energy budget and atmospheric diabatic heating and hence causes lower atmospheric cooling in the daytime but warming in the nighttime. As a result, atmospheric stability is increased in the daytime and reduced in the nighttime, leading to a reduction of late afternoon precipitation by up to 0.14 mm/hour (30%) and an increase of nocturnal and early morning precipitation by up to 0.04 mm/hour (23%) over the WAM region. Dust-induced reduction of diurnal precipitation variation improves the simulated diurnal cycle of precipitation when compared to measurements. However, daily precipitation is only changed by a relatively small amount (-0.14 mm/day or -4%). On the other hand, sensitivity simulations show that, for weaker-to-stronger absorbing dust, dust longwave warming effect in the nighttime surpasses its shortwave cooling effect in the daytime at the surface, leading to a less stable atmosphere associated with more convective precipitation in the nighttime. As a result, the dust-induced change of daily WAM precipitation varies from a significant reduction of -0.40 mm/day (-12%, weaker absorbing dust) to a small increase of 0.05 mm/day (1%, stronger absorbing dust). This variation originates from the competition between dust impact on daytime and nighttime precipitation, which depends on dust shortwave absorption. Dust reduces the diurnal variation of precipitation regardless of its absorptivity, but more reduction is associated with stronger absorbing dust.

  19. Evaluation of a regional mineral dust model over Northern Africa, Southern Europe and Middle East with AERONET data

    NASA Astrophysics Data System (ADS)

    Basart, S.; Pérez, C.; Cuevas, E.; Baldasano, J. M.

    2009-04-01

    the model to reproduce AOD (at 550nm) associated to mineral dust 24, 48 and 72h ahead. A suit of discrete statistics as Mean Normalized Bias Error (MNBE), Mean Normalized Gross Error (MNGE) and Root Mean Square Error (RMSE) has been used in order to evaluate the model behaviour. Categorical statistics or skill scores, as model accuracy, bias, probability of detection, false alarm rate and critical success index have been implemented to test the capability of the model to simulate AOD exceeding thresholds defined by the quartiles of each AERONET site. A previous aerosol characterization of AERONET data has been performed for our study region in order to discriminate desert dust contributions (Basart et al., 2008). The first results of the comparison reveal that the modelled dust field agrees in general reasonably well with sun photometer data. Since dust long-range transport is mainly driven by smaller dust particles, the results of this new 8-bins version (with increased number of dust size bins) is considerably better, since the small particle size range (<10µm effective radius) is well described. The best scores are found in North Africa and Middle East. In the Sahel region, an important sub-estimation is observed in wintertime, when the Atlantic outflow transport is important. This is partially due to the more complex processes associated to dust generation in this region (Warren et al., 2007), not well parameterized in dust models yet. Other causes, such as the correct simulation of regional winds or the threshold friction velocity are under research. Moreover, the interaction of mineral dust and biomass burning aerosols from Savannah fires is at its maximum over the region in this season. In southern Europe, the relative errors are higher than in the rest of our study domain mainly due to the presence of different types of aerosols (such as fine pollution aerosols) which appear well-mixed with desert dust. References: Basart, S., C. Pérez, E. Cuevas and J

  20. Modeling of the mineral contribution of dust to PM10 directly from the measurements of VIIRS Aerosol Optical Thickness

    NASA Astrophysics Data System (ADS)

    Albina, D. T.

    2015-12-01

    Northern Africa is well known as the largest producing region of dust, which is transported across the Atlantic to the Caribbean, under specific weather conditions. Saharan dust was observed, over the Caribbean Basin, to try to determine the roles they may play in human health, and in the fertilization of Amazon Forest. Scientists have not only used the satellite sensors MODIS and VIIRS to measure the volume of dust that makes this trans-Atlantic journey, but also the AERONET network of photometers, and PM10 Suspended Particulate Matter. We have successfully compared and shown a high correlation between the measurements from VIIRS aerosol optical thickness (AOT) and PM10 so that to be able to determine an accurate modeling of the mineral contribution of dust to PM10 directly from the measurements of VIIRS. The aim of this work is to show that it is possible to accurately forecast the daily mean concentration of PM10 using linear regression models. In this way, countries of the Caribbean region which cannot afford Particle Sensor for Pm10 will be able to have a precise idea of the PM10 daily forecast upon there region.

  1. Cross-shift peak expiratory flow changes are unassociated with respirable coal dust exposure among South African coal miners

    SciTech Connect

    Naidoo, R.N.; Robins, T.G.; Becklake, M.; Seixas, N.; Thompson, M.L.

    2007-12-15

    he objectives of this study were to determine whether cross-shift changes in peak expiratory flow rate (PEFR) were related to respirable dust exposure in South African coalminers. Fifty workers were randomly selected from a cohort of 684 miners from 3 bituminous coal mines in Mpumalanga, South Africa. Peak expiratory efforts were measured prior to the commencement of the shift, and at the end of the shift on at least two occasions separated by at least 2 weeks, with full shift personal dust sampling being conducted on each occasion for each participant. Interviews were conducted, work histories were obtained and cumulative exposure estimates were constructed. Regression models examined the associations of cross-shift changes in PEFR with current and cumulative exposure, controlling for shift, smoking and past history of tuberculosis. There were marginal differences in cross-shift PEFR (ranging from 0.1 to 2 L/min). Linear regression analyses showed no association between cross-shift change in PEFR and current or cumulative exposure. The specific shift worked by participants in the study showed no effect. Our study showed no association between current respirable dust exposure and cross-shift changes in PEFR. There was a non-significant protective effect of cumulative dust exposure on the outcome, suggesting the presence of a 'healthy worker survivor effect' in this data.

  2. Pneumoconiosis, lung function and exposure to airborne dust: epidemiological research to compare responses of working coalminers with responses of ex-miners. Part 2. Final report

    SciTech Connect

    Soutar, C.A.; Maclaren, W.; Hurley, F.; Murdoch, R.; Hadden, G.

    1982-03-01

    The relationship between dust exposure and disease for miners was compared with that for ex-miners, in order to determine whether relationships found in other studies on miners alone could be applied to both groups. 17,738 men examined in the 1950s were followed up approximately 22 years later. Sixty one per cent of the survivors were examined, being 40% of the original sample. Records were made of respiratory symptoms, smoking habit, lung spirometry and chest radiograph findings. Radiographs were interpreted according to the International Labour Office Classification of Pneumoconiosis. Lifetime dust exposure was calculated for each subject. The dust/disease relationship was found to be the same for both groups. Ex-miners were found to have more pneumoconiosis and fibrosis and to be in worse health than miners. Pneumoconiosis progression was shown to be related to continued dust exposure; fibrosis progression was related to the presence of dust in the lungs. Dust exposure was shown to cause a mainly restrictive pattern of lung disease in contrast to the obstructive pattern caused by smoking. Colliery-related differences were found in lung disease which it was felt needed further investigation.

  3. Bone Mineral Density in Healthy Female Adolescents According to Age, Bone Age and Pubertal Breast Stage

    PubMed Central

    Moretto, M.R; Silva, C.C; Kurokawa, C.S; Fortes, C.M; Capela, R.C; Teixeira, A.S; Dalmas, J.C; Goldberg, T.B

    2011-01-01

    Objectives: This study was designed to evaluate bone mineral density (BMD) in healthy female Brazilian adolescents in five groups looking at chronological age, bone age, and pubertal breast stage, and determining BMD behavior for each classification. Methods: Seventy-two healthy female adolescents aged between 10 to 20 incomplete years were divided into five groups and evaluated for calcium intake, weight, height, body mass index (BMI), pubertal breast stage, bone age, and BMD. Bone mass was measured by bone densitometry (DXA) in lumbar spine and proximal femur regions, and the total body. BMI was estimated by Quetelet index. Breast development was assessed by Tanner’s criteria and skeletal maturity by bone age. BMD comparison according to chronologic and bone age, and breast development were analyzed by Anova, with Scheffe’s test used to find significant differences between groups at P≤0.05. Results: BMD (g·cm-2) increased in all studied regions as age advanced, indicating differences from the ages of 13 to 14 years. This group differed to the 10 and 11 to 12 years old groups for lumbar spine BMD (0.865±0.127 vs 0.672±0.082 and 0.689±0.083, respectively) and in girls at pubertal development stage B3, lumbar spine BMD differed from B5 (0.709±0.073 vs 0.936±0.130) and whole body BMD differed from B4 and B5 (0.867±0.056 vs 0.977±0.086 and 1.040±0.080, respectively). Conclusion: Bone mineralization increased in the B3 breast maturity group, and the critical years for bone mass acquisition were between 13 and 14 years of age for all sites evaluated by densitometry. PMID:21966336

  4. 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

    NASA Astrophysics Data System (ADS)

    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 < 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% in

  5. Optical and microphysical properties of mineral dust and biomass burning aerosol observed over Warsaw on 10th July 2013

    NASA Astrophysics Data System (ADS)

    Janicka, Lucja; Stachlewska, Iwona; Veselovskii, Igor; Baars, Holger

    2016-04-01

    Biomass burning aerosol originating from Canadian forest fires was widely observed over Europe in July 2013. Favorable weather conditions caused long-term westward flow of smoke from Canada to Western and Central Europe. During this period, PollyXT lidar of the University of Warsaw took wavelength dependent measurements in Warsaw. On July 10th short event of simultaneous advection of Canadian smoke and Saharan dust was observed at different altitudes over Warsaw. Different origination of both air masses was indicated by backward trajectories from HYSPLIT model. Lidar measurements performed with various wavelength (1064, 532, 355 nm), using also Raman and depolarization channels for VIS and UV allowed for distinguishing physical differences of this two types of aerosols. Optical properties acted as input for retrieval of microphysical properties. Comparisons of microphysical and optical properties of biomass burning aerosols and mineral dust observed will be presented.

  6. Field Observation of Heterogeneous Formation of Secondary Organic Aerosols on Asian Mineral Dust Surfaces

    NASA Astrophysics Data System (ADS)

    Wang, G.

    2014-12-01

    This study investigated the heterogeneous formation mechanism of secondary organic aerosols (SOA) on dust surfaces by characterizing molecular compositions and size distributions of dicarboxylic acids, keto-carboxylic acids, a-dicarbonyls and inorganic ions in size-segregated aerosols (9-stages) in the urban atmosphere of Xi'an, China during dust storm periods and comparing with those in non-dust storm periods. In the presence of a dust storm, all the above mentioned SOA species in Xi'an are predominantly enriched on coarse particles (>2.1 µm). Oxalic acid well correlated with NO3- (r2=0.72, p<0.01) rather than SO42-. This phenomenon differs greatly from the observed particles during a non-dust storm period, which is characterized by an enrichment of the SOA on fine particles (<2.1 µm) with a strong correlation between C2 and SO42-. We propose a three-step formation pathway to explain these observations as follows. First, nitric acid and nitrogen oxides react with dust to form a liquid film on the surface via water vapor-absorption of calcium nitrate. Second, gaseous Gly and mGly partition into the aqueous-phase. Finally, the aqueous-phase Gly and mGly oxidize into glyoxylic acid (wC2), followed by a further oxidation into C2. To the best of our knowledge, we found for the first time the enrichments of glyoxal (Gly) and methylglyoxal (mGly) on dust surfaces. Our data indicate a more critical role of nitrate than sulfate in the heterogeneous formation process of SOA on dust surfaces. Mass ratio of C2 to wC2 was found to be higher in coarse particles than in fine particles during the dust storm events, which is due to low acidity condition of large particles that is favorable for conversion of wC2 to C2.

  7. Theoretical investigation on the role of mineral dust aerosol in atmospheric reaction: A case of the heterogeneous reaction of formaldehyde with NO2 onto SiO2 dust surface

    NASA Astrophysics Data System (ADS)

    Ji, Yuemeng; Wang, Honghong; Li, Guiying; An, Taicheng

    2015-02-01

    The role of mineral dusts on the heterogeneous reaction of formaldehyde with NO2 was investigated using a quantum chemical approach. SiO2 was selected as a model of mineral dust to investigate the heterogeneous reaction mechanism and kinetics because the mineral dust is comprised of ∼60% of SiO2. Compared with NO2, formaldehyde was easily adsorbed onto SiO2 model, indicating SiO2 was a sink for formaldehyde. Further data showed that the presence of SiO2 reduced the reaction barrier, but did not change reaction mechanism. The kinetics calculation using the canonical variational transition state theory plus small curvature tunneling correction showed that the presence of SiO2 could accelerate the atmospheric reaction rate of formaldehyde with NO2 to produce HONO. The effect of the altitudes was also considered, and the heterogeneous reaction rate decreased with increasing the altitude due to the atmospheric temperature decrease, suggesting that the degradation of atmospheric HCHO onto available mineral dusts might be competitive with the corresponding homogeneous reaction, especially in dusty urban and desert environments. This work can lay the foundation on the atmospheric heterogeneous reaction of VOCs, probe the role of mineral dust and establish the atmospheric transformation models, to better understand pollution mechanism.

  8. Separating Continental Mineral Dust from Cosmic Dust using Platinum Group Element Concentrations and Osmium Isotopes in Ancient Polar Ice

    NASA Astrophysics Data System (ADS)

    Seo, J. H.; Jackson, B.; Osterberg, E. C.; Sharma, M.

    2015-12-01

    The platinum group element (PGEs: Pt, Pd, Rh, Ir, Os, and Ru) accumulation in ancient polar archives have been argued to trace cosmic dust and "smoke" from larger meteors but the PGE concentration data lack specificity. For example, the extent to which the terrestrial volcanism/dust has contributed to the PGE inventory of polar ice cannot be readily evaluated. Since the Os isotope compositions (187Os/188Os ratio) of the terrestrial and extraterrestrial sources are distinctly different from each other, the PGE concentrations when combined with Os isotope composition have the potential to untangle contributions from these sources. Platinum group element concentration determinations in polar ice cores are highly challenging due to their extremely low concentrations (down to 10-15 g/g or fg/g). Here, a new procedure is presented that allows PGEs and Os isotope compositions to be determined from a ~50 g sample of polar ice. Decontaminated ice-melt is spiked with 101Ru, 106Pd, 190Os, 191Ir, and 198Pt and frozen at -20 °C in quartz-glass ampoules. A mixture of purified HNO3 and H2O2 is then added and the sample is heated to 300 °C at 128bar using a High Pressure Asher. This allows all spikes to be equilibrated with the sample PGEs and all Os species are oxidized to OsO4. The resulting OsO4 is extracted using distillation, purified, and measured using negative thermal ionization mass spectrometry. PGEs are then separated and purified using two stage column chromatography and their concentrations determined by isotope dilution using a triple quadruople inductively coupled plasma mass spectrometer coupled to an Apex de-solvation nebulizer. The developed method was applied to modern Greenland firn and snow. The PGE concentrations of the firn are 4.0 fg/g for Ir, 20 fg/g for Ru, 590 fg/g for Pt, 38 fg/g for Pd, and 1.3 fg/g for Os, while those of the snow are 3.0 fg/g for Ir, 53 fg/g for Ru, 360 fg/g for Pt, 32 fg/g for Pd, and 0.4 fg/g for Os, respectively. A comparison

  9. An empirical equation to estimate mineral dust concentrations from visibility observations in Northern Africa

    NASA Astrophysics Data System (ADS)

    Camino, C.; Cuevas, E.; Basart, S.; Alonso-Pérez, S.; Baldasano, J. M.; Terradellas, E.; Marticorena, B.; Rodríguez, S.; Berjón, A.

    2015-03-01

    This paper presents a new empirical equation relating horizontal visibility and PM10 dust concentrations. The new empirical equation (IZO-Eq) is derived from observations performed at the Izaña Atmospheric Observatory (IZO, 28.30°N, 16.49°W, 2367 m a.s.l., Tenerife, Spain), recorded during Saharan dust outbreaks from 2003 to 2010. A filter based on relative humidity, present-weather and aerosol optical properties is applied to identify dust events. IZO-Eq is validated in the Sahel region during the dry and wet seasons (2006-2008) using data from two PM10 monitoring stations from the African Monsoon Multidisciplinary Analysis (AMMA) International Project, and data from the nearest meteorological synoptic stations. The estimated PM10 derived from IZO-Eq is compared against that those obtained by other empirical equations and dust surface concentrations from NMMB/BSC-Dust model. IZO-Eq presents better performance than the other equations in both dry and wet seasons when compared with observed PM10 at two Sahelian sites. IZO-Eq is also able to reproduce the surface concentration variability simulated by NMMB/BSC-Dust. Above 10 km of horizontal visibility, empirical equations cannot be used to estimate PM10, since above this threshold equations estimate a nearly constant PM10 value, regardless of the visibility range. A comparison between the PM10 spatial distributions derived from visibility SYNOP observations through IZO-Eq, the modelled values from the NMMB/BSC-Dust model and aerosol optical depth (AOD) retrieved from MODIS is performed for the 2006-2008 period. The different spatial distributions present a rather good agreement among them as well as to reproduce the characteristic seasonal dust features over North Africa.

  10. Instituting a filtration/pressurization system to reduce dust concentrations in a control room at a mineral processing plant

    PubMed Central

    Noll, J.; Cecala, A.; Hummer, J.

    2016-01-01

    The National Institute for Occupational Safety and Health has observed that many control rooms and operator compartments in the U.S. mining industry do not have filtration systems capable of maintaining low dust concentrations in these areas. In this study at a mineral processing plant, to reduce respirable dust concentrations in a control room that had no cleaning system for intake air, a filtration and pressurization system originally designed for enclosed cabs was modified and installed. This system was composed of two filtering units: one to filter outside air and one to filter and recirculate the air inside the control room. Eighty-seven percent of submicrometer particles were reduced by the system under static conditions. This means that greater than 87 percent of respirable dust particles should be reduced as the particle-size distribution of respirable dust particles is greater than that of submicrometer particles, and filtration systems usually are more efficient in capturing the larger particles. A positive pressure near 0.02 inches of water gauge was produced, which is an important component of an effective system and minimizes the entry of particles, such as dust, into the room. The intake airflow was around 118 cfm, greater than the airflow suggested by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) for acceptable indoor air quality. After one year, the loading of the filter caused the airflow to decrease to 80 cfm, which still produces acceptable indoor air quality. Due to the loading of the filters, the reduction efficiency for submicrometer particles under static conditions increased to 94 percent from 87 percent. PMID:26834293

  11. Heterogeneous freezing of droplets with immersed surface modified mineral dust particles

    NASA Astrophysics Data System (ADS)

    Hartmann, Susan

    2010-05-01

    In the framework of the international measurement campaign FROST II (FReezing Of duST), the heterogeneous freezing of droplets with an immersed surface modified size-segregated mineral dust particles was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator, Stratmann et al. 2004). The following measurements were done: LACIS, CFDC (Continuous Flow thermal gradient Diffusion Chamber, Rogers (1988)) and FINCH (Fast Ice Nucleus Chamber Counter, Bundke et al (2008)) were used to analyze the immersion freezing behavior of the treated Arizona Test Dust (ATD) particles at different temperature regimes. The ability to act as IN (Ice Nucleus) in the deposition nucleation mode was quantified by the PINC (Portable Ice Nucleation Chamber) and the CFDC instrument. AMS (Aerosol Mass Spectrometers, e.g. Schneider et al. (2005)) and ATOFMS (Aerosol Time-Of-Flight Mass Spectrometer) measurements were applied to determine particle composition. The hygroscopic growth and the critical super-saturations needed for droplet activation were determined by means of an H-TDMA (Humidity-Tandem Differential Mobility Analyzer) and CCN counter (Cloud Condensation Nucleus counter, Droplet Measurement Technologies, Roberts and Nenes (2005)). The 300 nm ATD particles were chemically and physically treated by coating with sulphuric acid (H2SO4, three different coating thicknesses) and ammonium sulphate ((NH4)2SO4) or by thermal treatment with a thermodenuder operating at 250°C. The H2SO4 coating modified the particles by reacting with particle material, forming soluble sulfates and therefore changing surface properties. AMS showed free H2SO4 only for thick H2SO4 coatings. In the heated section of the thermodenuder coating materials were evaporated partly and the surface properties of the particles were additionally altered. Uncoated particles and those coated with thin coatings of H2SO4, showed almost no hygroscopic growth. Particles coated with thicker coatings of H2SO4 and of (NH4

  12. Diagnostic evaluation of the Community Earth System Model in simulating mineral dust emission with insight into large-scale dust storm mobilization in the Middle East and North Africa (MENA)

    NASA Astrophysics Data System (ADS)

    Parajuli, Sagar Prasad; Yang, Zong-Liang; Lawrence, David M.

    2016-06-01

    Large amounts of mineral dust are injected into the atmosphere during dust storms, which are common in the Middle East and North Africa (MENA) where most of the global dust hotspots are located. In this work, we present simulations of dust emission using the Community Earth System Model Version 1.2.2 (CESM 1.2.2) and evaluate how well it captures the spatio-temporal characteristics of dust emission in the MENA region with a focus on large-scale dust storm mobilization. We explicitly focus our analysis on the model's two major input parameters that affect the vertical mass flux of dust-surface winds and the soil erodibility factor. We analyze dust emissions in simulations with both prognostic CESM winds and with CESM winds that are nudged towards ERA-Interim reanalysis values. Simulations with three existing erodibility maps and a new observation-based erodibility map are also conducted. We compare the simulated results with MODIS satellite data, MACC reanalysis data, AERONET station data, and CALIPSO 3-d aerosol profile data. The dust emission simulated by CESM, when driven by nudged reanalysis winds, compares reasonably well with observations on daily to monthly time scales despite CESM being a global General Circulation Model. However, considerable bias exists around known high dust source locations in northwest/northeast Africa and over the Arabian Peninsula where recurring large-scale dust storms are common. The new observation-based erodibility map, which can represent anthropogenic dust sources that are not directly represented by existing erodibility maps, shows improved performance in terms of the simulated dust optical depth (DOD) and aerosol optical depth (AOD) compared to existing erodibility maps although the performance of different erodibility maps varies by region.

  13. Investigation of aged Asian dust particles by the combined use of quantitative ED-EPMA and ATR-FTIR imaging

    NASA Astrophysics Data System (ADS)

    Song, Y.-C.; Eom, H.-J.; Jung, H.-J.; Malek, M. A.; Kim, H. K.; Geng, H.; Ro, C.-U.

    2013-03-01

    In our previous works, it was demonstrated that the combined use of quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), which is also known as low-Z particle EPMA, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) imaging has great potential for a detailed characterization of individual aerosol particles. In this study, extensively chemically modified (aged) individual Asian dust particles collected during an Asian dust storm event on 11 November 2002 in Korea were characterized by the combined use of low-Z particle EPMA and ATR-FTIR imaging. Overall, 109 individual particles were classified into four particle types based on their morphology, elemental concentrations, and molecular species and/or functional groups of individual particles available from the two analytical techniques: Ca-containing (38%), NaNO3-containing (30%), silicate (22%), and miscellaneous particles (10%). Among the 41 Ca-containing particles, 10, 8, and 14 particles contained nitrate, sulfate, and both, respectively, whereas only two particles contained unreacted CaCO3. Airborne amorphous calcium carbonate (ACC) particles were observed in this Asian dust sample for the first time, where their IR peaks for the insufficient symmetric environment of CO32- ions of ACC were clearly differentiated from those of crystalline CaCO3. This paper also reports the first inland field observation of CaCl2 particles probably converted from CaCO3 through the reaction with HCl(g). HCl(g) was likely released from the reaction of sea salt with NOx/HNO3, as all 33 particles of marine origin contained NaNO3 (no genuine sea salt particle was encountered). Some silicate particles with minor amounts of calcium were observed to be mixed with nitrate, sulfate, and water. Among 24 silicate particles, 10 particles are mixed with water, the presence of which could facilitate atmospheric heterogeneous reactions of silicate particles including swelling minerals, such

  14. Molecular epidemiology of coal worker's pneumoconiosis: Application to risk assessment of oxidant and monokine generation by mineral dusts

    SciTech Connect

    Borm, P.J.; Meijers, J.M.; Swaen, G.M. )

    1990-01-01

    It is generally accepted that fibrotic lung diseases are mediated by macrophage-derived cytokines and growth factors. Basic research continues to find new factors involved in these disease processes to incorporate into new hypotheses. Two hypotheses implicitly generated by recent findings were tested in an epidemiologic approach among workers in coal mines. This approach is described as molecular epidemiology and is exemplified by two studies focused on different mechanistic aspects of coal workers' pneumoconiosis (CWP): antioxidants in red blood cells of miners with CWP and generation of tumor necrosis factor (TNF) by blood monocytes of miners with CWP. Most findings in the antioxidant study may merely be reflections of pulmonary inflammatory processes. Some data in the TNF study indicate, however, that TNF release is a risk factor for the development of lung fibrosis after prolonged exposure to coal mine dust.

  15. The episodic influx of tin-rich cosmic dust particles during the last ice age

    NASA Astrophysics Data System (ADS)

    LaViolette, Paul A.

    2015-12-01

    This paper presents evidence of the first detection of interstellar dust in ice age polar ice. Neutron activation analysis (NAA) results are reported for 15 elements found in dust filtered from eight samples of Camp Century Greenland ice dating from 40 to 78 kyrs BP. High concentrations of Sn, Sb, Au, Ag, Ir, and Ni were found to be present in three out of these eight samples. One compositionally anomalous dust sample from an ice core depth of 1230.5 m (age ∼49 kyrs BP, near the beginning of D/O stadial No. 13) was found to contain tin with an average weight percent of 49% as determined by energy dispersive X-ray analysis (EDS). This sample was also found to contain high concentrations of Pb with an average weight abundance of 8.4% and matching the Sn:Pb ratio observed in interstellar spectra. Dust particles in this sample generally have a platy morphology and range from submicron size up to a size as large as 120 μm, a particle consisting almost entirely of SnO2 and being the largest monomineralic extraterrestrial dust particle so far discovered. One porous aggregate tin-bearing particle was found to contain nanometer sized chondrules indicating an extraterrestrial origin. The extraterrestrial origin for the tin is also indicated by the presence of isotopic anomalies in the 114Sn, 115Sn and 117Sn isotopes. Follow up isotopic measurements of this tin-rich dust need to be performed to improve confidence in the anomalies reported here. High abundances of the low melting point elements Ag, Au, and Sb are also present in this tin-rich sample along with elevated abundances of the siderophiles Ir, Ni, Fe, and Co, the latter being present in chondritic proportions and indicating that about 9% of the dust has a C1 chondrite component. Measurements indicate that about 97% of this dust is of extraterrestrial origin with a 3% residual being composed of terrestrial windblown dust. EDS analysis of another tin-rich Camp Century ice core dust sample dating to ∼130 kyrs BP

  16. Atmospheric dry deposition of mineral dust to the Gulf of Aqaba, Red Sea: rate and trace elements.

    PubMed

    Al-Taani, Ahmed A; Rashdan, Maen; Khashashneh, Safaa

    2015-03-15

    Atmospheric dry deposition to the Gulf of Aqaba (GoA) is particularly a significant source of trace elements. Amid desert regions, the Gulf receives high fluxes of mineral dust with an average rate of 34.68 g/m(2)/year measured in 2012. Patterns of dry deposition showed seasonal fluxes with highest rates observed in summer and lowest in winter. The observed variations were attributed to wind direction, timing of deposition and sources of dust. The average dry fluxes of Al, Fe, Mn, Cr, Cd, Cu, Pb and Zn were 551, 440, 10.29, 1.42, 0.04, 0.68, 1.42 and 4.02 mg/m(2)/year, respectively. While the dry deposition fluxes were enriched in Cd, Cu, Pb and Zn indicating their dominant anthropogenic sources, they appeared to be less influenced compared to the neighboring Mediterranean area and other industrial countries, but were similar to or slightly higher than those in remote areas. The enrichment values for Fe and Mn were low, consistent with their crustal origin. The fluxes of all elements suggested the impacts of both crustal (due to climate change) and anthropogenic sources became stronger in this region. The Sahara dust was probably a minor contributor to dry deposition in the GoA.

  17. The adsorption of fungal ice-nucleating proteins on mineral dusts: a terrestrial reservoir of atmospheric ice-nucleating particles

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Daniel; Murray, Benjamin J.; Ross, James; Webb, Michael E.

    2016-04-01

    The occurrence of ice-nucleating particles (INPs) in our atmosphere has a profound impact on the properties and lifetime of supercooled clouds. However, the identities, sources and abundances of airborne particles capable of efficiently nucleating ice at relatively low supercoolings (T > -15 °C) remain enigmatic. Recently, several studies have suggested that unidentified biogenic residues in soil dusts are likely to be an important source of these efficient atmospheric INPs. While it has been shown that cell-free proteins produced by common soil-borne fungi are exceptional INPs, whether these fungi are a source of ice-nucleating biogenic residues in soils has yet to be shown. In particular, it is unclear whether upon adsorption to soil mineral particles, the activity of fungal ice-nucleating proteins is retained or is reduced, as observed for other soil enzymes. Here we show that proteins from a common soil fungus (Fusarium avenaceum) do in fact preferentially bind to and impart their ice-nucleating properties to the common clay mineral kaolinite. The ice-nucleating activity of the proteinaceous INPs is found to be unaffected by adsorption to the clay, and once bound the proteins do not readily desorb, retaining much of their activity even after multiple washings with pure water. The atmospheric implications of the finding that nanoscale fungal INPs can effectively determine the nucleating abilities of lofted soil dusts are discussed.

  18. Investigation of aged aerosols in size-resolved Asian dust storm particles transported from Beijing, China to Incheon, Korea using low-Z particle EPMA

    NASA Astrophysics Data System (ADS)

    Geng, H.; Hwang, H. J.; Liu, X.; Dong, S.; Ro, C.-U.

    2013-10-01

    This is the first study of Asian dust storm (ADS) particles collected in Beijing, China and Incheon, Korea during the same spring ADS event. Using a seven-stage May impactor and a quantitative electron probe X-ray microanalysis (ED-EPMA, also known as low-Z particle EPMA), we examined the composition and morphology of 4200 aerosol particles at stages 1-6 (with a size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent aerodynamic diameter, respectively) collected during an ADS event on 28-29 April 2005. The results showed that there were large differences in the chemical compositions between particles in sample S1 collected in Beijing immediately after the peak time of the ADS and in samples S2 and S3, which were collected in Incheon approximately 5 h and 24 h later, respectively. In sample S1, mineral dust particles accounted for more than 88% in relative number abundance at stages 1-5, and organic carbon (OC) and reacted NaCl-containing particles accounted for 24% and 32%, respectively, at stage 6. On the other hand, in samples S2 and S3, in addition to approximately 60% mineral dust, many sea salt particles reacted with airborne SO2 and NOx, often mixed with mineral dust, were encountered at stages 1-5, and (C, N, O, S)-rich particles (likely a mixture of water-soluble organic carbon with (NH4)2SO4 and NH4NO3) and K-containing particles were abundantly observed at stage 6. This suggests that the secondary aerosols and the internal mixture of mineral dust with sea spray aerosol increased when the ADS particles passed over the Yellow Sea. In the reacted or aged mineral dust and sea salt particles, nitrate-containing and both nitrate- and sulfate-containing species vastly outnumbered the sulfate-containing species, implying that ambient nitrogen oxides had a greater influence on the atmospheric particles during the ADS episode than SO2. In addition to partially- or totally-reacted CaCO3, reacted or aged Mg-containing aluminosilicates (likely including amesite

  19. Investigating the Heterogeneous Interaction of VOCs with Natural Atmospheric Particles: Adsorption of Limonene and Toluene on Saharan Mineral Dusts.

    PubMed

    Romanías, Manolis N; Ourrad, Habib; Thévenet, Frédéric; Riffault, Véronique

    2016-03-01

    The heterogeneous interaction of limonene and toluene with Saharan dusts was investigated under dark conditions, pressure of 1 atm, and temperature 293 K. The mineral dust samples were collected from six different regions along the Sahara desert, extending from Tunisia to the western Atlantic coastal areas of Morocco, and experiments were carried out with the smallest sieved fractions, that is, inferior to 100 μm. N2 sorption measurements, granulometric analysis, and X-ray fluorescence and diffraction (XRF and XRD) measurements were conducted to determine the physicochemical properties of the particles. The chemical characterization showed that dust originating from mideastern Sahara has a significantly higher SiO2 content (∼ 82%) than dust collected from the western coastal regions where the SiO2 relative abundance was ∼ 50%. A novel experimental setup combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), selected-ion flow-tube mass spectrometry (SIFT-MS), and long path transmission Fourier transform infrared spectroscopy (FTIR) allowed us to follow both the adsorbed and gas phases. The kinetic adsorption/desorption measurements were performed using purified dry air as bath gas, exposing each dust surface to 10 ppm of the selective volatile organic compound (VOC). The adsorption of limonene was independent of the SiO2 content, given the experimental uncertainties, and the coverage measurements ranged between (10 and 18) × 10(13) molecules cm(-2). Experimental results suggest that other metal oxides that could possibly influence dust acidity may enhance the adsorption of limonene. On the contrary, in the case of toluene, the adsorption capacities of the Saharan samples increased with decreasing SiO2 content; however, the coverage measurements were significantly lower than those of limonene and ranged between (2 and 12) × 10(13) molecules cm(-2). Flushing the surface with purified dry air showed that VOC desorption is not a

  20. Investigating the Heterogeneous Interaction of VOCs with Natural Atmospheric Particles: Adsorption of Limonene and Toluene on Saharan Mineral Dusts.

    PubMed

    Romanías, Manolis N; Ourrad, Habib; Thévenet, Frédéric; Riffault, Véronique

    2016-03-01

    The heterogeneous interaction of limonene and toluene with Saharan dusts was investigated under dark conditions, pressure of 1 atm, and temperature 293 K. The mineral dust samples were collected from six different regions along the Sahara desert, extending from Tunisia to the western Atlantic coastal areas of Morocco, and experiments were carried out with the smallest sieved fractions, that is, inferior to 100 μm. N2 sorption measurements, granulometric analysis, and X-ray fluorescence and diffraction (XRF and XRD) measurements were conducted to determine the physicochemical properties of the particles. The chemical characterization showed that dust originating from mideastern Sahara has a significantly higher SiO2 content (∼ 82%) than dust collected from the western coastal regions where the SiO2 relative abundance was ∼ 50%. A novel experimental setup combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), selected-ion flow-tube mass spectrometry (SIFT-MS), and long path transmission Fourier transform infrared spectroscopy (FTIR) allowed us to follow both the adsorbed and gas phases. The kinetic adsorption/desorption measurements were performed using purified dry air as bath gas, exposing each dust surface to 10 ppm of the selective volatile organic compound (VOC). The adsorption of limonene was independent of the SiO2 content, given the experimental uncertainties, and the coverage measurements ranged between (10 and 18) × 10(13) molecules cm(-2). Experimental results suggest that other metal oxides that could possibly influence dust acidity may enhance the adsorption of limonene. On the contrary, in the case of toluene, the adsorption capacities of the Saharan samples increased with decreasing SiO2 content; however, the coverage measurements were significantly lower than those of limonene and ranged between (2 and 12) × 10(13) molecules cm(-2). Flushing the surface with purified dry air showed that VOC desorption is not a

  1. Effects of Saharan Mineral Dust Aerosols on the Dynamics of an Idealized African Easterly Jet-African Easterly Wave System over North Africa

    NASA Astrophysics Data System (ADS)

    Grogan, Dustin Francis Phillip

    The central objective of this work is to examine the direct radiative effects of Saharan mineral dust aerosols on the dynamics of African easterly waves (AEWs) and the African easterly jet (AEJ). Achieving this objective is built around two tasks that use the Weather Research and Forecasting (WRF) model coupled to an online dust model (WRF-dust model). The first task (Chapter 2) examines the linear dynamics of AEWs; the second task (Chapter 3) examines the nonlinear evolution of AEWs and their interactions with the AEJ. In Chapter 2, the direct radiative effects of dust on the linear dynamics of AEWs are examined analytically and numerically. The analytical analysis combines the thermodynamic equation with a dust continuity equation to form an expression for the generation of eddy available potential energy (APE) by the dust field. The generation of eddy APE is a function of the transmissivity and spatial gradients of the dust, which are modulated by the Doppler-shifted frequency. The expression predicts that for a fixed dust distribution, the wave response will be largest in regions where the dust gradients are maximized and the Doppler-shifted frequency vanishes. The numerical analysis calculates the linear dynamics of AEWs using zonally averaged basic states for wind, temperature and dust consistent with summertime conditions over North Africa. For the fastest growing AEW, the dust increases the growth rate from ~15% to 90% for aerosol optical depths ranging from tau=1.0 to tau=2.5. A local energetics analysis shows that for tau=1.0, the dust increases the maximum barotropic and baroclinic energy conversions by ~50% and ~100%, respectively. The maxima in the generation of APE and conversions of energy are co-located and occur where the meridional dust gradient is maximized near the critical layer, i.e., where the Doppler-shifted frequency is small, in agreement with the prediction from the analytical analysis. In Chapter 3, the direct radiative effects of dust

  2. Laboratory measurements of contact nucleation by mineral dusts, bacteria, and soluble salts

    NASA Astrophysics Data System (ADS)

    Niehaus, Joseph

    We present results from experiments that emulate atmospheric ice nucleation by aerosols. We have refined experimental techniques to improve measurements of ice forming nuclei in the contact mode. Our results show that atmospherically relevant dusts such as kaolinite, feldspar, rhyolitic ash, and Arizona Test Dust have efficiencies in the contact mode that are higher than the immersion mode. Experiments with bacteria show that biological material has the potential to contribute significantly to ice concentrations, but has large variability. By choosing a soluble compound as an ice nucleus, we are able to place bounds on the timescale for contact freezing and estimate the nucleation time from impact to be 10--9 seconds. Finally, we conclude that the contact mode can increase nucleation rates in two ways: by the creation of a triple-phase line with an insoluble nucleus, or by the collision event.

  3. Composition, size distribution, optical properties and radiative effects of re-suspended local mineral dust of Rome area by individual-particle microanalysis and radiative transfer modelling

    NASA Astrophysics Data System (ADS)

    Pietrodangelo, A.; Salzano, R.; Bassani, C.; Pareti, S.; Perrino, C.

    2015-05-01

    New information on the PM10 mineral dust from site-specific (Rome area, Latium) outcropped rocks, and on the microphysics, optical properties and radiative effects of mineral dust at local level were gained in this work. A multi-disciplinary approach was used, based on individual-particle scanning electron microscopy with X-ray energy-dispersive microanalysis (SEM XEDS), X-ray diffraction (XRD) analysis of dust, size distribution of mineral particles, and radiative transfer modelling (RTM).The mineral composition of Rome lithogenic PM10 varies between an end-member dominated by silicate minerals and one exclusively composed of calcite. The first is obtained from volcanic lithotypes, the second from travertine or limestones; lithogenic PM10 with intermediate composition derives mainly from siliciclastic rocks or marlstones of Rome area. Size and mineral species of PM10 particles of silicate-dominated dust types are tuned mainly by weathering and, to lesser extent, by debris formation or crystallization; chemical precipitation of CaCO3 plays a major role in calcite-dominated types. These differences are evidenced by the diversity of volume distributions, within either dust types, or mineral species. Further differences are observed between volume distributions of calcite from travertine (natural source) and from road dust (anthropic source), specifically on the width, shape and enrichment of the fine fraction (unimodal at 5 μm a.d. for travertine, bimodal at 3.8 and 1.8 μm a.d. for road dust). Log-normal probability density functions of volcanics and travertine dusts affect differently the single scattering albedo (SSA) and the asymmetry parameter (g) in the VISible and Near Infrared (NIR) regions, depending also on the absorbing/non-absorbing character of volcanics and travertine, respectively. The downward component of the BOA solar irradiance simulated by RTM for a volcanics-rich or travertine-rich atmosphere shows that volcanics contribution to the solar

  4. A transmission electron microscopy study of mineralization in age-induced transparent dentin.

    PubMed

    Porter, Alexandra E; Nalla, Ravi K; Minor, Andrew; Jinschek, Joerg R; Kisielowski, Christian; Radmilovic, Velimir; Kinney, John H; Tomsia, Antoni P; Ritchie, R O

    2005-12-01

    It is known that fractures are more likely to occur in altered teeth, particularly following restoration or endodontic repair; consequently, it is important to understand the structure of altered forms of dentin, the most abundant tissue in the human tooth, in order to better define the increased propensity for such fractures. Transparent (or sclerotic) dentin, wherein the dentinal tubules become occluded with mineral as a natural progressive consequence of aging, is one such altered form. In the present study, high-resolution transmission electron microscopy is used to investigate the effect of aging on the mineral phase of dentin. Such studies revealed that the intertubular mineral crystallites were smaller in transparent dentin, and that the intratubular mineral (larger crystals deposited within the tubules) was chemically similar to the surrounding intertubular mineral. Exit-wave reconstructed lattice-plane images suggested that the intratubular mineral had nanometer-size grains. These observations support a "dissolution and reprecipitation" mechanism for the formation of transparent dentin.

  5. ANALYSIS OF AGED IN-HOME CARPETING TO DETERMINE THE DISTRIBUTION OF PESTICIDE RESIDUES BETWEEN DUST, CARPET, AND PAD COMPARTMENTS

    EPA Science Inventory

    This report presents results of a study to determine the distribution of pesticides, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) between dust and carpet components in aged carpeting. Carpeting in eight homes in the Research Triangle Area, which...

  6. Coordinated Analyses of Mineral-organic Matter Associations in Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K.; Herzog, G. F.; Smith, T.; Keller, L. P.; Flynn, G. J.; Khodja, H.; Taylor, S.; Wirick, S.; Messenger, S.

    2012-01-01

    Little is known about the timing and processes involved in the incorporation of organic matter with inorganic materials in early Solar System bodies. Recently, X-ray absorption near-edge spectroscopy (XANES) studies showed carbon-rich rims surrounding individual mineral grains in anhydrous IDPs [1,2]. These carbonaceous rims are believed to have formed prior to parent body formation and likely served to bond mineral grains during accretion into larger aggregates. We are exploring the nature of these carbonaceous rims through coordinated analyses of their chemistry, mineralogy, spectroscopy and isotopic characteristics. Here we report our preliminary mineralogical observations.

  7. [Hygienic regulation of dust of magnesium-silicate minerals and fireproof materials].

    PubMed

    Kislitsina, N S; Privalova, L I; Sharapova, N E

    1993-01-01

    Chronic experiments on rats showed that the dust of silicomagnesian refractory and dunite (a raw material for refractory production) extracted in Kytlym differ insignificantly in fibrogenic activity, but rank below the quartzite extracted in Pervouralsk (MAC-1 mg/cu m). The short study analyzing the cytologic changes of bronchoalveolar lavage determined the cytotoxicity of silicomagnesian refractory and 4 other types of dunite. The estimated cytotoxicity also ranked below that of quartzite from Pervouralsk. The MAC equal to 4 mg/cu m was suggested for the group of aerosols produced by dunite and silicomagnesian refractories. These aerosols are assigned to the 3rd jeopardy class and possess basically fibrogenic activity.

  8. [Hygienic regulation of dust of magnesium-silicate minerals and fireproof materials].

    PubMed

    Kislitsina, N S; Privalova, L I; Sharapova, N E

    1993-01-01

    Chronic experiments on rats showed that the dust of silicomagnesian refractory and dunite (a raw material for refractory production) extracted in Kytlym differ insignificantly in fibrogenic activity, but rank below the quartzite extracted in Pervouralsk (MAC-1 mg/cu m). The short study analyzing the cytologic changes of bronchoalveolar lavage determined the cytotoxicity of silicomagnesian refractory and 4 other types of dunite. The estimated cytotoxicity also ranked below that of quartzite from Pervouralsk. The MAC equal to 4 mg/cu m was suggested for the group of aerosols produced by dunite and silicomagnesian refractories. These aerosols are assigned to the 3rd jeopardy class and possess basically fibrogenic activity. PMID:7921832

  9. Effects of Palagonitic Dust Coatings on Thermal Emission Spectra of Rocks and Minerals: Implications for Mineralogical Characterization of the Martian Surface by MGS-TES

    NASA Technical Reports Server (NTRS)

    Graff, T. G.; Morris, R.; Christensen, P.

    2001-01-01

    Thermal emission measurements on dust-coated rocks and minerals show that a 300 5m thick layer is required to mask emission from the substrate and that non-linear effects are present. Additional information is contained in the original extended abstract.

  10. Effects of Palagonitic Dust Coatings on Visible, Near-IR, and Mossbauer Spectra of Rocks and Minerals: Implication for Mineralogical Remote Sensing of Mars

    NASA Technical Reports Server (NTRS)

    Morris, R.; Graff, T. G.; Shelfer, T. D.; Bell, J. F., III

    2001-01-01

    Visible, near-IR, and Mossbauer measurements on dust coated rocks and minerals show that a 300 5m thick layer is required to obscure the substrate for VNIR measurements and that a greater than 2000-micron-thick layer is required to obscure the substrate for Mossbauer measurements. Additional information is contained in the original extended abstract.

  11. Observation of the simultaneous transport of Asian mineral dust aerosols with anthropogenic pollutants using a POPC during a long-lasting dust event in late spring 2014

    NASA Astrophysics Data System (ADS)

    Pan, Xiaole; Uno, Itsushi; Hara, Yukari; Kuribayashi, Masatoshi; Kobayashi, Hiroshi; Sugimoto, Nobuo; Yamamoto, Shigekazu; Shimohara, Takaaki; Wang, Zifa

    2015-03-01

    We observed a long-lasting dust event from 25 May to 2 June 2014, using a polarization optical particle counter (POPC). The transport of dust plumes over East Asia was verified on the basis of observations of Moderate Resolution Imaging Spectroradiometer, a lidar network, and surface synoptic observation stations. Mixing of dust and anthropogenic pollutants was investigated according to the variation in the depolarization ratio as a function of particle size. The nonsphericity of dust particles varied due to the impact of anthropogenic pollutants on their pathway. In the coarse mode, dust particles always had a clear nonspherical configuration, although large amounts of nitrate were also present. Supermicron particles are occasionally present in a spherical configuration, possibly due to the complex mixing of natural dust and anthropogenic particles. Statistically, ~64% of the total nitrate mass was deemed to be transported from outside of Japan due to a trapping effect in the dust plume.

  12. Laboratory-generated mixtures of mineral dust particles with biological substances: characterization of the particle mixing state and immersion freezing behavior

    NASA Astrophysics Data System (ADS)

    Augustin-Bauditz, Stefanie; Wex, Heike; Denjean, Cyrielle; Hartmann, Susan; Schneider, Johannes; Schmidt, Susann; Ebert, Martin; Stratmann, Frank

    2016-05-01

    Biological particles such as bacteria, fungal spores or pollen are known to be efficient ice nucleating particles. Their ability to nucleate ice is due to ice nucleation active macromolecules (INMs). It has been suggested that these INMs maintain their nucleating ability even when they are separated from their original carriers. This opens the possibility of an accumulation of such INMs in soils, resulting in an internal mixture of mineral dust and INMs. If particles from such soils which contain biological INMs are then dispersed into the atmosphere due to wind erosion or agricultural processes, they could induce ice nucleation at temperatures typical for biological substances, i.e., above -20 up to almost 0 °C, while they might be characterized as mineral dust particles due to a possibly low content of biological material. We conducted a study within the research unit INUIT (Ice Nucleation research UnIT), where we investigated the ice nucleation behavior of mineral dust particles internally mixed with INM. Specifically, we mixed a pure mineral dust sample (illite-NX) with ice active biological material (birch pollen washing water) and quantified the immersion freezing behavior of the resulting particles utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS). A very important topic concerning the investigations presented here as well as for atmospheric application is the characterization of the mixing state of aerosol particles. In the present study we used different methods like single-particle aerosol mass spectrometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), and a Volatility-Hygroscopicity Tandem Differential Mobility Analyser (VH-TDMA) to investigate the mixing state of our generated aerosol. Not all applied methods performed similarly well in detecting small amounts of biological material on the mineral dust particles. Measuring the hygroscopicity/volatility of the mixed particles with the VH-TDMA was the most

  13. Analysis of In-Situ of Ozone Measurements in Saharan Mineral Dust during AEROSE Cruises

    NASA Astrophysics Data System (ADS)

    Roper, E. D.; Morris, V. R.; Nalli, N. R.; Joseph, E.

    2012-12-01

    The trans-Atlantic Aerosol and Oceanographic Science Expeditions (AEROSE) are a series of experiments that began in 2004 and take place in the tropical Atlantic Ocean. AEROSE collects a unique set of critical measurements to characterize the microphysical and chemical evolution of the Saharan dust aerosols during long-range transport. Continuous in-situ surface level measurements over the tropical Atlantic allows for accurate determination of lower tropospheric ozone concentrations, and its effects on the regional environment and climate that may be used to validate satellite observations. Ozone is instrumental in regulating the atmosphere's oxidizing capacity and can influence background levels of trace chemical species which affect the composition of the atmosphere and create climatic variations. Several studies have shown that ozone concentrations diminish with increased loading of dust particles from the Sahara. Current theories indicate that decomposition of ozone may be due to NOx titrations, decreased radiation, photocatalysis, interactions with organics, or heterogeneous reactions. In effort to understand the response of marine boundary layer ozone with coarse aerosols, analyses of ozone concentrations and aerosol correlations found in dusty Saharan air masses from various cruises will be presented.

  14. Mineral dust and cell recovery from the bronchoalveolar lavage of healthy Vermont granite workers.

    PubMed

    Christman, J W; Emerson, R J; Graham, W G; Davis, G S

    1985-08-01

    We characterized the bronchoalveolar lavage (BAL) from healthy Vermont granite workers to investigate the pulmonary response to a chronic exposure to an injurious agent. Nine granite workers with 4 to 36 yr of employment in the industry and 27 unexposed volunteers were normal by history, physical examination, electrocardiogram, blood count, spirometry, and chest radiograph. Lavage cell recovery and percent neutrophils were not different. Lymphocyte recovery in BAL was increased in the granite-exposed population. Granite dust was present within the majority of alveolar macrophages from granite workers compared with those from control subjects, as determined by polarizing light microscopy and confirmed by scanning electron microscopy with X-ray energy spectrometry. There were no differences in phagocytic function or viability of macrophages from granite workers compared with those from unexposed volunteers. We conclude that in exposed populations, granite dust can be detected and semiquantitated in lavage specimens within the alveolar macrophages, macrophage function is preserved, and the response to this exposure involves an influx of lymphocytes.

  15. Transport of mineral dust derived from airborne wind lidar measurements during SALTRACE

    NASA Astrophysics Data System (ADS)

    Chouza, Fernando; Reitebuch, Oliver; Groß, Silke; Rahm, Stephan; Freudenthaler, Volker; Toledano, Carlos; Weinzierl, Bernadett

    2015-04-01

    During the SALTRACE field experiment conducted between the 10 of June and the 15 of July 2013, the transport and properties of Saharan dust were characterized by a 2-µm Doppler wind lidar (DWL) deployed on the DLR Falcon 20 research aircraft. Unlike aerosol lidars, the DLW is able to simultaneously measure wind fields and -by means of an adequate calibration- aerosol optical properties, which is more adequate for aerosol transport studies. The retrieved horizontal and vertical wind speed provide a direct observation of dust long range transport mechanisms across the Atlantic (e.g. by the African easterly jet) from Western Africa to the Caribbean. Vertical wind observations revealed the structure of island induced lee waves in the Cape Verde and Barbados regions. A novel method for the calibration of DWLs based on simultaneous measurements with a ground-based aerosol lidar and sun photometer was developed. After being calibrated, the system is able to retrieve quantitative aerosol backscatter and extinction coefficients, which is usually not obtained from coherent lidars. Results from the validation with a ground-based aerosol lidar in Barbados and the CALIPSO satellite instrument will be discussed.

  16. The impact of glacier retreat from the Ross Sea on local climate: Characterization of mineral dust in the Taylor Dome ice core, East Antarctica

    NASA Astrophysics Data System (ADS)

    Aarons, S. M.; Aciego, S. M.; Gabrielli, P.; Delmonte, B.; Koornneef, J. M.; Wegner, A.; Blakowski, M. A.

    2016-06-01

    Recent declines in ice shelf and sea ice extent experienced in polar regions highlight the importance of evaluating variations in local weather patterns in response to climate change. Airborne mineral particles (dust) transported through the atmosphere and deposited on ice sheets and glaciers in Antarctica and Greenland can provide a robust set of tools for resolving the evolution of climatic systems through time. Here we present the first high time resolution radiogenic isotope (strontium and neodymium) data for Holocene dust in a coastal East Antarctic ice core, accompanied by rare earth element composition, dust concentration, and particle size distribution during the last deglaciation. We aim to use these combined ice core data to determine dust provenance, with variations indicative of shifts in either dust production, sources, and/or transport pathways. We analyzed a series of 17 samples from the Taylor Dome (77°47‧47″S, 158°43‧26″E) ice core, 113-391 m in depth from 1.1-31.4 ka. Radiogenic isotopic and rare earth element compositions of dust during the last glacial period are in good agreement with previously measured East Antarctic ice core dust records. In contrast, the Holocene dust dataset displays a broad range in isotopic and rare earth element compositions, suggesting a shift from long-range transported dust to a more variable, local input that may be linked to the retreat of the Ross Ice Shelf during the last deglaciation. Observed changes in the dust cycle inferred from a coastal East Antarctic ice core can thus be used to infer an evolving local climate.

  17. Synergistic formation of sulfate and ammonium resulting from reaction between SO2 and NH3 on typical mineral dust.

    PubMed

    Yang, Weiwei; He, Hong; Ma, Qingxin; Ma, Jinzhu; Liu, Yongchun; Liu, Pengfei; Mu, Yujing

    2016-01-14

    The heterogeneous reactions of SO2 and NH3 on typical mineral oxides were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). A new sulfate formation pathway was proposed where NH3 accelerated the formation of sulfate species. The results revealed that surface hydroxyls and oxygen played principal roles in the conversion of SO2 to sulfate. It was proposed that NH3 adsorbed onto Lewis acid sites, and hydroxyls and water molecules adsorbed on the surfaces of mineral dust. The enhancement of surface Lewis basicity by NH3 induced more SO2 molecules to adsorb on the surface, which were further oxidized to sulfate by interacting with surface hydroxyls and oxygen atoms. The formation of sulfate, in turn, contributed to the adsorption of NH3, mainly as NH4(+) due to enhanced Brønsted acid sites. The IC results showed that the synergistic effect between SO2 and NH3 was more significant on acidic oxides like γ-Al2O3 and α-Fe2O3 compared to basic oxides like MgO.

  18. Pulmonary epithelial response in the rat lung to instilled Montserrat respirable dusts and their major mineral components

    PubMed Central

    Housley, D; Berube, K; Jones, T; Anderson, S; Pooley, F; Richards, R

    2002-01-01

    Background: The Soufriere Hills, a stratovolcano on Montserrat, started erupting in July 1995, producing volcanic ash, both from dome collapse pyroclastic flows and phreatic explosions. The eruptions/ash resuspension result in high concentrations of suspended particulate matter in the atmosphere, which includes cristobalite, a mineral implicated in respiratory disorders. Aims: To conduct toxicological studies on characterised samples of ash, together with major components of the dust mixture (anorthite, cristobalite), and a bioreactive mineral control (DQ12 quartz). Methods: Rats were challenged with a single mass (1 mg) dose of particles via intratracheal instillation and groups sacrificed at one, three, and nine weeks. Acute bioreactivity of the particles was assessed by increases in lung permeability and inflammation, changes in epithelial cell markers, and increase in the size of bronchothoracic lymph nodes. Results: Data indicated that respirable ash derived from pyroclastic flows (20.1% cristobalite) or phreatic explosion (8.6% cristobalite) had minimal bioreactivity in the lung. Anorthite showed low bioreactivity, in contrast to pure cristobalite, which showed progressive increases in lung damage. Conclusion: Results suggests that either the percentage mass of cristobalite particles present in Montserrat ash was not sufficient as a catalyst in the lung environment, or its surface reactivity was masked by the non-reactive volcanic glass components during the process of ash formation. PMID:12107295

  19. Age-related differences in the bone mineralization pattern of rats following exercise

    SciTech Connect

    McDonald, R.; Hegenauer, J.; Saltman, P.

    1986-07-01

    The effect of 12 weeks of treadmill exercise on the mineralization of trabecular and cortical bone was studied in rats 7, 14, and 19 months of age. Bone mineralization was evaluated by measuring concentrations of Ca, Mg, and hydroxyproline as well as uptake of 45Ca concentration in the femur, humerus, rib and calvaria. The 7- and 14-month-old rats increased mineralization in those cortical bones directly involved in exercise. The 19-month animal responded to exercise by increasing mineralization in all bones examined, including the nonweight bearing trabecular calvaria and cortical rib. From these data, it is apparent that the older animals undergo a total skeletal mineralization in response to exercise compared with local adaptation in the younger animal. Further, we provide evidence to support the use of the rat as a model in which to study mammalian bone physiology during the aging process.

  20. Kinetics of deposition and clearance of inhaled mineral dusts during chronic exposure.

    PubMed Central

    Vincent, J H; Johnston, A M; Jones, A D; Bolton, R E; Addison, J

    1985-01-01

    New inhalation studies have been carried out with rats exposed to UICC (Union International Contre le Cancer) amosite asbestos, with the main aim of further elucidating the factors the influence the accumulation of dust in the lung during prolonged chronic exposure. The results show that, for exposure times beyond a few weeks, the lung burden rises linearly and does not level off as predicted by simple models based on ideas taken from the 1966 report of the Task Group on Lung Dynamics. Furthermore, the lung burden is found to scale directly in proportion to the exposure concentration in a way that seems to contradict the overload hypothesis stated earlier. Nevertheless, the general pattern exhibited by our results for asbestos is markedly similar to that found elsewhere for rats inhaling diesel fume, leading to the suggestion that it is general (and not specific to fibrous dust); and the hypothesis that, whereas overload of clearance can take place at high lung burdens after exposure has ceased, it is cancelled by the sustained stimulus to clearance mechanisms provided by the continuous challenge of chronic exposure. The linearity of the increase in lung burden is explained in terms of a kinetic model involving sequestration of some inhaled material to parts of the lung where it is difficult to clear. The particular sequestration model favoured is one where, the longer a particle remains in the lung without being cleared, the more likely it will be sequestrated (and therefore less likely cleared). It is believed that such ideas may eventually be useful in forming exposure-dose relations for epidemiology. PMID:2864076

  1. Nitrogen mineralization from anaerobically digested centrifuge cake and aged air-dried biosolids.

    PubMed

    Kumar, Kuldip; Hundal, Lakhwinder S; Cox, Albert E; Granato, Thomas

    2014-09-01

    This study was conducted to estimate nitrogen (N) mineralization of anaerobically digested centrifuge cake from the Stickney Water Reclamation Plant (SWRP) and Calumet Water Reclamation Plant (CWRP), lagoon-aged air-dried biosolids from the CWRP, and Milorganite at three rates of application (0, 12.5 and 25 Mg ha(-1)). The N mineralized varied among biosolids as follows: Milorganite (44%) > SWRP centrifuge cake (35%) > CWRP centrifuge cake (31%) > aged air-dried (13%). The N mineralized in the SWRP cake (32%) and CWRP aged air-dried biosolids (12%) determined from the 15N study were in agreement with the first study. The N mineralization value for centrifuge cake biosolids observed in our study is higher than the value given in the Part 503 rule and Illinois Part 391 guidelines. These results will be used to fine-tune biosolids application rate to match crop N demand without compromising yield while minimizing any adverse effect on the environment. PMID:25327023

  2. Nitrogen mineralization from anaerobically digested centrifuge cake and aged air-dried biosolids.

    PubMed

    Kumar, Kuldip; Hundal, Lakhwinder S; Cox, Albert E; Granato, Thomas

    2014-09-01

    This study was conducted to estimate nitrogen (N) mineralization of anaerobically digested centrifuge cake from the Stickney Water Reclamation Plant (SWRP) and Calumet Water Reclamation Plant (CWRP), lagoon-aged air-dried biosolids from the CWRP, and Milorganite at three rates of application (0, 12.5 and 25 Mg ha(-1)). The N mineralized varied among biosolids as follows: Milorganite (44%) > SWRP centrifuge cake (35%) > CWRP centrifuge cake (31%) > aged air-dried (13%). The N mineralized in the SWRP cake (32%) and CWRP aged air-dried biosolids (12%) determined from the 15N study were in agreement with the first study. The N mineralization value for centrifuge cake biosolids observed in our study is higher than the value given in the Part 503 rule and Illinois Part 391 guidelines. These results will be used to fine-tune biosolids application rate to match crop N demand without compromising yield while minimizing any adverse effect on the environment.

  3. Incidence and progression of pneumoconiosis over nine years in US coal miners: II. Relationship with dust exposure and other potential causative factors

    SciTech Connect

    Attfield, M.; Reger, R.; Glenn, R.

    1984-01-01

    Examination of the incidence and progression of pneumoconiosis over 9 years in 1,261 nationally distributed US coal miners has been undertaken in relationship to potential causative factors. Use has been made of a large body of data on dust levels collected by the Mine Safety and Health Administration principally for compliance purposes. Reported dust levels were low and generally under the current 2 mg/m3 standard. No link between dust level and disease progression could be detected. Some evidence was seen that radiological change was related to dust exposures prior to the study in both coal and noncoal mines, and thus experienced before the current dust standards were mandated. Neither migration of miners nor mining method appeared to be associated with disease incidence or progression. None of these findings can be taken as final, as the period of study is short and the number of cases of pneumoconiosis few. Further study is under way to obtain more reliable information over a longer period of follow-up.

  4. Heterogeneous freezing of droplets with immersed mineral dust particles - measurements and parameterization

    NASA Astrophysics Data System (ADS)

    Niedermeier, D.; Hartmann, S.; Shaw, R. A.; Covert, D.; Mentel, T. F.; Schneider, J.; Poulain, L.; Reitz, P.; Spindler, C.; Clauss, T.; Kiselev, A.; Hallbauer, E.; Wex, H.; Mildenberger, K.; Stratmann, F.

    2010-04-01

    During the measurement campaign FROST (FReezing Of duST), LACIS (Leipzig Aerosol Cloud Interaction Simulator) was used to investigate the immersion freezing behavior of size selected, coated and uncoated Arizona Test Dust (ATD) particles with a mobility diameter of 300 nm. Particles were coated with succinic acid (C4H6O4), sulfuric acid (H2SO4) and ammonium sulfate ((NH4)2SO4). Ice fractions at mixed-phase cloud temperatures ranging from 233.15 K to 239.15 K (±0.60 K) were determined for all types of particles. In this temperature range, pure ATD particles and those coated with C4H6O4 or small amounts of H2SO4 were found to be the most efficient ice nuclei (IN). ATD particles coated with (NH4)2SO4 were the most inefficient IN. Since the supercooled droplets were highly diluted before freezing occurred, a freezing point suppression due to the soluble material on the particles (and therefore in the droplets) cannot explain this observation. Therefore, it is reasonable to assume that the coatings lead to particle surface alterations which cause the differences in the IN abilities. Two different theoretical approaches based on the stochastic and the singular hypotheses were applied to clarify and parameterize the freezing behavior of the particles investigated. Both approaches describe the experimentally determined results, yielding parameters that can subsequently be used to compare our results to those from other studies. However, we cannot clarify at the current state which of the two approaches correctly describes the investigated immersion freezing process. But both approaches confirm the assumption that the coatings lead to particle surface modifications lowering the nucleation efficiency. The stochastic approach interprets the reduction in nucleation rate from coating as primarily due to an increase in the thermodynamic barrier for ice formation (i.e., changes in interfacial free energies). The singular approach interprets the reduction as resulting from a

  5. Impaired Vestibular Function and Low Bone Mineral Density: Data from the Baltimore Longitudinal Study of Aging.

    PubMed

    Bigelow, Robin T; Semenov, Yevgeniy R; Anson, Eric; du Lac, Sascha; Ferrucci, Luigi; Agrawal, Yuri

    2016-10-01

    Animal studies have demonstrated that experimentally induced vestibular ablation leads to a decrease in bone mineral density, through mechanisms mediated by the sympathetic nervous system. Loss of bone mineral density is a common and potentially morbid condition that occurs with aging, and we sought to investigate whether vestibular loss is associated with low bone mineral density in older adults. We evaluated this question in a cross-sectional analysis of data from the Baltimore Longitudinal Study of Aging (BLSA), a large, prospective cohort study managed by the National Institute on Aging (N = 389). Vestibular function was assessed with cervical vestibular evoked myogenic potentials (cVEMPs), a measure of saccular function. Bone mineral density was assessed using dual-energy X-ray absorptiometry (DEXA). In two-way t test analysis, we observed that individuals with reduced vestibular physiologic function had significantly lower bone mineral density. In adjusted multivariate linear regression analyses, we observed that older individuals with reduced vestibular physiologic function had significantly lower bone mineral density, specifically in weight-bearing hip and lower extremity bones. These results suggest that the vestibular system may contribute to bone homeostasis in older adults, notably of the weight-bearing hip bones at greatest risk of osteoporotic fracture. Further longitudinal analysis of vestibular function and bone mineral density in humans is needed to characterize this relationship and investigate the potential confounding effect of physical activity.

  6. An integrated modeling study on the effects of mineral dust and sea salt particles on clouds and precipitation

    NASA Astrophysics Data System (ADS)

    Solomos, S.; Kallos, G.; Kushta, J.; Astitha, M.; Tremback, C.; Nenes, A.; Levin, Z.

    2010-10-01

    The amount of airborne particles that will nucleate and form cloud droplets under specific atmospheric conditions, depends on their number concentration, size distribution and chemical composition. Aerosol is affected by primary particle emissions, gas-phase precursors, their transformation and interaction with atmospheric constituents, clouds and dynamics. A comprehensive assessment of these interactions requires an integrated approach; most studies however decouple aerosol processes from cloud and atmospheric dynamics and cannot account for all the feedbacks involved in aerosol-cloud-climate interactions. This study addresses aerosol-cloud-climate interactions with the Integrated Community Limited Area Modeling System (ICLAMS) that includes online parameterization of the physical and chemical processes between air quality and meteorology. ICLAMS is an extended version of the Regional Atmospheric Modeling System (RAMS) and it has been designed for coupled air quality - meteorology studies. Model sensitivity tests for a single-cloud study as well as for a case study over the Eastern Mediterranean illustrate the importance of aerosol properties in cloud formation and precipitation. Mineral dust particles are often coated with soluble material such as sea-salt, thus exhibiting increased CCN efficiency. Increasing the percentage of salt-coated dust particles by 15% in the model resulted in more vigorous convection and more intense updrafts. The clouds that were formed extended about 3 km higher and the initiation of precipitation was delayed by one hour. Including on-line parameterization of the aerosol effects improved the model bias for the twenty-four hour accumulated precipitation by 7%. However, the spatial distribution and the amounts of precipitation varied greatly between the different aerosol scenarios. These results indicate the large portion of uncertainty that remains unresolved and the need for more accurate description of aerosol feedbacks in atmospheric

  7. Dominance of goethite over hematite in iron oxides of mineral dust from Western Africa: Quantitative partitioning by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Formenti, P.; Caquineau, S.; Chevaillier, S.; Klaver, A.; Desboeufs, K.; Rajot, J. L.; Belin, S.; Briois, V.

    2014-11-01

    This paper reports on the X-ray absorption analysis of samples of mineral dust emitted from or transported to Western Africa. We found that iron oxides account, by mass, for 38% to 72% of the total elemental iron. They are composed of minerals in the Fe(III) oxidation state: goethite (FeO·OH) and hematite (Fe2O3). The apparent fraction of iron oxide attributed to goethite is higher than hematite regardless of the source region from which the dust originated. The goethite percent content of iron oxides is in the range 52-78% (by mass), the highest values being measured for dust originating in the Sahel. The limited number of samples analyzed and the sample-to-sample variability prevent us from concluding firmly on the regional variability of the goethite-to-hematite ratio. Based on the experimental data on mineralogical composition and on concurrent measurements of the number size distribution, the optical properties of mineral dust have been calculated in a Mie approximation for homogeneous spherical particles. At 550 nm, the single-scattering albedo ω0 ranges between 0.89 and 0.93, the asymmetry factor g ranges between 0.76 and 0.8 and the mass extinction efficiency kext varies between 0.5 and 1.1 m2 g-1; these values are all in the range of those from independent direct measurements. Neglecting the partitioning between hematite and goethite and the assimilation of iron oxides by hematite, as it is often done with models, lowers the single-scattering albedo and increases the asymmetry factor in the UV-visible spectral region below 550 nm. The mass extinction efficiency is insensitive to the nature of the iron oxides but rather responds to variations in the number size distribution. The mineralogy of iron oxides should therefore be taken into account when assessing the effect of mineral dust on climate and atmospheric chemistry, in particular via interactions involving photolysis.

  8. Temporal variability of mineral dust in southern Tunisia: analysis of 2 years of PM10 concentration, aerosol optical depth, and meteorology monitoring

    NASA Astrophysics Data System (ADS)

    Bouet, Christel; Taieb Labiadh, Mohamed; Bergametti, Gilles; Rajot, Jean Louis; Marticorena, Béatrice; Sekrafi, Saâd; Ltifi, Mohsen; Féron, Anaïs; des Tureaux, Thierry Henry

    2016-04-01

    The south of Tunisia is a region very prone to wind erosion. During the last decades, changes in soil management have led to an increase in wind erosion. In February 2013, a ground-based station dedicated to the monitoring of mineral dust (that can be seen in this region as a proxy of the erosion of soils by wind) was installed at the Institut des Régions Arides (IRA) of Médenine (Tunisia) to document the temporal variability of mineral dust concentrations. This station allows continuous measurements of surface PM10 concentration (TEOM™), aerosol optical depth (CIMEL sunphotometer), and total atmospheric deposition of insoluble dust (CARAGA automatic sampler). The simultaneous monitoring of meteorological parameters (wind speed and direction, relative humidity, air temperature, atmospheric pressure, and precipitations) allows to analyse the factors controlling the variations of mineral dust concentration from the sub-daily to the annual scale. The results from the two first years of measurements of PM10 concentration are presented and discussed. In average on year 2014, PM10 concentration is 56 μg m-3. However, mineral dust concentration highly varies throughout the year: very high PM10 concentrations (up to 1,000 μg m-3 in daily mean) are frequently observed during wintertime and springtime, hardly ever in summer. These episodes of high PM10 concentration (when daily average PM10 concentration is higher than 240 μg m-3) sometimes last several days. By combining local meteorological data, air-masses trajectories, sunphotometer measurements, and satellite imagery, the part of the high PM10concentration due to local emissions and those linked to an advection of dusty air masses by medium and long range transport from the Sahara desert is quantified.

  9. Sclerostin is expressed in osteoclasts from aged mice and reduces osteoclast-mediated stimulation of mineralization.

    PubMed

    Ota, Kuniaki; Quint, Patrick; Ruan, Ming; Pederson, Larry; Westendorf, Jennifer J; Khosla, Sundeep; Oursler, Merry Jo

    2013-08-01

    Osteoclast-mediated bone resorption precedes osteoblast-mediated bone formation through early adulthood, but formation fails to keep pace with resorption during aging. We previously identified several factors produced by osteoclasts that promote bone formation. In this study, we determined if osteoclast-produced factors contribute to the impaired bone formation with aging. We previously found that mice between the ages of 18 and 22 months develop age-related bone loss. Bone marrow-derived pre-osteoclasts were isolated from 6-week, 12-month, and 18- to 24-month-old mice and differentiated into osteoclasts in vitro. Conditioned media were collected and compared for osteoblast mineralization support. Conditioned medium from osteoclasts from all ages was able to support mineralization of bone marrow stromal cells. Concentrating the conditioned medium from 6-week-old and 12-month-old mouse marrow cells-derived osteoclasts enhanced mineralization support whereas concentrated conditioned medium from 18- to 24-month-old mouse marrow-derived osteoclasts repressed mineralization compared to base medium. This observation suggests that an inhibitor of mineralization was secreted by aged murine osteoclasts. Gene and protein analysis revealed that the Wnt antagonist sclerostin was significantly elevated in the conditioned media from 24-month-old mouse cells compared to 6-week-old mouse cells. Antibodies directed to sclerostin neutralized the influences of the aged mouse cell concentrated conditioned media on mineralization. Sclerostin is primarily produced by osteocytes in young animals. This study demonstrates that osteoclasts from aged mice also produce sclerostin in quantities that may contribute to the age-related impairment in bone formation.

  10. Risk evaluation and exposure control of mineral dust containing free crystalline silica: a study case at a quarry in the Recife Metropolitan Area.

    PubMed

    Lira, Mario; Kohlman Rabbani, E; Barkokébas Junior, Beda; Lago, Eliane

    2012-01-01

    During the production of aggregates at quarry sites, elevated quantities of micro-particulate mineral dust are produced in all stages of the process. This dust contains appreciable amounts of free crystalline silica in a variety of forms which, if maintained suspended in the air in the work environment, expose the workers to the risk of developing occupational silicosis, which causes reduced ability to work and potential shortening of lifespan. This study was conducted to qualitatively and quantitatively evaluate workers' exposure to mineral dust containing free crystalline silica at a midsized quarry in the Recife metropolitan area, in the State of Pernambuco. It involved evaluation of the industrial process, collection and analysis of representative dust samples, and interviews with the management team of the company with the intent to assess the compliance of the company with Regulatory Standard (NR) 22--Occupational safety and health in mining. In order to assist the company in managing risks related to dust exposure, three protocols were developed, implemented and made available, the first based on NR 22, from which the company was also given an economic safety indicator, the second based on the recommendations and requirements of Fundacentro to implement a Respiratory Protection Program and, finally, an assessment protocol with respect to the guidelines of the International Labor Organization to implement a health and safety management system. This study also showed the inadequacy of the formula for calculating tolerance limits in Brazilian legislation when compared with the more strict internationally accepted control parameters. From the laboratory results, unhealthy conditions at the quarry site were confirmed and technical and administrative measures were suggested to reduce and control dust exposure at acceptable levels, such as the implementation of an occupational health and safety management system, integrated with other management systems. From these

  11. Influence of animal age on body concentrations of minerals in Japanese quail (Coturnix japonica).

    PubMed

    Sales, J; Skřivan, M; Englmaierová, M

    2014-12-01

    Mathematical modelling of the relationships between mineral inputs and outputs would enable the prediction of mineral requirements of poultry under a wide range of conditions. To establish the feasibility of possible modelling of mineral requirements, the current study aimed to describe the individual mineral concentrations of whole bodies of quail over the life cycle from hatching to 70 days of age. Quail were reared indoors without any restrictions that could limit growth. Sampling of birds (n = 6-18) was carried out at 0, 3, 7, 14, 21, 35, 49 and 70 days after hatching. Freeze-dried samples of whole bodies (digestive contents removed) were analysed for ash, and macrominerals (calcium, magnesium, phosphorus, potassium, sodium) and microminerals (copper, iron, manganese, nickel, selenium, zinc). Ash concentration followed a curvilinear trend, with a maximum of 101.7 g/kg dry matter at 32.77 days. Individual mineral concentrations, expressed as a proportion of ash, were fluctuating over time, with the most prominent changes at 3 days and again at either 14 or 21 days. Dissimilar patterns in individual mineral concentrations resulted that ratios between minerals followed inconsistent patterns over time. Although mineral contents in absolute quantities can be described through modelling over the entire life cycle of the bird, it can be concluded that variable concentrations of individual minerals could complicate further model development.

  12. Mineralization of mandibular third molars can estimate chronological age--Brazilian indices.

    PubMed

    de Oliveira, Fernando Toledo; Capelozza, Ana Lúcia Álvares; Lauris, José Roberto Pereira; de Bullen, Izabel Regina Fischer Rubira

    2012-06-10

    Forensic age estimation is an important element of anthropological research, as it produces one of the primary sources of data that researchers use to establish the identity of a person living or the identity of unknown bodily remains. The aim of this study was to determine if the chronology of third molar mineralization could be an accurate indicator of estimated age in a sample Brazilian population. If so, mineralization could determine the probability of an individual being 18 years or older. The study evaluated 407 panoramic radiographs of males and females from the past 5 years in order to assess the mineralization status of the mandibular third molars. The evaluation was carried out using an adaptation of Demirjian's system. The results indicated a strong correlation between chronological age and the mineralization of the mandibular third molars. The results indicated that modern Brazilian generation tends to demonstrate an earlier mandibular third molar mineralization than older Brazilian generation and people of other nationalities. Males reached developmental stages slightly earlier than females, but statistically significant differences between the sex were not found. The probability that an individual with third molar mineralization stage H had reached an age of 18 years or older was 96.8-98.6% for males and females, respectively.

  13. Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Boucher, H.; Caquineau, S.; Chevaillier, S.; Cuesta, J.; Formenti, P.

    2014-10-01

    Experimental estimations of the infrared refractive index of African mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5-25 μm. Five dust samples collected at Banizoumbou (Niger) and Tamanrasset (Algeria) during dust events originated from different Western Saharan and Sahelian areas have been investigated. The real (n) and imaginary (k) parts of the refractive index obtained for the different dust samples vary in the range 1.1-2.7 and 0.05-1.0, respectively, and are strongly sensitive to the mineralogical composition of the particles, especially in the 8-12 and 17-25 μm spectral intervals. Dust absorption is controlled mainly by clays (kaolinite, illite, smectite) and, to a lesser extent, by quartz and calcium-rich minerals (e.g. calcite, gypsum). Significant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the OPAC (Optical Properties of Aerosols and Clouds) database. The different data sets appear comparable in magnitude, with our values of n and k falling within the range of variability of past studies. However, literature data fail in accurately reproducing the spectral signatures of the main minerals, in particular clays, and they significantly overestimate the contribution of quartz. Furthermore, the real and the imaginary parts of the refractive index from some literature studies are found not to verify the Kramers-Kronig relations, thus being theoretically incorrect. The comparison between our results, from western Africa, and literature data, from different locations in Europe, Africa, and the Caribbean, nonetheless, confirms the expected large variability of the dust infrared refractive index. This highlights the necessity for an extended systematic investigation of dust properties at infrared wavelengths. For the five analysed dust samples, aerosol intensive optical properties relevant to

  14. Chronological age estimation of third molar mineralization of Han in southern China.

    PubMed

    Zeng, Dong Lin; Wu, Zhi Ling; Cui, Min Yi

    2010-03-01

    In order to study the chronology of age of third molar mineralization of Han in southern China, Demirjian staging method was used to determine the stage of four third molars (18, 28, 38, 48) mineralization in 3,100 Han in southern China aged 4.1-26.9 years based on radiological evidence from digital orthopantomograms. The mean age of the 3,100 patients was 15.96 +/- 4.73 years, including 1,200 male (mean age, 15.32 +/- 4.62) and 1,900 female (mean age, 16.35 +/- 4.76). Results show that there was no significant difference in mineralization between 18 and 28 and 38 and 48 of male or female. However, significant difference was observed between 28 and 38 of female at stage C; 28 was 0.25 years earlier than 38. In male, at stage G, 38 was 0.61 years earlier than 28, and 48 was 0.62 years earlier than 18. At stages D, E, F, G, and H, male 48 was 0.34, 0.66, 0.72, 1.34, and 0.76 years earlier than that of female, respectively. At stages A, D, E, F, G, and H, male 38 was 0.73, 0.26, 0.56, 0.91, 1.29, and 0.70 years earlier than that of female, respectively. At stages B, E, F, G, and H, the mineralization mean age of male 18 was 0.54, 0.50, 0.76, 0.92, and 0.58 years earlier than that of female, respectively. At stages E, F, G, and H, the mineralization mean age of male 28 was 0.51, 0.76, 0.92, and 0.49 years earlier than that of female, respectively. After reviewing the literature, the chronological mineralization age of 48, at stages D to G, of Han in southern China was 1 to 4.6 years earlier than that of Japanese and 1 to 3 years earlier than that of German. The mean age at stage H of 48 of Han in southern China was similar to Turkish, Black African, Japanese, and German, but was later than Spanish. Finally, the conclusions are: (1) in the same gender group of Han in southern China, the mineralization ages between two sides in upper or lower jaw are very similar, and (2) the chronology mean age and complete time of third molar mineralization of male were earlier than

  15. Is there a lower size limit for mineral dust ice nuclei in the immersion mode?

    NASA Astrophysics Data System (ADS)

    Welti, André; Lohmann, Ulrike; Kanji, Zamin A.

    2014-05-01

    There is observational evidence that atmospheric aerosol particles which are able to trigger ice nucleation are larger than approximately 100nm (e.g. Fletcher, 1959). On the other hand observations of IN active macromolecules which have been proposed to be responsible for the enhanced ice formation in the washing water of pollen indicate no such size limit (Augustin et al., 2013). We present measurements on the size dependent ability of feldspars and clay minerals to serve as ice nuclei. The size dependent frozen fraction of droplets containing monodisperse, single immersed particles is investigated with the IMCA/ZINC experimental setup (Lüönd et. al., 2010). To meet the requirement of a narrow particle size distribution, special care is taken to generate monodisperse particles in the lower size range, by using a two stage size selection setup including a differential mobility analyser and a centrifugal particle mass analyser. From the analysis of the temperature at which 50% of the particles initiate ice nucleation, we find a logarithmic dependence of the median ice nucleation temperature on the particle surface area, with no discontinuous decrease in the ice nucleation ability of 100nm particles. The medium ice nucleation temperature of clay minerals however reaches homogeneous nucleation temperatures in this size range. The logarithmic dependence of the median ice nucleation temperature on particle surface area is addressed by comparing the experimental findings to predictions using the classical nucleation theory and the active site approach. Augustin, S., Wex, H., Niedermeier, D., Pummer, B., Grothe, H., Hartmann, S., Tomsche, L., Clauss, T., Voigtländer, J., Ignatius, K., and Stratmann, F.: Immersion freezing of birch pollen washing water, Atmos. Chem. Phys., 13, 10989-11003, 2013. Fletcher, N.H.: On Ice-Crystal Production by Aerosol Particles, J. Meteo., 16, 173-180, 1959. Lüönd, F., Stetzer, O., Welti, A., and Lohmann, U.: Experimental study on the ice

  16. Investigation of mineral filler effects on the aging process of asphalt mastics

    NASA Astrophysics Data System (ADS)

    Moraes, Raquel

    Aging of asphalt binders is induced by chemical and/or physicochemical changes during production of pavement and throughout its service life. Although binder aging in pavement always occurs while binder is in contact with aggregates and mineral filler, in most laboratory aging studies, and in current specifications, asphalt binders are individually aged without accounting for aggregate induced interactions. Past research has had conflicting findings, attributing both mitigating and/or catalytic effects to the presence of mineral filler in asphalt binder with regards to oxidative aging. Thus, in the present study it was hypothesized that evaluation of asphalt oxidative aging without regard to interactive effect of the presence of mineral filler is inadequate as a specification tool. Effects of mineral fillers on oxidative aging of asphalt is investigated by means of accelerated aging of mastics (asphalt and fillers) in Pressure Aging Vessel (PAV). Testing matrix included aging evaluation of mastics containing different fillers content, mineralogy, and surface area. Results showed that low-temperature behavior of aged mastic can be modified by controlling filler concentration and type. Fillers acts as an agent adsorbing heavy fractions of asphalt binder, therefore reducing stiffness and changing glass-transition temperature. Also, during oxidative aging of asphalt binders and mastics, both diffusion and adsorption mechanisms play a role in the rate of aging of asphaltic material. A method to characterize the behavior of mastics with aging was also developed by monitoring the mastics |G*| aging index (ratio of complex modulus before and after aging). Gel Permeation Chromatography (GPC) testing results supported mentioned findings regarding |G*| changes, as the presence of mineral filler appears to decelerate the rate of production of larger molecular size oxidation products in the binder phase of mastics. Implication of the findings is that change in molecular size

  17. Local geological dust in the area of Rome (Italy): linking mineral composition, size distribution and optical properties to radiative transfer modelling

    NASA Astrophysics Data System (ADS)

    Pietrodangelo, Adriana; Salzano, Roberto; Bassani, Cristiana; Pareti, Salvatore; Perrino, Cinzia

    2015-04-01

    Airborne mineral dust plays a key role in the energy balance of the Earth - atmosphere coupled system. The microphysical and optical properties of dust drive the direct radiative effects and are in turn influenced by the dust mineralogical composition. The latter varies largely, depending on the geology of the source region. Knowledge gaps still exist about relationships between the scattering and absorption of solar and terrestrial radiation by mineral dust and its mineralogical, size distribution and particle morphology features; this also affects the reliability of radiative transfer (RT) modelling estimates (Hansell et al., 2011). In this study, these relationships were investigated focusing on the crustal suspended PM10 dust, sourced from outcropping rocks of the local geological domains around Rome (Latium, Italy). The mineral composition variability of the Latium rocks ranges from the silicate-dominated (volcanics domain) to the calcite-dominated (travertine), through lithological materials composed in different proportions by silicates, silica and calcite, mainly (limestone series, siliciclastic series) (Cosentino et al., 2009). This peculiarity of the Latium region was thus exploited to investigate the behavior of the size distribution, optical properties and radiative transfer at BOA (Bottom Of Atmosphere) of the suspended dust PM10 fraction with the variability of mineral composition. Elemental source profiles of the same dust samples were previously determined (Pietrodangelo et al., 2013). A multi-faceted analysis was performed, and outcomes from the following approaches were merged: individual-particle scanning electron microscopy combined with X-ray energy-dispersive microanalysis (SEM XEDS), bulk mineralogical analysis by X-ray diffraction (XRD), size distribution fit of the individual-particle data set and modelling of the dust optical and radiative properties. To this aim, the 6SV atmospheric radiative transfer code (Kotchenova et al., 2008

  18. Particle-area dependence of mineral dust in the immersion mode: investigations with freely suspended drops in an acoustic levitator

    NASA Astrophysics Data System (ADS)

    Diehl, K.; Debertshäuser, M.; Eppers, O.; Schmithüsen, H.; Mitra, S. K.; Borrmann, S.

    2014-05-01

    The heterogeneous freezing temperatures of supercooled drops were measured by using an acoustic levitator. This technique allows to freely suspending single drops in air without electrical charges thereby avoiding any electrical influences which may affect the freezing process. Heterogeneous nucleation caused by several mineral dust particles (montmorillonite, two types of illite) was investigated in the immersion mode. Drops of 1 \\unit{mm} in radius were monitored by a video camera during cooling down to -28 °C to simulate the tropospheric temperature range. The surface temperature of the drops was remotely determined with an infra-red thermometer so that the onset of freezing was indicated. For comparisons, measurements with one particle type were additionally performed in the Mainz vertical wind tunnel with drops of 340 \\unit{{μ}m} radius freely suspended. The data were interpreted regarding the particle surfaces immersed in the drops. Immersion freezing was observed in a temperature range between -13 and -26 °C in dependence of particle type and surface area per drop. The results were evaluated by applying two descriptions of heterogeneous freezing, the stochastic and the singular model.

  19. Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Boucher, H.; Caquineau, S.; Chevaillier, S.; Cuesta, J.; Formenti, P.

    2014-04-01

    Experimental estimations of the infrared refractive index of African mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5-25 μm. Five dust samples collected at Banizoumbou (Niger) and Tamanrasset (Algeria) during dust events originated from different Western Saharan and Sahelian areas have been investigated. The obtained real (n) and imaginary (k) parts of the refractive index for the different dust cases vary in the range 1.1-2.7 and 0.05-1.0, respectively, and appear to be strongly sensitive to the mineralogical composition of the particles, especially in the 8-12 μm and 17-25 μm spectral intervals. Dust absorption is controlled mainly by clays, and, in minor fraction, by quartz and Ca-rich minerals. Size distribution, and the coarse fraction in particular, plays also a role in determining the refractive index. Significant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the OPAC (Optical Properties of Aerosols and Clouds) database. The different datasets appear comparable in magnitude, with our values of n and k falling in the range of variability of past studies. However, literature data fail in accurately reproducing the spectral signatures of main minerals, in particular clays, and they significantly overestimate the contribution of quartz. We also found that the real and the imaginary parts of the refractive index from part of literature studies do not verify Kramers-Kronig relations, thus resulting theoretically incorrect. The comparison between our results, from Western Africa, and literature data, from different locations in Europe, Africa, and the Caribbean, nonetheless, confirms the expected large variability of the infrared refractive index of dust, thus highlighting the necessity for an extended systematic investigation. Aerosol intensive optical properties relevant to radiative transfer

  20. Immersion freezing of supermicron mineral dust particles: freezing results, testing different schemes for describing ice nucleation, and ice nucleation active site densities.

    PubMed

    Wheeler, M J; Mason, R H; Steunenberg, K; Wagstaff, M; Chou, C; Bertram, A K

    2015-05-14

    Ice nucleation on mineral dust particles is known to be an important process in the atmosphere. To accurately implement ice nucleation on mineral dust particles in atmospheric simulations, a suitable theory or scheme is desirable to describe laboratory freezing data in atmospheric models. In the following, we investigated ice nucleation by supermicron mineral dust particles [kaolinite and Arizona Test Dust (ATD)] in the immersion mode. The median freezing temperature for ATD was measured to be approximately -30 °C compared with approximately -36 °C for kaolinite. The freezing results were then used to test four different schemes previously used to describe ice nucleation in atmospheric models. In terms of ability to fit the data (quantified by calculating the reduced chi-squared values), the following order was found for ATD (from best to worst): active site, pdf-α, deterministic, single-α. For kaolinite, the following order was found (from best to worst): active site, deterministic, pdf-α, single-α. The variation in the predicted median freezing temperature per decade change in the cooling rate for each of the schemes was also compared with experimental results from other studies. The deterministic model predicts the median freezing temperature to be independent of cooling rate, while experimental results show a weak dependence on cooling rate. The single-α, pdf-α, and active site schemes all agree with the experimental results within roughly a factor of 2. On the basis of our results and previous results where different schemes were tested, the active site scheme is recommended for describing the freezing of ATD and kaolinite particles. We also used our ice nucleation results to determine the ice nucleation active site (INAS) density for the supermicron dust particles tested. Using the data, we show that the INAS densities of supermicron kaolinite and ATD particles studied here are smaller than the INAS densities of submicron kaolinite and ATD particles

  1. Immersion freezing of supermicron mineral dust particles: freezing results, testing different schemes for describing ice nucleation, and ice nucleation active site densities.

    PubMed

    Wheeler, M J; Mason, R H; Steunenberg, K; Wagstaff, M; Chou, C; Bertram, A K

    2015-05-14

    Ice nucleation on mineral dust particles is known to be an important process in the atmosphere. To accurately implement ice nucleation on mineral dust particles in atmospheric simulations, a suitable theory or scheme is desirable to describe laboratory freezing data in atmospheric models. In the following, we investigated ice nucleation by supermicron mineral dust particles [kaolinite and Arizona Test Dust (ATD)] in the immersion mode. The median freezing temperature for ATD was measured to be approximately -30 °C compared with approximately -36 °C for kaolinite. The freezing results were then used to test four different schemes previously used to describe ice nucleation in atmospheric models. In terms of ability to fit the data (quantified by calculating the reduced chi-squared values), the following order was found for ATD (from best to worst): active site, pdf-α, deterministic, single-α. For kaolinite, the following order was found (from best to worst): active site, deterministic, pdf-α, single-α. The variation in the predicted median freezing temperature per decade change in the cooling rate for each of the schemes was also compared with experimental results from other studies. The deterministic model predicts the median freezing temperature to be independent of cooling rate, while experimental results show a weak dependence on cooling rate. The single-α, pdf-α, and active site schemes all agree with the experimental results within roughly a factor of 2. On the basis of our results and previous results where different schemes were tested, the active site scheme is recommended for describing the freezing of ATD and kaolinite particles. We also used our ice nucleation results to determine the ice nucleation active site (INAS) density for the supermicron dust particles tested. Using the data, we show that the INAS densities of supermicron kaolinite and ATD particles studied here are smaller than the INAS densities of submicron kaolinite and ATD particles

  2. Vitamin D status is associated with bone mineral density and bone mineral content in preschool-aged children.

    PubMed

    Hazell, Tom J; Pham, Thu Trang; Jean-Philippe, Sonia; Finch, Sarah L; El Hayek, Jessy; Vanstone, Catherine A; Agellon, Sherry; Rodd, Celia J; Weiler, Hope A

    2015-01-01

    This study examined the associations between vitamin D status, bone mineral content (BMC), areal bone mineral density (aBMD), and markers of calcium homeostasis in preschool-aged children. Children (n=488; age range: 1.8-6.0 y) were randomly recruited from Montreal. The distal forearm was scanned using a peripheral dual-energy X-ray absorptiometry scanner (Lunar PIXI; GE Healthcare, Fairfield, CT). A subset (n=81) had clinical dual-energy X-ray absorptiometry (cDXA) scans (Hologic 4500A Discovery Series) of lumbar spine (LS) 1-4, whole body, and ultradistal forearm. All were assessed for plasma 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone concentrations (Liaison; Diasorin), ionized calcium (ABL80 FLEX; Radiometer Medical A/S), and dietary vitamin D and calcium intakes by survey. Age (p<0.001) and weight-for-age Z-score (p<0.001) were positively associated with BMC and aBMD in all regression models, whereas male sex contributed positively to forearm BMC and aBMD. Having a 25(OH)D concentration of >75 nmol/L positively associated with forearm and whole body BMC and aBMD (p<0.036). Sun index related to (p<0.029) cDXA forearm and LS 1-4 BMC and whole-body aBMD. Nutrient intakes did not relate to BMC or aBMD. In conclusion, higher vitamin D status is linked to higher BMC and aBMD of forearm and whole body in preschool-aged children.

  3. Exogenous dust delivery into the Saturnian system and the age of Saturn's rings

    NASA Astrophysics Data System (ADS)

    Kempf, S.; Horanyi, M.; Srama, R.; Altobelli, N.

    2015-10-01

    Even 450 years after Galileo Galilei's discovery of Saturn's rings, their origin and evolution is still not known. The rings are the brightest of the four ring systems of the solar system and have at least the mass of the moon Mimas[?]. Interactions with Saturn's moons and viscous spreading of the ring material seem to imply a ring age of about a tenth of the age of the Saturnian system of about 4.5 billion years[?, ?]. A young ring age is problematic because the disruption of a Mimas-sized body or a comet in the Roche zone of Saturn would result in a ring with a much larger rock content than observed today[?, ?, ?]. The unique ring color resulting mainly from the pollution of the ring material with interplanetary meteoroids provides a key for constraining the ring age[?, ?, ?]. Here we report on the first direct measurements of the meteoroid flux into the Saturnian system byCassini's Cosmic Dust Analyzer (CDA).We measured the impact speed vectors of 133 extrinsic micrometeoroids # 2μm and determined their orbital elements. We determined the mass flux into the Saturnian system to be 10-18kg/m2s. This finding suggest a ring exposure time of 4.5 billion years and is in support of an early ring generation from a proto-Titan during the formation of the Saturnian system[?].

  4. Investigation of aged aerosols in size-resolved Asian dust storm particles transported from Beijing, China, to Incheon, Korea, using low-Z particle EPMA

    NASA Astrophysics Data System (ADS)

    Geng, H.; Hwang, H.; Liu, X.; Dong, S.; Ro, C.-U.

    2014-04-01

    This is the first study of Asian dust storm (ADS) particles collected in Beijing, China, and Incheon, Korea, during a spring ADS event. Using a seven-stage May impactor and a quantitative electron probe X-ray microanalysis (ED-EPMA, also known as low-Z particle EPMA), we examined the composition and morphology of 4200 aerosol particles at stages 1-6 (with a size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent aerodynamic diameter, respectively) collected during an ADS event on 28-29 April 2005. The results showed that there were large differences in the chemical compositions between particles in sample S1 collected in Beijing immediately after the peak time of the ADS and in samples S2 and S3, which were collected in Incheon approximately 5 h and 24 h later, respectively. In sample S1, mineral dust particles accounted for more than 88% in relative number abundance at stages 1-5; and organic carbon (OC) and reacted NaCl-containing particles accounted for 24% and 32%, respectively, at stage 6. On the other hand, in samples S2 and S3, in addition to approximately 60% mineral dust, many sea spray aerosol (SSA) particles reacted with airborne SO2 and NOx (accounting for 24% and 14% on average in samples S2 and S3, respectively), often mixed with mineral dust, were encountered at stages 1-5, and (C, N, O, S)-rich particles (likely a mixture of water-soluble organic carbon with (NH4)2SO4 and NH4NO3) were abundantly observed at stage 6 (accounting for 68% and 51% in samples S2 and S3, respectively). This suggests that an accumulation of sea-salt components on individual ADS particles larger than 1 μm in diameter occurred and many secondary aerosols smaller than 1 μm in diameter were formed when the ADS particles passed over the Yellow Sea. In the reacted or aged mineral dust and SSA particles, nitrate-containing and both nitrate- and sulfate-containing species vastly outnumbered the sulfate-containing species, implying that ambient NOx had a greater influence on the

  5. Dose of house dust mite antigen (P1) inhaled by infants aged one month

    SciTech Connect

    Carswell, F.; Clark, J.; Robinson, P.; Platts-Mills, T.A.

    1983-11-01

    A survey of the habitats occupied by 12 infants of one month of age revealed that approximately 10% of their day was spent in conditions of potential exposure to the major (P1) allergen of the house dust mite, Dermatophagoides pteronyssinus. A respiratory pump which reproduced the minute ventilation of an infant was placed in representative infant habitats. The P1 allergen trapped by the filter in this pump was measured as an estimate of infants' allergen intake. Detectable P1 intake was only present when there was active air disturbance (bed making and vacuuming). The average P1 intake was approximately 3 ng P1/24 hours. Comparison of this P1 intake with that which sensitizes in other situations suggests that it is usually inadequate to sensitize infants.

  6. Quantifying the climatological cloud-free shortwave direct radiative forcing of mineral dust aerosol over the Red Sea

    NASA Astrophysics Data System (ADS)

    Stenchikov, G. L.; Brindley, H. E.; Osipov, S.; Bantges, R. J.; Smirnov, A.; Prakash, P. J.

    2014-12-01

    While there have been a number of campaigns designed to probe dust-climate interactions over much of the world, relatively little attention has been paid to the Red Sea. Because of the remoteness of the area, satellite retrievals provide a crucial tool for assessing aerosol loading over the Sea. However, agreement between aerosol properties inferred from measurements from different instruments, and even in some cases from the same measurements using different retrieval algorithms can be poor, particularly in the case of mineral dust. Ground based measurements, which can be used to evaluate retrievals, are thus highly desirable. Here we take advantage of ship-based hand-held sun-photometer (microtops) observations gathered within the framework of NASA Aerosol Maritime Network from a series of cruises, which took place across the Red Sea during 2011 and 2013. To our knowledge these data represent the first set of detailed aerosol measurements from the Sea. They thus provide a unique opportunity to assess the performance of satellite retrieval algorithms in this region. Here we used the microtops measurements to evaluate the performance of co-located satellite retrievals from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the MODerate Imaging Spectrometer (MODIS). Both algorithms show good agreement with the ship-based measurements and with each other, although it appears that the MODIS cloud detection scheme in particular is rather conservative. The stand alone Rapid Radiative Transfer Model (RRTM) driven by reanalysis meteorological fields is used to estimate the cloud-free aerosol direct radiative effect at the surface and TOA along the ship tracks. The TOA effects are compared to co-located measurements from the Geostationary Earth Radiation Budget (GERB) instrument. Having evaluated both the quality of the retrievals and the ability of the model to capture the associated radiative effect, we will present a climatology of aerosol loading over the

  7. Role of mineral dust, soot, and bacteria in cloud and precipitation formation processes over Indian subcontinent using an atmospheric general circulation model

    NASA Astrophysics Data System (ADS)

    Hazra, Anupam

    2013-06-01

    An aerosol-type specific heterogeneous nucleation parameterization that based on the classical nucleation theory has been implemented into the atmospheric general circulation model (AGCM), ECHAM5. The microphysical responses in precipitation formation to the variation of ice nuclei (IN) species over Indian subcontinent were analyzed using AGCM, considering the immersion freezing nucleation from mineral dust, dust with ammonium sulfate coating, soot and bacteria species. Immersion freezing by bacteria species is found to be dominating in October-December, whereas dust with ammonium sulfate produces more cloud ice in January-March. There are very little differences in cloud ice formation during April-May and June-September among various IN species. There is also a geographic dependence in the role of different IN species in precipitation formation, like bacteria is important in Southern Peninsula and dust particles play a significant role in central India. In nature the emission of ice nucleating active bacteria and non-biological dust, soot into the atmosphere is important and highly dependent on temperature, and precipitation. So it is the worthy of investigation on the role of different kind of aerosols on the microphysics and precipitation processes, the biosphere-atmosphere interaction and climatic research.

  8. The chronological age estimation of third molar mineralization of Han population in southwestern China.

    PubMed

    Qing, Maofeng; Qiu, Lihua; Gao, Zhi; Bhandari, Kishor

    2014-05-01

    The purpose of the study was to estimate the chronology of third molar mineralization in Han population of southwestern China and find its unique characteristics so that it would provide a reference in several legal cases like forensic age estimation. The study used Demirjian's staging method to study 2192 orthopantomograms of 984 male and 1208 female subjects aged between 8 and 25 years. The statistical data was analyzed by Student's t test and ANOVA. The conclusions of the study are: (1) The chronological mineralization age of third molars of Han population in Southwestern China is similar to the Turkish and the Japanese, was earlier than the Austrian and Han of South China, but later than the Spanish. (2) The mineralization timing of the third molars between two sides in maxilla or mandible has no significant differences in the same gender group. (3) There is no significant difference in mineralization of third molars between male and female, except for tooth 48 in Demirjian's stage E. (4) The mineralization of third molar in maxilla is earlier than mandible.

  9. Donor's age and replicative senescence favour the in-vitro mineralization potential of human fibroblasts.

    PubMed

    Boraldi, Federica; Bartolomeo, Angelica; Di Bari, Caterina; Cocconi, Andrea; Quaglino, Daniela

    2015-12-01

    Aberrant mineralization of soft connective tissues (ectopic calcification) may occur as a frequent age-related complication. Still, it remains unclear the role of mesenchymal cell donor's age and of replicative senescence on ectopic calcification. Therefore, the ability of cells to deposit in-vitro hydroxyapatite crystals and the expression of progressive ankylosis protein homolog (ANKH), ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), tissue non specific alkaline phosphatase (TNAP) and osteopontin (OPN) have been evaluated in human dermal fibroblasts derived from neonatal (nHDF) and adult (aHDF) donors (ex-vivo ageing model) or at low and high cumulative population doublings (CPD) up to replicative senescence (in-vitro ageing model). This study demonstrates that: 1) replicative senescence favours hydroxyapatite formation in cultured fibroblasts; 2) donor's age acts as a major modulator of the mineralizing potential of HDF, since nHDF are less prone than aHDF to induce calcification; 3) donor's age and replicative senescence play in concert synergistically increasing the calcification process; 4) the ANKH+ENPP1/TNAP ratio, being crucial for pyrophosphate/inorganic phosphate balance, is greatly influenced by donor's age, as well as by replicative senescence, and regulates mineral deposition; 5) OPN is only modulated by replicative senescence.

  10. Factors that influence the formation and stability of hydrated ferrous sulfate in coal dusts. Possible relation to the emphysema of coal miners

    SciTech Connect

    Huang, Xi; Zalma, R.; Pezerat, H.

    1994-05-01

    Epidemiological studies have shown that a causal relationship may exist between coal dust exposure and emphysema in coal miners. Emphysema can be considered as one of the human pathologies associated with oxidative stress, resulting from oxidant-induced {alpha}{sub 1}-antitrypsin ({alpha}{sub 1}-AT) inactivation and uncontrolled proteolysis of lung tissue. We have previously reported that certain coal dusts contained hydrated ferrous sulfate (FeSO{sub 4}) that inactivated {alpha}{sub 1}-AT. In the present study, we have shown that the FeSO{sub 4} originated from oxidation of pyrite (FeS{sub 2}), which is a typical contaminant of coal dusts. The relative humidity and microenvironmental around individual pyrite particles influence the formation of FeSO{sub 4} in the coal. However, the subsequent human exposure to coal dust containing FeSO{sub 4} depends on the stability of the formed FeSO{sub 4}. We found that pH played the most important role in stabilizing the FeSO{sub 4}, such that a final pH < 4.5 after oxidation of pyrite stabilized FeSO{sub 4}, whereas at high pH the conversion of reactive Fe{sup 2+} to Fe{sup 3+} was immediate. Sulfuric acid (H{sub 2}SO{sub 4}), which is also produced by the oxidation of pyrite, can lower the pH, but it can also be neutralized by other minerals in coal dusts, such as calcite (CaCO{sub 3}). The stability of FeSO{sub 4} in coal dust can also be influenced by the length of exposure to air. Our studies demonstrated that coal samples differed in their capacity to stabilize FeSO{sub 4}. This current study strengthens our previous reported hypothesis that emphysema, which occurs irregularly in coal miners, could be directly related to exposure to coal dust containing FeSO{sub 4}. 35 refs., 3 figs., 4 tabs.

  11. Cellulosic building insulation versus mineral wool, fiberglass or perlite: installer's exposure by inhalation of fibers, dust, endotoxin and fire-retardant additives.

    PubMed

    Breum, N O; Schneider, T; Jørgensen, O; Valdbjørn Rasmussen, T; Skibstrup Eriksen, S

    2003-11-01

    A task-specific exposure matrix was designed for workers installing building insulation materials. A priori, a matrix element was defined by type of task (installer or helper), type of work area (attic spaces or wall cavities) and type of insulation material (slabs from mineral wool, fiberglass or flax; loose-fill cellulosic material or perlite). In the laboratory a mock-up (full scale) of a one-family house was used for simulated installation of insulation materials (four replicates per matrix element). Personal exposure to dust and fibers was measured. The dust was analyzed for content of endotoxin and some trace elements (boron and aluminum) from fire-retardant or mold-resistant additives. Fibers were characterized as WHO fibers or non-WHO fibers. In support of the exposure matrix, the dustiness of all the materials was measured in a rotating drum tester. For installers in attic spaces, risk of exposure was low for inhalation of dust and WHO fibers from slab materials of mineral wool or fiberglass. Slab materials from flax may cause high risk of exposure to endotoxin. The risk of exposure by inhalation of dust from loose-fill materials was high for installers in attic spaces and for some of the materials risk of exposure was high for boron and aluminum. Exposure by inhalation of cellulosic WHO fibers was high but little is known about the health effects and a risk assessment is not possible. For the insulation of walls, the risk of installers' exposure by inhalation of dust and fibers was low for the slab materials, while a high risk was observed for loose-fill materials. The exposure to WHO fibers was positively correlated to the dust exposure. A dust level of 6.1 mg/m3 was shown to be useful as a proxy for screening exposure to WHO fibers in excess of 10(6) fibers/m3. In the rotating drum, slabs of insulation material from mineral wool or fiberglass were tested as not dusty. Cellulosic loose-fill materials were tested as very dusty, and perlite proved to be

  12. Modeling the impact of tropical mesoscale convective systems on Sahelian mineral dust budget: a case study during AMMA SOPs 1-2

    NASA Astrophysics Data System (ADS)

    Bouet, C.; Cautenet, G.; Marticorena, B.; Bergametti, G.; Chatenet, B.; Rajot, J.-L.; Descroix, L.

    2009-04-01

    Tropical mesoscale convective systems (MCSs) are a prominent feature of the African meteorology. A continuous monitoring of the aeolian activity in an experimental site located in Niger showed that such events are responsible for the major part of the annual local wind erosion, i.e. for most of the Sahelian dust emission [Rajot, 2001]. However, the net effect of these MCSs on mineral dust budget has to be estimated: on the one hand, these systems produce extremely high surface wind velocities leading to intense dust uptake, but on the other hand, rainfalls associated with these systems can efficiently remove the emitted dust from the atmosphere. High resolution modeling of MCSs appears as the most relevant approach to assess the budget between dust emission and deposition in such local meteorological systems. As a first step, in order to properly estimate dust emissions, it is necessary to accurately describe the surface wind fields at the local scale. Indeed, dust emission is a threshold phenomenon that depends on the third power of surface wind velocity. This study focuses on a case study of dust emission associated with the passage of a MCS observed during one of the intensive observation period of the international African Monsoon Multidisciplinary Analysis (AMMA - SOPs 1-2) program. The simulations were made using the Regional Atmospheric Modeling System (RAMS) coupled online with the dust production model (DPM) developed by Marticorena and Bergametti [1995] and recently improved by Laurent et al. [2008] for Africa. Two horizontal resolutions were tested (5 km and 2.5 km) as well as two microphysical schemes (a 1-moment scheme [Walko et al., 1995] and a 2-moment scheme [Meyers et al., 1997]). The use of the two convective parameterizations now available in the version 6 of RAMS (Kuo [1995] modified by Molinari [1985] and Molinari and Corsetti [1985], and Kain and Fritsch [1992; 1993]) to simulate cloud convection was also tested. Sensitivity tests have been

  13. Age measurements of potassium-bearing sulfide minerals by the 40Ar/39Ar technique

    USGS Publications Warehouse

    Czamanske, G.K.; Lanphere, M.A.; Erd, Richard C.; Blake, M.C., Jr.

    1978-01-01

    K-Ar ages have been determined for sulfide minerals for the first time. The occurrence of adequate amounts of potassium-bearing sulfides with ideal compositions K3Fe10S14 (???10 wt.% K) and KFe2S3 (???16 wt.% K) in samples from a mafic alkalic diatreme at Coyote Peak, California, prompted an attempt to date these materials. K3Fe10S14, a massive mineral with conchoidal fracture, gives an age of 29.4 ?? 0.5 m.y. (40Ar/39Ar), indistinguishable from the 28.3 ?? 0.4 m.y. (40Ar/39Ar) and 30.2 ?? 1.0 m.y.8 (conventional K-Ar) ages obtained for associated phlogopite (8.7 wt.% K). KFe2S3, a bladed, fibrous sulfide, gives a younger age, 26.5 ?? 0.5 m.y. (40Ar/39Ar), presumably owing to Ar loss. ?? 1978.

  14. High velocity Van de Graaff shots of mineral dust: application to STARDUST and other in situ space missions

    NASA Astrophysics Data System (ADS)

    Postberg, Frank; Srama, Ralf; Trieloff, Mario; Hillier, Jon; Gainsforth, Zack; Westphal, Andrew; Grün, Eberhard; Armes, Steve; Kearsley, Anton

    2010-05-01

    The detection and collection of high velocity interplanetary or interstellar dust grains by space missions is a nontrivial task, as high speed impacts on collectors or detectors may cause significant structural and chemical modification. Hence, simulation of high speed dust impacts is required, e.g. into STARDUST aerogel or foils [1], or impact ionisation time-of-flight mass spectrometers as onboard CASSINI [2,3]. Particle speeds up to 50 km/sec can only be achieved by a Van de Graaff accelerator as operated at the Max-Planck-Institut für Kernphysik (Heidelberg). Here, only charged particles can be ac-celerated: While metals (e.g., Fe, Al) or magnetite work well, ac-celeration of silicates or organics requires a complex chemical coating procedure, to achieve acceptable levels of conductivity. A thin platinum coating [4] was successfully applied to analogue ma-terial like silicates (quartz, orthopyroxene, anorthite, olivine), and carbon rich particles (silicon carbide). Organic and sulfide (e.g. pyrrhotite) grains have been coated with a thin conductive layer of Polypyrrole [5], which allows acceleration in the Van de Graaff. All coated grains were successfully accelerated and provided im-pacts with speeds between 1 - 40 km/s. Impact signals as well as high resolution impact ionisation mass spectra were evaluated using the large area mass analyzer [6] (LAMA). These TOF spectra provide a mass resolution of about 200 and allow for qualitative determination of mineral compounds and isotopes in individual grains. However, while for these kinds of experiments active selection of suitable particle impacts is possible, the preparation for shots into STARDUST collectors requires com-plete control of particle size and speed by an improved new version of specific Particle Selection Unit, which is currently implemented. This provides a clear advantage over shots with a light gas gun where single shots of selected grain within a narrow mass and speed range are not achievable

  15. Mineral dust impact on snow radiative properties in the European Alps combining ground, UAV, and satellite observations

    NASA Astrophysics Data System (ADS)

    Di Mauro, B.; Fava, F.; Ferrero, L.; Garzonio, R.; Baccolo, G.; Delmonte, B.; Colombo, R.

    2015-06-01

    In this paper, we evaluate the impact of mineral dust (MD) on snow radiative properties in the European Alps at ground, aerial, and satellite scale. A field survey was conducted to acquire snow spectral reflectance measurements with an Analytical Spectral Device (ASD) Field Spec Pro spectroradiometer. Surface snow samples were analyzed to determine the concentration and size distribution of MD in each sample. An overflight of a four-rotor Unmanned Aerial Vehicle (UAV) equipped with an RGB digital camera sensor was carried out during the field operations. Finally, Landsat 8 Operational Land Imager (OLI) data covering the central European Alps were analyzed. Observed reflectance evidenced that MD strongly reduced the spectral reflectance of snow, in particular, from 350 to 600 nm. Reflectance was compared with that simulated by parameterizing the Snow, Ice, and Aerosol Radiation radiative transfer model. We defined a novel spectral index, the Snow Darkening Index (SDI), that combines different wavelengths showing nonlinear correlation with measured MD concentrations (R2 = 0.87, root-mean-square error = 0.037). We also estimated a positive instantaneous radiative forcing that reaches values up to 153 W/m2 for the most concentrated sampling area. SDI maps at local scale were produced using the UAV data, while regional SDI maps were generated with OLI data. These maps show the spatial distribution of MD in snow after a natural deposition from the Saharan desert. Such postdepositional experimental data are fundamental for validating radiative transfer models and global climate models that simulate the impact of MD on snow radiative properties.

  16. Direct observation of nitrate and sulfate formations from mineral dust and sea-salts using low- Z particle electron probe X-ray microanalysis

    NASA Astrophysics Data System (ADS)

    Hwang, HeeJin; Ro, Chul-Un

    In the present work, it is demonstrated that a single particle analytical technique, named low- Z particle electron probe X-ray microanalysis, is a practically useful tool for the study of heterogeneous reactions of mineral dust and sea-salts when this analytical technique was applied to a sample collected during an Asian Dust storm event. The technique does not require a special treatment of sample to identify particles reacted in the air. Also, quantitative chemical speciation of reacted particles can provide concrete information on what chemical reaction, if any, occurred for individual particles. Among overall 178 analyzed particles, the number of reacted particles is 81 and heterogeneous chemical reactions mostly occurred on CaCO 3 mineral dust (54 particles) and sea-salts (26 particles). Several observations made for the Asian Dust sample in the present work are: (1) CaCO 3 species almost completely reacted to produce mostly Ca(NO 3) 2 species, and CaSO 4 to a much lesser extent. (2) When reacted particles contain CaSO 4, almost all of them are internally mixed with nitrate. (3) Reacted CaCO 3 particles seem to contain moisture when they were collected. (4) Some reacted CaCO 3 particles have unreacted mineral species, such as aluminosilicates, iron oxide, SiO 2, etc., in the core region. (5) All sea-salt particles are observed to have reacted in the air. Some of them were recrystallized in the air before being collected and they are observed as crystalline NaNO 3 particles. (6) Many sea-salts were collected as water drops, and some of them were fractionally recrystallized on Ag collecting substrate. When sea-salts were not recrystallized on the substrate, they are found as particles internally mixed with NaNO 3 and Mg(NO 3) 2, and in some cases SO 4 and Cl species as additional anions.

  17. Bone mineral density and lifestyle among female students aged 16-24 years.

    PubMed

    Elgán, C; Dykes, A K; Samsioe, G

    2002-04-01

    The objective of the study was to investigate bone mineral density and bone turnover among female students aged 16-24 years in relation to lifestyle factors, such as dietary habits and physical activity, as well as physiological factors, such as age, body weight, and menstrual pattern. Female college and university students (n = 218) were given a validated questionnaire with 34 questions concerning diet, recreational physical activity, alcohol, smoking, menstrual pattern, weight gain and loss. Bone mineral density (BMD) measurements were performed using a heel bone scanner (DEXA). Deoxypyridinoline (DPD) levels were measured in urine samples. The data were analyzed by linear regression and multiple regression analysis. The mean BMD was 0.568 g/cm2. Multiple regression showed that hormonal age was a better predictor of high BMD and low bone mineral turnover than chronological age. The best model predicting high BMD was composed of physical activity, regular menstruation, hormonal age and body weight. Smoking, alcohol consumption and current calcium intake did not contribute to the model. A negative association between BMD and DPD was found, indicating an enhanced bone remodeling. A correlation was found between DPD and hormonal age, chronological age, sugar intake and time with irregular menses. In multiple regression analysis, hormonal age, high sugar intake and weight loss were the factors best predicting DPD. BMD was positively influenced by a healthy lifestyle, including a physically active life and healthy dietary habits without dieting. Our study shows that hormonal age is a stronger BMD predictor than chronological age. Menstrual disturbances might be an indication of a risk for low BMD and might therefore be a reason for measuring BMD among young females.

  18. Seasonal Contribution of Mineral Dust and Otlher Major Components to Particulate Matter at Two Remote Sites in Central Asia

    EPA Science Inventory

    Dust storms are significant contributors to ambient levels of particulate matter (PM) in many areas of the world. Central Asia, an area that is relatively understudied in this regard, is anticipated to be affected by dust storms due to its proximity to several major deserts that ...

  19. Do Forest Age and Soil Depth Affect Carbon and Nitrogen Adsorption in Mineral Horizons?

    NASA Astrophysics Data System (ADS)

    Spina, P. G.; Lovett, G. M.; Fuss, C. B.; Goodale, C. L.; Lang, A.; Fahey, T.

    2015-12-01

    Mineral soils retain large amounts of organic matter through sorption on the surfaces of mineral soils, the largest pools of carbon (C) and nitrogen (N) in the forests of the northeastern U.S. In addition to determining organic matter storage, adsorption and desorption processes are important controllers of runoff chemistry. We are studying adsorption dynamics of mineral soils collected from a chronosequence of hardwood forest sites in the White Mountains, NH to determine how soils vary in their DOM adsorption capacities as a function of effective C and N saturation. We hypothesize that forest age determines proximity to saturation because young forests may need to mine soil organic matter (SOM) in mineral soils to obtain nitrogen to meet growth demands, while the soils of older forests have had time to reaccumulate SOM, eventually reaching C and N saturation. Consequently, we expect adsorption capacities to first increase with forest age in young forests, as the trees mine C and N from mineral surfaces. They will then decrease with forest age in older forests as mining slows and C and N begin to re-accumulate. Batch experiments were conducted with mineral soil samples and dilutions of forest floor leachate. However, preliminary results from a mature forest site (about 100 years old), which we predicted to be a low point of C and N saturation from decades of mining, contradict expectations. Dissolved organic carbon (DOC) adsorption in its shallow mineral soil layers (0-3 cm below E or A horizons) are lower than younger sites ranging from 20 to about 40 years old. In addition to forest age, soil depths also affect N retention dynamics in forest soils. We hypothesized that deeper mineral soils might have greater adsorption capacities due to the fact that they are exposed to less DOC and DON leaching from organic layers and therefore less saturated. Results from the same mature forest site confirm this. Soils from 3-10 cm depth have more potential to adsorb DOC and

  20. Does coal mine dust present a risk for lung cancer. A case-control study of U. S. coal miners

    SciTech Connect

    Ames, R.G.; Amandus, H.; Attfield, M.; Green, F.Y.; Vallyathan, V.

    1983-11-01

    The relationship between the risk of lung cancer mortality and coal mine dust exposure under control by cigarette smoking status is evaluated. Two case-control studies based on 317 white male lung cancer mortality cases are presented. A one-to-one matched-case design allows examination of the risk of coal mine dust exposure and cigarette smoking. A two-to-one matched-case design was employed to examine the lung cancer risk of coal mine dust exposure independent of cigarette smoking. Based upon these data, no evidence of a coal mine dust exposure-lung cancer risk was found, although the expected increased risk for lung cancer in cigarette smokers was observed. There was no evidence of an interactive effect between cigarette smoking and coal mine dust exposure. (13 refs.)

  1. Combined aerosol in-situ measurements during the SALTRACE field experiment for the investigation of Saharan mineral dust microphysical and CCN properties and their spatial-temporal evolution during trans-Atlantic long-range transport

    NASA Astrophysics Data System (ADS)

    Walser, Adrian; Dollner, Maximilian; Sauer, Daniel; Weinzierl, Bernadett

    2015-04-01

    The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE) was a field experiment conducted in June/July 2013, which aimed to investigate the transport and modification of Saharan mineral dust from the Sahara across the Atlantic Ocean to the Caribbean. In addition to ground-based measurements and satellite remote sensing, the DLR Falcon research aircraft was equipped with a number of aerosol in-situ instruments to gain direct information on the properties of airborne aerosol such as size distributions, microphysical, optical and cloud-condensation nuclei (CCN) properties. For the first time, several outbreaks of Saharan dust were probed with the same airborne instrumentation on both sides of the Atlantic. During transport, various processes may take place that modify the aerosol composition. Dry and wet deposition lead to a size-dependent aerosol removal. In case of wet deposition, the removal additionally depends on the particle's ability to act as CCN. Processes in the aqueous phase in subsequently re-evaporating cloud droplets can further alter microphysical and CCN properties of re-released particles. All resulting changes in the size distribution and particle properties impact the radiative feedback and CCN activity of the aged aerosol. This study aims to use combined airborne in-situ measurements to retrieve and compare vertically resolved aerosol size distributions, microphysical and CCN properties for both, short-range transported Saharan dust in the Cape Verde region and long-range transported dust in the Caribbean. We use this data to investigate the influence of long-range transport and associated processes on those properties. We will present vertical profiles of size-resolved aerosol concentrations and volatile fractions as well as CCN activated fractions and draw conclusions for aerosol mixing state, CCN activation diameters and particle hygroscopicities. We will discuss differences in vertical profiles and

  2. New data on the age of gold mineralization of the Lugokan ore cluster (Eastern Transbaikalia)

    NASA Astrophysics Data System (ADS)

    Redin, Yu. O.; Dultsev, V. F.; Nevolko, P. A.; Ponomarchuk, A. V.

    2016-08-01

    The Lugokan ore cluster is located in the southeastern part of Transbaikalia within the Aga-Borzya structural-formational zone of the Mongol-Okhotsk orogenic belt. The 40Ar/39Ar dating of K-bearing minerals of syngenetic to ore parageneses has been carried out applying stepwise heating technique: it has been demonstrated that the earliest gold-ore mineral associations are Au-pyrite-arsenopyrite (163 ±1.9 Ma) and Au-chalcopyrite (160 ±2 Ma). The later parageneses encompass the Au-polymetallic (156.3 ± 1.8 Ma) and Au-Bi (155.9 ± 4.5 Ma) one. By their ages and position in the general scheme of the Late Jurassic magmatism of Eastern Transbaikalia, the Lugokan's ore cluster gold-bearing mineral associations corresponds to the time of intrusion of the Shakhtama pluton (161 Ma) and the Porphyry Complex (159-155 Ma).

  3. Simulation of the mineral dust emission over Northern Africa and Middle East using an aerodynamic roughness length map derived from the ASCAT/PARASOL

    NASA Astrophysics Data System (ADS)

    Basart, Sara; Jorba, Oriol; Pérez García-Pando, Carlos; Prigent, Catherine; Baldasano, Jose M.

    2014-05-01

    Aeolian aerodynamic roughness length in arid regions is a key parameter to predict the vulnerability of the surface to wind erosion, and, as a consequence, the related production of mineral aerosol (e.g. Laurent et al., 2008). Recently, satellite-derived roughness length at the global scale have emerged and provide the opportunity to use them in advanced emission schemes in global and regional models (i.e. Menut et al., 2013). A global map of the aeolian aerodynamic roughness length at high resolution (6 km) is derived, for arid and semi-arid regions merging PARASOL and ASCAT data to estimate aeolian roughness length. It shows very good consistency with the existing information on the properties of these surfaces. The dataset is available to the community, for use in atmospheric dust transport models. The present contribution analyses the behaviour of the NMMB/BSC-Dust model (Pérez et al., 2011) when the ASCAT/PARASOL satellite-derived global roughness length (Prigent et al, 2012) and the State Soil Geographic database Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) is used. We explore the sensitivity of the drag partition scheme (a critical component of the dust emission scheme) and the dust vertical fluxes (intensity and spatial patterns) to the roughness length. An annual evaluation of NMMB/BSC-Dust (for the year 2011) over Northern Africa and the Middle East using observed aerosol optical depths (AODs) from Aerosol Robotic Network sites and aerosol satellite products (MODIS and MISR) will be discussed. Laurent, B., Marticorena, B., Bergametti, G., Leon, J. F., and Mahowald, N. M.: Modeling mineral dust emissions from the Sahara desert using new surface properties and soil database, J. Geophys. Res., 113, D14218, doi:10.1029/2007JD009484, 2008. Menut, L., C. Pérez, K. Haustein, B. Bessagnet, C. Prigent, and S. Alfaro, Impact of surface roughness and soil texture on mineral dust emission

  4. A critical evaluation of the ability of SEVIRI thermal IR RGB rendering to identify mineral dust outbreaks

    NASA Astrophysics Data System (ADS)

    Brindley, H.

    2011-12-01

    Imagery derived from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard the Meteosat Second Generation series of geostationary satellites is routinely exploited for a wide variety of forecasting and hazard monitoring applications. By selectively combining the information from different wavelength channels, red-green-blue (RGB) composites can be produced which offer the potential to identify specific features, while the high temporal resolution of SEVIRI allows these features to be tracked forwards or backwards in time. Amongst the various rendering schemes is one designed to identify and monitor desert dust events using the information content within three thermal IR channels. Imagery produced using this rendering has been widely used by the scientific community as a tool to: identify dust sources and activation; assist with field campaign planning, including aircraft in-flight routing; as a visual tool to probe particular dust generation mechanisms and transport; and to qualitatively assess dust forecast model performance. Since the SEVIRI field of view extends across approximately 70°N to 70°S and 70°E to 70°W the instrument is ideally placed to monitor events originating from both African and Arabian dust sources. Nevertheless, interpretation of the imagery is subjective, and the rendering may fail to produce an unambiguous dust signal under certain conditions. Particular candidates which may confound the identification of a dust signature include high levels of atmospheric water vapour, a strong near-surface temperature inversion, the height of the dust layer, the characteristics of the underlying surface, variability in the dust mineralogical composition and in the size of the dust particles. In this paper a quantitative analysis of the ability of the SEVIRI dust RGB imagery to identify dust presence will be presented. This work is partly motivated by the findings of previous studies, but also by ongoing projects such as the UK-led Fennec

  5. Toxicity of Mineral Dusts and a Proposed Mechanism for the Pathogenesis of Particle-Induced Lung Diseases

    NASA Technical Reports Server (NTRS)

    Lam, C.-W.; Zeidler-Erdely, P.; Scully, R.R.; Meyers, V.; Wallace, W.; Hunter, R.; Renne, R.; McCluskey, R.; Castranova, V.; Barger, M.; Meighan, T.; James, J.T.

    2015-01-01

    Humans will set foot on the moon again. The lunar surface has been bombarded for 4 billion years by micrometeoroids and cosmic radiation, creating a layer of fine dust having a potentially reactive particle surface. To investigate the impact of surface reactivity (SR) on the toxicity of particles, and in particular, lunar dust (LD), we ground 2 Apollo 14 LD samples to increase their SR and compare their toxicity with those of unground LD, TiO2 and quartz. Intratracheally instilled at 0, 1, 2.5, or 7.5 mg/rat, all dusts caused dose-dependent increases in pulmonary lesions, and enhancement of biomarkers of toxicity assessed in bronchoalveolar lavage fluids (BALF). The toxicity of LD was greater than that of TiO2 but less than that of quartz. Three LDs differed 14-fold in SR but were equally toxic; quartz had the lowest SR but was most toxic. These results show no correlation between particle SR and toxicity. Often pulmonary toxicity of a dust can be attributed to oxidative stress (OS). We further observed dose-dependent and dustcytotoxicity- dependent increases in neutrophils. The oxidative content per BALF cell was also directly proportional to both the dose and cytotoxicity of the dusts. Because neutrophils are short-lived and release of oxidative contents after they die could initiate and promote a spectrum of lesions, we postulate a general mechanism for the pathogenesis of particle-induced diseases in the lung that involves chiefly neutrophils, the source of persistent endogenous OS. This mechanism explains why one dust (e.g., quartz or nanoparticles) is more toxic than another (e.g., micrometer-sized TiO2), why dust-induced lesions progress with time, and why lung cancer occurs in rats but not in mice and hamsters exposed to the same duration and concentration of dust.

  6. Injection of mineral dust into the free troposphere during fire events observed with polarization lidar at Limassol, Cyprus

    NASA Astrophysics Data System (ADS)

    Nisantzi, A.; Mamouri, R. E.; Ansmann, A.; Hadjimitsis, D.

    2014-06-01

    Four-year observations (2010-2014) with EARLINET polarization lidar and AERONET sun/sky photometer at Limassol (34.7° N, 33° E), Cyprus, were used to study the soil dust content in lofted fire smoke plumes advected from Turkey. This first systematic attempt to characterize less than 3 days old smoke plumes in terms of particle depolarization contributes to the more general effort to properly describe the life cycle of free-tropospheric smoke-dust mixtures from the emission event to phases of long-range transport (>4 days after emission). We found significant differences in the particle depolarization ratio (PDR) with values from 9-18% in lofted aerosol layers when Turkish fires contributed to the aerosol burden and of 3-13% when Turkish fires were absent. High Ångström exponents of 1.4-2.2 during all these events with lofted smoke layers, occuring between 1 and 3 km height, suggest the absence of a pronounced particle coarse mode. When plotted vs. the travel time (spatial distance between Limassol and last fire area), PDR decreased strongly from initial values around 16-18% (one day travel) to 4-8% after 4 days of travel caused by deposition processes. This behavior was found to be in close agreement with the literature. Computation of particle extinction coefficient and mass concentrations, separately for fine-mode dust, coarse-mode dust, and non-dust aerosol components show extinction-related dust fractions of the order of 10% (for PDR = 4%, travel times >4 days) and 50% (PDR = 15%, one day travel time) and mass-related dust fractions of 25% (PDR = 4%) to 80% (PDR = 15%). Biomass burning should be considered as another source of free tropospheric soil dust.

  7. Injection of mineral dust into the free troposphere during fire events observed with polarization lidar at Limassol, Cyprus

    NASA Astrophysics Data System (ADS)

    Nisantzi, A.; Mamouri, R. E.; Ansmann, A.; Hadjimitsis, D.

    2014-11-01

    Four-year observations (2010-2014) with EARLINET polarization lidar and AERONET sun/sky photometer at Limassol (34.7° N, 33° E), Cyprus, were used to study the soil dust content in lofted fire smoke plumes advected from Turkey. This first systematic attempt to characterize less than 3-day-old smoke plumes in terms of particle linear depolarization ratio (PDR), measured with lidar, contributes to the more general effort to properly describe the life cycle of free-tropospheric smoke-dust mixtures from the emission event to phases of long-range transport (> 4 days after emission). We found significant PDR differences with values from 9 to 18% in lofted aerosol layers when Turkish fires contributed to the aerosol burden and of 3-13 % when Turkish fires were absent. High Ångström exponents of 1.4-2.2 during all these events with lofted smoke layers, occurring between 1 and 3 km height, suggest the absence of a pronounced particle coarse mode. When plotted vs. travel time (spatial distance between Limassol and last fire area), PDR decreased strongly from initial values around 16-18% (1 day travel) to 4-8% after 4 days of travel caused by deposition processes. This behavior was found to be in close agreement with findings described in the literature. Computation of particle extinction coefficient and mass concentrations, derived from the lidar observations, separately for fine-mode dust, coarse-mode dust, and non-dust aerosol components show extinction-related dust fractions on the order of 10% (for PDR =4%, travel times > 4 days) and 50% (PDR =15%, 1 day travel time) and respective mass-related dust fractions of 25% (PDR =4%) to 80% (PDR =15%). Biomass burning should therefore be considered as another source of free tropospheric soil dust.

  8. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Waves in Late Summer, 2003-07

    SciTech Connect

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-12-19

    Episodic events of both Saharan dust outbreaks and African easterly waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan air layer on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximumtropical cyclone activity, in years 2003–07. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, mostAEWsintensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. The authors conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  9. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Wave in Late Summer, 2003-2007

    NASA Technical Reports Server (NTRS)

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-01-01

    Episodic events of both Saharan dust outbreaks and African Easterly Waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan Air Layer (SAL) on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting (WRF) model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximum tropical cyclone activity, in years 2003-2007. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, most AEWs intensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. We conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  10. Radiological age estimation: based on third molar mineralization and eruption in Turkish children and young adults.

    PubMed

    Karadayi, Beytullah; Kaya, Ahsen; Kolusayın, Melek Ozlem; Karadayi, Sükriye; Afsin, Hüseyin; Ozaslan, Abdi

    2012-11-01

    Radiographic evaluation of mineralization and eruption stages of third molars using dental panoramic radiographies can be an efficient tool for chronological age estimation in both forensic sciences and legal medicine. The third molar tooth is utilized for dental age estimation about the age span of 15-23 years because it represents the only tooth still in development. The aim of this study is to obtain and analyze data regarding third molar development and eruption in Turkish population for dental age estimation. A total of 744 dental panoramic radiographies of 394 female and 350 male subjects aged between 8 and 22 years were examined. Third molar development was determined according to the Nolla classification system, and eruption was assessed relative to the alveolar bone level. Mandibular and maxillary third molars were generally found at similar stages of development on both sides. Nolla stage 6 (completed crown calcification) was reached at around the age of 15 in both maxillary and mandibular third molars in both sexes. Alveolar emergence was at around the age of 16 in males and around age of 17 in females. Although third molars' eruption shows greater variability than development of third molars, data which were obtained from this study about eruption of these teeth can be supportive to development data for age estimation.

  11. Cloud ice caused by atmospheric mineral dust - Part 1: Parameterization of ice nuclei concentration in the NMME-DREAM model

    NASA Astrophysics Data System (ADS)

    Nickovic, Slobodan; Cvetkovic, Bojan; Madonna, Fabio; Rosoldi, Marco; Pejanovic, Goran; Petkovic, Slavko; Nikolic, Jugoslav

    2016-09-01

    Dust aerosols are very efficient ice nuclei, important for heterogeneous cloud glaciation even in regions distant from desert sources. A new generation of ice nucleation parameterizations, including dust as an ice nucleation agent, opens the way towards a more accurate treatment of cold cloud formation in atmospheric models. Using such parameterizations, we have developed a regional dust-atmospheric modelling system capable of predicting, in real time, dust-induced ice nucleation. We executed the model with the added ice nucleation component over the Mediterranean region, exposed to moderate Saharan dust transport, over two periods lasting 15 and 9 days, respectively. The model results were compared against satellite and ground-based cloud-ice-related measurements, provided by SEVIRI (Spinning Enhanced Visible and InfraRed Imager) and the CNR-IMAA Atmospheric Observatory (CIAO) in Potenza, southern Italy. The predicted ice nuclei concentration showed a reasonable level of agreement when compared against the observed spatial and temporal patterns of cloud ice water. The developed methodology permits the use of ice nuclei as input into the cloud microphysics schemes of atmospheric models, assuming that this approach could improve the predictions of cloud formation and associated precipitation.

  12. Aged keratinocyte phenotyping: morphology, biochemical markers and effects of Dead Sea minerals.

    PubMed

    Soroka, Yoram; Ma'or, Zeev; Leshem, Yael; Verochovsky, Lilian; Neuman, Rami; Brégégère, François Menahem; Milner, Yoram

    2008-10-01

    The aging process and its characterization in keratinocytes have not been studied in depth until now. We have assessed the cellular and molecular characteristics of aged epidermal keratinocytes in monolayer cultures and in skin by measuring their morphological, fluorometric and biochemical properties. Light and electron microscopy, as well as flow cytometry, revealed increase in cell size, changes in cell shape, alterations in mitochondrial structure and cytoplasmic content with aging. We showed that the expression of 16 biochemical markers was altered in aged cultured cells and in tissues, including caspases 1 and 3 and beta-galactosidase activities, immunoreactivities of p16, Ki67, 20S proteasome and effectors of the Fas-dependent apoptotic pathway. Aged cells diversity, and individual variability of aging markers, call for a multifunctional assessment of the aging phenomenon, and of its modulation by drugs. As a test case, we have measured the effects of Dead Sea minerals on keratinocyte cultures and human skin, and found that they stimulate proliferation and mitochondrial activity, decrease the expression of some aging markers, and limit apoptotic damage after UVB irradiation.

  13. Direct, Longwave Radiative Forcing of Mineral Dust: Improvement of its Estimation by Means of Tools Recently Developed by the EARLINET Community

    NASA Astrophysics Data System (ADS)

    Sicard, Michaël; Muñoz-Porcar, Constantino; Comerón, Adolfo; Rodriguez, Alejandro; Rocadenbosch, Francesc; Barragan, Ruben

    2016-06-01

    The objective of this work is to investigate how the knowledge of the vertically-resolved fine and coarse mode aerosol optical depth modifies the longwave radiative forcing. Since relatively little the EARLINET (European Aerosol Research Lidar Network) community has developed codes that combine sun-photometer and lidar data to retrieve a set of parameters vertically-resolved related to the size distribution (fine and coarse mode extinction coefficients, fine and coarse mode volumetric concentrations, etc.). We concentrate on the case of mineral dust whose size distribution is often dominated by the coarse mode. This work demonstrates that the knowledge of the vertically-resolved fine and coarse mode aerosol optical depth modifies the LW RF as compared to the classical approach with a unique profile of total aerosol optical depth. The results show that when the coarse mode predominates the classical approach underestimates the dust longwave radiative forcing by 10 to 20 % at the surface. The effect at the top of the atmosphere is not systematic because of the predominance of fine particles near the top of the dust layer.

  14. Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006

    NASA Astrophysics Data System (ADS)

    Müller, D.; Lee, K.-H.; Gasteiger, J.; Tesche, M.; Weinzierl, B.; Kandler, K.; Müller, T.; Toledano, C.; Otto, S.; Althausen, D.; Ansmann, A.

    2012-04-01

    The Saharan Mineral Dust Experiment (SAMUM) 2006, Morocco, aimed at the characterization of optical, physical, and radiative properties of Saharan dust. AERONET Sun photometer, several lidars (Raman and high-spectral-resolution instruments), and airborne and ground-based in situ instruments provided us with a comprehensive set of data on particle-shape dependent and particle-shape independent dust properties. We compare 4 measurement days in detail, and we carry out a statistical analysis for some of the inferred data products for the complete measurement period. Particle size distributions and complex refractive indices inferred from the Sun photometer observations and measured in situ aboard a research aircraft show systematic differences. We find differences in the wavelength-dependence of single-scattering albedo, compared to light-scattering computations that use data from SOAP (spectral optical absorption photometer). AERONET data products of particle size distribution, complex refractive index, and axis ratios were used to compute particle extinction-to-backscatter (lidar) ratios and linear particle depolarization ratios. We find differences for these parameters to lidar measurements of lidar ratio and particle depolarization ratio. Differences particularly exist at 355 nm, which may be the result of differences of the wavelength-dependent complex refractive index that is inferred by the methods employed in this field campaign. We discuss various error sources that may lead to the observed differences.

  15. Calcium and vitamin D enriched diets increase and preserve vertebral mineral content in aging laboratory rats.

    PubMed

    Schapira, D; Linn, S; Sarid, M; Mokadi, S; Kabala, A; Silbermann, M

    1995-05-01

    To assess the long-term effect of vitamin D or calcium supplementation on the skeletal metabolism of aging laboratory rodents, 1.5-month-old female Wistar rats were fed with diets containing twice the concentration of vitamin D (group 2) and of calcium (group 3) as in the usual rat chow. Follow-up to 24 months of age did not show significant differences between the enriched-diet groups and the controls (group 1) in terms of the vertebral body weight and protein content. Significantly higher bone mineral contents were found in groups 2 and 3 than were found in controls, as revealed by an increased bone mineral density (BMD: +62%, group 2; +48%, group 3) and vertebral calcium content (+73%, group 2; +84%, group 3). The vertebral alkaline phosphatase enzymatic activity was significantly lower in the enriched diet groups than in controls (-47%, group 2; -45%, group 3). The ratio alkaline phosphatase/acid phosphatase activity was markedly reduced in groups 2 and 3 (-57% and -59%, respectively), which might indicate a diminished rate of bone turnover. The trabecular bone volume (BV/TV) decreased in all groups during senescence, being significantly elevated in group 3 as compared to controls. Vitamin D and calcium dietary supplementations increase the axial mineral bone content in laboratory rats and might reduce the bone turnover. Their influence on the trabecular bone volume has yet to be examined.

  16. Determinants of bone mineral density, bone mineral content, and body composition in a cohort of healthy children: influence of sex, age, puberty, and physical activity.

    PubMed

    Ausili, Emanuele; Rigante, Donato; Salvaggio, Elio; Focarelli, Benedetta; Rendeli, Claudia; Ansuini, Valentina; Paolucci, Valentina; Triarico, Silvia; Martini, Lucilla; Caradonna, Paolo

    2012-09-01

    Interventions directed to the recognition of abnormal bone mineral density, bone mineral content, and body composition in the pediatric age require the definition of factors influencing bone mass acquisition during growth. We have evaluated in a cross-sectional manner by dual-energy X-ray absorptiometry the impact of sex, age, puberty, and physical activity on total body areal bone mineral density, regional (lumbar and femoral) bone mineral densities, bone mineral content, and body composition (fat mass and lean mass) in a cohort of 359 healthy Italian children aged 3-14 years and investigated their specific contribution to bone mass accrual. Statistical multiple regression analysis was performed dividing the population in pre- and post-pubertal groups. Bone mineral density at the lumbar spine has resulted equally distributed in both sexes before puberty while has resulted higher at the femoral necks in males at whatever age. A significant effect on bone mass acquisition was exerted by male sex and lean mass. In the areas where the cortical bone is prevalent, males of the pre-pubertal group have presented the highest values; in the areas where the cancellous bone is prevalent, both sexes were equivalent until the age of 9 years, but after this age, females have presented higher increases, probably related to the inferior dimensional development of lumbar vertebrae. Conclusively, male sex and lean mass seem to represent independent predictors of bone mass accrual in the cortical bone of the examined children, while female sex and pubertal maturation are independent predictors of bone mass accrual in the trabecular bone. PMID:21809005

  17. Cod liver oil consumption at different periods of life and bone mineral density in old age.

    PubMed

    Eysteinsdottir, Tinna; Halldorsson, Thorhallur I; Thorsdottir, Inga; Sigurdsson, Gunnar; Sigurdsson, Sigurdur; Harris, Tamara; Launer, Lenore J; Gudnason, Vilmundur; Gunnarsdottir, Ingibjorg; Steingrimsdottir, Laufey

    2015-07-01

    Cod liver oil is a traditional source of vitamin D in Iceland, and regular intake is recommended partly for the sake of bone health. However, the association between lifelong consumption of cod liver oil and bone mineral density (BMD) in old age is unclear. The present study attempted to assess the associations between intake of cod liver oil in adolescence, midlife, and old age, and hip BMD in old age, as well as associations between cod liver oil intake in old age and serum 25-hydroxyvitamin D (25(OH)D) concentration. Participants of the Age, Gene/Environment Susceptibility-Reykjavik Study (age 66-96 years; n 4798), reported retrospectively cod liver oil intake during adolescence and midlife, as well as the one now in old age, using a validated FFQ. BMD of femoral neck and trochanteric region was measured by volumetric quantitative computed tomography, and serum 25(OH)D concentration was measured by means of a direct, competitive chemiluminescence immunoassay. Associations were assessed using linear regression models. No significant association was seen between retrospective cod liver oil intake and hip BMD in old age. Current intake of aged men was also not associated with hip BMD, while aged women with daily intakes had z-scores on average 0.1 higher, compared with those with an intake of < once/week. Although significant, this difference is small, and its clinical relevance is questionable. Intake of aged participants was positively associated with serum 25(OH)D: individuals with intakes of < once/week, one to six time(s)/week and daily intake had concentrations of approximately 40, 50 and 60 nmol/l respectively (P for trend < 0.001).

  18. Osteoporotic-like effects of cadmium on bone mineral density and content in aged ovariectomized beagles

    SciTech Connect

    Sacco-Gibson, N.; Abrams, J.; Chaudhry, S.; Hurst, D.; Peterson, D.; Bhattacharyya, M.

    1992-12-31

    Our purpose was to evaluate the effects of ovariectomy in conjunction with cadmium (Cd) exposure on bone. Aged female beagles with {sup 45}Ca-labeled skeletons ovariectomized and exposed to Cd. Successive vertebral scans by dual photon absorptiometry monitored changes in bone mineral density (BMD) in each dog with time. Results showed that ovariectomy or Cd exposure alone caused significant decreases in BMD; ovariectomy with Cd exposure caused the greatest decrease. Ovariectomy alone did not decrease BMD in the distal end or mid-shaft of the tibia while BMD of the distal tibia decreased significantly due to Cd exposure alone. Combination treatment resulted in significant decreases in BMD of both tibial regions. At necropsy, tibiae, humeri, lumbar vertebrae and ribs were obtained for biochemical analysis. No group-to-group differences in bone weights (wet, dry, ash), in ash/dry ratios, or in long bone and vertebral Ca/dry or Ca/ash ratios were observed. Significantly higher total {sup 45}Ca content and {sup 45}Ca/dry and {sup 45}Ca/ash ratios were observed in long bones and vertebrae of OV- and OV+ groups. In contrast, intact ribs showed significantly decreased Ca/dry and Ca/ash ratios compared to the SO-group. Quartered ribs demonstrated regional responses to specific treatment; decreases in total Ca content were greatest in the mid-rib region ({minus}36 to {minus}46%). Results suggest that in the aged female beagle, bone mineral loss associated with estrogen depletion is not only related to bone type (trabecular versus cortical) but also to bone Ca pools. Our results also suggest that a regional heterogeneity of bone plays a role in responsiveness to ovariectomy and Cd exposure. These aspects suggest that Cd is an exogenous factor affecting bone mineral loss independently of estrogen depletion. However, estrogen depletion primes bone for responsiveness to Cd-induced bone mineral loss.

  19. The effect of mineral dust and soot aerosols on ice microphysics near the foothills of the Himalayas: A numerical investigation

    NASA Astrophysics Data System (ADS)

    Hazra, Anupam; Padmakumari, B.; Maheskumar, R. S.; Chen, Jen-Ping

    2016-05-01

    This study investigates the influence of different ice nuclei (IN) species and their number concentrations on cloud ice production. The numerical simulation with different species of ice nuclei is investigated using an explicit bulk-water microphysical scheme in a Mesoscale Meteorological Model version 5 (MM5). The species dependent ice nucleation parameterization that is based on the classical nucleation theory has been implemented into the model. The IN species considered include dust and soot with two different concentrations (Low and High). The simulated cloud microphysical properties like droplet number concentration and droplet effective radii as well as macro-properties (equivalent potential temperature and relative humidity) are comparable with aircraft observations. When higher dust IN concentrations are considered, the simulation results showed good agreement with the cloud ice and cloud water mixing ratio from aircraft measurements during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX) and Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. Relative importance of IN species is shown as compared to the homogeneous freezing nucleation process. The tendency of cloud ice production rates is also analyzed and found that dust IN is more efficient in producing cloud ice when compared to soot IN. The dust IN with high concentration can produce more surface precipitation than soot IN at the same concentration. This study highlights the need to improve the ice nucleation parameterization in numerical models.

  20. Gastric cancer and coal mine dust exposure. A case-control study

    SciTech Connect

    Ames, R.G.

    1983-10-01

    Based on evidence that coal miners have elevated gastric cancer mortality rates, a case-control study was developed to assess the gastric cancer risk of coal mine dust exposure. Forty-six cases of US white male gastric cancer deaths from NIOSH coal miner cohorts were individually matched by age to controls. From these data we show that a statistically elevated gastric cancer risk exists for miners who have prolonged exposure to coal mine dust and prolonged exposure to cigarette smoke. Coal workers' pneumoconiosis, a disease defined in terms of coal dust deposition in the lungs, was not found to be a gastric cancer risk.

  1. Association between Homocysteine and Bone Mineral Density according to Age and Sex in Healthy Adults

    PubMed Central

    Kim, Joo Il; Moon, Ji Hyun; Chung, Hye Won; Kong, Mi Hee

    2016-01-01

    Background There are several studies about the relationship between serum homocysteine levels and bone mineral density (BMD), but the results are varied, and the studies are limited in Korea. In our study, the relationship between serum homocysteine levels and BMD by part according to age and sex is investigated. Methods From March 2012 to July 2015, the 3,337 healthy adults who took a medical examination were recruited. Subjects filled in the self-recording type questionnaire and physical examination, blood test, BMD of lumbar spine and femur were measured. After sorting by aging (≤49 year old, 50-59 year old, ≥60 year old) and sex, the results were adjusted with age and body mass index (BMI) and the relationship between serum homocysteine levels and BMD by lumbar spine and femur was analyzed by multiple regression analysis. Results As results of analysis, with the adjustment with age and BMI, all age groups of men had no significant relationship between log-converted serum homocysteine levels and BMD. In women aged under 50, there were significantly negative relationships at lumbar spine (β=-0.028, P=0.038), femur neck (β=-0.062, P=0.001), and total hip (β=-0.076, P<0.001), but there was no significant relationship in other age groups (50-59 year old and ≥60 year old). Conclusions As the serum homocysteine levels increased in women aged under 50, BMD of the lumbar spine and femur decreased, and correlations between homocysteine and BMD were different by sex and age. PMID:27622176

  2. Association between Homocysteine and Bone Mineral Density according to Age and Sex in Healthy Adults

    PubMed Central

    Kim, Joo Il; Moon, Ji Hyun; Chung, Hye Won; Kong, Mi Hee

    2016-01-01

    Background There are several studies about the relationship between serum homocysteine levels and bone mineral density (BMD), but the results are varied, and the studies are limited in Korea. In our study, the relationship between serum homocysteine levels and BMD by part according to age and sex is investigated. Methods From March 2012 to July 2015, the 3,337 healthy adults who took a medical examination were recruited. Subjects filled in the self-recording type questionnaire and physical examination, blood test, BMD of lumbar spine and femur were measured. After sorting by aging (≤49 year old, 50-59 year old, ≥60 year old) and sex, the results were adjusted with age and body mass index (BMI) and the relationship between serum homocysteine levels and BMD by lumbar spine and femur was analyzed by multiple regression analysis. Results As results of analysis, with the adjustment with age and BMI, all age groups of men had no significant relationship between log-converted serum homocysteine levels and BMD. In women aged under 50, there were significantly negative relationships at lumbar spine (β=-0.028, P=0.038), femur neck (β=-0.062, P=0.001), and total hip (β=-0.076, P<0.001), but there was no significant relationship in other age groups (50-59 year old and ≥60 year old). Conclusions As the serum homocysteine levels increased in women aged under 50, BMD of the lumbar spine and femur decreased, and correlations between homocysteine and BMD were different by sex and age.

  3. CHARACTERIZING ULTRAVIOLET AND INFRARED OBSERVATIONAL PROPERTIES FOR GALAXIES. I. INFLUENCES OF DUST ATTENUATION AND STELLAR POPULATION AGE

    SciTech Connect

    Mao Yewei; Kong Xu; Kennicutt, Robert C. Jr.; Hao, Cai-Na; Zhou Xu E-mail: xkong@ustc.edu.cn

    2012-09-20

    The correlation between infrared-to-ultraviolet luminosity ratio and ultraviolet color (or ultraviolet spectral slope), i.e., the IRX-UV (or IRX-{beta}) relation, found in studies of starburst galaxies is a prevalent recipe for correcting extragalactic dust attenuation. Considerable dispersion in this relation discovered for normal galaxies, however, complicates its usability. In order to investigate the cause of the dispersion and to have a better understanding of the nature of the IRX-UV relation, in this paper, we select five nearby spiral galaxies, and perform spatially resolved studies on each of the galaxies, with a combination of ultraviolet and infrared imaging data. We measure all positions within each galaxy and divide the extracted regions into young and evolved stellar populations. By means of this approach, we attempt to discover separate effects of dust attenuation and stellar population age on the IRX-UV relation for individual galaxies. In this work, in addition to dust attenuation, stellar population age is interpreted to be another parameter in the IRX-UV function, and the diversity of star formation histories is suggested to disperse the age effects. At the same time, strong evidence shows the need for more parameters in the interpretation of observational data, such as variations in attenuation/extinction law. Fractional contributions of different components to the integrated luminosities of the galaxies suggest that the integrated measurements of these galaxies, which comprise different populations, would weaken the effect of the age parameter on IRX-UV diagrams. The dependence of the IRX-UV relation on luminosity and radial distance in galaxies presents weak trends, which offers an implication of selective effects. The two-dimensional maps of the UV color and the infrared-to-ultraviolet ratio are displayed and show a disparity in the spatial distributions between the two galaxy parameters, which offers a spatial interpretation of the scatter

  4. Mortality from stomach cancer in Ontario miners.

    PubMed Central

    Kusiak, R A; Ritchie, A C; Springer, J; Muller, J

    1993-01-01

    An excess of mortality from stomach cancer has been found in Ontario gold miners (observed (obs) 104, standardised mortality ratio (SMR) 152, 95% confidence interval (95% CI) 125-185) and no excess of stomach cancer could be detected in other miners in Ontario (obs 74, SMR 102, 95% CI 80-128). The excess of stomach cancer appeared five to 19 years after the miners began gold mining in Ontario. In that interval, similar patterns of excess mortality from stomach cancer were found in miners born in north America (obs 14, SMR 268, CI 147-450) and in miners born outside north America (obs 12, SMR 280, 95% CI 145-489). Twenty or more years after the miners began mining gold, an excess of mortality from stomach cancer was found in gold miners born outside of north American (obs 41, SMR 160, 95% CI 115-218) but not in gold miners born in north America (obs 37, SMR 113, 95% CI 80-156). The excess of stomach cancer in gold miners under the age of 60 (obs 45, SMR 167, 95% CI 122-223) seems larger than the excess in gold miners between the ages of 60 and 74 (obs 59, SMR 143, 95% CI 109-184). Exposures to arsenic, chromium, mineral fibre, diesel emissions, and aluminium powder were considered as possible explanations of the excess of stomach cancer in Ontario gold miners. Exposure to diesel emissions and aluminium powder was rejected as gold miners and uranium miners were exposed to both agents but an excess of stomach cancer was noted only in gold miners. The association between the excess of stomach cancer and the time since the miner began mining gold suggested that duration of exposure to dust in gold mines ought to be weighted according to the time since the exposure to dust occurred and that an appropriate time weighting function would be one in the interval five to 19 years after each year of exposure to dust and zero otherwise. A statistically significant association between the relative risk of mortality from stomach cancer and the time weighted duration of exposure to

  5. Effect of deproteination on bone mineral morphology: implications for biomaterials and aging.

    PubMed

    Carter, D H; Scully, A J; Heaton, D A; Young, M P J; Aaron, J E

    2002-09-01

    Bone mineral morphology is altered by processing and this is rarely considered when preparing bone as a bioimplant material. To examine the degree of transformation, a commercial, coarsely particulate bone mineral biomaterial produced by prolonged deproteination, defatting, dehydration, and heating (donor material) was compared with similar particles of human bone (recipient material) prepared optimally by low-temperature milling. The two powders were freeze-substituted and embedded without thawing in Lowicryl K4M before sectioning for transmission electron microscopy (TEM) (other aliquots were processed by traditional TEM methods). To maximize resolution, electron micrographs were image-enhanced by digitization and printed as negatives using a Polaroid Sprint Scan 45. In addition to their morphology, the particles were examined for antigenicity (specific by reference to fluorescein isothiocyanate [FITC]-conjugated fibronectin, and nonspecific by reference to general FITC-conjugated immunoglobulins). Results showed that the optimally prepared human bone fragments stained discretely for fibronectin with negligible background autofluorescence. In contrast, the bioimplant fragments stained extensively with this and any other FITC-conjugated antibody and, unlike fresh bone, it also autofluoresced a uniform yellow. This difference was also expressed structurally and, although the bioimplant mineral consisted of rhomboidal plates up to 200 nm across and 10 nm thick, the optimally prepared bone mineral was composed of numerous clusters of 5-nm-wide sinuous calcified filaments of variable density and indeterminate length (which became straight needles 50 nm long and 5 nm thick following traditional chemical TEM fixation/staining). It was concluded that the inorganic phase of bone is both morphologically and immunologically transmutable and that, in biomaterials, the transformation is apparently so great that a broad indigenous antigenicity is unmasked, increasing the

  6. Parameterizing ice nucleation ability of mineral dust particles in the deposition mode: Numerical investigations using large eddy simulation

    NASA Astrophysics Data System (ADS)

    Savre, J.; Ekman, A. M. L.; Svensson, G.; Tjernström, M.

    2013-05-01

    A parameterization for heterogeneous ice nucleation of dust particles in the deposition mode is proposed and implemented in a Large Eddy Simulation model. The approach based on Classical Nucleation Theory relies on the definition of contact angle PDFs based on experimental data to characterize nucleation ability of the aerosol population. A bin approach is used to discretize the contact angle PDFs in order to account for the fact that the most efficient ice nuclei will form ice crystals quickly leaving only the least efficient nuclei as simulation progresses. The nucleation scheme is evaluated against a single-layer mixed-phase cloud observed over Barrow during the ISDAC campaign. As a matter of fact, analysis of the data collected onboard the aircraft during flight 31 suggests that dust particles are most likely the dominant source of newly nucleated ice crystals, acting in the deposition mode.

  7. U-Pb isotope systematics and age of uranium mineralization, Midnite mine, Washington.

    USGS Publications Warehouse

    Ludwig, K. R.; Nash, J.T.; Naeser, C.W.

    1981-01-01

    Uranium ores at the Midnite mine, near Spokane, Washington, occur in phyllites and calcsilicates of the Proterozoic Togo Formation, near the margins of an anomalously uraniferous, porphyritic quartz monzonite of Late Cretaceous age. The present geometry of the ore zones is tabular, with the thickest zones above depressions in the pluton-country rock contact. Analyses of high-grade ores from the mine define a 207 Pb/ 204 Pb- 235 U/ 204 Pb isochron indicating an age of mineralization of 51.0 + or - 0.5 m.y. This age coincides with a time of regional volcanic activity (Sanpoil Volcanics), shallow intrusive activity, erosion, and faulting. U-Th-Pb isotopic ages of zircons from the porphyritic quartz monzonite in the mine indicate an age of about 75 m.y., hence the present orebodies were formed about 24 m.y. after its intrusion. The 51-m.y. time of mineralization probably represents a period of mobilization and redeposition of uranium by supergene ground waters, perhaps aided by mild heating and ground preparation and preserved by a capping of newly accumulated, impermeable volcanic rocks. It seems most likely that the initial concentration of uranium occurred about 75 m.y. ago, probably from relatively mild hydrothermal fluids in the contact-metamorphic aureole of the U-rich porphyritic quartz monzonite.Pitchblende, coffinitc, pyrite, marcasite, and hisingerite are the most common minerals in the uranium-bearing veinlets, with minor sphalerite and chalcopyrite. Coffinitc with associated marcasite is paragenetically later than pitchblende, though textural and isotopic evidence suggests no large difference in the times of pitchblende and colfinite formation.The U-Pb isotope systematics of total ores and of pitchblende-coffinite and pyrite-marcasite separates show that whereas open system behavior for U and Pb is essentially negligible for large (200-500 g) ore samples, Pb migration has occurred on a scale of 1 to 10 mm (out of pitchblende and coffinite and into pyrite

  8. 30 CFR 75.402 - Rock dusting.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting. All... content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces,...

  9. 30 CFR 75.402 - Rock dusting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting. All... content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces,...

  10. 30 CFR 75.402 - Rock dusting.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting. All... content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces,...

  11. 30 CFR 75.402 - Rock dusting.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting. All... content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces,...

  12. 30 CFR 75.402 - Rock dusting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock dusting. 75.402 Section 75.402 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Combustible Materials and Rock Dusting § 75.402 Rock dusting. All... content to propagate an explosion, shall be rock dusted to within 40 feet of all working faces,...

  13. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    NASA Astrophysics Data System (ADS)

    Solum, John G.; van der Pluijm, Ben A.; Peacor, Donald R.

    2005-09-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ˜40% in 1M d illite relative to protolith, whereas altered protolith in the damage zone is enriched ˜40% in illite-smectite relative to gouge and up to ˜50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/ 39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1M d) gouge illite (63±2 Ma) and illite-smectite in the damage zone (60±2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone.

  14. Neocrystallization, fabrics and age of clay minerals from an exposure of the Moab Fault, Utah

    USGS Publications Warehouse

    Solum, J.G.; van der Pluijm, B.A.; Peacor, D.R.

    2005-01-01

    Pronounced changes in clay mineral assemblages are preserved along the Moab Fault (Utah). Gouge is enriched up to ???40% in 1Md illite relative to protolith, whereas altered protolith in the damage zone is enriched ???40% in illite-smectite relative to gouge and up to ???50% relative to protolith. These mineralogical changes indicate that clay gouge is formed not solely through mechanical incorporation of protolith, but also through fault-related authigenesis. The timing of mineralization is determined using 40Ar/39Ar dating of size fractions of fault rocks with varying detrital and authigenic clay content. We applied Ar dating of illite-smectite samples, as well as a newer approach that uses illite polytypes. Our analysis yields overlapping, early Paleocene ages for neoformed (1Md) gouge illite (63??2 Ma) and illite-smectite in the damage zone (60??2 Ma), which are compatible with results elsewhere. These ages represent the latest period of major fault motion, and demonstrate that the fault fabrics are not the result of recent alteration. The clay fabrics in fault rocks are poorly developed, indicating that fluids were not confined to the fault zone by preferentially oriented clays; rather we propose that fluids in the illite-rich gouge were isolated by adjacent lower permeability, illite-smectite-bearing rocks in the damage zone. ?? 2005 Elsevier Ltd. All rights reserved.

  15. Comparative Study on Accelerated Thermal Ageing of Vegetable Insulating Oil-paperboard and Mineral Oil-paperboard

    NASA Astrophysics Data System (ADS)

    Zhou, Zhu-Jun; Hu, Ting; Cheng, Lin; Tian, Kai; Yang, Jun; Wang, Xuan; Fang, Fu-Xin; Kong, Hai-Yang; Qian, Hang

    2016-05-01

    To comparatively study the insulation ageing life of vegetable insulating oil-paperboard and mineral oil-paperboard, we conducted accelerated thermal ageing experiments at 170°C. Then according to the temperature rise of vegetable insulating oil transformer, we conducted accelerated thermal ageing experiments at 150°C for vegetable insulating oil-paperboard and at 140°C for mineral oil-paperboard. The appearance, polymerization degree, and SEM microstructure of the paperboard after different ageing experiments were comparative analyzed. The results show that after the oil-paperboard system is accelerated ageing for 1 000 h at 170°C, that is equivalent to 20 years natural ageing, the structure of paperboard in vegetable insulating oil is damaged severely, which indicates that the lifetime of transformer are in the late stage; while the structure of paperboard in mineral oil maintain complete, and the polymerization degree is still above 500, which indicate that the lifetime of transformer are in the middle stage. The accelerated ageing rate of the vegetable insulating oil-paperboard system at 150°C is slower than that of the mineral oil-paperboard system, which indicates that the lifetime of the vegetable insulating oil-paperboard is longer than that of the mineral oil-paperboard.

  16. Pneumoconiosis from Agricultural Dust Exposure among Young California Farmworkers

    PubMed Central

    Schenker, Marc B.; Pinkerton, Kent E.; Mitchell, Diane; Vallyathan, Val; Elvine-Kreis, Brenda; Green, Francis H.Y.

    2009-01-01

    Background Agricultural workers are exposed to airborne pollutants, including organic and inorganic (mineral) dusts. Objectives Lung autopsy specimens from consecutive coroner’s cases of Hispanic males in Fresno County, California, (n = 112) were obtained to determine whether mineral dust exposure in agricultural work leads to pneumoconiosis. Methods The left lung was fixed by inflation. We evaluated airway and parenchymal pathology using standardized diagnostic criteria and semiquantitative grading schemata, including the grading of small airways for fibrosis and birefringent mineral dust particles. We analyzed lung dust burden on a subset of 37 lungs following bleach digestion, using scanning electron microscopy (SEM), X-ray spectrometry (XRS) and image analysis, and by X-ray diffraction for crystalline silica (CSi). Farmworkers comprised 51.5% and nonfarmworkers 48.5% of the samples. Results Proximal airways demonstrated little mineral dust accumulation, but membranous and respiratory bronchioles had wall thickening, remodeling, and inflammation associated with carbonaceous and mineral dust deposition. These changes were independently associated with agricultural work, cigarette smoking, and increased age. Mineral dust small airways disease, pneumoconiosis (macules and nodules), and pathologic changes consistent with chronic bronchitis, emphysema, and interstitial fibrosis predominated in farmworkers compared with nonfarmworkers. CSi, determined gravimetrically, and aluminum silicate particles, determined by SEM/XRS, were increased in the lungs of farmworkers compared with nonfarmworkers and were significantly (p < 0.05) associated with small airway disease and pneumoconiosis. Conclusion Mineral dust exposure is associated with increased small airway disease and pneumoconiosis among California farmworkers; however, the clinical significance and natural history of these changes remains to be determined. PMID:19590695

  17. On the effect of dust particles on global cloud condensation nuclei and cloud droplet number

    NASA Astrophysics Data System (ADS)

    Karydis, V. A.; Kumar, P.; Barahona, D.; Sokolik, I. N.; Nenes, A.

    2011-12-01

    Aerosol-cloud interaction studies to date consider aerosol with a substantial fraction of soluble material as the sole source of cloud condensation nuclei (CCN). Emerging evidence suggests that mineral dust can act as good CCN through water adsorption onto the surface of particles. This study provides a first assessment of the contribution of insoluble dust to global CCN and cloud droplet number concentration (CDNC). Simulations are carried out with the NASA Global Modeling Initiative chemical transport model with an online aerosol simulation, considering emissions from fossil fuel, biomass burning, marine, and dust sources. CDNC is calculated online and explicitly considers the competition of soluble and insoluble CCN for water vapor. The predicted annual average contribution of insoluble mineral dust to CCN and CDNC in cloud-forming areas is up to 40 and 23.8%, respectively. Sensitivity tests suggest that uncertainties in dust size distribution and water adsorption parameters modulate the contribution of mineral dust to CDNC by 23 and 56%, respectively. Coating of dust by hygroscopic salts during the atmospheric aging causes a twofold enhancement of the dust contribution to CCN; the aged dust, however, can substantially deplete in-cloud supersaturation during the initial stages of cloud formation and can eventually reduce CDNC. Considering the hydrophilicity from adsorption and hygroscopicity from solute is required to comprehensively capture the dust-warm cloud interactions. The framework presented here addresses this need and can be easily integrated in atmospheric models.

  18. On the Effect of Dust Particles on Global Cloud Condensation Nuclei and Cloud Droplet Number

    NASA Technical Reports Server (NTRS)

    Karydis, V. A.; Kumar, P.; Barahona, D.; Sokolik, I. N.; Nenes, A.

    2011-01-01

    Aerosol-cloud interaction studies to date consider aerosol with a substantial fraction of soluble material as the sole source of cloud condensation nuclei (CCN). Emerging evidence suggests that mineral dust can act as good CCN through water adsorption onto the surface of particles. This study provides a first assessment of the contribution of insoluble dust to global CCN and cloud droplet number concentration (CDNC). Simulations are carried out with the NASA Global Modeling Initiative chemical transport model with an online aerosol simulation, considering emissions from fossil fuel, biomass burning, marine, and dust sources. CDNC is calculated online and explicitly considers the competition of soluble and insoluble CCN for water vapor. The predicted annual average contribution of insoluble mineral dust to CCN and CDNC in cloud-forming areas is up to 40 and 23.8%, respectively. Sensitivity tests suggest that uncertainties in dust size distribution and water adsorption parameters modulate the contribution of mineral dust to CDNC by 23 and 56%, respectively. Coating of dust by hygroscopic salts during the atmospheric aging causes a twofold enhancement of the dust contribution to CCN; the aged dust, however, can substantially deplete in-cloud supersaturation during the initial stages of cloud formation and can eventually reduce CDNC. Considering the hydrophilicity from adsorption and hygroscopicity from solute is required to comprehensively capture the dust-warm cloud interactions. The framework presented here addresses this need and can be easily integrated in atmospheric models.

  19. Age-related decrements in bone mineral density in women over 65

    NASA Technical Reports Server (NTRS)

    Steiger, P.; Cummings, S. R.; Black, D. M.; Spencer, N. E.; Genant, H. K.

    1992-01-01

    Age-related changes in bone density contribute to the risk of fractures. To describe the relationship between age and bone mass in elderly women, we studied a large cohort of women over age 65 years who were recruited from population-based lists in four cities in the United States. Bone density in g/cm2 was measured by single-photon absorptiometry (SPA) and dual x-ray absorptiometry (DXA) at the distal and proximal radius, the calcaneus, the lumbar spine, and the proximal femur. Centralized data collection was used to control data quality and consistency. We found a strong inverse relationship between bone density and age for most sites. Decrements in bone density between women aged 65-69 years and women 85 years and older exceeded 16% in all regions except the spine, where the difference between the two age groups was 6%. Ward's triangle and the calcaneus exhibited the largest decrements, with 26 and 21%, respectively. The estimates of annual changes in bone mineral density by linear regression at sites other than the spine ranged from -0.82% at the femoral neck and trochanter to -1.30% at Ward's triangle. Correlations between the different regions ranged from r = 0.51 between the proximal radius and Ward's triangle to r = 0.66 between the distal radius and calcaneus. We conclude that the inverse relationship between age and bone mass measured by absorptiometry techniques in white women continues into the ninth decade of life. The relationship is strongest for bone density of Ward's triangle and the calcaneus and weakest for the spine.

  20. The Paleozoic Dust Bowl: Dust Deposition in Tropical Western Pangaea (Midcontinent U.S.) at the Terminus of the Late Paleozoic Ice Age

    NASA Astrophysics Data System (ADS)

    Soreghan, G. S.; Heavens, N. G.; Benison, K. C.; Soreghan, M. J.; Mahowald, N. M.; Foster, T.; Zambito, J.; Sweet, A.; Kane, M.

    2012-12-01

    Atmospheric dust is well recognized and studied as both an archive and agent of climate change in Earth's relatively recent past. Archives of past dust include loess deposits and dust recovered from ocean- and ice-cores. Dust remains poorly known in Earth's past prior to the Cenozoic, but is increasingly recognized in the form of paleo-loess deposits, and (epeiric) marine strata that accumulated isolated from fluvio-deltaic influx. Here, we report on the growing recognition of voluminous dust deposits preserved in the Permian record of the U.S. Midcontinent (western tropical Pangaea). Fine-grained redbeds predominate in Permian strata throughout the U.S. Midcontinent, but notably in a swath extending from Oklahoma through South Dakota. These units consist predominantly of red mudstone and siltstone in commonly massive units, but sedimentary structures and bedding that signal aqueous processes (e.g. laminations, ripples) have led most to infer deltaic or tidal deposition. The absence of channel systems to deliver the sediment, as well as the predominantly massive and laterally continuous character and the uniform fine grain size signal wind transport, implying that these units record sustained dust deposition overprinted at times by sub-aqueous deposition in lakes, including ephemeral saline and acid lakes that led to evaporite cementation. Detrital zircon geochronology indicates that much of the dust originated in the relatively distant Appalachian-Ouachita orogenic systems, which formed part of the central Pangaean mountains (CPM), the collisional zone that sutured the supercontinent. Within the Anadarko basin of Oklahoma, Permian redbeds record >2 km of predominantly dust deposition, some of the thickest dust deposits yet documented in Earth's record. Yet the tropical setting is remarkably non-uniformitarian, as much Quaternary loess occurs in mid- to high-latitude regions, commonly linked to glacial genesis. We are currently investigating with both data and

  1. Ovariectomy-induced changes in aged beagles: Histomorphometry and mineral content of the rib

    SciTech Connect

    Wilson, A.K.; Bhattacharyya, M.H.; Hurst, D.; Miller, S.; Sacco-Gibson, N.

    1997-08-01

    The effects of ovariectomy on the aged beagle skeleton were studied by histomorphometric analysis of the cortical bone in sequential rib biopsies. Biopsies were taken from each ovariectomized (OV) or sham-operated (SO) dog at the time of surgery and at 1, 4, and 8.5 months after surgery. Tetracycline, calcein, and xylenol orange, respectively, were administered by a fluorochrome labeling procedure (2d-10d-2d) just prior to each postoperative biopsy to provide markers of bone formation. Analysis of sequential biopsies provided a means to follow the response to ovariectomy over time and compare each animal against its own baseline. Examination of sequential biopsies indicated that cortical porosity increased by the fourth month after ovariectomy and remained high at 8.5 months. Ovariectomy did not influence histomorphometric indices at one month after surgery, but substantial differences were observed at later times. Ovariectomy stimulated a transient increase in bone formation and was increased six-fold over that of SO dogs at four months. Ribs were also analyzed for mineral content at necropsy. The rib was heterogeneous along its length for calcium content and concentration. In the midrib where biopsies for histomorphometric analysis were taken, ovariectomy induced a decrease in mass and mineral content; total calcium was decreased by approximately 31%. These data demonstrate that the rib cortical bone is a responsive site for the effects of ovariectomy in female dogs.

  2. Assemblage characteristics of clay minerals and its implications to evolution of eolian dust input to the Parece Vela Basin since 1.95 Ma

    NASA Astrophysics Data System (ADS)

    Ming, Jie; Li, Anchun; Huang, Jie; Wan, Shiming; Meng, Qingyong; Jiang, Fuqing; Yan, Wenwen

    2014-01-01

    To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investigated using paleogeomagnetic dating and X-ray diffraction. The assemblage of the core mainly consisted of smectite (˜46%) and illite (˜40%), with some chlorite (˜10%) and kaolinite (˜4%). Analysis of the provenance of these minerals suggested that smectite was mainly derived from volcanic rocks of the Mariana Arc, while illite, chlorite, and kaolinite were mainly transported as eolian dust by the East Asian monsoon from central Asia. We used the ratio of (illite+chlorite+kaolinite)/smectite as a proxy for Asian eolian input to the Parece Vela Basin since 1.95 Ma. This ratio followed glacial and interglacial cycles and was consistent with the intensity of the East Asian monsoon and aridity of central Asia since 1.95 Ma. The changes of the ratio reflected three different stages of the East Asian monsoon and provenance climate.

  3. Adynamic Bone Decreases Bone Toughness During Aging by Affecting Mineral and Matrix.

    PubMed

    Ng, Adeline H; Omelon, Sidney; Variola, Fabio; Allo, Bedilu; Willett, Thomas L; Alman, Benjamin A; Grynpas, Marc D

    2016-02-01

    Adynamic bone is the most frequent type of bone lesion in patients with chronic kidney disease; long-term use of antiresorptive therapy may also lead to the adynamic bone condition. The hallmark of adynamic bone is a loss of bone turnover, and a major clinical concern of adynamic bone is diminished bone quality and an increase in fracture risk. Our current study aims to investigate how bone quality changes with age in our previously established mouse model of adynamic bone. Young and old mice (4 months old and 16 months old, respectively) were used in this study. Col2.3Δtk (DTK) mice were treated with ganciclovir and pamidronate to create the adynamic bone condition. Bone quality was evaluated using established techniques including bone histomorphometry, microcomputed tomography, quantitative backscattered electron imaging, and biomechanical testing. Changes in mineral and matrix properties were examined by powder X-ray diffraction and Raman spectroscopy. Aging controls had a natural decline in bone formation and resorption with a corresponding deterioration in trabecular bone structure. Bone turnover was severely blunted at all ages in adynamic animals, which preserved trabecular bone loss normally associated with aging. However, the preservation of trabecular bone mass and structure in old adynamic mice did not rescue deterioration of bone mechanical properties. There was also a decrease in cortical bone toughness in old adynamic mice that was accompanied by a more mature collagen matrix and longer bone crystals. Little is known about the effects of metabolic bone disease on bone fracture resistance. We observed an age-related decrease in bone toughness that was worsened by the adynamic condition, and this decrease may be due to material level changes at the tissue level. Our mouse model may be useful in the investigation of the mechanisms involved in fractures occurring in elderly patients on antiresorptive therapy who have very low bone turnover. PMID:26332924

  4. Mineral content of longissimus dorsi thoracis from water buffalo and Zebu-influenced cattle at four comparative ages.

    PubMed

    Giuffrida-Mendoza, M; Arenas de Moreno, L; Uzcátegui-Bracho, S; Rincón-Villalobos, G; Huerta-Leidenz, N

    2007-03-01

    The longissimus dorsi thoracis (LDT) of 64 water buffalo and 68 Zebu-influenced cattle was used to determine the mineral content variation (mg/100g of fresh tissue) according to species, age (7, 17, 19 and 24 months-of-age, MOA) and gender (steers and bulls). Buffalo LDT had higher concentrations of K, Mn, Fe, Zn and Cu at weaning (P<0.05). Phosphorous content was higher (P<0.05) at post-weaning ages. Mineral profile was affected by age without clear trends; the Na and K contents increased at 24 MOA. The age×species, age×gender and species×gender interactions affected (P<0.05) Fe content that ranged from 1.74 to 2.56mg/100g fresh tissue. Meat from both species contributes with more of 25% of K, P, Fe and Zn of the daily requirement for an adult.

  5. Age-related ransparent root dentin: mineral concentration,crystallite size and mechanical properties

    SciTech Connect

    Kinney, John H.; Nalla, Ravi K.; Pople, John A.; Breunig, Tom M.; Ritchie, Robert O.

    2004-12-29

    Many fractures occur in teeth that have been altered, forexample restored or endodontically repaired. It is therefore essential toevaluate the structure and mechanical properties of these altereddentins. One such altered form of dentin is transparent (sometimes calledsclerotic) dentin, which forms gradually with aging. The present studyfocuses on differences in the structure and mechanical properties ofnormal versus transparent dentin. The mineral concentration, as measuredby X-ray computed microtomography, was signifcantly higher in transparentdentin, the elevated concentration being consistent with the closure ofthe tubule lumens. Crystallite size, as measured by small angle X-rayscattering, was slightly smaller in transparent dentin, although theimportance of this ending requires further study. The elastic propertieswere unchanged by transparency; however, transparent dentin, unlikenormal dentin, exhibited almost no yielding before failure. In addition,the fracture toughness was lowered by roughly 20 percent while thefatigue lifetime was deleteriously affected at high stress levels. Theseresults are discussed in terms of the altered microstructure oftransparent dentin.

  6. SHRIMP and 40Ar/39Ar age constraints for timing of plutonism and mineralization in the Boulder batholith

    USGS Publications Warehouse

    Lund, K.D.; Aleinikoff, John N.; Kunk, Michael J.; Unruh, Dan M.; Zeihen, G.D.; Hodges, W.C.; du Bray, Edward A.; O'Neill, J Michael

    2002-01-01

    The 66 Ma age for the quartz monzodiorite of Boulder Baldy and consideration of previous dating studies in the region indicate that small ca. 66 Ma plutonic systems may be common in the Boulder batholith region and especially to the east. The approximately 64 Ma porphyry copper systems at Butte and gold mineralization at Miller Mountain are indicative of regionally important mineralizing systems of this age in the Boulder batholith region. Resolution of the age and probable magmatic source of the Butte pre-Main Stage porphyry copper-molybdenum system and of the silver-rich polymetallic quartz vein systems in the northern part of the Boulder batholith documents that these deposits formed from two discrete periods of hydrothermal mineralization related to two discrete magmatic events.

  7. Predictors of Bone Mineral Density in African-American and Caucasian College-Aged Women

    PubMed Central

    Johnson, Andrea K.; Ford, M. Allison; Jones, Tamekia L.; Nahar, Vinayak K.; Hallam, Jeffrey S.

    2015-01-01

    Background: Research regarding risk factors and prevalence of low bone mineral density (BMD) among African-American and Caucasian college-aged women are limited. The objective of this cross-sectional study was to determine if selected predictors of BMD in African-American and Caucasian college-aged women differ by race. Methods: A total of 101 local African-American (n=50) and Caucasian (n=51) females, ages 18 to 30 years, were in this study. All data were collected in the Bone Density and Body Composition Laboratory. BMD was measured using DXA technology. Race, family history of osteoporosis, BMI, current physical activity, osteoporosis knowledge, length of time on oral contraceptives, age at menarche and calcium intake were included in the multiple regression analyses with spinal and femoral BMD as dependent variables. Results: Overall, 38.6% had low spinal BMD and 7.9% had low femoral BMD. BMI (β=0.073, R2 = .148, P = .001, 95% CI [0.030, 0.116]) and current physical activity (β=0.071, R2 = .148, P = .017, 95% CI [0.013, 0.129]) were the only variables that were statistically significant in predicting spinal BMD. BMI (β=0.056, R2 = .13, P = .010, 95% CI [0.014, 0.098]) and current physical activ-ity (β=0.078, R2 = .13, P = .007, 95% CI [0.022, 0.134]) were also the only varia-bles that were statistically significant in predicting femoral BMD. Race was not a significant predictor of spinal or femoral BMD. Conclusion: It is imperative for both African-American and Caucasian women to engage in osteoporosis-preventive behaviors. PMID:26000242

  8. Association of Renal Function and Menopausal Status with Bone Mineral Density in Middle-aged Women

    PubMed Central

    Sheng, Yueh-Hsuan; Chen, Jen-Hau; Chiou, Jeng-Min; Tsai, Keh-Sung; Lee, Yue-Yuan; Tsao, Chwen-Keng; Chen, Yen-Ching

    2015-01-01

    The association between mild renal dysfunction and bone mineral density (BMD) has not been fully explored. It is also unclear how menopausal status and the use of Chinese herb affect this association. This is a cross-sectional study that included a total of 1,419 women aged 40 to 55 years old who were recruited from the MJ Health Management Institution in Taiwan between 2009 and 2010. Spinal BMD was assessed by dual-energy X-ray absorptiometry. Renal function was assessed using estimated glomerular filtration rate (eGFR) and creatinine clearance rate (CCr). The multivariable logistic regression and general linear models were employed to assess the association between renal function and BMD. Stratification analyses were performed by menopausal status and use of Chinese herbs. Low CCr levels were significantly associated with low BMD [adjusted odds ratio (AOR) = 1.48, 95% confidence interval (CI) = 1.15–1.90]. This association was observed in premenopausal women (AOR = 1.43, 95% CI = 1.07–1.92) and in women not taking Chinese herbs (AOR = 1.48, 95% CI = 1.14–1.94). CCr is a better predictor for low BMD in middle-aged women. Menopausal status and the use of Chinese herbs also affected this association. PMID:26459876

  9. Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8-13 μm) and visible aerosol optical thickness measurements: 2. Mineral aerosol mixture analyses

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.

    2009-07-01

    The mineral aerosol mixture composition for the March 2006 Saharan dust storm is assessed in this paper on the basis of the analysis of visible to near-infrared (VIS-NIR) and infrared (IR) aerosol optical thickness (AOT) spectra obtained during the Portable Infrared Aerosol Transmission Experiment (PIRATE). The AOT spectra from 8 to 13 μm were determined using column-integrated solar transmission measurements using a Fourier transform infrared spectrometer. To determine the mineralogy and mixture composition of the dust, we determined the expected mineralogy of dust from the Algerian source region in a dust storm environment. Then we computed the modeled VIS-IR AOT spectra using Mie theory for external and internal mixtures. We compared the modeled VIS-NIR AOT spectra and derived index of refraction and single-scattering albedo with the measured values from AERONET and compared the modeled IR AOT spectra with the values from our IR measurements. The fit between the measured and modeled values was best when we used an extinction resonance correction to the Mie theory results to better account for the exact wavelengths and shapes of some of the AOT peaks for mineral particles. The mineralogy and mixture composition of the best dust model includes external mixtures, internal mixtures, and mineralogy dominated by quartz, illite, and calcite. The modeled mean radius was determined, and several modes were computed in agreement with AERONET results.

  10. Tracing the pathway of compositional changes in bone mineral with age: Preliminary study of bioapatite aging in hypermineralized dolphin’s bulla

    PubMed Central

    Li, Zhen; Pasteris, Jill D.

    2014-01-01

    Background Studies of mineral compositional effects during bone aging are complicated by the presence of collagen. Methods Hypermineralized bullae of Atlantic bottlenose dolphins of < 3 months, 2.5 years, and 20 years underwent micrometer-scale point analysis by Raman spectroscopy and electron microprobe in addition to bulk analysis for carbon. Results Bulla central areas have a mineral content of ~96 wt.% and 9–10 wt.% carbonate in their bioapatite, which is ~2 wt.% more than edge areas. Ca/P atomic ratios (~1.8) and concentrations of Mg, S, and other minor/trace elements are almost constant in central areas over time. Maturity brings greater over-all homogeneity in mineral content, stoichiometry, and morphology throughout central and edge areas of the bullae. During aging, edge areas become less porous, whereas the concentration of organics in the edge is reduced. Enhancement of coupled substitutions of CO32− for PO43− and Na for Ca during aging increases carbonate content up to ~10 wt.% in the adult bulla. Conclusions 1) Changes in physical properties during aging did not occur simultaneously with changes in chemical properties of the bone mineral. 2) Compositional changes in bone mineral were minor during the neonatal to sub-adult stage, but significant during later maturity. 3) Na and CO3 concentrations covary in a 1:1 molar proportion during aging. 4) The mineral’s crystallinity did not decrease as CO3 concentration increased during aging. General Significance Hypermineralized dolphin’s bulla, due to extreme depletion in collagen, is an ideal material for investigating mineralogical changes in bioapatite during bone aging. PMID:24650888

  11. A new thermal gradient ice nucleation diffusion chamber instrument: design, development and first results using Saharan mineral dust

    SciTech Connect

    Kulkarni, Gourihar R.; Dobbie, Steven; McQuaid, Jim

    2009-06-11

    A new Thermal Gradient ice nucleation Diffusion Chamber (TGDC) capable of investigating ice nucleation efficiency of atmospherically important aerosols, termed Ice Nuclei (IN), has been designed, constructed and validated. The TGDC can produce a range of supersaturations with respect to ice (SSi) over the temperature range of -10 to -34°C for sufficiently long time needed to observe the nucleation by the particles. The aerosol particles under examination were supported on a Teflon substrate and nucleation events observed using digital photography. The TGDC consists of two ice coated plates to which a thermal gradient is applied to produce the range of SSi. The ability to understand time-related ice nucleation event information and to perform experiments at different temperatures and SSi conditions for different IN without changing the thermal gradient makes the TGDC a unique ice nucleation chamber. The SSi and temperature conditions of the experimental system are validated by observing (NH4)2SO4 deliquescence and the results are in good agreement with the literature data. The design details of the TGDC along with the experimental set-up, the experimental procedure and its usefulness in understanding ice nucleation processes of dust particles are presented. The ice nucleation investigations using different particles are needed to better quantify the role of ice formation in the atmosphere.

  12. The adsorption of fungal ice-nucleating proteins on mineral dusts: a terrestrial reservoir of atmospheric ice-nucleating particles

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Daniel; Murray, Benjamin J.; Ross, James F.; Webb, Michael E.

    2016-06-01

    The occurrence of ice-nucleating particles (INPs) in our atmosphere has a profound impact on the properties and lifetime of supercooled clouds. To date, the identities, sources and abundances of particles capable of nucleating ice at relatively low supercoolings (T > -15 °C) remain enigmatic. While biomolecules such as proteins and carbohydrates have been implicated as important high-temperature INPs, the lack of knowledge on the environmental fates of these species makes it difficult to assess their potential atmospheric impacts. Here we show that such nanoscale ice-nucleating proteins from a common soil-borne fungus (Fusarium avenaceum) preferentially bind to and confer their ice-nucleating properties to kaolinite. The ice-nucleating activity of the proteinaceous INPs is unaffected by adsorption to the clay, and once bound the proteins do not readily desorb, retaining much of the activity even after multiple washings with pure water. The atmospheric implications of the finding that biological residues can confer their ice-nucleating ability to dust particles are discussed.

  13. Selenium Status Is Positively Associated with Bone Mineral Density in Healthy Aging European Men

    PubMed Central

    Beukhof, Carolien M.; Medici, Marco; van den Beld, Annewieke W.; Hollenbach, Birgit; Hoeg, Antonia; Visser, W. Edward; de Herder, Wouter W.; Visser, Theo J.; Schomburg, Lutz; Peeters, Robin P.

    2016-01-01

    Objective It is still a matter of debate if subtle changes in selenium (Se) status affect thyroid function tests (TFTs) and bone mineral density (BMD). This is particularly relevant for the elderly, whose nutritional status is more vulnerable. Design and Methods We investigated Se status in a cohort of 387 healthy elderly men (median age 77 yrs; inter quartile range 75–80 yrs) in relation to TFTs and BMD. Se status was determined by measuring both plasma selenoprotein P (SePP) and Se. Results The overall Se status in our population was low normal with only 0.5% (2/387) of subjects meeting the criteria for Se deficiency. SePP and Se levels were not associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), triiodothyronine (T3) or reverse triiodothyronine (rT3) levels. The T3/T4 and T3/rT3 ratios, reflecting peripheral metabolism of thyroid hormone, were not associated with Se status either. SePP and Se were positively associated with total BMD and femoral trochanter BMD. Se, but not SePP, was positively associated with femoral neck and ward's BMD. Multivariate linear analyses showed that these associations remain statistically significant in a model including TSH, FT4, body mass index, physical performance score, age, smoking, diabetes mellitus and number of medication use. Conclusion Our study demonstrates that Se status, within the normal European marginally supplied range, is positively associated with BMD in healthy aging men, independent of thyroid function. Thyroid function tests appear unaffected by Se status in this population. PMID:27055238

  14. 40Ar/39Ar age and chemistry of manganese mineralization in the Moab and Lisbon fault systems, southeastern Utah

    NASA Astrophysics Data System (ADS)

    Chan, Marjorie A.; Parry, William T.; Petersen, Erich U.; Hall, Chris M.

    2001-04-01

    Diagenetic iron and manganese mineralization is associated with the Moab and Lisbon faults and is an important indicator of fluid flow in Jurassic Navajo Sandstone of southeastern Utah. Reducing brines originating from the Pennsylvanian Paradox Formation (with or without hydrocarbons) mobilized disseminated iron and manganese in the Jurassic sandstones and mixed with shallow, oxygenated groundwater to precipitate both iron and manganese mineralization. Mineralization consists of colliform and concretionary hematite, pyrolusite, and cryptomelane-hollandite that contains 1.33 2.12 wt% K. The 40Ar/39Ar dating of vacuum-encapsulated cryptomelane yields age estimates of 25 20 Ma, indicating mineralization coincident with either a Colorado Plateau uplift episode or La Sal Mountains volcanism.

  15. Enhancement of aged and denatured fingerprints using the cyanoacrylate fuming technique following dusting with amino acid-containing powders.

    PubMed

    Nixon, Carly; Almond, Matthew J; Baum, John V; Bond, John W

    2013-03-01

    We have carried out experiments to investigate the aging of latent fingerprints deposited on black PVC over a period of 4-15 weeks. A thumbprint was used in each case and before deposition of the print the donor rubbed their thumb around their nose to add sebaceous deposits. We have studied the effect of heat, light, and moisture and we find that moisture is the most significant factor in the degradation of the latent print. We have attempted to enhance these latent prints by dusting with valine powder or powders composed of valine mixed with gold or red fluorescent commercial fingerprint powders. To make a direct comparison between "treated" and "untreated" prints, the prints were cut in half with one-half being "treated" and one-half not. Our studies show the best results being obtained when powders of valine and red fluorescent powders are applied prior to cyanoacrylate fuming.

  16. New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana

    USGS Publications Warehouse

    Flowerdew, M.J.; Daly, J.S.; Riley, T.R.

    2007-01-01

    Five of six Rb-Sr muscovite mineral isochron ages from the Scotia Metamorphic Complex of the South Orkney Islands, West Antarctica, average 190 ± 4 Ma. The muscovite ages are interpreted to date foliation-formation and thus also accretion and subduction at the Gondwana margin. Coincident picrite and ferropicrite magmatism, indicative of melts from deep-seated depleted mantle, permits a causative link between accretion and the arrival of the Karoo – Ferrar – Chon Aike mantle plume in the Early Jurassic. Three biotite Rb-Sr mineral isochron ages are consistently younger and average 176 ± 5 Ma. The biotite ages may record post-metamorphic cooling or more likely retrogressive metamorphic effects during uplift.

  17. MSHA review of silicosis and dust control in mining

    SciTech Connect

    Thaxton, R.

    1996-12-31

    Silicosis has become a forgotten disease. Many miners, when told of the risks of silicosis, indicate that they have never heard of the disease. A 1992 National Institute for Occupational Safety and Health (NIOSH) ALERT, however, pointed out that drilling in rock is hazardous to miners due to exposure to excessive amounts of silica-containing dust. Recent Mine Safety and Health Administration (MSHA) and NIOSH surveys also indicate that silicosis continues to be a significant health risk faced by miners. A joint field study conducted by NIOSH and MSHA in the Johnstown, Pennsylvania area found 8 cases of silicosis among 150 surveyed surface coal miners. Additional x-ray surveillance studies found 6 cases of disease among 234 current and former surface coal miners in the Poteau, Oklahoma area and 3 cases among 66 surface coal miners in the northern West Virginia area. These studies cannot be used to determine quantitative risk, or prevalence of the disease. They do, however, indicate the unacceptable reality that coal miners continue to develop silicosis. Surface miners are not the only miners potentially exposed to levels of silica-containing dust that may lead to development of silicosis. NIOSH and MSHA have received reports of disease among underground coal miners. Several of these cases involve coal miners under age 50. The focus of this presentation is to highlight the specific initiatives undertaken by MSHA`s Coal Mine Safety and Health to address this health hazard.

  18. Thermochronology of economic mineral deposits: dating the stages of mineralization at Panasqueira, Portugal, by high-precision 40Ar/ 39Ar age spectrum techniques on muscovite

    USGS Publications Warehouse

    Snee, L.W.; Sutter, J.F.; Kelly, W.C.

    1988-01-01

    This study is an example of a new and powerful application of 40Ar/39Ar age spectrum dating of muscovite. It is now possible to establish time constraints necessary for solving some of the long-standing problems in economic geology. Beyond this, the unique geologic situation of Panasqueira has allowed us to quantify the thermal characteristics of muscovite. Published fluid inclusion data have been used to estimate a muscovite argon closure temperature of ~325??C during rapid cooling or short reheating and a temperature of ~270??C during slow cooling or extended reheating. Argon-loss patterns displayed by all dated muscovites resulted from reheating after original closure; the mechanism for this argon loss appears to have been argon transport by volume diffusion. Thus, 40Ar/39Ar age spectrum dating of muscovite can be used to evaluate thermal conditions controlling argon diffusion as well as age, duration, and number of episodes of mineralization. -from Authors

  19. Dust in the Quasar Wind (Artist Concept)

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Dusty grains -- including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies -- can be seen blowing in the winds of a quasar, or active black hole, in this artist's concept. The quasar is at the center of a distant galaxy.

    Astronomers using NASA's Spitzer Space Telescope found evidence that such quasar winds might have forged these dusty particles in the very early universe. The findings are another clue in an ongoing cosmic mystery: where did all the dust in our young universe come from?

    Dust is crucial for efficient star formation as it allows the giant clouds where stars are born to cool quickly and collapse into new stars. Once a star has formed, dust is also needed to make planets and living creatures. Dust has been seen as far back as when the universe was less than a tenth of its current age, but how did it get there? Most dust in our current epoch forms in the winds of evolved stars that did not exist when the universe was young.

    Theorists had predicted that winds from quasars growing in the centers of distant galaxies might be a source of this dust. While the environment close to a quasar is too hot for large molecules like dust grains to survive, dust has been found in the cooler, outer regions. Astronomers now have evidence that dust is created in these outer winds.

    Using Spitzer's infrared spectrograph instrument, scientists found a wealth of dust grains in a quasar called PG2112+059 located at the center of a galaxy 8 billion light-years away. The grains - including corundum (sapphires and rubies); forsterite (peridot); and periclase (naturally occurring in marble) - are not typically found in galaxies without quasars, suggesting they might have been freshly formed in the quasar's winds.

  20. Genetic and environmental correlations between age at menarche and bone mineral density at different skeletal sites.

    PubMed

    Guo, Y; Zhao, L-J; Shen, H; Guo, Y; Deng, H-W

    2005-12-01

    Low bone mineral density (BMD) is an important risk factor for osteoporotic fractures. Though previous studies have demonstrated that age at menarche (AAM) is phenotypically associated with BMD, the contributions of genetic and environmental factors to this association remain unknown. In this study, using variance decomposition analyses, we provided an accurate estimation of the genetic and environmental correlations between AAM and BMD in 2,667 Caucasian women from 512 pedigrees. After adjustment for significant covariates, we detected significant genetic correlations between AAM and BMD at the lumbar spine, femoral neck, and ultradistal radius (rho(G) = -0.1316, -0.1417, and -0.1137, respectively; all P < 0.01). However, all environmental correlations between AAM and BMD were nonsignificant (P > 0.05). We also generated a principal component factor for BMD (PC_BMD) and evaluated the relationship between this factor and AAM. The genetic and environmental correlations between PC_BMD and AAM (rho(P) = -0.0847, P < 0.001; rho(G) = -0.1737, P < 0.01; rho(E) = -0.0348, P > 0.05) were consistent with the results of BMD at the three skeletal sites and AAM. Our results confirmed the significant phenotypic association between BMD and AAM and for the first time suggested that this association is mainly attributable to shared genetic, rather than environmental, factors.

  1. Age-related transparent root dentin: mineral concentration, crystallite size, and mechanical properties.

    PubMed

    Kinney, J H; Nalla, R K; Pople, J A; Breunig, T M; Ritchie, R O

    2005-06-01

    Many fractures occur in teeth that have been altered, for example restored or endodontically repaired. It is therefore essential to evaluate the structure and mechanical properties of these altered dentins. One such altered form of dentin is transparent (sometimes called sclerotic) dentin, which forms gradually with aging. The present study focuses on differences in the structure and mechanical properties of normal versus transparent dentin. The mineral concentration, as measured by X-ray computed microtomography, was significantly higher in transparent dentin, the elevated concentration being consistent with the closure of the tubule lumens. Crystallite size, as measured by small angle X-ray scattering, was slightly smaller in transparent dentin, although the importance of this finding requires further study. The elastic properties were unchanged by transparency; however, transparent dentin, unlike normal dentin, exhibited almost no yielding before failure. In addition, the fracture toughness was lowered by roughly 20% while the fatigue lifetime was deleteriously affected at high stress levels. These results are discussed in terms of the altered microstructure of transparent dentin.

  2. Mass-specific optical absorption coefficients and imaginary part of the complex refractive indices of mineral dust components measured by a multi-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2015-01-01

    Mass-specific optical absorption coefficients (MACs) and the imaginary part (κ) of the refractive indices of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at the wavelengths of 1064, 532, 355 and 266 nm. The MAC values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. Values of κ were calculated from the measured and particle-loss-corrected data by using a Mie-theory-based retrieval algorithm. The determined values could be used for comparisons with calculated wavelength-dependent κ values typically deduced from bulk-phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk-phase measurements.

  3. Application of Markov chain Monte Carlo analysis to biomathematical modeling of respirable dust in US and UK coal miners

    PubMed Central

    Sweeney, Lisa M.; Parker, Ann; Haber, Lynne T.; Tran, C. Lang; Kuempel, Eileen D.

    2015-01-01

    A biomathematical model was previously developed to describe the long-term clearance and retention of particles in the lungs of coal miners. The model structure was evaluated and parameters were estimated in two data sets, one from the United States and one from the United Kingdom. The three-compartment model structure consists of deposition of inhaled particles in the alveolar region, competing processes of either clearance from the alveolar region or translocation to the lung interstitial region, and very slow, irreversible sequestration of interstitialized material in the lung-associated lymph nodes. Point estimates of model parameter values were estimated separately for the two data sets. In the current effort, Bayesian population analysis using Markov chain Monte Carlo simulation was used to recalibrate the model while improving assessments of parameter variability and uncertainty. When model parameters were calibrated simultaneously to the two data sets, agreement between the derived parameters for the two groups was very good, and the central tendency values were similar to those derived from the deterministic approach. These findings are relevant to the proposed update of the ICRP human respiratory tract model with revisions to the alveolar-interstitial region based on this long-term particle clearance and retention model. PMID:23454101

  4. A Sensitivity Study on the Effects of Particle Chemistry, Asphericity and Size on the Mass Extinction Efficiency of Mineral Dust in the Earth's Atmosphere: From the Near to Thermal IR

    NASA Technical Reports Server (NTRS)

    Hansell, R. A., Jr.; Reid, J. S.; Tsay, S. C.; Roush, T. L.; Kalashnikova, O. V.

    2011-01-01

    To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model particle size, while composition is defined by the refractive indices of minerals routinely observed in dust, including the widely used OPAC/Hess parameterization. Single-scattering properties of representative dust particle shapes are calculated using the T-matrix, Discrete Dipole Approximation and Lorenz-Mie light-scattering codes. For the parameterizations examined, MEE ranges from nearly zero to 1.2 square meters per gram, with the higher values associated with non-spheres composed of quartz and gypsum. At near-IR wavelengths, MEE for non-spheres generally exceeds those for spheres, while in the thermal IR, shape-induced changes in MEE strongly depend on volume median diameter (VMD) and wavelength, particularly for MEE evaluated at the mineral resonant frequencies. MEE spectral distributions appear to follow particle geometry and are evidence for shape dependency in the optical properties. It is also shown that non-spheres best reproduce the positions of prominent absorption peaks found in silicates. Generally, angular particles exhibit wider and more symmetric MEE spectral distribution patterns from 8-10 micrometers than those with smooth surfaces, likely due to their edge-effects. Lastly, MEE ratios allow for inferring dust optical properties across the visible-IR spectrum. We conclude the MEE of dust aerosol are significant for the parameter space investigated, and are a key component for remote sensing applications and the study of direct aerosol radiative effects.

  5. 30 CFR 57.9315 - Dust control.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Dust control. 57.9315 Section 57.9315 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND....9315 Dust control. Dust shall be controlled at muck piles, material transfer points, crushers, and...

  6. 30 CFR 57.9315 - Dust control.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Dust control. 57.9315 Section 57.9315 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND....9315 Dust control. Dust shall be controlled at muck piles, material transfer points, crushers, and...

  7. ‘This is the country of premature old men’ Ageing and Aged Miners in the South Wales Coalfield, c.1880–1947

    PubMed Central

    Curtis, Ben; Thompson, Steven

    2015-01-01

    Abstract This article considers the effects of work in the south Wales coal industry either side of the turn of the twentieth century and, specifically, the ways in which work aged workers prematurely. It examines the consequences of working practices for miners’ bodies, the expedients utilized by miners to try and cope with the effects of premature ageing, and the consequences for their living standards, experiences and status. It situates these phenomena in the contexts of industrial relations and welfare provision. In so doing, the article engages with historiographies of the life-cycle, the aged, and pensions provision in modern Britain. PMID:27134572

  8. K Ar ages of plutonism and mineralization at the Shizhuyuan W Sn Bi Mo deposit, Hunan Province, China

    NASA Astrophysics Data System (ADS)

    Yin, Jingwu; Kim, Sang Jung; Lee, Hyun Koo; Itay, Tetsumaru

    2002-01-01

    The Qianlishan granite complex, situated 16 km southeast of Chenzhou City, Hunan Province, China, hosts the Shizhuyuan W-Sn-Bi-Mo deposit. This complex, which intruded the Protozoic metasedimentary rocks and the Devonian clastic sedimentary and carbonate rocks, consists of mainly medium- to coarse-grained biotite granites and minor amounts of fine-grained biotite granite in addition to granite and quartz porphyry. K-Ar ages suggest three episodes of plutonism: the medium- to coarse-grained biotite granite (before 152 Ma), the fine-grained biotite granite (137 Ma), and the granite porphyry (129-131 Ma). Muscovite ages of the greisen are 145-148 Ma, suggesting that the W-Sn-Bi-Mo mineralization was related to the main, medium- to coarse-grained biotite granites. The K-Ar age of the hydrothermal vein mineralization is 92 Ma and is probably related to the porphyries.

  9. Metrologically-Calibrated 40Ar Concentrations and Ages of Mineral Standards Used in 40Ar/39Ar Geochronology

    NASA Astrophysics Data System (ADS)

    Morgan, L. E.; Davidheiser-Kroll, B.; Kuiper, K.; Wijbrans, J. R.; Mark, D. F.

    2015-12-01

    In geochronology, isotopic ages are determined from the ratio of parent and daughter nuclide concentrations in minerals. For dating of geological material using the K-Ar system, the simultaneous determination of 40Ar and 40K concentrations on the same aliquot is not possible. Therefore, a widely used variant, the 40Ar/39Ar technique, involves the production of 39Ar from 39K by neutron bombardment and the reliance on indirect natural calibrators of the neutron flux, referred to as "mineral standards." Many mineral standards still in use rely on decades-old determinations of 40Ar concentrations; resulting uncertainties, both systematic and analytical, impede the determination of higher accuracy ages using the K-Ar decay system. We present results for the 40Ar concentrations and ages of mineral standards determined based on a modern gas delivery system (Morgan et al. 2011), which delivers metrologically-traceable amounts of 40Ar and thus allows for the sensitivity calibration of noble gas mass spectrometers.

  10. Occupational dust exposure and chronic obstructive pulmonary disease. A systematic overview of the evidence.

    PubMed

    Oxman, A D; Muir, D C; Shannon, H S; Stock, S R; Hnizdo, E; Lange, H J

    1993-07-01

    The object of this study was to assess the relationship between occupational dust exposure and chronic obstructive pulmonary disease (COPD). Studies were identified using MEDLINE (January 1966 to July 1991), SCISEARCH, manual review of reference lists, and personal contact with more than 30 international experts. Studies of COPD, lung function, emphysema, chronic bronchitis, or mortality in workers exposed to nonorganic dust were retrieved. Studies were included if dust exposure was measured quantitatively, and a quantitative relationship between dust exposure and one of the outcomes of interest was calculated while controlling at least for smoking and age. Methodological rigor was assessed, and data regarding the study populations, prognostic factors, and outcomes were extracted independently by two reviewers. Thirteen reports derived from four cohorts of workers met our inclusion criteria. Three of the cohorts were of coal miners and one was of gold miners. All of the studies found a statistically significant association between loss of lung function and cumulative respirable dust exposure. It was estimated that 80 (95% CI, 34 to 137) of 1,000 nonsmoking coal miners with a cumulative respirable dust exposure of 122.5 gh/m3 (considered equivalent to 35 years of work with a mean respirable dust level of 2 mg/m3) could be expected to develop a clinically important (> 20%) loss of FEV1 attributable to dust. Among 1,000 smoking miners the comparable estimate was 66 (95% CI, 49 to 84). The risk of a clinically important loss of lung function attributable to dust among nonsmoking gold miners was estimated to be three times as large as for coal miners at less than one fifth of the cumulative respirable dust exposure (21.3 gh/m3), the maximal exposure observed among the cohort of gold miners. We conclude that occupational dust is an important cause of COPD, and the risk appears to be greater for gold miners than for coal miners. One possible explanation of the greater

  11. The Kenticha rare-element pegmatite, Ethiopia: internal differentiation, U-Pb age and Ta mineralization

    NASA Astrophysics Data System (ADS)

    Küster, Dirk; Romer, Rolf L.; Tolessa, Dandena; Zerihun, Desta; Bheemalingeswara, K.; Melcher, Frank; Oberthür, Thomas

    2009-10-01

    The Kenticha rare-element pegmatite, a globally important tantalite source in the Neoproterozoic Adola Belt of southern Ethiopia, is a highly fractionated, huge (2,000 m long and up to 100 m thick), subhorizontal, sheet-like body, discordantly emplaced in ultramafic host rock. It corresponds to the spodumene subtype of the rare-element pegmatite class and belongs to the lithium-cesium-tantalum petrogenetic family. The Kenticha pegmatite is asymmetrically zoned from bottom to top into granitic lower zone, spodumene-free intermediate zone, and spodumene-bearing upper zone. A monomineralic quartz unit is discontinuously developed within the upper zone. Whole-rock data indicate an internal geochemical differentiation of the pegmatite sheet proceeding from the lower zone (K/Rb ~36, K/Cs ~440, Al/Ga ~2,060, Nb/Ta ~2.6) to the upper zone (K/Rb ~19, K/Cs ~96, Al/Ga ~1,600, Nb/Ta ~0.7). The latter one is strongly enriched in Li2O (up to 3.21%), Rb (up to 4,570 ppm), Cs (up to 730 ppm), Ga (up to 71 ppm), and Ta (up to 554 ppm). Similar trends of increasing fractionation from lower zone to upper zone were obtained in muscovite (K/Rb 23-14, K/Cs 580-290, K/Tl 6,790-3,730, Fe/Mn 19-10, Nb/Ta 6.5-3.8) and columbite-tantalite (Mn/Mn + Fe 0.4-1, Ta/Ta + Nb 0.1-0.9). The bottom-to-top differentiation of the Kenticha pegmatite and the Ta mineralization in its upper part are principally attributed to upward in situ fractionation of a residual leucogranitic to pegmatitic melt, largely under closed system conditions. High MgO contents (up to 5.05%) in parts of the upper zone are the result of postmagmatic hydrothermal alteration and contamination by hanging wall serpentinite. U-Pb dating of Mn-tantalite from two zones of the Kenticha pegmatite gave ages of 530.2 ± 1.3 and 530.0 ± 2.3 Ma. Mn-tantalite from the Bupo pegmatite, situated 9 km north of Kenticha, gave an age of 529.2 ± 4.1 Ma, indicating coeval emplacement of the two pegmatites. The emplacement of the pegmatites is

  12. Age-related changes in osteometry, bone mineral density and osteophytosis of the lumbar vertebrae in Japanese macaques.

    PubMed

    Pomchote, Porrawee

    2015-01-01

    The age-related changes in lumbar vertebrae were studied in 77 young/full adult Japanese macaques (Macaca fuscata) (40 females, 37 males), in terms of their morphometry, density and osteophytosis, and the interrelationship between these three aspects. The most common age-related pattern of morphometric changes was an initial increase during young adulthood until reaching the peak and then a subsequent decrease with age. Most of the peaks were in the age group 15-20 and 10-15 years in females and males, respectively. In both sexes, the age-related decrease in the vertebral body depth (ventro-dorsal) was greater than in the height and width. The ventral height of the vertebral body relative to the dorsal height continuously decreased with age. The trabecular bone mineral density (BMD) continuously decreased after young adulthood. However, the magnitude of the decreased trabecular BMD with age was greater in females than in males, especially in the older age groups. Osteophytosis clearly increased with age in both sexes, but males showed an earlier appearance of osteophytes and females tended to have more severe osteophytes from 15 years old upwards. A correlation between the osteometry, density, and osteophytosis severity appeared in all vertebrae, but not all of these reached statistical significance after controlling for the influence of age. Although Japanese macaques showed the higher prevalence and rapid increase of osteophytosis, a similar age change profile was observed in the lumbar vertebrae of Japanese macaques and humans.

  13. U-Pb geochronology of the Lagoa Real uranium district, Brazil: Implications for the age of the uranium mineralization

    NASA Astrophysics Data System (ADS)

    Lobato, Lydia Maria; Pimentel, Márcio Martins; Cruz, Simone C. P.; Machado, Nuno; Noce, Carlos Maurício; Alkmim, Fernando Flecha

    2015-03-01

    The Lagoa Real uranium district in Bahia, northeastern Brazil, is the most important uranium province in the country and presently produces this metal in an open-pit mine operated by Indústrias Nucleares do Brasil. Uranium-rich zones are associated with plagioclase (dominantly albite ± oligoclase) -rich rocks, albitites and metasomatized granitic-gneisses, distributed along NNW/SSE striking shear zones. We have used the ID-TIMS U-Pb method to date zircon and titanite grains from the São Timóteo granitoid, and albite-rich rocks from the Lagoa Real district in order to assess the age of granite emplacement, deformation/metamorphism and uranium mineralization. The isotopic data support the following sequence of events (i) 1746 ± 5 Ma - emplacement of the São Timóteo granitoid (U-Pb zircon age) in an extensional setting, coeval with the beginning of the sedimentation of the Espinhaço Supergroup; (ii) 956 ± 59 Ma hydrothermal alteration of the São Timóteo granitoid and emplacement of the uranium mineralization (U-Pb titanite age on an albite-rich sample); (iii) 480 Ma metamorphism, remobilization and Pb loss (U-Pb titanite age for the gneiss sample), during the nucleation of shear zones related to the collision between the São Francisco-Congo and Amazonia paleoplates. The 956 ± 59-Ma mineralization age is apparently associated with the evolution of the Macaúbas-Santo Onofre rift. This age bracket may bear an important exploration implication, and should be included in the diverse age scenario of uranium deposits worldwide.

  14. Assessment of MODIS-Derived Visible and Near-IR Aerosol Optical Properties and their Spatial Variability in the Presence of Mineral Dust

    NASA Technical Reports Server (NTRS)

    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.

  15. Stable isotope ratio measurements of Cu and Zn in mineral dust (bulk and size fractions) from the Taklimakan Desert and the Sahel and in aerosols from the eastern tropical North Atlantic Ocean.

    PubMed

    Dong, Shuofei; Weiss, Dominik J; Strekopytov, Stanislav; Kreissig, Katharina; Sun, Youbin; Baker, Alex R; Formenti, Paola

    2013-09-30

    Accurate characterization of the stable isotope composition of Cu and Zn in major global mineral dust sources and in aerosols is central to the application of these isotope systems to the studies of global geochemical processes and cycles. We test here for the first time Cu and Zn isotope ratios within a well-defined source-receptor setting on the continent-ocean interface and determine the isotope composition of (i) bulk surface soil dust samples from the Sahel region, (ii) individual size fractions of surface dust samples from the Taklimakan Desert, and (iii) aerosols collected in the equatorial eastern North Atlantic region. This is achieved reducing the blank contribution during the ion exchange step using small resin and acid volumes and using a second ion exchange passage to purify the Cu fraction. We find no significant correlation between size fractions and isotope ratios in the two samples analyzed from the Taklimakan Desert. Mass balance calculations suggest that isotope ratios of bulk samples are within the analytical precision of the <4 μm size fraction and can be used to characterize atmospheric long range transport of Cu and Zn in mineral dust from the Taklimakan Desert. The <1 µm size fractions of two aerosol samples collected over the equatorial eastern North Atlantic region have Cu and Zn isotope ratios that are different to Sahel surface soil dust suggesting important non-crustal sources, in line with calculated enrichment factors, and possibly of anthropogenic origin. Using previously reported δ(66)Zn values for anthropogenic emission from Europe, preliminary calculations suggest that up to 55% of Zn arriving at the sampling points in the equatorial eastern North Atlantic region could be of anthropogenic origin.

  16. Beryllium geochemistry in soils: Evaluation of 10Be/9Be ratios in authigenic minerals as a basis for age models

    USGS Publications Warehouse

    Barg, E.; Lal, D.; Pavich, M.J.; Caffee, M.W.; Southon, J.R.

    1997-01-01

    Soils contain a diverse and complex set of chemicals and minerals. Being an 'open system', both in the chemical and nuclear sense, soils have defied quantitative nuclear dating. However, based on the published studies of the cosmogenic atmospheric 10Be in soils, its relatively long half-life (1.5 Ma), and the fact that 10Be gets quickly incorporated in most soil minerals, this radionuclide appears to be potentially the most useful for soil dating. We therefore studied the natural variations in the specific activities of 10Be with respect to the isotope 9Be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals, following an earlier suggestion [Lal et al., 1991. Development of cosmogenic nuclear methods for the study of soil erosion and formation rates. Current Sci. 61, 636-639.]. We find that the 10Be/9Be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10Be concentrations. Also, the highest 10Be/9Be ratios in authigenic minerals are observed at the soil-rock interface as predicted by the model. We present model 10Be/9Be ages of the B-horizon and the corresponding soil formation rates for several soil profiles. The present study demonstrates that the 10Be/9Be ratios in the authigenic phases, e.g. clay and Fe-hydroxides, can indeed be used for obtaining useful model ages for soils younger than 10-15 Ma. However, the present work has to be pushed considerably further, to take into account more realistic age models in which, for instance, downward transport of 10Be and clays, and in-situ dissolution of clay minerals at depths, altering the 10Be/9Be ratios of the acidic solutions, are included. We show that in the case of younger soils (< 1 Ma) studied here, their 10Be inventories and 10Be/9Be ratios have been significantly disturbed possibly by mixing with transported

  17. Mineralization of the connective tissue: a complex molecular process leading to age-related loss of function.

    PubMed

    Shindyapina, Anastasia V; Mkrtchyan, Garik V; Gneteeva, Tatiana; Buiucli, Sveatoslav; Tancowny, B; Kulka, M; Aliper, Alexander; Zhavoronkov, Alexander

    2014-04-01

    Age-related metastatic mineralization of soft tissues has been considered a passive and spontaneous process. Recent data have demonstrated that calcium salt deposition in soft tissues could be a highly regulated process. Although calcification occurs in any tissue type, vascular calcification has been of particular interest due to association with atherosclerosis, chronic kidney disease (CKD), and osteoporosis. Different mechanisms underlying calcium apatite accumulation are explored with these age-related disorders. In the case of atherosclerotic plaques, oxy-lipids trigger release of the pro-inflammatory cytokines and inflammation that activate calcification processes in aorta intimae. In CKD patients, renal failure alters the balance between calcium and phosphate levels usually regulated by fibroblast growth factor-23 (FGF23), Klotho, and vitamin D, and vascular smooth muscle cells (VSMCs) begin to explore an osteoblastosteoblast-like phenotype. Calcification could affect extracellular matrix along with VSMCs. Collagen is a major component of extracellular matrix and its modifications accumulate with age. The formation of cross-links between collagen fibers is regulated by the action of lysine hydroxylases and lysyl oxidase and could occur spontaneously. Oxidation-induced advanced glycation end products (AGEs) are a major type of spontaneous cross-links that accelerate with age and may result in tissue stiffness, problems with recycling, and potential accumulation of calcium apatite. Applying strategies for clearing the AGEs proposed by de Grey may be more difficult in the highly mineralized extracellular matrix. We performed bioinformatic analysis of the molecular pathways underlying calcification in atherosclerotic and CKD patients, signaling pathways of collagen cross-links formation, and bone mineralization, and we propose new potential targets and review drugs for calcification treatment. PMID:23902273

  18. Changes in the mineral density distribution in human bone with age: image analys