Potentially toxic metal contamination of urban soils and roadside dust in Shanghai, China

Energy Technology Data Exchange (ETDEWEB)

Shi Guitao [Key Laboratory of Geographic Information Science of Ministry of Education, East China Normal University, Shanghai 200062 (China); Chen Zhenlou [Key Laboratory of Geographic Information Science of Ministry of Education, East China Normal University, Shanghai 200062 (China)], E-mail: gt_shi@163.com; Xu Shiyuan [Key Laboratory of Geographic Information Science of Ministry of Education, East China Normal University, Shanghai 200062 (China); Zhang Ju [School of Environment and Planning, Liaocheng University, Liaocheng 252059 (China); Wang Li; Bi Chunjuan [Key Laboratory of Geographic Information Science of Ministry of Education, East China Normal University, Shanghai 200062 (China); Teng Jiyan [Shanghai Chongming Dongtan National Nature Reserve, Shanghai 202183 (China)

2008-11-15

A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition. - Human activities have led to high accumulation of potentially toxic metals in urban soils and roadside dust of Shanghai.

Simple Methods for Production of Nanoscale Metal Oxide Films from Household Sources

Science.gov (United States)

Campbell, Dean J.; Baliss, Michelle S.; Hinman, Jordan J.; Ziegenhorn, John W.; Andrews, Mark J.; Stevenson, Keith J.

2013-01-01

Production of thin metal oxide films was recently explored as part of an outreach program with a goal of producing nanoscale structures with household items. Household items coated with various metals or titanium compounds can be heated to produce colorful films with nanoscale thicknesses. As part of a materials chemistry laboratory experiment…

Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?

Energy Technology Data Exchange (ETDEWEB)

Hopkins, Philip F. [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Conroy, Charlie, E-mail: phopkins@caltech.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-02-01

Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances of these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.

Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?

International Nuclear Information System (INIS)

Hopkins, Philip F.; Conroy, Charlie

2017-01-01

Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances of these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.

Trace Metals and Mineral Composition of Harmattan Dust Haze in ...

African Journals Online (AJOL)

ADOWIE PERE

2018-01-29

Jan 29, 2018 ... ABSTRACT: Trace metals and mineralogical composition of harmattan dust haze was carried out on samples collected at Ilorin (80 32'N, ... Sahara desert which transports the dust by wind. Junge (1979) reported that on the .... Schwela et al 2002, it was observed that road transport emission sources ...

Phytoremediation Reduces Dust Emissions from Metal(loid)-Contaminated Mine Tailings.

Science.gov (United States)

Gil-Loaiza, Juliana; Field, Jason P; White, Scott A; Csavina, Janae; Felix, Omar; Betterton, Eric A; Sáez, A Eduardo; Maier, Raina M

2018-04-27

Environmental and health risk concerns relating to airborne particles from mining operations have focused primarily on smelting activities. However, there are only three active copper smelters and less than a dozen smelters for other metals compared to an estimated 500000 abandoned and unreclaimed hard rock mine tailings in the US that have the potential to generate dust. The problem can also extend to modern tailings impoundments, which may take decades to build and remain barren for the duration before subsequent reclamation. We examined the impact of vegetation cover and irrigation on dust emissions and metal(loid) transport from mine tailings during a phytoremediation field trial at the Iron King Mine and Humboldt Smelter Superfund (IKMHSS) site. Measurements of horizontal dust flux following phytoremediation reveals that vegetated plots with 16% and 32% canopy cover enabled an average dust deposition of 371.7 and 606.1 g m -2 y -1 , respectively, in comparison to the control treatment which emitted dust at an average rate of 2323 g m -2 y -1 . Horizontal dust flux and dust emissions from the vegetated field plots are comparable to emission rates in undisturbed grasslands. Further, phytoremediation was effective at reducing the concentration of fine particulates, including PM 1 , PM 2.5 , and PM 4 , which represent the airborne particulates with the greatest health risks and the greatest potential for long-distance transport. This study demonstrates that phytoremediation can substantially decrease dust emissions as well as the transport of windblown contaminants from mine tailings.

Heavy metal levels and solid phase speciation in street dusts of Delhi, India

International Nuclear Information System (INIS)

Banerjee, Anju D.K.

2003-01-01

Although the street dusts of Delhi contain considerably high levels of Cr, Ni, Cu, Cd, Zn and Pb, solid phase speciation results indicate comparatively limited environmental mobility and bioavailability of Ni and Cr. - Street dust samples were collected from three different localities (industrial, heavy traffic and rural) situated in the greater Delhi area of India. The samples analyzed for Cd, Zn, Pb, Ni, Cu, and Cr indicated remarkably high levels of Cr, Ni, and Cu in the industrial area, whilst Pb and Cd did not show any discernible variations between the three localities. A multivariate statistical approach (Principal Component Analysis) was used to define the possible origin of metals in dusts. The street dusts were sequentially extracted so that the solid pools of Cd, Zn, Pb, Ni, Cu, Cr could be partitioned into five operationally defined fractions viz. exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. Metal recoveries in sequential extractions were ±10% of the independently measured total metal concentrations. Cd was the only metal present appreciably (27.16%) in the exchangeable fraction and Cu was the only metal predominantly associated (44.26%) with organic fraction. Zn (45.64%) and Pb (28.26%) were present mainly in the Fe-Mn oxide fraction and the residual fraction was the most dominant solid phase pool of Cr (88.12%) and Ni (70.94%). Assuming that the mobility and bioavailability are related to the solubility of geochemical forms of the metals and decrease in order of extraction, the apparent mobility and potential metal bioavailability for these highly contaminated street dust samples is: Cd>Zn congruent with Pb>Ni>Cu>Cr

[Investigation of heavy metal and polycyclic aromatic hydrocarbons contamination in street dusts in urban Beijing].

Science.gov (United States)

Xiang, Li; Li, Ying-Xia; Shi, Jiang-Hong; Liu, Jing-Ling

2010-01-01

This paper investigated the contamination levels of heavy metal and polycyclic aromatic hydrocarbons (PAHs) in street dusts in different functional areas in urban Beijing. Results show that the mean concentrations of Cd, Hg, Cr, Cu, Ni, Pb and Zn in street dusts in Beijing are 710 ng/g, 307 ng/g, 85.0 microg/g, 78.3 microg/g, 41.1 microg/g, 69.6 microg/g and 248.5 microg/g, respectively, which are significantly lower than those in most cities around the world and Shenyang, Shanghai in China. The mean concentration of Sigma 16PAHs in street dusts in Beijing is 0.398 microg/g, which is also lower than those of Handan, Tianjin and Shanghai. Non-parametric Friedman test demonstrates significant differences of heavy metal contents on street dusts from different functional zones. Street dusts in residential area and parks have lower heavy metal and PAHs concentrations than the street dusts from areas of high traffic density. The concentrations of heavy metals follow the order Zn > Cr > Cu > Pb > Ni > Cd > Hg, which is consistent with the situation in other cities around the world. The geoaccumulation index analysis shows that street dust in urban Beijing is moderately polluted by Cd, Zn and Cu, little polluted by Cr and Pb and practically unpolluted by Ni. The contamination levels of Sigma 16PAHs on street dusts vary greatly in different functional zones with parks little polluted, residential areas moderately to strongly polluted and traffic related areas strongly polluted to extremely polluted. Mass loading of heavy metals and PAHs is largely associated with street dusts of size range < 300 microm. Therefore, the urban sweeping vehicles should update the dust sweeping devices to remove not only the fine particle but also the coarser particles.

Application of synchrotron microprobe methods to solid-phase speciation of metals and metalloids in house dust.

Science.gov (United States)

Walker, S R; Jamieson, H E; Rasmussen, P E

2011-10-01

Determination of the source and form of metals in house dust is important to those working to understand human and particularly childhood exposure to metals in residential environments. We report the development of a synchrotron microprobe technique for characterization of multiple metal hosts in house dust. We have applied X-ray fluorescence for chemical characterization and X-ray diffraction for crystal structure identification using microfocused synchrotron X-rays at a less than 10 μm spot size. The technique has been evaluated by application to archived house dust samples containing elevated concentrations of Pb, Zn, and Ba in bedroom dust, and Pb and As in living room dust. The technique was also applied to a sample of soil from the corresponding garden to identify linkages between indoor and outdoor sources of metals. Paint pigments including white lead (hydrocerussite) and lithopone (wurtzite and barite) are the primary source of Pb, Zn, and Ba in bedroom dust, probably related to renovation activity in the home at the time of sampling. The much lower Pb content in the living room dust shows a relationship to the exterior soil and no specific evidence of Pb and Zn from the bedroom paint pigments. The technique was also successful at confirming the presence of chromated copper arsenate treated wood as a source of As in the living room dust. The results of the study have confirmed the utility of this approach in identifying specific metal forms within the dust.

Characterisation of metal combustion with DUST code

Energy Technology Data Exchange (ETDEWEB)

García-Cascales, José R., E-mail: jr.garcia@upct.es [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Velasco, F.J.S. [Centro Universitario de la Defensa de San Javier, MDE-UPCT, C/Coronel Lopez Peña s/n, 30730 Murcia (Spain); Otón-Martínez, Ramón A.; Espín-Tolosa, S. [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Bentaib, Ahmed; Meynet, Nicolas; Bleyer, Alexandre [Institut de Radioprotection et Sûreté Nucléaire, BP 17, 92260 Fontenay-aux-Roses (France)

2015-10-15

Highlights: • This paper is part of the work carried out by researchers of the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security of France. • We have developed a code for the study of mobilisation and combustion that we have called DUST by using CAST3M, a multipurpose software for studying many different problems of Mechanical Engineering. • In this paper, we present the model implemented in the code to characterise metal combustion which describes the combustion model, the kinetic reaction rates adopted and includes a first comparison between experimental data and calculated ones. • The results are quite promising although suggest that improvement must be made on the kinetic of the reaction taking place. - Abstract: The code DUST is a CFD code developed by the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security, France (IRSN) with the objective to assess the dust explosion hazard in the vacuum vessel of ITER. Thus, DUST code permits the analysis of dust spatial distribution, remobilisation and entrainment, explosion, and combustion. Some assumptions such as particle incompressibility and negligible effect of pressure on the solid phase make the model quite appealing from the mathematical point of view, as the systems of equations that characterise the behaviour of the solid and gaseous phases are decoupled. The objective of this work is to present the model implemented in the code to characterise metal combustion. In order to evaluate its ability analysing reactive mixtures of multicomponent gases and multicomponent solids, two combustion problems are studied, namely H{sub 2}/N{sub 2}/O{sub 2}/C and H{sub 2}/N{sub 2}/O{sub 2}/W mixtures. The system of equations considered and finite volume approach are briefly presented. The closure relationships used are commented and special attention is paid to the reaction rate correlations used in the model. The numerical

Geochemical investigation of potentially harmful elements in household dust from a mercury-contaminated site, the town of Idrija (Slovenia).

Science.gov (United States)

Bavec, Špela; Gosar, Mateja; Miler, Miloš; Biester, Harald

2017-06-01

A comprehensive geochemical investigation of potentially harmful elements (PHEs) in household dust from the town of Idrija (Slovenia), once a world-famous Hg mining town that is now seriously polluted, was performed for the first time. After aqua regia digestion, the content of mercury (Hg), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb) and zinc (Zn) was measured. PHE-bearing particles were recognised and observed by scanning electron microscopy and energy-dispersive spectrometry before and after exposure to simulated stomach acid (SSA). Mercury binding forms were identified by Hg thermal desorption technique and gastric bioaccessible Hg was estimated after SSA extraction by ICP-MS. With regard to rural and urban background values for Slovenia, high Hg content (6-120 mg/kg) and slightly elevated As content (1-13 mg/kg) were found. Mercury pollution is a result of past mining and ore processing activities. Arsenic content is potentially associated with As enrichment in local soils. Four Hg binding forms were identified: all samples contained Hg bound to the dust matrix, 14 samples contained cinnabar, two samples contained metallic Hg (Hg 0 ), and one sample assumingly contained mercury oxide. After exposure to SSA, Hg-bearing phases showed no signs of dissolution, while other PHE-bearing phases were significantly morphologically and/or chemically altered. Estimated gastric Hg bioaccessibility was low (<0.006-0.09 %), which is in accordance with identified Hg binding forms and high organic carbon content (15.9-31.5 %) in the dust samples.

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

NARCIS (Netherlands)

Amato, F.; Schaap, M.; Denier van der Gon, H.A.C.; Pandolfi, M.; Alastuey, A.; Keuken, M.; Querol, X.

2013-01-01

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

Multivariate statistical analysis of heavy metals in street dust of Baoji, NW China

International Nuclear Information System (INIS)

Lu Xinwei; Wang Lijun; Li, Loretta Y.; Lei Kai; Huang Li; Kang Dan

2010-01-01

The concentrations of Pb, Cu, Zn, Mn, Ni, Co and Cr in street dust samples from Baoji in north-west China were measured by wavelength dispersive X-ray fluorescence spectrometry, while As and Hg in street dust samples were determined by atomic fluorescence spectrometry. Principal component analysis and cluster analysis, coupled with correlation coefficient analysis, were used to analyze the data and to identify possible sources of these heavy metals. The results indicate that street dust in Baoji has elevated heavy metal concentrations, especially Hg, Pb, Zn and Cu, which are 16-77, 7-92, 6-26 and 4-12 times the background levels in Shaanxi soil, respectively. The mean heavy metal concentrations in street dust divided by the corresponding background values of Shaanxi soil decrease in the order of Hg > Pb > Zn > Cu > Cr > As > Ni > Co > Mn > V. Three main sources of these heavy metals were identified. As, V, Pb and Co originated from nature and traffic. Cu, Zn, Hg and Mn, especially the former two, mainly derive from industry sources, as well as traffic. Cr and Ni mainly originate from soil.

Response of magnetic properties to heavy metal pollution in dust from three industrial cities in China

International Nuclear Information System (INIS)

Zhu, Zongmin; Li, Zhonggen; Bi, Xiangyang; Han, Zhixuan; Yu, Genhua

2013-01-01

Highlights: ► Elevated magnetic particles and heavy metals coexist in dust. ► Morphology and mineralogy of magnetic particles were studied by SEM-EDX and XRD. ► Magnetic minerals in the dust consist of magnetite, hematite, and metallic iron. ► Impact of metallic iron particles and multi-sources of metal pollutants was notable. -- Abstract: Magnetic method is a reliable and powerful technique for identification of the relative contribution of industrial pollutants. However, it has not been fully applied in urban area impacted by non-ferrous metal (NFM) smelting/processing activities. The aim of this study is to explore the applicability of magnetic methods for detecting heavy metal contamination in dust from three NFM smelting/processing industrial cities (Ezhou, Zhuzhou, and Hezhang) in China. The enhancements of magnetic susceptibility (MS) and saturation isothermal remanent magnetization (SIRM) together with heavy metals were significant in the studied areas in comparison with the background values. Scanning electron microscope (SEM) analysis revealed that magnetic particles in dust from Ezhou were dominated by spherules, while those from Zhuzhou and Hezhang were mainly consisted of irregular-shaped particles. κ–T curves and X-ray diffraction (XRD) analyses indicated that the magnetic particles from Ezhou were dominated by magnetite and metallic iron, whereas those from Zhuzhou and Hezhang were consisted of magnetite and hematite. Our study indicates that magnetic properties of the dust are sensitive to the NFM smelting/processing related heavy metal pollutants. However, the relationship between magnetic parameters and heavy metals was influenced by the presence of metallic iron particles and multi-sources of metal pollutants

Grain Size Distribution and Health Risk Assessment of Metals in Outdoor Dust in Chengdu, Southwestern China.

Science.gov (United States)

Chen, Mengqin; Pi, Lu; Luo, Yan; Geng, Meng; Hu, Wenli; Li, Zhi; Su, Shijun; Gan, Zhiwei; Ding, Sanglan

2016-04-01

A total of 27 outdoor dust samples from roads, parks, and high spots were collected and analyzed to investigate the contamination of 11 metals (Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Cd, Sb, and Pb) in Chengdu, China. The results showed that the samples from the high spots exhibited the highest heavy metal level compared with those from the roads and the parks, except for Ni, Cu, and Pb. The dust was classified into five grain size fractions. The mean loads of each grain size fraction of 11 determined metals displayed similar distribution, and the contribution of median size (63-125, 125-250, 250-500 μm) fractions accounted for more than 70% of overall heavy metal loads. The health risk posed by the determined metals to human via dust ingestion, dermal contact, and inhalation was investigated. Oral and respiratory bioaccessible parts of the metals in dust were extracted using simulated stomach solution and composite lung serum. The mean bioaccessibilities of 11 investigated metals in the gastric solution were much higher than those in the composite lung serum, especially Zn, Cd, and Pb. Ingestion was the most important exposure pathway with percentage greater than 70% for both children and adults. Risk evaluation results illustrated that children in Chengdu might suffer noncarcinogenic risk when exposed to outdoor dust. Given that the cancer risk values of Pb and Cr larger than 1 × 10(-4), potential carcinogenic risk might occur for Chengdu residents through outdoor dust intake.

Elastic–plastic adhesive impacts of tungsten dust with metal surfaces in plasma environments

Energy Technology Data Exchange (ETDEWEB)

Ratynskaia, S., E-mail: svetlana.ratynskaia@ee.kth.se [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Tolias, P. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Shalpegin, A. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-lès-Nancy (France); Vignitchouk, L. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); De Angeli, M. [Istituto di Fisica del Plasma – Consiglio Nazionale delle Ricerche, Milan (Italy); Bykov, I. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Bystrov, K.; Bardin, S. [FOM Institute DIFFER, Dutch Institute For Fundamental Energy Research, Edisonbaan 14, 3439MN Nieuwegein (Netherlands); Brochard, F. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-lès-Nancy (France); Ripamonti, D. [Istituto per l’Energetica e le Interfasi – Consiglio Nazionale delle Ricerche, Milan (Italy); Harder, N. den; De Temmerman, G. [FOM Institute DIFFER, Dutch Institute For Fundamental Energy Research, Edisonbaan 14, 3439MN Nieuwegein (Netherlands)

2015-08-15

Dust-surface collisions impose size selectivity on the ability of dust grains to migrate in scrape-off layer and divertor plasmas and to adhere to plasma-facing components. Here, we report first experimental evidence of dust impact phenomena in plasma environments concerning low-speed collisions of tungsten dust with tungsten surfaces: re-bouncing, adhesion, sliding and rolling. The results comply with the predictions of the model of elastic-perfectly plastic adhesive spheres employed in the dust dynamics code MIGRAINe for sub- to several meters per second impacts of micrometer-range metal dust.

Carbon formation and metal dusting in advanced coal gasification processes

Energy Technology Data Exchange (ETDEWEB)

DeVan, J.H.; Tortorelli, P.F.; Judkins, R.R.; Wright, I.G.

1997-02-01

The product gases generated by coal gasification systems contain high concentrations of CO and, characteristically, have relatively high carbon activities. Accordingly, carbon deposition and metal dusting can potentially degrade the operation of such gasifier systems. Therefore, the product gas compositions of eight representative gasifier systems were examined with respect to the carbon activity of the gases at temperatures ranging from 480 to 1,090 C. Phase stability calculations indicated that Fe{sub 3}C is stable only under very limited thermodynamic conditions and with certain kinetic assumptions and that FeO and Fe{sub 0.877}S tend to form instead of the carbide. As formation of Fe{sub 3}C is a necessary step in the metal dusting of steels, there are numerous gasifier environments where this type of carbon-related degradation will not occur, particularly under conditions associated with higher oxygen and sulfur activities. These calculations also indicated that the removal of H{sub 2}S by a hot-gas cleanup system may have less effect on the formation of Fe{sub 3}C in air-blown gasifier environments, where the iron oxide phase can exist and is unaffected by the removal of sulfur, than in oxygen-blown systems, where iron sulfide provides the only potential barrier to Fe{sub 3}C formation. Use of carbon- and/or low-alloy steels dictates that the process gas composition be such that Fe{sub 3}C cannot form if the potential for metal dusting is to be eliminated. Alternatively, process modifications could include the reintroduction of hydrogen sulfide, cooling the gas to perhaps as low as 400 C and/or steam injection. If higher-alloy steels are used, a hydrogen sulfide-free gas may be processed without concern about carbon deposition and metal dusting.

Indoor metallic pollution and children exposure in a mining city.

Science.gov (United States)

Barbieri, Enio; Fontúrbel, Francisco E; Herbas, Cristian; Barbieri, Flavia L; Gardon, Jacques

2014-07-15

Mining industries are known for causing strong environmental contamination. In most developing countries, the management of mining wastes is not adequate, usually contaminating soil, water and air. This situation is a source of concern for human settlements located near mining centers, especially for vulnerable populations such as children. The aim of this study was to assess the correlations of the metallic concentrations between household dust and children hair, comparing these associations in two different contamination contexts: a mining district and a suburban non-mining area. We collected 113 hair samples from children between 7 and 12 years of age in elementary schools in the mining city of Oruro, Bolivia. We collected 97 indoor dust samples from their households, as well as information about the children's behavior. Analyses of hair and dust samples were conducted to measure As, Cd, Pb, Sb, Sn, Cu and Zn contents. In the mining district, there were significant correlations between non-essential metallic elements (As, Cd, Pb, Sb and Sn) in dust and hair, but not for essential elements (Cu and Zn), which remained after adjusting for children habits. Children who played with dirt had higher dust-hair correlations for Pb, Sb, and Cu (P=0.006; 0.022 and 0.001 respectively) and children who put hands or toys in their mouths had higher dust-hair correlations of Cd (P=0.011). On the contrary, in the suburban area, no significant correlations were found between metallic elements in dust and children hair and neither children behavior nor gender modified this lack of associations. Our results suggest that, in a context of high metallic contamination, indoor dust becomes an important exposure pathway for children, modulated by their playing behavior. Copyright © 2014 Elsevier B.V. All rights reserved.

The spatial characteristics and pollution levels of metals in urban street dust of Beijing, China

International Nuclear Information System (INIS)

Tang, Rongli; Ma, Keming; Zhang, Yuxin; Mao, Qizheng

2013-01-01

Highlights: ·We explored the pollution characters of metals in street dust of Beijing. ·Area-source pollution and point-source pollution exist simultaneously. ·We identified the spatial autocorrelation intensities and ranges of metals. ·Metal pollution anomalies were identified by cluster and outlier analyses. ·Urban activities strongly influence the distributions of metals. - Abstract: The components and concentrations of metals in street dust are indictors of environmental pollution. To explore the pollution levels of Cd, Cr, Cu, Mn, Ni and Pb in street dust and their spatial distribution characteristics, 220 dust samples were collected in a grid pattern from urban street surfaces in Beijing. Multivariate statistics and spatial analyses were adopted to investigate the associations between metals and to identify their pollution patterns. In comparison with the soil background values, elevated metal concentrations were found, except those for Mn and Ni. The results of the geo-accumulation index (I geo ) and the potential ecological risk index (Er i ) of the metals revealed the following orders: Cd > Cu > Cr > Pb > Ni > Mn and Cd > Cu > Pb > Cr > Ni. Levels of I geo ranging from 0 to 5 were found and about 80% of the samples were below the moderately polluted level. The Er i values of single elements were within the low ecological risk level in most sampling sites. Most of the metals in the street dust of Beijing were statistically significantly correlated. It is hard to clearly identify the sources of each metal in the street dust since local environments are very complex. Cadmium, Cu, Cr, Mn and Pb showed medium spatial autocorrelations within the sampling region. Similar spatial distribution patterns were observed for Cu, Cr and Pb, and these metals had relatively high spatial variabilities and were enriched in the center of the city with several peaks scattered in the suburbs. Metal pollution anomalies were identified by using cluster and outlier analyses

Middle East Desert Dust Exposure: Health Risks from Metals and Microbial Pathogens

Science.gov (United States)

Lyles, M. B.

2014-12-01

In the Middle East, dust and sand storms are a persistent problem and can deliver significant amounts of micro-particulates via inhalation into the mouth, nasal pharynx, & lungs due to the fine size and abundance of these micro-particulates. The chronic and acute health risks of this dust inhalation have not been well studied nor has the dust been effectively characterized as to its chemical composition, mineral content, or microbial flora. Scientific experiments were designed to study the Kuwaiti and Iraqi dust as to its physical, chemical, and biological characteristics and for its potential to cause adverse health effects. First, dust samples from different locations were collected and processed and exposure data collected. Initial chemical and physical characterization of each sample including particle size distribution and inorganic analysis was conducted, followed by characterization of biologic flora of the dust, including bacteria, fungi and viruses. Data indicates that the mineralized dust is composed of calcium carbonate over a matrix of metallic silicate nanocrystals containing a variety of trace and heavy metals constituting ~3 % of the PM10 particles by weight, of which ~1% is bioaccessible aluminum and reactive iron, each. The particles also consist of ~1% bioavailable aluminum and reactive iron each. Microbial analysis reveals a significant biodiversity of bacterial, fungi, and viruses of which ~30% 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 PM 10 along with environmental & physiological conditions present constitute an excessive exposure to micro-particulates including PM 2.5 and the potential for adverse health effects. Reported data on cell culture and animal studies have indicated a high level of toxicity to these dust

Composition of Trace Metals in Dust Samples Collected from Selected High Schools in Pretoria, South Africa

Directory of Open Access Journals (Sweden)

J. O. Olowoyo

2016-01-01

Full Text Available Potential health risks associated with trace metal pollution have necessitated the importance of monitoring their levels in the environment. The present study investigated the concentrations and compositions of trace metals in dust samples collected from classrooms and playing ground from the selected high schools In Pretoria. Schools were selected from Pretoria based on factors such as proximity to high traffic ways, industrial areas, and residential areas. Thirty-two dust samples were collected from inside and outside the classrooms, where learners often stay during recess period. The dust samples were analysed for trace metal concentrations using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS. The composition of the elements showed that the concentrations of Zn were more than all other elements except from one of the schools. There were significant differences in the concentrations of trace metals from the schools (p<0.05. Regular cleaning, proximity to busy road, and well maintained gardens seem to have positive effects on the concentrations of trace metals recorded from the classrooms dust. The result further revealed a positive correlation for elements such as Pb, Cu, Zn, Mn, and Sb, indicating that the dust might have a common source.

Mineral phases and metals in baghouse dust from secondary aluminum production

Science.gov (United States)

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...

Metals and dust in the neutral ISM: the Galaxy, Magellanic Clouds, and damped Lyman-α absorbers

Science.gov (United States)

De Cia, Annalisa

2018-05-01

Context. The presence of dust in the neutral interstellar medium (ISM) dramatically changes the metal abundances that we measure. Understanding the metal content in the neutral ISM, and a direct comparison between different environments, has been hampered to date because of the degeneracy to the observed ISM abundances caused by the effects of metallicity, the presence of dust, and nucleosynthesis. Aims: We study the metal and dust content in the neutral ISM consistently in different environments, and assess the universality of recently discovered sequences of relative abundances. We also intend to assess the validity of [Zn/Fe] as a tracer of dust in the ISM. This has recently been cast into doubt based on observations of stellar abundances, and needs to be addressed before we can safely use it to study the ISM. Methods: In this letter we present a simple comparison of relative abundances observed in the neutral ISM in the Galaxy, the Magellanic Clouds, and damped Lyman-α absorbers (DLAs). The main novelty in this comparison is the inclusion of the Magellanic Clouds. Results: The same sequences of relative abundances are valid for the Galaxy, Magellanic Clouds, and DLAs. These sequences are driven by the presence of dust in the ISM and seem "universal". Conclusions: The metal and dust properties in the neutral ISM appear to follow a similar behaviour in different environments. This suggests that a dominant fraction of the dust budget is built up from grain growth in the ISM depending of the physical conditions and regardless of the star formation history of the system. In addition, the DLA gas behaves like the neutral ISM, at least from a chemical point of view. Finally, despite the deviations in [Zn/Fe] observed in stellar abundances, [Zn/Fe] is a robust dust tracer in the ISM of different environments, from the Galaxy to DLAs.

Indoor metallic pollution and children exposure in a mining city

International Nuclear Information System (INIS)

Barbieri, Enio; Fontúrbel, Francisco E.; Herbas, Cristian; Barbieri, Flavia L.; Gardon, Jacques

2014-01-01

Mining industries are known for causing strong environmental contamination. In most developing countries, the management of mining wastes is not adequate, usually contaminating soil, water and air. This situation is a source of concern for human settlements located near mining centers, especially for vulnerable populations such as children. The aim of this study was to assess the correlations of the metallic concentrations between household dust and children hair, comparing these associations in two different contamination contexts: a mining district and a suburban non-mining area. We collected 113 hair samples from children between 7 and 12 years of age in elementary schools in the mining city of Oruro, Bolivia. We collected 97 indoor dust samples from their households, as well as information about the children's behavior. Analyses of hair and dust samples were conducted to measure As, Cd, Pb, Sb, Sn, Cu and Zn contents. In the mining district, there were significant correlations between non-essential metallic elements (As, Cd, Pb, Sb and Sn) in dust and hair, but not for essential elements (Cu and Zn), which remained after adjusting for children habits. Children who played with dirt had higher dust-hair correlations for Pb, Sb, and Cu (P = 0.006; 0.022 and 0.001 respectively) and children who put hands or toys in their mouths had higher dust-hair correlations of Cd (P = 0.011). On the contrary, in the suburban area, no significant correlations were found between metallic elements in dust and children hair and neither children behavior nor gender modified this lack of associations. Our results suggest that, in a context of high metallic contamination, indoor dust becomes an important exposure pathway for children, modulated by their playing behavior. - Highlights: • Mining activities are an important source of environmental pollution. • Mining pollution contaminated also indoor homes, creating a risk to population. • Indoor dust and hair concentrations in As

Carpet-dust chemicals as measures of exposure: Implications of variability

Directory of Open Access Journals (Sweden)

Whitehead Todd P

2012-03-01

Full Text Available Abstract Background There is increasing interest in using chemicals measured in carpet dust as indicators of chemical exposures. However, investigators have rarely sampled dust repeatedly from the same households and therefore little is known about the variability of chemical levels that exist within and between households in dust samples. Results We analyzed 9 polycyclic aromatic hydrocarbons, 6 polychlorinated biphenyls, and nicotine in 68 carpet-dust samples from 21 households in agricultural communities of Fresno County, California collected from 2003-2005. Chemical concentrations (ng per g dust ranged from Conclusions Our findings suggest that attenuation bias should be relatively modest when using these semi-volatile carpet-dust chemicals as exposure surrogates in epidemiologic studies.

Bioaccessibility of metals in soils and dusts contaminated by marine antifouling paint particles

International Nuclear Information System (INIS)

Turner, Andrew; Singh, Nimisha; Richards, Jonathan P.

2009-01-01

Fragments of antifouling paint and environmental geosolids have been sampled from the island of Malta and analysed for total and bioaccessible metals. Total concentrations of Ba, Cd, Cu, Pb, Sn and Zn were two to three orders of magnitude higher in spent antifouling composites relative to respective values in background soils and road dusts. Paint fragments were visible in geosolids taken from the immediate vicinity of boat maintenance facilities and mass balance calculations, based on Ba as a paint tracer, suggested that the most contaminated soils, road dusts and boatyard dusts contained about 1%, 7% and 9%, respectively, of antifouling particles. Human bioaccessibilities of metals were evaluated in selected samples using a physiologically based extraction technique. Accessibilities of Cd, Cu, Pb and Zn in the most contaminated solids were sufficient to be cause for concern for individuals working in the boat repair industry and to the wider, local community. - Geosolids near boat maintenance facilities are contaminated by antifouling paint particles containing high concentrations of bioaccessible metals.

Bioaccessibility of metals in soils and dusts contaminated by marine antifouling paint particles

Energy Technology Data Exchange (ETDEWEB)

Turner, Andrew, E-mail: aturner@plymouth.ac.u [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Singh, Nimisha; Richards, Jonathan P. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

2009-05-15

Fragments of antifouling paint and environmental geosolids have been sampled from the island of Malta and analysed for total and bioaccessible metals. Total concentrations of Ba, Cd, Cu, Pb, Sn and Zn were two to three orders of magnitude higher in spent antifouling composites relative to respective values in background soils and road dusts. Paint fragments were visible in geosolids taken from the immediate vicinity of boat maintenance facilities and mass balance calculations, based on Ba as a paint tracer, suggested that the most contaminated soils, road dusts and boatyard dusts contained about 1%, 7% and 9%, respectively, of antifouling particles. Human bioaccessibilities of metals were evaluated in selected samples using a physiologically based extraction technique. Accessibilities of Cd, Cu, Pb and Zn in the most contaminated solids were sufficient to be cause for concern for individuals working in the boat repair industry and to the wider, local community. - Geosolids near boat maintenance facilities are contaminated by antifouling paint particles containing high concentrations of bioaccessible metals.

Pollution distribution and health risk assessment of heavy metals in indoor dust in Anhui rural, China.

Science.gov (United States)

Lin, Yuesheng; Fang, Fengman; Wang, Fei; Xu, Minglu

2015-09-01

Zn, Pb, Cu, Cr, V, Ni, Co, and As concentrations of indoor dust in Anhui rural were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The degrees of metal pollution in indoor dust ranked as follows: Zn > Pb > Cr > Cu > V > Ni > Co > As, on average. The arithmetic means of Zn, Pb, Cu, Cr, V, Ni, Co, and As were 427.17, 348.73, 107.05, 113.68, 52.64, 38.93, 10.29, and 4.46 mg/kg, respectively. These were higher than background values of Anhui soil for Zn, Pb, Cu, Cr, and Ni, especially for Pb with the mean value of 13.21 times the background value. Heavy metal concentrations of indoor dust were different from different rural areas. House type (bungalows or storied house), sweeping frequency, and external environment around the house (such as the road grade) affected heavy metal concentrations in indoor dust. The results of factor analysis and correlation analysis indicated that Cu, Cr, Ni, Zn, and Co concentrations were mainly due to interior paint, metal objects, and building materials. Pb and As concentrations were due to vehicle emissions. V concentration was mainly of natural source. Average daily doses for the exposure pathway of the studied heavy metals decreased in children in the following order: hand-to-mouth ingestion > dermal contact > inhalation. The non-carcinogenic risks of heavy metals ranked as Pb > V > Cr > Cu > Zn > As > Co > Ni, and the carcinogenic risks of metals decreased in the order of Cr > Co > As > Ni. The non-carcinogenic hazard indexes and carcinogenic risks of metals in indoor dust were both lower than the safe values.

Pollution and health risk of potentially toxic metals in urban road dust in Nanjing, a mega-city of China

International Nuclear Information System (INIS)

Liu, Enfeng; Yan, Ting; Birch, Gavin; Zhu, Yuxin

2014-01-01

Spatial variations in concentrations of a suite of potentially toxic metals (Ba, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and Ca in road dusts (n = 99) from urban trunk roads (TR) in Nanjing, a mega-city in China, were established. Metal pollution levels, sources and human health risk (non-carcinogenic) were studied. In contrast to previous studies, we labeled the indicative metals relating to non-exhaust traffic emissions by comparing metal pollution between crossroad and park road dusts, and then anthropogenic sources of metals in TR dusts were assessed combining their spatial pollution patterns, principal component analysis and Pb isotopic compositions. Results showed that the metals were enriched in TR dusts compared to background soil concentrations with mean enrichment factors (EFs) of 2.2–23, indicating considerable anthropogenic influence. The degrees of metal pollution ranged from minimal to extremely high and ranked by Ca > Cu > Pb ≈ Zn > Cr ≈ Fe > Ni ≈ Ba > Mn on average. Pollution of Cr, Cu, Fe, Mn, Ni, Pb and Zn in TR dusts resulted primarily from industrial emissions (e.g., coal combustion and smelting) and high pollution levels were found close to suburb industrial complexes, whereas pollution of Ba and Ca was mainly related to construction/demolition sources and was generally distributed homogeneously. The relatively minor contribution of non-exhaust traffic emissions to metal pollution in TR dusts was considered to be due to overwhelming industrial and construction/demolition contributions, as well as to the dilution effect of natural soil particles. Ingestion appears to be the major route of exposure for road dust for both adults and children, followed by dermal contact. The non-carcinogenic health risk resulting from exposure to the potentially toxic metals in TR dusts was within the safe level based on the Hazard Index (HI), except in pollution hotspots where exposure to Pb, Cr, and Cu may be hazardous to children. - Highlights: • Pollution and

Pollution and health risk of potentially toxic metals in urban road dust in Nanjing, a mega-city of China

Energy Technology Data Exchange (ETDEWEB)

Liu, Enfeng, E-mail: efliu@niglas.ac.cn [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Yan, Ting [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Birch, Gavin [School of Geosciences, University of Sydney, Sydney, NSW 2006 (Australia); Zhu, Yuxin [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China)

2014-04-01

Spatial variations in concentrations of a suite of potentially toxic metals (Ba, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and Ca in road dusts (n = 99) from urban trunk roads (TR) in Nanjing, a mega-city in China, were established. Metal pollution levels, sources and human health risk (non-carcinogenic) were studied. In contrast to previous studies, we labeled the indicative metals relating to non-exhaust traffic emissions by comparing metal pollution between crossroad and park road dusts, and then anthropogenic sources of metals in TR dusts were assessed combining their spatial pollution patterns, principal component analysis and Pb isotopic compositions. Results showed that the metals were enriched in TR dusts compared to background soil concentrations with mean enrichment factors (EFs) of 2.2–23, indicating considerable anthropogenic influence. The degrees of metal pollution ranged from minimal to extremely high and ranked by Ca > Cu > Pb ≈ Zn > Cr ≈ Fe > Ni ≈ Ba > Mn on average. Pollution of Cr, Cu, Fe, Mn, Ni, Pb and Zn in TR dusts resulted primarily from industrial emissions (e.g., coal combustion and smelting) and high pollution levels were found close to suburb industrial complexes, whereas pollution of Ba and Ca was mainly related to construction/demolition sources and was generally distributed homogeneously. The relatively minor contribution of non-exhaust traffic emissions to metal pollution in TR dusts was considered to be due to overwhelming industrial and construction/demolition contributions, as well as to the dilution effect of natural soil particles. Ingestion appears to be the major route of exposure for road dust for both adults and children, followed by dermal contact. The non-carcinogenic health risk resulting from exposure to the potentially toxic metals in TR dusts was within the safe level based on the Hazard Index (HI), except in pollution hotspots where exposure to Pb, Cr, and Cu may be hazardous to children. - Highlights: • Pollution and

Evaluation of some heavy metals loading in dust fall of three ...

African Journals Online (AJOL)

Generally for the three sites used, the heavy metal concentrations decreased in the following order: Mn>Zn>Pb>Ni>Cu>Cd. This implies that dust-fall in the parks are heavily loaded with some heavy metals that are of concentrations above Romania standard threshold limit for Cd and Pb while concentration values obtained ...

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

International Nuclear Information System (INIS)

Chen, Hao; Lu, Xinwei; Li, Loretta Y.; Gao, Tianning; Chang, Yuyu

2014-01-01

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

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

Energy Technology Data Exchange (ETDEWEB)

Gonzales, Patricia; Felix, Omar [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Alexander, Caitlin; Lutz, Eric [Division of Community, Environment, and Policy, Mel and Enid Zuckerman College of Public Health, University of Arizona, 1656 E. Mabel St., Tucson, AZ 85724 (United States); Ela, Wendell [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Eduardo Sáez, A., E-mail: esaez@arizona.edu [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States)

2014-09-15

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure.

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

International Nuclear Information System (INIS)

Gonzales, Patricia; Felix, Omar; Alexander, Caitlin; Lutz, Eric; Ela, Wendell; Eduardo Sáez, A.

2014-01-01

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure

Household mold and dust allergens: Exposure, sensitization and childhood asthma morbidity

International Nuclear Information System (INIS)

Gent, Janneane F.; Kezik, Julie M.; Hill, Melissa E.; Tsai, Eling; Li, De-Wei; Leaderer, Brian P.

2012-01-01

Background: Few studies address concurrent exposures to common household allergens, specific allergen sensitization and childhood asthma morbidity. Objective: To identify levels of allergen exposures that trigger asthma exacerbations in sensitized individuals. Methods: We sampled homes for common indoor allergens (fungi, dust mites (Der p 1, Der f 1), cat (Fel d 1), dog (Can f 1) and cockroach (Bla g 1)) for levels associated with respiratory responses among school-aged children with asthma (N=1233) in a month-long study. Blood samples for allergy testing and samples of airborne fungi and settled dust were collected at enrollment. Symptoms and medication use were recorded on calendars. Combined effects of specific allergen sensitization and level of exposure on wheeze, persistent cough, rescue medication use and a 5-level asthma severity score were examined using ordered logistic regression. Results: Children sensitized and exposed to any Penicillium experienced increased risk of wheeze (odds ratio [OR] 2.12 95% confidence interval [CI] 1.12, 4.04), persistent cough (OR 2.01 95% CI 1.05, 3.85) and higher asthma severity score (OR 1.99 95% CI 1.06, 3.72) compared to those not sensitized or sensitized but unexposed. Children sensitized and exposed to pet allergen were at significantly increased risk of wheeze (by 39% and 53% for Fel d 1>0.12 μg/g and Can f 1>1.2 μg/g, respectively). Increased rescue medication use was significantly associated with sensitization and exposure to Der p 1>0.10 μg/g (by 47%) and Fel d 1>0.12 μg/g (by 32%). Conclusion: Asthmatic children sensitized and exposed to low levels of common household allergens Penicillium, Der p 1, Fel d 1 and Can f 1 are at significant risk for increased morbidity. - Highlights: ► Few studies address concurrent allergen exposures, sensitization and asthma morbidity. ► Children with asthma were tested for sensitivity to common indoor allergens. ► Homes were sampled for these allergens and asthma

Biomonitoring and speciation of road dust for heavy metals using Calotropis procera and Delbergia sissoo

Directory of Open Access Journals (Sweden)

Santosh Kumar Prajapati

2012-12-01

Full Text Available The present study was conducted for identifying the important heavy metals present in the road dust and at the same time biomonitor them using Calotropis procera and Delbergia sissoo leaves. The study clearly indicated that both the plants can be used as biomonitor for As, Pb, Fe, V, Cd, Cr, Zn and Cu. The heavy metals were estimated using AAS-7000 (Shimadzu. Reason for selecting the plants were their abundance in the area and high air pollution indices. Presence of these heavy metals in the road dust can be attributed to the red soil and more importantly thermal power plants operating in the study area. Since plants are able to capture the road dust, they can also prevent the particulate pollution which is having adverse health impacts for humans.

Metal dust exposure and lung function deterioration among steel workers: an exposure-response relationship.

Science.gov (United States)

Hamzah, Nurul Ainun; Mohd Tamrin, Shamsul Bahri; Ismail, Noor Hassim

2016-07-01

Metallic dust is a heterogeneous substance with respiratory sensitizing properties. Its long term exposure adversely affected lung function, thus may cause acute or chronic respiratory diseases. A cross-sectional study was conducted in a steel factory in Terengganu, Malaysia to assess the metal dust exposure and its relationship to lung function values among 184 workers. Metal dust concentrations values (Co, Cr, and Ni) for each worker were collected using air personal sampling. Lung function values (FEV 1 , FVC, and %FEV 1 /FVC) were determined using spirometer. Exposure to cobalt and chromium were 1-3 times higher than permissible exposure limit (PEL) while nickel was not exceeding the PEL. Cumulative of chromium was the predictor to all lung function values (FEV 1 , FVC, and %FEV 1 /FVC). Frequency of using mask was positively associated with FVC (Adj b = 0.263, P = 0.011) while past respiratory illnesses were negatively associated with %FEV 1 /FVC (Adj b = -1.452, P = 0.026). Only few workers (36.4%) were found to wear their masks all times during the working hours. There was an exposure-response relationship of cumulative metal dust exposure with the deterioration of lung function values. Improvement of control measures as well as proper and efficient use or personal protection equipment while at work could help to protect the respiratory health of workers.

Metal Dust Exposure and Respiratory Health of Male Steel Work¬ers in Terengganu, Malaysia

OpenAIRE

Nurul Ainun HAMZAH; Shamsul Bahri MOHD TAMRIN; Noor Hassim ISMAIL

2015-01-01

Background: This cross sectional study was carried out to determine the relationship between metal dust exposure and respiratory health in male steel workers in Terengganu, Malaysia.Methods: Subjects were interviewed using a structured questionnaire from British Medical Research Council (BMRC) Questionnaire regarding respiratory symptoms and were examined their lung function using spirometer.Results: The mean trace metal dusts concentration TWA8 for cobalt and chromium in most of work unit ex...

Assessment of heavy metals in street dust in Kathmandu metropolitan city and their possible impacts on the environment

International Nuclear Information System (INIS)

Tamrakar, C.S.; Shakya, P.R.

2011-01-01

Street dust often contains elevated concentrations of heavy metals and can influence on environment and human health. Therefore, a study on the characteristics of heavy metals in street dusts at different localities was carried out in the metropolitan city of Kathmandu of Nepal. A total of 20 street dusts have been sampled from four sampling sites with various activities or characteristics such as mechanical workshops (MWK), motor parks (MPK), market areas (MKA) and residential areas (RDA) and analyzed for Zn, Pb, Ni, Cr and Cd using the atomic absorption spectrophotometric method. Results showed that street dust samples contained significant levels of the metals studied compared to the values from the control site. The variation in concentration of most of the heavy metals determined decreased in an order represented as MWK>MPK>MKA>RDA>Control. While the RDA and MKA give the same element abundance order as Zn > Pb > Ni > Cr > Cd, the MPK and MWK show different abundance order in some elemental contents. In all the street dusts, zinc is the most available and labile element followed by lead. From the place of low activity (RDA) to the place of high activity (MWK), the metal concentrations in street dusts varied from 55.4-419.3 mu g/sup -1/ for Zn, 12.3-116.8 mu g/sup -1/ for Pb, 4.9-86.3 mu /sup -1/ for Ni, 1.4-14.3 mu g/sup -1/ for Cr and 0.3-39.6 mu g/sup -1/ for Cd respectively. Results indicate that the metal pollutants in street dusts could significantly contribute to deteriorate the environmental status of the city of Kathmandu metropolis. (author)

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

Directory of Open Access Journals (Sweden)

Samira Norouzi

2015-07-01

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

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

Science.gov (United States)

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

2016-01-01

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

Risk Assessment and Implication of Human Exposure to Road Dust Heavy Metals in Jeddah, Saudi Arabia.

Science.gov (United States)

Shabbaj, Ibrahim I; Alghamdi, Mansour A; Shamy, Magdy; Hassan, Salwa K; Alsharif, Musaab M; Khoder, Mamdouh I

2017-12-26

Data dealing with the assessment of heavy metal pollution in road dusts in Jeddah, Saudi Arabia and its implication to human health risk of human exposure to heavy metals, are scarce. Road dusts were collected from five different functional areas (traffic areas (TA), parking areas (PA), residential areas (RA), mixed residential commercial areas (MCRA) and suburban areas (SA)) in Jeddah and one in a rural area (RUA) in Hada Al Sham. We aimed to measure the pollution levels of heavy metals and estimate their health risk of human exposure applying risk assessment models described by United States Environmental Protection Agency (USEPA). Using geo-accumulation index (I geo ), the pollution level of heavy metals in urban road dusts was in the following order Cd > As > Pb > Zn > Cu > Ni > Cr > V > Mn > Co > Fe. Urban road dust was found to be moderately to heavily contaminated with As, Pb and Zn, and heavily to extremely contaminated with Cd. Calculation of enrichment factor (EF) revealed that heavy metals in TA had the highest values compared to that of the other functional areas. Cd, As, Pb, Zn and Cu were severely enriched, while Mn, V, Co, Ni and Cr were moderately enriched. Fe was considered as a natural element and consequently excluded. The concentrations of heavy metals in road dusts of functional areas were in the following order: TA > PA > MCRA > SA > RA > RUA. The study revealed that both children and adults in all studied areas having health quotient (HQ) exposure route was ingestion. The cancer risk for children and adults from exposure to Pb, Cd, Co, Ni, and Cr was found to be negligible (≤1 × 10 -6 ).

Assessment of heavy metal contamination of dust at some selected fuel filling stations in Accra

International Nuclear Information System (INIS)

Afrifa, C. G.

2011-07-01

Heavy metal contaminated dust particles of fuel filling stations can be re-suspended into the ambient air and serve as a source of atmospheric pollution since the fine particles are aerodynamic and have longer life time in ambient air. This can cause ill-health effect on the fuel attendants and residents within the neighbourhood especially infants and the aged who are more vulnerable. In spite of this, not much research has been done on heavy metal contamination of dust at fuel filling stations. In this study, 55 dust samples were collected from six fuel filling stations in the Ga-East district and Accra Metropolitan assembly, both in Accra, in order to assess the levels of contamination of heavy metals; their possible sources and the human health risk associated with them. The dust samples were divided into two parts with one part sieved into four fractions using metric mesh sizes 500 µm, 200µm, 100µm and 45 µm, and pulverised. Total concentrations of heavy metals (Si, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Br, Rb, Sr, Y, Zr and Pb) were determined in the dust samples using energy dispersive X-ray fluorescence analysis. The pollution indices; enrichment factors (EF), index of geoaccumulation (Igeo), contamination factor (CF) and pollution load index (PLI) were used to identify possible levels of pollution from anthropogenic sources. The possible sources of metals were also identified with principal component analysis. Noncancer effect of children and adults due to exposure to dust from these fuel filling stations were also estimated. For the three fuelling areas, the average concentrations of V, Cr, Ni and Cu exceeded the acceptable values in common soil in the <45 µm fraction. The average concentration of Zn however exceeded the acceptable value only at the mixed-fuel fuelling area whereas the average concentration of Pb was within the acceptable value for all three fuelling areas. The dust samples showed moderate to significant enrichments for V, Cu, Br

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-06-01

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

Survey of metals on antimicrobial and deodorant agents in household Necessities; Mukikei kokinsei kakoseihin no shiyojittai

Energy Technology Data Exchange (ETDEWEB)

Kan, Teruo

1999-11-01

It measured the metal bearing quantity in household necessities in order to clarify use actual condition of the metal system drug. And, it tried the detection of the drug used from detected metal. Too there is the report until now in the investigation of the metallic element in household necessities. However, metals examined this time are silver and zinc, four of copper and aluminum that it says that it has the antimicrobial action and is Key element of inorganic system antimicrobial agent. And, it carried out the analysis by inductive coupling plasma emission analysis method, after the wet digestion of the sample was done. (NEDO)

An index for estimating the potential metal pollution contribution to atmospheric particulate matter from road dust in Beijing.

Science.gov (United States)

Zhao, Hongtao; Shao, Yaping; Yin, Chengqing; Jiang, Yan; Li, Xuyong

2016-04-15

The resuspension of road dust from street surfaces could be a big contributor to atmospheric particulate pollution in the rapid urbanization context in the world. However, to date what its potential contribution to the spatial pattern is little known. Here we developed an innovative index model called the road dust index (RIatmospheric suspended particles. The factors were ranked and weighted based on road dust characteristics (the amounts, grain sizes, and mobilities of the road dust, and the concentrations and toxicities of metals in the road dust). We then applied the RIatmospheric suspended particles. The results demonstrated that the road dust in urban areas has higher potential risk of metal to atmospheric particles than that in rural areas. The RIatmospheric suspended particles and for controlling atmospheric particulate pollution caused by road dust emissions. Copyright © 2016 Elsevier B.V. All rights reserved.

Corrosion resistance of Ni-50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

Energy Technology Data Exchange (ETDEWEB)

Saaedi, J. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada); Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Arabi, H.; Mirdamadi, S.; Ghorbani, H. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Coyle, T.W. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

2011-09-15

Metal dusting attack has been examined after three 168 h cycles on two Ni-50Cr coatings with different microstructures deposited on 310S alloy substrates by the high velocity oxy-fuel (HVOF) thermal-spray process. Metal dusting in uncoated 310S alloy specimens was found to be still in the initiation stage after 504 h of exposure in the 50H{sub 2}:50CO gas environment at 620 C. Dense Ni-50Cr coatings offered suitable resistance to metal dusting. Metal dusting was observed in the 310S substrates adjacent to pores at the interface between the substrate and a porous Ni-50Cr coating. The porosity present in the as-deposited coatings was shown to introduce a large variability into coating performance. Carbon formed by decomposition of the gaseous species accumulated in the surface pores and resulted in the dislodgement of surface splats due to stresses generated by the volume changes. When the corrosive gas atmosphere was able to penetrate through the interconnected pores and reach the coating-substrate interface, the 310S substrate was carburized, metal dusting attack occurred, and the resulting formation of coke in the pores led to local failure of the coating. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

Energy Technology Data Exchange (ETDEWEB)

Ghorbani, H. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Rashidi, A.M., E-mail: Rashidiam@ripi.ir [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Blvd. Azadi Sport Complex, P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Rastegari, S.; Mirdamadi, S. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Alaei, M. [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Blvd. Azadi Sport Complex, P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of)

2011-05-15

Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

International Nuclear Information System (INIS)

Ghorbani, H.; Rashidi, A.M.; Rastegari, S.; Mirdamadi, S.; Alaei, M.

2011-01-01

Research highlights: → Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. → Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. → Optimum growth condition is CO/H 2 = 1/1, 100 cm 3 /min, at 620 o C under long term repetitive thermal cycling. → Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H 2 = 1/1, total gas flow rate 100 cm 3 /min, at 620 o C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

Indoor metallic pollution and children exposure in a mining city

Energy Technology Data Exchange (ETDEWEB)

Barbieri, Enio, E-mail: enniobg@gmail.com [IRD (Institut de Recherche pour le Développement), La Paz (Bolivia, Plurinational State of); Fontúrbel, Francisco E. [Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago de Chile (Chile); Herbas, Cristian [Instituto IGEMA, Universidad Mayor de San Andrés, La Paz (Bolivia, Plurinational State of); Barbieri, Flavia L. [IRD (Institut de Recherche pour le Développement), La Paz (Bolivia, Plurinational State of); Universidad Mayor de San Andrés, SELADIS (Instituto de Servicios de Laboratorio para el Diagnóstico e Investigación en Salud), La Paz (Bolivia, Plurinational State of); Berlin School of Public Health, Charité Universitätsmedizin, Berlin (Germany); Gardon, Jacques [IRD (Institut de Recherche pour le Développement), La Paz (Bolivia, Plurinational State of); Universidad Mayor de San Andrés, SELADIS (Instituto de Servicios de Laboratorio para el Diagnóstico e Investigación en Salud), La Paz (Bolivia, Plurinational State of); IRD, HSM, Montpellier (France)

2014-07-01

Mining industries are known for causing strong environmental contamination. In most developing countries, the management of mining wastes is not adequate, usually contaminating soil, water and air. This situation is a source of concern for human settlements located near mining centers, especially for vulnerable populations such as children. The aim of this study was to assess the correlations of the metallic concentrations between household dust and children hair, comparing these associations in two different contamination contexts: a mining district and a suburban non-mining area. We collected 113 hair samples from children between 7 and 12 years of age in elementary schools in the mining city of Oruro, Bolivia. We collected 97 indoor dust samples from their households, as well as information about the children's behavior. Analyses of hair and dust samples were conducted to measure As, Cd, Pb, Sb, Sn, Cu and Zn contents. In the mining district, there were significant correlations between non-essential metallic elements (As, Cd, Pb, Sb and Sn) in dust and hair, but not for essential elements (Cu and Zn), which remained after adjusting for children habits. Children who played with dirt had higher dust-hair correlations for Pb, Sb, and Cu (P = 0.006; 0.022 and 0.001 respectively) and children who put hands or toys in their mouths had higher dust-hair correlations of Cd (P = 0.011). On the contrary, in the suburban area, no significant correlations were found between metallic elements in dust and children hair and neither children behavior nor gender modified this lack of associations. Our results suggest that, in a context of high metallic contamination, indoor dust becomes an important exposure pathway for children, modulated by their playing behavior. - Highlights: • Mining activities are an important source of environmental pollution. • Mining pollution contaminated also indoor homes, creating a risk to population. • Indoor dust and hair concentrations

Searching for dust around hyper metal poor stars

International Nuclear Information System (INIS)

Venn, Kim A.; Divell, Mike; Starkenburg, Else; Puzia, Thomas H.; Côté, Stephanie; Lambert, David L.

2014-01-01

We examine the mid-infrared fluxes and spectral energy distributions for stars with iron abundances [Fe/H] <–5, and other metal-poor stars, to eliminate the possibility that their low metallicities are related to the depletion of elements onto dust grains in the formation of a debris disk. Six out of seven stars examined here show no mid-IR excesses. These non-detections rule out many types of circumstellar disks, e.g., a warm debris disk (T ≤ 290 K), or debris disks with inner radii ≤1 AU, such as those associated with the chemically peculiar post-asymptotic giant branch spectroscopic binaries and RV Tau variables. However, we cannot rule out cooler debris disks, nor those with lower flux ratios to their host stars due to, e.g., a smaller disk mass, a larger inner disk radius, an absence of small grains, or even a multicomponent structure, as often found with the chemically peculiar Lambda Bootis stars. The only exception is HE0107-5240, for which a small mid-IR excess near 10 μm is detected at the 2σ level; if the excess is real and associated with this star, it may indicate the presence of (recent) dust-gas winnowing or a binary system.

Searching for dust around hyper metal poor stars

Energy Technology Data Exchange (ETDEWEB)

Venn, Kim A.; Divell, Mike; Starkenburg, Else [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2 (Canada); Puzia, Thomas H. [Institute of Astrophysics, Pontificia Universidad Catolica de Chile, Av. Vicuna Mackenna 4860, 7820436 Macul, Santiago (Chile); Côté, Stephanie [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Lambert, David L., E-mail: kvenn@uvic.ca [McDonald Observatory and the Department of Astronomy, University of Texas at Austin, RLM 15.308, Austin, TX 78712 (United States)

2014-08-20

We examine the mid-infrared fluxes and spectral energy distributions for stars with iron abundances [Fe/H] <–5, and other metal-poor stars, to eliminate the possibility that their low metallicities are related to the depletion of elements onto dust grains in the formation of a debris disk. Six out of seven stars examined here show no mid-IR excesses. These non-detections rule out many types of circumstellar disks, e.g., a warm debris disk (T ≤ 290 K), or debris disks with inner radii ≤1 AU, such as those associated with the chemically peculiar post-asymptotic giant branch spectroscopic binaries and RV Tau variables. However, we cannot rule out cooler debris disks, nor those with lower flux ratios to their host stars due to, e.g., a smaller disk mass, a larger inner disk radius, an absence of small grains, or even a multicomponent structure, as often found with the chemically peculiar Lambda Bootis stars. The only exception is HE0107-5240, for which a small mid-IR excess near 10 μm is detected at the 2σ level; if the excess is real and associated with this star, it may indicate the presence of (recent) dust-gas winnowing or a binary system.

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

Directory of Open Access Journals (Sweden)

Jie Yang

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

Household mold and dust allergens: Exposure, sensitization and childhood asthma morbidity

Energy Technology Data Exchange (ETDEWEB)

Gent, Janneane F., E-mail: janneane.gent@yale.edu [Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, One Church Street, 6th Floor, New Haven, CT 06510 (United States); Kezik, Julie M., E-mail: julie.colburn@yale.edu [Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, One Church Street, 6th Floor, New Haven, CT 06510 (United States); Hill, Melissa E., E-mail: melissa.hill@yale.edu [Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, One Church Street, 6th Floor, New Haven, CT 06510 (United States); Tsai, Eling, E-mail: tsai.umiami@gmail.com [Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, One Church Street, 6th Floor, New Haven, CT 06510 (United States); Li, De-Wei, E-mail: DeWei.Li@ct.gov [Connecticut Agricultural Experiment Station, Valley Laboratory, 153 Cook Hill Road, Windsor, CT 06095 (United States); Leaderer, Brian P., E-mail: brian.leaderer@yale.edu [Yale Center for Perinatal, Pediatric and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, One Church Street, 6th Floor, New Haven, CT 06510 (United States)

2012-10-15

Background: Few studies address concurrent exposures to common household allergens, specific allergen sensitization and childhood asthma morbidity. Objective: To identify levels of allergen exposures that trigger asthma exacerbations in sensitized individuals. Methods: We sampled homes for common indoor allergens (fungi, dust mites (Der p 1, Der f 1), cat (Fel d 1), dog (Can f 1) and cockroach (Bla g 1)) for levels associated with respiratory responses among school-aged children with asthma (N=1233) in a month-long study. Blood samples for allergy testing and samples of airborne fungi and settled dust were collected at enrollment. Symptoms and medication use were recorded on calendars. Combined effects of specific allergen sensitization and level of exposure on wheeze, persistent cough, rescue medication use and a 5-level asthma severity score were examined using ordered logistic regression. Results: Children sensitized and exposed to any Penicillium experienced increased risk of wheeze (odds ratio [OR] 2.12 95% confidence interval [CI] 1.12, 4.04), persistent cough (OR 2.01 95% CI 1.05, 3.85) and higher asthma severity score (OR 1.99 95% CI 1.06, 3.72) compared to those not sensitized or sensitized but unexposed. Children sensitized and exposed to pet allergen were at significantly increased risk of wheeze (by 39% and 53% for Fel d 1>0.12 {mu}g/g and Can f 1>1.2 {mu}g/g, respectively). Increased rescue medication use was significantly associated with sensitization and exposure to Der p 1>0.10 {mu}g/g (by 47%) and Fel d 1>0.12 {mu}g/g (by 32%). Conclusion: Asthmatic children sensitized and exposed to low levels of common household allergens Penicillium, Der p 1, Fel d 1 and Can f 1 are at significant risk for increased morbidity. - Highlights: Black-Right-Pointing-Pointer Few studies address concurrent allergen exposures, sensitization and asthma morbidity. Black-Right-Pointing-Pointer Children with asthma were tested for sensitivity to common indoor allergens

Pesticides in house dust from urban and farmworker households in California: an observational measurement study

Directory of Open Access Journals (Sweden)

McKone Thomas E

2011-03-01

Full Text Available Abstract Background Studies report that residential use of pesticides in low-income homes is common because of poor housing conditions and pest infestations; however, exposure data on contemporary-use pesticides in low-income households is limited. We conducted a study in low-income homes from urban and agricultural communities to: characterize and compare house dust levels of agricultural and residential-use pesticides; evaluate the correlation of pesticide concentrations in samples collected several days apart; examine whether concentrations of pesticides phased-out for residential uses, but still used in agriculture (i.e., chlorpyrifos and diazinon have declined in homes in the agricultural community; and estimate resident children's pesticide exposures via inadvertent dust ingestion. Methods In 2006, we collected up to two dust samples 5-8 days apart from each of 13 urban homes in Oakland, California and 15 farmworker homes in Salinas, California, an agricultural community (54 samples total. We measured 22 insecticides including organophosphates (chlorpyrifos, diazinon, diazinon-oxon, malathion, methidathion, methyl parathion, phorate, and tetrachlorvinphos and pyrethroids (allethrin-two isomers, bifenthrin, cypermethrin-four isomers, deltamethrin, esfenvalerate, imiprothrin, permethrin-two isomers, prallethrin, and sumithrin, one phthalate herbicide (chlorthal-dimethyl, one dicarboximide fungicide (iprodione, and one pesticide synergist (piperonyl butoxide. Results More than half of the households reported applying pesticides indoors. Analytes frequently detected in both locations included chlorpyrifos, diazinon, permethrin, allethrin, cypermethrin, and piperonyl butoxide; no differences in concentrations or loadings were observed between locations for these analytes. Chlorthal-dimethyl was detected solely in farmworker homes, suggesting contamination due to regional agricultural use. Concentrations in samples collected 5-8 days apart in

Impact of dust filter installation in ironworks and construction on brownfield area on the toxic metal concentration in street and house dust (Celje, Slovenia).

Science.gov (United States)

Zibret, Gorazd

2012-05-01

This article presents the impact of the ecological investment in ironworks (dust filter installation) and construction works at a highly contaminated brownfield site on the chemical composition of household dust (HD) and street sediment (SS) in Celje, Slovenia. The evaluation is based on two sampling campaigns: the first was undertaken 1 month before the ecological investment became operational and the second 3 years later. The results show that dust filter installations reduced the content of Co, Cr, Fe, Mn, Mo, W and Zn on average by 58% in HD and by 51% in SS. No reduction was observed at sampling points in the upwind direction from the ironworks. By contrast, the impact of the construction works on the highly contaminated brownfield site was detected by a significant increase (on average by 37%) of elements connected to the brownfield contamination in SS. Such increase was not detected in HD.

Carbon formation and metal dusting in hot-gas cleanup systems of coal gasifiers

Energy Technology Data Exchange (ETDEWEB)

Judkins, R.R.; Tortorelli, P.F.; Judkins, R.R.; DeVan, J.H.; Wright, I.G. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1995-11-01

The product gas resulting from the partial oxidation of Carboniferous materials in a gasifier is typically characterized by high carbon and sulfur, but low oxygen, activities and, consequently, severe degradation of the structural and functional materials can occur. The objective of this task was to establish the potential risks of carbon deposition and metal dusting in advanced coal gasification processes by examining the current state of knowledge regarding these phenomena, making appropriate thermochemical calculations for representative coal gasifiers, and addressing possible mitigation methods. The paper discusses carbon activities, iron-based phase stabilities, steam injection, conditions that influence kinetics of carbon deposition, and influence of system operating parameters on carbon deposition and metal dusting.

Saharan dust - a carrier of persistent organic pollutants, metals and microbes to the Caribbean?

Directory of Open Access Journals (Sweden)

V.H Garrison

2006-12-01

Full Text Available An international team of scientists from government agencies and universities in the United States, U.S. Virgin Islands (USVI, Trinidad & Tobago, the Republic of Cape Verde, and the Republic of Mali (West Africa is working together to elucidate the role Saharan dust may play in the degradation of Caribbean ecosystems. The first step has been to identify and quantify the persistent organic pollutants (POPs, trace metals, and viable microorganisms in the atmosphere in dust source areas of West Africa, and in dust episodes at downwind sites in the eastern Atlantic (Cape Verde and the Caribbean (USVI and Trinidad & Tobago. Preliminary findings show that air samples from Mali contain a greater number of pesticides, polychlorinated biphenyls (PCBs and polycyclic aromatic hydrocarbons (PAHs and in higher concentrations than the Caribbean sites. Overall, POP concentrations were similar in USVI and Trinidad samples. Trace metal concentrations were found to be similar to crustal composition with slight enrichment of lead in Mali. To date, hundreds of cultureable micro-organisms have been identified from Mali, Cape Verde, USVI, and Trinidad air samples. The sea fan pathogen, Aspergillus sydowii, has been identified in soil from Mali and in air samples from dust events in the Caribbean. We have shown that air samples from a dust-source region contain orders of magnitude more cultureable micro-organisms per volume than air samples from dust events in the Caribbean, which in turn contain 3-to 4-fold more cultureable microbes than during non-dust conditions. Rev. Biol. Trop. 54 (Suppl. 3: 9-21. Epub 2007 Jan. 15.

Metals recovery of spent household batteries using a hydrometallurgical process

International Nuclear Information System (INIS)

Souza, K.P.; Tenorio, J.A.S.

2010-01-01

The objective of the work is to study a method for metals recovery from a sample composed by a mixture of the main types of spent household batteries. Segregation of the main metals is investigated using a treatment route consisting of the following steps: manual identified and dismantling, grinding, electric furnace reduction, acid leaching and selective precipitation with sodium hydroxide with and without hydrogen peroxide. Before and after precipitations the solutions had been analyzed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP/OES) and the precipitated analyzed by Scanning Electron Microscopy (SEM) with Spectrometry of Energy Dispersion Spectroscopy (EDS). The results had indicated that the great majority of metals had been precipitated in pHs studied, also had co-precipitation or simultaneous precipitation of metals in some pHs. (author)

Dust Evolution in Low-Metallicity Environments: Bridging the Gap Between Local Universe and Primordial Galaxies

Science.gov (United States)

Galliano, Frederic; Barlow, Mike; Bendo, George; Boselli, Alessandro; Buat, Veronique; Chanial, Pierre; Clements, David; Davies, Jon; Eales, Steve; Gomez, Haley; Isaak, Kate; Madden, Suzanne; Page, Mathew; Perez Fournon, Ismael; Sauvage, Marc; Spinoglio, Luigi; Vaccari, Mattia; Wilson, Christine

2008-03-01

The local galaxy Science Advisory Group (SAG 2) in the Herschel/SPIRE consortium, has constructed a Guaranteed Time Key Program using the PACS and SPIRE insruments to obtain 60 to 550 micron photometry of a statistically significant sample of 51 dwarf galaxies in our local universe chosen to cover an impressivly broad range of physical conditions. Here we propose the necessary complementary IRAC, MIPS and IRS Spitzer observations which together with the Herschel GT database will provide a rich database to the community to perform the dust and gas analyses in unprecedented detail in low metallicity galaxies ranging between 1/50 to 1 solar metallicity. Due to their chemical youth, and to the extreme conditions they experience, low metallicity environments constitute a keystone to understand dust evolution. The primary goal of this combined Herschel and Spitzer project is to study in details the physical processes at play within the ISM of these galaxies. We will take advantage of the powerful combination of Spitzer, Herschel and ancillary data to decompose the SED into the emission coming from the main phases of the ISM. Such a decomposition will provide reliable estimate of the abundances of the principal dust species, as a fonction of metallicity and physical conditions. These results will be exploited to compare the various evolutionary processes affecting the dust content of galaxies. All these outstanding scientific advances will be the true legacy value that this project brings to the community.

Trace-metal concentrations in African dust: effects of long-distance transport and implications for human health

Science.gov (United States)

Garrison, Virginia; Lamothe, Paul; Morman, Suzette; Plumlee, Geoffrey S.; Gilkes, Robert; Prakongkep, Nattaporn

2010-01-01

The Sahara and Sahel lose billions of tons of eroded mineral soils annually to the Americas and Caribbean, Europe and Asia via atmospheric transport. African dust was collected from a dust source region (Mali, West Africa) and from downwind sites in the Caribbean [Trinidad-Tobago (TT) and U.S. Virgin Islands (VI)] and analysed for 32 trace-elements. Elemental composition of African dust samples was similar to that of average upper continental crust (UCC), with some enrichment or depletion of specific trace-elements. Pb enrichment was observed only in dust and dry deposition samples from the source region and was most likely from local use of leaded gasoline. Dust particles transported long-distances (VI and TT) exhibited increased enrichment of Mo and minor depletion of other elements relative to source region samples. This suggests that processes occurring during long-distance transport of dust produce enrichment/depletion of specific elements. Bioaccessibility of trace-metals in samples was tested in simulated human fluids (gastric and lung) and was found to be greater in downwind than source region samples, for some metals (e.g., As). The large surface to volume ratio of the dust particles (<2.5 µm) at downwind sites may be a factor.

Allergens in household dust and serological indicators of atopy and sensitization in Detroit children with history-based evidence of asthma.

Science.gov (United States)

Williams, Ann Houston; Smith, James Travis; Hudgens, Edward E; Rhoney, Scott; Ozkaynak, Halûk; Hamilton, Robert G; Gallagher, Jane E

2011-09-01

Home exposure to allergens is an important factor in the development of sensitization and subsequent exacerbations of allergic asthma. We investigated linkages among allergen exposure, immunological measurements, and asthma by examining (1) reservoir dust allergen levels in homes, (2) associations between presence of allergens in homes and sensitization status of resident children, and (3) associations between asthma status and total IgE, atopy (by Phadiatop), and positive allergen-specific tests. The study protocol was approved by Institutional Review Boards (IRBs) of the University of North Carolina Chapel Hill; Westat, Inc.; and the US Environmental Protection Agency Human Research Protocol Office. Data were collected from questionnaires, serum analyses, and household vacuum dust. Children (n = 205) were predominately African American (AA) (85.4%) and 51.6% were asthmatic. Sera from 185 children and home dust samples (n = 141) were analyzed for total and specific IgE antibodies to allergens from cat and dog dander, cockroach, dust mites, mice, rats, and molds. Sixty percent of the homes had detectable levels of three or more dust allergens. The proportions of children with positive allergen-specific IgE tests were dust mite (32%), dog (28%), cat (23%), cockroach (18%), mouse (5%), rat (4%), and molds (24-36%). Children testing positive to a single allergen also had positive responses to other allergens. Those children with positive serum tests for cat, dog, and dust mite lived in homes with detectable levels of cat (51%), dog (90%), and dust mite (Der f 1) (92%) allergens. Correlations between children's specific IgE levels and dust levels were linearly related for dog (p pets, pests, and molds) would be more successful than any approach that aimed at reducing one type of allergen.

Deposition of heavy metals from dust fallout in selected areas of Eastern Slovakia

Directory of Open Access Journals (Sweden)

Pavel Slančo

2005-11-01

Full Text Available The paper deals with an evaluation of the deposition of selected heavy metals in the form of a detailed analysis of the dust fallout. The loaded areas of Nižná Slaná and Jelšava with the mining and mineral processing industry of siderite ore and magnesite, the area of Krompachy with the copper metal works, the municipal and industrial environs of Košice and relatively clean area of the National Park of Slovak Paradise were monitored and compared. The results have shown significant differences in the qualitative and quantitative effect on the monitored areas. The values of heavy metals content in the dust fallout of the loaded areas exceeded by order the values detected in the Slovak Paradise. As to the mining areas of Nižná Slaná and Jelšava, the highest content of heavy metals was recorded in the case of Mn and As. The metallurgical area of Krompachy is mostly loaded by Cu, Pb, As and Cd..

Heavy Metal Concentrations in Ceiling Fan Dusts Sampled at Schools Around Serdang Area, Selangor

International Nuclear Information System (INIS)

Yap, C.K.; Krishnan, T.; Chew, W.

2011-01-01

In this study, ceiling fan dust samples were collected from three schools in the district of Serdang Selangor, Malaysia. The sampled dust were analysed for the concentrations of Cd, Cu, Fe, Ni, Pb and Zn. The heavy metal ranges found in all the schools were 2.96-7.74 μg/ g dry weight for Cd, 75-442 μg/ g dry weight for Cu, 3445-3852 μg/ g dry weight for Fe, 24-66 μg/ g dry weight for Ni, 140-734 μg/ g dry weight for Pb and 439-880 μg/ g dry weight for Zn. SMK Seri Serdang School was found to have elevated concentrations of Cd, Cu, Ni, Pb, and Zn which indicated the anthropogenic sources of the study sites. In comparison to other reported studies in the literature, the maximum levels of Cd, Cu, Ni, and Pb were comparable or higher to those cities reported. Therefore, more monitoring studies should be conducted in future since dusts could be related to human health hazards and the dusts can be used as a potential monitoring tool for heavy metal pollution in the atmosphere. (author)

The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

DEFF Research Database (Denmark)

Sparre, M.; Hartoog, O. E.; Krühler, T.

2014-01-01

Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio and extinction of the GRB host...

Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

Energy Technology Data Exchange (ETDEWEB)

Taylor, Mark Patrick, E-mail: mark.taylor@mq.edu.au; Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

2014-11-15

Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m{sup 2}) with the highest lead in surface dust (59,900 μg/m{sup 2}) and post-play hand wipes (60,900 μg/m{sup 2}) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust.

Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

International Nuclear Information System (INIS)

Taylor, Mark Patrick; Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

2014-01-01

Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m 2 ) with the highest lead in surface dust (59,900 μg/m 2 ) and post-play hand wipes (60,900 μg/m 2 ) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ( 206 Pb/ 207 Pb, 208 Pb/ 207 Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust

The Role of Desert-Dust Metals in the Pathobiology of Gulf War Illness

Science.gov (United States)

2017-10-01

DNA probes, animal models ); • clinical interventions; • new business creation; and • other. 7. PARTICIPANTS & OTHER COLLABORATING... disrupted resulting in extensive oxidative damage and neurological dysfunction. In Year 1 of this 3 year project we have established and characterized...BBB) allowing metals solubilized from inhaled desert dust particles to enter the brain. As a consequence, normal metal homeostasis is disrupted

Estimation of heavy metals in dust fall samples from three different industrial areas of Karachi

International Nuclear Information System (INIS)

Hashmi, D.R.; Khan, F.A.; Shareef, A.; Bano, A.B.; Munshi, A.B.

2010-01-01

The study of accumulation of heavy metals, Fe, Cu, Mn, Zn, Pb and Cd, in the dust fall samples, collected from three selected industrial areas of Karachi, showed the level of heavy metals to decrease gradually from sites of high activity to those of low activity such as from roundabouts to main roads to side roads. Concentration of heavy metal showed a variation of the order Fe>Zn>Pb>Mn>Cu>Cd. Iron had the highest concentration in all the sampling areas in the range of 1.947 +- 0.00 to 30.039 +- 0.01 mg/g. Lower values were observed for Cd with respective ranges of 0.001 +- 0.00 to 0.009 +- 0.01 mg/g. The results suggested that heavy metal pollution in the dust fall samples of industrial areas may be due to automobile and industrial exhaust from different industrial units. (author)

House dust and storage mite contamination of dry dog food stored in open bags and sealed boxes in 10 domestic households.

Science.gov (United States)

Gill, Christina; McEwan, Neil; McGarry, John; Nuttall, Tim

2011-04-01

Dry pet food is a potential source of exposure to house dust and storage mite allergens in canine atopic dermatitis. This study evaluated contamination of house dust and dry dog food stored in paper bags, sealable plastic bags and sealable plastic boxes in 10 households for 90 days using Acarex(®) tests for guanine, a Der p 1 ELISA and mite flotation. Acarex(®) tests were negative in all the food samples but positive in all the house dust samples. The Der p 1 levels and mite numbers significantly increased in food from paper bags (P = 0.0073 and P = 0.02, respectively), but not plastic bags or boxes. Mite numbers and Der p 1 levels were 10-1000 times higher in house dust than the corresponding food samples (P bags (P = 0.003), and mite numbers in house dust and food from the paper bags (P = 0.0007). Bedding and carpets were significantly associated with Der p 1 levels in house dust (P = 0.015 and P = 0.01, respectively), and food from the paper (both P = 0.02) and plastic bags (P = 0.03 and P = 0.04, respectively). Mites were identified in six of 10 paper bag, three of 10 plastic bag, one of 10 plastic box and nine of 10 house dust samples. These comprised Dermatophagoides (54%), Tyrophagus (10%; all from food) and unidentified mites (36%). Storage of food in sealable plastic boxes largely prevented contamination for 3 months. Exposure to mites and mite proteins in all the stored food, however, appeared to be trivial compared with house dust. © 2010 The Authors. Journal compilation © 2010 ESVD and ACVD.

Spatial distribution, environmental risk and source of heavy metals in street dust from an industrial city in semi-arid area of China

Directory of Open Access Journals (Sweden)

Han Xiufeng

2017-06-01

Full Text Available Environmental risks associated with Co, Cr, Cu, Mn, Ni, Pb, V and Zn in street dust collected from Baotou, a medium-sized industrial city in a semi-arid area of northwest China, were assessed by using enrichment factor and the potential ecological index. Their spatial distributions and sources in the dust were analyzed on the basis of geostatistical methods and multivariate statistical analysis, respectively. The results indicate that street dust in Baotou has elevated heavy metal concentrations, especially of Co, Cr, Cu, Pb and Zn. Co in the dust was significantly enriched. Cr and Pb were from moderate to significant enrichment. Cu and Zn were from minimal to moderate enrichment, whereas Mn, Ni and V in the dust were from deficient to minimal enrichment. The ecological risk levels of Co and Pb in the dust were moderate to considerable and low to moderate, respectively, whereas those of other heavy metals studied in the dust presented low ecological risk. Different distribution patterns were found among the analyzed heavy metals. Three main sources of these heavy metals were identified. Cr, Mn, Ni and V originated from nature and industrial activities. Cu, Pb and Zn derived mainly from traffic sources, and Co was mainly from construction sources.

Shotgun pyrosequencing metagenomic analyses of dusts from swine confinement and grain facilities.

Science.gov (United States)

Boissy, Robert J; Romberger, Debra J; Roughead, William A; Weissenburger-Moser, Lisa; Poole, Jill A; LeVan, Tricia D

2014-01-01

Inhalation of agricultural dusts causes inflammatory reactions and symptoms such as headache, fever, and malaise, which can progress to chronic airway inflammation and associated diseases, e.g. asthma, chronic bronchitis, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis. Although in many agricultural environments feed particles are the major constituent of these dusts, the inflammatory responses that they provoke are likely attributable to particle-associated bacteria, archaebacteria, fungi, and viruses. In this study, we performed shotgun pyrosequencing metagenomic analyses of DNA from dusts from swine confinement facilities or grain elevators, with comparisons to dusts from pet-free households. DNA sequence alignment showed that 19% or 62% of shotgun pyrosequencing metagenomic DNA sequence reads from swine facility or household dusts, respectively, were of swine or human origin, respectively. In contrast only 2% of such reads from grain elevator dust were of mammalian origin. These metagenomic shotgun reads of mammalian origin were excluded from our analyses of agricultural dust microbiota. The ten most prevalent bacterial taxa identified in swine facility compared to grain elevator or household dust were comprised of 75%, 16%, and 42% gram-positive organisms, respectively. Four of the top five swine facility dust genera were assignable (Clostridium, Lactobacillus, Ruminococcus, and Eubacterium, ranging from 4% to 19% relative abundance). The relative abundances of these four genera were lower in dust from grain elevators or pet-free households. These analyses also highlighted the predominance in swine facility dust of Firmicutes (70%) at the phylum level, Clostridia (44%) at the Class level, and Clostridiales at the Order level (41%). In summary, shotgun pyrosequencing metagenomic analyses of agricultural dusts show that they differ qualitatively and quantitatively at the level of microbial taxa present, and that the bioinformatic analyses

Shotgun pyrosequencing metagenomic analyses of dusts from swine confinement and grain facilities.

Directory of Open Access Journals (Sweden)

Robert J Boissy

Full Text Available Inhalation of agricultural dusts causes inflammatory reactions and symptoms such as headache, fever, and malaise, which can progress to chronic airway inflammation and associated diseases, e.g. asthma, chronic bronchitis, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis. Although in many agricultural environments feed particles are the major constituent of these dusts, the inflammatory responses that they provoke are likely attributable to particle-associated bacteria, archaebacteria, fungi, and viruses. In this study, we performed shotgun pyrosequencing metagenomic analyses of DNA from dusts from swine confinement facilities or grain elevators, with comparisons to dusts from pet-free households. DNA sequence alignment showed that 19% or 62% of shotgun pyrosequencing metagenomic DNA sequence reads from swine facility or household dusts, respectively, were of swine or human origin, respectively. In contrast only 2% of such reads from grain elevator dust were of mammalian origin. These metagenomic shotgun reads of mammalian origin were excluded from our analyses of agricultural dust microbiota. The ten most prevalent bacterial taxa identified in swine facility compared to grain elevator or household dust were comprised of 75%, 16%, and 42% gram-positive organisms, respectively. Four of the top five swine facility dust genera were assignable (Clostridium, Lactobacillus, Ruminococcus, and Eubacterium, ranging from 4% to 19% relative abundance. The relative abundances of these four genera were lower in dust from grain elevators or pet-free households. These analyses also highlighted the predominance in swine facility dust of Firmicutes (70% at the phylum level, Clostridia (44% at the Class level, and Clostridiales at the Order level (41%. In summary, shotgun pyrosequencing metagenomic analyses of agricultural dusts show that they differ qualitatively and quantitatively at the level of microbial taxa present, and that the

The impact of seasonal varied human activity on characteristics and sources of heavy metals in metropolitan road dusts.

Science.gov (United States)

Men, Cong; Liu, Ruimin; Wang, Qingrui; Guo, Lijia; Shen, Zhenyao

2018-10-01

Due to significant human activity, road dust is becoming contaminated by heavy metals in many cities. To comprehensively investigate the variation of contamination level and sources of heavy metals in road dust, 10 heavy metals in road dust samples from Beijing, China, in both summer and winter, were evaluated by spatial analysis using geographic information system (GIS) mapping technology and the positive matrix factorization (PMF) Model. Although the concentrations of some heavy metals between summer and winter had similarities, the differences of others and spatial distributions of heavy metals between summer and winter were considerable. The mean concentrations of As, Cd, Cr, Cu, and Fe were lower in winter, while those of Hg, Mn, Ni, Pb, and Zn were higher. According to the values of the Pollution Index (PI) and Nemerow Integrated Pollution Index (NIPI), there were no obvious differences between summer and winter, but the range between different sites in winter was nearly twice that of summer. Based on the PMF model, four sources of heavy metals in the dust samples were identified. Although the types of sources were consistent, the relative contributions of each source differed between summer and winter. Non-exhaust vehicle emissions was the most important source in summer (34.47 wt%), while fuel combustion contributed the largest proportion to the total heavy metals in winter (32.40 wt%). The impact of each source also showed spatial variation different trends in summer and winter. With the alteration of seasons, intensity of human activities also changed, such as the number of tourists, energy needs for building temperature regulation, construction, and the amount of pesticides and fertilizer. That might be the reason for the variation of heavy metal concentrations and relative contribution of their sources between summer and winter. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of contamination for inorganic elements and phthalate esters in household dust from the metropolitan region of Sao Paulo

International Nuclear Information System (INIS)

Scapin, Valdirene de Oliveira

2009-01-01

Household dust has been identified as an important vector of exposure by inorganic and organic substances potentially toxic in children and adults. The dust composition has a strong influence of contaminants provided from internal and external environments. During the natural process of wearing or weather incidents of artifacts and materials variety, the chemical substances are released into the environment in the steam form or by leaching from final products. Once released, they can be accumulated and enriched in the dust; and by continuous exposure (inhalation, ingestion and dermal contact mechanisms), these substances are harmful to human health. In this work, a study to determine the inorganic constituents and phthalate esters concentrations in residential indoor environment dust samples, correlating them with the probable anthropogenic sources was proposed. Dust samples were collected from 69 residences in neighborhoods Pirituba, Freguesia do O, Jaragua and Perus of the Sao Paulo metropolitan region, using a domestic vacuum cleaner, between 2006 and 2008. The samples were sieved in the fractions of 850, 850-300, 300-150, 150-75, 75-63 and <63 μm. The analysis by X-ray fluorescence (WDXRF) showed the presence of Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr and Pb. The presence of phthalate esters (DEHP, DnBP, DEP, DEHA, DMP and BBP) was detected, by GCMS analyses. From the enrichment factor (EF), the elements P, S, Cr, Ni, Cu, Zn and Pb were classified as being significant and extremely enriched in the dust. The natural and anthropogenic contributions by statistical tools as factor analysis (AF) and cluster were identified. The elements Cr, Ni, Cu, Zn and Pb were present significantly elevated concentrations in relation to the total exposure values (ingestion, inhalation and skin contact) and to risk. (author)

Trace metals in fugitive dust from unsurfaced roads in the Viburnum Trend resource mining District of Missouri--implementation of a direct-suspension sampling methodology.

Science.gov (United States)

Witt, Emitt C; Wronkiewicz, David J; Pavlowsky, Robert T; Shi, Honglan

2013-09-01

Fugitive dust from 18 unsurfaced roadways in Missouri were sampled using a novel cyclonic fugitive dust collector that was designed to obtain suspended bulk samples for analysis. The samples were analyzed for trace metals, Fe and Al, particle sizes, and mineralogy to characterize the similarities and differences between roadways. Thirteen roads were located in the Viburnum Trend (VT) mining district, where there has been a history of contaminant metal loading of local soils; while the remaining five roads were located southwest of the VT district in a similar rural setting, but without any mining or industrial process that might contribute to trace metal enrichment. Comparison of these two groups shows that trace metal concentration is higher for dusts collected in the VT district. Lead is the dominant trace metal found in VT district dusts representing on average 79% of the total trace metal concentration, and was found moderately to strongly enriched relative to unsurfaced roads in the non-VT area. Fugitive road dust concentrations calculated for the VT area substantially exceed the 2008 Federal ambient air standard of 0.15μgm(-3) for Pb. The pattern of trace metal contamination in fugitive dust from VT district roads is similar to trace metal concentrations patterns observed for soils measured more than 40years ago indicating that Pb contamination in the region is persistent as a long-term soil contaminant. Published by Elsevier Ltd.

Influence of Matrix Composition on the Bioaccessibility of Copper, Zinc and Nickel in Urban Residential Dust and Soil

International Nuclear Information System (INIS)

Rasmussen, P.; Beauchemin, S.; Nugent, M.; Dugandzic, R.; Lanouette, M.; Chenier, M.

2008-01-01

This study examines factors affecting oral bioaccessibility of metals in household dust, in particular metal speciation, organic carbon content, and particle size, with the goal of addressing risk assessment information requirements. Investigation of copper (Cu) and zinc (Zn) speciation in two size fractions of dust (< 36 μ m and 80-150 μ m) using synchrotron X-ray absorption spectroscopy (XAS) indicates that the two metals are bound to different components of the dust: Cu is predominately associated with the organic phase of the dust, while Zn is predominately associated with the mineral fraction. Total and bioaccessible Cu, nickel (Ni), and Zn were determined (on dry weight basis) in the < 150 μ m size fraction of a set of archived indoor dust samples (n = 63) and corresponding garden soil samples (n = 66) from the City of Ottawa, Canada. The median bioaccessible Cu content is 66 μ g g-1 in dust compared to 5 μ g g-1 in soil; the median bioaccessible Ni content is 16 μ g g-1 in dust compared to 2 μ g g-1 in soil; and the median bioaccessible Zn content is 410 μ g g-1 in dust compared to 18 μ g g-1 in soil. For the same data set, the median total Cu content is 152 μ g g-1 in dust compared to 17 μ g g-1 in soil; the median total Ni content is 41 μ g g-1 in dust compared to 13 μ g g-1 in soil; and the median total Zn content is 626 μ g g-1 in dust compared to 84 μ g g-1 in soil. Organic carbon is elevated in indoor dust (median 28%) compared to soil (median 5%), and is a key factor controlling metal partitioning and therefore bioaccessibility. The results show that house dust and soil have distinct geochemical signatures and should not be treated as identical media in exposure and risk assessments. Separate measurements of the indoor and outdoor environment are essential to improve the accuracy of residential risk assessments.

Sustainable synthesis of metals-doped ZnO nanoparticles from zinc-bearing dust for photodegradation of phenol.

Science.gov (United States)

Wu, Zhao-Jin; Huang, Wei; Cui, Ke-Ke; Gao, Zhi-Fang; Wang, Ping

2014-08-15

A novel strategy of waste-cleaning-waste is proposed in the present work. A metals-doped ZnO (M-ZnO, M = Fe, Mg, Ca and Al) nanomaterial has been prepared from a metallurgical zinc-containing solid waste "fabric filter dust" by combining sulfolysis and co-precipitation processes, and is found to be a favorable photocatalyst for photodegradation of organic substances in wastewater under visible light irradiation. All the zinc and dopants (Fe, Mg, Ca and Al) for preparing M-ZnO are recovered from the fabric filter dust, without any addition of chemical as elemental source. The dust-derived M-ZnO samples deliver single phase indexed as the hexagonal ZnO crystal, with controllable dopants species. The photocatalytic activity of the dust-derived M-ZnO samples is characterized by photodegradation of phenol aqueous solution under visible light irradiation, giving more prominent photocatalytic behaviors than undoped ZnO. Such enhancements may be attributed to incorporation of the dust-derived metal elements (Fe, Mg, Ca and Al) into ZnO structure, which lead to the modification of band gap and refinement of grain size. The results show a feasibility to utilize the industrial waste as a resource of photodegradating organic substances in wastewater treatments. Copyright © 2014 Elsevier B.V. All rights reserved.

Dispersion and settlement of heavy metals in clay liners for sanitary landfills. Comparison of laboratory and field studies

International Nuclear Information System (INIS)

Wagner, J.F.

1992-01-01

The migration of heavy metals from long-standing waste dumps (blast furnace flue dust, ore flotation slurries, household refuse and toxic waste dumps) into natural clay barriers or artificial mineral liners was investigated in laboratory studies and field studies. (orig.) [de

Concentration Levels, Pollution Characteristics and Potential Ecological Risk of Dust Heavy Metals in the Metropolitan Area of Beijing, China.

Science.gov (United States)

Xiong, Qiulin; Zhao, Wenji; Zhao, Jiayin; Zhao, Wenhui; Jiang, Lei

2017-09-30

This study aims to investigate the concentration levels, pollution characteristics and the associated potential ecological risks of the heavy metals found in dust in the metropolitan area of Beijing, China during the winter. Dust samples were collected at 49 different spatial locations of Beijing's metropolitan area from November 2013 to January 2014, in which the concentration levels of Cd, Cr, Pb, Cu, Zn, Ni, Co, V, Bi and Mo were measured by Elan DRC II type inductively coupled plasma mass spectrometry (ICP-MS). Test results showed that the concentrations of dust heavy metals Pb, Cr, Cu and Zn in the urban areas (147.1 mg·kg -1 , 195.9 mg·kg -1 , 239.2 mg·kg -1 and 713.2 mg·kg -1 ) were significantly higher than those in the suburbs (91.6 mg·kg -1 , 125.1 mg·kg -1 , 131.9 mg·kg -1 and 514.5 mg·kg -1 ). Enrichment factors and the geo-accumulation index were used to describe the pollution characteristics of dust heavy metals in urban and suburban areas. Results indicated that Zn and Cu were moderately polluting in both urban and suburban areas, Cd was severely polluting in urban areas and heavily polluting in the suburbs. Furthermore, potential ecological risk assessment revealed that the degrees of ecological harm of dust heavy metals were very strong in both urban and suburban areas, but especially in urban areas. The potential ecological risk of heavy metal Cd, whose single factor of ecological damage was extremely strong, accounted for about 90% of the total ecological risk.

Heavy metal speciation in various grain sizes of industrially contaminated street dust using multivariate statistical analysis.

Science.gov (United States)

Yıldırım, Gülşen; Tokalıoğlu, Şerife

2016-02-01

A total of 36 street dust samples were collected from the streets of the Organised Industrial District in Kayseri, Turkey. This region includes a total of 818 work places in various industrial areas. The modified BCR (the European Community Bureau of Reference) sequential extraction procedure was applied to evaluate the mobility and bioavailability of trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in street dusts of the study area. The BCR was classified into three steps: water/acid soluble fraction, reducible and oxidisable fraction. The remaining residue was dissolved by using aqua regia. The concentrations of the metals in street dust samples were determined by flame atomic absorption spectrometry. Also the effect of the different grain sizes (dust samples on the mobility of the metals was investigated using the modified BCR procedure. The mobility sequence based on the sum of the first three phases (for grain size) was: Cd (71.3)>Cu (48.9)>Pb (42.8)=Cr (42.1)>Ni (41.4)>Zn (40.9)>Co (36.6)=Mn (36.3)>Fe (3.1). No significant difference was observed among metal partitioning for the three particle sizes. Correlation, principal component and cluster analysis were applied to identify probable natural and anthropogenic sources in the region. The principal component analysis results showed that this industrial district was influenced by traffic, industrial activities, air-borne emissions and natural sources. The accuracy of the results was checked by analysis of both the BCR-701 certified reference material and by recovery studies in street dust samples. Copyright © 2015 Elsevier Inc. All rights reserved.

Spatial distribution and contamination assessment of heavy metals in street dust from Camagüey city (Cuba) using X-ray fluorescence

International Nuclear Information System (INIS)

Rizo, Oscar Díaz; Rivero Palma, Orestes; D’Alessandro Rodríguez, Katia; García Trápaga, César

2015-01-01

Concentrations of Cr, Co, Ni, Cu, Zn, Pb and Fe in the street dust from Camagüey city were studied by X-ray fluorescence analysis. The mean Cr, Co, Ni, Cu, Zn and Pb contents in the urban dust samples (97 ± 30, 14 ± 2, 35 ± 36, 94 ± 26, 199 ± 87 and 42 ± 29 mg.kg-1 dry weight, respectively) were compared with mean concentrations for other cities around the world. Spatial distribution maps indicated the same behaviour for Cr–Ni and Pb–Zn–Cu, respectively, whereas the spatial distribution of Co differs from other heavy metals. The metal-to-iron normalization, using Cuban average metal soil contents as background, showed that street dusts from Camagüey city are moderately or significantly Zn-Pb enriched in those areas associated with heavy traffic density and metallurgic plant location. However, the calculation of the potential ecological risk index shows that metal content in Camagüey street dust go not represent any risk for city population. (author)

Heavy metals characteristics of settled particles of streets dust from Diwaniyah City- Qadisiyah Governorate - Southern Iraq

Science.gov (United States)

Al-Dabbas, Moutaz A.; Mahdi, Khalid H.; Al-Khafaji, Raad; Obayes, Kawthar H.

2018-05-01

Road-side dust samples were collected from selected areas of Diwaniyah city-Qadisiyah Governorate - Southern Iraq. The heavy metals (Fe, Co, Ni, Cu, Zn and Pb) in these streets dust samples were studied and used as indicator for pollution by using three of main indices (I-geo, CF, and PLI). Determination of heavy metal in the roadside dust is with XRD and XRF methods. I-geo for Co, Zn, Pb, and Ni in the studied sites shows relative values of class 1, which indicated the slightly polluted, while I-geo for Fe and Cu shows relative values of class 0, which indicated no pollution. The contamination factor for Co, Zn, Pb, and Ni classified as class 2, which indicate moderately contamination, while the contamination factor for Fe and Cu classified as class 1, which indicate low contamination. PLI values in the all of studied sites classified as class 2 (Deterioration on site quality) indicating local pollution, as well as denote perfection with (class 0) of no pollution. The distribution pattern of metals percentages was affected by gases emitted from transportation vehicles as well as the prevailing wind direction.

Sustainable synthesis of metals-doped ZnO nanoparticles from zinc-bearing dust for photodegradation of phenol

International Nuclear Information System (INIS)

Wu, Zhao-Jin; Huang, Wei; Cui, Ke-Ke; Gao, Zhi-Fang; Wang, Ping

2014-01-01

Highlights: • Multi-doped ZnO (M-ZnO) was prepared from Zn-bearing dust for waste-cleaning-waste. • All the dopants M (Fe, Mg, Ca and Al) and Zn are recovered from the dust. • Doping by the dust-derived M expands excitability of ZnO to visible light region. • M-ZnO has good catalytic activity in the degradation of phenol under visible light. - Abstract: A novel strategy of waste-cleaning-waste is proposed in the present work. A metals-doped ZnO (M-ZnO, M = Fe, Mg, Ca and Al) nanomaterial has been prepared from a metallurgical zinc-containing solid waste “fabric filter dust” by combining sulfolysis and co-precipitation processes, and is found to be a favorable photocatalyst for photodegradation of organic substances in wastewater under visible light irradiation. All the zinc and dopants (Fe, Mg, Ca and Al) for preparing M-ZnO are recovered from the fabric filter dust, without any addition of chemical as elemental source. The dust-derived M-ZnO samples deliver single phase indexed as the hexagonal ZnO crystal, with controllable dopants species. The photocatalytic activity of the dust-derived M-ZnO samples is characterized by photodegradation of phenol aqueous solution under visible light irradiation, giving more prominent photocatalytic behaviors than undoped ZnO. Such enhancements may be attributed to incorporation of the dust-derived metal elements (Fe, Mg, Ca and Al) into ZnO structure, which lead to the modification of band gap and refinement of grain size. The results show a feasibility to utilize the industrial waste as a resource of photodegradating organic substances in wastewater treatments

Inactivation of dust mites, dust mite allergen, and mold from carpet.

Science.gov (United States)

Ong, Kee-Hean; Lewis, Roger D; Dixit, Anupma; MacDonald, Maureen; Yang, Mingan; Qian, Zhengmin

2014-01-01

Carpet is known to be a reservoir for biological contaminants, such as dust mites, dust mite allergen, and mold, if it is not kept clean. The accumulation of these contaminants in carpet might trigger allergies or asthma symptoms in both children and adults. The purpose of this study is to compare methods for removal of dust mites, dust mite allergens, and mold from carpet. Carpets were artificially worn to simulate 1 to 2 years of wear in a four-person household. The worn carpets were inoculated together with a common indoor mold (Cladosporium species) and house dust mites and incubated for 6 weeks to allow time for dust mite growth on the carpet. The carpets were randomly assigned to one of the four treatment groups. Available treatment regimens for controlling carpet contaminants were evaluated through a literature review and experimentation. Four moderately low-hazard, nondestructive methods were selected as treatments: vacuuming, steam-vapor, Neem oil (a natural tree extract), and benzalkonium chloride (a quaternary ammonium compound). Steam vapor treatment demonstrated the greatest dust mite population reduction (p 0.05) for both physical and chemical methods. The steam-vapor treatment effectively killed dust mites and denatured dust mite allergen in the laboratory environment.

Dust Abundance Variations in the Magellanic Clouds: Probing the Life-cycle of Metals with All-sky Surveys

Science.gov (United States)

Roman-Duval, Julia; Bot, Caroline; Chastenet, Jeremy; Gordon, Karl

2017-06-01

Observations and modeling suggest that dust abundance (gas-to-dust ratio, G/D) depends on (surface) density. Variations of the G/D provide timescale constraints for the different processes involved in the life cycle of metals in galaxies. Recent G/D measurements based on Herschel data suggest a factor of 5-10 decrease in dust abundance between the dense and diffuse interstellar media (ISM) in the Magellanic Clouds. However, the relative nature of the Herschel measurements precludes definitive conclusions as to the magnitude of those variations. We investigate variations of the dust abundance in the LMC and SMC using all-sky far-infrared surveys, which do not suffer from the limitations of Herschel on their zero-point calibration. We stack the dust spectral energy distribution (SED) at 100, 350, 550, and 850 microns from IRAS and Planck in intervals of gas surface density, model the stacked SEDs to derive the dust surface density, and constrain the relation between G/D and gas surface density in the range 10-100 M ⊙ pc-2 on ˜80 pc scales. We find that G/D decreases by factors of 3 (from 1500 to 500) in the LMC and 7 (from 1.5× {10}4 to 2000) in the SMC between the diffuse and dense ISM. The surface-density-dependence of G/D is consistent with elemental depletions, and with simple modeling of the accretion of gas-phase metals onto dust grains. This result has important implications for the sub-grid modeling of galaxy evolution, and for the calibration of dust-based gas-mass estimates, both locally and at high redshift.

Sequential heavy metal extraction from dust precipitates and road sediments. Part 2. Sequential heavy metal extraction from urban dust; Sequentielle Schwermetallextraktion aus Staubniederschlaegen und Strassensedimenten. T. 2. Sequentielle Schwermetallextraktion von staedtischen Staeuben

Energy Technology Data Exchange (ETDEWEB)

Heiser, U.; Norra, S.; Stueben, D.; Wagner, M. von [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Petrographie und Geochemie

1999-03-01

For the application of our method for the sequential extraction of heavy metals from microsamples presented in part 1 (`Sequentielle Schwermetallextraktion von Mikroproben` - `Sequential Extraction of Heavy Metals from Micro Samples`) an investigation was carried out to evaluate airborne dust fallout and street sediments at two urban sites where different heavy metal immission rates occur due to traffic influence. In the street sediments the total concentrations of zinc, copper and lead was three to fivefold higher in the silt and clay fraction (<63 {mu}m) than in the particle size fraction (<1,12 mm), but showed nearly the same mobilisation behaviour. The dust samples showed equal mobilisation behaviour as the street sediments for copper and lead, while zinc was considerably more mobile in the dust samples: In extraction steps I-IV (I: mobile fraction; II: easily deliverable fraction; III: fraction bound to manganese oxides; IV: fraction bound organic to matter) zinc, copper and lead in street sediments, as well as copper and lead in dust samples, were dissolved to 40-70%, whereas about 80% of zinc in the dust samples was already dissolved in extraction step I. (orig.) [Deutsch] Mit Hilfe des in Teil 1 (`Sequentielle Schwermetallextraktion von Mikroproben`) vorgestellten Verfahrens zur sequentiellen Schwermetallextraktion von Mikroproben wurden die Mobilisierbarkeiten von Zink, Kupfer und Blei aus Staubniederschlaegen und aus der Schluff- und Tonfraktion von Strassensedimenten an zwei urbanen Standorten mit unterschiedlicher, verkehrsbedingter Schwermetallbelastung untersucht und miteinander verglichen. In Strassensedimenten wiesen Zink, Kupfer und Blei in der Schluff- und Tonfraktion drei- bis fuenffach hoehere Gesamtgehalte auf als die Korngroessenfraktion <1,12 mm, zeigten aber aehnliches Verhalten in der Mobilisierbarkeit. Bei den Staubproben war die Mobilisierbarkeit von Kupfer und Blei aehnlich wie in den Strassensedimenten, waehrend sich Zink als erheblich

Evaluation of the concentration of allergens from mites in fur and households dust of dogs with atopic dermatitis

Directory of Open Access Journals (Sweden)

Dévaki L. de Assunção

Full Text Available ABSTRACT: This study evaluated the concentration of Der p 1, Der f 1 and Blo t 5 in the fur and households of 20 dogs with atopic dermatitis (AD and 20 healthy dogs. The diagnosis of AD was clinical based on Favrot’s criteria. Dust samples were collected with a domestic vacuum cleaner. For each site, 1m2 was vacuumed for 2 min. The samples were collected in separate filters, transferred into plastic containers, sealed and kept frozen until ELISA analysis. In the fur of atopic dogs the average concentration of Der p 1 was 0.25μg/g compared to 0.03μg/g in healthy dogs. In households with atopic dogs the highest concentrations of Der p 1 were found in carpets (2.18μg/g, followed by couches (1.53μg/g, beds (1.14μg/g, dogs’ bed linen (0.64μg/g and floors (0.14μg/g. The concentrations of Der p 1 on carpets, couches and beds were significantly higher than in atopic dogs’ fur (p0.05. The concentrations of Der p 1, Der f 1 and Blo t 5 were equivalent in atopic and non-atopic dog’s households. Among the allergens studied, Der p 1 was the most commonly found, predominantly in carpets and couches.

Inhalable desert dust, urban emissions, and potentially biotoxic metals in urban Saharan-Sahelian air

Science.gov (United States)

Garrison, Virginia H.; Majewski, Michael S.; Konde, Lassana; Wolf, Ruth E.; Otto, Richard D.; Tsuneoka, Yutaka

2014-01-01

Saharan dust incursions and particulates emitted from human activities degrade air quality throughout West Africa, especially in the rapidly expanding urban centers in the region. Particulate matter (PM) that can be inhaled is strongly associated with increased incidence of and mortality from cardiovascular and respiratory diseases and cancer. Air samples collected in the capital of a Saharan–Sahelian country (Bamako, Mali) between September 2012 and July 2013 were found to contain inhalable PM concentrations that exceeded World Health Organization (WHO) and US Environmental Protection Agency (USEPA) PM2.5 and PM10 24-h limits 58 – 98% of days and European Union (EU) PM10 24-h limit 98% of days. Mean concentrations were 1.2-to-4.5 fold greater than existing limits. Inhalable PM was enriched in transition metals, known to produce reactive oxygen species and initiate the inflammatory response, and other potentially bioactive and biotoxic metals/metalloids. Eroded mineral dust composed the bulk of inhalable PM, whereas most enriched metals/metalloids were likely emitted from oil combustion, biomass burning, refuse incineration, vehicle traffic, and mining activities. Human exposure to inhalable PM and associated metals/metalloids over 24-h was estimated. The findings indicate that inhalable PM in the Sahara–Sahel region may present a threat to human health, especially in urban areas with greater inhalable PM and transition metal exposure.

Chemical speciation and human health risk of trace metals in urban street dusts from a metropolitan city, Nanjing, SE China

Energy Technology Data Exchange (ETDEWEB)

Li, Huiming; Qian, Xin, E-mail: xqian@nju.edu.cn; Hu, Wei; Wang, Yulei; Gao, Hailong

2013-07-01

The modified BCR (the European Community Bureau of Reference) sequential extraction procedure was applied for partitioning and evaluating the mobility, availability and persistence of trace metals (Al, Cd, Co, Cr, Cu, Ni, Pb, Sr, V and Zn) in urban street dusts collected from different areas of Nanjing, China. The mobility sequence based on the sum of the BCR sequential extraction stages was: Sr (91.65%) > Pb (79.16%) > Zn (74.26%) > Cu (68.53%) > Co (45.98%) > Al (40.01%) ≈ V (38.45%) ≈ Ni (37.88%) > Cr (29.35%) > Cd (22.68%). Almost every trace metal had its highest total concentrations in the industrial area, except for Sr which had its highest concentration in the commercial area. Contamination factors (Cf), risk assessment code (RAC) and enrichment factor (Ef) were then calculated to further assess the environmental risk and provide a preliminary estimate of the main sources of trace metals in street dusts. Non-carcinogenic effects and carcinogenic effects due to exposure to urban street dusts were assessed for both children and adults. For non-carcinogenic effects, ingestion was the main route of exposure to street dusts for these metals, followed by dermal contact and inhalation. Hazard index values for all studied metals were lower than the safe level of 1, and Pb exhibited the highest risk value (0.125) in the case of children. The carcinogenic risk for Cd, Co, Cr and Ni were all below the acceptable level (< 10{sup −6}). - Highlights: • This study assesses a comprehensive environmental risk of urban trace metal pollution. • This study evaluates human health risk combined with the speciation of trace metals. • This study points the critical contaminated metals that need to be paid special attention. • This study supplies useful information and reference on the application of BCR SPE method.

A comparative study of health risk of potentially toxic metals in urban and suburban road dust in the most populated city of China

Science.gov (United States)

Shi, Guitao; Chen, Zhenlou; Bi, Chunjuan; Wang, Li; Teng, Jiyan; Li, Yuansheng; Xu, Shiyuan

2011-01-01

Urban and suburban road dust samples were collected in the most populated city of China, Shanghai. Size fractions of dust particles were analyzed; metal levels of the dust were also measured. Human exposure to individual toxic metals through road dust was assessed for both children and adults. The results showed that dust particles from urban and suburban road were presented similar size distribution pattern, with most particles in the range of 100-400 μm. Urban road dust consisted of higher proportions of inhalable, thoracic and respirable particles with increased risk of adverse effects to human. In general, mean grain sizes of urban road dust were smaller than suburban dust. Total organic carbon contents and levels of Pb, Cd, Cu, Zn, Ni, Cr in urban dust were higher than those of suburban dust. But the concentrations of As and Hg from suburban dust were higher, indicting a different main source. The exposure pathway which resulted in the highest level of risk for human exposed to road dust was ingestion of this material, which was followed by dermal contact. Except for some locations, risk values of both cancer and non-cancer obtained in this study were in the receivable range on the whole. Children had greater health risks than adults. The overall risks of non-cancer in urban area were higher than those in suburban area, but the values of cancer in the two areas were comparable. As for the aggregate noncarcinogenic risk, Pb was of most concern regarding the potential occurrence of health impacts. Of the three carcinogenic metals As, Cr and Cd, the only mean risk higher than 10 -6 was Cr, accounting for a great percentage (95%) of the overall risk of cancer. Hence, potentially adverse health effects arising from Pb and Cr in road dust should arouse wide concern.

Dust and molecules in extra-galactic planetary nebulae

Science.gov (United States)

Garcia-Hernandez, Domingo Aníbal

2015-08-01

Extra-galactic planetary nebulae (PNe) permit the study of dust and molecules in metallicity environments other than the Galaxy. Their known distances lower the number of free parameters in the observations vs. models comparison, providing strong constraints on the gas-phase and solid-state astrochemistry models. Observations of PNe in the Galaxy and other Local Group galaxies such as the Magellanic Clouds (MC) provide evidence that metallicity affects the production of dust as well as the formation of complex organic molecules and inorganic solid-state compounds in their circumstellar envelopes. In particular, the lower metallicity MC environments seem to be less favorable to dust production and the frequency of carbonaceous dust features and complex fullerene molecules is generally higher with decreasing metallicity. Here, I present an observational review of the dust and molecular content in extra-galactic PNe as compared to their higher metallicity Galactic counterparts. A special attention is given to the level of dust processing and the formation of complex organic molecules (e.g., polycyclic aromatic hydrocarbons, fullerenes, and graphene precursors) depending on metallicity.

Bioaccessibility of Fipronil Sorbed to Soil and House Dust

Science.gov (United States)

Fipronil is a phenylpyrazole insecticide with uses ranging from soil treatment, to the control of household pests and ectoparasites on pets. Soils and house dusts readily sorb fipronil and when these soils and dusts are ingested, the fipronil may become bioaccessible for uptake ...

Group 1 and 2 Dermatophagoides house dust mite allergens in the microenvironment of cats.

Science.gov (United States)

Loft, Klaus Earl; Rosser, Edmund J

2010-04-01

House dust mite allergens (HDMAs) are some of the most common allergens associated with allergic diseases in humans and dogs. The purpose of this study was to determine whether HDMAs could be detected in cat-associated household microenvironments. From 50 cat-only households with 95 cats, dust samples were collected by vacuuming for 2 min m(-2) from three areas where cats slept or rested regularly from September to October 2006. Relative humidity and temperature were measured in each household using a data logger. Each owner completed a questionnaire on potential factors that might influence the prevalence of house dust mites (HDMs). Dust samples were analysed utilizing an ELISA for Der p 1, Der f 1 and HDM group 2 allergens. In 38 of 50 households there was greater than 2 microg g(-1) of dust for at least one HDMA. Using stepwise logistic regression, factors associated with increased HDMA levels included: free-standing houses, number of humans in household, longhaired cats and age of the cat. Factors associated with decreased HDMA concentrations included: forced air heating and central air conditioning, less than 50% carpeting of the home, use of flea control, cats suffering from dermatological disease and the average temperature of the household. Many sleeping/resting areas utilized by cats contain sufficiently high levels of HDMAs to be potential sources of sensitization. This finding should lead to further determination of the role of HDMs in cats suffering from putative allergic conditions such as atopic dermatitis or asthma.

Air-conditioner filters enriching dust mites allergen.

Science.gov (United States)

Zhan, Xiaodong; Li, Chaopin; Xu, Haifeng; Xu, Pengfei; Zhu, Haibin; Diao, Jidong; Li, Na; Zhao, Beibei

2015-01-01

We detected the concentration of dust mites allergen (Der f1 & Der p1) in the air of different places before and after the starting of air-conditioners in Wuhu City, Anhui, China, and to discuss the relation between the dust mites allergen in air-conditioner filters and the asthma attack. The dust samples were collected from the air-conditioner filters in dining rooms, shopping malls, hotels and households respectively. Concentrations of dust mites major group allergen 1 (Der f 1, Der p1) were detected with enzyme linked immunosorbent assay (ELISA), and the dust mite immune activities were determined by dot-ELISA. The concentration of Der f1 in dining rooms, shopping malls, hotels and households was 1.52 μg/g, 1.24 μg/g, 1.31 μg/g and 1.46 μg/g respectively, and the concentration of Der p1 in above-mentioned places was 1.23 μg/g, 1.12 μg/g, 1.16 μg/g and 1.18 μg/g respectively. The concentration of Der f1 & Der p1 in air was higher after the air-conditioners starting one hours later, and the difference was significant (Pair-conditioner filters can enrich dust mites major group allergen, and the allergens can induce asthma. The air-conditioner filters shall be cleaned or replaced regularly to prevent or reduce accumulation of the dust mites and its allergens.

The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust

Energy Technology Data Exchange (ETDEWEB)

Zhang, Haibo, E-mail: hbzhang@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Luo, Yongming, E-mail: ymluo@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Makino, Tomoyuki [National Institute for Agro-Environmental Sciences, Tsukuba 3058604 (Japan); Wu, Longhua [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Nanzyo, Masami [Tohoku University, Sendai 9808576 (Japan)

2013-03-15

Highlights: ► A continuous flow ultra-centrifugation method has been developed to obtain fine particles from polluted agricultural soil. ► Pollution source affected the heavy metal fractionation in size-fractions by changing soil particle properties. ► The iron oxides affected the distribution of lead species more than other metals in the smelter dust polluted particles. -- Abstract: The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessblity of the metals as well as the mobility of the fine particles in soil.

The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust

International Nuclear Information System (INIS)

Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami

2013-01-01

Highlights: ► A continuous flow ultra-centrifugation method has been developed to obtain fine particles from polluted agricultural soil. ► Pollution source affected the heavy metal fractionation in size-fractions by changing soil particle properties. ► The iron oxides affected the distribution of lead species more than other metals in the smelter dust polluted particles. -- Abstract: The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessblity of the metals as well as the mobility of the fine particles in soil

Leachability of Cr(VI) and other metals from asphalt composites with addition of filter dust.

Science.gov (United States)

Vahcic, Mitja; Milacic, Radmila; Mladenovic, Ana; Murko, Simona; Zuliani, Tea; Zupancic, Marija; Scancar, Janez

2008-12-01

The potential use of filter dust in asphalt composites for road construction was investigated. Filter dust contains high concentrations of metals, of which Cr(VI) and Pb are leached with water. Compact and ground asphalt composites with addition of 2% of filter dust by mass were studied. In order to evaluate their environmental impact, leachability tests were performed using water and salt water as leaching agents. The concentrations of Cr(VI) and Pb were determined in leachates over a time period of 182 days. The results indicated that Pb was not leached with leaching agents from asphalt composites. Cr(VI) was also not leached with leaching agents from compact asphalt composites. However, in ground asphalt composites, Cr(VI) was leached with water in concentrations up to 220 microg L(-1) and in salt water up to 150 microg L(-1). From the physico-mechanical and environmental aspects, filter dust can be used as a component in asphalt mixtures.

Fractionation And Distribution Of Heavy Metals In street Dust In Amman, Jordan

International Nuclear Information System (INIS)

Jaradat, Q.

2002-01-01

Different types of street dust: major streets, minor streets, gas stations, traffic lights and car parks in Amman were subjected to size-fractionation into three sizes: 500-125μm , 125-53μm, and <53μm. Sequential extraction was also performed on the non-fractionated samples using Tessier procedure. The sequentially extracted and the fractionated samples were analyzed for Pb, Cd, Zn and Mn using flame atomic absorption. The silt fraction ( <53μm particles ) contains the highest concentrations of all elements in most types of street dust samples followed by the fine fraction ( 125-53μm particles). From the sequential extraction data, the highest concentrations of heavy metals were : Pb, Cd, Zn and in Fe-Mn oxide fraction, and Cu in the organic fraction. (author). 29 refs., 2 figs., 4 tabs

Saharan dust - a carrier of persistent organic pollutants, metals and microbes to the Caribbean?

Directory of Open Access Journals (Sweden)

V.H Garrison

2006-12-01

Full Text Available An international team of scientists from government agencies and universities in the United States, U.S. Virgin Islands (USVI, Trinidad & Tobago, the Republic of Cape Verde, and the Republic of Mali (West Africa is working together to elucidate the role Saharan dust may play in the degradation of Caribbean ecosystems. The first step has been to identify and quantify the persistent organic pollutants (POPs, trace metals, and viable microorganisms in the atmosphere in dust source areas of West Africa, and in dust episodes at downwind sites in the eastern Atlantic (Cape Verde and the Caribbean (USVI and Trinidad & Tobago. Preliminary findings show that air samples from Mali contain a greater number of pesticides, polychlorinated biphenyls (PCBs and polycyclic aromatic hydrocarbons (PAHs and in higher concentrations than the Caribbean sites. Overall, POP concentrations were similar in USVI and Trinidad samples. Trace metal concentrations were found to be similar to crustal composition with slight enrichment of lead in Mali. To date, hundreds of cultureable micro-organisms have been identified from Mali, Cape Verde, USVI, and Trinidad air samples. The sea fan pathogen, Aspergillus sydowii, has been identified in soil from Mali and in air samples from dust events in the Caribbean. We have shown that air samples from a dust-source region contain orders of magnitude more cultureable micro-organisms per volume than air samples from dust events in the Caribbean, which in turn contain 3-to 4-fold more cultureable microbes than during non-dust conditions. Rev. Biol. Trop. 54 (Suppl. 3: 9-21. Epub 2007 Jan. 15.Un grupo internacional de agencias gubernamentales y universidades de los Estados Unidos, las Islas Vírgenes (EUA, Trinidad y Tobago, la República de Cabo Verde y la República de Mali (África Oeste, está trabajando en conjunto para elucidar el papel que el polvo del Sahara puede estar jugando en el deterioro de los ecosistemas caribeños. El

Does the source migration pathway of HBCDs to household dust influence their bio-accessibility?

Energy Technology Data Exchange (ETDEWEB)

García-Alcega, Sonia [Soil Research Centre, University of Reading, Reading RG6 6AH (United Kingdom); Rauert, Cassie; Harrad, Stuart [School of Geography Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT (United Kingdom); Collins, Chris D., E-mail: c.d.collins@reading.ac.uk [Soil Research Centre, University of Reading, Reading RG6 6AH (United Kingdom)

2016-11-01

A study was conducted to assess the human bioaccessibility of dust contaminated with hexabromocyclododecane (HBCD) via two migration pathways a) volatilisation with subsequent partitioning to dust particles, and b) abrasion of treated textile fibres directly to the dust. This was achieved using previously developed experimental chamber designs to generate dust samples contaminated with HBCDs emitted from a HBCD treated textile curtain. The generated dust samples were exposed to an in vitro colon extended physiologically based extraction test (CE-PBET). The bioaccessibility of the HBCDs which were incorporated within dust as a result of volatilisation from the curtain material with subsequent partitioning to dust was higher than in dusts contaminated with HBCDs via abrasion of the curtain (35% and 15% respectively). We propose this occurs due to a stronger binding of HBCDs to treated fabric fibres than that experienced following volatilisation and sorption of HBCDs to dust particles. - Highlights: • Migration pathways via which HBCDs enter dust influences its bioaccessibility. • HBCDs more bioaccessible when incorporated to dust via volatilisation. • Contamination of dusts is more variable via abrasion than volatilisation.

Does the source migration pathway of HBCDs to household dust influence their bio-accessibility?

International Nuclear Information System (INIS)

García-Alcega, Sonia; Rauert, Cassie; Harrad, Stuart; Collins, Chris D.

2016-01-01

A study was conducted to assess the human bioaccessibility of dust contaminated with hexabromocyclododecane (HBCD) via two migration pathways a) volatilisation with subsequent partitioning to dust particles, and b) abrasion of treated textile fibres directly to the dust. This was achieved using previously developed experimental chamber designs to generate dust samples contaminated with HBCDs emitted from a HBCD treated textile curtain. The generated dust samples were exposed to an in vitro colon extended physiologically based extraction test (CE-PBET). The bioaccessibility of the HBCDs which were incorporated within dust as a result of volatilisation from the curtain material with subsequent partitioning to dust was higher than in dusts contaminated with HBCDs via abrasion of the curtain (35% and 15% respectively). We propose this occurs due to a stronger binding of HBCDs to treated fabric fibres than that experienced following volatilisation and sorption of HBCDs to dust particles. - Highlights: • Migration pathways via which HBCDs enter dust influences its bioaccessibility. • HBCDs more bioaccessible when incorporated to dust via volatilisation. • Contamination of dusts is more variable via abrasion than volatilisation.

An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-redshift AGB Analogs

Science.gov (United States)

Boyer, M. L.; McQuinn, K. B. W.; Groenewegen, M. A. T.; Zijlstra, A. A.; Whitelock, P. A.; van Loon, J. Th.; Sonneborn, G.; Sloan, G. C.; Skillman, E. D.; Meixner, M.; McDonald, I.; Jones, O. C.; Javadi, A.; Gehrz, R. D.; Britavskiy, N.; Bonanos, A. Z.

2017-12-01

The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) identified several candidate Asymptotic Giant Branch (AGB) stars in nearby dwarf galaxies and showed that dust can form even in very metal-poor systems ({\\boldsymbol{Z}}∼ 0.008 {Z}ȯ ). Here, we present a follow-up survey with WFC3/IR on the Hubble Space Telescope (HST), using filters that are capable of distinguishing carbon-rich (C-type) stars from oxygen-rich (M-type) stars: F127M, F139M, and F153M. We include six star-forming DUSTiNGS galaxies (NGC 147, IC 10, Pegasus dIrr, Sextans B, Sextans A, and Sag DIG), all more metal-poor than the Magellanic Clouds and spanning 1 dex in metallicity. We double the number of dusty AGB stars known in these galaxies and find that most are carbon rich. We also find 26 dusty M-type stars, mostly in IC 10. Given the large dust excess and tight spatial distribution of these M-type stars, they are most likely on the upper end of the AGB mass range (stars undergoing Hot Bottom Burning). Theoretical models do not predict significant dust production in metal-poor M-type stars, but we see evidence for dust excess around M-type stars even in the most metal-poor galaxies in our sample (12+{log}({{O}}/{{H}})=7.26{--}7.50). The low metallicities and inferred high stellar masses (up to ∼10 {M}ȯ ) suggest that AGB stars can produce dust very early in the evolution of galaxies (∼30 Myr after they form), and may contribute significantly to the dust reservoirs seen in high-redshift galaxies. Based on observations made with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-14073.

Endotoxin, Coliform, and Dust Levels in Various Types of Rodent Bedding

OpenAIRE

Whiteside, Tanya E; Thigpen, Julius E; Kissling, Grace E; Grant, Mary G; Forsythe, Diane B

2010-01-01

Endotoxins in grain dust, household dust, and animal bedding may induce respiratory symptoms in rodents and humans. We assayed the endotoxin, coliform, and dust levels in 20 types of rodent bedding. Endotoxin concentrations were measured by using a commercial test kit, coliform counts were determined by using conventional microbiologic procedures, and dust content was evaluated by using a rotating–tapping shaker. Paper bedding types contained significantly less endotoxin than did other beddin...

Polybrominated diphenyl ethers (PBDEs) and heavy metals in road dusts from a plastic waste recycling area in north China: implications for human health.

Science.gov (United States)

Tang, Zhenwu; Huang, Qifei; Yang, Yufei; Nie, Zhiqiang; Cheng, Jiali; Yang, Jun; Wang, Yuwen; Chai, Miao

2016-01-01

Road dusts were collected from an area where intense mechanical recycling of plastic wastes occurs in Wen'an, north China. These dusts were investigated for polybrominated diphenyl ethers (PBDEs) and heavy metals contamination to assess the health risk related to these components. Decabromodiphenyl ether (BDE-209) and Σ21PBDE concentrations in these dusts ranged from 2.67 to 10,424 ng g(-1) and from 3.23 to 10,640 ng g(-1), respectively. These PBDE concentrations were comparable to those observed in road dust from e-waste recycling areas but were 1-2 orders of magnitude higher than concentrations in outdoor or road dusts from other areas. This indicates that road dusts in the study area have high levels of PBDE pollution. BDE-209 was the predominant congener, accounting for 86.3% of the total PBDE content in dusts. Thus, commercial deca-BDE products were the dominant source. The average concentrations of As, Cd, Cr, Cu, Hg, Pb, Sb, and Zn in these same dust samples were 10.1, 0.495, 112, 54.7, 0.150, 71.8, 10.6, and 186 mg kg(-1), respectively. The geoaccumulation index suggests that road dusts in this area are moderately to heavily polluted with Cd, Hg, and Sb. This study shows that plastic waste processing is a major source of toxic pollutants in road dusts in this area. Although the health risk from exposure to dust PBDEs was low, levels of some heavy metals in this dust exceeded acceptable risk levels for children and are of great concern.

Pollution characteristics and health risk assessment of heavy metals in street dusts from different functional areas in Beijing, China.

Science.gov (United States)

Wei, Xin; Gao, Bo; Wang, Peng; Zhou, Huaidong; Lu, Jin

2015-02-01

Street dusts from Heavy Density Traffic Area, Residential Area, Educational Area and Tourism Area in Beijing, China, were collected to study the distribution, accumulation and health risk assessment of heavy metals. Cr, Cu, Zn, Cd and Pb concentrations were in higher concentrations in these four locations than in the local soil background. In comparison with the concentrations of selected metals in other cities, the concentrations of heavy metals in Beijing were generally at moderate or low levels. Ni, Cu, Zn and Pb concentrations in the Tourism Area were the highest among four different areas in Beijing. A pollution assessment by Geoaccumulation Index showed that the pollution level for the heavy metals is in the following order: Cd>Pb>Zn>Cu>Cr>Ni. The Cd levels can be considered "heavily contaminated" status. The health risk assessment model that was employed to calculate human exposure indicated that both non-carcinogenic and carcinogenic risks of selected metals in street dusts were generally in the low range, except for the carcinogenic risk from Cr for children. Copyright © 2014 Elsevier Inc. All rights reserved.

Content of Heavy Metal in the Dust of Leisure Squares and Its Health Risk Assessment-A Case Study of Yanta District in Xi'an.

Science.gov (United States)

Shao, Tianjie; Pan, Lihuan; Chen, Zhiqing; Wang, Ruiyuan; Li, Wenjing; Qin, Qing; He, Yuran

2018-02-25

Taking Yanta District in Xi'an as the research object, the present study measures the contents of Cadmium (Cd), Lead (Pb), Copper (Cu), Nickel (Ni), and Chromium (Cr) in dust samples and further assesses the health risk of heavy metals intake through dust based on the assessment method of human exposure risk proposed by U.S. EPA, with an aim to investigate the content of heavy metal in the dust of leisure squares and its exposure risk. As the results indicate, the average contents of five heavy metals are obviously higher than the soil background value in Shaanxi Province. Therefore, Cd, Ni, Cu, Pb, and Cr are obviously enriched in urban surface dust in Shaanxi Province, due to the influence of human activities. In addition, it can also be found that the non-carcinogen exposure risk in children is significantly higher than that in adults with the risk values of these five heavy metals all one order of magnitude higher than those of adults. Irrespective of whether addressing the results for children or adults, the non-carcinogen exposure doses of five heavy metals are sorted as Cr > Pb > Cu > Ni > Cd. According to the present situation, for a child, the total non-carcinogenic risk values of five heavy metals have exceeded the safety limit in 11 of the 20 leisure squares in Yanta District of Xi'an. That means the leisure squares are no longer suitable for physical and recreational activities. For the five heavy metals, the average non-carcinogenic risk value of Cr is largest, and causes the largest threat to health in Yanta District, Xi'an. The carcinogenic exposure doses of the heavy metals Cr, Cd, and Ni are very low in respiratory pathways and there is no carcinogenic health risk. In general, the Cr content in dust in domestic cities is higher than that of foreign cities; however, the Pb content is much lower.

Content of Heavy Metal in the Dust of Leisure Squares and Its Health Risk Assessment—A Case Study of Yanta District in Xi’an

Directory of Open Access Journals (Sweden)

Tianjie Shao

2018-02-01

Full Text Available Taking Yanta District in Xi’an as the research object, the present study measures the contents of Cadmium (Cd, Lead (Pb, Copper (Cu, Nickel (Ni, and Chromium (Cr in dust samples and further assesses the health risk of heavy metals intake through dust based on the assessment method of human exposure risk proposed by U.S. EPA, with an aim to investigate the content of heavy metal in the dust of leisure squares and its exposure risk. As the results indicate, the average contents of five heavy metals are obviously higher than the soil background value in Shaanxi Province. Therefore, Cd, Ni, Cu, Pb, and Cr are obviously enriched in urban surface dust in Shaanxi Province, due to the influence of human activities. In addition, it can also be found that the non-carcinogen exposure risk in children is significantly higher than that in adults with the risk values of these five heavy metals all one order of magnitude higher than those of adults. Irrespective of whether addressing the results for children or adults, the non-carcinogen exposure doses of five heavy metals are sorted as Cr > Pb > Cu > Ni > Cd. According to the present situation, for a child, the total non-carcinogenic risk values of five heavy metals have exceeded the safety limit in 11 of the 20 leisure squares in Yanta District of Xi’an. That means the leisure squares are no longer suitable for physical and recreational activities. For the five heavy metals, the average non-carcinogenic risk value of Cr is largest, and causes the largest threat to health in Yanta District, Xi’an. The carcinogenic exposure doses of the heavy metals Cr, Cd, and Ni are very low in respiratory pathways and there is no carcinogenic health risk. In general, the Cr content in dust in domestic cities is higher than that of foreign cities; however, the Pb content is much lower.

Content of Heavy Metal in the Dust of Leisure Squares and Its Health Risk Assessment—A Case Study of Yanta District in Xi’an

Science.gov (United States)

Shao, Tianjie; Pan, Lihuan; Chen, Zhiqing; Wang, Ruiyuan; Li, Wenjing; Qin, Qing; He, Yuran

2018-01-01

Taking Yanta District in Xi’an as the research object, the present study measures the contents of Cadmium (Cd), Lead (Pb), Copper (Cu), Nickel (Ni), and Chromium (Cr) in dust samples and further assesses the health risk of heavy metals intake through dust based on the assessment method of human exposure risk proposed by U.S. EPA, with an aim to investigate the content of heavy metal in the dust of leisure squares and its exposure risk. As the results indicate, the average contents of five heavy metals are obviously higher than the soil background value in Shaanxi Province. Therefore, Cd, Ni, Cu, Pb, and Cr are obviously enriched in urban surface dust in Shaanxi Province, due to the influence of human activities. In addition, it can also be found that the non-carcinogen exposure risk in children is significantly higher than that in adults with the risk values of these five heavy metals all one order of magnitude higher than those of adults. Irrespective of whether addressing the results for children or adults, the non-carcinogen exposure doses of five heavy metals are sorted as Cr > Pb > Cu > Ni > Cd. According to the present situation, for a child, the total non-carcinogenic risk values of five heavy metals have exceeded the safety limit in 11 of the 20 leisure squares in Yanta District of Xi’an. That means the leisure squares are no longer suitable for physical and recreational activities. For the five heavy metals, the average non-carcinogenic risk value of Cr is largest, and causes the largest threat to health in Yanta District, Xi’an. The carcinogenic exposure doses of the heavy metals Cr, Cd, and Ni are very low in respiratory pathways and there is no carcinogenic health risk. In general, the Cr content in dust in domestic cities is higher than that of foreign cities; however, the Pb content is much lower. PMID:29495319

Assessment on the occupational exposure of urban public bus drivers to bioaccessible trace metals through resuspended fraction of settled bus dust

Energy Technology Data Exchange (ETDEWEB)

Gao, Peng [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States); Liu, Sa [Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA, 94720-7360 (United States); Ye, Wenyuan [Department of Chemical Engineering, KU Leuven, Willem de Croylaan 46, B-3001 Heverlee (Belgium); Lin, Nan; Meng, Ping [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Feng, Yujie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Zhang, Zhaohan; Cui, Fuyi; Lu, Binyu [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Xing, Baoshan [Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States)

2015-03-01

Limited information is available on the bioaccessible fraction of trace metals in the resuspended fraction of settled bus dust in order to estimate bus drivers ' occupational exposure. In this study, 45 resuspended fraction of settled dust samples were collected from gasoline and compressed natural gas (CNG) powered buses and analyzed for trace metals and their fraction concentrations using a three-step sequential extraction procedure. Experimental results showed that zinc (Zn) had the greatest bioaccessible fraction, recorded as an average of 608.53 mg/kg, followed in order of decreasing concentration by 129.80 mg/kg lead (Pb), 56.77 mg/kg copper (Cu), 34.03 mg/kg chromium (Cr), 22.05 mg/kg nickel (Ni), 13.17 mg/kg arsenic (As) and 2.77 mg/kg cadmium (Cd). Among the three settled bus dust exposure pathways, ingestion was the main route. Total exposure hazard index (HIt) for non-carcinogenic effect trace metals was lower than the safety level of 1. The incremental lifetime cancer risk (ILCR) for drivers was estimated for trace metal exposure. Pb and Ni presented relatively high potential risks in the non-carcinogenic and potentially carcinogenic health assessment for all drivers. ILCR was in the range of 1.84E − 05 to 7.37E − 05 and 1.74E − 05 to 6.95E − 05 for gasoline and CNG buses, respectively. - Highlights: • As, Cd and Ni had relatively higher bioaccessibility and mobility in the resuspended fraction of settled bus dust. • Bioaccessible metal concentrations were higher in gasoline-fueled buses than those in CNG-fueled buses. • The carcinogenic risk probabilities to drivers were around the acceptable level.

Indoor metallic pollution related to mining activity in the Bolivian Altiplano

International Nuclear Information System (INIS)

Fonturbel, Francisco E.; Barbieri, Enio; Herbas, Cristian; Barbieri, Flavia L.; Gardon, Jacques

2011-01-01

The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children. - Highlights: → We measured polymetallic pollution in household indoor dust from a mining town. → Toxic elements (Pb, As, Cd, Sb) in dust are correlated, suggesting a common origin. → The most polluted houses are within a 1 km radius around the mining center. → Carrying mining workwear home increases indoor pollution. → Lead concentrations in dust represent a serious concern for Public Health (600 μg/g). - In a typical Andean mining city, the urban indoor pollution with toxic metallic elements is directly related to the closeness of the mining activities.

Indoor metallic pollution related to mining activity in the Bolivian Altiplano

Energy Technology Data Exchange (ETDEWEB)

Fonturbel, Francisco E., E-mail: fonturbel@ug.uchile.cl [Departamento de Ciencias Ecologicas, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Barbieri, Enio [IRD-HSM (Institut de Recherche pour le Developpement), La Paz (Bolivia, Plurinational State of); Herbas, Cristian [Universidad Mayor de San Andres, IGEMA Institute (Instituto de Investigaciones Geologicas y del Medio Ambiente), La Paz (Bolivia, Plurinational State of); Barbieri, Flavia L.; Gardon, Jacques [IRD-HSM (Institut de Recherche pour le Developpement), La Paz (Bolivia, Plurinational State of); Universidad Mayor de San Andres, SELADIS Institute (Instituto de Servicios de Laboratorio para el Diagnostico e Investigacion en Salud), La Paz (Bolivia, Plurinational State of)

2011-10-15

The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children. - Highlights: > We measured polymetallic pollution in household indoor dust from a mining town. > Toxic elements (Pb, As, Cd, Sb) in dust are correlated, suggesting a common origin. > The most polluted houses are within a 1 km radius around the mining center. > Carrying mining workwear home increases indoor pollution. > Lead concentrations in dust represent a serious concern for Public Health (600 {mu}g/g). - In a typical Andean mining city, the urban indoor pollution with toxic metallic elements is directly related to the closeness of the mining activities.

Heavy Metal Pollution in Settled Dust Associated with Different Urban Functional Areas in a Heavily Air-Polluted City in North China

Science.gov (United States)

Wan, Dejun; Han, Zhangxiong; Yang, Jinsong; Yang, Guanglin; Liu, Xingqi

2016-01-01

Understanding variations of heavy metals in atmospheric particles between different functional areas is significant for pollution control and urban planning in cities. To reveal pollution and spatial distribution of heavy metals in atmospheric particles from different urban functional areas in Shijiazhuang in North China, 43 settled dust samples were collected over the main urban area and heavy metal concentrations were determined in their pollution indexes (IPIs) of the ten heavy metals are 2.7–13.6 (5.7 ± 2.2), suggesting high or very high pollution levels of most dust. Relatively lower IPIs occur mainly in the administration-education area, the commercial area, and other unclassified sites; while peaks occur mainly in the North Railway Station, the northeastern industrial area, and some sites near heavily trafficked areas, implying the significant influence of intensive industrial (including coal combustion) and traffic activities on atmospheric heavy metal accumulation. These results suggest a clear need of mitigating atmospheric heavy metal pollution via controlling emissions of toxic metals (especially Cd and Pb) from industrial and traffic sources in the city. PMID:27834903

Heavy Metal Pollution in Settled Dust Associated with Different Urban Functional Areas in a Heavily Air-Polluted City in North China.

Science.gov (United States)

Wan, Dejun; Han, Zhangxiong; Yang, Jinsong; Yang, Guanglin; Liu, Xingqi

2016-11-10

Understanding variations of heavy metals in atmospheric particles between different functional areas is significant for pollution control and urban planning in cities. To reveal pollution and spatial distribution of heavy metals in atmospheric particles from different urban functional areas in Shijiazhuang in North China, 43 settled dust samples were collected over the main urban area and heavy metal concentrations were determined in their pollution indexes (IPIs) of the ten heavy metals are 2.7-13.6 (5.7 ± 2.2), suggesting high or very high pollution levels of most dust. Relatively lower IPIs occur mainly in the administration-education area, the commercial area, and other unclassified sites; while peaks occur mainly in the North Railway Station, the northeastern industrial area, and some sites near heavily trafficked areas, implying the significant influence of intensive industrial (including coal combustion) and traffic activities on atmospheric heavy metal accumulation. These results suggest a clear need of mitigating atmospheric heavy metal pollution via controlling emissions of toxic metals (especially Cd and Pb) from industrial and traffic sources in the city.

Evaluation of dust and trace metal estimates from the Community Multiscale Air Quality (CMAQ model version 5.0

Directory of Open Access Journals (Sweden)

K. W. Appel

2013-07-01

Full Text Available The Community Multiscale Air Quality (CMAQ model is a state-of-the-science air quality model that simulates the emission, transformation, transport, and fate of the many different air pollutant species that comprise particulate matter (PM, including dust (or soil. The CMAQ model version 5.0 (CMAQv5.0 has several enhancements over the previous version of the model for estimating the emission and transport of dust, including the ability to track the specific elemental constituents of dust and have the model-derived concentrations of those elements participate in chemistry. The latest version of the model also includes a parameterization to estimate emissions of dust due to wind action. The CMAQv5.0 modeling system was used to simulate the entire year 2006 for the continental United States, and the model estimates were evaluated against daily surface-based measurements from several air quality networks. The CMAQ modeling system overall did well replicating the observed soil concentrations in the western United States (mean bias generally around ±0.5 μg m−3; however, the model consistently overestimated the observed soil concentrations in the eastern United States (mean bias generally between 0.5–1.5 μg m−3, regardless of season. The performance of the individual trace metals was highly dependent on the network, species, and season, with relatively small biases for Fe, Al, Si, and Ti throughout the year at the Interagency Monitoring of Protected Visual Environments (IMPROVE sites, while Ca, K, and Mn were overestimated and Mg underestimated. For the urban Chemical Speciation Network (CSN sites, Fe, Mg, and Mn, while overestimated, had comparatively better performance throughout the year than the other trace metals, which were consistently overestimated, including very large overestimations of Al (380%, Ti (370% and Si (470% in the fall. An underestimation of nighttime mixing in the urban areas appears to contribute to the overestimation of

A review on the importance of metals and metalloids in atmospheric dust and aerosol from mining operations.

Science.gov (United States)

Csavina, Janae; Field, Jason; Taylor, Mark P; Gao, Song; Landázuri, Andrea; Betterton, Eric A; Sáez, A Eduardo

2012-09-01

Contaminants can be transported rapidly and over relatively long distances by atmospheric dust and aerosol relative to other media such as water, soil and biota; yet few studies have explicitly evaluated the environmental implications of this pathway, making it a fundamental but understudied transport mechanism. Although there are numerous natural and anthropogenic activities that can increase dust and aerosol emissions and contaminant levels in the environment, mining operations are notable with respect to the quantity of particulates generated, the global extent of area impacted, and the toxicity of contaminants associated with the emissions. Here we review (i) the environmental fate and transport of metals and metalloids in dust and aerosol from mining operations, (ii) current methodologies used to assess contaminant concentrations and particulate emissions, and (iii) the potential health and environmental risks associated with airborne contaminants from mining operations. The review evaluates future research priorities based on the available literature and suggest that there is a particular need to measure and understand the generation, fate and transport of airborne particulates from mining operations, specifically the finer particle fraction. More generally, our findings suggest that mining operations play an important but underappreciated role in the generation of contaminated atmospheric dust and aerosol and the transport of metal and metalloid contaminants, and highlight the need for further research in this area. The role of mining activities in the fate and transport of environmental contaminants may become increasingly important in the coming decades, as climate change and land use are projected to intensify, both of which can substantially increase the potential for dust emissions and transport. Copyright © 2012 Elsevier B.V. All rights reserved.

A Review on the Importance of Metals and Metalloids in Atmospheric Dust and Aerosol from Mining Operations

Science.gov (United States)

Csavina, Janae; Field, Jason; Taylor, Mark P.; Gao, Song; Landázuri, Andrea; Betterton, Eric A.; Sáez, A. Eduardo

2012-01-01

Contaminants can be transported rapidly and over relatively long distances by atmospheric dust and aerosol relative to other media such as water, soil and biota; yet few studies have explicitly evaluated the environmental implications of this pathway, making it a fundamental but understudied transport mechanism. Although there are numerous natural and anthropogenic activities that can increase dust and aerosol emissions and contaminant levels in the environment, mining operations are notable with respect to the quantity of particulates generated, the global extent of area impacted, and the toxicity of contaminants associated with the emissions. Here we review (i) the environmental fate and transport of metals and metalloids in dust and aerosol from mining operations, (ii) current methodologies used to assess contaminant concentrations and particulate emissions, and (iii) the potential health and environmental risks associated with airborne contaminants from mining operations. The review evaluates future research priorities based on the available literature and suggest that there is a particular need to measure and understand the generation, fate and transport of airborne particulates from mining operations, specifically the finer particle fraction. More generally, our findings suggest that mining operations play an important but underappreciated role in the generation of contaminated atmospheric dust and aerosol and the transport of metal and metalloid contaminants, and highlight the need for further research in this area. The role of mining activities in the fate and transport of environmental contaminants may become increasingly important in the coming decades, as climate change and land use are projected to intensify, both of which can substantially increase the potential for dust emissions and transport. PMID:22766428

Dispersion and settlement of heavy metals in clay liners for sanitary landfills. Comparison of laboratory and field studies. Verlagerung und Festlegung von Schwermetallen in tonigen Deponieabdichtungen. Ein Vergleich von Labor- und Gelaendestudien

Energy Technology Data Exchange (ETDEWEB)

Wagner, J F

1992-01-01

The migration of heavy metals from long-standing waste dumps (blast furnace flue dust, ore flotation slurries, household refuse and toxic waste dumps) into natural clay barriers or artificial mineral liners was investigated in laboratory studies and field studies. (orig.)

Carburization behavior under the pits induced by metal dusting in 304L and 347 stainless steels

Energy Technology Data Exchange (ETDEWEB)

Chang, Chia-Hao [Department of Materials Engineering and Science, National Cheng Kung University, Tainan 701, Taiwan (China); Tsai, Wen-Ta, E-mail: wttsai@mail.ncku.edu.tw [Department of Materials Engineering and Science, National Cheng Kung University, Tainan 701, Taiwan (China)

2009-08-15

The metal dusting behavior of Type 304L and 347 stainless steels (SSs) in a flowing mixed CO/H{sub 2}/H{sub 2}O gas stream at 600 deg. C was investigated. After exposure in a 35% CO + 60% H{sub 2} + 5% H{sub 2}O gas for 500 h, large pits were formed on both steel surfaces. The aspect ratio of the pits formed in 304L SS was higher than that of the pits formed in 347 SS. The microstructures and chemical compositions of the reaction products and those of the substrate under the pits were examined by using a scanning electron microscope (SEM) combined with an energy dispersive spectrometer (EDS). A Cr-depleted zone containing voids was formed on the outer surface just beneath the pit. Massive matrix carburization and intergranular carbide precipitation were seen for both steels. The experimental results showed that niobium (Nb) could delay the ingress of carbon and retard the metal dusting reaction.

Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery.

Science.gov (United States)

Lewis, Ryan C; Gaffney, Shannon H; Le, Matthew H; Unice, Ken M; Paustenbach, Dennis J

2012-09-01

Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006. The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes. Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use. A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples. Of the long-term personal samples, airborne concentrations of metals ranged from refinery and perhaps other modern refineries during the timeframe examined. Copyright © 2011 Elsevier GmbH. All rights reserved.

Occurrence and levels of polybrominated diphenyl ethers (PBDEs) in house dust and hair samples from Northern Poland; an assessment of human exposure.

Science.gov (United States)

Król, Sylwia; Namieśnik, Jacek; Zabiegała, Bożena

2014-09-01

Polybrominated diphenyl ethers (PBDEs) are among most ubiquitous compounds to be found in indoor environment and ingestion of household dust is considered an important route of exposure to PBDEs, especially in toddlers and young children. The present work reported concentration levels of PBDE congeners (PBDE-28, -47, -99, -100, -153, -154, -183 and -209) in hair and dust samples from selected households from Northern Poland. The concentrations of PBDEs in dust ranged from human hair. PBDE-209 was reported the dominating congener. Two separated exposure scenarios (mean and 95th percentile) were used to provide a comprehensive overview of possible risks arising from ingestion of household dust. The estimated exposure to ∑PBDEs via ingestion of household dust varied from 21 to 92ngd(-1) in toddlers and from 3.7 to 20ngd(-1) in adults. By comparison of correlation between the concentrations of PBDEs in paired hair and dust samples the present work also investigated the possibility of use of hair for reflecting the actual exposure to PBDEs in humans. Finally the possible uncertainties associated with exposure assessment were investigated in the present study. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

75 FR 3881 - Combustible Dust

Science.gov (United States)

2010-01-25

..., rubber, drugs, dried blood, dyes, certain textiles, and metals (such as aluminum and magnesium..., furniture manufacturing, metal processing, fabricated metal products and machinery manufacturing, pesticide... standard that will comprehensively address the fire and explosion hazards of combustible dust. The Agency...

75 FR 32142 - Combustible Dust

Science.gov (United States)

2010-06-07

.... Contact Mat Chibbaro, P.E., Fire Protection Engineer, Office of Safety Systems, OSHA Directorate of..., and metals (such as aluminum and magnesium). Industries that may have combustible dust hazards include..., chemical manufacturing, textile manufacturing, furniture manufacturing, metal processing, fabricated metal...

Assessment of health risk of trace metal pollution in surface soil and road dust from e-waste recycling area in China.

Science.gov (United States)

Yekeen, Taofeek Akangbe; Xu, Xijin; Zhang, Yuling; Wu, Yousheng; Kim, Stephani; Reponen, Tiina; Dietrich, Kim N; Ho, Shuk-Mei; Chen, Aimin; Huo, Xia

2016-09-01

Informal recycling of e-waste and the resulting heavy metal pollution has become a serious burden on the ecosystem in Guiyu, China. In this investigation, we evaluated the trace metal concentration of community soil and road dust samples from 11 locations in Guiyu and 5 locations (consisting of residential areas, kindergarten/school, and farm field) in a reference area using graphite furnace atomic absorption spectrophotometer. The study spanned four seasons, 2012-2013, with a view to assess the risk associated with e-waste recycling in the study area. The concentrations of Pb, Cd, Cr, and Mn were 448.73, 0.71, 63.90, and 806.54 mg/kg in Guiyu soil and 589.74, 1.94, 69.71, and 693.74 mg/kg, in the dust, respectively. Pb and Cd values were significantly higher (P ≤ 0.05) than the reference area, and the mixed model analysis with repeated seasonal measurements revealed soil Pb and Cd levels that were 2.32 and 4.34 times, while the ratios for dust sample were 4.10 and 3.18 times higher than the reference area. Contamination factor, degree of contamination, and pollution load index indicated that all sampling points had a high level of metal contamination except farm land and kindergarten compound. The cumulative hazard index of Pb, Cd, Cr, and Mn for children in exposed area was 0.99 and 1.62 for soil and dust, respectively, suggesting non-cancer health risk potential. The significant accumulation of trace metals in the e-waste recycling area predisposes human life, especially children, to a potentially serious health risk.

Assessment of health risk of trace metal pollution in surface soil and road dust from e-waste recycling area in China

Science.gov (United States)

Yekeen, Taofeek Akangbe; Xu, Xijin; Zhang, Yuling; Wu, Yousheng; Kim, Stephani; Reponen, Tiina; Dietrich, Kim N.; Ho, Shuk-mei; Chen, Aimin; Huo, Xia

2017-01-01

Informal recycling of e-waste and the resulting heavy metal pollution has become a serious burden on the ecosystem in Guiyu, China. In this investigation, we evaluated the trace metals concentration of community soil and road dust samples from 11 locations in Guiyu and 5 locations (consists of residential areas, kindergarten/school and farm field) in a reference area using graphite furnace atomic absorption spectrophotometer. The study spanned four seasons, 2012–2013, with a view to assess the risk associated with e-waste recycling in the study area. The concentration of Pb, Cd, Cr and Mn were 448.73, 0.71, 63.90 and 806.54 mg/kg in Guiyu soil and 589.74, 1.94, 69.71 and 693.74 mg/kg, in the dust, respectively. Pb and Cd values were significantly higher (P≤ 0.05) than the reference area and the mixed model analysis with repeated seasonal measurements revealed soil Pb and Cd levels that were 2.32 and 4.34 times, while the ratios for dust sample were 4.10 and 3.18 times higher than the reference area. Contamination factor, degree of contamination and pollution load index indicated that all sampling points had high level of metal contamination except farm land and kindergarten compound. The cumulative hazard index of Pb, Cd, Cr and Mn for children in exposed area was 0.99 and 1.62 for soil and dust respectively, suggesting non-cancer health risk potential. The significant accumulation of trace metals in the e-waste recycling area predisposes human life, especially children, to a potentially serious health risk. PMID:27230155

Household Arthropod Allergens in Korea

Science.gov (United States)

Jeong, Kyoung Yong

2009-01-01

Arthropods are important in human health, which can transmit pathogens to humans, parasitize, or produce important allergens. Allergy prevalence becomes higher in Korea recently as well as other developed countries in contrast to a decrease of infectious diseases. Allergic diseases caused by household arthropods have increased dramatically during the last few decades since human beings spend more their time for indoor activities in modernized life style. Household arthropods are one of the most common causes of allergic diseases. Biological characterization of household arthropods and researches on their allergens will provide better understanding of the pathogenesis of allergic diseases and suggest new therapeutic ways. Therefore, studies on arthropods of allergenic importance can be considered one of the major research areas in medical arthropodology and parasitology. Here, the biology of several household arthropods, including house dust mites and cockroaches, the 2 most well known arthropods living indoor together with humans worldwide, and characteristics of their allergens, especially the research activities on these allergens performed in Korea, are summarized. PMID:19885330

Effects of Heavy Metals from Soil and Dust Source on DNA Damage of the Leymus chinensis Leaves in Coal-Mining Area in Northwest China.

Science.gov (United States)

Li, Tianxin; Zhang, Minjie; Lu, Zhongming; Herman, Uwizeyimana; Mumbengegwi, Dzivaidzo; Crittenden, John

2016-01-01

Air and soil pollution from mining activities has been considered as a critical issue to the health of living organisms. However, few efforts have been made in distinguishing the main pathway of organism genetic damage by heavy metals related to mining activities. Therefore, we investigated the genetic damage of Leymus chinensis leaf cells, the air particulate matter (PM) contents, and concentrations of the main heavy metals (Pb, Cd, Cr, Hg) in soil and foliar dust samples collected from seven experiment points at the core mining area and one control point 20 kilometers away from the core mining area in Inner Mongolia in 2013. Comet assay was used to test the genetic damage of the Leymus chinensis leaf cells; the Tail DNA% and Tail Moment were used to characterize the genetic damage degree of the plant cells. The comet assay results showed that the cell genetic damage ratio was up to 77.0% in experiment points but was only 35.0% in control point. The control point also had the slight Tail DNA% and Tail Moment values than other experiment groups. The cell damage degree of the control group was 0.935 and experiment groups were 1.299-1.815. The geo-accumulation index and comperehensive pollution index(CPI) were used to characterize heavy metal pollution in foliar dust samples, and single factor pollution index and CPI were used to characterize the heavy metal pollution in soil samples. The CPIfoliar dust of control group was 0.36 and experiment groups were 1.45-2.57; the CPIsoil of control group was 0.04 and experiment groups were 0.07-0.12. The results of correlation analyze showed that Air Quality Index (AQI) -CPIfoliar dust(r = 0.955**)>Damage degree-CPIfoliar dust(r = 0.923**)>Damage degree-AQI(r = 0.908**)>Damage degree-CPIsoil (r = 0.824*). The present research proved that mining activity had a high level of positive correlation with organism genetic damage caused by heavy metals through comparing with the control point; soil and atmosphere were both the

First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

DEFF Research Database (Denmark)

Saadi, Souheil; Hinnemann, Berit; Appel, Charlotte C.

2011-01-01

We investigate the structure and surface composition of the γ′-Ni3Al(111) and β-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel–aluminum alloys are protected...... by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni3Al and NiAl surfaces, the conditions under which CO and OH...... adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH...

Cosmological simulation with dust formation and destruction

Science.gov (United States)

Aoyama, Shohei; Hou, Kuan-Chou; Hirashita, Hiroyuki; Nagamine, Kentaro; Shimizu, Ikkoh

2018-06-01

To investigate the evolution of dust in a cosmological volume, we perform hydrodynamic simulations, in which the enrichment of metals and dust is treated self-consistently with star formation and stellar feedback. We consider dust evolution driven by dust production in stellar ejecta, dust destruction by sputtering, grain growth by accretion and coagulation, and grain disruption by shattering, and treat small and large grains separately to trace the grain size distribution. After confirming that our model nicely reproduces the observed relation between dust-to-gas ratio and metallicity for nearby galaxies, we concentrate on the dust abundance over the cosmological volume in this paper. The comoving dust mass density has a peak at redshift z ˜ 1-2, coincident with the observationally suggested dustiest epoch in the Universe. In the local Universe, roughly 10 per cent of the dust is contained in the intergalactic medium (IGM), where only 1/3-1/4 of the dust survives against dust destruction by sputtering. We also show that the dust mass function is roughly reproduced at ≲ 108 M⊙, while the massive end still has a discrepancy, which indicates the necessity of stronger feedback in massive galaxies. In addition, our model broadly reproduces the observed radial profile of dust surface density in the circum-galactic medium (CGM). While our model satisfies the observational constraints for the dust extinction on cosmological scales, it predicts that the dust in the CGM and IGM is dominated by large (>0.03 μm) grains, which is in tension with the steep reddening curves observed in the CGM.

Seasonal and occupational trends of five organophosphate pesticides in house dust.

Science.gov (United States)

Smith, Marissa N; Workman, Tomomi; McDonald, Katie M; Vredevoogd, Melinda A; Vigoren, Eric M; Griffith, William C; Thompson, Beti; Coronado, Gloria D; Barr, Dana; Faustman, Elaine M

2017-07-01

Since 1998, the University of Washington's Center for Child Environmental Health Risks Research has followed a community-based participatory research strategy in the Lower Yakima Valley of Washington State to assess pesticide exposure among families of Hispanic farmworkers. As a part of this longitudinal study, house dust samples were collected from both farmworker and non-farmworker households, across three agricultural seasons (thinning, harvest and non-spray). The household dust samples were analyzed for five organophosphate pesticides: azinphos-methyl, phosmet, malathion, diazinon, and chlorpyrifos. Organophosphate pesticide levels in house dust were generally reflective of annual use rates and varied by occupational status and agricultural season. Overall, organophosphate pesticide concentrations were higher in the thinning and harvest seasons than in the non-spray season. Azinphos-methyl was found in the highest concentrations across all seasons and occupations. Farmworker house dust had between 5- and 9-fold higher concentrations of azinphos-methyl than non-farmworker house dust. Phosmet was found in 5-7-fold higher concentrations in farmworker house dust relative to non-farmworker house dust. Malathion and chlorpyriphos concentrations in farmworker house dust ranged between 1.8- and 9.8-fold higher than non-farmworker house dust. Diazinon showed a defined seasonal pattern that peaked in the harvest season and did not significantly differ between farmworker and non-farmworker house dust. The observed occupational differences in four out of five of the pesticide residues measured provides evidence supporting an occupational take home pathway, in which workers may bring pesticides home on their skin or clothing. Further, these results demonstrate the ability of dust samples to inform the episodic nature of organophosphate pesticide exposures and the need to collect multiple samples for complete characterization of exposure potential.

Determination of heavy metals in air conditioner dust using FAAS and INAA

International Nuclear Information System (INIS)

Siddique, N.

2012-01-01

The elements Cd, Cr, Cu, Mn, Ni, Pb and Zn were determined in dust samples collected from air conditioner (AC) filters from 15 commercial sites of Lahore using flame atomic absorption spectroscopy (FAAS). The elements Cr, Mn and Zn were also determined using instrumental neutron activation analysis (INAA). The results obtained showed that higher amounts of these metals were measured in these dust samples than normally found in soil. This was especially true for Cd, Cu, Pb and Zn. Generally the amounts of Cd, Cr and Mn did not vary throughout the city of Lahore but the amounts of the traffic related Cu, Pb and Zn elements had the more variable ranges of 30-140, 30-230 and 74-2810 mg/kg respectively. The concentrations obtained for Cr, Mn and Zn by INAA were found to be higher than those obtained using FAAS. Analysis of the data obtained showed the digestion procedure employed to be the possible cause for this occurrence. It was also found that Mn was being over-estimated by INAA due to the interference from the Mg peak. (author)

The FMOS-COSMOS survey of star-forming galaxies at z ∼ 1.6. II. The mass-metallicity relation and the dependence on star formation rate and dust extinction

Energy Technology Data Exchange (ETDEWEB)

Zahid, H. J.; Sanders, D. B.; Chu, J.; Hasinger, G. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 (Japan); Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan); Kewley, L. J. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Daddi, E. [CEA-Saclay, Service d' Astrophysique, F-91191 Gif-sur-Yvette (France); Renzini, A. [INAF Osservatorio Astronomico di Padova, vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Rodighiero, G. [Dipartimento di Astronomia, Università di Padova, vicolo dell Osservatorio 3, I-35122 Padova (Italy); Nagao, T. [The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8302 (Japan); Arimoto, N. [National Astronomical Observatory of Japan, Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States); Kartaltepe, J. [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States); Lilly, S. J.; Carollo, C. M. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-strasse 27, 8093 Zürich (Switzerland); Maier, C. [Vienna University, Department of Astrophysics, Tuerkenschanzstrasse 17, 1180 Vienna (Austria); Geller, M. J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Capak, P. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Ilbert, O. [Aix Marseille Université, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, 13388, Marseille (France); Kajisawa, M., E-mail: jabran@ifa.hawaii.edu [Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho 2-5, Matsuyama, Ehime 790-8577 (Japan); Collaboration: COSMOS Team; and others

2014-09-01

We investigate the relationships between stellar mass, gas-phase oxygen abundance (metallicity), star formation rate (SFR), and dust content of star-forming galaxies at z ∼ 1.6 using Subaru/FMOS spectroscopy in the COSMOS field. The mass-metallicity (MZ) relation at z ∼ 1.6 is steeper than the relation observed in the local universe. The steeper MZ relation at z ∼ 1.6 is mainly due to evolution in the stellar mass where the MZ relation begins to turnover and flatten. This turnover mass is 1.2 dex larger at z ∼ 1.6. The most massive galaxies at z ∼ 1.6 (∼10{sup 11} M {sub ☉}) are enriched to the level observed in massive galaxies in the local universe. The MZ relation we measure at z ∼ 1.6 supports the suggestion of an empirical upper metallicity limit that does not significantly evolve with redshift. We find an anti-correlation between metallicity and SFR for galaxies at a fixed stellar mass at z ∼ 1.6, which is similar to trends observed in the local universe. We do not find a relation between stellar mass, metallicity, and SFR that is independent of redshift; rather, our data suggest that there is redshift evolution in this relation. We examine the relation between stellar mass, metallicity, and dust extinction, and find that at a fixed stellar mass, dustier galaxies tend to be more metal rich. From examination of the stellar masses, metallicities, SFRs, and dust extinctions, we conclude that stellar mass is most closely related to dust extinction.

[Gohieria fusca found in dust of air-conditioner filters].

Science.gov (United States)

Qiang, Chai; Xiao-Dong, Zhan; Wei, Guo; Chao-Pin, Li

2017-09-25

To investigate the pollution status of Gohieria fusca in the air conditioner-filters of different places in Wuhu City. The dust samples were collected from the filters of air-conditioners in dining rooms, shopping malls, hotels and households between June and September, 2013, and G. fusca was detected in the dust samples. There were 430 dust samples collected and 98 were G. fusca positive with the breeding rate of 22.79%. The difference of breeding rates of G. fusca were statistically significant among the different places ( χ 2 =18.294, P air-conditioner filters in Wuhu City gravely.

Exploring the Dust Content, Metallicity, Star Formation and AGN Activity in Distant Dusty, Star-Forming Galaxies Using Cosmic Telescope

Science.gov (United States)

Walth, Gregory; Egami, Eiichi; Clément, Benjamin; Rujopakarn, Wiphu; Rawle, Tim; Richard, Johan; Dessauges, Miroslava; Perez-Gonzalez, Pablo; Ebeling, Harald; Vayner, Andrey; Wright, Shelley; Cosens, Maren; Herschel Lensing Survey

2018-01-01

We present our recent ALMA observations of Herschel-detected gravitationally lensed dusty, star-forming galaxies (DSFGs) and how they compliment our near-infrared spectroscopic observations of their rest-frame optical nebular emission. This provides the complete picture of star formation; from the molecular gas that fuels star formation, to the dust emission which are the sites of star formation, and the nebular emission which is the gas excited by the young stars. DSFGs undergo the largest starbursts in the Universe, contributing to the bulk of the cosmic star formation rate density between redshifts z = 1 - 4. Internal processes within high-redshift DSFGs remains largely unexplored; such as feedback from star formation, the role of turbulence, gas surface density of molecular gas, AGN activity, and the rates of metal production. Much that is known about DSFGs star formation properties comes from their CO and dust emission. In order to fully understand the star formation history of DSFGs, it is necessary to observe their optical nebular emission. Unfortunately, UV/optical emission is severely attenuated by dust, making it challenging to detect. With the Herschel Lensing Survey, a survey of the cores of almost 600 massive galaxy clusters, we are able to probe faint dust-attenuated nebular emission. We are currently conducting a new survey using Keck/OSIRIS to resolve a sample of gravitationally lensed DSFGs from the Herschel Lensing Survey (>100 mJy, with SFRs >100 Msun/yr) at redshifts z=1-4 with magnifications >10x all with previously detected nebular emission lines. We present the physical and resolved properties of gravitationally lensed DSFGs at unprecedented spatial scales; such as ionization, metallicity, AGN activity, and dust attenuation.

The ecological risk, source identification, and pollution assessment of heavy metals in road dust: a case study in Rafsanjan, SE Iran.

Science.gov (United States)

Mirzaei Aminiyan, Milad; Baalousha, Mohammed; Mousavi, Rouhollah; Mirzaei Aminiyan, Farzad; Hosseini, Hamideh; Heydariyan, Amin

2018-05-01

Heavy metal (HM) contamination in road dust is a potential environmental and human health threat. The sources, concentrations, spatial distribution, and ecological risk of As, Cd, Cu, Cr, Ni, Pb, and Zn in road dust in Rafsanjan City, Iran, were investigated. Pollution was assessed using the enrichment factor (EF). The potentially harmful effects of HMs were evaluated by calculating the potential ecological risk factor of individual metals (E r ) and of multiple metals (RI) using the Hakanson method. Correlation and principal component analyses (PCA) were applied to identify HM pollution sources. The concentrations of HMs in road dust were higher (ca. 5-10 folds) than their natural background values. The EF and E r increased according to the following order Cu > Pb > As > Zn > Cd > Cr > Ni and Cu > Cd > Pb > As > Ni > Zn > Cr, respectively. Thus, Cu is regarded as the pollutant of highest concern. Based on potential ecological risk index (RI) spatial distribution, all parts of Rafsanjan are characterized by significantly high potential ecological risk. HM concentration heat maps, PCA, and correlation analysis suggest that Cu, Pb, As, Cd, and Zn may have originated from the same source and follow the same spatial distribution pattern. These metals originated mainly from anthropogenic sources like copper mining and smelting plants, industrial and chemical activities, inordinate application of chemical fertilizers and pesticides in farmlands, and heavy traffic. Ni and Cr are likely to origniate from the industrial activities and traffic load in Rafsanjan City.

Analysis of heavy metals in the re-suspended road dusts from different functional areas in Xi'an, China.

Science.gov (United States)

Wang, Qian; Lu, Xinwei; Pan, Huiyun

2016-10-01

A study on heavy metal pollution was undertaken in the re-suspended road dusts from different functional areas in Xi'an City of China to investigate the impacts of human activities and land uses on urban environment. The concentrations of Co, Cr, Cu, Mn, Ni, Pb, V, and Zn were determined using X-ray fluorescence spectrometry, and their accumulations were analyzed using enrichment factor. Correlation analysis, principal component analysis, and cluster analysis, combined with the concentration property and enrichment factor, were used to identify the possible sources of heavy metals investigated. The investigated re-suspended road dusts had Co, Cr, Cu, Pb, and Zn concentrations higher than background levels. Samples from different functional areas had diverse heavy metal concentration levels. Co, Cr, Cu, Pb, and Zn presented moderate/significant enrichment in the samples. The source analyses indicated that Mn, Ni, V, Pb, and Zn had the mixed sources of nature and traffic, Cr and Cu mainly originated from traffic source, while Co was primarily derived from construction source. Traffic and construction activities had a significant impact on urban environment. This preliminary research provides a valuable basis for urban environment protection and management.

GEOCHEMISTRY OF ATMOSPHERIC DUST ON THE TERRITORY OF THE CITY OF YEREVAN

Directory of Open Access Journals (Sweden)

Armen Saghatelyan

2012-06-01

Full Text Available This research is focused on the level of heavy metal contents in dust of a near-ground layer of atmosphere. The dust load level was evaluated as medial. Indicated was a quality composition of dominating dust pollutants. The level of summary load of metals was low.

Evaluation of the pollution and human health risks posed by heavy metals in the atmospheric dust in Ebinur Basin in Northwest China.

Science.gov (United States)

Abuduwailil, Jilili; Zhaoyong, Zhang; Fengqing, Jiang

2015-09-01

Recently, a large amount of research assessing pollution levels and the related health risks posed by atmosphere dust has been undertaken worldwide. However, little work has been done in the oases of the arid regions of Northwest China. In this paper, we studied the pollution and health risks over a year of seven heavy metals in the atmospheric dust of Ebinur Basin, a typical oasis in Northwest China. The results showed the following: (1) The annual amount of atmospheric deposition in Ebinur Basin was 298.23 g m(-2) and the average monthly atmospheric deposition was 25.06 g m(-2). The average and maximum values of the seven heavy metals measured were all below the National Soil Environmental Quality Standards (2nd). (2) Heavy metals of Cu, Cr, and As in the atmospheric deposition mainly originated from the natural geological background, while Zn came from human activity. This study also showed that among the seven measured heavy metals, the ratios of the no-pollution status of Pb, Cd, and Hg were higher than those of others with moderate degrees of pollution also accounting for a certain ratio. (3) The carcinogenic risks from As, Cd, and Cr were all lower than the corresponding standard limit values, and these metals are considered not harmful to the health of the basin. However, there is a relatively high risk of exposure for children from hand-to-mouth intake, which is worthy of attention. This research showed that both human activity and natural factors, such as wind and altitude, influenced the heavy metal contents in the atmospheric dust of the study area. Furthermore, recent human activity in the study area had the most negative influence on the accumulation of the heavy metals and the corresponding health risks, especially for Hg, Pb, and Cd, which is worthy of attention.

Assessment of ecological and human health risks of metals in urban road dust based on geochemical fractionation and potential bioavailability.

Science.gov (United States)

Jayarathne, Ayomi; Egodawatta, Prasanna; Ayoko, Godwin A; Goonetilleke, Ashantha

2018-09-01

Metals are one of the primary pollutants in the urban environment that pose adverse ecological and human health impacts. Therefore, the accurate quantification of the risk posed by metals is essential for developing effective risk management strategies to safeguard the urban environment. This study assessed the ecological and human health risks of six metals, commonly present in road dust by improving the original risk indices based on their potential bioavailability characteristics. The bioavailability of metals was determined by considering their distribution between the different geochemical phases of exchangeable, reducible, oxidisable and residual. The results of the modified risk analysis indicated that the road dust poses a low ecological risk in most of the study sites. According to the present situation, the non-cancer risk of individual metals for both, children and adults followed the decreasing trend of Pb > Cu > Cr > Zn > Ni > Cd. This study also found that depending on the particle size ranges, the potential of multiple metals being able to cause non-cancer health risk was low at most study sites. In terms of cancer health risk, Cr present at most of the study sites was found to be within the cancer threshold limit, even though the Cr content and the bioavailable fractions were relatively low. Copyright © 2018 Elsevier B.V. All rights reserved.

[Research on dust mite allergen gathered from filters of air-conditioners].

Science.gov (United States)

Zhan, Xiao-dong; Wu, Hua; Hu, Hui-min; Li, Chao-pin

2015-12-01

To discuss the relation between the dust mite allergen (Der) in air-conditioner filters and the asthma attack. The dust samples were collected from the filters of air-conditioners in dining rooms, shopping malls, hotels and households, respectively. The concentrations of Der f 1 and Der p1 were detected by ELISA, and the dust mite immune activities were determined by dot-ELISA. The concentrations of Der f 1 in the dining rooms, shopping malls, hotels and households were 1.52, 1.24, 1.31 µg/g and 1.46 µg/g respectively, and the concentrations of Der p 1 were 1.23, 1.12, 1.16 µg/ g and 1.18 µg, respectively. One hour after the running of air-conditioners, the concentrations of Der f 1 and Der p 1 in the air were higher than those before the running of air-conditioners, and the differences were significant (P air-conditioners in domestic houses in Wuhu City, and the allergens can induce asthma.

The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

Energy Technology Data Exchange (ETDEWEB)

Sparre, M.; Krühler, T.; Fynbo, J. P. U.; Watson, D. J.; De Ugarte Postigo, A.; Hjorth, J.; Malesani, D. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark); Hartoog, O. E.; Kaper, L. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); D' Elia, V. [INAF/Rome Astronomical Observatory, via Frascati 33, I-00040 Monteporzio Catone (Roma) (Italy); Zafar, T. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Afonso, P. M. J. [Physics and Astronomy Department, American River College, 4700 College Oak Drive, Sacramento, CA 95841 (United States); Covino, S. [INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Flores, H. [Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Universite Paris Diderot 5 place Jules Janssen, F-92195 Meudon (France); Goldoni, P. [APC, Astroparticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, Rue Alice Domon et Léonie Duquet, F-75205 Paris, Cedex 13 (France); Greiner, J. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 Reykjavik (Iceland); Klose, S. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Levan, A. J., E-mail: sparre@dark-cosmology.dk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); and others

2014-04-20

Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Lyα absorber with a very large neutral hydrogen column density of log N(H I)/cm{sup −2}=22.30±0.06 and a metallicity of [S/H] = –1.70 ± 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe II fine-structure lines have been detected. The afterglow is mildly reddened with A{sub V} = 0.11 ± 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.

Dust Combustion Safety Issues for Fusion Applications

Energy Technology Data Exchange (ETDEWEB)

L. C. Cadwallader

2003-05-01

This report summarizes the results of a safety research task to identify the safety issues and phenomenology of metallic dust fires and explosions that are postulated for fusion experiments. There are a variety of metal dusts that are created by plasma erosion and disruptions within the plasma chamber, as well as normal industrial dusts generated in the more conventional equipment in the balance of plant. For fusion, in-vessel dusts are generally mixtures of several elements; that is, the constituent elements in alloys and the variety of elements used for in-vessel materials. For example, in-vessel dust could be composed of beryllium from a first wall coating, tungsten from a divertor plate, copper from a plasma heating antenna or diagnostic, and perhaps some iron and chromium from the steel vessel wall or titanium and vanadium from the vessel wall. Each of these elements has its own unique combustion characteristics, and mixtures of elements must be evaluated for the mixture’s combustion properties. Issues of particle size, dust temperature, and presence of other combustible materials (i.e., deuterium and tritium) also affect combustion in air. Combustion in other gases has also been investigated to determine if there are safety concerns with “inert” atmospheres, such as nitrogen. Several coolants have also been reviewed to determine if coolant breach into the plasma chamber would enhance the combustion threat; for example, in-vessel steam from a water coolant breach will react with metal dust. The results of this review are presented here.

Bioaccessibility and health risk of arsenic, mercury and other metals in urban street dusts from a mega-city, Nanjing, China

International Nuclear Information System (INIS)

Hu Xin; Zhang, Yun; Luo Jun; Wang Tijian; Lian Hongzhen; Ding Zhuhong

2011-01-01

The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level ( -4 ). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults. - Highlights: → Spatial variation of elements in street dusts from different land use districts. → Oral bioaccessibility of elements in street dusts from different land use districts. → Human health risks of elements in street dusts from different land use districts. - Bioaccessibility and health risks of trace elements differed with street dusts from different land use districts in Nanjing.

Household hazardous waste

DEFF Research Database (Denmark)

Fjelsted, Lotte; Christensen, Thomas Højlund

2007-01-01

.) comprised 15-25% and foreign items comprised 10-20%. Water-based paint was the dominant part of the paint waste. The chemical composition of the paint waste and the paint-like waste was characterized by an analysis of 27 substances in seven waste fractions. The content of critical substances was tow......'Paint waste', a part of the 'household hazardous waste', amounting to approximately 5 tonnes was collected from recycling stations in two Danish cities. Sorting and analyses of the waste showed paint waste comprised approximately 65% of the mass, paint-like waste (cleaners, fillers, etc...... and the paint waste was less contaminated with heavy metals than was the ordinary household waste. This may suggest that households no longer need to source-segregate their paint if the household waste is incinerated, since the presence of a small quantity of solvent-based paint will not be harmful when...

Possibilities of Pelletizing and Briquetting of Dusts from Castings Grinding

Directory of Open Access Journals (Sweden)

A. Pribulová

2010-04-01

Full Text Available Foundry dust can be divided into three groups: metallic dust with Fe content over 70%, mixed dust with Fe or SiO2 content between 10 –70% and sand wastes with minimum content of SiO2 about 70%. Dust from castings grinding with high Fe content (87.9% is still landfillin Slovakia. The aim of experiments with dust from grinding has been to find the cheapest way of dust agglomeration with minimumamount of binder because of melting in the electric induction furnace. The dust was pelletized and briquetted and as binders bentonite, water glass and cement were used. Briquettes made from dust from grinding with addition of water glass got compression strength after three months on the air about 82 kPa. Briquettes with addition of water glass were melted together with cast iron in electric induction furnace. Yield of metal from briquettes was around 80% and slag quantity around 4% (without briquettes the slag quantity was 1.4%.

The influence of production routes on the metal dusting behavior of UNS N06025 plate, strip and tube

NARCIS (Netherlands)

Hattendorf, H.; Hermse, C.G.M.; Hannig, W.

2012-01-01

It is generally known that the production route influences the sensitivity of a material to metal dusting. In this study the different production states of UNS N06025 are compared as there are: plate deeply ground and 600 grit laboratory ground, strip as-delivered and 600 grit laboratory ground, and

Pollution characteristics, source apportionment, and health risk of heavy metals in street dust of Suzhou, China.

Science.gov (United States)

Lin, Manli; Gui, Herong; Wang, Yao; Peng, Weihua

2017-01-01

To analyze the pollution characteristics, source apportionment, and health risk of heavy metals (HMs) in street dust of Suzhou, China, 23 sampling sites were selected and periodically sampled for 12 months. A total of 276 samples were collected, and the concentrations of selected HMs (e.g., Cr, Cu, Fe, Mn, Pb, V, and Zn) were examined with an X-ray fluorescence spectrum analyzer. Results showed that the mean concentrations of Cr, Cu, Fe, Mn, Pb, V, and Zn in the street dust of Suzhou were 112.9, 27.5, 19941.3, 410.3, 45.2, 75.6, and 225.3 mg kg -1 , respectively. Cr, Cu, Pb, and Zn exceeded their background values in local natural soils by 1.3-3.6-fold, whereas Fe, Mn, and V were all within their background values. However, enrichment factor analysis revealed that Cr, Cu, Mn, Pb, V, and Zn, especially Cr, Cu, Pb, and Zn, were enriched in Suzhou street dust. The HMs showed no significant seasonal changes overall, but spatial distribution analysis implied that the high values of Cr, Cu, Mn, Pb, V, and Zn were mainly distributed in areas with frequent human activities. Results of multivariate techniques (e.g., Pearson correlation, hierarchical cluster, and principal components analyses) suggested that Pb and Zn had complicated sources; Cu and V mainly originated from traffic sources; Fe and Mn mainly came from natural sources; and Cr was dominantly related to industrial district. Health risk assessment revealed that a single heavy metal might not cause both non-cancer and carcinogenic risks to local residents. Nevertheless, the sum of the hazard index of all selected HMs for children slightly exceeded the safety value, thereby implying that the HMs from Suzhou street dust can possibly produce significant risk to children. Cr was the priority pollutant in the study area because of its high concentration, high enrichment, and high contribution to non-cancer risk values.

30 CFR 56.9315 - Dust control.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Dust control. 56.9315 Section 56.9315 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND... control. Dust shall be controlled at muck piles, material transfer points, crushers, and on haulage roads...

Human health risk assessment based on toxicity characteristic leaching procedure and simple bioaccessibility extraction test of toxic metals in urban street dust of Tianjin, China.

Directory of Open Access Journals (Sweden)

Binbin Yu

Full Text Available The potential ecological and human health risk related with urban street dust from urban areas of Tianjin, China was quantitatively analyzed using the method of toxicity characteristic leaching procedure (TCLP and simple bioaccessibility extraction test (SBET. In the study, Hakason index, Nemerow index (P, the hazard index (HI and the cancer risk index (RI were calculated to assess the potential risk. The sequence of potential ecological risk based on Hakason index was arsenic (As > cadmium (Cd > lead (Pb > copper (Cu > chromium (Cr, in particular, As and Cd were regarded as high polluted metals. While the results of extraction of TCLP were assessed using P, the sequence was As > Pb > Cd > Cr > Cu, which mean that As and Pb should be low polluted, and Cd, Cr and Cu would barely not polluted. For human health, total carcinogenic risk for children and adults was 2.01 × 10(-3 and 1.05 × 10(-3, respectively. This could be considered to be intolerable in urban street dust exposure. The sequence in the hazard quotient (HQ of each element was As > Cr > Pb > Cu > Cd. The HI value of these toxic metals in urban street dust for children and adults was 5.88 × 10(-1 and 2.80 × 10(-1, respectively. According to the characters of chemistry, mobility, and bioavailability of metals in urban street dust, we estimated the hazards on the environment and human health, which will help us to get more reasonable information for risk management of metals in urban environment.

Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

Energy Technology Data Exchange (ETDEWEB)

Jabran Zahid, H. [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kudritzki, Rolf-Peter; Ho, I-Ting [University of Hawaii at Manoa, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Conroy, Charlie [Department of Astronomy, Harvard University, Cambridge, MA, 02138 (United States); Andrews, Brett, E-mail: zahid@cfa.harvard.edu [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States)

2017-09-20

We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

International Nuclear Information System (INIS)

Jabran Zahid, H.; Kudritzki, Rolf-Peter; Ho, I-Ting; Conroy, Charlie; Andrews, Brett

2017-01-01

We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

Determinants of manganese levels in house dust samples from the CHAMACOS cohort

Energy Technology Data Exchange (ETDEWEB)

Gunier, R.B., E-mail: gunier@berkeley.edu [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States); Jerrett, M. [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States); Smith, D.R.; Jursa, T. [Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA (United States); Yousefi, P.; Camacho, J.; Hubbard, A.; Eskenazi, B.; Bradman, A. [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States)

2014-11-01

Introduction: Manganese (Mn) is an essential nutrient, but at high exposure levels Mn is a neurotoxicant. The fungicides maneb and mancozeb are approximately 21% Mn by weight and more than 150,000 kg are applied each year to crops in the Salinas Valley, California. It is not clear, however, whether agricultural use of these fungicides increases Mn levels in homes. Materials and methods: We collected house dust samples from 378 residences enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study with a second sample collected approximately nine months later from 90 of the residences. House dust samples were analyzed for Mn using inductively coupled plasma optical emission spectroscopy. Information from interviews, home inspections, and pesticide use reports was used to identify potential predictors of Mn dust concentrations and loadings. Results: Mn was detectable in all dust samples. The median Mn concentration was 171 μg/g and median Mn loading was 1,910 μg/m{sup 2} at first visit. In multivariable models, Mn dust concentrations and loadings increased with the number of farmworkers in the home and the amount of agricultural Mn fungicides applied within three kilometers of the residence during the month prior to dust sample collection. Dust concentrations of Mn and other metals (lead, cadmium and chromium) were higher in residences located in the southern Salinas Valley compared those located in other areas of the Salinas Valley. Dust loadings of Mn and other metals were also higher in residences located on Antioch Loam soil than other soil types, and in homes with poor or average housekeeping practices. Conclusions: Agricultural use of Mn containing fungicides was associated with Mn dust concentrations and loadings in nearby residences and farmworker homes. Housekeeping practices and soil type at residence were also important factors related to dust metal concentrations and loadings. - Highlights: • Manganese dust

Multi-element characterization and source identification of trace metal in road dust from an industrial city in semi-humid area of Northwest China

International Nuclear Information System (INIS)

Mengmeng Zhang; Xinwei Lu; Hao Chen; Panpan Gao; Yi Fu

2015-01-01

Concentrations and sources of multi-elements in road dusts from an industrial city of northwest China were determined. Dust samples have elevated concentrations of Co, Cr, Cu, Pb, Zn, Sr and Ba. The dusts were mainly moderate enrichment by Co and Pb, minimal enrichment to moderate enrichment by Sr and Zn, and deficiency to minimal enrichment by other trace metals. Mn, V, Y, La, Hf, Th and U originated from soil. Cu, Pb, Cr, Ba and Sr mainly derived from traffic. Co, Zr, Ni, Ga, As and Zn have mixed sources of nature, industry and traffic. (author)

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

International Nuclear Information System (INIS)

Boyer, M. L.; Gordon, K. D.; Meixner, M.; Sargent, B. A.; Srinivasan, S.; Riebel, D.; McDonald, I.; Van Loon, J. Th.; Clayton, G. C.; Sloan, G. C.

2012-01-01

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

Investigation of Dusts Effect and Negative Ion in DC Plasmas by Electric Probes

Science.gov (United States)

Oh, Hye Taek; Kang, Inje; Bae, Min-Keun; Park, Insun; Lee, Seunghwa; Jeong, Seojin; Chung, Kyu-Sun

2017-10-01

Dust is typically negatively charged by electron attachment whose thermal velocities are fast compared to that of the heavier ions. The negatively charged particles can play a role of negative ions which affect the quasi-neutrality of background plasma. To investigate effect of metal dusts and negative ion on plasma and materials, metal dusts are injected into background Ar plasma which is generated by tungsten filament using dust dispenser on Cubical Plasma Device (CPD). The CPD has following conditions: size =24x24x24cm3, plasma source =DC filament plasma (ne 1x10x1010, Te 2eV), background gas =Ar, dusts =tungsten powder (diameter 1.89micron). The dust dispenser is developed to quantitate of metal dust by ultrasonic transducer. Electronegative plasmas are generated by adding O2 + Ar plasma to compare negative ion and dust effect. A few grams of micron-sized dusts are placed in the dust dispenser which is located at the upper side of the Cubical Plasma Device. The falling particles by dust dispenser are mainly charged up by the collection of the background plasma. The change in parameters due to negative ion production are characterized by measuring the floating and plasma potential, electron temperature and negative ion density using electric probes.

Extinction Mapping and Dust-to-Gas Ratios of Nearby Galaxies using LEGUS

Science.gov (United States)

Kahre, Lauren; Walterbos, Rene; Kim, Hwihyun; Thilker, David; Lee, Janice; LEGUS Team

2018-01-01

Dust is commonly used as a tracer for cold dense gas, either through IR and NIR emission maps or through extinction mapping, and dust abundance and gas metallicity are critical constraints for chemical and galaxy evolution models. Extinction mapping has been used to trace dust column densities in the Milky Way, the Magellanic Clouds, and M31. The maps for M31 use IR and NIR photometry of red giant branch stars, which is more difficult to obtain for more distant galaxies. Work by Kahre et al. (in prep) uses the extinctions derived for individual massive stars using the isochrone-matching method described by Kim et al. (2012) to generate extinction maps for these more distant galaxies.Isochrones of massive stars lie in the same location on a color-color diagram with little dependence on metallicity and luminosity class, so the extinction can be directly derived from the observed photometry. We generate extinction maps using photometry of massive stars from the Hubble Space Telescope for several of the nearly 50 galaxies observed by the Legacy Extragalactic Ultraviolet Survey (LEGUS). The derived extinction maps will allow us to correct ground-based and HST Halpha maps for extinction, and will be used to constrain changes in the dust-to-gas ratio across the galaxy sample and in different star formation, metallicity and morphological environments. Previous studies have found links between galaxy metallicity and the dust-to-gas mass ratio. We present a study of LEGUS galaxies spanning a range of distances, metallicities, and galaxy morphologies, expanding on our previous study of metal-poor dwarfs Holmberg I and II and giant spirals NGC 6503 and NGC 628. We see clear evidence for changes in the dust-to-gas mass ratio with changing metallicity. We also examine changes in the dust-to-gas mass ratio with galactocentric radius. Ultimately, we will provide constraints on the dust-to-gas mass ratio across a wide range of galaxy environments.

Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings.

Science.gov (United States)

Beamer, P I; Sugeng, A J; Kelly, M D; Lothrop, N; Klimecki, W; Wilkinson, S T; Loh, M

2014-05-01

Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites.

Long-term Geochemical Evolution of Lithogenic Versus Anthropogenic Distribution of Macro and Trace Elements in Household Attic Dust.

Science.gov (United States)

Balabanova, Biljana; Stafilov, Trajče; Šajn, Robert; Tănăselia, Claudiu

2017-01-01

Attic dusts were examined as historical archives of anthropogenic emissions, with the goal of elucidating the enrichment pathways associated with hydrothermal exploitation of Cu, Pb, and Zn minerals in the Bregalnica River basin in the eastern part of the Republic of Macedonia. Dust samples were collected from 84 settlements. Atomic emission spectrometry and mass spectrometry with inductively coupled plasma were applied as analytical techniques for the determination of 69 element contents. Multivariate analysis was applied for the extraction of dominant geochemical markers. The lithogenic distribution was simplified to six dominant geochemical markers: F1: Ga-Nb-Ta-Y-(La-Gd)-(Eu-Lu); F2: Be-Cr-Li-Mg-Ni; F3: Ag-Bi-Cd-Cu-In-Mn-Pb-Sb-Te-W-Zn; F4: Ba-Cs-Hf-Pd-Rb-Sr-Tl-Zr; F5: As-Co-Ge-V; and F6: К-Na-Sc-Ti. The anthropogenic effects on the air pollution were marked by a dominance of F3 and secondary dominance of F5. The fifth factor also was determined as a lithogenic marker for the occurrence of the very old Rifeous shales. The first factor also presents a very unique association that despite the heterogeneity relays on natural phenomena of tracking the deposition in areas of Proterosoic gneisses; related to the distribution of fine particles was associated with carbonate-silicate volcanic rocks. Intensive poly-metallic dust depositions were recorded only in the surroundings of localities where the hydrothermal extractions are implemented. Long-term deposition can be considered as pollution indexes for these hot spots. This mainly affects the Cd, Pb, and Zn deposition that is as high as 25, 3900, and 3200 mg/kg, respectively.

Control of house-dust mites with home disinfectants

NARCIS (Netherlands)

Schober, G.; Wetter, G.; Bischoff, E.; Bronswijk, van J.E.M.H.; Kniest, F.M.

1987-01-01

Chemical disinfectants and biocidal preparations used in households were tested in the laboratory for their ability to kill the house-dust miteDermatophagoides farinae. Batches of ten specimens were soaked in aqueous solutions or suspensions containing 0.0, 0.1, 0.3, 1.0, 3.0 and 10.0% (by volume)

Factors of influence on body lead and cadmium levels in regions of Saxony Anhalt with different pollution levels, with special consideration to heavy metal uptake via household dust; Einflussfaktoren auf die innere Blei- und Cadmiumbelastung in unterschiedlich belasteten Regionen Sachsen-Anhalts unter besonderer Beruecksichtigung der Schwermetallaufnahme ueber den Hausstaub

Energy Technology Data Exchange (ETDEWEB)

Meyer, I.

2002-07-01

The present study is based on data from an environmental medicine study aimed at identifying possible health impairments in the population of Hettstedt, a metallurgical industry site, as compared with those of the industrial region of Bitterfeld and Zerbst as control region. The present study was designed as a six-year longitudinal study and based on three regional cross-sectional studies performed in school years 1992/93, 1995/96 and 1998/99. In all three of these surveys the study population was recruited from children just entering school (5 to 7 years), 3rd form (8 to 10 years) and 6th form school children. The study population of the first survey also included women aged 50 to 59. The goal of the present study was to identify predictors of lead and cadmium deposition in households of children from Hettstedt and women from Hettstedt, Bitterfeld and Zerbst. Furthermore, the extent to which body lead and cadmium levels are influenced by the deposition of these heavy metals in household dust and the possibility of a change in children's lead and cadmium body levels between 1992/93 and 1998/99 were explored. Body lead levels were measured in terms of blood lead levels, which reflect the exposure over the past few weeks. The most significant determinants of lead deposition in household dust was the proximity of the home to the metallurgical plants and factors reflecting the deposition of lead-containing dust in the home. Likewise, the main determinants of body lead levels were the proximity of the home to emitters and, in the case of children, the lead content of household dust associated with this and the whirling up of dust by pets. Boys were found to have markedly higher levels than girls. Whereas drinking lead-containing water and being in the garden had no demonstrable effect on body lead levels in children, in women these factors were found to play a significant role, along with smoking and the release of lead from the bones after the menopause. Body lead

Response of the Eastern Mediterranean microbial ecosystem to dust and dust affected by acid processing in the atmosphere

Directory of Open Access Journals (Sweden)

Michael David Krom

2016-08-01

Full Text Available Acid processes in the atmosphere, particularly those caused by anthropogenic acid gases, increase the amount of bioavailable P in dust and hence are predicted to increase microbial biomass and primary productivity when supplied to oceanic surface waters. This is likely to be particularly important in the Eastern Mediterranean Sea (EMS, which is P limited during the winter bloom and N&P co-limited for phytoplankton in summer. However, it is not clear how the acid processes acting on Saharan dust will affect the microbial biomass and primary productivity in the EMS. Here, we carried out bioassay manipulations on EMS surface water on which Saharan dust was added as dust (Z, acid treated dust (ZA, dust plus excess N (ZN and acid treated dust with excess N (ZNA during springtime (May 2012 and measured bacterioplankton biomass, metabolic and other relevant chemical and biological parameters. We show that acid treatment of Saharan dust increased the amount of bioavailable P supplied by a factor of ~40 compared to non-acidified dust (18.4 nmoles P mg-1 dust vs. 0.45 nmoles P mg-1 dust, respectively. The increase in chlorophyll, primary and bacterial productivity for treatments Z and ZA were controlled by the amount of N added with the dust while those for treatments ZN and ZNA (in which excessive N was added were controlled by the amount of P added. These results confirm that the surface waters were N&P co-limited for phytoplankton during springtime. However, total chlorophyll and primary productivity in the acid treated dust additions (ZA and ZNA were less than predicted from that calculated from the amount of the potentially limiting nutrient added. This biological inhibition was interpreted as being due to labile trace metals being added with the acidified dust. A probable cause for this biological inhibition was the addition of dissolved Al, which forms potentially toxic Al nanoparticles when added to seawater. Thus, the effect of anthropogenic acid

Desert Dust and Health: A Central Asian Review and Steppe Case Study

Directory of Open Access Journals (Sweden)

Troy Sternberg

2017-11-01

Full Text Available In Asian deserts environmental and anthropomorphic dust is a significant health risk to rural populations. Natural sources in dry landscapes are exacerbated by human activities that increase the vulnerability to dust and dust-borne disease vectors. Today in Central and Inner Asian drylands, agriculture, mining, and rapid development contribute to dust generation and community exposure. Thorough review of limited dust investigation in the region implies but does not quantify health risks. Anthropogenic sources, such as the drying of the Aral Sea, highlight the shifting dust dynamics across the Central EurAsian steppe. In the Gobi Desert, our case study in Khanbogd, Mongolia addressed large-scale mining’s potential dust risk to the health of the local population. Dust traps showed variable exposure to particulates among herder households and town residents; dust density distribution indicated that sources beyond the mine need to be considered when identifying particulate sources. Research suggests that atmospheric dust from multiple causes may enhance human particulate exposure. Greater awareness of dust in greater Central Asia reflects community concern about related health implications. Future human well-being in the region will require more thorough information on dust emissions in the changing environment.

Desert Dust and Health: A Central Asian Review and Steppe Case Study.

Science.gov (United States)

Sternberg, Troy; Edwards, Mona

2017-11-03

In Asian deserts environmental and anthropomorphic dust is a significant health risk to rural populations. Natural sources in dry landscapes are exacerbated by human activities that increase the vulnerability to dust and dust-borne disease vectors. Today in Central and Inner Asian drylands, agriculture, mining, and rapid development contribute to dust generation and community exposure. Thorough review of limited dust investigation in the region implies but does not quantify health risks. Anthropogenic sources, such as the drying of the Aral Sea, highlight the shifting dust dynamics across the Central EurAsian steppe. In the Gobi Desert, our case study in Khanbogd, Mongolia addressed large-scale mining's potential dust risk to the health of the local population. Dust traps showed variable exposure to particulates among herder households and town residents; dust density distribution indicated that sources beyond the mine need to be considered when identifying particulate sources. Research suggests that atmospheric dust from multiple causes may enhance human particulate exposure. Greater awareness of dust in greater Central Asia reflects community concern about related health implications. Future human well-being in the region will require more thorough information on dust emissions in the changing environment.

Carbon Formation and Metal Dusting in Hot-Gas Cleanup Systems of Coal Gasifiers

Energy Technology Data Exchange (ETDEWEB)

Tortorelli, Peter F.; Judkins, Roddie R.; DeVan, Jackson H.; Wright, Ian G.

1995-12-31

There are several possible materials/systems degradation modes that result from gasification environments with appreciable carbon activities. These processes, which are not necessarily mutually exclusive, include carbon deposition, carburization, metal dusting, and CO disintegration of refractories. Carbon formation on solid surfaces occurs by deposition from gases in which the carbon activity (a sub C) exceeds unity. The presence of a carbon layer CO can directly affect gasifier performance by restricting gas flow, particularly in the hot gas filter, creating debris (that may be deposited elsewhere in the system or that may cause erosive damage of downstream components), and/or changing the catalytic activity of surfaces.

Heavy metals in moss samples exposed to tHe atmospHeric dust after eruption of eyjafjallajökull volcano

Directory of Open Access Journals (Sweden)

Patryk Ochota

2012-03-01

Full Text Available Background: Volcanic ash, which is ejected during volcanic eruptions, flies in the air and spreads by the wind over large distances. It is a magmatic source and as such may contain heavy metals. The aim of the study was to carry out investigation on heavy metal content: Pb, Cd, Zn, Fe, Mn, Cu and Cr in samples of moss bags exposed to atmospheric dust containing volcanic ash in Sosnowiec (Poland after eruption of Eyjafjallajökull volcano in Iceland. Materials and methods: Samples have been exposed to atmospheric dust after volcanic eruption for 2 months, and were mineralised in 70% HNO3 and 30% H2O2. The content of Pb and Cd was analysed by atomic absorption spectrometry with electrothermal atomization (ETAAS and Zn, Fe, Mn, Cu, Cr by atomic absorption spectrometry with flame atomization (FAAS. Results: During the experiment the content of lead in samples of moss increased by 54,9 μg/g, cadmium by 3,41 μg/g, manganese by 150 μg/g, iron by 6,09 mg/g, zinc by 514 μg/g, copper by 20,77 μg/g and chromium by 6,99 μg/g. Conclusions: In Sosnowiec the comparable increase of metal content was from several to 41 times higher than in the areas not exposed to volcanic ash. It indicates that volcanic ash can be a potential source of heavy metals in the environment and, consequently, affect our health.

Dissolution of heavy metals from electrostatic precipitator (ESP) dust ...

African Journals Online (AJOL)

Coal based sponge iron industries in India generate considerable quantity of solid waste, 40% of which is flue dust produced from the electrostatic precipitator (ESP) connected to rotary kiln. This paper reports the dissolution of Zn, Cu, Pb, Mn and Fe from the ESP dust using three fungal species, Aspergillus niger, ...

Electrolytic recuperation of heavy metals and chlorine from fly-ashes and washwater of a household incinerator

Energy Technology Data Exchange (ETDEWEB)

Maes, H.; Carpels, M.; Elslander, H.; Van Houtven, D.; Vereecken, J.; Kinnaer, L.; Hermans, N.; Gielen, C.; Van Kerckhoven, M.; Raats, L. [Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (Belgium)

1995-12-31

The treatment and processing of the residues which result from the household incineration process were investigated in a study conducted in Belgium. Incineration produces large amounts of solid residue, particularly fly-ash, which contains a large degree of heavy metals. Also, the large amount of acid washwater flow which comes from the gas washer is highly concentrated with chlorine, and heavy metals. Presently, both the fly-ash and the wastewater are dumped at disposal sites. Two objectives for waste management were presented. The first was to improve the fly-ash for potential use as, for example, filler in road surfaces. The second was to reduce the wastewater flow and to use neutralizing reagents or an electro-chemical treatment on the washwater, in order to recuperate the chlorine. The fly-ash was treated by leaching with the acid washwater. The leached heavy metals were recuperated by electrolysis. It was concluded, however, that electrolytic recuperation of heavy metals from fly ash was not economically feasible. 2 refs., 7 tabs., 8 figs.

Dust, Climate, and Human Health

Science.gov (United States)

Maynard, Nancy G.

2003-01-01

Air pollution from both natural and anthropogenic causes is considered to be one of the most serious world-wide environment-related health problems, and is expected to become worse with changes in the global climate. Dust storms from the atmospheric transport of desert soil dust that has been lifted and carried by the winds - often over significant distances - have become an increasingly important emerging air quality issue for many populations. Recent studies have shown that the dust storms can cause significant health impacts from the dust itself as well as the accompanying pollutants, pesticides, metals, salt, plant debris, and other inorganic and organic materials, including viable microorganisms (bacteria, viruses and fungi). For example, thousands of tons of Asian desert sediments, some containing pesticides and herbicides from farming regions, are commonly transported into the Arctic during dust storm events. These chemicals have been identified in animal and human tissues among Arctic indigenous populations. Millions of tons of airborne desert dust are being tracked by satellite imagery, which clearly shows the magnitude as well as the temporal and spatial variability of dust storms across the "dust belt" regions of North Africa, the Middle East, and China. This paper summarizes the most recent findings on the effects of airborne desert dust on human health as well as potential climate influences on dust and health.

NEW ULTRAVIOLET EXTINCTION CURVES FOR INTERSTELLAR DUST IN M31

Energy Technology Data Exchange (ETDEWEB)

Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Gordon, Karl D.; Bohlin, R. C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bianchi, Luciana C. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Massa, Derck L.; Wolff, Michael J. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Fitzpatrick, Edward L., E-mail: gclayton@fenway.phys.lsu.edu, E-mail: bohlin@stsci.edu, E-mail: kgordon@stsci.edu, E-mail: bianchi@jhu.edu, E-mail: mjwolff@spacescience.org, E-mail: edward.fitzpatrick@villanova.edu [Department of Astronomy and Astrophysics, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085 (United States)

2015-12-10

New low-resolution UV spectra of a sample of reddened OB stars in M31 were obtained with the Hubble Space Telescope/STIS to study the wavelength dependence of interstellar extinction and the nature of the underlying dust grain populations. Extinction curves were constructed for four reddened sightlines in M31 paired with closely matching stellar atmosphere models. The new curves have a much higher signal-to-noise ratio than previous studies. Direct measurements of N(H i) were made using the Lyα absorption lines enabling gas-to-dust ratios to be calculated. The sightlines have a range in galactocentric distance of 5–14 kpc and represent dust from regions of different metallicities and gas-to-dust ratios. The metallicities sampled range from solar to 1.5 solar. The measured curves show similarity to those seen in the Milky Way and the Large Magellanic Cloud. The Maximum Entropy Method was used to investigate the dust composition and size distribution for the sightlines observed in this program, finding that the extinction curves can be produced with the available carbon and silicon abundances if the metallicity is super-solar.

Heavy metal accumulation related to population density in road dust samples taken from urban sites under different land uses

NARCIS (Netherlands)

Trujillo-González, Juan Manuel; Torres-Mora, Marco Aurelio; Keesstra, Saskia; Brevik, Eric C.; Jiménez-Ballesta, Raimundo

2016-01-01

Soil pollution is a key component of the land degradation process, but little is known about the impact of soil pollution on human health in the urban environment. The heavy metals Pb, Zn, Cu, Cr, Cd and Ni were analyzed by acid digestion (method EPA 3050B) and a total of 15 dust samples were

Canadian House Dust Study: Population-based concentrations, loads and loading rates of arsenic, cadmium, chromium, copper, nickel, lead, and zinc inside urban homes

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Pat E. [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Levesque, Christine [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Chénier, Marc; Gardner, H. David [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Jones-Otazo, Heather [Regions and Programs Branch, Health Canada, 180 Queen Street West, Toronto, ON, Canada M5V 3L7 (Canada); Petrovic, Sanya [Contaminated Sites Division, Healthy Environments and Consumer Safety Branch, Health Canada, 269 Laurier Ave West, Ottawa, ON, Canada K1A 0K9 (Canada)

2013-01-15

The Canadian House Dust Study was designed to obtain nationally representative urban house dust metal concentrations (μg g{sup −1}) and metal loadings (μg m{sup −2}) for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Consistent sampling of active dust of known age and provenance (area sampled) also permitted the calculation of indoor loading rates (mg m{sup −2} day{sup −1} for dust and μg m{sup −2} day{sup −1} for metals) for the winter season (from 2007 to 2010) when houses are most tightly sealed. Geomean/median indoor dust loading rates in homes located more than 2 km away from industry of any kind (9.6/9.1 mg m{sup −2} day{sup −1}; n = 580) were significantly lower (p < .001) than geomean (median) dust loading rates in homes located within 2 km of industry (13.5/13.4 mg m{sup −2} day{sup −1}; n = 421). Proximity to industry was characterized by higher indoor metal loading rates (p < .003), but no difference in dust metal concentrations (.29 ≥ p ≤ .97). Comparisons of non-smokers' and smokers' homes in non-industrial zones showed higher metal loading rates (.005 ≥ p ≤ .038) in smokers' homes, but no difference in dust metal concentrations (.15 ≥ p ≤ .97). Relationships between house age and dust metal concentrations were significant for Pb, Cd and Zn (p < .001) but not for the other four metals (.14 ≥ p ≤ .87). All seven metals, however, displayed a significant increase in metal loading rates with house age (p < .001) due to the influence of higher dust loading rates in older homes (p < .001). Relationships between three measures of metals in house dust – concentration, load, and loading rate – in the context of house age, smoking behavior and urban setting consistently show that concentration data is a useful indicator of the presence of metal sources in the home, whereas dust mass is the overriding influence on metal loadings and loading rates

Evaluation of Levels, Sources and Health Hazards of Road-Dust Associated Toxic Metals in Jalalabad and Kabul Cities, Afghanistan.

Science.gov (United States)

Jadoon, Waqar Azeem; Khpalwak, Wahdatullah; Chidya, Russel Chrispine Garven; Abdel-Dayem, Sherif Mohamed Mohamed Ali; Takeda, Kazuhiko; Makhdoom, Masood Arshad; Sakugawa, Hiroshi

2018-01-01

This study was designed to investigate selected road-dust associated heavy metals, their relations with natural and anthropogenic sources, and potential human and environmental health risks. For this purpose, 42 and 36 road-dusts samples were collected from Jalalabad and Kabul cities (Afghanistan), respectively. The following elements were found in descending concentrations: Mn, Zn, Pb, Ni, Cu, Cr, Co, and Cd in Jalalabad; and Mn, Zn, Ni, Cu, Cr, Pb, Co, and Cd in Kabul. Except for Ni, all the elemental contents were less than the Canadian permissible limits in residential/parkland soils. Principle Component Analysis and enrichment of Cd, Cu, Ni, Pb, and Zn pointed to anthropogenic sources, whereas Co, Cr, and Mn indicated crustal inputs. Broadly, Cd monomial risk index ([Formula: see text]) was considerable; however, one site each in both cities showed high risk ([Formula: see text] ≥ 350). The potential ecological risk (RI) is mostly low; however, at some sites, the risk was considerable. Ingestion appeared to be the main exposure route (99%) for heavy metals and contributed > 90% to noncancerous (all residents), as well as 92% (children) and 75-89% (adults) cancerous risks. The noncancerous risks of all metals and their integrated risks for all residents were within acceptable levels. Moreover, potential cancer risks in children from Ni and Cr were slightly higher than the US-EPA safe levels but were within acceptable levels for adults. This study found higher risks to children and therefore recommends proper management and ways to control metals pollution load in these areas to decrease human health and RIs.

Occurrence of trace elements in respirable coal dust

International Nuclear Information System (INIS)

Sahoo, B.N.

1991-01-01

Inhalation of fine particles of coal dust contributes significantly to the occurrence of the disease, pneumoconiosis, prevailing in coal mining community. It is not presently known whether only the coal dust or specific chemical compounds or synergistic effects of several compounds associated with respirable coal dust is responsible for the disease, pneumoconiosis. The present paper describes the quantitative determination of ten minor and trace elements in respirable coal dust particles by atomic absorption spectrophotometric methods. The respirable coal dust samples are collected at the mine atmosphere during drilling in coal scams by using Messrs. Casella's Hexlet apparatus specially designed and fitted with horizontal elutriator to collect the respirable coal dust fraction simulating as near as possible to the lung's retention of the coal miners. After destruction of organic matter by wet oxidation and filtering off clay and silica, Fe, Ca, Mg, Na, K, Mn, Cu, Zn, Cd, and Ni were determined directly in the resulting solution by atomic absorption spectrophotometric procedures. The results show that the trace metals are more acute in lower range of size spectrum. Correlation coefficient, enrichment factor and linear regression values and their inverse relationship between the slope and EF values suggest that, in general, the trace metals in respirable particulates are likely to be from coal derived source if their concentrations are likewise high in the coal. The trace metal analytical data of respirable particulates fitted well to the linear regressive equation. The results of the studies are of importance as it may throw some light on the respirable lung disease 'pneumoconiosis' which are predominant in coal mining community. (author). 13 refs., 6 tabs

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

Directory of Open Access Journals (Sweden)

C. M. Archuleta

2005-01-01

Full Text Available This study examines the potential role of some types of mineral dust and mineral dust with sulfuric acid coatings as heterogeneous ice nuclei at cirrus temperatures. Commercially-available nanoscale powder samples of aluminum oxide, alumina-silicate and iron oxide were used as surrogates for atmospheric mineral dust particles, with and without multilayer coverage of sulfuric acid. A sample of Asian dust aerosol particles was also studied. Measurements of ice nucleation were made using a continuous-flow ice-thermal diffusion chamber (CFDC operated to expose size-selected aerosol particles to temperatures between -45 and -60°C and a range of relative humidity above ice-saturated conditions. Pure metal oxide particles supported heterogeneous ice nucleation at lower relative humidities than those required to homogeneously freeze sulfuric acid solution particles at sizes larger than about 50 nm. The ice nucleation behavior of the same metal oxides coated with sulfuric acid indicate heterogeneous freezing at lower relative humidities than those calculated for homogeneous freezing of the diluted particle coatings. The effect of soluble coatings on the ice activation relative humidity varied with the respective uncoated core particle types, but for all types the heterogeneous freezing rates increased with particle size for the same thermodynamic conditions. For a selected size of 200 nm, the natural mineral dust particles were the most effective ice nuclei tested, supporting heterogeneous ice formation at an ice relative humidity of approximately 135%, irrespective of temperature. Modified homogeneous freezing parameterizations and theoretical formulations are shown to have application to the description of heterogeneous freezing of mineral dust-like particles with soluble coatings.

Heavy Metals Speciation in Dust Samples from Various Parts of ...

African Journals Online (AJOL)

Dust on our roads constitutes a major source of environmental hazard. Little attention is paid to the enormous challenges resulting from its polluting effect and health implications. In this investigation, twenty five dust samples were collected from 5 locations within Ebonyi North, South and Central Senatorial Zones between ...

Addition of electric arc furnace dust in hot metal changing the form of addition

International Nuclear Information System (INIS)

Marques Sobrinho, Vicente de Paulo Ferreira; Oliveira, Jose Roberto de; Vieira, Estefano Aparecido; Telles, Victor Bridi; Grillo, Felipe Fardin; Tenorio, Jorge Alberto Soares; Espinosa, Denise Crocce Romano

2014-01-01

This research aims to study the incorporation of the mass of electric arc furnace dust (EAFD), by addition in hot metal (1.78% Si) at a temperature of 1,400 degrees Celsius. The EAFD is from a steel plant producing long steel. The addition of the EAFD was as received, in the form of briquettes without agitation of the hot metal and in the form of briquettes with agitation of the hot metal. Previously, the EAFD was characterized using the following techniques: chemical analysis, size analysis, X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) microanalysis. The achievement of fusion experiments in laboratory scale, took place in a vertical tubular furnace with temperature control. The fusion experiments to assess the incorporation of EAFD mass used graphite crucibles. After cooling, the hot metal and the slag, remaining in the crucible, were weighed to do a mass balance. A flow of inert gas (argon) was maintained inside the furnace during the experiments. Results show that the experiment with addition of EAFD as received presents the best result of incorporating the mass of the final hot metal (1.73%) combined with the lowest percentage of volatilized mass of EAFD (46.52%). The experiment addition of EAFD in the form of briquette with agitation of hot metal presents the lowest percentage of slag mass (4.58%). The zinc content of volatilized EAFD (64.30%) is higher than the zinc content of the imported ore concentrate (52%) and zinc content of the national ore concentrate (12% to 39%). The presence of lead and cadmium in the slag characterizing it as a hazardous solid waste. (author)

Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies with LEGUS

Science.gov (United States)

Kahre, L.; Walterbos, R. A.; Kim, H.; Thilker, D.; Calzetti, D.; Lee, J. C.; Sabbi, E.; Ubeda, L.; Aloisi, A.; Cignoni, M.; Cook, D. O.; Dale, D. A.; Elmegreen, B. G.; Elmegreen, D. M.; Fumagalli, M.; Gallagher, J. S., III; Gouliermis, D. A.; Grasha, K.; Grebel, E. K.; Hunter, D. A.; Sacchi, E.; Smith, L. J.; Tosi, M.; Adamo, A.; Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.; Chandar, R.; Christian, C.; de Mink, S. E.; Dobbs, C.; Evans, A. S.; Herrero, A.; Johnson, K. E.; Kennicutt, R. C.; Krumholz, M. R.; Messa, M.; Nair, P.; Nota, A.; Pellerin, A.; Ryon, J. E.; Schaerer, D.; Shabani, F.; Van Dyk, S. D.; Whitmore, B. C.; Wofford, A.

2018-03-01

We present a study of the dust-to-gas ratios in five nearby galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I), and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury program Legacy ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced Camera for Surveys data, we correct thousands of individual stars for extinction across these five galaxies using an isochrone-matching (reddening-free Q) method. We generate extinction maps for each galaxy from the individual stellar extinctions using both adaptive and fixed resolution techniques and correlate these maps with neutral H I and CO gas maps from the literature, including the H I Nearby Galaxy Survey and the HERA CO-Line Extragalactic Survey. We calculate dust-to-gas ratios and investigate variations in the dust-to-gas ratio with galaxy metallicity. We find a power-law relationship between dust-to-gas ratio and metallicity, consistent with other studies of dust-to-gas ratio compared to metallicity. We find a change in the relation when H2 is not included. This implies that underestimation of {N}{{{H}}2} in low-metallicity dwarfs from a too-low CO-to-H2 conversion factor X CO could have produced too low a slope in the derived relationship between dust-to-gas ratio and metallicity. We also compare our extinctions to those derived from fitting the spectral energy distribution (SED) using the Bayesian Extinction and Stellar Tool for NGC 7793 and find systematically lower extinctions from SED fitting as compared to isochrone matching.

Sequential extraction of heavy metals from urban dust and street sediments. Pt. 1. Sequential extraction of heavy metals in micro samples; Sequentielle Schwermetallextraktion aus Staubniederschlaegen und Strassensedimenten. T. 1. Sequentielle Schwermetallextraktion von Mikroproben

Energy Technology Data Exchange (ETDEWEB)

Heiser, U.; Norra, S.; Stueben, D.; Wagner, M. von [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Petrographie und Geochemie

1999-01-01

For the application of sequential extraction of heavy metals from samples that can only be obtained in amounts of a few milligrams (micro samples, e.g. airborne dust fallout), the method after Zeien and Bruemmer (1989) was progressed. A down scale to 1:100 was carried out and the accuracy of this method with variable sample amounts of about 20 mg and an extraction volume of 500 {mu}l was proofed with standard soil samples. The influence of variable extraction ratios (ratio of sample amount and volume of extraction solvent) and the influence of intensive treatment of dust sampled by the Bergerhoff-method (VDI 2119/2, 1972) prior sequential extraction, was within the precision of measurement of our method. Thus, we showed that sequential extraction can be applied for the investigation of heavy metal mobilization in micro samples with variable sample amounts. A first application of our method for microsamples was carried out to investigate airborne dust fallout and street sediments at two urban sites where different heavy metal immission rates due to traffic influence occur. These investigations will be presented in part 2 (`Sequential extraxction of heavy metals from urban dust`). (orig.) [Deutsch] Fuer die Anwendung der sequentiellen Schwermetallextraktion auf Proben, die nur im Milligramm-Bereich erhalten werden koennen (Mikroproben, wie z.B. Staubniederschlaege), wurde die Methode von Zeien und Bruemmer (1989) weiterentwickelt. Der Extraktionsmassstab wurde um den Faktor 1:100 verringert und die Reproduzierbarkeit des Verfahrens mit variablen Probenmengen um 20 mg und einem Extraktionsvolumen von 500 {mu}l mit Hilfe von Standardboeden nachgewiesen. Moegliche Einfluesse variabler Extraktionsverhaeltnisse (Verhaeltnis von Probenmenge zu Extraktionsvolumen) sowie eine aufwendige Vorbehandlung von Staubproben, die nach der Bergerhoff-Methode (VDI 2119/2, 1972) gesammelt wurden, lagen bei diesen Untersuchungen weitgehend im Variationsbereich des Verfahrens. Die

The observation of dust behavior in TRIAM-1M

International Nuclear Information System (INIS)

Sasaki, K.; Hanada, K.; Nishino, N.; Tokitani, M.; Yoshida, N.; Sato, K.N.; Zushi, H.; Nakamura, K.; Sakamoto, M.; Idei, H.; Hasegawa, M.; Kawasaki, S.; Nakasihma, H.; Higashijima, A.

2007-01-01

The observation of dusts in plasmas was carried out by high speed camera in full non-inductive lower hybrid current drive (LHCD) plasma on TRIAM-1M. The velocities of dusts were 10-50 m/s. The number of dust generated per second increased with the discharge duration in the range of 20-57 s. This suggests that a part of dusts were generated from a movable limiter whose the surface temperature increases with the discharge duration. Dusts were coming from various directions even close to the movable limiter. Dusts were collected in the vacuum vessel by use of a kind of cleaner and the composition and the size of dust were examined by Scanning Electron Microscope (SEM). Dust size was several μm and composition was Molybdenum mixed with small amount of elements of stainless metal. The poloidal distribution of the collected mass of dusts was almost uniform

Dust Acoustic Solitons in the Dusty Plasma of the Earth's Ionosphere

International Nuclear Information System (INIS)

Kopnin, S.I.; Kosarev, I.N.; Popel, S.I.; Yu, M.Y.

2005-01-01

Stratified structures that are observed at heights of 80-95 km in the lower part of the Earth's ionosphere are known as noctilucent clouds and polar mesosphere summer echoes. These structures are thought to be associated with the presence of vast amounts of charged dust or aerosols. The layers in the lower ionosphere where there are substantial amounts of dust are called the dusty ionosphere. The dust grains can carry a positive or a negative charge, depending on their constituent materials. As a rule, the grains are ice crystals, which may contain metallic inclusions. A grain with a sufficiently large metallic content can acquire a positive charge. Crystals of pure ice are charged negatively. The distribution of the dust grains over their charges has a profound impact on the ionizational and other properties of dust structures in the dusty ionosphere. In the present paper, a study is made of the effect of the sign of the dust charge on the properties of dust acoustic solitons propagating in the dusty ionosphere. It is shown that, when the dust charge is positive, dust acoustic solitons correspond to a hill in the electron density and a well in the ion density. When the dust is charged negatively, the situation is opposite. These differences in the properties of dust acoustic solitons can be used to diagnose the plasmas of noctilucent clouds and polar mesosphere summer echoes

Characterization of electric arc furnace dust aiming reuse

International Nuclear Information System (INIS)

Grillo, F.F.; Oliveira, E.B.G.; Oliveira, J.R. de; Telles, V.B.; Tenorio, J.A.S.

2010-01-01

This work aims to study the characterize of steelmaking dust, from the primary refining of steel in Electric Arc Furnace, in order to verify feasibility of reuse through the addition of hot metal in the form of briquette. The techniques used to characterize the dust was chemical analyses, size separation tests, X-ray diffraction analyses (XRD), Scanning Electron Microscopy (SEM). After characterization, was the calculation of reductant considering the complete reduction of iron oxides and then to briquetting. The waste sample is composed essentially of spherical particles and has a very small particle size (85% below 10 μm). The XRD has presented compounds such as ZnFe 2 O 4 , Fe 3 O 4 , ZnO e SiO 2 . This work showed that its possible recovery approximately 92% of metal iron from dust generated during steelmaking.This (author)

Physico-Chemical and Environmental Characterisation of the Dust from Dry Dedusting of the Green Sand

Directory of Open Access Journals (Sweden)

Bobrowski A.

2016-12-01

Full Text Available The article presents research results of physico-chemical and environmental issues for the dust generated during dedusting of the installation for the processing and preparation of moulding sand with bentonite. Particular attention was paid to the content of heavy metals and emission of gases from the BTEX group, which is one of the determinants of the moulding sands harmfulness for the environment. The analysis of heavy metals in the test samples indicate that there is an increase of the content of all metals in the dust compared to the initial mixture of bentonite. The most significant (almost double increase observed for zinc is probably related to the adsorption of this element on the dust surface by contact with the liquid metal. The study showed, that dust contained more than 20% of the amount of montmorillonite and had a loss on ignition at a similar level. The addition of 1% of dust to the used moulding sand results in almost 30% increase in the total volume of gases generated in casting processes and nearly 30% increase of the benzene emission.

Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia

Energy Technology Data Exchange (ETDEWEB)

Gunawardena, Janaka, E-mail: j.gunawardena@qut.edu.au; Ziyath, Abdul M., E-mail: mohamed.ziyath@qut.edu.au; Bostrom, Thor E., E-mail: t.bostrom@qut.edu.au; Bekessy, Lambert K., E-mail: l.bekessy@qut.edu.au; Ayoko, Godwin A., E-mail: g.ayoko@qut.edu.au; Egodawatta, Prasanna, E-mail: p.egodawatta@qut.edu.au; Goonetilleke, Ashantha, E-mail: a.goonetilleke@qut.edu.au

2013-09-01

The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. - Highlights: • The dust storm contributed a large fraction of fine particles to pollutant build-up. • The dust storm increased TSS, Al, Fe and Mn loads in build-up on ground surfaces. • Dust storm did not significantly increase TOC, Ni, Cu, Pb and Cd loads in build-up. • Cr and Zn in dust storm deposition were contributed by local anthropogenic sources.

Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia

International Nuclear Information System (INIS)

Gunawardena, Janaka; Ziyath, Abdul M.; Bostrom, Thor E.; Bekessy, Lambert K.; Ayoko, Godwin A.; Egodawatta, Prasanna; Goonetilleke, Ashantha

2013-01-01

The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. - Highlights: • The dust storm contributed a large fraction of fine particles to pollutant build-up. • The dust storm increased TSS, Al, Fe and Mn loads in build-up on ground surfaces. • Dust storm did not significantly increase TOC, Ni, Cu, Pb and Cd loads in build-up. • Cr and Zn in dust storm deposition were contributed by local anthropogenic sources

Dust Fertilization of the Western Atlantic Biota: a Biochemical Model

Science.gov (United States)

Holmes, C. W.

2017-12-01

Every year an estimated 50 million tons of African dust reaches the Western Atlantic. This dust is composed of quartz sand, clay, and a mixture of quartz and clay particles agglutinated with micronutrient enriched ferruginous cement. However, whether it is friend or foe to biochemical systems is a matter of conjecture. Corals are ideal recorders of changing conditions as the layers can be dated so that the record of chemical changes is easily assessed. There is extensive shallow-and deep water coral development bordering the Florida Straits. The changes in trace element chemistry within these corals show a positive relationship with the African dust record. Recently, it has been demonstrated that many of the metals contained within the dust are necessary micronutrients in the fertilization of plankton. Using the results of these studies, a biochemical model has been constructed. This model suggests a path from inorganic dust through microbial transformation to micronutrient enzymes (i.e. Cd-enriched carbonic anahydrase) and carbonate precipitation on the Bahamian Banks. It is estimated that more than ten million metric tons of this fine, metal-rich sediment is formed each year. However, for much of this sediment, its deposition is temporary, as it is transported into the Florida Straits yearly by tropical cyclones. This metal-enriched fine carbonate becomes nutrients for phytoplankton, providing food for the corals, both shallow and deep.

Removal of Heavy Metal Ions by Using Composite of Cement Kiln Dust/Ethylene Glycol co Acrylic Acid Prepared by y-Irradiation

International Nuclear Information System (INIS)

Sokker, H.H.; Abdel-Rahman, H.A.; Khattab, M.M.; Ismail, M.R.

2010-01-01

Various composites of cement kiln dust (CKD) and poly(ethylene glycol co acrylic acid) using y-irradiation was investigated. The samples were prepared using three percentages of cement kiln dust namely, 20, 50 and 75 by wt % and mixed with an equimolar ratio (1:1) of ethylene glycol and acrylic acid then irradiated at doses; 10,20 and 30 kGy of gamma-irradiation. The results showed that (CKD) and poly(ethylene glycol co acrylic acid) composites were formed only at 30 kGy. In addition, CKD alone has the lowest degree of removal of heavy metal ions compared with the prepared composites. A composite containing 75% cement kiln dust by weight percentage, showed the highest degree of removal of cobalt ions, whereas, a composite of 20% CKD showed the highest degree for cadmium ion removal. While the composite of 75% CKD showed a higher selectivity of cobalt ion than cadmium ion in their mixed solution.

Gas and dust from solar metallicity AGB stars

Science.gov (United States)

Ventura, P.; Karakas, A.; Dell'Agli, F.; García-Hernández, D. A.; Guzman-Ramirez, L.

2018-04-01

We study the asymptotic giant branch (AGB) evolution of stars with masses between 1 M⊙and8.5 M⊙. We focus on stars with a solar chemical composition, which allows us to interpret evolved stars in the Galaxy. We present a detailed comparison with models of the same chemistry, calculated with a different evolution code and based on a different set of physical assumptions. We find that stars of mass ≥3.5 M⊙ experience hot bottom burning at the base of the envelope. They have AGB lifetimes shorter than ˜3 × 105 yr and eject into their surroundings gas contaminated by proton-capture nucleosynthesis, at an extent sensitive to the treatment of convection. Low-mass stars with 1.5 M⊙ ≤ M ≤ 3 M⊙ become carbon stars. During the final phases, the C/O ratio grows to ˜3. We find a remarkable agreement between the two codes for the low-mass models and conclude that predictions for the physical and chemical properties of these stars, and the AGB lifetime, are not that sensitive to the modelling of the AGB phase. The dust produced is also dependent on the mass: low-mass stars produce mainly solid carbon and silicon carbide dust, whereas higher mass stars produce silicates and alumina dust. Possible future observations potentially able to add more robustness to the present results are also discussed.

Recycling of steelmaking dusts: The Radust concept

Directory of Open Access Journals (Sweden)

Jalkanen H.

2005-01-01

Full Text Available Recycling of dusts and other wastes of steelmaking is becoming to a necessity of two reasons: due to high contents of iron oxides dusts are valuable raw material for steelmaking and tightening environmental legislation makes the landfill disposal of wastes more expensive. Fine dust fractions from various stages of steelmaking route contain besides iron and carbon heavy metals especially zinc and lead and heavy hydrocarbons that are acceptable neither for landfill disposal nor for recycling back to processes without any spe4cial treatments. Some theoretical and practical aspects concerning high temperature treatments of steelmaking dusts for removal of hazardous components and production of clean high iron raw material for recycling is discussed in this paper. The Radust technology developed at Koverhar steelwork in Finland for treatment of the most problematic fine fractions of blast furnace and oxygen converter dusts is shortly presented and discussed.

Levels of house dust mite allergen in cars.

Science.gov (United States)

Mason, Howard J; Smith, Ian; Anua, Siti Marwanis; Tagiyeva, Nargiz; Semple, Sean; Devereux, Graham

2015-09-01

This small study investigated house dust mite (HDM) allergen levels in cars and their owners' homes in north-east Scotland. Dust samples from twelve households and cars were collected in a standardised manner. The dust samples were extracted and measured for the Dermatophagoides group 2 allergens (Der p 2 and Der f 2) and total soluble protein. Allergen levels at homes tended to be higher than in the cars, but not significantly. However, they significantly correlated with paired car dust samples expressed either per unit weight of dust or soluble protein (rho=0.657; p=0.02 and 0.769; p=0.003, respectively). This points to house-to-car allergen transfer, with the car allergen levels largely reflecting levels in the owner's home. Car HDM allergen levels were lower than those reported in Brazil and the USA. Twenty-five percent of the houses and none of the cars had allergen levels in dust greater than 2000 ng g(-1). This value is often quoted as a threshold for the risk of sensitisation, although a number of studies report increased risk of sensitisation at lower levels. This small study does not allow for characterisation of the distribution of HDM allergen in vehicles in this geographic area, or of the likely levels in other warmer and more humid areas of the UK. Cars and other vehicles are an under-investigated micro-environment for exposure to allergenic material.

Hydrometallurgical treatment of copper smelter dusts. Desarsenification of leaching solutions

International Nuclear Information System (INIS)

Alguacil, F.J.; Magne, L.; Navarro, P.; Simpson, J.

1996-01-01

Copper smelter dusts contain along with this metal, which is amenable for its recovery, a number of other metals (especially arsenic) which are considered as toxic. Different alternatives have been proposed for the treatment of such metallurgical residues and among them Hydrometallurgy shows good perspectives for its application in this field. In the present work different hydrometallurgical processes proposed for the treatment of copper smelter dusts are described and evaluated together with different alternatives given for the Desarsenification of the leaching solutions. (Author) 36 refs

Magnetic, geochemical characterization and health risk assessment of road dust in Xuanwei and Fuyuan, China.

Science.gov (United States)

Tan, Zhengying; Lu, Senlin; Zhao, Hui; Kai, Xiao; Jiaxian, Peng; Win, Myat Sandar; Yu, Shang; Yonemochi, Shinich; Wang, Qingyue

2018-01-19

As an accumulation of solid organic and inorganic pollutant particles on outdoor ground surfaces, road dust is an important carrier of heavy metal contaminants and can be a valuable medium for characterizing urban environmental quality. Because the dusts can be an important source of atmospheric particles and take impact on human health, the aim of this study described in detail the mineralogical characteristics, morphology, and heavy metal content of road dust from Xuanwei and Fuyuan, locations with high lung cancer incidence. Our results show that the average concentrations of heavy metals in road dust were higher than their background values. Higher concentrations of heavy metals were found in the magnetic fractions (MFs) than in the non-magnetic fractions (NMFs). Magnetic measurements revealed high magnetic susceptibility values in the road dust samples, and the dominant magnetic carrier was magnetite. The magnetic grains were predominantly pseudo-single domain, multi-domain, and coarse-grained stable single domains (coarse SSD) in size. SEM/XRD analysis identified two groups of magnetic particles: spherules and angular/aggregate particles. Hazard index (HI) values for adults exposure to road dust samples, including MF, Bulk, and NMF, in both areas were lower or close to safe levels, while HI values for childhood exposure to magnetic fractions in both areas were very close or higher than safe levels. Cancer risks from road dust exposure in both areas were in the acceptable value range.

Development of dust removal system using static electricity for fusion experimental reactors

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Masanori; Ueda, Yasutoshi; Oda, Yasushi; Takahashi, Kenji [Mitsubishi Heavy Industries Ltd., Tokyo (Japan); Seki, Yasushi; Aoki, Isao; Ueda, Shuzo; Kurihara, Ryoichi

1997-11-01

Tests to collect and transport metallic and non-metallic dust particles have been conducted using static electricity in a vacuum environment to investigate the applicability of a static electricity dust removal system for fusion experimental reactors. The dust particles are charged by electrostatic induction, floated and collected due to the Coulomb force generated by the AC electric field. They are then transported due to the gradient force induced by the electric curtain of the non-uniform travelling-wave electric field. Using a fully insulated electrode with a single-phase AC voltage up to 15 kV, aluminum and carbon dust were successfully collected. The highest collection rates for the aluminum and carbon dust were around 30 and 2 g/min, respectively. The linear-type electrodes, using as high as 22 kV of the three-phase AC voltage, transported aluminum dust up to an angle of 60deg. Applying a guide electrode to the linear-type electrode, the transportation rate was approximately doubled and almost constant at every angle, including a 90deg angle. The system transported aluminum dust up to the rate of 13 g/min. The influence of the 0.15 T magnetic field on the dust collection and transportation efficiencies was found to be negligible. (author)

Development of dust removal system using static electricity for fusion experimental reactors

International Nuclear Information System (INIS)

Onozuka, Masanori; Ueda, Yasutoshi; Oda, Yasushi; Takahashi, Kenji; Seki, Yasushi; Aoki, Isao; Ueda, Shuzo; Kurihara, Ryoichi.

1997-01-01

Tests to collect and transport metallic and non-metallic dust particles have been conducted using static electricity in a vacuum environment to investigate the applicability of a static electricity dust removal system for fusion experimental reactors. The dust particles are charged by electrostatic induction, floated and collected due to the Coulomb force generated by the AC electric field. They are then transported due to the gradient force induced by the electric curtain of the non-uniform travelling-wave electric field. Using a fully insulated electrode with a single-phase AC voltage up to 15 kV, aluminum and carbon dust were successfully collected. The highest collection rates for the aluminum and carbon dust were around 30 and 2 g/min, respectively. The linear-type electrodes, using as high as 22 kV of the three-phase AC voltage, transported aluminum dust up to an angle of 60deg. Applying a guide electrode to the linear-type electrode, the transportation rate was approximately doubled and almost constant at every angle, including a 90deg angle. The system transported aluminum dust up to the rate of 13 g/min. The influence of the 0.15 T magnetic field on the dust collection and transportation efficiencies was found to be negligible. (author)

Dust Evolution in Galaxy Cluster Simulations

Science.gov (United States)

Gjergo, Eda; Granato, Gian Luigi; Murante, Giuseppe; Ragone-Figueroa, Cinthia; Tornatore, Luca; Borgani, Stefano

2018-06-01

We implement a state-of-the-art treatment of the processes affecting the production and Interstellar Medium (ISM) evolution of carbonaceous and silicate dust grains within SPH simulations. We trace the dust grain size distribution by means of a two-size approximation. We test our method on zoom-in simulations of four massive (M200 ≥ 3 × 1014M⊙) galaxy clusters. We predict that during the early stages of assembly of the cluster at z ≳ 3, where the star formation activity is at its maximum in our simulations, the proto-cluster regions are rich in dusty gas. Compared to the case in which only dust production in stellar ejecta is active, if we include processes occurring in the cold ISM,the dust content is enhanced by a factor 2 - 3. However, the dust properties in this stage turn out to be significantly different from those observationally derived for the average Milky Way dust, and commonly adopted in calculations of dust reprocessing. We show that these differences may have a strong impact on the predicted spectral energy distributions. At low redshift in star forming regions our model reproduces reasonably well the trend of dust abundances over metallicity as observed in local galaxies. However we under-produce by a factor of 2 to 3 the total dust content of clusters estimated observationally at low redshift, z ≲ 0.5 using IRAS, Planck and Herschel satellites data. This discrepancy does not subsist by assuming a lower sputtering efficiency, which erodes dust grains in the hot Intracluster Medium (ICM).

Elemental Concentration of Harmattan Dust Sample in Iwo and Oyo ...

African Journals Online (AJOL)

ADOWIE PERE

According to Balogun (1979), two sources of dust plumes were identified .... metals. Heavy metals are known to be harmful to human health if they are more than the recommended ... Chemical. Characterization and Source Apportionment of.

Peach leaf responses to soil and cement dust pollution.

Science.gov (United States)

Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

2015-10-01

Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

Elastic–plastic adhesive impacts of tungsten dust with metal surfaces in plasma environments

NARCIS (Netherlands)

Ratynskaia, S.; Tolias, P.; Shalpegin, A.; Vignitchouk, L.; de Angeli, M.; I. Bykov,; Bystrov, K.; Bardin, S.; Brochard, F.; Ripamonti, D.; N. den Harder,; De Temmerman, G.

2015-01-01

Dust-surface collisions impose size selectivity on the ability of dust grains to migrate in scrape-off layer and divertor plasmas and to adhere to plasma-facing components. Here, we report first experimental evidence of dust impact phenomena in plasma environments concerning low-speed collisions of

Potential human exposure to halogenated flame-retardants in elevated surface dust and floor dust in an academic environment

International Nuclear Information System (INIS)

Allgood, Jaime M.; Jimah, Tamara; McClaskey, Carolyn M.; La Guardia, Mark J.; Hammel, Stephanie C.; Zeineddine, Maryam M.; Tang, Ian W.; Runnerstrom, Miryha G.; Ogunseitan, Oladele A.

2017-01-01

Most households and workplaces all over the world possess furnishings and electronics, all of which contain potentially toxic flame retardant chemicals to prevent fire hazards. Indoor dust is a recognized repository of these types of chemicals including polybrominated diphenyl ethers (PBDEs) and non-polybrominated diphenyl ethers (non-PBDEs). However, no previous U.S. studies have differentiated concentrations from elevated surface dust (ESD) and floor dust (FD) within and across microenvironments. We address this information gap by measuring twenty-two flame-retardant chemicals in dust on elevated surfaces (ESD; n=10) and floors (FD; n=10) from rooms on a California campus that contain various concentrations of electronic products. We hypothesized a difference in chemical concentrations in ESD and FD. Secondarily, we examined whether or not this difference persisted: (a) across the studied microenvironments and (b) in rooms with various concentrations of electronics. A Wilcoxon signed-rank test demonstrated that the ESD was statistically significantly higher than FD for BDE-47 (p=0.01), BDE-99 (p=0.01), BDE-100 (p=0.01), BDE-153 (p=0.02), BDE-154 (p=0.02), and 3 non-PBDEs including EH-TBB (p=0.02), BEH-TEBP (p=0.05), and TDCIPP (p=0.03). These results suggest different levels and kinds of exposures to flame-retardant chemicals for individuals spending time in the sampled locations depending on the position of accumulated dust. Therefore, further research is needed to estimate human exposure to flame retardant chemicals based on how much time and where in the room individuals spend their time. Such sub-location estimates will likely differ from assessments that assume continuous unidimensional exposure, with implications for improved understanding of potential health impacts of flame retardant chemicals. - Highlights: • Brominated flame retardants used in electronic products accumulate in room dust • Various chemical moieties of flame retardants leach

Potential human exposure to halogenated flame-retardants in elevated surface dust and floor dust in an academic environment

Energy Technology Data Exchange (ETDEWEB)

Allgood, Jaime M.; Jimah, Tamara [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States); McClaskey, Carolyn M. [Department of Cognitive Sciences, School of Social Sciences, University of California, Irvine, CA 92697-5100 (United States); La Guardia, Mark J. [Department of Aquatic Health Sciences, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 (United States); Hammel, Stephanie C.; Zeineddine, Maryam M.; Tang, Ian W.; Runnerstrom, Miryha G. [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States); Ogunseitan, Oladele A., E-mail: Oladele.Ogunseitan@uci.edu [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States)

2017-02-15

Most households and workplaces all over the world possess furnishings and electronics, all of which contain potentially toxic flame retardant chemicals to prevent fire hazards. Indoor dust is a recognized repository of these types of chemicals including polybrominated diphenyl ethers (PBDEs) and non-polybrominated diphenyl ethers (non-PBDEs). However, no previous U.S. studies have differentiated concentrations from elevated surface dust (ESD) and floor dust (FD) within and across microenvironments. We address this information gap by measuring twenty-two flame-retardant chemicals in dust on elevated surfaces (ESD; n=10) and floors (FD; n=10) from rooms on a California campus that contain various concentrations of electronic products. We hypothesized a difference in chemical concentrations in ESD and FD. Secondarily, we examined whether or not this difference persisted: (a) across the studied microenvironments and (b) in rooms with various concentrations of electronics. A Wilcoxon signed-rank test demonstrated that the ESD was statistically significantly higher than FD for BDE-47 (p=0.01), BDE-99 (p=0.01), BDE-100 (p=0.01), BDE-153 (p=0.02), BDE-154 (p=0.02), and 3 non-PBDEs including EH-TBB (p=0.02), BEH-TEBP (p=0.05), and TDCIPP (p=0.03). These results suggest different levels and kinds of exposures to flame-retardant chemicals for individuals spending time in the sampled locations depending on the position of accumulated dust. Therefore, further research is needed to estimate human exposure to flame retardant chemicals based on how much time and where in the room individuals spend their time. Such sub-location estimates will likely differ from assessments that assume continuous unidimensional exposure, with implications for improved understanding of potential health impacts of flame retardant chemicals. - Highlights: • Brominated flame retardants used in electronic products accumulate in room dust • Various chemical moieties of flame retardants leach

Status of metal levels and their potential sources of contamination in Southeast Asian rivers.

Science.gov (United States)

Chanpiwat, Penradee; Sthiannopkao, Suthipong

2014-01-01

To assess the concentration and status of metal contaminants in four major Southeast Asian river systems, water were collected from the Tonle Sap-Bassac Rivers (Cambodia), Citarum River (Indonesia), lower Chao Phraya River (Thailand), and Saigon River (Vietnam) in both dry and wet seasons. The target elements were Be, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Ba, Tl, and Pb and the concentrations exceeded the background metal concentrations by 1- to 88-fold. This distinctly indicates enrichment by human urban area activities. The results of a normalization technique used to distinguish natural from enriched metal concentrations confirmed contamination by Al, Cd, Co, Mn, Ni, Pb, and Zn. Cluster analysis revealed the probable source of metals contamination in most sampling sites on all rivers studied to be anthropogenic, including industrial, commercial, and residential activities. Stable lead isotopes analyses applied to track the sources and pathways of anthropogenic lead furthermore confirmed that anthropogenic sources of metal contaminated these rivers. Discharges of wastewater from both industrial and household activities were major contributors of Pb into the rivers. Non-point sources, especially road runoff and street dust, also contributed contamination from Pb and other metals.

Development of an unsteady model for the investigation of the thermal instability of pulverulent solid mixtures - Application to metallic dust deposits

International Nuclear Information System (INIS)

Bideau, David

2010-01-01

The first part of this research thesis proposes a synthesis of knowledge on phenomena related to the self-heating behaviour of metallic dusts, more particularly in the case of thin layers and deposits. A quick presentation of the dust explosion phenomenon allows the introduction of the ignition of thin layers which leaded in the past to several thermal explosion steady models which are herein presented. A preliminary study is then reported which aimed at selecting materials of interest with a maximum difference of ignition sensitivity (i.e. ignition temperature). Some characterizations of these thus selected materials are presented, notably the kinetic study of fuel dust oxidation reactions. Reaction kinetics and associated parameters (activation energy, frequency factors) are then determined. In a third part, an unsteady model is developed. In order to validate the computation code, experimental tests are performed on binary mixtures with different contents: isothermal tests for the measurement of the minimum ignition temperature, dynamic tests to measure the ignition temperature with respect to a heating ramp. Simulation results are compared with experimental results

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-03-01

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

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

International Nuclear Information System (INIS)

Abbasi, Golnoush; Saini, Amandeep; Goosey, Emma; Diamond, Miriam L.

2016-01-01

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

problems in spinning in kolfe house-hold utencil factory abstract ...

African Journals Online (AJOL)

Kolfe House-Hold Utensil Factory in Addis Ababa, is producing different types of utensils for house-hold use from commercial aluminium. Deep drawing or/and spinning are the methods used for shaping this metal to desired shape and size, though some small parts are cast too. One of their products is kettle, which is.

Soil or Dust for Health Risk Assessment Studies in Urban Environment.

Science.gov (United States)

Gabarrón, M; Faz, A; Acosta, J A

2017-10-01

To identify the best material (soil or dust) to be selected for health-risk assessment studies, road dust and urban soil from three cities with different population densities were collected, and size fractions were analysed for metal content (Pb, Zn, Cu, Cd, Cr, Co, and Ni). Results showed similar distribution of the size particles among cities, predominating fractions between 75 and 2000 μm in road dust and particles below 75 μm in soil. Metals were mainly bound to PM10 in both soil and road dust increasing the risk of adverse health effects, overall through inhalation exposure. The risk assessment showed that the most hazardous exposure pathway was the ingestion via, followed by dermal absorption and inhalation route. Values of hazard quotient showed that the risk for children due to the ingestion and dermal absorption was higher than adults, and slightly larger at PM10 comparing to <75-μm fraction for the inhalation route. Higher risk values were found for road dust, although any hazard index or cancer risk index value did not overreach the safe value of 10 -6 .

Laser-induced mobilization of dust produced during fusion reactors operation

International Nuclear Information System (INIS)

Vatry, A.

2010-01-01

During tokamak operation, plasma-wall interactions lead to material erosion process and dusts production. These dusts are mainly composed by carbon and tungsten, with sizes ranging from 10 nm to 100 μm. For safety reasons and to guarantee an optimum reactor functioning, the dusts have to be kept in reasonable quantity. The dusts mobilization is a first step to collect them, and the laser is a promising technique for this application. To optimize the cleaning, physical mechanisms responsible for dust ejection induced by laser have been identified. Some particles, such as aggregates, are directly ablated by the laser. The metal droplets are ejected intact by an electrostatic force, induced by the photoelectrons. We also characterized the particles ejection to choose an appropriate collection device. (author) [fr

Contamination of Soil, Water, Plant and Dust by Zinc, Lead and Cadmium in Southwest Isfahan

Directory of Open Access Journals (Sweden)

Nastaran Esmaeilpourfard

2016-02-01

Full Text Available Introduction Due to mining, considerable amounts of heavy metal bearing mineralsare scattered in the atmosphere in the form of dust and make the surrounding air, water and soils polluted.Runoff water movingfrom the mountainstowardsplains may also transport heavy metals from mines to the soils.One type ofpollutions is contamination withheavy metals.The purpose of the present research has been to investigate the effect of heavy metals of mine on soil, water, plant and dust pollution. Materials and Methods: Gushfil mine is located 3 kilometers southwest of Sepahanshahr, Isfahan. Soil profiles were dug 500 meters apart along three parallel transects, between east of Sepahanshahr and Gushfil mine. The profiles were described and samples were collected from their horizons. Ore, wells, plant and dust were sampled as well. Total concentrations of lead, zinc and cadmium were measured in the samples. To find the origin of polluted dust and soil, lead isotopes contents in the samples were measured and regressional relationships between the ratios of these contents were investigated. Results and Discussion Sepahanshahr soils are not contaminated by zinc, lead and cadmium, but within a distance of one to two kilometers from the Gushfil mine, the soils are polluted by zinc and lead. Cadmium contamination was not observed in the studied soils. In all of the soils, the heavy metals content varies downwards irregularly. The reason for this variation trend is that the studied soils are alluvial. In different periods of time, alluvium parent materials have been transported by runoff water from the lead and zinc mines towards the alluvial piedmont plain. The studied heavy metals have been distributed irregularly in different horizons of the soils that have been formed in these parent materials. Lead and cadmium concentrations of drinking water in the studied area are much higher than the maximum amount allowed by the World Health Organization. Cadmium content in

A PUBLIC CATALOG OF STELLAR MASSES, STAR FORMATION AND METALLICITY HISTORIES, AND DUST CONTENT FROM THE SLOAN DIGITAL SKY SURVEY USING VESPA

International Nuclear Information System (INIS)

Tojeiro, Rita; Wilkins, Stephen; Heavens, Alan F.; Panter, Ben; Jimenez, Raul

2009-01-01

We applied the VESPA algorithm to the Sloan Digital Sky Survey final data release of the Main Galaxies and Luminous Red Galaxies samples. The result is a catalog of stellar masses, detailed star formation and metallicity histories and dust content of nearly 800,000 galaxies. We make the catalog public via a T-SQL database, which is described in detail in this paper. We present the results using a range of stellar population and dust models, and will continue to update the catalog as new and improved models are made public. We also present a brief exploration of the catalog, and show that the quantities derived are robust: luminous red galaxies can be described by one to three populations, whereas a main galaxy sample galaxy needs on average two to five; red galaxies are older and less dusty; the dust values we recover are well correlated with measured Balmer decrements and star formation rates are also in agreement with previous measurements. We find that whereas some derived quantities are robust to the choice of modelling, many are still not.

Alkaline phosphatase activity in the subtropical ocean: insights from nutrient, dust and trace metal addition experiments

Directory of Open Access Journals (Sweden)

Claire eMahaffey

2014-12-01

Full Text Available Phosphorus is an essential nutrient for all life on earth. In the ocean, the most bioavailable form of phosphorus is inorganic phosphate, but in the extensive subtropical gyres, phosphate concentrations can be chronically low and limit primary productivity and nitrogen fixation. In these regions, organisms produce hydrolytic enzymes, such as alkaline phosphatase (AP, that enable them to utilize the more replete dissolved organic phosphorus (DOP pool to meet their cellular phosphorus demands. In this study, we synthesized data from 14 published studies and present our own findings from two research cruises (D326 and D361 in the eastern subtropical Atlantic to explore the relationship between AP activity (APA and nutrients, Saharan dust and trace metals. We found that below a threshold phosphate concentration of ~ 30 nM, APA increased with an inverse hyperbolic relationship with phosphate concentration. Meanwhile, DOP concentrations decreased with enhanced APA, indicating utilization of the DOP pool. We found APA rates were significantly higher in the subtropical Atlantic compared to the subtropical Pacific Ocean, even over the same low phosphate concentration range (0 to 50 nM. While the phosphate concentration may have a first order control on the APA rates, we speculate that other factors influence this basin scale contrast. Using bioassay experiments, we show that the addition of Saharan dust and zinc significantly increased the rate of APA. To our knowledge, our results are the first direct field-based evidence that APA is limited by zinc in the subtropical ocean. Further work is required to explore the relationship between trace metals such as iron and zinc, which are co-factors of phosphohydrolytic enzymes, specifically PhoX and PhoA, respectively, and APA in the ocean.

House dust in seven Danish offices

Science.gov (United States)

Mølhave, L.; Schneider, T.; Kjærgaard, S. K.; Larsen, L.; Norn, S.; Jørgensen, O.

Floor dust from Danish offices was collected and analyzed. The dust was to be used in an exposure experiment. The dust was analyzed to show the composition of the dust which can be a source of airborne dust indoors. About 11 kg of dust from vacuum cleaner bags from seven Danish office buildings with about 1047 occupants (12 751 m 2) was processed according to a standardized procedure yielding 5.5 kg of processed bulk dust. The bulk dust contained 130.000-160.000 CFU g -1 microorganisms and 71.000-90.000 CFU g -1 microfungi. The content of culturable microfungi was 65-123 CFU 30 g -1 dust. The content of endotoxins ranged from 5.06-7.24 EU g -1 (1.45 ng g -1 to 1.01 ng g -1). Allergens (ng g -1) were from 147-159 (Mite), 395-746 (dog) and 103-330 (cat). The macro molecular organic compounds (the MOD-content) varied from 7.8-9.8 mg g -1. The threshold of release of histamine from basophil leukocytes provoked by the bulk dust was between 0.3 and 1.0 mg ml -1. The water content was 2% (WGT) and the organic fraction 33%. 6.5-5.9% (dry) was water soluble. The fiber content was less than 0.2-1.5% (WGT) and the desorbable VOCs was 176-319 μg g -1. Most of the VOC were aldehydes. However, softeners for plastic (DBP and DEHP) were present. The chemical composition includes human and animal skin fragments, paper fibers, glass wool, wood and textilefibers and inorganic and metal particles. The sizes ranged from 0.001-1 mm and the average specific density was 1.0 g m -3. The bulk dust was resuspended and injected into an exposure chamber. The airborne dust was sampled and analyzed to illustrate the exposures that can result from sedimented dirt and dust. The airborne dust resulting from the bulk dust reached concentrations ranging from 0.26-0.75 mg m -3 in average contained 300-170 CFU m -3. The organic fraction was from 55-70% and the water content about 2.5% (WGT). The content of the dust was compared to the similar results reported in the literature and its toxic potency is

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

Science.gov (United States)

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

Effect of recycling blast furnace flue dust as pellets on the sintering performance

Directory of Open Access Journals (Sweden)

El-Hussiny N.A.

2010-01-01

Full Text Available The Egyptian Iron and Steel Company generates a great amount of blast furnace flue dust. The recovery of metals and carbon from this flue dust becomes a very important demand due to the increase of the price of coke breeze and the decrease of the primary source of metals. At the same time, it make the environment more safe by decreasing pollution. Introducing these dust fines in the sintering process proves to be very harmful for different operating parameters. Thus, this study aims at investigating the production of pellets resulting from these fines, using molasses as organic binder and its application in sintering of iron ore. The sintering experiments were performed using flue dust as pellets as a substitute of coke breeze. The results revealed that, sintering properties such as inter strength increases with using the flue dust pellets, while productivity of both the sinter machine and sinter machine at blast furnace yard decreases. Also the vertical velocity of the sinter machine and the weight loss during the reduction of produced the sinter by hydrogen decrease.

Metals recovery of spent household batteries using a hydrometallurgical process; Recuperacao de metais de sucatas de pilhas e baterias pos-consumo utilizando processamento hidrometalurgico

Energy Technology Data Exchange (ETDEWEB)

Souza, K.P.; Tenorio, J.A.S., E-mail: kprovazi@gmail.co [Universidade de Sao Paulo (USP), SP (Brazil). Dept. de Engenharia Metalurgica e de Materiais

2010-07-01

The objective of the work is to study a method for metals recovery from a sample composed by a mixture of the main types of spent household batteries. Segregation of the main metals is investigated using a treatment route consisting of the following steps: manual identified and dismantling, grinding, electric furnace reduction, acid leaching and selective precipitation with sodium hydroxide with and without hydrogen peroxide. Before and after precipitations the solutions had been analyzed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP/OES) and the precipitated analyzed by Scanning Electron Microscopy (SEM) with Spectrometry of Energy Dispersion Spectroscopy (EDS). The results had indicated that the great majority of metals had been precipitated in pHs studied, also had co-precipitation or simultaneous precipitation of metals in some pHs. (author)

Dust from Zambian smelters: mineralogy and contaminant bioaccessibility

Czech Academy of Sciences Publication Activity Database

Ettler, V.; Vítková, M.; Mihaljevič, M.; Šebek, O.; Klementová, Mariana; Veselovský, F.; Vybíral, P.; Kříbek, B.

2014-01-01

Roč. 36, č. 5 (2014), s. 919-933 ISSN 0269-4042 Institutional support: RVO:61388980 Keywords : Dust * Metal smelting * Copper * Cobalt * Solid speciation Subject RIV: CA - Inorganic Chemistry Impact factor: 2.566, year: 2014

Some stars are totally metal: a new mechanism driving dust across star-forming clouds, and consequences for planets, stars, and galaxies

International Nuclear Information System (INIS)

Hopkins, Philip F.

2014-01-01

Dust grains in neutral gas behave as aerodynamic particles, so they can develop large local density fluctuations entirely independent of gas density fluctuations. Specifically, gas turbulence can drive order-of-magnitude 'resonant' fluctuations in the dust density on scales where the gas stopping/drag timescale is comparable to the turbulent eddy turnover time. Here we show that for large grains (size ≳ 0.1 μm, containing most grain mass) in sufficiently large molecular clouds (radii ≳ 1-10 pc, masses ≳ 10 4 M ☉ ), this scale becomes larger than the characteristic sizes of prestellar cores (the sonic length), so large fluctuations in the dust-to-gas ratio are imprinted on cores. As a result, star clusters and protostellar disks formed in large clouds should exhibit significant abundance spreads in the elements preferentially found in large grains (C, O). This naturally predicts populations of carbon-enhanced stars, certain highly unusual stellar populations observed in nearby open clusters, and may explain the 'UV upturn' in early-type galaxies. It will also dramatically change planet formation in the resulting protostellar disks, by preferentially 'seeding' disks with an enhancement in large carbonaceous or silicate grains. The relevant threshold for this behavior scales simply with cloud densities and temperatures, making straightforward predictions for clusters in starbursts and high-redshift galaxies. Because of the selective sorting by size, this process is not necessarily visible in extinction mapping. We also predict the shape of the abundance distribution—when these fluctuations occur, a small fraction of the cores may actually be seeded with abundances Z ∼ 100 (Z) such that they are almost 'totally metal' (Z ∼ 1)! Assuming the cores collapse, these totally metal stars would be rare (1 in ∼10 4 in clusters where this occurs), but represent a fundamentally new stellar evolution channel.

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

Science.gov (United States)

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

2013-11-01

A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution. Copyright © 2013 Elsevier Ltd. All rights reserved.

House dust as possible route of environmental exposure to cadmium and lead in the adult general population

International Nuclear Information System (INIS)

Hogervorst, Janneke; Plusquin, Michelle; Vangronsveld, Jaco; Nawrot, Tim; Cuypers, Ann; Van Hecke, Etienne; Roels, Harry A.; Carleer, Robert; Staessen, Jan A.

2007-01-01

Contaminated soil particles and food are established routes of exposure. We investigated the relations between biomarkers of exposure to cadmium and lead, and the metal loading rates in house dust in the adult residents of an area with a soil cadmium concentration of >=3mg/kg (n=268) and a reference area (n=205). We determined the metal concentrations in house dust allowed to settle for 3 months in Petri dishes placed in the participants' bedrooms. The continuously distributed vegetable index was the first principal component derived from the metal concentrations in six different vegetables. The biomarkers of exposure (blood cadmium 9.2 vs. 6.2nmol/L; 24-h urinary cadmium 10.5 vs. 7.0nmol; blood lead 0.31 vs. 0.24μmol/L), the loading rates of cadmium and lead in house dust (0.29 vs. 0.12 and 7.52 vs. 3.62ng/cm 2 /92 days), and the vegetable indexes (0.31 vs. -0.44 and 0.13 vs. -0.29 standardized units) were significantly higher in the contaminated area. A two-fold increase in the metal loading rate in house dust was associated with increases (P<0.001) in blood cadmium (+2.3%), 24-h urinary cadmium (+3.0%), and blood lead (+2.0%), independent of the vegetable index and other covariates. The estimated effect sizes on the biomarkers of internal exposure were three times greater for house dust than vegetables. In conclusion, in the adult population, house dust is potentially an important route of exposure to heavy metals in areas with contaminated soils, and should be incorporated in the assessment of health risks

Household batteries: Evaluation of collection methods

Energy Technology Data Exchange (ETDEWEB)

Seeberger, D.A.

1992-12-31

While it is difficult to prove that a specific material is causing contamination in a landfill, tests have been conducted at waste-to-energy facilities that indicate that household batteries contribute significant amounts of heavy metals to both air emissions and ash residue. Hennepin County, MN, used a dual approach for developing and implementing a special household battery collection. Alternative collection methods were examined; test collections were conducted. The second phase examined operating and disposal policy issues. This report describes the results of the grant project, moving from a broad examination of the construction and content of batteries, to a description of the pilot collection programs, and ending with a discussion of variables affecting the cost and operation of a comprehensive battery collection program. Three out-of-state companies (PA, NY) were found that accept spent batteries; difficulties in reclaiming household batteries are discussed.

Household batteries: Evaluation of collection methods

Energy Technology Data Exchange (ETDEWEB)

Seeberger, D.A.

1992-01-01

While it is difficult to prove that a specific material is causing contamination in a landfill, tests have been conducted at waste-to-energy facilities that indicate that household batteries contribute significant amounts of heavy metals to both air emissions and ash residue. Hennepin County, MN, used a dual approach for developing and implementing a special household battery collection. Alternative collection methods were examined; test collections were conducted. The second phase examined operating and disposal policy issues. This report describes the results of the grant project, moving from a broad examination of the construction and content of batteries, to a description of the pilot collection programs, and ending with a discussion of variables affecting the cost and operation of a comprehensive battery collection program. Three out-of-state companies (PA, NY) were found that accept spent batteries; difficulties in reclaiming household batteries are discussed.

Chromatography Of Metal Ions On Wood Cellulose Impregnated ...

African Journals Online (AJOL)

Adsorption chromatography of some heavy metal ions on wood cellulose of saw dust (wood waste dust) modified with hydrochloric acid, urea and thiourea was studied. Atomic absorption spectrophotometry (AAS) was used to determine the initial concentration of solutions of Zn2+, Cu2+, Ni2+, Pb2+, and Fe3+ metal ions.

House dust-mite allergen exposure is associated with serum specific IgE but not with respiratory outcomes.

Science.gov (United States)

Bakolis, I; Heinrich, J; Zock, J P; Norbäck, D; Svanes, C; Chen, C M; Accordini, S; Verlato, G; Olivieri, M; Jarvis, D

2015-06-01

Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunologic response to dust-mite allergens in those who are IgE sensitized to house dust-mite. Mattress house dust-mite concentrations were measured in a population-based sample of 2890 adults aged between 27 and 56 years living in 22 centers in 10 countries. Generalized linear mixed models were employed to explore the association of respiratory symptoms with house dust-mite concentrations, adjusting for individual and household confounders. There was no overall association of respiratory outcomes with measured house dust-mite concentrations, even in those who reported they had symptoms on exposure to dust and those who had physician-diagnosed asthma. However, there was a positive association of high serum specific IgE levels to HDM (>3.5 kUA /l) with mattress house dust-mite concentrations and a negative association of sensitization to cat with increasing house dust-mite concentrations. In conclusion, there was no evidence that respiratory symptoms in adults were associated with exposure to house dust-mite allergen in the mattress, but an association of house mite with strong sensitization was observed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Dust Emission at 8 and 24 μ m as Diagnostics of H ii Region Radiative Transfer

Energy Technology Data Exchange (ETDEWEB)

Oey, M. S.; López-Hernández, J.; Kellar, J. A. [Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Avenue, Ann Arbor, MI, 48109-1107 (United States); Pellegrini, E. W. [Institut für Theoretische Astrophysik, Albert-Überle-Str. 2, D-69120 Heidelberg (Germany); Gordon, K. D.; Meixner, M.; Roman-Duval, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Jameson, K. E. [Astronomy Department and Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Li, A. [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Madden, S. C. [Laboratoire AIM, CEA, Université Paris VII, IRFU/Service d’Astrophysique, Bat. 709, F-91191 Gif-sur-Yvette (France); Bot, C. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 Rue de l’Université, F-67000 Strasbourg (France); Rubio, M. [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300RA Leiden (Netherlands)

2017-07-20

We use the Spitzer Surveying the Agents of Galaxy Evolution (SAGE) survey of the Magellanic Clouds to evaluate the relationship between the 8 μ m polycyclic aromatic hydrocarbon (PAH) emission, 24 μ m hot dust emission, and H ii region radiative transfer. We confirm that in the higher-metallicity Large Magellanic Cloud, PAH destruction is sensitive to optically thin conditions in the nebular Lyman continuum: objects identified as optically thin candidates based on nebular ionization structure show six times lower median 8 μ m surface brightness (0.18 mJy arcsec{sup −2}) than their optically thick counterparts (1.2 mJy arcsec{sup −2}). The 24 μ m surface brightness also shows a factor of three offset between the two classes of objects (0.13 versus 0.44 mJy arcsec{sup −2}, respectively), which is driven by the association between the very small dust grains and higher density gas found at higher nebular optical depths. In contrast, PAH and dust formation in the low-metallicity Small Magellanic Cloud is strongly inhibited such that we find no variation in either 8 μ m or 24 μ m emission between our optically thick and thin samples. This is attributable to extremely low PAH and dust production together with high, corrosive UV photon fluxes in this low-metallicity environment. The dust mass surface densities and gas-to-dust ratios determined from dust maps using Herschel HERITAGE survey data support this interpretation.

Lead dust in broken hill homes--a potential hazard for young children?

Science.gov (United States)

Boreland, F; Lyle, D M; Wlodarczyk, J; Balding, W A; Reddan, S

2002-01-01

To determine the potential hazard posed by indoor lead dust to young children in Broken Hill, a silver-lead-zinc mining town in outback Australia, and the degree to which lead flux is influenced by factors such as geographical location, house construction type and condition. 116 homes were selected and 93 (80%) studied from 10 localities in Broken Hill during the spring of 1995. Lead flux was measured using 85 mm diameter polystyrene petri dishes. Dishes were placed in four rooms of each house to collect dust over a six-to-eight-week period. Data on the location, condition and construction type of each house were recorded. Multiple linear regression was used to determine predictors of lead flux. Flux data were log transformed for the analysis. Average household lead flux varied nearly seven-fold across districts from a low of 166 (distant from the mines), to a high of 1,104 microg/m2/30-day period (adjacent to the mines). Houses that were 'adequately sealed' had 2.9 times the lead flux, and 'poorly sealed' houses 4.3 times the flux, of 'very well sealed' houses. Construction material did not significantly affect these flux levels, and no statistically significant interactions were found between house condition and location or house type. Many Broken Hill homes have high levels of lead flux that pose a potential risk to young children. Quantification of this hazard provides useful information for the community that can help focus efforts on actions required to minimise lead dust in the home. Household dust is a potential source of lead for young children in at-risk communities. Information on lead flux in homes can assist these communities and public health agencies to better understand and deal more effectively with the problem.

Metal Exposure and Associated Health Risk to Human Beings by Street Dust in a Heavily Industrialized City of Hunan Province, Central China

Directory of Open Access Journals (Sweden)

Guangyi Sun

2017-03-01

Full Text Available Fifty-five urban street dust samples were collected from Zhuzhou, an industrial city in central China and analyzed for a range of toxic elements. Potential carcinogenic and non-carcinogenic health effects on children and adults due to exposure to street dust were assessed. Concerning the two subgroups, the child cohort is confronted with considerably greater health risks than adults. According to the Hazard Quotient (HQ method, ingestion of dust particles poses primary risk to children and adults, followed by dermal contact and inhalation for all of the metals investigated except Hg, for which inhalation of its elemental vapor constitute a slightly higher risk than ingestion. For children, Pb, As, Cd, Cr, Hg and Sb exposure were deemed as the highest contributors to non-cancer health risks, while As and Cr represent an enhanced cancer risk for children. For adults, risk indicator values for both cancer and non-cancer effects obtained were within the safety threshold. In a comparison with other locations within and outside mainland China, exposure to arsenic is prominent for the population of Zhuzhou, indicating more attention and preventive actions should been taken.

Comparative Analysis of Household Waste Composition in the Different Districts of Stockholm

OpenAIRE

Miafodzyeva, Sviatlana; Brandt, Nils

2011-01-01

Separating household waste into fractions at the place where it was generated is one of the most popular methods of collection household waste in most European countries. In 1994 a producer responsibility ordinance for packaging was introduced in Sweden. This ordinance mandates householders to sort out packaging waste, clean the waste and sort different package materials – paper, plastic, glass and metal in assigned recycling bins. Household’s participation is mandatory but in practice it is ...

Survey the environmental effects of the household batteries on decreasing of compost quality

International Nuclear Information System (INIS)

Davari, A.; Sharifan, Hamid Reza

2008-01-01

The household batteries consisted the heavy metals are one of the important pollutant for Environment. whereas Iran has no environmental policy for them and without environmental planning they input to urban waste solid so this study has surveyed effect of the household batteries in urban waste solid to decreasing of compost quality that produced in Karaj composting. For this research has sampled of compost production then analyzed for assess the heavy metal. In the laboratory the samples were grind then hair sieve to convert them to similar pieces. For the measuring metal concentration first they should be extract and finally measure by adsorption atomic spectroscope. The result show high concentration of heavy metal such as Ni, Cd, Zn, Hg, etc. that there were in produced compost. So major cause of law quality of this compost refer to concentration of heavy metals. Findings were in contrary to standard concentration for agriculture soil. It's obvious the heavy metals concentration depend to quantity of consumption the kinds of batteries

Lunar Dust Mitigation Screens

Science.gov (United States)

Knutson, Shawn; Holloway, Nancy

being developed in a collaborative effort between Langley Research Center and Kennedy Space Center. The screens typically consist of spiral shaped conductive traces patterned on high dielectric substrates (i.e. glass, quartz, polyimide film, etc.). Two broad categories of substrate materials are being investigated for the screens. One category consists of transparent substrates (i.e. glass, quartz, sapphire, etc.), and the other non-transparent sub-strates (Kapton, polyimide films, metals, etc.). The transparent screens utilize patterns made from indium tin oxide (ITO), a transparent conductive material, on clear substrates while the non-transparent screens use copper patterns on a transluscent or opaque substrates. Further, the screen is coated with a high dielectric polyimide cover layer to protect the screen pattern. One promising cover layer material that is currently being investigated is Langley Research Center-Soluble Imide (LaRC-SI), a NASA LaRC developed polyimide. Lastly, a top-coat of hard, inorganic material is evaporated onto the cover layer for protection from scratches due to abrasive nature of the dust. Of note, several top-coat materials are under investigation and include: aluminum oxide, silicon dioxide, titanium oxide, yttrium oxide, zirconium oxide, and zinc sulfide. The electrostatic dust mitigation screens function when a high voltage (700V or greater) is applied to the screen electrodes, thus creating an electromagnetic wave across the surface of the screen that repels the dust. Lunar dust typically contains a high positive charge; therefore, the screens are charged with a higher positive charge that effectively repels dust from the surface (i.e. like charges repel, unlike charges attract). It is anticipated that full development and maturation of this technology will enable humans to sustain a long term presence on the moon, and other planets where dust may have negative implications.

Thermodynamic analysis of the selective chlorination of electric arc furnace dust

International Nuclear Information System (INIS)

Pickles, C.A.

2009-01-01

The remelting of automobile scrap in an electric arc furnace (EAF) results in the production of a dust, which contains high concentrations of the oxides of zinc, iron, calcium and other metals. Typically, the lead and zinc are of commercial value, while the other metals are not worth recovering. At the present time, EAF dusts are treated in high temperature Waelz rotary kiln-type processes, where the lead and zinc oxides are selectively reduced and simultaneously reoxidized and a crude zinc oxide is produced. Another alternative processing route is selective chlorination, in which the non-ferrous metals are preferentially chlorinated to their gaseous chlorides and in this manner separated from the iron. In the present research, a detailed thermodynamic analysis of this chlorination process has been performed and the following factors were investigated; temperature, amount of chlorine, lime content, silica content, presence of an inert gas and the oxygen potential. High lead and zinc recoveries as gaseous chlorides could be achieved but some of the iron oxide was also chlorinated. Additionally, the calcium oxide in the dust consumes chlorine, but this can be minimized by adding silica, which results in the formation of stable calcium silicates. The optimum conditions were determined for a typical dust composition. The selectivities achieved with chlorination were lower than those for reduction, as reported in the literature, but there are other advantages such as the potential recovery of copper.

Thermodynamic analysis of the selective chlorination of electric arc furnace dust

Energy Technology Data Exchange (ETDEWEB)

Pickles, C.A., E-mail: pickles-c@mine.queensu.ca [Department of Mining Engineering, Queen' s University, Kingston, Ontario, K7L 3N6 (Canada)

2009-07-30

The remelting of automobile scrap in an electric arc furnace (EAF) results in the production of a dust, which contains high concentrations of the oxides of zinc, iron, calcium and other metals. Typically, the lead and zinc are of commercial value, while the other metals are not worth recovering. At the present time, EAF dusts are treated in high temperature Waelz rotary kiln-type processes, where the lead and zinc oxides are selectively reduced and simultaneously reoxidized and a crude zinc oxide is produced. Another alternative processing route is selective chlorination, in which the non-ferrous metals are preferentially chlorinated to their gaseous chlorides and in this manner separated from the iron. In the present research, a detailed thermodynamic analysis of this chlorination process has been performed and the following factors were investigated; temperature, amount of chlorine, lime content, silica content, presence of an inert gas and the oxygen potential. High lead and zinc recoveries as gaseous chlorides could be achieved but some of the iron oxide was also chlorinated. Additionally, the calcium oxide in the dust consumes chlorine, but this can be minimized by adding silica, which results in the formation of stable calcium silicates. The optimum conditions were determined for a typical dust composition. The selectivities achieved with chlorination were lower than those for reduction, as reported in the literature, but there are other advantages such as the potential recovery of copper.

Thermodynamic analysis of the selective chlorination of electric arc furnace dust.

Science.gov (United States)

Pickles, C A

2009-07-30

The remelting of automobile scrap in an electric arc furnace (EAF) results in the production of a dust, which contains high concentrations of the oxides of zinc, iron, calcium and other metals. Typically, the lead and zinc are of commercial value, while the other metals are not worth recovering. At the present time, EAF dusts are treated in high temperature Waelz rotary kiln-type processes, where the lead and zinc oxides are selectively reduced and simultaneously reoxidized and a crude zinc oxide is produced. Another alternative processing route is selective chlorination, in which the non-ferrous metals are preferentially chlorinated to their gaseous chlorides and in this manner separated from the iron. In the present research, a detailed thermodynamic analysis of this chlorination process has been performed and the following factors were investigated; temperature, amount of chlorine, lime content, silica content, presence of an inert gas and the oxygen potential. High lead and zinc recoveries as gaseous chlorides could be achieved but some of the iron oxide was also chlorinated. Additionally, the calcium oxide in the dust consumes chlorine, but this can be minimized by adding silica, which results in the formation of stable calcium silicates. The optimum conditions were determined for a typical dust composition. The selectivities achieved with chlorination were lower than those for reduction, as reported in the literature, but there are other advantages such as the potential recovery of copper.

Occurrence and distribution of heavy metals in indoor settled ...

African Journals Online (AJOL)

The results showed widespread heavy metals contamination especially Fe and Zn, which were present as the highest concentration while Cd was the lowest in the settled particles (dust). The order of occurrence of heavy metals in settled particles (dust) collected indoor in 2007 and 2008 respectively were as follows, ...

Assessment of dust exposure in a steel plant in the eastern coast of peninsular Malaysia.

Science.gov (United States)

Nurul, Ainun Hamzah; Shamsul, Bahri Mohd Tamrin; Noor Hassim, Ismail

2016-11-22

Steel manufacturing produces dust, fumes, and pollutant gases that may give adverse health effects to the respiratory function of workers. Improper occupational hygiene practice in the workplace will affect both workers wellbeing and productivity. To assess the level of particulate matter [(PM2.5, PM10, and Total Particulate Matter (TPM)], and trace metal dust concentrations in different sections of a steel plant and compare with the occupational exposure values. The work environmental parameters of the particulate matters were evaluated using Indoor Air Quality, while metal dust concentrations were measured using portable personal air sampler. A total of 184 personal samples were randomly collected from workers in three major sections; steel making plant, direct reduced plant, and support group. Trace metal dust concentrations were subjected to wet mineral acid mixture digestion and analysed by atomic absorption spectrophotometer (AAS). The overall average PM2.5 concentration observed was varied according to the section: steel making plant was 0.18 mg/m3, direct reduced iron plant was 0.05 mg/m3, and support plant was 0.05 mg/m3. Average PM 10 concentration in steel making shop (SMS) plant, direct reduced (DR) plant, and support plant were 0.70 mg/m3, 0.84 mg/m3, and 0.58 mg/m3, respectively. The average TWA8 of trace metal dusts (cobalt and chromium) in all the sections exceeded 1 to 3 times the ACGIH prescribed values, OSHA PELs, NIOSH RELs as well as USECHH OSHA, whereas TWA8 concentration of nickel for each section did not exceed the occupational exposure values. The average PM2.5, PM10 and TPM did not exceed the prescribed values, while average trace metal dust concentration TWA8 for cobalt and chromium in all plants exceeded occupational exposure prescribed values. However, the nickel found did not exceed the prescribed values in all the plants except for NIOSH RELs.

Exposure to phthalates in house dust and associated allergies in children aged 6-12years.

Science.gov (United States)

Ait Bamai, Yu; Araki, Atsuko; Kawai, Toshio; Tsuboi, Tazuru; Saito, Ikue; Yoshioka, Eiji; Cong, Shi; Kishi, Reiko

2016-11-01

Phthalates are widely used as plasticizers in household products. Several studies have reported an association between phthalate exposure and an increased risk of allergies. The present study estimated phthalate exposure in children aged 6-12years and assessed potential correlations with allergies. House dust samples were collected from floors and multi-surface objects >35cm above the floor. Urine samples were collected from the first morning void of the day. Daily phthalate intake (DI dust and DI) was estimated using both house dust and urinary metabolite concentrations. Exposure to di-2-ethylhexyl phthalate (DEHP) in floor dust was associated with parental-reported rhino-conjunctivitis. After stratification by gender, this trend was found to only occur in boys. Furthermore, urinary mono-isobutyl phthalate was inversely associated with parental-reported wheeze in boys. DI dust of benzyl butyl phthalate (BBzP) and DEHP were significantly correlated with DI_BBzP and DI_DEHP, respectively. These correlations were stronger with floor than with multi-surface dust. Our results suggest that, among Japanese children, house dust from low surfaces, such as living room floors, might play a meaningful role in the indoor environmental exposure pathway for BBzP and DEHP. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Origin of Dust in the Early Universe: Probing the Star Formation History of Galaxies by Their Dust Content

Science.gov (United States)

Dwek, Eli; Cherchneff, Isabelle

2010-01-01

Two distinct scenarios for the origin of the approximately 4 x 10(exp 8) Solar Mass of dust observed in the high-redshift (z = 6.4) quasar J1148+5251 have been proposed. The first assumes that this galaxy is much younger than the age of the universe at that epoch so that only supernovae, could have produced this dust. The second scenario assumes a significantly older galactic age, so that the dust could have formed in lower-mass AGB stars. Presenting new integral solutions for the chemical evolution of metals and dust in galaxies, we offer a critical evaluation of these two scenarios. ^N;"(,, show that the AGB scenario is sensitive to the details of the galaxy's star formation history (SFH), which must consist of an early intense starburst followed by a period of low stellar activity. The presence or absence of massive amounts of dust in high-redshift galaxies can therefore be used to infer their SFH. However, a problem with the AGB scenario is that it produces a stellar mass that is significantly larger than the inferred dynamical mass of J1148+5251, an yet unresolved discrepancy. If this problem persists, then additional sites for the growth or formation of dust, such as molecular clouds or dense clouds around active galactic nuclei, must be considered.

Emission of Metals from Pelletized and Uncompressed Biomass Fuels Combustion in Rural Household Stoves in China

Science.gov (United States)

Zhang, Wei; Tong, Yindong; Wang, Huanhuan; Chen, Long; Ou, Langbo; Wang, Xuejun; Liu, Guohua; Zhu, Yan

2014-07-01

Effort of reducing CO2 emissions in developing countries may require an increasing utilization of biomass fuels. Biomass pellets seem well-suited for residential biomass markets. However, there is limited quantitative information on pollutant emissions from biomass pellets burning, especially those measured in real applications. In this study, biomass pellets and raw biomass fuels were burned in a pellet burner and a conventional stove respectively, in rural households, and metal emissions were determined. Results showed that the emission factors (EFs) ranged 3.20-5.57 (Pb), 5.20-7.58 (Cu), 0.11-0.23 (Cd), 12.67-39.00 (As), 0.59-1.31 mg/kg (Ni) for pellets, and 0.73-1.34 (Pb), 0.92-4.48 (Cu), 0.08-0.14 (Cd), 7.29-13.22 (As), 0.28-0.62 (Ni) mg/kg for raw biomass. For unit energy delivered to cooking vessels, the EFs ranged 0.42-0.77 (Pb), 0.79-1.16 (Cu), 0.01-0.03 (Cd), 1.93-5.09 (As), 0.08-0.19 mg/MJ (Ni) for pellets, and 0.30-0.56 (Pb), 0.41-1.86 (Cu), 0.04-0.06 (Cd), 3.25-5.49 (As), 0.12-0.26 (Ni) mg/MJ for raw biomass. This study found that moisture, volatile matter and modified combustion efficiency were the important factors affecting metal emissions. Comparisons of the mass-based and task-based EFs found that biomass pellets produced higher metal emissions than the same amount of raw biomass. However, metal emissions from pellets were not higher in terms of unit energy delivered.

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

Science.gov (United States)

Plane, John M. C.; Flynn, George J.; Määttänen, Anni; Moores, John E.; Poppe, Andrew R.; Carrillo-Sanchez, Juan Diego; Listowski, Constantino

2018-02-01

Recent advances in interplanetary dust modelling provide much improved estimates of the fluxes of cosmic dust particles into planetary (and lunar) atmospheres throughout the solar system. Combining the dust particle size and velocity distributions with new chemical ablation models enables the injection rates of individual elements to be predicted as a function of location and time. This information is essential for understanding a variety of atmospheric impacts, including: the formation of layers of metal atoms and ions; meteoric smoke particles and ice cloud nucleation; perturbations to atmospheric gas-phase chemistry; and the effects of the surface deposition of micrometeorites and cosmic spherules. There is discussion of impacts on all the planets, as well as on Pluto, Triton and Titan.

Endotoxin, coliform, and dust levels in various types of rodent bedding.

Science.gov (United States)

Whiteside, Tanya E; Thigpen, Julius E; Kissling, Grace E; Grant, Mary G; Forsythe, Diane

2010-03-01

Endotoxins in grain dust, household dust, and animal bedding may induce respiratory symptoms in rodents and humans. We assayed the endotoxin, coliform, and dust levels in 20 types of rodent bedding. Endotoxin concentrations were measured by using a commercial test kit, coliform counts were determined by using conventional microbiologic procedures, and dust content was evaluated by using a rotating-tapping shaker. Paper bedding types contained significantly less endotoxin than did other bedding types; the highest levels of endotoxin were detected in hardwood and corncob beddings. The range of endotoxin content for each bedding type was: corncob bedding, 1913 to 4504 endotoxin units per gram (EU/g); hardwood bedding, 3121 to 5401 EU/g; corncob-paper mixed bedding, 1586 to 2416 EU/g; and paper bedding, less than 5 to 105 EU/g. Coliform counts varied from less than 10 to 7591 cfu/g in corncob beddings, 90 to 4010 cfu/g in corncob-paper mixed beddings, less than 10 to 137 cfu/g in hardwood beddings, and less than 10 cfu/g in paper beddings. Average dust content was less than 0.15% in all commercial bedding types. We conclude that paper bedding is the optimal bedding type for conducting LPS inhalation studies and that rodent bedding containing high levels of endotoxin may alter the results of respiratory and immunologic studies in rodents.

Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

International Nuclear Information System (INIS)

Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

2012-01-01

Highlights: ► Analytical method for PGEs, main group, transition and rare earth metals developed. ► Comprehensive characterization of road and tunnel dust samples was accomplished. ► PGEs in dusts arise from autocatalyst attrition. ► Mobile sources also contributed to Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. ► All other elements, including rare earths arose from crustal sources. - Abstract: Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g −1 respectively in tunnel dusts while they varied between 6 and 8 ng g −1 , 10 and 88 ng g −1 and 35 and 131 ng g −1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However

Paleo-dust insights onto dust-climate interactions

Science.gov (United States)

Albani, S.; Mahowald, N. M.

2017-12-01

Mineral dust emissions are affected by changing climate conditions, and in turn dust impacts the atmospheric radiation budget, clouds and biogeochemical cycles. Climate and public health dust-related issues call for attention on the fate of the dust cycle in the future, and the representation of the dust cycle is now part of the strategy of the Paleoclimate Modelling Intercomparison Project phase 4 and the Coupled Model Intercomparison Project phase 6 (PMIP4-CMIP6). Since mineral aerosols are one of the most important natural aerosols, understanding past dust responses to climate in the paleoclimate will allow us to better understand mineral aerosol feedbacks with climate and biogeochemistry in the Anthropocene. Modern observations and paleoclimate records offer the possibility of multiple, complementary views on the global dust cycle, and allow to validate and/or constrain the numerical representation of dust in climate and Earth system models. We present our results from a set of simulations with the Community Earth System Model for different climate states, including present and past climates such as the pre-industrial, the mid-Holocene and the Last Glacial Maximum. A set of simulations including a prognostic dust cycle was thoroughly compared with a wide set of present day observations from different platforms and regions, in order to realistically constrain the magnitude of dust load, surface concentration, deposition, optical properties, and particle size distributions. The magnitude of emissions for past climate regimes was constrained based on compilations of paleodust mass accumulation rates and size distributions, as well as based on information on dust provenance. The comparison with a parallel set of simulations without dust allows estimating the impacts of dust on surface climate. We analyze impacts of dust on the mean and variability of surface temperature and precipitation in each climate state, as well as the impacts that changing dust emissions had

Respirable dust measured downwind during rock dust application.

Science.gov (United States)

Harris, M L; Organiscak, J; Klima, S; Perera, I E

2017-05-01

The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.

Dust in High-Redshift Galaxies

Science.gov (United States)

Pettini, Max; King, David L.; Smith, Linda J.; Hunstead, Richard W.

1997-03-01

Measurements of Zn and Cr abundances in 18 damped Lyα systems (DLAs) at absorption redshifts zabs = 0.692-3.390 (but mostly between zabs ~= 2 and 3) show that metals and dust are much less abundant in high-redshift galaxies than in the Milky Way today. Typically, [Zn/H] ~= -1.2 as Zn tracks Fe closely in Galactic stars of all metallicities and is only lightly depleted onto interstellar grains, we conclude that the overall degree of metal enrichment of damped Lyα galaxies ~13.5 Gyr ago (H0 = 50 km s-1 Mpc-1, q0 = 0.05) was ~1/15 solar. Values of [Cr/Zn] span the range from ~=0 to account correctly, it is possible to misinterpret the clues to early nucleosynthesis provided by nonsolar element ratios.

Test plan for glove box testing with the real-time transuranic dust monitor

International Nuclear Information System (INIS)

Partin, J.K.; Fincke, J.R.

1994-10-01

This test plan describes the objectives, instrumentation, and testing procedures used to prove the feasibility of a real-time transuranic dust monitor (RTDM). The RTDM is under development at the Idaho National Engineering Laboratory (INEL) as a Waste Characterization Technology funded by the Buried Waste Integrated Demonstration Project. The instrument is an in situ monitor that uses optical techniques to establish particle size, particle number density, and mass and species of heavy metal contamination. US Department of Energy orders mandate the assessment of radiological exposure and contamination spread during the remediation of radioactive waste. Of particular concern is heavy metal contamination of dust, both radioactive and nonradioactive. Small particles of metal, particularly the radioactive species, tend to become electrically charged and consequently attach themselves to dust particles. This airborne activated dust is a primary means of contamination transport during remediation activities, and therefore, must be continuously monitored to protect personnel involved in the operations and to control the spread of contamination. If real-time monitoring is not available there is increased likelihood of generating unacceptably high levels of contamination and being forced to shut down costly retrieval operations to decontaminate. A series of experiments are described to determine the optimal experimental design, operational parameters, and levels of detection for the RTDM. Initial screening will be performed using monodisperse particle standards to set parameters and calibrate the instrument. Additional testing will be performed using INEL soil samples spiked with a surrogate, cerium oxide, to prove the design before transporting the apparatus to the Test Reactor Area for testing with plutonium-contaminated dusts

19th century London dust-yards: A case study in closed-loop resource efficiency

International Nuclear Information System (INIS)

Velis, Costas A.; Wilson, David C.; Cheeseman, Christopher R.

2009-01-01

The material recovery methods used by dust-yards in early 19th century London, England and the conditions that led to their development, success and decline are reported. The overall system developed in response to the market value of constituents of municipal waste, and particularly the high coal ash content of household 'dust'. The emergence of lucrative markets for 'soil' and 'breeze' products encouraged dust-contractors to recover effectively 100% of the residual wastes remaining after readily saleable items and materials had been removed by the thriving informal sector. Contracting dust collection to the private sector allowed parishes to keep the streets relatively clean, without the need to develop institutional capacity, and for a period this also generated useful income. The dust-yard system is, therefore, an early example of organised, municipal-wide solid waste management, and also of public-private sector participation. The dust-yard system had been working successfully for more than 50 years before the Public Health Acts of 1848 and 1875, and was thus important in facilitating a relatively smooth transition to an institutionalised, municipally-run solid waste management system in England. The dust-yards can be seen as early precursors of modern materials recycling facilities (MRFs) and mechanical-biological treatment (MBT) plants; however, it must be emphasised that dust-yards operated without any of the environmental and occupational health considerations that are indispensable today. In addition, there are analogies between dust-yards and informal sector recycling systems currently operating in many developing countries

Household hazardous waste in municipal landfills: contaminants in leachate

International Nuclear Information System (INIS)

Slack, R.J.; Gronow, J.R.; Voulvoulis, N.

2005-01-01

Household hazardous waste (HHW) includes waste from a number of household products such as paint, garden pesticides, pharmaceuticals, photographic chemicals, certain detergents, personal care products, fluorescent tubes, waste oil, heavy metal-containing batteries, wood treated with dangerous substances, waste electronic and electrical equipment and discarded CFC-containing equipment. Data on the amounts of HHW discarded are very limited and are hampered by insufficient definitions of what constitutes HHW. Consequently, the risks associated with the disposal of HHW to landfill have not been fully elucidated. This work has focused on the assessment of data concerning the presence of hazardous chemicals in leachates as evidence of the disposal of HHW in municipal landfills. Evidence is sought from a number of sources on the occurrence in landfill leachates of hazardous components (heavy metals and xenobiotic organic compounds [XOC]) from household products and the possible disposal-to-emissions pathways occurring within landfills. This review demonstrates that a broad range of xenobiotic compounds occurring in leachate can be linked to HHW but further work is required to assess whether such compounds pose a risk to the environment and human health as a result of leakage/seepage or through treatment and discharge

Heavy metals in the finest size fractions of road-deposited sediments.

Science.gov (United States)

Lanzerstorfer, Christof

2018-08-01

The concentration of heavy metals in urban road-deposited sediments (RDS) can be used as an indicator for environmental pollution. Thus, their occurrence has been studied in whole road dust samples as well as in size fractions obtained by sieving. Because of the limitations of size separation by sieving little information is available about heavy metal concentrations in the road dust size fractions heavy metals concentrations and size distribution. According to the Geoaccumulation Index the pollution of the road dust samples deceased in the following order: Sb » As > Cu ≈ Zn > Cr > Cd ≈ Pb ≈ Mn > Ni > Co ≈ V. For all heavy metals the concentration was higher in the fine size fractions compared to the coarse size fractions, while the concentration of Sr was size-independent. The enrichment of the heavy metals in the finest size fraction compared to the whole RDS  Sb > (Cu) ≈ Zn ≈ Pb > As ≈ V » Mn. The approximation of the size dependence of the concentration as a function of the particle size by power functions worked very well. The correlation between particle size and concentration was high for all heavy metals. The increased heavy metals concentrations in the finest size fractions should be considered in the evaluation of the contribution of road dust re-suspension to the heavy metal contamination of atmospheric dust. Thereby, power functions can be used to describe the size dependence of the concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of Heavy and Trace Metals in Fingernails of Young ...

African Journals Online (AJOL)

WAHAB

These elements have been produced by alteration and distribution via wind blow. The result indicates that soil or road dust plays an important role in the concentration buildup of the road side dust near automobile workshops. Table 2: Concentration of heavy metals in the soil samples in the automobile workshop. Metals.

Household Income Composition and Household Goods

OpenAIRE

Voynov, Ivan

2005-01-01

The paper focuses on the change in household income composition and the factors that determine it. The results bring additional knowledge about household poverty dynamics. Based on the collective approach to the family and the cooperative game theory it is constructed theoretical model of household income composition change. The change in income composition is a result from bargaining between household members in attempt to defend the most suitable for them income source. Decisive influence i...

42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

Science.gov (United States)

2010-10-01

... mist respirators designed for respiratory protection against fumes of various metals having an air... HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist....1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

DUST DESTRUCTION RATES AND LIFETIMES IN THE MAGELLANIC CLOUDS

International Nuclear Information System (INIS)

Temim, Tea; Dwek, Eli; Boyer, Martha L.; Tchernyshyov, Kirill; Meixner, Margaret; Gall, Christa; Roman-Duval, Julia

2015-01-01

The dust budget in galaxies depends on the rate at which dust grains are created in different stellar sources and destroyed by interstellar shocks. Because of their extensive wavelength coverage, proximity, and nearly face-on geometry, the Magellanic Clouds (MCs) provide a unique opportunity to study these processes in great detail. In this paper, we use the complete sample of supernova remnants (SNRs) in the MCs to calculate the lifetimes and destruction efficiencies of silicate and carbon dust. We find dust lifetimes of 22 ± 13 Myr (30 ± 17 Myr) for silicate (carbon) grains in the LMC, and 54 ± 32 Myr (72 ± 43 Myr) for silicate (carbon) grains in the SMC. The corresponding dust destruction rates are 2.3 × 10 –2 M ☉  yr –1 (5.9 × 10 –3 M ☉  yr –1 ) and 3.0 × 10 –3 M ☉  yr –1 (5.6 × 10 –4 M ☉  yr –1 ) for silicate (carbon) grains in the LMC and SMC, respectively. The significantly shorter lifetimes in the MCs, as compared to the Milky Way, are explained as the combined effect of their lower total dust mass and preferentially higher dust-to-gas (D2G) mass ratios in the vicinity of the SNRs. We find that the maximum dust injection rates by asymptotic giant branch stars and core collapse supernovae are an order of magnitude lower than the dust destruction rates by the SNRs, suggesting that most of the dust may be reconstituted in dense molecular clouds. We also discuss the dependence of the dust destruction rate on the local D2G mass ratio, ambient gas density, and metallicity, as well as the application of our results to other galaxies and dust evolution models

Demonstrating PM2.5 and road-side dust pollution by heavy metals along Thika superhighway in Kenya, sub-Saharan Africa.

Science.gov (United States)

Maina, E G; Gachanja, A N; Gatari, M J; Price, H

2018-03-27

This study assessed the level of heavy metal in roadside dust and PM 2.5 mass concentrations along Thika superhighway in Kenya. Thika superhighway is one of the busiest roads in Kenya, linking Thika town with Nairobi. Triplicate road dust samples collected from 12 locations were analysed for lead (Pb), chromium (Cr), cadmium (Cd), nickel (Ni), zinc (Zn), and copper (Cu) using atomic absorption spectrophotometry (AAS). PM 2.5 samples were collected on pre-weighed Teflon filters using a BGI personal sampler and the filters were then reweighed. The ranges of metal concentrations were 39-101 μg/g for Cu, 95-262 μg/g for Zn, 9-28 μg/g for Cd, 14-24 μg/g for Ni, 13-30 μg/g for Cr, and 20-80 μg/g for Pb. The concentrations of heavy metals were generally highly correlated, indicating a common anthropogenic source of the pollutants. The results showed that the majority of the measured heavy metals were above the background concentration, and in particular, Cd, Pb, and Zn levels indicated moderate to high contamination. Though not directly comparable due to different sampling timeframes (8 h in this study and 24 h for guideline values), PM 2.5 for all sites exceeds the daily WHO PM 2.5 guidelines of 25 μg/m 3 . This poses a health risk to people using and working close to Thika superhighway, for example, local residents, traffic police, street vendors, and people operating small businesses. PM 2.5 levels were higher for sites closer to Nairobi which could be attributed to increased vehicular traffic towards Nairobi from Thika. This study provides some evidence of the air pollution problem arising from vehicular traffic in developing parts of the world and gives an indication of the potential health impacts. It also highlights the need for source apportionment studies to determine contributions of anthropogenic emissions to air pollution, as well as long-term sampling studies that can be used to fully understand spatiotemporal patterns in air pollution

Some stars are totally metal: a new mechanism driving dust across star-forming clouds, and consequences for planets, stars, and galaxies

Energy Technology Data Exchange (ETDEWEB)

Hopkins, Philip F., E-mail: phopkins@caltech.edu [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)

2014-12-10

Dust grains in neutral gas behave as aerodynamic particles, so they can develop large local density fluctuations entirely independent of gas density fluctuations. Specifically, gas turbulence can drive order-of-magnitude 'resonant' fluctuations in the dust density on scales where the gas stopping/drag timescale is comparable to the turbulent eddy turnover time. Here we show that for large grains (size ≳ 0.1 μm, containing most grain mass) in sufficiently large molecular clouds (radii ≳ 1-10 pc, masses ≳ 10{sup 4} M {sub ☉}), this scale becomes larger than the characteristic sizes of prestellar cores (the sonic length), so large fluctuations in the dust-to-gas ratio are imprinted on cores. As a result, star clusters and protostellar disks formed in large clouds should exhibit significant abundance spreads in the elements preferentially found in large grains (C, O). This naturally predicts populations of carbon-enhanced stars, certain highly unusual stellar populations observed in nearby open clusters, and may explain the 'UV upturn' in early-type galaxies. It will also dramatically change planet formation in the resulting protostellar disks, by preferentially 'seeding' disks with an enhancement in large carbonaceous or silicate grains. The relevant threshold for this behavior scales simply with cloud densities and temperatures, making straightforward predictions for clusters in starbursts and high-redshift galaxies. Because of the selective sorting by size, this process is not necessarily visible in extinction mapping. We also predict the shape of the abundance distribution—when these fluctuations occur, a small fraction of the cores may actually be seeded with abundances Z ∼ 100 (Z) such that they are almost 'totally metal' (Z ∼ 1)! Assuming the cores collapse, these totally metal stars would be rare (1 in ∼10{sup 4} in clusters where this occurs), but represent a fundamentally new stellar evolution channel.

Dust Storms from Degraded Drylands of Asia: Dynamics and Health Impacts

Directory of Open Access Journals (Sweden)

Shinji Otani

2017-11-01

Full Text Available Asian dust events are massive meteorological phenomena during which dust particles from Chinese and Mongolian deserts are blown into the atmosphere and carried by westerly winds across Northeast Asia. Recently, there has been steady increase in both the frequency and the severity of Asian atmospheric dust events. Concern has been expressed regarding the potential health hazards in affected areas. The principal nature of the damage associated with Asian dust events differs between the emission (sandstorm and downwind (air pollution regions. In the emission region, the health impacts of dust storms are reflected in the high prevalence of respiratory diseases and severe subjective symptoms. Extreme dust storm events may cause a disaster to happen. In downwind regions such as Japan, analysis of Asian dust particles has shown the presence of ammonium ions, sulfate ions, nitrate ions, and heavy metal compounds that are considered not to originate from soil. Asian dust particles have been thought to adsorb anthropogenic atmospheric pollutants during transport. Therefore, Asian dust events coincide with increases in daily hospital admissions and clinical visits for allergic diseases such as asthma, allergic rhinitis, and conjunctivitis. Although the effect of Asian dust on human health in each region is influenced by a variety of different mechanisms, human activities are partly responsible for such negative effects in many situations. We therefore need to address these environmental problems.

Blast furnace top gas and dusts; Masuunin huippukaasu ja poelyt

Energy Technology Data Exchange (ETDEWEB)

Lohi, T.K.; Mannila, P.; Karjalahti, T.; Haerkki, J.

1997-12-31

This report is related to the `Gas Phase Reactions in a Blast Furnace` project. The aim of the project is to clarify the behaviour of gas phase in a blast furnace with high oil injection rate. The effect of blast furnace operation, iron reduction reactions, the amount of oil injected, alkalis, zinc and sulfur on the formation of top gas and dusts has been examined in this work. In addition, the gas cleaning system, i.e. the dust sack, gas scrubber, venturi scrubbers and an electric filter, of the blast furnaces of Rautaruukki Oy is presented. The composition of the top gas as well as the amount and composition of the dust from the gas cleaners were investigates in the experimental part of the research. The work has been focused on the analysis of carbon, iron, zinc, sulfur and alkalis. In addition to this, possible systematic variations caused by the discharge of hot metal were investigated. The experiments were made at blast furnaces no 1 and 2 of Rautaruukki Raahe Steel. The relationship between dust quantity and composition in the dust sack and the quantity of oil injected was analyzed on the basis of collected data. On the basis of experimental results, hot metal discharge has no effect on the composition or quantity of the top gas and dust. The composition of the dust varied between different gas cleaners. The coarsest and heaviest material remains in the dust sack. The lightest material separates at the electric filter. The main components at every gas cleaner were iron (9.4 - 38.1 %) and carbon (31.5 - 63.7 %). Particles with zinc and sulfur were separated at the venturi scrubbers (Zn = 3.0 % and S = 2.2 %) and the electric filter (Zn = 3.2 % and S = 2.6 %). Particles with alkalis were separated at the end of the gas cleaning process. The amount of sodium at the venturi scrubbers and the electric filter was 1.0 % on average. The average amount of potassium was 0.5 % at the venturi scrubber and 1.4 % at the electric filter 28 refs., 31 figs.

Nonvolatile organic pollutants in domestic dust samples from the urban Hamburg area; Schwerfluechtige organische Umweltchemikalien in Hamburger Hausstaeuben

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-07-01

Nonvolatile organic pollutants were measured in 65 private apartments, i.e. biocides, softeners, flame protection agents, stabilisers, soot, tar and bitumen which are contained in many everyday products and building materials. The homes were the private homes of staff members of the Hamburg Environmental Office and their friends; none of the homes were problem cases. The information was obtained by collecting vacuum cleaner dust. The inhomogeneous dust was screened, and the < 63 {mu}m fraction was analyzed. This fraction was homogeneously enough to provide reproducible results. Chloroparaffins and organic tin compounds were measured for the first time ever in this project. While the concentrations of chloroparaffins were significant, organic tin compounds are rather scarce. Bis(2,ethylhexyl)phthalate (DEHP) was the main component in nearly all household dust samples. Phthalates in general had the highest concentrations. Next to phthalates, chloroparaffins and the biocide permethrin were found in high concentrations, followed by organic phosphates, further biocides, organic tin compounds and benzo(a)pyrene. The individual substances wre assessed on the basis of 95 percent percentiles obtained from the measured frequency distributions. This figure means that 95 percent of the household dust have a lower or equal concentration than the 95 percent percentile. 95 percent percentiles are generally used as reference values in environmental measurements. The reference values presented here should be considered as preliminary values, owing to the fact that the apartments are not representative of the city of Hamburg, and 65 dust samples are too small a data base. Among the most important substances, owing to their high concentrations and/or toxic effects, are DEHP with a preliminary reference value of 1600 mg/kg of household dust, dibutyl phthalate with 180 mg/kg of dust, short-chain chloroparaffins with 180 mg/kg of dust, permethrin with 110 mg/kg of dust, monobutyl tin

Local government household battery collection programs: Costs and benefits

Energy Technology Data Exchange (ETDEWEB)

Shapek, Raymond A [Department of Public Administration, University of Central Florida, Orlando, FL (United States)

1995-10-01

Nearly three billion dry-cell household batteries are discarded in the municipal waste stream annually. While the mercury content of newer batteries has been reduced, older batteries and the accumulated total of mercury and cadmium, as well as other metals in the newer batteries still constitute a potential health risk. Many communities have initiated collection programs to remove this source of contamination from the municipal waste stream, but most have not. Fourteen states have enacted legislation regulating the disposal of household batteries, while nine states require the collection of rechargeable batteries. This article describes the potential health risks associated with continued disposal and incineration of household dry-cell batteries, reviews a sampling of existing municipal collection programs in US communities, and examines the costs and benefits and program options of collection programs

Trace metal analysis of road dust by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Powell, M.J.; Liu, L.; Gnanalingham, N.; Peters, L.

2000-01-01

Dust from roads in an air impingement zone close to anthropogenic sources of air pollutants can be a concern for people living in the immediate vicinity. The Ministry of the Environment (MOE) has conducted a case study to monitor the concentration of uranium, strontium, thorium and arsenic in road dust from one such area. A method for the analysis of road dust by inductively coupled plasma mass spectrometry (ICP-MS) has been developed with detection limits in the ng/1 range. A digestion technique has been developed by conducting experiments using single and combinations of acids in open-vessel wet digestions. Accuracy has been determined by the use of matrix representative certified reference materials (CRMs). Digestion precision was determined by elemental concentration measurements of the most representative CRM through replicates. Spike recovery data were from 95% to 110% for all elements, and inter-method comparison studies between hydride generation atomic absorption spectrometry (AAS) inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-MS for arsenic and strontium show good agreement. (author)

Synthesis and application of a ternary composite of clay, saw-dust and peanut husks in heavy metal adsorption.

Science.gov (United States)

Mungondori, Henry H; Mtetwa, Sandile; Tichagwa, Lilian; Katwire, David M; Nyamukamba, Pardon

2017-05-01

The adsorption of a multi-component system of ferrous, chromium, copper, nickel and lead on single, binary and ternary composites was studied. The aim of the study was to investigate whether a ternary composite of clay, peanut husks (PH) and saw-dust (SD) exhibited a higher adsorption capacity than that of a binary system of clay and SD as well as a single component adsorbent of PH alone. The materials were used in their raw state without any chemical modifications. This was done to retain the cost effective aspect of the naturally occurring adsorbents. The adsorption capacities of the ternary composite for the heavy metals Fe 2+ , Cr 3+ , Cu 2+ , Ni 2+ and Pb 2+ were 41.7 mg/g, 40.0 mg/g, 25.5 mg/g, 41.5 mg/g and 39.0 mg/g, respectively. It was found that the ternary composite exhibited excellent and enhanced adsorption capacity compared with both a binary and single adsorbent for the heavy metals Fe 2+ , Ni 2+ and Cr 3+ . Characterization of the ternary composites was done using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Kinetic models and adsorption isotherms were also studied. The pseudo second order kinetic model and the Langmuir adsorption isotherm best described the adsorption mechanisms for the ternary composite towards each of the heavy metal ions.

COSMIC EVOLUTION OF DUST IN GALAXIES: METHODS AND PRELIMINARY RESULTS

International Nuclear Information System (INIS)

Bekki, Kenji

2015-01-01

We investigate the redshift (z) evolution of dust mass and abundance, their dependences on initial conditions of galaxy formation, and physical correlations between dust, gas, and stellar contents at different z based on our original chemodynamical simulations of galaxy formation with dust growth and destruction. In this preliminary investigation, we first determine the reasonable ranges of the most important two parameters for dust evolution, i.e., the timescales of dust growth and destruction, by comparing the observed and simulated dust mass and abundances and molecular hydrogen (H 2 ) content of the Galaxy. We then investigate the z-evolution of dust-to-gas ratios (D), H 2 gas fraction (f H 2 ), and gas-phase chemical abundances (e.g., A O = 12 + log (O/H)) in the simulated disk and dwarf galaxies. The principal results are as follows. Both D and f H 2 can rapidly increase during the early dissipative formation of galactic disks (z ∼ 2-3), and the z-evolution of these depends on initial mass densities, spin parameters, and masses of galaxies. The observed A O -D relation can be qualitatively reproduced, but the simulated dispersion of D at a given A O is smaller. The simulated galaxies with larger total dust masses show larger H 2 and stellar masses and higher f H 2 . Disk galaxies show negative radial gradients of D and the gradients are steeper for more massive galaxies. The observed evolution of dust masses and dust-to-stellar-mass ratios between z = 0 and 0.4 cannot be reproduced so well by the simulated disks. Very extended dusty gaseous halos can be formed during hierarchical buildup of disk galaxies. Dust-to-metal ratios (i.e., dust-depletion levels) are different within a single galaxy and between different galaxies at different z

COSMIC EVOLUTION OF DUST IN GALAXIES: METHODS AND PRELIMINARY RESULTS

Energy Technology Data Exchange (ETDEWEB)

Bekki, Kenji [ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia)

2015-02-01

We investigate the redshift (z) evolution of dust mass and abundance, their dependences on initial conditions of galaxy formation, and physical correlations between dust, gas, and stellar contents at different z based on our original chemodynamical simulations of galaxy formation with dust growth and destruction. In this preliminary investigation, we first determine the reasonable ranges of the most important two parameters for dust evolution, i.e., the timescales of dust growth and destruction, by comparing the observed and simulated dust mass and abundances and molecular hydrogen (H{sub 2}) content of the Galaxy. We then investigate the z-evolution of dust-to-gas ratios (D), H{sub 2} gas fraction (f{sub H{sub 2}}), and gas-phase chemical abundances (e.g., A {sub O} = 12 + log (O/H)) in the simulated disk and dwarf galaxies. The principal results are as follows. Both D and f{sub H{sub 2}} can rapidly increase during the early dissipative formation of galactic disks (z ∼ 2-3), and the z-evolution of these depends on initial mass densities, spin parameters, and masses of galaxies. The observed A {sub O}-D relation can be qualitatively reproduced, but the simulated dispersion of D at a given A {sub O} is smaller. The simulated galaxies with larger total dust masses show larger H{sub 2} and stellar masses and higher f{sub H{sub 2}}. Disk galaxies show negative radial gradients of D and the gradients are steeper for more massive galaxies. The observed evolution of dust masses and dust-to-stellar-mass ratios between z = 0 and 0.4 cannot be reproduced so well by the simulated disks. Very extended dusty gaseous halos can be formed during hierarchical buildup of disk galaxies. Dust-to-metal ratios (i.e., dust-depletion levels) are different within a single galaxy and between different galaxies at different z.

Dust grains from the heart of supernovae

Science.gov (United States)

Bocchio, M.; Marassi, S.; Schneider, R.; Bianchi, S.; Limongi, M.; Chieffi, A.

2016-03-01

Dust grains are classically thought to form in the winds of asymptotic giant branch (AGB) stars. However, there is increasing evidence today for dust formation in supernovae (SNe). To establish the relative importance of these two classes of stellar sources of dust, it is important to know the fraction of freshly formed dust in SN ejecta that is able to survive the passage of the reverse shock and be injected in the interstellar medium. With this aim, we have developed a new code, GRASH_Rev, that allows following the dynamics of dust grains in the shocked SN ejecta and computing the time evolution of the mass, composition, and size distribution of the grains. We considered four well-studied SNe in the Milky Way and Large Magellanic Cloud: SN 1987A, CasA, the Crab nebula, and N49. These sources have been observed with both Spitzer and Herschel, and the multiwavelength data allow a better assessment the mass of warm and cold dust associated with the ejecta. For each SN, we first identified the best explosion model, using the mass and metallicity of the progenitor star, the mass of 56Ni, the explosion energy, and the circumstellar medium density inferred from the data. We then ran a recently developed dust formation model to compute the properties of freshly formed dust. Starting from these input models, GRASH_Rev self-consistently follows the dynamics of the grains, considering the effects of the forward and reverse shock, and allows predicting the time evolution of the dust mass, composition, and size distribution in the shocked and unshocked regions of the ejecta. All the simulated models aagree well with observations. Our study suggests that SN 1987A is too young for the reverse shock to have affected the dust mass. Hence the observed dust mass of 0.7-0.9 M⊙ in this source can be safely considered as indicative of the mass of freshly formed dust in SN ejecta. Conversely, in the other three SNe, the reverse shock has already destroyed between 10-40% of the

DUST DESTRUCTION RATES AND LIFETIMES IN THE MAGELLANIC CLOUDS

Energy Technology Data Exchange (ETDEWEB)

Temim, Tea; Dwek, Eli; Boyer, Martha L. [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Tchernyshyov, Kirill; Meixner, Margaret [Department of Physics and Astronomy, The Johns Hopkins University, 366 Bloomberg Center, 3400 North Charles Street, Baltimore, MD 21218 (United States); Gall, Christa [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Roman-Duval, Julia, E-mail: tea.temim@nasa.gov [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2015-02-01

The dust budget in galaxies depends on the rate at which dust grains are created in different stellar sources and destroyed by interstellar shocks. Because of their extensive wavelength coverage, proximity, and nearly face-on geometry, the Magellanic Clouds (MCs) provide a unique opportunity to study these processes in great detail. In this paper, we use the complete sample of supernova remnants (SNRs) in the MCs to calculate the lifetimes and destruction efficiencies of silicate and carbon dust. We find dust lifetimes of 22 ± 13 Myr (30 ± 17 Myr) for silicate (carbon) grains in the LMC, and 54 ± 32 Myr (72 ± 43 Myr) for silicate (carbon) grains in the SMC. The corresponding dust destruction rates are 2.3 × 10{sup –2} M {sub ☉} yr{sup –1} (5.9 × 10{sup –3} M {sub ☉} yr{sup –1}) and 3.0 × 10{sup –3} M {sub ☉} yr{sup –1} (5.6 × 10{sup –4} M {sub ☉} yr{sup –1}) for silicate (carbon) grains in the LMC and SMC, respectively. The significantly shorter lifetimes in the MCs, as compared to the Milky Way, are explained as the combined effect of their lower total dust mass and preferentially higher dust-to-gas (D2G) mass ratios in the vicinity of the SNRs. We find that the maximum dust injection rates by asymptotic giant branch stars and core collapse supernovae are an order of magnitude lower than the dust destruction rates by the SNRs, suggesting that most of the dust may be reconstituted in dense molecular clouds. We also discuss the dependence of the dust destruction rate on the local D2G mass ratio, ambient gas density, and metallicity, as well as the application of our results to other galaxies and dust evolution models.

Accumulation and distribution characteristics of platinum group elements in roadside dusts in Beijing, China.

Science.gov (United States)

Gao, Bo; Yu, Yanke; Zhou, Huaidong; Lu, Jin

2012-06-01

The concentrations, distribution, and accumulation of platinum group elements (PGEs) were investigated in roadside dusts collected in four different foundational areas in Beijing during February to May 2010. The results showed that PGE levels in all samples were above the average upper crust values, with mean concentrations of 57.5 ng · g(-1) Pd, 28.2 ng · g(-1) Pt, and 9.8 ng · g(-1) Rh, respectively. Palladium concentration has increased rapidly in recent years. The rank of PGE levels in four different functional regions for roadside dusts was: heavy density traffic area > residential area > educational area > tourism area. Palladium, Pt, and Rh concentrations in dusts showed strong positive correlations, indicating a common traffic-related source of these metals. Meanwhile, PGEs in these samples were not correlated with other traffic-related metals except for Cr. The average PGE ratios of road dusts from Beijing were consistent with those in Germany and Western Australia, but lower than those in the United States and Mexico, indicating that various catalyst productions were used in different countries. In addition, grain-size partitioning of PGEs in dusts indicated that concentrations of PGEs differed from one particle size to another. The coarse fraction had higher PGE concentrations than the fine fraction in roadside dusts. These results showed that autocatalyst PGE contamination estimates in the environment would be significantly underestimated if only a fine-grain size fraction (<0.063 mm) is analyzed. Copyright © 2012 SETAC.

DustEM: Dust extinction and emission modelling

Science.gov (United States)

Compiègne, M.; Verstraete, L.; Jones, A.; Bernard, J.-P.; Boulanger, F.; Flagey, N.; Le Bourlot, J.; Paradis, D.; Ysard, N.

2013-07-01

DustEM computes the extinction and the emission of interstellar dust grains heated by photons. It is written in Fortran 95 and is jointly developed by IAS and CESR. The dust emission is calculated in the optically thin limit (no radiative transfer) and the default spectral range is 40 to 108 nm. The code is designed so dust properties can easily be changed and mixed and to allow for the inclusion of new grain physics.

Valorization of GaN based metal-organic chemical vapor deposition dust a semiconductor power device industry waste through mechanochemical oxidation and leaching: A sustainable green process

Energy Technology Data Exchange (ETDEWEB)

Swain, Basudev, E-mail: Swain@iae.re.kr [Institute for Advanced Engineering (IAE), Advanced Materials & Processing Center, Yongin-Si 449-863 (Korea, Republic of); Mishra, Chinmayee; Lee, Chan Gi; Park, Kyung-Soo [Institute for Advanced Engineering (IAE), Advanced Materials & Processing Center, Yongin-Si 449-863 (Korea, Republic of); Lee, Kun-Jae [Department of Energy Engineering, Dankook University, Cheonan 330-714 (Korea, Republic of)

2015-07-15

Dust generated during metal organic vapor deposition (MOCVD) process of GaN based semiconductor power device industry contains significant amounts of gallium and indium. These semiconductor power device industry wastes contain gallium as GaN and Ga{sub 0.97}N{sub 0.9}O{sub 0.09} is a concern for the environment which can add value through recycling. In the present study, this waste is recycled through mechanochemical oxidation and leaching. For quantitative recovery of gallium, two different mechanochemical oxidation leaching process flow sheets are proposed. In one process, first the Ga{sub 0.97}N{sub 0.9}O{sub 0.09} of the MOCVD dust is leached at the optimum condition. Subsequently, the leach residue is mechanochemically treated, followed by oxidative annealing and finally re-leached. In the second process, the MOCVD waste dust is mechanochemically treated, followed by oxidative annealing and finally leached. Both of these treatment processes are competitive with each other, appropriate for gallium leaching and treatment of the waste MOCVD dust. Without mechanochemical oxidation, 40.11 and 1.86 w/w% of gallium and Indium are leached using 4 M HCl, 100 °C and pulp density of 100 kg/m{sup 3,} respectively. After mechanochemical oxidation, both these processes achieved 90 w/w% of gallium and 1.86 w/w% of indium leaching at their optimum condition. - Highlights: • Waste MOCVD dust is treated through mechanochemical leaching. • GaN is hardly leached, and converted to NaGaO{sub 2} through ball milling and annealing. • Process for gallium recovery from waste MOCVD dust has been developed. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} is revealed. • Solid-state chemistry involved in this process is reported.

Lack of dust in quasar absorption line systems

International Nuclear Information System (INIS)

Jura, M.

1977-01-01

It is stated that the origin of absorption line systems in quasars is still uncertain. Most such systems apparently have atomic hydrogen column densities of the order of 10 19 /cm 2 , but at least two quasars, 1331 + 170 and PHL957, have such strong Lyman α absorption lines that atomic hydrogen column densities of the order of 10 21 /cm 2 are indicated. It should be possible to observe the dust produced 2,200 A extinction feature as it is red shifted into the visible, and to determine whether absorption line systems are produced in spiral galaxies where the dust content is similar to that in the interstellar medium. It has been argued that the emission line regions of quasars generally lack dust and that towards PHL957 the 2,200 A feature is absent. The present author argues that dust similar to that found in the interstellar medium is not found towards the quasars 1331 + 170 and PHL957. This could explain why H 2 is not found towards PHL957, and it indicates that the absorption line systems in quasars are not produced in spiral galaxies similar to our own. It seems from the analysis presented that the dust-to-gas ratio towards 1331 + 170 is at least a factor of 20 less than in the interstellar medium, and there is no reason to suppose that this lack of dust results from a lack of metals It is concluded that there seems to be a lack of normal dust towards PHL957 by at least a factor of two; and that the absorption region towards 1331 + 170 and probably the region towards PHL957 are lacking dust similar to that in our own galaxy. This can explain the lack of H 2 in these systems. (U.K.)

Valorization of GaN based metal-organic chemical vapor deposition dust a semiconductor power device industry waste through mechanochemical oxidation and leaching: A sustainable green process.

Science.gov (United States)

Swain, Basudev; Mishra, Chinmayee; Lee, Chan Gi; Park, Kyung-Soo; Lee, Kun-Jae

2015-07-01

Dust generated during metal organic vapor deposition (MOCVD) process of GaN based semiconductor power device industry contains significant amounts of gallium and indium. These semiconductor power device industry wastes contain gallium as GaN and Ga0.97N0.9O0.09 is a concern for the environment which can add value through recycling. In the present study, this waste is recycled through mechanochemical oxidation and leaching. For quantitative recovery of gallium, two different mechanochemical oxidation leaching process flow sheets are proposed. In one process, first the Ga0.97N0.9O0.09 of the MOCVD dust is leached at the optimum condition. Subsequently, the leach residue is mechanochemically treated, followed by oxidative annealing and finally re-leached. In the second process, the MOCVD waste dust is mechanochemically treated, followed by oxidative annealing and finally leached. Both of these treatment processes are competitive with each other, appropriate for gallium leaching and treatment of the waste MOCVD dust. Without mechanochemical oxidation, 40.11 and 1.86 w/w% of gallium and Indium are leached using 4M HCl, 100°C and pulp density of 100 kg/m(3,) respectively. After mechanochemical oxidation, both these processes achieved 90 w/w% of gallium and 1.86 w/w% of indium leaching at their optimum condition. Copyright © 2015 Elsevier Inc. All rights reserved.

DUST PRODUCTION AND PARTICLE ACCELERATION IN SUPERNOVA 1987A REVEALED WITH ALMA

Energy Technology Data Exchange (ETDEWEB)

Indebetouw, R.; Chevalier, R. [Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904 (United States); Matsuura, M.; Barlow, M. J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Dwek, E. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Zanardo, G. [International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, Crawley, WA 6009 (Australia); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Bouchet, P. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Burrows, D. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Clayton, G. C. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Fransson, C.; Lundqvist, P. [Department of Astronomy and the Oskar Klein Centre, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Gaensler, B. [Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO) (Australia); Kirshner, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Lakićević, M. [Lennard-Jones Laboratories, Keele University, ST5 5BG (United Kingdom); Long, K. S.; Meixner, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Martí-Vidal, I. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Marcaide, J. [Universidad de Valencia, C/Dr. Moliner 50, E-46100 Burjassot (Spain); McCray, R., E-mail: remy@virginia.edu [Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, UCB 391, Boulder, CO 80309 (United States); and others

2014-02-10

Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M {sub ☉}). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

Exposures Related to House Dust Microbiota in a U.S. Farming Population.

Science.gov (United States)

Lee, Mi Kyeong; Carnes, Megan U; Butz, Natasha; Azcarate-Peril, M Andrea; Richards, Marie; Umbach, David M; Thorne, Peter S; Beane Freeman, Laura E; Peddada, Shyamal D; London, Stephanie J

2018-06-01

Environmental factors can influence the house dust microbiota, which may impact health outcomes. Little is known about how farming exposures impact the indoor microbiota. We aimed to identify exposures related to bacterial communities in house dust in a U.S. farming population. We used 16S rRNA amplicon sequencing to characterize bacterial communities in vacuumed dust samples from the bedrooms of a subset of 879 households of farmers and farmers' spouses enrolled in the Agricultural Lung Health Study (ALHS), a case-control study of asthma nested within the Agricultural Health Study (AHS) in North Carolina and Iowa. Information on current farming (past 12 mo), including both crop and animal farming, and other potential microbial sources was obtained via questionnaires. We used linear regression to evaluate associations between exposures and bacterial diversity within each sample, analysis of similarity (ANOSIM), and permutational multivariate analysis of variance (PERMANOVA) to identify exposures related to diversity between samples, and analysis of composition of microbiome to examine whether exposures related to diversity were also related to differential abundance of specific operational taxonomic units (OTUs). Current farming was positively associated with bacterial diversity in house dust, with or without adjustment for nonfarm exposures related to diversity, including presence of indoor pets, home condition, and season of dust collection. Many taxa exhibited differential abundance related to farming. Some taxa in the phyla Chloroflexi and Verrucomicrobia were associated [false discovery rate (FDR)<0.05] with farming but not with other nonfarm factors. Many taxa correlated with the concentration of house dust of endotoxin, commonly studied as a general marker of exposure to the farming environment. In this farming population, house dust microbiota differed by current farming status. Understanding the determinants of the indoor microbiota is the first step

Occupational dust exposure and head and neck squamous cell carcinoma risk in a population-based case–control study conducted in the greater Boston area

International Nuclear Information System (INIS)

Langevin, Scott M; McClean, Michael D; Michaud, Dominique S; Eliot, Melissa; Nelson, Heather H; Kelsey, Karl T

2013-01-01

Head and neck cancers account for an estimated 549,000 global cancer diagnoses each year. While tobacco use, alcohol consumption, and HPV16 infection are considered to be the major risk factors for this disease, occupational risk factors, including exposure to asbestos, have also been described, although dust exposures other than asbestos have been historically understudied. We have investigated the relationship between occupational exposures to five types of dusts, including sawdust, concrete dust, leather dust, metal dust, and chimney soot, and head and neck squamous cell carcinomas (HNSCC) in the greater Boston area. We report findings from a population-based case–control study involving 951 incident HNSCC cases and 1193 controls, frequency matched on age (±3 years), sex, and town/neighborhood of residence. Multivariable logistic regression was used to assess the association between occupational exposure to each type of dust and HNSCC, overall and by primary tumor site. After adjusting for age, sex, race, smoking, alcohol consumption, education, and HPV16 serology, laryngeal carcinoma risk increased for each decade of occupational exposure to sawdust (OR = 1.2, 95% CI: 1.0, 1.3) and metal dust (OR = 1.2, 95% CI: 1.0, 1.4); and HNSCC risk increased for each decade of occupational leather dust exposure (OR = 1.5, 95% CI: 1.2, 1.9). We have provided evidence for an association between occupational sawdust and metal dust and laryngeal squamous cell carcinoma, and leather dust and HNSCC, with increasing risk with longer duration at the exposed occupation

Occupational dust exposure and head and neck squamous cell carcinoma risk in a population-based case-control study conducted in the greater Boston area.

Science.gov (United States)

Langevin, Scott M; McClean, Michael D; Michaud, Dominique S; Eliot, Melissa; Nelson, Heather H; Kelsey, Karl T

2013-12-01

Head and neck cancers account for an estimated 549,000 global cancer diagnoses each year. While tobacco use, alcohol consumption, and HPV16 infection are considered to be the major risk factors for this disease, occupational risk factors, including exposure to asbestos, have also been described, although dust exposures other than asbestos have been historically understudied. We have investigated the relationship between occupational exposures to five types of dusts, including sawdust, concrete dust, leather dust, metal dust, and chimney soot, and head and neck squamous cell carcinomas (HNSCC) in the greater Boston area. We report findings from a population-based case-control study involving 951 incident HNSCC cases and 1193 controls, frequency matched on age (±3 years), sex, and town/neighborhood of residence. Multivariable logistic regression was used to assess the association between occupational exposure to each type of dust and HNSCC, overall and by primary tumor site. After adjusting for age, sex, race, smoking, alcohol consumption, education, and HPV16 serology, laryngeal carcinoma risk increased for each decade of occupational exposure to sawdust (OR = 1.2, 95% CI: 1.0, 1.3) and metal dust (OR = 1.2, 95% CI: 1.0, 1.4); and HNSCC risk increased for each decade of occupational leather dust exposure (OR = 1.5, 95% CI: 1.2, 1.9). We have provided evidence for an association between occupational sawdust and metal dust and laryngeal squamous cell carcinoma, and leather dust and HNSCC, with increasing risk with longer duration at the exposed occupation. © 2013 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Stop dust : a communication support for mining permit application at Bilina opencast mine

International Nuclear Information System (INIS)

Budinsky, V.; Paroha, L.

2010-01-01

This paper reported on a problem solving process called stop dust that has been launched by a brown coal mining company to improve ambient air quality and to reduce health risks for the population living in the area close to the Bilina opencast mine in the Czech Republic. The initiative also involved the efforts of local stakeholders and an independent expert team. The concept for stop dust reflected the fact that particles emitted by households through burning fossil fuels, wood, and litter in old stoves and by road transportation were much smaller and with higher health impacts, than than those emitted by coal mining activity. The paper described the Severoceske doly Company and Bilina Mine. The primary goal of stop dust was also outlined. The goal was to decrease particulate matter levels and related health risks in the communities surrounding Bilina opencast mine through feasible cost-effective measures aimed at background pollution sources. Specific topics that were addressed in the paper included particulate matter and limit values for the protection of human health; comparison of particulate matter to a hair; particulate matter dispersion modelling as part of the Bilina Mine environmental impact assessment process; and the various phases of stop dust. 3 refs., 2 tabs., 5 figs.

Current situation of used household batteries in Iran and appropriate management policies.

Science.gov (United States)

Zand, A Daryabeigi; Abduli, M A

2008-11-01

Used household batteries are considered as hazardous wastes in many countries due to the potential environmental and human health risks associated with the heavy metals present in batteries. This article presents the current situation of waste household batteries and policies in Iran. Iran with more than 70 million people is a developing country where latest technologies like cell phones and laptops are in widespread use and battery consumption increases accordingly. The household battery demand in Iran has rapidly grown since 2001 and it is expected to increase more quickly in next years, due to increasing technological development. Based on the available data, more than 9800 metric tons of household batteries were imported into Iran in recent decade, with the market value of about US$ 42.6 million. At present, there is no program available in Iran regarding to collection, separation, recycling or safe disposal of used batteries. Therefore, almost all of the spent household are discarded into municipal solid waste (MSW) and sent to sanitary landfills. Appropriate policies to meet safe disposal of household batteries in Iran is also discussed in this investigation.

Dust acoustic shock wave at high dust density

International Nuclear Information System (INIS)

Ghosh, Samiran; Sarkar, Susmita; Khan, Manoranjan; Avinash, K.; Gupta, M. R.

2003-01-01

Dust acoustic (DA) shock wave at high dust density, i.e., the dust electroacoustic (DEA) or dust Coulomb (DC) shock wave has been investigated incorporating the nonadiabatic dust charge variation. The nonlinear DEA (DC) shock wave is seen to be governed by the Korteweg-de Vries Burger equation, in which the Burger term is proportional to the nonadiabaticity generated dissipation. It is seen that the shock strength decreases but after reaching minimum, it increases as the dust space charge density |q d n d | increases and the shock strength of DA wave is greater than that of DEA (DC) wave. Moreover the DEA (DC) shock width increases appreciably with increase mass m i of the ion component of the dusty plasma but for DA shock wave the effect is weak

Infrared Spectroscopic Studies of the Properties of Dust in the Ejecta of Galactic Oxygen-Rich Asymptotic Giant Branch Stars

Science.gov (United States)

Sargent, Benjamin A.; Srinivasan, Sundar; Kastner, Joel; Meixner, Margaret; Riley, Allyssa

2018-06-01

We are conducting a series of infrared studies of large samples of mass-losing asymptotic giant branch (AGB) stars to explore the relationship between the composition of evolved star ejecta and host galaxy metallicity. Our previous studies focused on mass loss from evolved stars in the relatively low-metallicity Large and Small Magellanic Clouds. In our present study, we analyze dust in the mass-losing envelopes of AGB stars in the Galaxy, with special focus on the ejecta of oxygen-rich (O-rich) AGB stars. We have constructed detailed dust opacity models of AGB stars in the Galaxy for which we have infrared spectra from, e.g., the Spitzer Space Telescope Infrared Spectrograph (IRS). This detailed modeling of dust features in IRS spectra informs our choice of dust properties to use in radiative transfer modeling of the broadband SEDs of Bulge AGB stars. We investigate the effects of dust grain composition, size, shape, etc. on the AGB stars' infrared spectra, studying both the silicate dust and the opacity source(s) commonly attributed to alumina (Al2O3). BAS acknowledges funding from NASA ADAP grant 80NSSC17K0057.

Geochemical characterization of critical dust source regions in the American West

Science.gov (United States)

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

2017-10-01

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

Impact of metals in surface matrices from formal and informal electronic-waste recycling around Metro Manila, the Philippines, and intra-Asian comparison

International Nuclear Information System (INIS)

Fujimori, Takashi; Takigami, Hidetaka; Agusa, Tetsuro; Eguchi, Akifumi; Bekki, Kanae; Yoshida, Aya; Terazono, Atsushi; Ballesteros, Florencio C.

2012-01-01

Highlights: ► We quantified 11 metals in surface matrices from e-waste recycling sites at the Philippines. ► Dust had statistical higher levels of metal contamination and health risk compared to soil. ► Formal and informal sites had different metal contaminations. ► Intra-Asian comparison provided common insight on metal contamination from e-waste recycling. - Abstract: We report concentrations, enrichment factors, and hazard indicators of 11 metals (Ag, As, Cd, Co, Cu, Fe, In, Mn, Ni, Pb, and Zn) in soil and dust surface matrices from formal and informal electronic waste (e-waste) recycling sites around Metro Manila, the Philippines, referring to soil guidelines and previous data from various e-waste recycling sites in Asia. Surface dust from e-waste recycling sites had higher levels of metal contamination than surface soil. Comparison of formal and informal e-waste recycling sites (hereafter, “formal” and “informal”) revealed differences in specific contaminants. Formal dust contained a mixture of serious pollutant metals (Ni, Cu, Pb, and Zn) and Cd (polluted modestly), quite high enrichment metals (Ag and In), and crust-derived metals (As, Co, Fe, and Mn). For informal soil, concentration levels of specific metals (Cd, Co, Cu, Mn, Ni, Pb, and Zn) were similar among Asian recycling sites. Formal dust had significantly higher hazardous risk than the other matrices (p < 0.005), excluding informal dust (p = 0.059, almost significant difference). Thus, workers exposed to formal dust should protect themselves from hazardous toxic metals (Pb and Cu). There is also a high health risk for children ingesting surface matrices from informal e-waste recycling sites.

The Chemistry of Population III Supernova Ejecta. II. The Nucleation of Molecular Clusters as a Diagnostic for Dust in the Early Universe

Science.gov (United States)

Cherchneff, Isabelle; Dwek, Eli

2010-04-01

We study the formation of molecular precursors to dust in the ejecta of Population III supernovae (Pop. III SNe) using a chemical kinetic approach to follow the evolution of small dust cluster abundances from day 100 to day 1000 after explosion. Our work focuses on zero-metallicity 20 M sun and 170 M sun progenitors, and we consider fully macroscopically mixed and unmixed ejecta. The dust precursors comprise molecular chains, rings, and small clusters of chemical composition relevant to the initial elemental composition of the ejecta under study. The nucleation stage for small silica, metal oxides and sulfides, pure metal, and carbon clusters is described with a new chemical reaction network highly relevant to the kinetic description of dust formation in hot circumstellar environments. We consider the effect of the pressure dependence of critical nucleation rates and test the impact of microscopically mixed He+ on carbon dust formation. Two cases of metal depletion on silica clusters (full and no depletion) are considered to derive upper limits to the amounts of dust produced in SN ejecta at 1000 days, while the chemical composition of clusters gives a prescription for the type of dust formed in Pop. III SNe. We show that the cluster mass produced in the fully mixed ejecta of a 170 M sun progenitor is ~ 25 M sun whereas its 20 M sun counterpart forms ~ 0.16 M sun of clusters. The unmixed ejecta of a 170 M sun progenitor SN synthesize ~5.6 M sun of small clusters, while its 20 M sun counterpart produces ~0.103 M sun. Our results point to smaller amounts of dust formed in the ejecta of Pop. III SNe by a factor of ~ 5 compared to values derived by previous studies, and to different dust chemical compositions. Such deviations result from some erroneous assumptions made, the inappropriate use of classical nucleation theory to model dust formation, and the omission of the synthesis of molecules in SN ejecta. We also find that the unmixed ejecta of massive Pop. III SNe

Composition and source apportionment of dust fall around a natural lake.

Science.gov (United States)

Latif, Mohd Talib; Ngah, Sofia Aida; Dominick, Doreena; Razak, Intan Suraya; Guo, Xinxin; Srithawirat, Thunwadee; Mushrifah, Idris

2015-07-01

The aim of this study was to determine the source apportionment of dust fall around Lake Chini, Malaysia. Samples were collected monthly between December 2012 and March 2013 at seven sampling stations located around Lake Chini. The samples were filtered to separate the dissolved and undissolved solids. The ionic compositions (NO3-, SO4(2-), Cl- and NH4+) were determined using ion chromatography (IC) while major elements (K, Na, Ca and Mg) and trace metals (Zn, Fe, Al, Ni, Mn, Cr, Pb and Cd) were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the average concentration of total solids around Lake Chini was 93.49±16.16 mg/(m2·day). SO4(2-), Na and Zn dominated the dissolved portion of the dust fall. The enrichment factors (EF) revealed that the source of the trace metals and major elements in the rain water was anthropogenic, except for Fe. Hierarchical agglomerative cluster analysis (HACA) classified the seven monitoring stations and 16 variables into five groups and three groups respectively. A coupled receptor model, principal component analysis multiple linear regression (PCA-MLR), revealed that the sources of dust fall in Lake Chini were dominated by agricultural and biomass burning (42%), followed by the earth's crust (28%), sea spray (16%) and a mixture of soil dust and vehicle emissions (14%). Copyright © 2015. Published by Elsevier B.V.

An analysis of the correlation between dust storms in Korea and 137Cs nuclide concentration

International Nuclear Information System (INIS)

Choi, Soo-won; Kim, Jeong-hun; Shin, Sang-hwa; Hwang, Joo-ho

2008-01-01

Dust storms occur in Korea during spring time when fine dust is blown in from the far western regions of western China and Mongolia. A fine powdery dust is blown up into the sky and enters the upper reaches of the atmosphere where it is carried easterly across China then slowly falls to the ground on the Korean peninsula and Japan. The dust originates mostly in the Gobi dessert of China, as well as the yellow earth regions in the middle and upper streams of the Yellow river in China. Previous studies on dust storms have been limited to following or estimating their courses, distribution and frequency, or distribution of the heavy metals they transmit. However, since radionuclides exist in the dust, they must also exist in the dust storms. In this study, we analyzed the correlation of :1 37 Cs nuclide concentration based on a count of annual dust storm occurrence in the city of Suwon, South Korea and assessed seasonal differences of 137 Cs nuclide concentration

Cometary Dust

Science.gov (United States)

Levasseur-Regourd, Anny-Chantal; Agarwal, Jessica; Cottin, Hervé; Engrand, Cécile; Flynn, George; Fulle, Marco; Gombosi, Tamas; Langevin, Yves; Lasue, Jérémie; Mannel, Thurid; Merouane, Sihane; Poch, Olivier; Thomas, Nicolas; Westphal, Andrew

2018-04-01

This review presents our understanding of cometary dust at the end of 2017. For decades, insight about the dust ejected by nuclei of comets had stemmed from remote observations from Earth or Earth's orbit, and from flybys, including the samples of dust returned to Earth for laboratory studies by the Stardust return capsule. The long-duration Rosetta mission has recently provided a huge and unique amount of data, obtained using numerous instruments, including innovative dust instruments, over a wide range of distances from the Sun and from the nucleus. The diverse approaches available to study dust in comets, together with the related theoretical and experimental studies, provide evidence of the composition and physical properties of dust particles, e.g., the presence of a large fraction of carbon in macromolecules, and of aggregates on a wide range of scales. The results have opened vivid discussions on the variety of dust-release processes and on the diversity of dust properties in comets, as well as on the formation of cometary dust, and on its presence in the near-Earth interplanetary medium. These discussions stress the significance of future explorations as a way to decipher the formation and evolution of our Solar System.

Evaluation of some Heavy Metals Loading in Dust Fall of Three ...

African Journals Online (AJOL)

PROF HORSFALL

are detrimental to health status of users of the park. The monthly mean .... The high Cu content could also cause bad odour to water bodies in this vicinity. However, in terms of .... Chemical composition of traffic generated dust and its impact on ...

Thermomagnetic identification of manganese and iron minerals present in soils and industrial dusts

Science.gov (United States)

Wawer, Małgorzata; Rachwał, Marzena; Jabłońska, Mariola; Krzykawski, Tomasz; Magiera, Tadeusz

2017-04-01

Many industries (e.g. metallurgy, power, cement, and coking plants) constitute a sources of industrial dusts containing technogenic magnetic particles (TMP). TMP are mostly iron oxides with ferrimagnetic or antiferromagnetic properties, therefore their presence in dusts, soils and sediments can be easily detected by magnetic susceptibility measurements. TMP, thanks their specific mineral and magnetic properties, and well developed specific surface area, are characterized by a chemical affinity for some elements like heavy metals. The main objective of this study was identification of manganese and iron (hydro)oxides occurring in industrial dusts and soils being under their deposition for long time period. In principle, Mn and Fe (hydro)oxides present in these samples originate from high-temperature technological processes. Soils samples (collected from different soil horizons) taken from surroundings of power station, iron/steel and non-ferrous plants as well as metallurgical dusts and fly ashes from power stations were subjected to investigation. During the studies temperature dependent magnetic susceptibility measurements and X-ray powder diffraction analyses were applied. Thermomagnetic analyses (K-T) revealed differences between samples from particular industries, however an inflexion at 450-500°C of all curves was observed indicating a probable occurrence of maghemite- or titanomagnetite-like phases. The curves of TMP emitted by power plants have inflection at 580 °C indicating that magnetite was the main magnetic phase. In case of TMP originated from non-ferrous metal smelting additional curve deflection at 130 and 210 °C occurred relating to intermediate titanomagnetite or iron sulfides. X-ray diffraction proved the occurrence of magnetite and maghemite in almost all samples, especially connected with power industry and iron/steel metallurgy. Mineral analysis revealed that kind of industrial process influenced on the dominating mineral forms found in

THE DUST PROPERTIES OF z ∼ 3 MIPS-LBGs FROM PHOTOCHEMICAL MODELS

International Nuclear Information System (INIS)

Fan, X. L.; Pipino, A.; Matteucci, F.

2013-01-01

The stacked spectral energy distribution (SED) 24 μm Lyman break galaxies (MIPS-LBGs) detected by the Multiband Imaging Photometer for Spitzer (MIPS) is fitted by means of the spectrophotometric model GRASIL with an ''educated'' fitting approach which benefits from the results of chemical evolution models. The star formation rate-age-metallicity degeneracies of SED modeling are broken by using star formation history (SFH) and chemical enrichment history suggested by chemical models. The dust mass, dust abundance, and chemical pattern of elements locked in the dust component are also directly provided by chemical models. Using our new ''fitting'' approach, we derive the total mass M tot , stellar mass M * , gas mass M g , dust mass M d , age, and star formation rate (SFR) of the stacked MIPS-LBG in a self-consistent way. Our estimate of M * = 8 × 10 10 of the stacked MIPS-LBG agrees with other works based on UV-optical SED fitting. We suggest that the MIPS-LBGs at z ∼ 3 are young (0.3-0.6 Gyr), massive (M tot ∼ 10 11 M ☉ ), dusty (M d ∼ 10 8 M ☉ ), and metal-rich (Z ∼ Z ☉ ) progenitors of elliptical galaxies undergoing a strong burst of star formation (SFR ∼ 200 M ☉ yr –1 ). Our estimate of M d = 7 × 10 7 M ☉ of the stacked MIPS-LBG is about a factor of eight lower than the estimated value based on single temperature graybody fitting, suggesting that self-consistent SED models are needed to estimate dust mass. By comparing with Milky Way molecular cloud and dust properties, we suggest that denser and dustier environments and flatter dust size distribution are likely in high-redshift massive star-forming galaxies. These dust properties, as well as the different types of SFHs, can cause different SED shapes between high-redshift star-forming ellipticals and local starburst templates. This discrepancy of SED shapes could in turn explain the non-detection at submillimeter wavelengths of IR luminous (L IR ⪰10 12 L ☉ ) MIPS-LBGs.

How large is the cosmic dust flux into the Earth's atmosphere?

Science.gov (United States)

Plane, John; Janches, Diego; Gomez-Martin, Juan Carlos; Bones, David; Diego Carrillo-Sanchez, Juan; James, Sandy; Nesvorny, David; Pokorny, Petr

2016-07-01

Cosmic dust particles are produced in the solar system from the sublimation of comets as they orbit close to the sun, and also from collisions between asteroids in the belt between Mars and Jupiter. Current estimates of the magnitude of the cosmic dust input rate into the Earth's atmosphere range from 2 to well over 100 tons per day, depending on whether the measurements are made in space, in the middle atmosphere, or at the surface in polar ice cores. This nearly 2 order-of-magnitude discrepancy indicates that there are serious flaws in the interpretation of observations that have been used to make the estimates. Dust particles enter the atmosphere at hyperthermal velocities (11 - 72 km s ^{-1}), and mostly ablate at heights between 80 and 120 km in a region of the atmosphere known as the mesosphere/lower thermosphere (MLT). The resulting metal vapours (Fe, Mg, Si and Na etc.) then oxidize and recondense to form nm-size particles, termed "meteoric smoke". These particles are too small to sediment downwards. Instead, they are transported by the general circulation of the atmosphere, taking roughly 5 years to reach the surface. There is great interest in the role smoke particles play as condensation nuclei of noctilucent ice clouds in the mesosphere, and polar stratospheric clouds in the lower stratosphere. Various new estimates of the dust input will be discussed. The first is from a zodiacal dust cloud model which predicts that more than 90% of the dust entering the atmosphere comes from Jupiter Family Comets; this model is constrained by observations of the zodiacal cloud using the IRAS, COBE and Planck satellites. The cometary dust is predicted to mostly be in a near-prograde orbit, entering the atmosphere with an average velocity around 14 km s ^{-1}. The total dust input should then be about 40 t d ^{-1}. However, relatively few of these particles are observed, even by the powerful Arecibo 430 MHz radar. Coupled models of meteoroid differential ablation

Assessing the bioavailability and risk from metal-contaminated ...

Science.gov (United States)

Exposure to contaminated soil and dust is an important pathway in human health risk assessment. Physical and chemical characteristics, as well as biological factors, determine the bioaccessibility/bioavailability of soil and dust contaminants. Within a single sample, contamination may arise from multiple sources of toxic elements that may exist as different forms (species) which impact bioavailability. In turn, the bioaccessibility/bioavailability of soil and dust contaminants has a direct impact on human health risk assessment and risk management practices. Novel research efforts focusing on development and application of in vitro and in vivo methods to measure the bioaccessibility/bioavailability of metal contaminated soils have advanced in the past few years. The objective of this workshop was to focus on recent developments in assessing the bioaccessibility/bioavailability of arsenic contaminated soils, metal contamination in urban residences in Canada and potential children’s exposures to toxic elements in house dust, a community-based study known as the West Oakland Residential Lead Assessment , studies of the bioavailability of soil cadmium, chromium, nickel and mercury and human exposures to contaminated Brownfield soils. These presentations covered issues related to human health and bioavailability along with the most recent studies on community participation in assessing metal contamination, studies of exposures to residential contamination, and

Household Finance

OpenAIRE

Campbell, John

2006-01-01

The welfare benefits of financial markets depend in large part on how effectively households use these markets. The study of household finance is challenging because household behavior is difficult to measure accurately, and because households face constraints that are not captured by textbook models, including fixed costs, uninsurable income risk, borrowing constraints, and contracts that are non-neutral with respect to inflation. Evidence on participation, diversification, and the exercise ...

Household Air Pollution: Sources and Exposure Levels to Fine Particulate Matter in Nairobi Slums

Directory of Open Access Journals (Sweden)

Kanyiva Muindi

2016-07-01

Full Text Available With 2.8 billion biomass users globally, household air pollution remains a public health threat in many low- and middle-income countries. However, little evidence on pollution levels and health effects exists in low-income settings, especially slums. This study assesses the levels and sources of household air pollution in the urban slums of Nairobi. This cross-sectional study was embedded in a prospective cohort of pregnant women living in two slum areas—Korogocho and Viwandani—in Nairobi. Data on fuel and stove types and ventilation use come from 1058 households, while air quality data based on the particulate matters (PM2.5 level were collected in a sub-sample of 72 households using the DustTrak™ II Model 8532 monitor. We measured PM2.5 levels mainly during daytime and using sources of indoor air pollutions. The majority of the households used kerosene (69.7% as a cooking fuel. In households where air quality was monitored, the mean PM2.5 levels were high and varied widely, especially during the evenings (124.6 µg/m3 SD: 372.7 in Korogocho and 82.2 µg/m3 SD: 249.9 in Viwandani, and in households using charcoal (126.5 µg/m3 SD: 434.7 in Korogocho and 75.7 µg/m3 SD: 323.0 in Viwandani. Overall, the mean PM2.5 levels measured within homes at both sites (Korogocho = 108.9 µg/m3 SD: 371.2; Viwandani = 59.3 µg/m3 SD: 234.1 were high. Residents of the two slums are exposed to high levels of PM2.5 in their homes. We recommend interventions, especially those focusing on clean cookstoves and lighting fuels to mitigate indoor levels of fine particles.

Levels of PM2.5/PM10 and associated metal(loid)s in rural households of Henan Province, China.

Science.gov (United States)

Wu, Fuyong; Wang, Wei; Man, Yu Bon; Chan, Chuen Yu; Liu, Wenxin; Tao, Shu; Wong, Ming Hung

2015-04-15

Although a majority of China's rural residents use solid fuels (biomass and coal) for household cooking and heating, clean energy such as electricity and liquid petroleum gas is becoming more popular in the rural area. Unfortunately, both solid fuels and clean energy could result in indoor air pollution. Daily respirable particulate matter (PM≤10 μm) and inhalable particulate matter (PM≤2.5 μm) were investigated in kitchens, sitting rooms and outdoor area in rural Henan during autumn (Sep to Oct 2012) and winter (Jan 2013). The results showed that PM (PM2.5 and PM10) and associated metal(loid)s varied among the two seasons and the four types of domestic energy used. Mean concentrations of PM2.5 and PM10 in kitchens during winter were 59.2-140.4% and 30.5-145.1% higher than those during autumn, respectively. Similar with the trends of PM2.5 and PM10, concentrations of As, Pb, Zn, Cd, Cu, Ni and Mn in household PM2.5 and PM10 were apparently higher in winter than those in autumn. The highest mean concentrations of PM2.5 and PM10 (368.5 and 588.7 μg m(-3)) were recorded in sitting rooms in Baofeng during winter, which were 5.7 and 3.9 times of corresponding health based guidelines for PM2.5 and PM10, respectively. Using coal can result in severe indoor air pollutants including PM and associated metal(loid)s compared with using crop residues, electricity and gas in rural Henan Province. Rural residents' exposure to PM2.5 and PM10 would be roughly reduced by 13.5-22.2% and 8.9-37.7% via replacing coal or crop residues with electricity. The present study suggested that increased use of electricity as domestic energy would effectively improve indoor air quality in rural China. Copyright © 2015 Elsevier B.V. All rights reserved.

Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building

Energy Technology Data Exchange (ETDEWEB)

Ni Honggang; Cao Shanping; Chang Wenjing [Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055 (China); Zeng Hui, E-mail: huizeng0608@gmail.com [Shenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055 (China); Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

2011-07-15

This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM{sub 2.5} (Particulate Matter up to 2.5 {mu}m in size) bounded {Sigma}{sub 15}PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM{sub 10} (Particulate Matter up to 10 {mu}m in size) bounded {Sigma}{sub 15}PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of {Sigma}{sub 15}PBDEs via dust inhalation and ingestion for adults reached {approx}141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones. - Highlights: > Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than that in the old ones. > PBDE emissions from indoor sources can be expected to continue for a long time as the PBDE-containing products in offices were to be kept many years. > The household consumer products, especially computers, are the main sources of PBDEs in central air conditioner filter dust. > Further studies are needed to fully understand the emission mechanism of PBDE from indoor consumer products. - PBDEs in central air conditioner filter dust from a new building were investigated

Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building

International Nuclear Information System (INIS)

Ni Honggang; Cao Shanping; Chang Wenjing; Zeng Hui

2011-01-01

This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM 2.5 (Particulate Matter up to 2.5 μm in size) bounded Σ 15 PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM 10 (Particulate Matter up to 10 μm in size) bounded Σ 15 PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of Σ 15 PBDEs via dust inhalation and ingestion for adults reached ∼141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones. - Highlights: → Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than that in the old ones. → PBDE emissions from indoor sources can be expected to continue for a long time as the PBDE-containing products in offices were to be kept many years. → The household consumer products, especially computers, are the main sources of PBDEs in central air conditioner filter dust. → Further studies are needed to fully understand the emission mechanism of PBDE from indoor consumer products. - PBDEs in central air conditioner filter dust from a new building were investigated

A study on the optimal design of a cyclone system for vacuum cleaner with the consideration of house dust

International Nuclear Information System (INIS)

Ha, Gun Ho; Kim, Eung Dal; Kim, Young Soo; Lee, Jae Keun; Ahn, Young Chull; Kim, Dong Gyu

2011-01-01

Cyclone, a type of particle collector widely used in the field of ambient sampling and industrial particulate control, is the principal type of gas-solids separator that use a centrifugal force. The goal of this study is to transform conventional cyclone into a new type of cyclone that can be used for the household vacuum cleaners. To meet the goal, first, the analysis about local environment and dust is carried out. Second, it must have enough high-efficiency not to reduce suction power due to clogging of exhaust filter unit. Two single cyclones with central-hopper-dust-outlet and side-wall-dust-outlet and a twin cyclone are designed and fabricated to evaluate, and compare, their dust collection efficiencies and pressure drops. The measurements of separation efficiency for dust by using DMT test dust type 08 are carried out. House dust experiment is additionally performed to check the local matters applicability such as tissue papers, fur and hairs. The collection efficiency of the twin cyclone is found to be 3-6% greater than those of two single cyclones with the same body diameter, inlet and inner cylinder diameter. Twin cyclone with a large body diameter, a small inner cylinder diameter, a short inner cylinder, a narrow inlet has high separation efficiency. This result indicates the possibility of achieving higher collection efficiencies with a twin cyclone

Health effects from exposure to atmospheric mineral dust near Las Vegas, NV, USA

Directory of Open Access Journals (Sweden)

Deborah E. Keil

Full Text Available Desert areas are usually characterized by a continuous deposition of fine airborne particles. Over time, this process results in the accumulation of silt and clay on desert surfaces. We evaluated health effects associated with regional atmospheric dust, or geogenic dust, deposited on surfaces in the Nellis Dunes Recreation Area (NDRA in Clark County, Nevada, a popular off-road vehicle (ORV recreational site frequented daily by riders, families, and day campers. Because of atmospheric mixing and the mostly regional origin of the accumulated particles, the re-suspended airborne dust is composed of a complex mixture of minerals and metals including aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Geogenic dust with a median diameter of 4.1 μm was administered via oropharyngeal aspiration to female B6C3F1 mice at doses of 0.01 to 100 mg dust/kg body weight, four times, a week apart, for 28-days. Immuno- and neurotoxicological outcomes 24 h following the last exposure were evaluated. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100 mg/kg/day. Splenic and thymic lymphocytic subpopulations and natural killer cell activity also were significantly reduced. Antibodies against MBP, NF-68, and GFAP were not affected, while brain CD3+ T cells were decreased in number. A lowest observed adverse effect level (LOAEL of 0.1 mg/kg/day and a no observed adverse effect level (NOAEL of 0.01 mg/kg/day were derived based on the antigen-specific IgM responses. Keywords: Geogenic dust, Heavy metals, Minerals, Lung exposure, Immunotoxicity, Neurotoxicity

Toxicity of Depleted Uranium Dust Particles: Results of a New Model

International Nuclear Information System (INIS)

Zucchetti, M.

2013-01-01

Depleted uranium (DU) is mostly composed of U-238, a naturally radioactive isotope. Concerning chemical toxicity, uranium, being a heavy metal, is known to have toxic effects on specific organs in the body, the kidneys in particular. Its effects are similar to those of other heavy metals, such as lead and cadmium. Scientific evidence resulting both from in vitro and in vivo analyses shows that current models of the mechanisms of toxicity of uranium dust are not fully satisfactory. They should be refined in order to obtain more effective responses and predictions regarding health effects. In particular, radiotoxicity potential of Depleted Uranium dust originated by military use of this material for ammunition must be re-evaluated taking into account the bystander effect, the dose enhancing effect and other minor phenomena. Uranium dust has both chemical and radiological toxicity: the synergistic aspect of the two effects has to be accounted for, in order to arrive to a complete description of the phenomenon. The combination of the two different toxicities (chemical and radiological) of depleted uranium is attempted here for the first time, approaching the long-term effects of Depleted Uranium, and in particular the carcinogenetic effects. A case study (Balkan war, 1999) is discussed. (Author)

Household Chemical Emergencies

Science.gov (United States)

... Content Home Be Informed Household Chemical Emergencies Household Chemical Emergencies Although the risk of a chemical accident ... reduce the risk of injury. Before a Household Chemical Emergency It is critical to store household chemicals ...

DUST AND GAS IN THE MAGELLANIC CLOUDS FROM THE HERITAGE HERSCHEL KEY PROJECT. II. GAS-TO-DUST RATIO VARIATIONS ACROSS INTERSTELLAR MEDIUM PHASES

International Nuclear Information System (INIS)

Roman-Duval, Julia; Gordon, Karl D.; Meixner, Margaret; Bot, Caroline; Bolatto, Alberto; Jameson, Katherine; Hughes, Annie; Hony, Sacha; Wong, Tony; Babler, Brian; Bernard, Jean-Philippe; Clayton, Geoffrey C.; Fukui, Yasuo; Galametz, Maud; Galliano, Frederic; Lebouteiller, Vianney; Lee, Min-Young; Glover, Simon; Israel, Frank; Li, Aigen

2014-01-01

The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and lifecycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and Hα observations. In the diffuse atomic interstellar medium (ISM), we derive the GDR as the slope of the dust-gas relation and find GDRs of 380 −130 +250 ± 3 in the LMC, and 1200 −420 +1600 ± 120 in the SMC, not including helium. The atomic-to-molecular transition is located at dust surface densities of 0.05 M ☉  pc –2 in the LMC and 0.03 M ☉  pc –2 in the SMC, corresponding to A V ∼ 0.4 and 0.2, respectively. We investigate the range of CO-to-H 2 conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on X CO to be 6 × 10 20  cm –2  K –1  km –1 s in the LMC (Z = 0.5 Z ☉ ) at 15 pc resolution, and 4 × 10 21  cm –2  K –1  km –1 s in the SMC (Z = 0.2 Z ☉ ) at 45 pc resolution. In the LMC, the slope of the dust-gas relation in the dense ISM is lower than in the diffuse ISM by a factor ∼2, even after accounting for the effects of CO-dark H 2 in the translucent envelopes of molecular clouds. Coagulation of dust grains and the subsequent dust emissivity increase in molecular clouds, and/or accretion of gas-phase metals onto dust grains, and the subsequent dust abundance (dust-to-gas ratio) increase in molecular clouds could explain the observations. In the SMC, variations in the dust-gas slope caused by coagulation or accretion are degenerate with the effects of CO-dark H 2 . Within the expected 5-20 times Galactic X CO range, the dust-gas slope can be either constant or decrease by a factor of several across ISM phases. Further modeling and observations are required to break the degeneracy between dust grain coagulation, accretion, and CO-dark H 2

THE CHEMISTRY OF POPULATION III SUPERNOVA EJECTA. II. THE NUCLEATION OF MOLECULAR CLUSTERS AS A DIAGNOSTIC FOR DUST IN THE EARLY UNIVERSE

International Nuclear Information System (INIS)

Cherchneff, Isabelle; Dwek, Eli

2010-01-01

We study the formation of molecular precursors to dust in the ejecta of Population III supernovae (Pop. III SNe) using a chemical kinetic approach to follow the evolution of small dust cluster abundances from day 100 to day 1000 after explosion. Our work focuses on zero-metallicity 20 M sun and 170 M sun progenitors, and we consider fully macroscopically mixed and unmixed ejecta. The dust precursors comprise molecular chains, rings, and small clusters of chemical composition relevant to the initial elemental composition of the ejecta under study. The nucleation stage for small silica, metal oxides and sulfides, pure metal, and carbon clusters is described with a new chemical reaction network highly relevant to the kinetic description of dust formation in hot circumstellar environments. We consider the effect of the pressure dependence of critical nucleation rates and test the impact of microscopically mixed He + on carbon dust formation. Two cases of metal depletion on silica clusters (full and no depletion) are considered to derive upper limits to the amounts of dust produced in SN ejecta at 1000 days, while the chemical composition of clusters gives a prescription for the type of dust formed in Pop. III SNe. We show that the cluster mass produced in the fully mixed ejecta of a 170 M sun progenitor is ∼ 25 M sun whereas its 20 M sun counterpart forms ∼ 0.16 M sun of clusters. The unmixed ejecta of a 170 M sun progenitor SN synthesize ∼5.6 M sun of small clusters, while its 20 M sun counterpart produces ∼0.103 M sun . Our results point to smaller amounts of dust formed in the ejecta of Pop. III SNe by a factor of ∼ 5 compared to values derived by previous studies, and to different dust chemical compositions. Such deviations result from some erroneous assumptions made, the inappropriate use of classical nucleation theory to model dust formation, and the omission of the synthesis of molecules in SN ejecta. We also find that the unmixed ejecta of massive Pop

Dust emissions eliminated in pneumatic harvesting

International Nuclear Information System (INIS)

Kallio, M.

1998-01-01

Pneumatic harvesting is the most efficient milled peat production method in unsteady weather conditions. In good summers, the best contractors harvest more than 1 000 m 3 /ha milled peat from suitable production fields. The greatest problem of the method is caused by dust emissions, in particular in fields close to settled areas. About 15 % of Finland's present peat production is collected using pneumatic harvesters. A pneumatic harvester with smaller dust emissions has been developed by VTT Energy and Vapo Oy. The wagon is based on two-stage separation of peat. The main part of the coarser milled peat is first separated, e.g. in a settling chamber, and fine dry peat dust in correctly dimensioned side by side cyclones. The first series of pneumatic harvesters based on the new separation technology was employed in summer 1996. Besides decreasing the dust emissions the harvesting capacity of the new equipment was increased. The collection capacity of the pneumatic harvester can be made more effective by enlarging the container size, be decreasing the weight, by increasing the driving speed and by developing the suction capacity. Using lighter and durable construction materials combined with advanced design lighter and stronger pneumatic harvesters have been constructed. Nozzles and their mounting have also been developed. In the improvement of nozzles, the former studies with pneumatic simulator of VTT Energy, have been of great help. Studies with the pneumatic simulator and field conditions have been made in collaboration with Turveruukki Oy, Turvemetalli Oy, Raussin Metalli Oy and Vapo Oy, as well as VNIITP of St. Petersburg, Russia

PM10 composition during an intense Saharan dust transport event over Athens (Greece)

International Nuclear Information System (INIS)

Remoundaki, E.; Bourliva, A.; Kokkalis, P.; Mamouri, R.E.; Papayannis, A.; Grigoratos, T.; Samara, C.; Tsezos, M.

2011-01-01

The influence of Saharan dust on the air quality of Southern European big cities became a priority during the last decade. The present study reports results on PM 10 monitored at an urban site at 14 m above ground level during an intense Saharan dust transport event. The elemental composition was determined by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) for 12 elements: Si, Al, Fe, K, Ca, Mg, Ti, S, Ni, Cu, Zn and Mn. PM 10 concentrations exceeded the EU limit (50 μg/m 3 ) several times during the sampling period. Simultaneous maxima have been observed for the elements of crustal origin. The concentrations of all the elements presented a common maximum, corresponding to the date where the atmosphere was heavily charged with particulate matter permanently for an interval of about 10 h. Sulfur and heavy metal concentrations were also associated to local emissions. Mineral dust represented the largest fraction of PM 10 reaching 79%. Seven days back trajectories have shown that the air masses arriving over Athens, originated from Western Sahara. Scanning Electron Microscopy coupled with Energy Dispersive X-ray analysis (SEM-EDX) revealed that particle agglomerates were abundant, most of them having sizes < 2 μm. Aluminosilicates were predominant in dust particles also rich in calcium which was distributed between calcite, dolomite, gypsum and Ca-Si particles. These results were consistent with the origin of the dust particles and the elemental composition results. Sulfur and heavy metals were associated to very fine particles < 1 μm. - Highlights: → The paper focuses on the contribution of Saharan dust in PM10 levels at an urban site. → High Ca and Fe, calcite, illite and smectites and poor quartz contents are related to source-regions. → The data sets presented are in very good agreement and are also strongly confirmed by literature. → Dust contribution in PM10 can be of comparable importance for both an urban and a remote location. �

Distortion of the microwave background by dust

International Nuclear Information System (INIS)

Rowan-Robinson, M.

1981-01-01

The Woody and Richards distortion of the microwave background has a natural explanation within the framework of the isothermal density fluctuation picture. A pregalactic generation of ''stars'' makes light and metals. The latter are able to condense into dust grains at a redshift approximately 150-225, which then absorb the starlight and reradiate it in the infrared. At the present epoch we see this emission redshifted into the millimetre range of the spectrum

Demonstration of a dust control system for boom-type roadheader. Open-file report September 1979-July 1981

International Nuclear Information System (INIS)

Burnett, M.; Pokora, R.J.; Muldoon, T.

1981-09-01

This program was initiated by the Bureau of Mines to quantify the respirable dust problem caused by the use of roadheaders in underground metal-nonmetal mines with special emphasis on this problem in uranium mines. The objective was to develop methods or equipment to alleviate respirable dust and to implement a solution in a mine. Attempts to quantify the dust problem were made by a survey of MSHA records, a survey of State nine enforcement agencies, a survey of mine records, and dust measurements taken at two mines using roadheaders. The results are not conclusive because of limited and sometimes less than useful data; however, the study does indicate that a serious dust problem could and may exist. The report discusses the available data concerning respirable dust problems and presents a solution that can potentially help to solve the problem. The solution requires the use of blowing ventilation, onboard dust extraction at the source, filtration, and continued continued use of water sprays

Dust extinction in the first galaxies

Science.gov (United States)

Jaacks, Jason; Finkelstein, Steven L.; Bromm, Volker

2018-04-01

Using cosmological volume simulations and a custom built sub-grid model for Population III (Pop III) star formation, we examine the baseline dust extinction in the first galaxies due to Pop III metal enrichment in the first billion years of cosmic history. We find that although the most enriched, high-density lines of sight in primordial galaxies can experience a measurable amount of extinction from Pop III dust [E(B - V)max = 0.07, AV, max ≈ 0.28], the average extinction is very low with ≲ 10-3. We derive a power-law relationship between dark matter halo mass and extinction of E(B-V)∝ M_halo^{0.80}. Performing a Monte Carlo parameter study, we establish the baseline reddening of the ultraviolet spectra of dwarf galaxies at high redshift due to Pop III enrichment only. With this method, we find - 2.51 ± 0.07, which is both nearly halo mass and redshift independent.

Dust Measurements in Tokamaks

International Nuclear Information System (INIS)

Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

2008-01-01

Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 (micro)m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics

Lunar Airborne Dust Toxicity Hazard Assessments (Invited)

Science.gov (United States)

Cooper, B. L.; McKay, D. S.; Taylor, L. A.; Wallace, W. T.; James, J.; Riofrio, L.; Gonzalez, C. P.

2009-12-01

The Lunar Airborne Dust Toxicity Assessment Group (LADTAG) is developing data to set the permissible limits for human exposure to lunar dust. This standard will guide the design of airlocks and ports for EVA, as well as the requirements for filtering and monitoring the atmosphere in habitable vehicles, rovers and other modules. LADTAG’s recommendation for permissible exposure limits will be delivered to the Constellation Program in late 2010. The current worst-case exposure limit of 0.05 mg/m3, estimated by LADTAG in 2006, reflects the concern that lunar dust may be as toxic as quartz dust. Freshly-ground quartz is known to be more toxic than un-ground quartz dust. Our research has shown that the surfaces of lunar soil grains can be more readily activated by grinding than quartz. Activation was measured by the amount of free radicals generated—activated simulants generate Reactive Oxygen Species (ROS) i.e., production of hydroxyl free radicals. Of the various influences in the lunar environment, micrometeorite bombardment probably creates the most long-lasting reactivity on the surfaces of grains, although solar wind impingement and short-wavelength UV radiation also contribute. The comminution process creates fractured surfaces with unsatisfied bonds. When these grains are inhaled and carried into the lungs, they will react with lung surfactant and cells, potentially causing tissue damage and disease. Tests on lunar simulants have shown that dissolution and leaching of metals can occur when the grains are exposed to water—the primary component of lung fluid. However, simulants may behave differently than actual lunar soils. Rodent toxicity testing will be done using the respirable fraction of actual lunar soils (particles with physical size of less than 2.5 micrometers). We are currently separating the fine material from the coarser material that comprises >95% of the mass of each soil sample. Dry sieving is not practical in this size range, so a new system

DUST AND GAS IN THE MAGELLANIC CLOUDS FROM THE HERITAGE HERSCHEL KEY PROJECT. I. DUST PROPERTIES AND INSIGHTS INTO THE ORIGIN OF THE SUBMILLIMETER EXCESS EMISSION

Energy Technology Data Exchange (ETDEWEB)

Gordon, Karl D.; Roman-Duval, Julia; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bot, Caroline [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l Université, F-67000 Strasbourg (France); Babler, Brian [Department of Astronomy, 475 North Charter Street, University of Wisconsin, Madison, WI 53706 (United States); Bernard, Jean-Philippe [CESR, Université de Toulouse, UPS, 9 Avenue du Colonel Roche, F-31028 Toulouse, Cedex 4 (France); Bolatto, Alberto; Jameson, Katherine [Department of Astronomy, Lab for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Boyer, Martha L. [Observational Cosmology Lab, Code 665, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Clayton, Geoffrey C. [Department of Physics and Astronomy, Louisiana State University, 233-A Nicholson Hall, Tower Drive, Baton Rouge, LA 70803 (United States); Engelbracht, Charles [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Fukui, Yasuo [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Galametz, Maud [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching-bei-Mnchen (Germany); Galliano, Frederic; Hony, Sacha; Lebouteiller, Vianney [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Hughes, Annie [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Indebetouw, Remy [Department of Astronomy, University of Virginia, and National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Israel, Frank P. [Sterrewacht Leiden, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Kawamura, Akiko [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588 (Japan); and others

2014-12-20

The dust properties in the Large and Small Magellanic clouds (LMC/SMC) are studied using the HERITAGE Herschel Key Project photometric data in five bands from 100 to 500 μm. Three simple models of dust emission were fit to the observations: a single temperature blackbody modified by a power-law emissivity (SMBB), a single temperature blackbody modified by a broken power-law emissivity (BEMBB), and two blackbodies with different temperatures, both modified by the same power-law emissivity (TTMBB). Using these models, we investigate the origin of the submillimeter excess, defined as the submillimeter emission above that expected from SMBB models fit to observations <200 μm. We find that the BEMBB model produces the lowest fit residuals with pixel-averaged 500 μm submillimeter excesses of 27% and 43% for the LMC and SMC, respectively. Adopting gas masses from previous works, the gas-to-dust ratios calculated from our fitting results show that the TTMBB fits require significantly more dust than are available even if all the metals present in the interstellar medium (ISM) were condensed into dust. This indicates that the submillimeter excess is more likely to be due to emissivity variations than a second population of colder dust. We derive integrated dust masses of (7.3 ± 1.7) × 10{sup 5} and (8.3 ± 2.1) × 10{sup 4} M {sub ☉} for the LMC and SMC, respectively. We find significant correlations between the submillimeter excess and other dust properties; further work is needed to determine the relative contributions of fitting noise and ISM physics to the correlations.

Determination and human exposure assessment of polybrominated diphenyl ethers and tetrabromobisphenol A in indoor dust in South Africa.

Science.gov (United States)

Abafe, Ovokeroye A; Martincigh, Bice S

2016-04-01

The concentration of TBBPA in dust samples from automobiles (n = 14), computer laboratories (n = 8), homes (n = 7), and offices (n = 7), and, also, PBDE concentrations in the indoor dust of 19 personal and previously owned automobiles in Durban, South Africa, were determined. Gas chromatography coupled with mass spectrometry was applied for the separation, identification, and quantitation of TBBPA and PBDEs. The median concentrations of TBBPA were 1156, 269, 120, and 492 ng g(-1) in automobiles, computer laboratories, homes, and offices, respectively. The ∑ n = 8 PBDE in 19 automobile samples ranged from 573 to 11,833 ng g(-1). BDE-209 accounted for approximately 42% of ∑ n = 8 PBDE in the samples. Household characteristics influenced the distribution of TBBPA in the various microenvironments. By assuming an average dust ingestion rate, and a median TBBPA concentration, the ∑DED (in ng kg(-1) bw day(-1)) of TBBPA is 0.08, 0.08, and 0.60, for an adult, teenager, and toddler, respectively. These doses are similar to dust ingestion intakes reported for Asian countries where there is a high demand for TBBPA as a flame retardant. Similarly, automobiles provide ample opportunity for human exposure to PBDEs via dust ingestion, particularly for toddlers and occupationally exposed adults.

Variation of rock-forming metals in sub-annual increments of modern Greenland snow

Science.gov (United States)

Hinkley, T.K.

1992-01-01

Modern snowpack from central south Greenland was sampled in sub-seasonal increments and analysed for a suite of major, minor and trace rock-forming metals (K, Rb, Cs, Ca, Sr, Ba). There is a sharp seasonal concentration maximum for all six metals that comes in summer, later than mid-June. Metal concentrations in all other parts of the year's snowpack are up to 10 or more times smaller. The concentration maximum is preceded by low values in autumn-winter, very low values in early-mid-spring, and moderate-to-high values in late spring early summer; this pattern is seen consistently in three separate time stratigraphic intervals representing the same seasonal periods, spanning the time interval 1981-1984. The absolute concentration values of the snow strata representing the low-concentration portion of the year, autumn-winter-spring, may vary substantially from year to year, by a factor of two, or more. The finding that all rock-forming metals are at a sharp concentration maximum in late summer contrasts with the interpretations of several other studies in high-latitude northern regions. Those studies have reported a broad maximum of continental dust-associated metals in late winter and spring. However samples of the other studies have mostly come from regions farther to the north, and the analyses have emphasized industrial pollutant metals rather than the matched rock-forming suite of the present study. The metals measured were chosen to give information about the origin and identity of the rock and soil dusts, and sea salts, present as impurities in the snow. Metal ratios indicate that the dusts in the snowpacks are of continental origin and from ferromagnesian rocks. Source rock types for dusts in central south Greenland snow contrast with the felsic rock dusts of the Sierra Nevada, CA, annual snowpacks, and with the very felsic rock dusts in large south central Alaskan mountain glaciers. Samples in which masses of sea salt are much larger than those of rock dusts

Dust confinement and dust acoustic waves in a magnetized plasma

Science.gov (United States)

Piel, A.

2005-10-01

Systematic laboratory experiments on dust acoustic waves require the confinement of dust particles. Here we report on new experiments in a magnetized plasma region in front of an additional positively biased disk electrode in a background plasma which is generated in argon at 27MHz between a disk and grid electrode. The plasma diffuses through the grid along the magnetic field. The three-dimensional dust distribution is measured with a horizontal sheet of laser light and a CCD camera, which are mounted on a vertical translation stage. Depending on magnetic field and discharge current, cigar or donut-shaped dust clouds are generated, which tend to rotate about the magnetic field direction. Measurements with emissive probes show that the axial confinement of dust particles with diameters between 0.7-2 μm is achieved by a balance of ion-drag force and electric field force. Dust levitation and radial confinement is due to a strong radial electric field. Dust acoustic waves are destabilized by the ion flow or can be stimulated by a periodic bias on the disk electrode. The observed wave dispersion is compared with fluid and kinetic models of the dust acoustic wave.

Exposure to dust-bound PAHs and associated carcinogenic risk in primitive and traditional cooking practices in Pakistan.

Science.gov (United States)

Kamal, Atif; Malik, Riffat Naseem; Martellini, Tania; Cincinelli, Alessandra

2015-08-01

The aim of this study was to determine the abundance and distribution of polycyclic aromatic hydrocarbons (PAHs) in dust samples collected from the selected professional cooking workplaces (WCs) and residential household cooking areas (WRs), where traditional and primitive cooking practices are still prevelent. Another aim of this study was to investigate the carcinogenic risk for Pakistani human exposure to dust-bound PAHs via the routes of inhalation, ingestion, and dermal contact. Generally, the concentration of individual congeners of PAHs in surface dust samples of WC sites was higher than those measured in WR sites (p < 0.05). The benzo(a)pyrene (B(a)P), a very high carcinogenic compound, was present in the dust samples from WC sites in the highest mean concentration (630 ng g(-1) dry weight (d.w.)). The BaP mean concentration in WC workplaces was almost eight times higher than the mean value found in WR exposure sites. Moreover, the average concentration of ∑PAHs, combustion origin PAHs (∑COMB) and sum total of 7-carcinogenic PAHs (∑7-carcinogens) were also significantly higher in WC dusts samples than that in WR workplaces. Principal component analysis (PCA) and diagnostic ratios suggested coal/wood combustion as major PAH emission sources in both exposure sites. The average incremental lifetime cancer risk (ILCR) suggested a moderate to potential high cancer risk for adults and children exposed to dust-bound PAHs in both exposure sites, in particular via both dermal and ingestion contact pathways.

Allergies, asthma, and dust

Science.gov (United States)

Reactive airway disease - dust; Bronchial asthma - dust; Triggers - dust ... Things that make allergies or asthma worse are called triggers. Dust is a common trigger. When your asthma or allergies become worse due to dust, you are ...

THE DUST PROPERTIES OF z {approx} 3 MIPS-LBGs FROM PHOTOCHEMICAL MODELS

Energy Technology Data Exchange (ETDEWEB)

Fan, X. L. [School of Physics and Electronics Information, Hubei University of Education, 430205 Wuhan (China); Pipino, A. [Institut fur Astronomie, ETH Zurich, CH-8093 Zurich (Switzerland); Matteucci, F., E-mail: fan@oats.inaf.it [Dipartimento di Fisica, Sezione di Astronomia, Universit a di Trieste, via G.B. Tiepolo 11, I-34131 Trieste (Italy)

2013-05-10

The stacked spectral energy distribution (SED) 24 {mu}m Lyman break galaxies (MIPS-LBGs) detected by the Multiband Imaging Photometer for Spitzer (MIPS) is fitted by means of the spectrophotometric model GRASIL with an ''educated'' fitting approach which benefits from the results of chemical evolution models. The star formation rate-age-metallicity degeneracies of SED modeling are broken by using star formation history (SFH) and chemical enrichment history suggested by chemical models. The dust mass, dust abundance, and chemical pattern of elements locked in the dust component are also directly provided by chemical models. Using our new ''fitting'' approach, we derive the total mass M{sub tot}, stellar mass M{sub *}, gas mass M{sub g} , dust mass M{sub d} , age, and star formation rate (SFR) of the stacked MIPS-LBG in a self-consistent way. Our estimate of M{sub *} = 8 Multiplication-Sign 10{sup 10} of the stacked MIPS-LBG agrees with other works based on UV-optical SED fitting. We suggest that the MIPS-LBGs at z {approx} 3 are young (0.3-0.6 Gyr), massive (M{sub tot} {approx} 10{sup 11} M{sub Sun }), dusty (M{sub d} {approx} 10{sup 8} M{sub Sun }), and metal-rich (Z {approx} Z{sub Sun }) progenitors of elliptical galaxies undergoing a strong burst of star formation (SFR {approx} 200 M{sub Sun} yr{sup -1}). Our estimate of M{sub d} = 7 Multiplication-Sign 10{sup 7} M{sub Sun} of the stacked MIPS-LBG is about a factor of eight lower than the estimated value based on single temperature graybody fitting, suggesting that self-consistent SED models are needed to estimate dust mass. By comparing with Milky Way molecular cloud and dust properties, we suggest that denser and dustier environments and flatter dust size distribution are likely in high-redshift massive star-forming galaxies. These dust properties, as well as the different types of SFHs, can cause different SED shapes between high-redshift star-forming ellipticals and

Analysis of Dust and Fission Products in PBMR Turbine

International Nuclear Information System (INIS)

Stempniewicz, M.M.; Wessels, D.

2014-01-01

A 400 MWth direct cycle Pebble Bed Modular reactor was under development in South Africa. The work performed included design and safety analyses. In HTR/PBMR, graphite dust is generated during normal reactor operation due to pebble-to-pebble scratching. This dust will be deposited throughout the primary system. Furthermore, the dust will become radioactive due to sorption of fission products released, although in very small quantities, during normal operation. This paper presents a model and analyses of the PBMR turbine with the SPECTRA code. The purpose of the present work was to estimate the amount and distribution of deposited dust and the fission products, namely cesium, iodine, and silver, during plant life-time, which was assumed to be 40 full-power years. The performed work showed that after 40 years of plant life-time deposited layers are very small. The largest deposition is of course observed on the dust filters. Apart from the dust filters, the largest dust deposition is observed on the: • Outer Casing (inner walls) • Turbine Rotor Cooling Cavity (inner walls) • HPC Cold Cooling Gas Header (inner walls) This is caused by relatively low gas velocities in these volumes. The low velocities allow a continuous build-up of the dust layer. About 90% of cesium, 40% of iodine, and 99.9% of silver is adsorbed on the metallic structures of the turbine. The sorption rate increases along the turbine due to decreasing temperatures. In case of cesium and iodine the highest concentrations are observed in the last stage (stage 12) of the turbine. In the case of silver the sorption is so large that the silver vapor is significantly depleted in the last stages of the turbine. This is a reason for having a maximum in silver concentration in the stage 10. In the following stages the concentration decreases due to very small silver vapor fraction in the gas. (author)

DUST AND GAS IN THE MAGELLANIC CLOUDS FROM THE HERITAGE HERSCHEL KEY PROJECT. II. GAS-TO-DUST RATIO VARIATIONS ACROSS INTERSTELLAR MEDIUM PHASES

Energy Technology Data Exchange (ETDEWEB)

Roman-Duval, Julia; Gordon, Karl D.; Meixner, Margaret [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bot, Caroline [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' université, F-67000 Strasbourg (France); Bolatto, Alberto; Jameson, Katherine [Department of Astronomy, Lab for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Hughes, Annie; Hony, Sacha [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Wong, Tony [University of Illinois at Urbana-Champaign, 1002 W. Green St., Urbana, IL 61801 (United States); Babler, Brian [Department of Astronomy, University of Wisconsin, 475 North Charter St., Madison, WI 53706 (United States); Bernard, Jean-Philippe [CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France); Clayton, Geoffrey C. [Louisiana State University, Department of Physics and Astronomy, 233-A Nicholson Hall, Tower Dr., Baton Rouge, LA 70803-4001 (United States); Fukui, Yasuo [Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Galametz, Maud [European Southern Observatory, Karl-Schwarzschild-Str 2, D-85748 Garching (Germany); Galliano, Frederic; Lebouteiller, Vianney; Lee, Min-Young [CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Glover, Simon [Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle Strasse 2, D-69120 Heidelberg (Germany); Israel, Frank [Sterrewacht Leiden, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Li, Aigen, E-mail: duval@stsci.edu [314 Physics Building, Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); and others

2014-12-20

The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and lifecycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and Hα observations. In the diffuse atomic interstellar medium (ISM), we derive the GDR as the slope of the dust-gas relation and find GDRs of 380{sub −130}{sup +250} ± 3 in the LMC, and 1200{sub −420}{sup +1600} ± 120 in the SMC, not including helium. The atomic-to-molecular transition is located at dust surface densities of 0.05 M {sub ☉} pc{sup –2} in the LMC and 0.03 M {sub ☉} pc{sup –2} in the SMC, corresponding to A {sub V} ∼ 0.4 and 0.2, respectively. We investigate the range of CO-to-H{sub 2} conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on X {sub CO} to be 6 × 10{sup 20} cm{sup –2} K{sup –1} km{sup –1} s in the LMC (Z = 0.5 Z {sub ☉}) at 15 pc resolution, and 4 × 10{sup 21} cm{sup –2} K{sup –1} km{sup –1} s in the SMC (Z = 0.2 Z {sub ☉}) at 45 pc resolution. In the LMC, the slope of the dust-gas relation in the dense ISM is lower than in the diffuse ISM by a factor ∼2, even after accounting for the effects of CO-dark H{sub 2} in the translucent envelopes of molecular clouds. Coagulation of dust grains and the subsequent dust emissivity increase in molecular clouds, and/or accretion of gas-phase metals onto dust grains, and the subsequent dust abundance (dust-to-gas ratio) increase in molecular clouds could explain the observations. In the SMC, variations in the dust-gas slope caused by coagulation or accretion are degenerate with the effects of CO-dark H{sub 2}. Within the expected 5-20 times Galactic X {sub CO} range, the dust-gas slope can be either constant or decrease by a factor of several across ISM phases. Further modeling

Platinum-Group Elements in Soils and Street Dust of the Southeastern Administrative District of Moscow

Science.gov (United States)

Ladonin, D. V.

2018-03-01

The contents of five platinum-group metals (Ru, Rh, Pd, Ir, and Pt) in soils and street dust of the Southeastern administrative district (SEAD) of Moscow have been determined. The contents of these elements in soils may considerably exceed their natural abundances in the lithosphere and are characterized by considerable variability and asymmetric frequency distribution. A close correlation between Rh, Pd, and Pt contents in soils and street dust has been shown. The data on the contents of the elements and the ratios between them suggest that motor vehicles are the major source of pollution of soils and street dust in the studied district.

PM{sub 10} composition during an intense Saharan dust transport event over Athens (Greece)

Energy Technology Data Exchange (ETDEWEB)

Remoundaki, E., E-mail: remound@metal.ntua.gr [National Technical University of Athens (NTUA), School of Mining and Metallurgical Engineering, Laboratory of Environmental Science and Engineering, Heroon Polytechniou 9, 15780 Zografou (Greece); Bourliva, A. [Aristotle University of Thessaloniki (AUTH), Department of Geology, 54124 Thessaloniki (Greece); Hellenic Open University, School of Science and Technology, 26335 Patras (Greece); Kokkalis, P.; Mamouri, R.E.; Papayannis, A. [National Technical University of Athens (NTUA), Laser Remote Sensing Laboratory, Heroon Polytechniou 9, 15780 Zografou (Greece); Grigoratos, T.; Samara, C. [Aristotle University of Thessaloniki (AUTH), Department of Chemistry, Environmental Pollution Control Laboratory, 54124 Thessaloniki (Greece); Tsezos, M. [National Technical University of Athens (NTUA), School of Mining and Metallurgical Engineering, Laboratory of Environmental Science and Engineering, Heroon Polytechniou 9, 15780 Zografou (Greece)

2011-09-15

The influence of Saharan dust on the air quality of Southern European big cities became a priority during the last decade. The present study reports results on PM{sub 10} monitored at an urban site at 14 m above ground level during an intense Saharan dust transport event. The elemental composition was determined by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) for 12 elements: Si, Al, Fe, K, Ca, Mg, Ti, S, Ni, Cu, Zn and Mn. PM{sub 10} concentrations exceeded the EU limit (50 {mu}g/m{sup 3}) several times during the sampling period. Simultaneous maxima have been observed for the elements of crustal origin. The concentrations of all the elements presented a common maximum, corresponding to the date where the atmosphere was heavily charged with particulate matter permanently for an interval of about 10 h. Sulfur and heavy metal concentrations were also associated to local emissions. Mineral dust represented the largest fraction of PM{sub 10} reaching 79%. Seven days back trajectories have shown that the air masses arriving over Athens, originated from Western Sahara. Scanning Electron Microscopy coupled with Energy Dispersive X-ray analysis (SEM-EDX) revealed that particle agglomerates were abundant, most of them having sizes < 2 {mu}m. Aluminosilicates were predominant in dust particles also rich in calcium which was distributed between calcite, dolomite, gypsum and Ca-Si particles. These results were consistent with the origin of the dust particles and the elemental composition results. Sulfur and heavy metals were associated to very fine particles < 1 {mu}m. - Highlights: {yields} The paper focuses on the contribution of Saharan dust in PM10 levels at an urban site. {yields} High Ca and Fe, calcite, illite and smectites and poor quartz contents are related to source-regions. {yields} The data sets presented are in very good agreement and are also strongly confirmed by literature. {yields} Dust contribution in PM10 can be of comparable importance for

Carbohydrate and protein contents of grain dusts in relation to dust morphology.

Science.gov (United States)

Dashek, W V; Olenchock, S A; Mayfield, J E; Wirtz, G H; Wolz, D E; Young, C A

1986-01-01

Grain dusts contain a variety of materials which are potentially hazardous to the health of workers in the grain industry. Because the characterization of grain dusts is incomplete, we are defining the botanical, chemical, and microbial contents of several grain dusts collected from grain elevators in the Duluth-Superior regions of the U.S. Here, we report certain of the carbohydrate and protein contents of dusts in relation to dust morphology. Examination of the gross morphologies of the dusts revealed that, except for corn, each dust contained either husk or pericarp (seed coat in the case of flax) fragments in addition to respirable particles. When viewed with the light microscope, the fragments appeared as elongated, pointed structures. The possibility that certain of the fragments within corn, settled, and spring wheat were derived from cell walls was suggested by the detection of pentoses following colorimetric assay of neutralized 2 N trifluoroacetic acid hydrolyzates of these dusts. The presence of pentoses together with the occurrence of proteins within water washings of grain dusts suggests that glycoproteins may be present within the dusts. With scanning electron microscopy, each dust was found to consist of a distinct assortment of particles in addition to respirable particles. Small husk fragments and "trichome-like" objects were common to all but corn dust. Images FIGURE 4. FIGURE 5. PMID:3709476

Study on simultaneous recycling of EAF dust and plastic waste containing TBBPA

International Nuclear Information System (INIS)

Grabda, Mariusz; Oleszek, Sylwia; Shibata, Etsuro; Nakamura, Takashi

2014-01-01

Highlights: • Thermal treatment of EAF dust with TBBPADGE (a constituent of epoxy resins). • High reactivity of evolved HBr gas with Zn (ZnO, ZnFe 2 O 4 ) and Pb present in EAFD. • High separation of Zn, Pb from Fe-rich residue by a bromination–evaporation process. • Complete evaporation of the formed metallic bromides from the residue at 550 °C. - Abstract: In the present work we investigated the fates of zinc, lead, and iron present in electric arc furnace dust during thermal treatment of the dust with tetrabromobisphenol A (TBBPA) and tetrabromobisphenol A diglycidyl ether (TBBPADGE). Mixtures of these materials were compressed into pellets and heated in a laboratory-scale furnace at 550 °C for 80 min, under oxidizing and inert conditions. The solid, condensed, and gaseous-phase products were characterized using an array of analytical methods: scanning electron microscopy, X-ray diffraction, electron probe microscopy, inductively coupled plasma, ion chromatography, and gas chromatography. The results indicated that heating the mixtures under specific conditions enabled high separation of zinc and lead from iron-rich residues, by a bromination–evaporation process. In the case of TBBPADGE, a maximum of 85% of zinc and 81% of lead were effectively separated under the above conditions. The process is based on the reaction between the highly reactive HBr gas evolved during thermal degradation of the flame-retarded materials with zinc (ZnO and ZnFe 2 O 4 ) and lead in the dust, followed by complete evaporation of the formed metallic bromides from the solid residue

Study on simultaneous recycling of EAF dust and plastic waste containing TBBPA

Energy Technology Data Exchange (ETDEWEB)

Grabda, Mariusz, E-mail: mariusz@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Aoba-ku, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, M. Sklodowska-Curie 34, 41-819 Zabrze (Poland); Oleszek, Sylwia [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Aoba-ku, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, M. Sklodowska-Curie 34, 41-819 Zabrze (Poland); Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Aoba-ku, Sendai 980-8577 (Japan)

2014-08-15

Highlights: • Thermal treatment of EAF dust with TBBPADGE (a constituent of epoxy resins). • High reactivity of evolved HBr gas with Zn (ZnO, ZnFe{sub 2}O{sub 4}) and Pb present in EAFD. • High separation of Zn, Pb from Fe-rich residue by a bromination–evaporation process. • Complete evaporation of the formed metallic bromides from the residue at 550 °C. - Abstract: In the present work we investigated the fates of zinc, lead, and iron present in electric arc furnace dust during thermal treatment of the dust with tetrabromobisphenol A (TBBPA) and tetrabromobisphenol A diglycidyl ether (TBBPADGE). Mixtures of these materials were compressed into pellets and heated in a laboratory-scale furnace at 550 °C for 80 min, under oxidizing and inert conditions. The solid, condensed, and gaseous-phase products were characterized using an array of analytical methods: scanning electron microscopy, X-ray diffraction, electron probe microscopy, inductively coupled plasma, ion chromatography, and gas chromatography. The results indicated that heating the mixtures under specific conditions enabled high separation of zinc and lead from iron-rich residues, by a bromination–evaporation process. In the case of TBBPADGE, a maximum of 85% of zinc and 81% of lead were effectively separated under the above conditions. The process is based on the reaction between the highly reactive HBr gas evolved during thermal degradation of the flame-retarded materials with zinc (ZnO and ZnFe{sub 2}O{sub 4}) and lead in the dust, followed by complete evaporation of the formed metallic bromides from the solid residue.

Dust Devil Tracks

Science.gov (United States)

2002-01-01

(Released 8 May 2002) The Science This image, centered near 50.0 S and 17.7 W displays dust devil tracks on the surface. Most of the lighter portions of the image likely have a thin veneer of dust settled on the surface. As a dust devil passes over the surface, it acts as a vacuum and picks up the dust, leaving the darker substrate exposed. In this image there is a general trend of many of the tracks running from east to west or west to east, indicating the general wind direction. There is often no general trend present in dust devil tracks seen in other images. The track patterns are quite ephemeral and can completely change or even disappear over the course of a few months. Dust devils are one of the mechanisms that Mars uses to constantly pump dust into the ubiquitously dusty atmosphere. This atmospheric dust is one of the main driving forces of the present Martian climate. The Story Vrrrrooooooooom. Think of a tornado, the cartoon Tasmanian devil, or any number of vacuum commercials that powerfully suck up swirls of dust and dirt. That's pretty much what it's like on the surface of Mars a lot of the time. Whirlpools of wind called

Plastics from household waste as a source of heavy metal pollution: An inventory study using INAA as the analytical technique

International Nuclear Information System (INIS)

Bode, P.; De Bruin, M.; Aalbers, Th.G.; Meyer, P.J.

1990-01-01

An inventory study to the levels of cadmium in the plastic component of household waste was carried out utilizing INAA as the analytical technique. In a 2-h irradiation, 2-d decay, and 1-h measurement, protocol adequate sensitivities could be obtained for Cd, but also for a group of other metals: Cr, Co, Ni, Cu, Sr, Zn, As, Se, Mo, Sn, Sb, Ba, and Hg. Red-, orange-, and yellow-colored plastics either contain Cd at high levels (over 1000 mg/kg) or have relatively low Cd concentrations (<50 mg/kg). High concentrations were also occasionally found for Sr,Se,Ba,Sb, and Hg. INAA appeared very well to be routinely usable for such analysis because of the absence of a destruction step, adequate sensitivity, high accuracy, and multielement results

Connecting the Interstellar Gas and Dust Properties in Distant Galaxies Using Quasar Absorption Systems

Science.gov (United States)

Aller, Monique C.; Dwek, Eliahu; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam; Lackey, Kyle; Dwek, Eli; Beiranvand, Nassim;

THE FIRST PLANETS: THE CRITICAL METALLICITY FOR PLANET FORMATION

International Nuclear Information System (INIS)

Johnson, Jarrett L.; Li Hui

2012-01-01

A rapidly growing body of observational results suggests that planet formation takes place preferentially at high metallicity. In the core accretion model of planet formation this is expected because heavy elements are needed to form the dust grains which settle into the midplane of the protoplanetary disk and coagulate to form the planetesimals from which planetary cores are assembled. As well, there is observational evidence that the lifetimes of circumstellar disks are shorter at lower metallicities, likely due to greater susceptibility to photoevaporation. Here we estimate the minimum metallicity for planet formation, by comparing the timescale for dust grain growth and settling to that for disk photoevaporation. For a wide range of circumstellar disk models and dust grain properties, we find that the critical metallicity above which planets can form is a function of the distance r at which the planet orbits its host star. With the iron abundance relative to that of the Sun [Fe/H] as a proxy for the metallicity, we estimate a lower limit for the critical abundance for planet formation of [Fe/H] crit ≅ –1.5 + log (r/1 AU), where an astronomical unit (AU) is the distance between the Earth and the Sun. This prediction is in agreement with the available observational data, and carries implications for the properties of the first planets and for the emergence of life in the early universe. In particular, it implies that the first Earth-like planets likely formed from circumstellar disks with metallicities Z ∼> 0.1 Z ☉ . If planets are found to orbit stars with metallicities below the critical metallicity, this may be a strong challenge to the core accretion model.

Characterization of electric arc furnace dust aiming reuse; Caracterizacao da poeira de aciaria eletrica visando o seu reaproveitamento

Energy Technology Data Exchange (ETDEWEB)

Grillo, F.F.; Oliveira, E.B.G.; Oliveira, J.R. de, E-mail: fgrillo@ifes.edu.b [Instituto Federal de Ciencia e Tecnologia do Espirito Santo (IFES), Vitoria, ES (Brazil); Telles, V.B.; Tenorio, J.A.S. [Universidade de Sao Paulo (USP), SP (Brazil)

2010-07-01

This work aims to study the characterize of steelmaking dust, from the primary refining of steel in Electric Arc Furnace, in order to verify feasibility of reuse through the addition of hot metal in the form of briquette. The techniques used to characterize the dust was chemical analyses, size separation tests, X-ray diffraction analyses (XRD), Scanning Electron Microscopy (SEM). After characterization, was the calculation of reductant considering the complete reduction of iron oxides and then to briquetting. The waste sample is composed essentially of spherical particles and has a very small particle size (85% below 10 {mu}m). The XRD has presented compounds such as ZnFe{sub 2}O{sub 4}, Fe{sub 3}O{sub 4}, ZnO e SiO{sub 2}. This work showed that its possible recovery approximately 92% of metal iron from dust generated during steelmaking.This (author)

Are neighborhood-level characteristics associated with indoor allergens in the household?

Science.gov (United States)

Rosenfeld, Lindsay; Rudd, Rima; Chew, Ginger L; Emmons, Karen; Acevedo-García, Dolores

2010-02-01

Individual home characteristics have been associated with indoor allergen exposure; however, the influence of neighborhood-level characteristics has not been well studied. We defined neighborhoods as community districts determined by the New York City Department of City Planning. We examined the relationship between neighborhood-level characteristics and the presence of dust mite (Der f 1), cat (Fel d 1), cockroach (Bla g 2), and mouse (MUP) allergens in the household. Using data from the Puerto Rican Asthma Project, a birth cohort of Puerto Rican children at risk of allergic sensitization (n = 261), we examined associations between neighborhood characteristics (percent tree canopy, asthma hospitalizations per 1,000 children, roadway length within 100 meters of buildings, serious housing code violations per 1000 rental units, poverty rates, and felony crime rates), and the presence of indoor allergens. Allergen cutpoints were used for categorical analyses and defined as follows: dust mite: >0.25 microg/g; cat: >1 microg/g; cockroach: >1 U/g; mouse: >1.6 microg/g. Serious housing code violations were statistically significantly positively associated with dust mite, cat, and mouse allergens (continuous variables), adjusting for mother's income and education, and all neighborhood-level characteristics. In multivariable logistic regression analyses, medium levels of housing code violations were associated with higher dust mite and cat allergens (1.81, 95%CI: 1.08, 3.03 and 3.10, 95%CI: 1.22, 7.92, respectively). A high level of serious housing code violations was associated with higher mouse allergen (2.04, 95%CI: 1.15, 3.62). A medium level of housing code violations was associated with higher cockroach allergen (3.30, 95%CI: 1.11, 9.78). Neighborhood-level characteristics, specifically housing code violations, appear to be related to indoor allergens, which may have implications for future research explorations and policy decisions.

Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia.

Science.gov (United States)

McEwen, Abigail R; Hsu-Kim, Heileen; Robins, Nicholas A; Hagan, Nicole A; Halabi, Susan; Barras, Olivo; Richter, Daniel deB; Vandenberg, John J

2016-08-15

Potosí, Bolivia, is the site of centuries of historic and present-day mining of the Cerro Rico, a mountain known for its rich polymetallic deposits, and was the site of large-scale Colonial era silver refining operations. In this study, the concentrations of several metal and metalloid elements were quantified in adobe brick, dirt floor, and surface dust samples from 49 houses in Potosí. Median concentrations of total mercury (Hg), lead (Pb), and arsenic (As) were significantly greater than concentrations measured in Sucre, Bolivia, a non-mining town, and exceeded US-based soil screening levels. Adobe brick samples were further analyzed for bioaccessible concentrations of trace elements using a simulated gastric fluid (GF) extraction. Median GF extractable concentrations of Hg, As, and Pb were 0.085, 13.9, and 32.2% of the total element concentration, respectively. Total and GF extractable concentrations of Hg, As, and Pb were used to estimate exposure and potential health risks to children following incidental ingestion of adobe brick particles. Risks were assessed using a range of potential ingestion rates (50-1000mg/day). Overall, the results of the risk assessment show that the majority of households sampled contained concentrations of bioaccessible Pb and As, but not Hg, that represent a potential health risk. Even at the lowest ingestion rate considered, the majority of households exceeded the risk threshold for Pb, indicating that the concentrations of this metal are of particular concern. To our knowledge, this is the first study to quantify key trace elements in building materials in adobe brick houses and the results indicate that these houses are a potential source of exposure to metals and metalloids in South American mining communities. Additional studies are needed to fully characterize personal exposure and to understand potential adverse health outcomes within the community. Copyright © 2016 Elsevier B.V. All rights reserved.

Kuiper Belt Dust Grains as a Source of Interplanetary Dust Particles

Science.gov (United States)

Liou, Jer-Chyi; Zook, Herbert A.; Dermott, Stanley F.

1996-01-01

The recent discovery of the so-called Kuiper belt objects has prompted the idea that these objects produce dust grains that may contribute significantly to the interplanetary dust population. In this paper, the orbital evolution of dust grains, of diameters 1 to 9 microns, that originate in the region of the Kuiper belt is studied by means of direct numerical integration. Gravitational forces of the Sun and planets, solar radiation pressure, as well as Poynting-Robertson drag and solar wind drag are included. The interactions between charged dust grains and solar magnetic field are not considered in the model. Because of the effects of drag forces, small dust grains will spiral toward the Sun once they are released from their large parent bodies. This motion leads dust grains to pass by planets as well as encounter numerous mean motion resonances associated with planets. Our results show that about 80% of the Kuiper belt grains are ejected from the Solar System by the giant planets, while the remaining 20% of the grains evolve all the way to the Sun. Surprisingly, the latter dust grains have small orbital eccentricities and inclinations when they cross the orbit of the Earth. This makes them behave more like asteroidal than cometary-type dust particles. This also enhances their chances of being captured by the Earth and makes them a possible source of the collected interplanetary dust particles; in particular, they represent a possible source that brings primitive/organic materials from the outer Solar System to the Earth. When collisions with interstellar dust grains are considered, however, Kuiper belt dust grains around 9 microns appear likely to be collisionally shattered before they can evolve toward the inner part of the Solar System. The collision destruction can be applied to Kuiper belt grains up to about 50 microns. Therefore, Kuiper belt dust grains within this range may not be a significant part of the interplanetary dust complex in the inner Solar

Simulating STARDUST: Reproducing Impacts of Interstellar Dust in the Laboratory

Science.gov (United States)

Postberg, F.; Srama, R.; Hillier, J. K.; Sestak, S.; Green, S. F.; Trieloff, M.; Grün, E.

2008-09-01

Our experiments are carried out to support the analysis of interstellar dust grains, ISDGs, brought to earth by the STARDUST mission. Since the very first investigations, it has turned out that the major problem of STARDUST particle analysis is the modification (partly even the destruction) during capture when particles impact the spacecraft collectors with a velocity of up to 20 km/s. While it is possible to identify, extract, and analyse cometary grains larger than a few microns in aerogel and on metal collector plates, the STARDUST team is not yet ready for the identification, extraction, and analysis of sub-micron sized ISDGs with impact speeds of up to 20 km/s. Reconstructing the original particle properties requires a simulation of this impact capture process. Moreover, due to the lack of laboratory studies of high speed impacts of micron scale dust into interstellar STARDUST flight spares, the selection of criteria for the identification of track candidates is entirely subjective. Simulation of such impact processes is attempted with funds of the FRONTIER program within the framework of the Heidelberg University initiative of excellence. The dust accelerator at the MPI Kernphysik is a facility unique in the world to perform such experiments. A critical point is the production of cometary and interstellar dust analogue material and its acceleration to very high speeds of 20 km/s, which has never before been performed in laboratory experiments. Up to now only conductive material was successfully accelerated by the 2 MV Van de Graaf generator of the dust accelerator facility. Typical projectile materials are Iron, Aluminium, Carbon, Copper, Silver, and the conducting hydrocarbon Latex. Ongoing research now enables the acceleration of any kind of rocky planetary and interstellar dust analogues (Hillier et al. 2008, in prep.). The first batch of dust samples produced with the new method consists of micron and submicron SiO2 grains. Those were successfully

Heavy metal movement in metal-contaminated soil profiles

Energy Technology Data Exchange (ETDEWEB)

Li, Zhenbin; Shuman, L.M. [Univ. of Georgia, Griffin, GA (United States)

1996-10-01

Heavy metal movement in soil profiles is a major environmental concern because even slow transport through the soil may eventually lead to deterioration of groundwater quality. In this study, three metal-contaminated soil (Fuquay, Dothan, and Clarendon) were selected from cropland were a high-metal flue dust had been applied annually for 6 years to raise soil pH, with application ending 4 years before sampling. One uncontaminated soil (Tifton) from the same physiographic area was also sampled as a control. Soil samples were collected in 15-cm increments from the surface to 105 cm in depth. Total contents of Zn, Cd, and Pb in the soils samples were determined. To better understand metal movement in relation to metal fractions in the soil profile, soil samples were also extracted sequentially for exchangeable (EXC), organic matter (OM), Mn oxide (MNO), amorphous Fe oxide (AFEO), crystalline Fe oxide (CFEO), and residual (RES) fractions. 35 refs., 6 figs., 2 tabs.

Whither Cometary Dust?

Science.gov (United States)

Lisse, Carey M.

2010-10-01

In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

Atmospherically deposited trace metals from bulk mineral concentrate port operations.

Science.gov (United States)

Taylor, Mark Patrick

2015-05-15

Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection. Copyright © 2015 Elsevier B.V. All rights reserved.

Integrative Analysis of Desert Dust Size and Abundance Suggests Less Dust Climate Cooling

Science.gov (United States)

Kok, Jasper F.; Ridley, David A.; Zhou, Qing; Miller, Ron L.; Zhao, Chun; Heald, Colette L.; Ward, Daniel S.; Albani, Samuel; Haustein, Karsten

2017-01-01

Desert dust aerosols affect Earths global energy balance through interactions with radiation, clouds, and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, and the climate impact of possible future alterations in dust loading is similarly disputed. Here we use an integrative analysis of dust aerosol sizes and abundance to constrain the climatic impact of dust through direct interactions with radiation. Using a combination of observational, experimental, and model data, we find that atmospheric dust is substantially coarser than represented in current climate models. Since coarse dust warms global climate, the dust direct radiative effect (DRE) is likely less cooling than the 0.4 W m superscript 2 estimated by models in a current ensemble. We constrain the dust DRE to -0.20 (-0.48 to +0.20) W m superscript 2, which suggests that the dust DRE produces only about half the cooling that current models estimate, and raises the possibility that dust DRE is actually net warming the planet.

DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

International Nuclear Information System (INIS)

Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J.

2013-01-01

We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S ν (880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S ν (880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10 11 (L ☉ ) and 4-14 × 10 7 (M ☉ ), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution

Dust Destruction in the ISM: A Re-Evaluation of Dust Lifetimes

Science.gov (United States)

Jones, A. P.; Nuth, J. A., III

2011-01-01

There is a long-standing conundrum in interstellar dust studies relating to the discrepancy between the time-scales for dust formation from evolved stars and the apparently more rapid destruction in supernova-generated shock waves. Aims. We re-examine some of the key issues relating to dust evolution and processing in the interstellar medium. Methods. We use recent and new constraints from observations, experiments, modelling and theory to re-evaluate dust formation in the interstellar medium (ISM). Results. We find that the discrepancy between the dust formation and destruction time-scales may not be as significant as has previously been assumed because of the very large uncertainties involved. Conclusions. The derived silicate dust lifetime could be compatible with its injection time-scale, given the inherent uncertainties in the dust lifetime calculation. The apparent need to re-form significant quantities of silicate dust in the tenuous interstellar medium may therefore not be a strong requirement. Carbonaceous matter, on the other hand, appears to be rapidly recycled in the ISM and, in contrast to silicates, there are viable mechanisms for its re-formation in the ISM.

Iron mineralogy and bioaccessibility of dust generated from soils as determined by reflectance spectroscopy and magnetic and chemical properties--Nellis Dunes recreational area, Nevada

Science.gov (United States)

Goldstein, Harland L.; Reynolds, Richard L.; Morman, Suzette A.; Moskowitz, Bruce; Kokaly, Raymond F.; Goossens, Dirk; Buck, Brenda J.; Flagg, Cody; Till, Jessica; Yauk, Kimberly; Berquó, Thelma S.

2013-01-01

Atmospheric mineral dust exerts many important effects on the Earth system, such as atmospheric temperatures, marine productivity, and melting of snow and ice. Mineral dust also can have detrimental effects on human health through respiration of very small particles and the leaching of metals in various organs. These effects can be better understood through characterization of the physical and chemical properties of dust, including certain iron oxide minerals, for their extraordinary radiative properties and possible effects on lung inflammation. Studies of dust from the Nellis Dunes recreation area near Las Vegas, Nevada, focus on characteristics of radiative properties (capacity of dust to absorb solar radiation), iron oxide mineral type and size, chemistry, and bioaccessibility of metals in fluids that simulate human gastric, lung, and phagolysosomal fluids. In samples of dust from the Nellis Dunes recreation area with median grain sizes of 2.4, 3.1, and 4.3 micrometers, the ferric oxide minerals goethite and hematite, at least some of it nanosized, were identified. In one sample, in vitro bioaccessibility experiments revealed high bioaccessibility of arsenic in all three biofluids and higher leachate concentration and bioaccessibility for copper, uranium, and vanadium in the simulated lung fluid than in the phagolysosomal fluid. The combination of methods used here to characterize mineral dust at the Nellis Dunes recreation area can be applied to global dust and broad issues of public health.

Phthalates in dormitory and house dust of northern Chinese cities: Occurrence, human exposure, and risk assessment.

Science.gov (United States)

Li, Hai-Ling; Song, Wei-Wei; Zhang, Zi-Feng; Ma, Wan-Li; Gao, Chong-Jing; Li, Jia; Huo, Chun-Yan; Mohammed, Mohammed O A; Liu, Li-Yan; Kannan, Kurunthachalam; Li, Yi-Fan

2016-09-15

Phthalates are widely used chemicals in household products, which severely affect human health. However, there were limited studies emphasized on young adults' exposure to phthalates in dormitories. In this study, seven phthalates were extracted from indoor dust that collected in university dormitories in Harbin, Shenyang, and Baoding, in the north of China. Dust samples were also collected in houses in Harbin for comparison. The total concentrations of phthalates in dormitory dust in Harbin and Shenyang samples were significantly higher than those in Baoding samples. The total geometric mean concentration of phthalates in dormitory dust in Harbin was lower than in house dust. Di-(2-ethylhexyl) phthalate (DEHP) was the most abundant phthalate in both dormitory and house dust. The daily intakes of the total phthalates, carcinogenic risk (CR) of DEHP, hazard index (HI) of di-isobutyl phthalate (DiBP), dibutyl phthalate (DBP), and DEHP were estimated, the median values for all students in dormitories were lower than adults who live in the houses. Monte Carlo simulation was applied to predict the human exposure risk of phthalates. HI of DiBP, DBP, and DEHP was predicted according to the reference doses (RfD) provided by the United States Environmental Protection Agency (U.S.EPA) and the reference doses for anti-androgenicity (RfD AA) developed by Kortenkamp and Faust. The results indicated that the risks of some students had exceeded the limitation, however, the measured results were not exceeded the limitation. Risk quotients (RQ) of DEHP were predicted based on China specific No Significant Risk Level (NSRL) and Maximum Allowable Dose Level (MADL). The predicted results of CR and RQ of DEHP suggested that DEHP could pose a health risk through intake of indoor dust. Copyright © 2016 Elsevier B.V. All rights reserved.

DUST PRODUCTION AND MASS LOSS IN THE GALACTIC GLOBULAR CLUSTER NGC 362

International Nuclear Information System (INIS)

Boyer, Martha L.; Gordon, Karl D.; Meixner, Margaret; Sewilo, Marta; Shiao, Bernie; Whitney, Barbara; McDonald, Iain; Van Loon, Jacco Th.; Oliveira, Joana M.; Babler, Brian; Bracker, Steve; Meade, Marilyn; Block, Miwa; Engelbracht, Charles; Misselt, Karl; Hora, Joe; Indebetouw, Remy

2009-01-01

We investigate dust production and stellar mass loss in the Galactic globular cluster NGC 362. Due to its close proximity to the Small Magellanic Cloud (SMC), NGC 362 was imaged with the Infrared Array Camera and Multiband Imaging Photometer cameras onboard the Spitzer Space Telescope as part of the Surveying the Agents of Galaxy Evolution (SAGE-SMC) Spitzer Legacy program. We detect several cluster members near the tip of the red giant branch (RGB) that exhibit infrared excesses indicative of circumstellar dust and find that dust is not present in measurable quantities in stars below the tip of the RGB. We modeled the spectral energy distribution (SED) of the stars with the strongest IR excess and find a total cluster dust mass-loss rate of 3.0 +2.0 -1.2 x 10 -9 M sun yr -1 , corresponding to a gas mass-loss rate of 8.6 +5.6 -3.4 x 10 -6 M sun yr -1 , assuming [Fe/H] =-1.16. This mass loss is in addition to any dustless mass loss that is certainly occurring within the cluster. The two most extreme stars, variables V2 and V16, contribute up to 45% of the total cluster dust-traced mass loss. The SEDs of the more moderate stars indicate the presence of silicate dust, as expected for low-mass, low-metallicity stars. Surprisingly, the SED shapes of the stars with the strongest mass-loss rates appear to require the presence of amorphous carbon dust, possibly in combination with silicate dust, despite their oxygen-rich nature. These results corroborate our previous findings in ω Centauri.

Risk of Adverse Health and Performance Effects of Celestial Dust Exposure

Science.gov (United States)

Scully, Robert R.; Meyers, Valerie E.

2015-01-01

silica (Permissible Exposure Limit [PEL] 0.05 mg/m3) but more toxic than the nuisance dust titanium dioxide (TiO2 [PEL 5.0 mg/m3]). A PEL for episodic exposure to airborne lunar dust during a six-month stay on the lunar surface was established, in consultation with an independent, extramural panel of expert pulmonary toxicologists, at 0.3 mg/m3. The PEL provided for lunar dust is limited to the conditions and exposure specified therefore additional research remains to be accomplished with lunar dust to further address the issues of activation, address other areas of more unique lunar geology (Glotch et al., 2010; Greenhagen et al., 2010), examine potential toxicological effects of inhaled or ingested dust upon other organ systems, such cardiovascular, nervous systems, and examine effects of acute exposure to massive doses of dust such as may occur during off-nominal situations. Work to support the establishment of PELs for Martian dust and dusts of asteroids remains to be accomplished. The literature that describes health effects of exposure to toxic terrestrial dusts provides substantial basis for concern that prolonged exposure to respirable celestial dust could be detrimental to human health. Celestial bodies where a substantial portion of the dust is in the respirable range or where the dusts have large reactive surface areas or contain transition metals or volatile organics, represent greater risks of adverse effects from exposure to the dust. It is possible that in addition to adverse effects to the respiratory system, inhalation and ingestion of celestial dusts could pose risks to other systems

Dust extinction and X-ray emission from the starburst galaxy NGC 1482

Science.gov (United States)

Vagshette, N. D.; Pandge, M. B.; Pandey, S. K.; Patil, M. K.

2012-07-01

We present the results based on multiwavelength imaging observations of the prominent dust lane starburst galaxy NGC 1482 aimed to investigate the extinction properties of dust existing in the extreme environment. (B-V) colour-index map derived for the starburst galaxy NGC 1482 confirms two prominent dust lanes running along its optical major axis and are found to extend up to ˜11 kpc. In addition to the main lanes, several filamentary structures of dust originating from the central starburst are also evident. Though, the dust is surrounded by exotic environment, the average extinction curve derived for this target galaxy is compatible with the Galactic curve, with RV = 3.05, and imply that the dust grains responsible for the optical extinction in the target galaxy are not really different than the canonical grains in the Milky Way. Our estimate of total dust content of NGC 1482 assuming screening effect of dust is ˜2.7 × 105 M⊙, and provide lower limit due to the fact that our method is not sensitive to the intermix component of dust. Comparison of the observed dust in the galaxy with that supplied by the SNe to the ISM, imply that this supply is not sufficient to account for the observed dust and hence point towards the origin of dust in this galaxy through a merger like event. Our multiband imaging analysis reveals a qualitative physical correspondence between the morphologies of the dust and Hα emission lines as well as diffuse X-ray emission in this galaxy. Spatially resolved spectral analysis of the hot gas along outflows exhibit a gradient in the temperature. Similar gradient was also noticed in the measured values of metallicity, indicating that the gas in the halo is not yet enriched. High resolution, 2-8 keV Chandra image reveals a pair of point sources in the nuclear region with their luminosities equal to 2.27 × 1039 erg s-1 and 9.34 × 1039 erg s-1, and are in excess of the Eddington-limit of 1.5 M⊙ accreting source. Spectral analysis of these

Devoluming method and device for radioactive metal wastes containing zirconium alloy

International Nuclear Information System (INIS)

Komatsu, Masahiko; Wada, Ryutaro.

1996-01-01

The present invention concerns a method of sealing radioactive metal wastes in a capsule and compressing the capsule for devoluming treatment. The method comprises a step of carrying radioactive metal wastes into a sealed chamber having a capacity somewhat greater than that of the capsule, a deaerating step of sucking the air in the sealed chamber to attain a substantially vacuum state, a compression-devoluming step of compression-devoluming the capsule by reducing the volume of the sealed chamber and a transporting step of transporting the devolumed capsule from the sealed chamber. The sealed chamber to which the capsule incorporated with radioactive metal wastes containing a zirconium alloy is carried is then deaerated into a substantially vacuum state. Even if ignitable powdery dusts are generated from the radioactive metal wastes crushed by compression-devoluming of the capsule in the succeeding compression-devoluming step, since the air necessary for ignition is not present, ignition of the powdery dusts is prevented. Alternatively, since the inside of the sealed chamber is filled with an inert gas, ignition of the powdery dusts can effectively be prevented. (N.H.)

FY 2000 report on the results of the R and D of the immediately effective/innovative energy technology. Development of the regenerative technology of energy saving type metal dust; 2000 nendo sokkoteki kakushinteki energy gijutsu kenkyu kaihatsu seika hokokusho. Sho energy gata kinzoku dust kaisei gijutsu no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

The development was proceeded with of the technology to recover iron and zinc components directly from high temperature exhaust gas emitted from the steel-making use electric furnace, etc. This process is more simplified than the conventional dust treatment process and markedly reduces the energy needed for zinc recovery. In FY 2000, the following were carried out: 1) development of the element technology to recover metal components in high temperature exhaust gas; 2) development of the technology to optimize the recovery process for metal components in high temperature exhaust gas. In 1), the following were proceeded with: grasp of conditions for metal recovery; development of the equipment to select/separate low vapor-pressure metal components; development of the heavy metal separation equipment to select/condensate zinc. As to the development of the equipment to select/separate low vapor-pressure metal components, it was confirmed by the element test that it was possible to separate iron by carbon material filter. Further, the reaction amount of gasification of carbon material was estimated to be small by the element test and simulational calculation. In 2), the bench-scale test device and small pilot test device were designed/fabricated. (NEDO)

Is lead dust within nuclear medicine departments a hazard to pediatric patients?

Science.gov (United States)

Hulbert, Shannon M; Carlson, Katherine A

2009-09-01

Because of the penetrating ability of the radiation used in nuclear medicine, metallic lead is widely used as radiation shielding. However, this shielding may present an insidious health hazard because of the dust that is readily removed from the surfaces of lead objects. The lead dust may become airborne, contaminate floors and other nearby surfaces, and be inadvertently inhaled or ingested by patients. We determined if the quantity of lead dust encountered within nuclear medicine departments exceeded Environmental Protection Agency (EPA) standards. For lead dust quantification, professional lead test kits were used to sample fifteen 1-ft(2) sections of different surfaces within the department. Four samples were collected once per week from each site. The samples were then submitted to a National Lead Laboratory-accredited program for a total lead measurement. Lead contamination (mug/ft(2)) for each of the 60 samples was compared with the EPA standards for lead dust. Lead contamination was present at 6 of the 15 sites, and of 60 samples, 18 exceeded the EPA standard of 50 mug/ft(2). Lead contamination is present within nuclear medicine departments, and corrective measures should be considered when dealing with pediatric patients. A larger series needs to be conducted to confirm these findings.

Ways of far-distance dust transport onto Caucasian glaciers and chemical composition of snow on the Western plateau of Elbrus

Directory of Open Access Journals (Sweden)

S. S. Kutuzov

2014-01-01

Full Text Available We present and discuss the chronology of dust deposition events documented by the shallow firn and ice cores extracted on the Western Plateau, Mt. Elbrus (5150 m a.s.l. in 2009, 2012 and 2013. Snow and ice samples were analysed for major ions and minor element concentrations including heavy metals. Dust layers are formed on the surface of the glaciers as a result of atmospheric transport of mineral dust and aerosol particles to the Caucasus region. Satellite imagery (SEVIRI, trajectory models, and meteorological data were used for accurate dating of each the dust layers revealed in the ice cores. Then we tried to determine origins of the dust clouds and to investigate their transport pathways with high resolution (50–100 km. It was found that the desert dust is deposited on Caucasus glaciers 3–7 times in a year and it comes mainly from deserts of the Middle East and more rarely from the Northern Sahara desert. For the first time average annual dust flux (264 µg/cm2 per a year and average mass concentration (1.7 mg/kg over the period 2007–2013 were calculated for this region. The deposition of dust resulted in elevated concentrations consists of mostly ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from various sources in the Middle East, including Mesopotamia, or similar dust clouds passing over the Middle East are characterised by high concentrations of nitrates and ammonia that may be related to atmospheric transport of ammonium from agricultural lands that may explain high concentrations of ammonium in the dust originating from this region. Mean values of crustal enrichment factors (EF for the measured minor elements including heavy metals were calculated. We believe that high content of Cu, Zn and Cd can be a result of possible contribution from anthropogenic sources. Studies of the Caucasus ice cores may allow obtaining new independent data on the atmosphere circulation and high-altitude environment of this region.

THE OBSERVED RELATION BETWEEN STELLAR MASS, DUST EXTINCTION, AND STAR FORMATION RATE IN LOCAL GALAXIES

International Nuclear Information System (INIS)

Zahid, H. J.; Kewley, L. J.; Kudritzki, R. P.; Yates, R. M.

2013-01-01

In this study, we investigate the relation between stellar mass, dust extinction, and star formation rate (SFR) using ∼150,000 star-forming galaxies from SDSS DR7. We show that the relation between dust extinction and SFR changes with stellar mass. For galaxies at the same stellar mass, dust extinction is anti-correlated with the SFR at stellar masses 10 M ☉ . There is a sharp transition in the relation at a stellar mass of 10 10 M ☉ . At larger stellar masses, dust extinction is positively correlated with the SFR for galaxies at the same stellar mass. The observed relation between stellar mass, dust extinction, and SFR presented in this study helps to confirm similar trends observed in the relation between stellar mass, metallicity, and SFR. The relation reported in this study provides important new constraints on the physical processes governing the chemical evolution of galaxies. The correlation between SFR and dust extinction for galaxies with stellar masses >10 10 M ☉ is shown to extend to the population of quiescent galaxies suggesting that the physical processes responsible for the observed relation between stellar mass, dust extinction, and SFR may be related to the processes leading to the shutdown of star formation in galaxies.

THE OBSERVED RELATION BETWEEN STELLAR MASS, DUST EXTINCTION, AND STAR FORMATION RATE IN LOCAL GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Zahid, H. J.; Kewley, L. J.; Kudritzki, R. P. [Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Yates, R. M. [Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)

2013-02-15

In this study, we investigate the relation between stellar mass, dust extinction, and star formation rate (SFR) using {approx}150,000 star-forming galaxies from SDSS DR7. We show that the relation between dust extinction and SFR changes with stellar mass. For galaxies at the same stellar mass, dust extinction is anti-correlated with the SFR at stellar masses <10{sup 10} M {sub Sun }. There is a sharp transition in the relation at a stellar mass of 10{sup 10} M {sub Sun }. At larger stellar masses, dust extinction is positively correlated with the SFR for galaxies at the same stellar mass. The observed relation between stellar mass, dust extinction, and SFR presented in this study helps to confirm similar trends observed in the relation between stellar mass, metallicity, and SFR. The relation reported in this study provides important new constraints on the physical processes governing the chemical evolution of galaxies. The correlation between SFR and dust extinction for galaxies with stellar masses >10{sup 10} M {sub Sun} is shown to extend to the population of quiescent galaxies suggesting that the physical processes responsible for the observed relation between stellar mass, dust extinction, and SFR may be related to the processes leading to the shutdown of star formation in galaxies.

Exploring the Dust Content of Galactic Winds with Herschel. II. Nearby Dwarf Galaxies*

Science.gov (United States)

McCormick, Alexander; Veilleux, Sylvain; Meléndez, Marcio; Martin, Crystal L.; Bland-Hawthorn, Joss; Cecil, Gerald; Heitsch, Fabian; Müller, Thomas; Rupke, David S. N.; Engelbracht, Chad

2018-03-01

We present results from analysis of deep Herschel Space Observatory observations of six nearby dwarf galaxies known to host galactic-scale winds. The superior far-infrared sensitivity and angular resolution of Herschel have allowed detection of cold circumgalactic dust features beyond the stellar components of the host galaxies traced by Spitzer 4.5 μm images. Comparisons of these cold dust features with ancillary data reveal an imperfect spatial correlation with the ionized gas and warm dust wind components. We find that typically ˜10-20% of the total dust mass in these galaxies resides outside of their stellar disks, but this fraction reaches ˜60% in the case of NGC 1569. This galaxy also has the largest metallicity (O/H) deficit in our sample for its stellar mass. Overall, the small number of objects in our sample precludes drawing strong conclusions on the origin of the circumgalactic dust. We detect no statistically significant trends with star formation properties of the host galaxies, as might be expected if the dust were lifted above the disk by energy inputs from on-going star formation activity. Although a case for dust entrained in a galactic wind is seen in NGC 1569, in all cases, we cannot rule out the possibility that some of the circumgalactic dust might be associated instead with gas accreted or removed from the disk by recent galaxy interaction events, or that it is part of the outer gas-rich portion of the disk that lies below the sensitivity limit of the Spitzer 4.5 μm data.

Essays on household time allocation decisions in a collective household model

OpenAIRE

Silvennoinen, Heidi

2008-01-01

This thesis considers the consequences of traditional division of labour in households in a setting where spouses are allowed to have distinct preferences. This approach leads to different results compared to the traditional unitary approach and is better equipped to take into consideration gender related issues of household decision making. The thesis consists of three theoretical essays where the household production theory is applied in the collective household model. The first essay ...

DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

Energy Technology Data Exchange (ETDEWEB)

Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J., E-mail: hhwang@cfa.harvard.edu, E-mail: sandrews@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-11-01

We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S{sub ν}(880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S{sub ν}(880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10{sup 11}(L{sub ☉}) and 4-14 × 10{sup 7}(M{sub ☉}), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution.

Influence of Addition of Briquettes with Dust Content into the Charge of Electric Induction Furnace on Cast Iron Quality

Directory of Open Access Journals (Sweden)

Pribulová A.

2012-09-01

Full Text Available Foundry dust from blasting and grinding of castings contain a high amount of iron, ergo it is possible its recycling in foundry process. Dust was compacted by briquetting, two kinds of briquettes were prepared (A contained 95% magnetic part of dust from casting blasting +5% bentonite and B contained 95% mixture of dust from casting grinding and magnetic part of dust from casting blasting + 5% bentonite and used as a part of charge into the electric induction furnace. It was found that addition of briquettes has had an influence of a chemical composition of cast iron above all on content of sulphur, phosphorus and silicon. It was not reflected in decrease in tensile strength and in microstructure. Yield of metal from briquettes was not lower then 70%.

Influence of Addition of Briquettes with Dust Content into the Charge of Electric Induction Furnace on Cast Iron Quality

Directory of Open Access Journals (Sweden)

A. Pribulová

2012-09-01

Full Text Available Foundry dust from blasting and grinding of castings contain a high amount of iron, ergo it is possible its recycling in foundry process.Dust was compacted by briquetting, two kinds of briquettes were prepared (A contained 95% magnetic part of dust from casting blasting+5% bentonite and B contained 95% mixture of dust from casting grinding and magnetic part of dust from casting blasting + 5%bentonite and used as a part of charge into the electric induction furnace. It was found that addition of briquettes has had an influence of a chemical composition of cast iron above all on content of sulphur, phosphorus and silicon. It was not reflected in decrease in tensile strength and in microstructure. Yield of metal from briquettes was not lower then 70%.

Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation

International Nuclear Information System (INIS)

Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.

2002-01-01

A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential

Basis for criteria for exemption of decommissioning waste: reprocessing of dust from recycling of steel

International Nuclear Information System (INIS)

Elert, M.; Wiborgh, M.

1992-06-01

This study is a part of a larger study with the purpose to provide the authority concerned, the Swedish Radiation Protection Institute (SSI), with technical background material needed for future decisions concerning exemption levels for recycling and disposal of material originating from decommissioned nuclear power reactors. The dismantling of nuclear power reactors will give rise to large amounts of steel scrap with a very low activity concentration. It is of interest to exempt this material from regulatory control in order to make recycling possible. During the melting of steel scrap dust will be formed which is collected in the off-gas cleaning system of the furnace. Radionuclides may be enriched in this dust, and thereby obtain a higher activity concentration than the melted scrap. Presently, there is a strong interest to reprocess these dusts with the objectives to recover valuable metals and to reduce the amounts of waste harmful to the environment. During the reprocessing of dusts collected from the melting process a further redistribution and reconcentration of radionuclides may occur. In this report the treatment of dust from steel melting is described, the potential reconcentration of radionuclides is analyzed, and the potential radiological consequences are estimated. The study has focussed on the reprocessing of dust with the plasma method used at ScanDust in Sweden, and with the Waelz process used in, for example Spain and Germany. Various factors as economical, political and future developments of dust treatment and steel processes will determine the amounts of dusts produced and also to what degree dust will be reprocessed in the future. (au)

Metals Exposures of Residents Living Near the Akaki River in Addis Ababa, Ethiopia: A Cross-Sectional Study

Directory of Open Access Journals (Sweden)

Ellen Yard

2015-01-01

Full Text Available Background. The Akaki River in Ethiopia has been found to contain elevated levels of several metals. Our objectives were to characterize metals exposures of residents living near the Akaki River and to assess metal levels in their drinking water. Methods. In 2011, we conducted a cross-sectional study of 101 households in Akaki-Kality subcity (near the Akaki River and 50 households in Yeka subcity (distant to the Akaki River. One willing adult in each household provided urine, blood, and drinking water sample. Results. Urinary molybdenum (p<0.001, tungsten (p<0.001, lead (p<0.001, uranium (p<0.001, and mercury (p=0.049 were higher in Akaki-Kality participants compared to Yeka participants. Participants in both subcities had low urinary iodine; 45% met the World Health Organization (WHO classification for being at risk of moderate iodine deficiency. In Yeka, 47% of households exceeded the WHO aesthetic-based reference value for manganese; in Akaki-Kality, only 2% of households exceeded this value (p<0.001. There was no correlation between metals levels in water samples and clinical specimens. Conclusions. Most of the exposures found during this investigation seem unlikely to cause acute health effects based on known toxic thresholds. However, toxicity data for many of these metals are very limited.

Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation

International Nuclear Information System (INIS)

Wei Nanxia; Xue Jukui

2006-01-01

Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave

National Alcohol Survey of households in Trinidad and Tobago (NASHTT: Alcohol use in households

Directory of Open Access Journals (Sweden)

R.G. Maharaj

2017-04-01

Full Text Available Abstract Background To determine the patterns of alcohol use among households in Trinidad and Tobago (T&T and to estimate the association between alcohol use and negative psychological, social, or physical events experienced by the household. Methods A convenience sample of 1837 households across T&T. We identified bivariate correlates of alcohol use, and heavy episodic drinking using chi-square and t-test analyses and used multivariable logistic regression to estimate adjusted associations between household alcohol use and experiences within the past 12 months adjusted for sociodemographic covariates. Results One thousand five hundred two households had complete data for all variables (82% response rate. Nearly two thirds (64% of households included alcohol users; 57% of household that consumed alcohol also reported heavy episodic drinking. Households that reported alcohol consumption were significantly more likely to report illnesses within the households, relationship problems, and behavioral and antisocial problems with children. Among households where a member was employed, those who consumed alcohol were nearly twice as likely (OR = 1.98; 95% confidence interval (CI 1.03, 3.82 to have a household member call in sick to work and 2.9 times as likely (OR = 2.9; CI 1.19, 7.04 to have a household member suffer work related problems compared with households who reported not consuming alcohol. Conclusions Approximately two thirds of households in T&T reported using alcohol. These households were more likely to report psychological, physical, and social problems. These findings would support efforts to enforce current policies, laws, and regulations as well as new strategies to reduce the impact of harmful alcohol consumption on households in T&T.

Briquetting of EAF Dust for its Utilisation in Metallurgical Processes

Directory of Open Access Journals (Sweden)

Magdziarz Aneta

2015-06-01

Full Text Available Dust generated at an electric arc furnace during steel production industry is still not a solved problem. Electric arc furnace dust (EAF is a hazardous solid waste. Sintering of well-prepared briquetted mixtures in a shaft furnace is one of possible methods of EAFD utilisation. Simultaneously some metal oxides from exhaust gases can be separated. In this way, various metals are obtained, particularly zinc is recovered. As a result, zinc-free briquettes are received with high iron content which can be used in the steelmaking process. The purpose of the research was selecting the appropriate chemical composition of briquettes of the required strength and coke content necessary for the reduction of zinc oxide in a shaft furnace. Based on the results of the research the composition of the briquettes was selected. The best binder hydrated lime and sugar molasses and the range of proper moisture of mixture to receive briquettes of high mechanical strength were also chosen and tested. Additionally, in order to determine the thermal stability for the selected mixtures for briquetting thermal analysis was performed. A technological line of briquetting was developed to apply in a steelworks.

The Lunar Dust Environment

Science.gov (United States)

Szalay, Jamey Robert

Planetary bodies throughout the solar system are continually bombarded by dust particles, largely originating from cometary activities and asteroidal collisions. Surfaces of bodies with thick atmospheres, such as Venus, Earth, Mars and Titan are mostly protected from incoming dust impacts as these particles ablate in their atmospheres as 'shooting stars'. However, the majority of bodies in the solar system have no appreciable atmosphere and their surfaces are directly exposed to the flux of high speed dust grains. Impacts onto solid surfaces in space generate charged and neutral gas clouds, as well as solid secondary ejecta dust particles. Gravitationally bound ejecta clouds forming dust exospheres were recognized by in situ dust instruments around the icy moons of Jupiter and Saturn, and had not yet been observed near bodies with refractory regolith surfaces before NASA's Lunar Dust and Environment Explorer (LADEE) mission. In this thesis, we first present the measurements taken by the Lunar Dust Explorer (LDEX), aboard LADEE, which discovered a permanently present, asymmetric dust cloud surrounding the Moon. The global characteristics of the lunar dust cloud are discussed as a function of a variety of variables such as altitude, solar longitude, local time, and lunar phase. These results are compared with models for lunar dust cloud generation. Second, we present an analysis of the groupings of impacts measured by LDEX, which represent detections of dense ejecta plumes above the lunar surface. These measurements are put in the context of understanding the response of the lunar surface to meteoroid bombardment and how to use other airless bodies in the solar system as detectors for their local meteoroid environment. Third, we present the first in-situ dust measurements taken over the lunar sunrise terminator. Having found no excess of small grains in this region, we discuss its implications for the putative population of electrostatically lofted dust.

Determination of heavy metals in the fruit of date palm growing at different locations of Riyadh

OpenAIRE

Aldjain, Ibrahim M.; Al-Whaibi, Mohamed H.; Al-Showiman, Salim S.; Siddiqui, Manzer H.

2011-01-01

Exposure of heavy metals to human beings has risen dramatically in the last 50 years. In today’s urban and industrial society, there is no escaping from exposure to toxic chemicals and heavy metals. Humans are more likely to be exposed to heavy metal contamination from the dust that adheres to edible plants than from bioaccumulation. This is because it is very difficult to wash off all the dust particles from the plant material before ingesting them. The objectives of this experiment were to ...

Farm Households Food Production and Households' Food Security ...

African Journals Online (AJOL)

Food is an important basic human need for survival, growth, and good health. Most rural households in Tanzania, Kahama district inclusive produce the food they consume. Despite this reality, a number of households in the district suffer from food insecurity. However, there are inequalities across the districtfs ecological ...

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

Science.gov (United States)

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

2012-01-01

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

Fractal dust grains in plasma

International Nuclear Information System (INIS)

Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

2012-01-01

Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

Selective leaching process for the recovery of copper and zinc oxide from copper-containing dust.

Science.gov (United States)

Wu, Jun-Yi; Chang, Fang-Chih; Wang, H Paul; Tsai, Ming-Jer; Ko, Chun-Han; Chen, Chih-Cheng

2015-01-01

The purpose of this study was to develop a resource recovery procedure for recovering copper and zinc from dust produced by copper smelting furnaces during the manufacturing of copper-alloy wires. The concentrations of copper in copper-containing dust do not meet the regulation standards defined by the Taiwan Environmental Protection Administration; therefore, such waste is classified as hazardous. In this study, the percentages of zinc and copper in the dust samples were approximately 38.4% and 2.6%, respectively. To reduce environmental damage and recover metal resources for industrial reuse, acid leaching was used to recover metals from these inorganic wastes. In the first stage, 2 N of sulphuric acid was used to leach the dust, with pH values controlled at 2.0-3.0, and a solid-to-liquid ratio of 1:10. The results indicated that zinc extraction efficiency was higher than 95%. A selective acid leaching process was then used to recover the copper content of the residue after filtration. In the second stage, an additional 1 N of sulphuric acid was added to the suspension in the selective leaching process, and the pH value was controlled at 1.5-2.0. The reagent sodium hydroxide (2 N) was used as leachate at a pH greater than 7. A zinc hydroxide compound formed during the process and was recovered after drying. The yields for zinc and copper were 86.9-93.5% and 97.0-98.9%, respectively.