Science.gov

Sample records for dust lead loadings

  1. Lead loadings in household dust in Delhi, India.

    PubMed

    Kumar, A; Scott Clark, C

    2009-10-01

    Lead in household dust is dangerous to children who ingest lead from playing close to the ground, and having frequent hand-to-mouth contact. Although there have been several investigations of lead levels in India in air, blood and new paint, the literature is sparse on the levels of lead in household dust. This study analyzed 99 samples of dust taken from bare floors and 49 samples of dust taken from windowsills in a cross-section of Delhi, India houses for lead loadings. The arithmetic mean of lead loading for floor samples and windowsill dust samples was found to be 36.24 microg/ft(2) and 129.5 microg/ft(2), respectively. The geometric mean of dust lead loading for floor and interior windowsill samples was found to be 19.7 microg/ft(2) and 75.5 microg/ft(2), respectively. Comparing the results with US geometric mean dust lead levels from a national cross-section of US housing, which in 2000 were 1.1 microg/ft(2) and 9.4 microg/ft(2) on floors and windowsills, respectively as reported by Jacobs et al. (2002) suggests that the lead content of the dust in Delhi homes is much higher than that in the national data in the US and that the levels pose a hazard to children. Practical Implications The present study is first of its kind in this part of the world. In the context of ongoing efforts to eliminate lead from paints worldwide this research will help the scientists and policy makers in assessing the Children's exposure to lead in developing country as well. Since more than one half of the housing units tested had at least one dust lead sample exceeding US health-based standards, health care providers and public health officials need to give attention to possible lead poisoning in Delhi children. Routine blood lead screening of children should follow recommended public health practice for children at risk. Additional larger-scale studies are needed in Delhi and elsewhere to determine how representative these findings are and to attempt to delineate the sources of

  2. Residential dust lead loading immediately after intervention in the HUD lead hazard control grant program.

    PubMed

    Dixon, Sherry L; Wilson, Jonathan W; Succop, Paul A; Chen, Mei; Galke, Warren A; Menrath, William; Clark, C Scott

    2004-11-01

    At the conclusion of most lead hazard control interventions in federally assisted housing built before 1978, a certified clearance examiner must verify that the lead hazard control work was completed as specified and that the area is safe for residents, a process referred to as clearance. This study explores the experience of 14 grantees participating in the Evaluation of the HUD Lead-Based Paint Hazard Control Grant Program in passing clearance. The study also considers how preintervention lead levels (interior dust and paint), building condition/characteristics, and the scope of work influenced initial clearance dust lead loadings and clearance rates. At the initial clearance inspection, 80% of the 2682 dwellings achieved grantee-specific clearance standards on windowsills, window troughs (500 microg/ft2 and 800 microg/ft2, respectively), and floors (80, 100, or 200 microg/ft2 depending on state/local regulations at the dates of clearance in the mid-1990s), with individual grantee success rates ranging from 63 to 100%. Dwellings that failed initial clearance required an average of 1.13 retests to clear. The high level of success at clearance demonstrates that following methods for work site containment, lead hazard control, and cleaning similar to those recommended in the HUD Guidelines for the Evaluation and Control of Lead-Based Paint in Housing is effective. The most common lead hazard control intervention was window abatement accompanied by the repair or abatement of all other deteriorated lead-based paint (56% of dwellings). An additional 5% of dwellings were fully abated, 29% had lower intensity interventions. Interventions including window replacement are recommended to reduce dust lead loading on windowsills and troughs at clearance, but lower level interventions such as full paint stabilization are just as good at reducing floor dust lead loadings. Whatever lead hazard control activities are selected, the condition of the surfaces of interest should be

  3. A survey of spatially distributed exterior dust lead loadings in New York City

    SciTech Connect

    Caravanos, Jack; Weiss, Arlene L.; Blaise, Marc J.; Jaeger, Rudolph J. . E-mail: jaegerr@envmed.com

    2006-02-15

    This work documents ambient lead dust deposition values (lead loading) for the boroughs of New York City in 2003-2004. Currently, no regulatory standards exist for exterior concentrations of lead in settled dust. This is in contrast to the clearance and risk assessment standards that exist for interior residential dust. The reported potential for neurobehavioral toxicity and adverse cognitive development in children due to lead exposure prompts public health concerns about undocumented lead sources. Such sources may include settled dust of outdoor origin. Dust sampling throughout the five boroughs of NYC was done from the top horizontal portion of pedestrian traffic control signals (PTCS) at selected street intersections along main thoroughfares. The data (n=214 samples) show that lead in dust varies within each borough with Brooklyn having the highest median concentration (730{mu}g/ft{sup 2}), followed in descending order by Staten Island (452{mu}g/ft{sup 2}), the Bronx (382{mu}g/ft{sup 2}), Queens (198{mu}g/ft{sup 2}) and finally, Manhattan (175{mu}g/ft{sup 2}). When compared to the HUD/EPA indoor lead in dust standard of 40{mu}g/ft{sup 2}, our data show that this value is exceeded in 86% of the samples taken. An effort was made to determine the source of the lead in the dust atop of the PTCS. The lead in the dust and the yellow signage paint (which contains lead) were compared using isotopic ratio analysis. Results showed that the lead-based paint chip samples from intact signage did not isotopically match the dust wipe samples taken from the same surface. We know that exterior dust containing lead contributes to interior dust lead loading. Therefore, settled leaded dust in the outdoor environment poses a risk for lead exposure to children living in urban areas, namely, areas with elevated childhood blood lead levels and background lead dust levels from a variety of unidentified sources.

  4. Exterior surface dust lead, interior house dust lead and childhood lead exposure in an urban environment

    SciTech Connect

    Bornschein, R.L.; Succop, P.A.; Krafft, K.M.; Clark, C.S.; Peace, B.; Hammond, P.B.

    1986-01-01

    The impact of urban lead exposure is being examined in a prospective study of several hundred children followed from birth to five years of age. A wide range of social, behavioral, biological and environmental factors are being assessed at approximately one year intervals beginning at birth. Previous analyses on this cohort have indicated a strong relationship between hand lead and hand-to-mouth activity and suggests that this is an important mechanism of inadvertent ingestion of lead in infants and young children. The present analyses was undertaken to examine the joint influence of lead in exterior surface dust and interior lead-containing painted surfaces on lead levels in house dust. In addition the joint influence of exterior and interior surface dust lead on children's hand lead content and blood lead concentration was examined. At 18 months of age 38% of the observed variation in blood lead was accounted for by hand lead and dust lead. Interior paint lead and exterior surface dust lead accounted for 52% of the observed variation in interior surface dust lead concentration. Exterior surface dust lead, obtained from exterior surface scrapings, indirectly influenced blood lead through its impact on interior house dust lead and children's hand lead content, but had no observable direct impact on blood lead. 13 references, 4 figures, 3 tables.

  5. The influence of soil remediation on lead in house dust.

    PubMed

    von Lindern, Ian H; Spalinger, Susan M; Bero, Bridget N; Petrosyan, Varduhi; von Braun, Margrit C

    2003-02-15

    Lead in house dust has long been recognized as a principal source of excess lead absorption among children at the Bunker Hill Superfund Site (BHSS) in northern Idaho. House dust lead concentration from homeowner's vacuum cleaner bags has been monitored since the epidemic of childhood lead poisoning in 1974. Geometric mean house dust lead concentrations decreased from >10000 mg/kg in 1974 to approximately 4000 mg/kg in 1975, in response to air pollution control initiatives at the defective primary lead smelter. After smelter closure, 1983 mean dust lead concentrations were near 3000 mg/kg and were most dependent on soil sources. Following emergency soil removals from public areas and roadsides and fugitive dust control efforts in the mid-1980s, house dust lead decreased by approximately 40-60% to 1200-1500 mg/kg. In 1992, a cleanup goal of 500 mg/kg dust lead community average, with no individual home exceeding 1000 mg/kg, was adopted. This goal was to be achieved by a combination of contaminated soil removals and fugitive dust control efforts throughout the 21 square mile BHSS. Continual reductions in house dust lead concentrations have been noted throughout the residential area soil cleanup. Geometric mean house dust lead concentrations averaged approximately 500-600 mg/kg from 1996 to 1999 and dropped below 500 mg/kg in 2000. Analysis of these data indicates that approximately 20% of the variance in dust lead concentrations is attributed to yard, neighborhood, and community soil lead concentrations. Since 1996, dust lead concentrations and dust and lead loading rates have also been measured by dust mats placed at entryways into the homes. Neighborhood soil lead concentrations, household hygiene, the number of adults living in the home, and the number of hours a child spends outdoors in summer explain approximately 26% of the variance in mat dust lead loading rates. It is estimated that post-remedial house dust lead concentrations will stabilize at 400-500 mg

  6. Chemical speciation of lead dust associated with primary lead smelting.

    PubMed Central

    Spear, T M; Svee, W; Vincent, J H; Stanisich, N

    1998-01-01

    The research presented in this article assessed geochemical factors relating to dust produced during primary lead smelting. Bulk dust samples and size-selective airborne dust samples were collected from four areas of a primary lead smelter and analyzed by X-ray diffraction and sequential chemical extraction. X-ray diffraction showed that the smelter dusts were composed primarily of sulfides, oxides, sulfates, and silicates of metal ores, with galena being the primary dust component. Sequential extraction revealed the solubility of lead compounds at less than 7% in the exchangeable and mildly acidic steps for the bulk dusts collected from four smelter areas. The later steps of the extraction procedure were more effective in dissolving the lead compounds associated with the bulk dust samples, with 43%, 26%, and 8% of the total lead, in the ore storage, sinter, and blast/dross smelter areas, respectively, being extracted in the residual step. Sequential extraction of coarse airborne dust samples from the ore storage and sinter plant showed that 1.2% and 4.1% of the total lead, respectively, was exchangeable. The finer particle size fractions from these areas of the smelter showed higher percentages of exchangeable lead. Of the course airborne dust from the blast/dross furnace processes, 65% of the total lead was exchangeable. However, the largest percentage of lead from these areas was associated with the finer particle-size fractions. If lead bioavailability is related to its solubility as determined through sequential extraction, the health hazards associated with lead exposure may be appreciably enhanced in the blast and dross furnace processes. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:9721256

  7. Amplification of dust loading in Martian dust devils by self-shadowing

    NASA Astrophysics Data System (ADS)

    Kuepper, M.; Wurm, G.

    2016-08-01

    Insolation of the Martian soil leads to a sub-surface overpressure due to thermal creep gas flow. This could support particle entrainment into the atmosphere. Short time shadowing e.g. by the traverse of a larger dust devil would enhance this effect. We find in microgravity experiments that mass ejection rates are increased by a factor of 10 for several seconds if a light source of 12.6 kW/m2 is turned off. Scaled to Mars this implies that self-shadowing of a partially opaque dust devil might lead to a strongly amplified flux of lifted material. We therefore suggest that self-shadowing might be a mechanism on Mars to increase the total dust loading of a dust devil and keep it self-sustained.

  8. Interaction of adhered metallic dust with transient plasma heat loads

    NASA Astrophysics Data System (ADS)

    Ratynskaia, S.; Tolias, P.; Bykov, I.; Rudakov, D.; De Angeli, M.; Vignitchouk, L.; Ripamonti, D.; Riva, G.; Bardin, S.; van der Meiden, H.; Vernimmen, J.; Bystrov, K.; De Temmerman, G.

    2016-06-01

    The first study of the interaction of metallic dust (tungsten, aluminum) adhered on tungsten substrates with transient plasma heat loads is presented. Experiments were carried out in the Pilot-PSI linear device with transient heat fluxes up to 550 MW m‑2 and in the DIII-D divertor tokamak. The central role of the dust-substrate contact area in heat conduction is highlighted and confirmed by heat transfer simulations. The experiments provide evidence of the occurrence of wetting-induced coagulation, a novel growth mechanism where cluster melting accompanied by droplet wetting leads to the formation of larger grains. The physical processes behind this mechanism are elucidated. The remobilization activity of the newly formed dust and the survivability of tungsten dust on hot surfaces are documented and discussed in the light of implications for ITER.

  9. Northern Idaho house dust and soil lead levels compared to the Bunker Hill Superfund Site.

    PubMed

    Spalinger, Susan M; von Braun, Margrit C; Petrosyan, Varduhi; von Lindern, Ian H

    2007-07-01

    House dust has been identified as a major exposure medium for lead (Pb) in children. High levels of Pb in soil and house dust have been recorded at the Bunker Hill Superfund Site (BHSS) in northern Idaho, an historic mining and smelting district. Soil and dust remediation at the site was required; however, regional background soil and dust Pb levels had not been well characterized. The objective of this survey was to determine background house dust Pb levels and to compare those levels with concentrations, and dust and Pb loading rates measured at the BHSS. Soil and house dust samples were collected in five towns demographically similar to the BHSS but unaffected by the mining industry. The background concentrations and loading rates were significantly lower than those observed at the site. House age was a significant factor affecting background soil and house dust Pb concentrations and loading rates. PMID:17171279

  10. Solar wind mass-loading due to dust

    NASA Astrophysics Data System (ADS)

    Rasca, A. P.; Horányi, M.

    2013-06-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions by larger bodies in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We look at results obtained using a simple 1D hydrodynamic model to mass-load ionized dust into the the wind near the sonic point, which are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  11. Solar Wind Mass-Loading Due to Dust

    NASA Astrophysics Data System (ADS)

    Rasca, A.; Horanyi, M.

    2011-12-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We implement a hydrodynamic numerical model to generate a steady wind extending out to the inner heliosphere. Dust is introduced through a set of mass-loading source terms, and the model is evolved using a shock-capturing scheme. These results are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  12. ALPHA ATTENUATION DUE TO DUST LOADING

    SciTech Connect

    Dailey, A; Dennis Hadlock, D

    2007-08-09

    Previous studies had been done in order to show the attenuation of alpha particles in filter media. These studies provided an accurate correction for this attenuation, but there had not yet been a study with sufficient results to properly correct for attenuation due to dust loading on the filters. At the Savannah River Site, filter samples are corrected for attenuation due to dust loading at 20%. Depending on the facility the filter comes from and the duration of the sampling period, the proper correction factor may vary. The objective of this study was to determine self-absorption curves for each of three counting instruments. Prior work indicated significant decreases in alpha count rate (as much as 38%) due to dust loading, especially on filters from facilities where sampling takes place over long intervals. The alpha count rate decreased because of a decrease in the energy of the alpha. The study performed resulted in a set of alpha absorption curves for each of three detectors. This study also took into account the affects of the geometry differences in the different counting equipment used.

  13. Assessment of cleaning to control lead dust in homes of children with moderate lead poisoning: treatment of lead-exposed children trial.

    PubMed Central

    Ettinger, Adrienne S; Bornschein, Robert L; Farfel, Mark; Campbell, Carla; Ragan, N Beth; Rhoads, George G; Brophy, Merrill; Wilkens, Sherry; Dockery, Douglas W

    2002-01-01

    In this article we describe the assessment and control of lead dust exposure in the Treatment of Lead-exposed Children (TLC) Trial, a clinical trial of the effects of oral chelation on developmental end points in urban children with moderately elevated blood lead levels. To reduce potential lead exposure from settled dust or deteriorated paint during the drug treatment phase of the trial, the homes of 765 (98%) of the randomized children (both active and placebo drug treatment groups) were professionally cleaned. Lead dust measurements were made in a sample of 213 homes before and after cleaning. Geometric mean dust lead loadings before cleaning were 43, 29, 308, and 707 micro g/ft2 in the kitchen floor, playroom floor, playroom windowsill, and playroom window well samples respectively. Following cleaning, floor dust lead loadings were reduced on average 32% for paired floor samples (p < 0.0001), 66% for windowsills (p < 0.0001), and 93% for window wells (p < 0.0001). Cleaning was most effective for 146 homes with precleaning dust lead levels above the recommended clearance levels, with average reductions of 44%, 74%, and 93% for floors (p < 0.0001), windowsills (p < 0.0001), and window wells (p < 0.0001), respectively. Despite these substantial reductions in dust lead loadings, a single professional cleaning did not reduce the lead loadings of all dust samples to levels below current federal standards for lead in residential dust. Attainment of dust levels below current standards will require more intensive cleaning and lead hazard reduction strategies. PMID:12460817

  14. The contribution of lead-contaminated house dust and residential soil to children`s blood lead levels

    SciTech Connect

    Lanphear, B.P.; Matte, T.D.; Rogers, J.

    1998-10-01

    In 1992, the US Congress passed the Residential Lead-Based Paint Hazard Reduction Act, which requires the promulgation of health-based dust lead and soil lead standards for residential dwellings to prevent undue lead exposure in children. Unfortunately, the levels of lead in house dust and soil that are associated with elevated blood lead levels among US children remain poorly defined. This pooled analysis was done to estimate the contributions of lead-contaminated house dust and soil to children`s blood lead levels. The results of this pooled analysis, the most comprehensive existing epidemiologic analysis of childhood lead exposure, confirm that lead-contaminated house dust is the major source of lead exposure for children. These analyses further demonstrate that a strong relationship between interior dust lead loading and children`s blood lead levels persists at dust lead levels considerably below the US Department of Housing and urban Development`s current post-abatement standards and the Environmental Protection Agency`s guidance levels. Finally, these analyses demonstrate that a child`s age, race, mouthing behaviors, and study-site specific factors influence the predicted blood lead level at a given level of exposure. These data can be used to estimate the potential health impact of alternative health-based lead standards for residential sources of lead exposure.

  15. DEVELOPING AND IMPLEMENTING A LEAD DUST MONITORING, OUTREACH AND EDUCATION PROGRAM IN YOUR COMMUNITY/SYRACUSE LEAD DUST PROJECT

    EPA Science Inventory

    EPA has developed a technology transfer document (case-study) for the EMPACT Syracuse Lead Dust Project. The Lead Dust Project is designed to measure the lead dust content in homes and public buildings within the City of Syracuse, NY. The project also contains an educational comp...

  16. Lead in Chinese villager house dust

    NASA Astrophysics Data System (ADS)

    Bi, Xiangyang; Liu, Jinling; Han, Zhixuan

    2016-04-01

    House dust has been recognized as an important contributor to children's blood Pb. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with geometric mean and median concentration of 54 mg/kg and 42 mg/kg, respectively. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). The influences of outdoor soil Pb concentrations, dates of construction, house decorative materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decorative materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. The results of scanning electron microscopy (SEM) showed that Pb bearing particles appeared as cylindrical, flaky and irregular aggregates with the particle size ranging from about 10 to 800 μm. The energy dispersive X-ray microanalysis (EDX) suggested that Pb in the dust particles may be associated with calcium compounds. But the major fraction of Pb in the household dust samples was found to be strongly bound to Fe-Mn oxide phases (37%) while Pb present in minor fractions individually making up between 14 and 18% was characterized in falling order as residual, carbonate, organic/sulphide and exchangeable fractions by the sequential extraction method applied. Bioaccessible Pb making up an average proportion of 53% in the household dusts was significantly correlated to the Fe-Mn oxide phases of Pb.

  17. 42 CFR 84.1152 - Silica dust loading test; respirators designed as protection against dusts, fumes, and mists...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having an air contamination level less than 0.05 milligram per... Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having...

  18. 42 CFR 84.1152 - Silica dust loading test; respirators designed as protection against dusts, fumes, and mists...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having an air contamination level less than 0.05 milligram per... Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having...

  19. Volcanic loading: The dust veil index

    SciTech Connect

    Lamb, H.H.

    1985-09-01

    Dust ejected into the high atmosphere during explosive volcanic eruptions has been considered as a possible cause for climatic change. Dust veils created by volcanic eruptions can reduce the amount of light reaching the Earth`s surface and can cause reductions in surface temperatures. These climatic effects can be seen for several years following some eruptions and the magnitude and duration of the effects depend largely on the density or amount of tephra (i.e. dust) ejected, the latitude of injection, and atmospheric circulation patterns. Lamb (1970) formulated the Dust Veil Index (DVI) in an attempt to quantify the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact of a particular volcanic eruptions release of dust and aerosols over the years following the event. The DVI for any volcanic eruptions are available and have been used in estimating Lamb`s dust veil indices.

  20. Lead loading of urban streets by motor vehicle wheel weights.

    PubMed Central

    Root, R A

    2000-01-01

    This study documents that lead weights, which are used to balance motor vehicle wheels, are lost and deposited in urban streets, that they accumulate along the outer curb, and that they are rapidly abraded and ground into tiny pieces by vehicle traffic. The lead is so soft that half the lead deposited in the street is no longer visible after little more than 1 week. This lead loading of urban streets by motor vehicle wheel weights is continuous, significant, and widespread, and is potentially a major source of human lead exposure because the lead is concentrated along the outer curb where pedestrians are likely to step. Lead deposition at one intersection in Albuquerque, New Mexico, ranged from 50 to 70 kg/km/year (almost 11 g/ft(2)/year along the outer curb), a mass loading rate that, if accumulated for a year, would exceed federal lead hazard guidelines more than 10,000 times. Lead loading of major Albuquerque thoroughfares is estimated to be 3,730 kg/year. Wheel weight lead may be dispersed as fugitive dust, flushed periodically by storm water into nearby waterways and aquatic ecosystems, or may adhere to the shoes of pedestrians or the feet of pets, where it can be tracked into the home. I propose that lead from wheel weights contributes to the lead burden of urban populations. PMID:11049812

  1. Determination of road dust loadings and chemical characteristics using resuspension.

    PubMed

    Chen, Jianhua; Wang, Wei; Liu, Hongjie; Ren, Lihong

    2012-03-01

    The contribution of fugitive dust from traffic to air pollution can no longer be ignored in China. In order to obtain the road dust loadings and to understand the chemical characteristics of PM(10) and PM(2.5) from typical road dust, different paved roads in eight districts of Beijing were selected for dust collection during the four seasons of 2005. Ninety-eight samples from 28 roads were obtained. The samples were resuspended using equipment assembled to simulate the rising process of road dust caused by the wind or wheels in order to obtain the PM(10) and PM(2.5) filter samples. The average road dust loading was 3.82 g m(-2), with the highest of 24.22 g m(-2) being in Hutongs in the rural-urban continuum during winter. The road dust loadings on higher-grade roads were lower than those on lower-grade roads. Attention should be paid to the pollution in the rural-urban continuum areas. The sums of element abundances measured were 16.17% and 18.50% for PM(10) and PM(2.5) in road dust. The average abundances of OC and EC in PM(10) and PM(2.5) in road dust were 11.52%, 2.01% and 12.50%, 2.06%, respectively. The abundance of elements, water-soluble ions, and OC, EC in PM(10) and PM(2.5) resuspended from road dust did not change greatly with seasons and road types. The soil dust, construction dust, dust emitted from burning coal, vehicle exhaust, and deposition of particles in the air were the main sources of road dust in Beijing. Affected by the application of snow-melting agents in Beijing during winter, the amount of Cl( - ) and Na( + ) was much higher during that time than in the other seasons. This will have a certain influence on roads, bridges, vegetations, and groundwater. PMID:21559919

  2. Impact of soil and dust lead on children's blood lead on Children's blood lead in contaminated areas of Sweden

    SciTech Connect

    Berglund, M.; Lind, B.; Soerensen, S.; Vahter, M.

    2000-04-01

    The impact of lead in soil and dust on blood lead concentrations in young children and the risk of health effects were investigated in an urban and a mining areas of Sweden. Blood, soil, and indoor dust, as well as information on lead-exposure factors, were collected. The blood lead concentrations (total range = 9--77 {micro}g/l) the authors measured indicated a low risk for lead-induced health effects. Lead in soil and in dust had little effect on blood lead concentrations, given the present conditions and present concentration range--especially in the mining area. Urban children had significantly higher blood lead concentrations that children in the mining area, despite higher concentrations of lead in soil in the mining area. In the urban children, blood lead concentrations were influenced by parental smoking and lead in dust at day-care centers.

  3. [The contamination of vegetable foods by lead containing street dust].

    PubMed

    Auermann, E; Börtitz, S

    1977-01-01

    To assess the contamination of fruit and vegetables by lead-containing road dust, products displayed in the open air and in retail shops, respectively, were analysed for lead content. The lead exposure within the range of the retail shop was characterized by an aerosol with 0.2-2.5 microgram/m3 and a sedimentable lead dust of 2.13-6.55 mg/m2-30 d. The lead content of the products displayed in the open air was some 0.5 to 6-fold higher. This difference was statistically significant. 92-100% of the lead dust could be removed from the products by washing with water. Increased lead contents were also found on fruit stored in a cellar (0.66 and 0.42 p.p.m., respectively) near a parking place. In consideration of the proportion of these foods in the diet consumed, no health hazard to the population can be deduced from these data; but in single cases, a temporary rise of the blood-lead level may occur. Covering fruit and vegetables presented in the open air with thin-sheet plastics or selling such products in plastics bags will prevent contamination. PMID:609359

  4. Lead exposure in young children from dust and soil in the United Kingdom

    SciTech Connect

    Thornton, I.; Watt, J.M. ); Davies, D.J.A.; Quinn, M.J. )

    1990-11-01

    A survey of metals in United Kingdom dusts and soils has confirmed widespread lead contamination with a geometric mean value for lead in surface (0-5 cm) garden soils of 266 {mu}g/g and in housedusts of 561 {mu}g/g (excluding old mining areas). A subsequent detailed survey of 97 householders in Birmingham with 2-year-old children showed dust lead loading in the home environment to be an important predictor of blood lead concentrations in young children, when both variables fell within the normal range for the UK. The total estimated lead uptake by the young child was 36 {mu}g/day of which 1 {mu}g was by inhalation and 35 {mu}g by ingestion.

  5. Removal of lead contaminated dusts from hard surfaces.

    PubMed

    Lewis, Roger D; Condoor, Sridhar; Batek, Joe; Ong, Kee Hean; Backer, Denis; Sterling, David; Siria, Jeff; Chen, John J; Ashley, Peter

    2006-01-15

    Government guidelines have widely recommended trisodium phosphate (TSP) or "lead-specific" cleaning detergents for removal of lead-contaminated dust (LCD) from hard surfaces, such as floors and window areas. The purpose of this study was to determine if low-phosphate, non-lead-specific cleaners could be used to efficiently remove LCD from 3 types of surfaces (vinyl flooring, wood, and wallpaper). Laboratory methods were developed and validated for simulating the doping, embedding, and sponge cleaning of the 3 surface types with 4 categories of cleaners: lead-specific detergents, nonionic cleaners, anionic cleaners, and trisodium phosphate (TSP). Vinyl flooring and wood were worn using artificial means. Materials were ashed, followed by ultrasound extraction, and anodic stripping voltammetry (ASV). One-way analysis of variance approach was used to evaluate the surface and detergent effects. Surface type was found to be a significant factor in removal of lead (p < 0.001). Vinyl flooring cleaned better than wallpaper by over 14% and wood cleaned better than wallpaper by 13%. There was no difference between the cleaning action of vinyl flooring and wood. No evidence was found to support the use of TSP or lead-specific detergents over all-purpose cleaning detergents for removal of lead-contaminated dusts. No-phosphate, non-lead-specific detergents are effective in sponge cleaning of lead-contaminated hard surfaces and childhood lead prevention programs should consider recommending all-purpose household detergents for removal of lead-contaminated dust after appropriate vacuuming. PMID:16468407

  6. Microchemical investigations of dust emitted by a lead smelter

    SciTech Connect

    Sobanska, S.; Ricq, N.; Laboudigue, A.; Guillermo, R.; Bremard, C.; Laureyns, J.; Merlin, J.C.; Wignacourt, J.P.

    1999-05-01

    Dusts emitted by an important pyrometallurgical lead smelter have been sampled within the pipes of the grilling and furnace working units before and after the filtering systems, respectively. Particle size distribution, elementary analyses, and X-ray powder diffraction analysis indicate PbS, PbSO{sub 4}, PbSO{sub 4}{center_dot}PbO, Pb, ZnS small particles less than 5 {micro}m in size to contribute mainly to the current atmospheric pollution. Although at least 90% of dust are retained on the filters, the amounts of the respirable smaller particles are significantly larger in the current emission. The average chemical speciation was found to be analogous for the dust samples collected before and after the filters. The scanning electron microscopy associated with energy-dispersive X-ray analysis and Raman microspectrometry established the morphology and chemical composition at the level of individual particles. A lot of minor compounds were found as small heterogeneous individual particles in the heterogeneous particles of grilling dust. Among the homogeneous particles of furnace dust, amorphous C, {beta}-PbO, PbO-PbCl{sub 2}, FeO, CdS, CdSO{sub 4} were often detected as homogeneous mixtures with the major compounds within the particles.

  7. Do new wipe materials outperform traditional lead dust cleaning methods?

    PubMed

    Lewis, Roger D; Ong, Kee Hean; Emo, Brett; Kennedy, Jason; Brown, Christopher A; Condoor, Sridhar; Thummalakunta, Laxmi

    2012-01-01

    Government guidelines have traditionally recommended the use of wet mopping, sponging, or vacuuming for removal of lead-contaminated dust from hard surfaces in homes. The emergence of new technologies, such as the electrostatic dry cloth and wet disposable clothes used on mopheads, for removal of dust provides an opportunity to evaluate their ability to remove lead compared with more established methods. The purpose of this study was to determine if relative differences exist between two new and two older methods for removal of lead-contaminated dust (LCD) from three wood surfaces that were characterized by different roughness or texture. Standard leaded dust, <75 μm, was deposited by gravity onto the wood specimens. Specimens were cleaned using an automated device. Electrostatic dry cloths (dry Swiffer), wet Swiffer cloths, paper shop towels with non-ionic detergent, and vacuuming were used for cleaning LCD from the specimens. Lead analysis was by anodic stripping voltammetry. After the cleaning study was conducted, a study of the coefficient of friction was performed for each wipe material. Analysis of variance was used to evaluate the surface and cleaning methods. There were significant interactions between cleaning method and surface types, p = 0.007. Cleaning method was found be a significant factor in removal of lead, p <0.001, indicating that effectiveness of each cleaning methods is different. However, cleaning was not affected by types of surfaces. The coefficient of friction, significantly different among the three wipes, is likely to influence the cleaning action. Cleaning method appears to be more important than texture in LCD removal from hard surfaces. There are some small but important factors in cleaning LCD from hard surfaces, including the limits of a Swiffer mop to conform to curved surfaces and the efficiency of the wetted shop towel and vacuuming for cleaning all surface textures. The mean percentage reduction in lead dust achieved by the

  8. Observed high aerosol loading during dust events in Delhi

    NASA Astrophysics Data System (ADS)

    Singh, Khem; Aggarwal, Shankar G.; Jha, Arvind K.; Singh, Nahar; Soni, Daya; Gupta, Prabhat K.

    2012-07-01

    The present study reports aerosol mass loadings and their chemical property during integrated campaign for aerosol and radiation budget (ICARB) in the month of March to May 2006, at NPL, New Delhi. The Thar Desert in Rajasthan is located on the western end of India and south-west of Delhi is hot and arid region with intense aeolian activity and transport of aerosol by the prevailing southwest-west summer wind. Several dust episodes were observed in Delhi during summer 2006. The dust storm peaked on 29th April, 1 ^{st} and 8 ^{th} May 2006, with very high suspended particulate matter (SPM) concentrations 1986μg/m ^{3}, 1735μg/m ^{3} and 1511μg/m ^{3}, respectively. The average concentration of SPM in the month of March, April and May 2006 was 338 μg/m ^{3}, 698 μg/m ^{3} and 732 μg/m ^{3}, respectively. The SPM filter samples were analysed for water-soluble major cations (Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+}) by atomic absorption spectrophotometry (AAS). Na ^{+} and Ca ^{2+} contribute about 54% and 20%, respectively of the total identified cation mass, indicating that they were most abundant cations. Strong correlations between Na ^{+}, Ca ^{2+}, K ^{+}, and Mg ^{2+} suggest their soil and dust origin. Such a high particle concentration observed during dust events may also be useful for study the effect of these aerosols on communication medium.

  9. Influence of Dust Loading on Atmospheric Ionizing Radiation on Mars

    NASA Technical Reports Server (NTRS)

    Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

    2014-01-01

    Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

  10. Influence of dust loading on atmospheric ionizing radiation on Mars

    NASA Astrophysics Data System (ADS)

    Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

    2014-01-01

    Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

  11. Lead concentration in Hong Kong roadside dust after reduction of lead level in petrol

    SciTech Connect

    Chan, G.Y.; Chui, V.W.; Wong, M.H. )

    1989-06-01

    Samples of roadside dust were collected from 30 sites in Hong Kong. The total concentrations of 10 metals in the samples were analyzed, and the correlation coefficients among the metal contents and the annual average daily traffic (AADT) in 1986 were determined. Pb was found to have a significant correlation (P less than 0.01) with AADT. No correlation was found between Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, and Zn with respect to AADT. A general decrease in the level of Pb in roadside dust in the past few years has been observed since the reduction in the level of lead in petrol.

  12. 42 CFR 84.1152 - Silica dust loading test; respirators designed as protection against dusts, fumes, and mists...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having an air contamination level less than 0.05 milligram per... air contamination level less than 0.05 milligram per cubic meter and against radionuclides;...

  13. 42 CFR 84.1152 - Silica dust loading test; respirators designed as protection against dusts, fumes, and mists...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having an air contamination level less than 0.05 milligram per... air contamination level less than 0.05 milligram per cubic meter and against radionuclides;...

  14. 42 CFR 84.1152 - Silica dust loading test; respirators designed as protection against dusts, fumes, and mists...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Silica dust loading test; respirators designed as protection against dusts, fumes, and mists having an air contamination level less than 0.05 milligram per... air contamination level less than 0.05 milligram per cubic meter and against radionuclides;...

  15. Dust-metal Loadings and the Risk of Childhood Acute Lymphoblastic Leukemia

    PubMed Central

    Whitehead, Todd P.; Ward, Mary H.; Colt, Joanne S.; Dahl, Gary; Ducore, Jonathan; Reinier, Kyndaron; Gunier, Robert B.; Hammond, S. Katharine; Rappaport, Stephen M.; Metayer, Catherine

    2015-01-01

    We evaluated the relationship between the risk of childhood acute lymphoblastic leukemia (ALL) and levels of metals in carpet dust. A dust sample was collected from the homes of 142 ALL cases and 187 controls participating in the California Childhood Leukemia Study using a high volume small surface sampler (2001–2006). Samples were analyzed using microwave-assisted acid digestion in combination with inductively-coupled plasma mass spectrometry for arsenic, cadmium, chromium, copper, lead, nickel, tin, tungsten, and zinc. Eight metals were detected in at least 85% of the case and control homes; tungsten was detected in less than 15% of homes. Relationships between dust-metal loadings (μg metal per m2 carpet) and ALL risk were modeled using multivariable logistic regression, adjusting for the child’s age, sex, and race/ethnicity and confounders, including household annual income. A doubling of dust-metal loadings was not associated with significant changes in ALL risk [odds ratio (95% confidence interval): arsenic: 0.94 (0.83, 1.05), cadmium: 0.91 (0.80, 1.04), chromium: 0.99 (0.87, 1.12), copper: 0.96 (0.90, 1.03), lead: 1.01 (0.93, 1.10), nickel: 0.92 (0.80, 1.07), tin: 0.93 (0.82, 1.05), and zinc: 0.91 (0.81, 1.02)]. Our findings do not support the hypothesis that metals in carpet dust are risk factors for childhood ALL. PMID:25736162

  16. Evolution of efficient methods to sample lead sources, such as house dust and hand dust, in the homes of children

    SciTech Connect

    Que Hee, S.S.; Peace, B.; Clark, C.S.; Boyle, J.R.; Bornschein, R.L.; Hammond, P.B.

    1985-10-01

    Efficient sampling methods to recover lead-containing house dust and hand dust have been evolved so that sufficient lead is collected for analysis and to ensure that correlational analyses linking these two parameters to blood lead are not dependent on the efficiency of sampling. Precise collection of loose house dust from a 1-unit area (484 cmS) with a Tygon or stainless steel sampling tube connected to a portable sampling pump (1.2 to 2.5 liters/min) required repetitive sampling (three times). The Tygon tube sampling technique for loose house dust <177 m in diameter was around 72% efficient with respect to dust weight and lead collection. A representative house dust contained 81% of its total weight in this fraction. A single handwipe for applied loose hand dust was not acceptably efficient or precise, and at least three wipes were necessary to achieve recoveries of >80% of the lead applied. House dusts of different particle sizes <246 m adhered equally well to hands. Analysis of lead-containing material usually required at least three digestions/decantations using hot plate or microwave techniques to allow at least 90% of the lead to be recovered. It was recommended that other investigators validate their handwiping, house dust sampling, and digestion techniques to facilitate comparison of results across studies. The final methodology for the Cincinnati longitudinal study was three sampling passes for surface dust using a stainless steel sampling tube; three microwave digestion/decantations for analysis of dust and paint; and three wipes with handwipes with one digestion/decantation for the analysis of six handwipes together.

  17. Tungsten dust in fusion tokamaks: relevant dust laser production, characterization and behaviour under tritium loading

    NASA Astrophysics Data System (ADS)

    Bernard, E.; Delaporte, P.; Jambon, F.; Rousseau, B.; Grisolia, C.; Chaudanson, D.; Nitsche, S.

    2016-02-01

    In this paper, production and study of tokamak relevant W particles is presented. Existing tokamak-produced dust being very scarce, extensive study of such nano-particles with high specific surface area (SSA) and sub micron size requires a specific and efficient alternative production technique, in order to obtain relevant particles to study. We present our production and collection setup based on pulsed laser ablation on bulk ITER-grade tungsten, and the various parameters impacting on the collected dust morphology and properties. We observed that optimum gas pressure is required to control the laser-induced plasma properties and favour the production of tungsten nano-particles with high SSA. The laser pulse duration is also a key parameter to limit the generation of tungsten liquid droplets during the ablation process. The nano-particules structure and general aspect are characterized via scanning electron microscopy and transmission electron microscopy. Lastly, this dust produced by laser ablation is loaded with tritium by gas exposure, and its retention capability and long-term evolution addressed and compared to metallurgically produced W powders with homogeneous size distribution.

  18. Evaluation of four sampling methods for determining exposure of children to lead-contaminated household dust

    SciTech Connect

    Sterling, D.A.; Roegner, K.C.; Lewis, R.D.; Luke, D.A. . Div. of Environmental and Occupational Health); Wilder, L.C. . Div. of Health Assessment and Consultation); Burchette, S.M. )

    1999-08-01

    Childhood exposure to lead has been demonstrated to result in health effects and lead-contaminated household dust is a primary exposure source. There is a need to establish reliable methods for sampling surfaces to determine levels of lead contamination. Three vacuums (HVS3, GS80, and MVM) and one wipe method were evaluated for the collection of household floor dust under field sampling conditions within a Superfund site and demographically similar control area. Side-by-side floor samples were taken from three locations within 41 randomly selected households between August and September 1995: a child's bedroom, primary play area, and primary entrance. Analysis was performed to assess the relative collection performance of each sampler, spatial distribution of lead within a household, and correlation of lead loading with observed blood lead level, and to determine if discrete or composites samples were more predictive of blood lead levels. Approximately 90% of the floor surfaces were carpeted. The rank order of sampling methods from greatest to lowest collection efficiency was HVS3 > G80 > wipe > MVM. The HVS3 had the highest level of precision (CV = 0.05), with the GS80 and wipe precisions 0.48 and 0.053, respectively.

  19. Manganese and lead in dust fall accumulation in elementary schools near a ferromanganese alloy plant.

    PubMed

    Menezes-Filho, José Antonio; Souza, Karine O Fraga de; Rodrigues, Juliana L Gomes; Santos, Nathália Ribeiro Dos; Bandeira, Matheus de Jesus; Koin, Ng Lai; Oliveira, Sérgio S do Prado; Godoy, Ana Leonor P Campos; Mergler, Donna

    2016-07-01

    Previous studies have shown elevated airborne manganese (Mn) in villages adjacent to a Mn alloy production plant in Brazil and negative associations between biomarkers of Mn and children's cognition and behavior. Since small Mn particles may be carried for long distances, we measured manganese (Mn) and lead (Pb) dust fall accumulation in 15 elementary schools, located between 1.25 and 6.48km from the plant in the municipality of Simões Filho, Bahia, Brazil. Passive samplers (polyethylene Petri dishes) were set in interior and exterior environments. After 30 days, the samplers' content was solubilized with diluted nitric acid and Mn and Pb levels were analyzed by electrothermal absorption spectrometry. The overall geometric mean and range of Mn and Pb accumulation in dust fall (loading rates) were 1582μg Mn/m(2)/30 days (37-37,967) and 43.2μg Pb/m(2)/30 days (2.9-210.4). A logarithmic decrease in interior and exterior Mn loading rates was observed with distance from the ferro-manganese alloy plant. Multiple regression analyses of log-transformed Mn loading rate within the schools showed a positive association with Mn levels in outdoor dust, a negative association with distance from the plant; as well, wind direction (downwind>upwind) and school location (urban>rural) entered significantly into the model. For the interior school environments, located within a 2-km radius from the plant, loading rate was, on average, 190 times higher than the Mn levels reported by Gulson et al., (2014) in daycare centers in Sydney, Australia, using a similar method. Pb loading rates were not associated with distance from the plant and were lower than the rates observed in the same daycare centers in Sydney. Our findings suggest that a significant portion of the children in this town in Brazil may be exposed to airborne Mn at concentrations that may affect their neurodevelopment. PMID:27107708

  20. Influence of social and environmental factors on dust, lead, hand lead, and blood lead levels in young children

    SciTech Connect

    Bornschein, R.L.; Succop, P.; Dietrich, K.N.; Clark, C.S.; Que Hee, S.; Hammond, P.B.

    1985-10-01

    The roles of environmental and behavioral factors in determining blood lead levels were studied in a cohort of young children living in an urban environment. The subjects were observed at 3-month intervals from birth to 24 months of age. Repeated measurements were made of the children's blood lead levels, environmental levels of lead in house dust, and in the dust found on the children's hands. A qualitative rating of the residence and of the socioeconomic status of the family was obtained. Interviews and direct observation of parent and child at home were used to evaluate various aspects of caretaker-child interactions. Data analysis consisted of a comparison of results obtained by (a) simple correlational analysis, (b) multiple regression analysis, and (c) structural equations analysis. The results demonstrated that structural equation modeling offers a useful approach to unraveling the complex interactions present in the data set. In this preliminary analysis, the suspected relationship between the levels of lead in house dust and on hands and the blood lead level was clearly demonstrated. Furthermore, the analyses indicated an important interplay between environmental sources and social factors in the determination of hand lead and blood lead levels in very young children.

  1. Factors affecting lead, cadmium, and arsenic levels in house dust in a smelter town in eastern Germany

    SciTech Connect

    Meyer, I.; Heinrich, J. . Inst. fuer Epidemiologie); Lippold, U. )

    1999-07-01

    Hettstedt, a city in eastern Germany with a long history of mining and smelting of nonferrous ores, has several industrial sources of heavy metals. The indoor exposure to metals of children (5 to 14 years old) in the Hettstedt area was assessed by measuring the levels of lead, cadmium, and arsenic contamination in sedimented house dust. Factors which influence the dust loading rate and the surface loading rates of these contaminants in house dust were investigated. The geometric mean of the dust loading rate was 8.9 mg/m[sup 2] day. The geometric means of surface loading rates were 1.14, 0.024, and 0.023 [micro]g/m[sup 2] day for lead, cadmium, and arsenic, respectively. Factors that were significantly associated with surface loading rates included the city area of residence, automobile traffic near home, parent with occupational exposure to heavy metals, type of heating, housing characteristics, whether child's home is damp, number of persons living in the child's home,and parents' education. The most significant of these factors was the city area of residence, which reflects the distance from the metal sources; this factor accounted for about half of the variances explained by the regression models.

  2. Comparison of techniques to reduce residential lead dust on carpet and upholstery: the new jersey assessment of cleaning techniques trial.

    PubMed

    Yiin, Lih-Ming; Rhoads, George G; Rich, David Q; Zhang, Junfeng; Bai, Zhipeng; Adgate, John L; Ashley, Peter J; Lioy, Paul J

    2002-12-01

    High-efficiency particulate air (HEPA) filtered vacuum cleaners are recommended by the U.S. Department of Housing and Urban Development for cleaning lead-contaminated house dust. We performed a randomized field study to determine whether a conventional (non-HEPA) vacuum cleaner could achieve cleaning results comparable with those of a HEPA vacuum cleaner. We compared the lead loading reductions of these two vacuum cleaners in a total of 127 New Jersey homes of lead-exposed children. We used wet towelettes and a vacuum sampler to collect lead dust from carpets and upholstery before and after vacuum cleaning. The vacuum sampling data showed that the HEPA and non-HEPA vacuum cleaners resulted in 54.7% (p = 0.006) and 36.4% (p = 0.020) reductions in lead loading, respectively, when used on soiled carpets, although the overall difference in lead loading reduction between the two vacuum cleaners was not statistically significant (p = 0.293). The wipe sampling data did not show any significant lead loading reduction for either of the vacuum cleaners, suggesting that both vacuum cleaners fail to clean the surfaces of carpet effectively, considering that wipe sampling media simulate surface contact. On upholstery, the wipe sampling data showed a significant reduction in lead loading for the non-HEPA vacuum cleaner (22.2%, p = 0.047). Even with the significant reduction, the postcleaning lead loadings on upholstery were similar to those on carpets. The similar lead loading results for carpets and upholstery indicate that soiled upholstery may be as important a source of childhood lead exposure as carpets. PMID:12460803

  3. Comparison of techniques to reduce residential lead dust on carpet and upholstery: the new jersey assessment of cleaning techniques trial.

    PubMed Central

    Yiin, Lih-Ming; Rhoads, George G; Rich, David Q; Zhang, Junfeng; Bai, Zhipeng; Adgate, John L; Ashley, Peter J; Lioy, Paul J

    2002-01-01

    High-efficiency particulate air (HEPA) filtered vacuum cleaners are recommended by the U.S. Department of Housing and Urban Development for cleaning lead-contaminated house dust. We performed a randomized field study to determine whether a conventional (non-HEPA) vacuum cleaner could achieve cleaning results comparable with those of a HEPA vacuum cleaner. We compared the lead loading reductions of these two vacuum cleaners in a total of 127 New Jersey homes of lead-exposed children. We used wet towelettes and a vacuum sampler to collect lead dust from carpets and upholstery before and after vacuum cleaning. The vacuum sampling data showed that the HEPA and non-HEPA vacuum cleaners resulted in 54.7% (p = 0.006) and 36.4% (p = 0.020) reductions in lead loading, respectively, when used on soiled carpets, although the overall difference in lead loading reduction between the two vacuum cleaners was not statistically significant (p = 0.293). The wipe sampling data did not show any significant lead loading reduction for either of the vacuum cleaners, suggesting that both vacuum cleaners fail to clean the surfaces of carpet effectively, considering that wipe sampling media simulate surface contact. On upholstery, the wipe sampling data showed a significant reduction in lead loading for the non-HEPA vacuum cleaner (22.2%, p = 0.047). Even with the significant reduction, the postcleaning lead loadings on upholstery were similar to those on carpets. The similar lead loading results for carpets and upholstery indicate that soiled upholstery may be as important a source of childhood lead exposure as carpets. PMID:12460803

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

    SciTech Connect

    Hogervorst, Janneke; Plusquin, Michelle; Vangronsveld, Jaco; Nawrot, Tim; Cuypers, Ann; Van Hecke, Etienne; Roels, Harry A.; Carleer, Robert; Staessen, Jan A. . E-mail: jan.staessen@med.kuleuven.be

    2007-01-15

    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. 0.24{mu}mol/L), the loading rates of cadmium and lead in house dust (0.29 vs. 0.12 and 7.52 vs. 3.62ng/cm{sup 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.

  5. Provenance of dust to Antarctica: A lead isotopic perspective

    NASA Astrophysics Data System (ADS)

    Gili, Stefania; Gaiero, Diego M.; Goldstein, Steven L.; Chemale, Farid, Jr.; Koester, Edinei; Jweda, Jason; Vallelonga, Paul; Kaplan, Michael R.

    2016-03-01

    Antarctic ice preserves an ~800 kyr record of dust activity in the Southern Hemisphere. Major efforts have been dedicated to elucidate the origin of this material in order to gain greater insight into the atmospheric dust cycle. On the basis of Pb isotopes in Antarctic dust samples and potential sources, this contribution demonstrates for the first time that Patagonia is the main contributor of dust to Antarctica during interglacial periods as well as glacials, although the potential importance of Tierra del Fuego remains unclear because of its geochemical similarities to Patagonia. An important new finding is that the Puna-Altiplano sector of the continent is a second important dust source to eastern Antarctica during both glacials and interglacials, being more prominent during interglacials. The data indicate South America is the primary dust source to Antarctica during both glacials and interglacials.

  6. Development and field trial of a household surface lead loading rate sampling device in a lead-contaminated community of southern Thailand.

    PubMed

    Untimanon, Orrapan; Geater, Alan; Chongsuvivatwong, Virasakdi; Thoumsang, Somkiat; Verkasalo, Pia K; Saetia, Wiyada

    2010-05-01

    A new dust-collecting device was developed to assess surface lead loading rates in houses in communities contaminated with lead oxide dust used for caulking in nearby boat-repair yards. The device consists of two small glass sheets with total area of 1,200 cm(2) placed in two plastic trays suspended from the ceiling in the house for 3 months before wiping and sending the dust specimen for determination of lead content using flame atomic absorption spectrophotometry. After a pilot trial in four households, further data were collected from 43 matched pairs of boat-caulkers' and neighboring control households. All devices were retained in the house for 3 months without any complaint. Static measurements of lead dust levels were also assessed in all households. The values significantly discriminated high from low lead exposure households (p = 0.015) and provided good correlations with floor lead loading (Spearman rank correlation coefficient, r = 0.39 to 0.62) and dust lead content (r = 0.53 to 0.64). This sampling method is an alternative to others which consume more household space or require a longer collection period. PMID:19415518

  7. Estimating outdoor and indoor dust lead levels from accidental bridge repair containment releases

    SciTech Connect

    Cohen, J.T.; Conway, R.F.

    1999-07-01

    A 1998 New York City Department of Transportation (NYCDOT) environmental impact statement (EIS) evaluated the proposed removal of deteriorated lead paint from NYCDOT-owned bridges. The EIS health risk assessment quantified the potential impact of particulate releases on blood lead levels among members of the public living and working near affected bridges. The risk assessment consisted of a fate and transport component and an exposure-dose component. The fate and transport component, modeled using the EPA's Industrial Source Complex (ISC3) model, calculated the impact of paint removal activities on ambient air lead concentrations and dust lead deposition rates. The exposure-dose component, modeled using EPA's Integrated Exposure Uptake Biokinetic (IEUBK) model, the Bowers et al. Adult Lead model, and the O'Flaherty lead model, calculated the impact of additional lead in air, street dust, interior house dust, and soil on blood lead levels, a conventional measure of body lead burden. The analysis was complicated because the ISC3 model provides a dust lead deposition rate ({micro}g/m{sup 2}-day), while the IEUBK, Bowers et al., and O'Flaherty models demand as input specification of dust lead concentrations ({micro}g lead per g dust). This paper describes a model developed for the EIS that quantifies long term average dust lead concentrations associated with typical bridge containment releases, and short term dust lead concentration spikes following worst case release events associated with bridge repair containment structure failures. The model reflects the influence of both lead and other debris associated with bridge repair activities, the contribution of background debris to street dust, and the impact of rainfall on removal of both lead and other material from the street dust reservoir.

  8. Lead and zinc dust depositions from ore trains characterised using lead isotopic compositions.

    PubMed

    Kristensen, L J; Taylor, M P; Morrison, A L

    2015-03-01

    This study investigates an unusual source of environmental lead contamination - the emission and deposition of lead and zinc concentrates along train lines into and out of Australia's oldest silver-lead-zinc mine at Broken Hill, Australia. Transport of lead and zinc ore concentrates from the Broken Hill mines has occurred for more than 125 years, during which time the majority was moved in uncovered rail wagons. A significant amount of ore was lost to the adjoining environments, resulting in soil immediately adjacent to train lines elevated with concentrations of lead (695 mg kg(-1)) and zinc (2230 mg kg(-1)). Concentrations of lead and zinc decreased away from the train line and also with depth shown in soil profiles. Lead isotopic compositions demonstrated the soil lead contained Broken Hill ore in increasing percentages closer to the train line, with up to 97% apportioned to the mined Broken Hill ore body. SEM examination showed ceiling dusts collected from houses along the train line were composed of unweathered galena particles, characteristic of the concentrate transported in the rail wagons. The loss of ore from the uncovered wagons has significantly extended the environmental footprint of contamination from local mining operations over an area extending hundreds of kilometres along each of the three train lines. PMID:25627173

  9. Lake Michigan sediment lead storage and history of loads

    EPA Science Inventory

    Dated sediment box cores collected in 1994-1996 from 52 locations in Lake Michigan were analyzed for to access storage, trends, and loading history of lead. The results of this study provide information of historic lead loads to the lake for a time period for which no other info...

  10. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist... oxygen-gas flame on molten lead. (e) Samples of the test suspension will be taken during each test...

  11. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist... oxygen-gas flame on molten lead. (e) Samples of the test suspension will be taken during each test...

  12. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist... oxygen-gas flame on molten lead. (e) Samples of the test suspension will be taken during each test...

  13. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist... oxygen-gas flame on molten lead. (e) Samples of the test suspension will be taken during each test...

  14. Characterization of lead, chromium, and cadmium in dust emitted from municipal solid waste incineration plants

    NASA Astrophysics Data System (ADS)

    Shiota, K.; Imai, G.; Oshita, K.; Takaoka, M.

    2013-04-01

    The dust is emitted from municipal solid waste incinerators (MSWIs). Volatile toxic heavy metals are abundant in smaller dust particles and influence the toxicity of particulate matter such as fine particles <2.5 μm (PM2.5). However, little is known about the properties of these metals in fine dust particles. Therefore, X-ray absorption fine structure (XAFS) spectroscopy was used to investigate the chemical states of lead (Pb), chromium (Cr), and cadmium (Cd) in MSWI dust collected for nine particle size fractions at the inlet of the dust collector and the stacks of two MSWI plants. XAFS spectroscopy of the dust in the inlet of the dust collectors showed that finer dust contained predominantly Pb as PbCl2 with some PbSiO3, coarser dust consisted of Cr forms, including more toxic Cr(VI) species, and all dust contained CdCl2. Although the dust collector removed almost all of the Pb, trace amounts of PbCl2 remained in the stack gas after passing through the dust collector.

  15. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions.

    PubMed

    Murphy, Gillian; Greene, Ciara M

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

  16. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

    PubMed Central

    Murphy, Gillian; Greene, Ciara M.

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

  17. Mars: Correcting surface albedo observations for effects of atmospheric dust loading

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    We have developed a radiative transfer model which allows the effects of atmospheric dust loading on surface albedo to be investigated. This model incorporates atmospheric dust opacity, the single scattering albedo and particle phase function of atmospheric dust, the bidirectional reflectance of the surface, and variable lighting and viewing geometry. The most recent dust particle properties are utilized. The spatial and temporal variability of atmospheric opacity (Tan) strongly influences the radiative transfer modelling results. We are currently using the approach described to determine Tan for IRTM mapping sequences of selected regions. This approach allows Tan to be determined at the highest spatial and temporal resolution supported by the IRTM data. Applying the radiative transfer modelling and determination of Tan described, IRTM visual brightness observations can be corrected for the effects of atmospheric dust loading a variety of locations and times. This approach allows maps of 'dust-corrected surface albedo' to be constructed for selected regions. Information on the variability of surface albedo and the amount of dust deposition/erosion related to such variability results. To date, this study indicates that atmospheric dust loading has a significant effect on observations of surface albedo, amounting to albedo corrections of as much as several tens of percent. This correction is not constant or linear, but depends upon surface albedo, viewing and lighting geometry, the dust and surface phase functions, and the atmospheric opacity. It is clear that the quantitative study of surface albedo, especially where small variations in observed albedo are important (such as photometric analyses), needs to account for the effects of the atmospheric dust loading. Maps of 'dust-corrected surface albedo' will be presented for a number of regions.

  18. Surface dust wipes are the best predictors of blood leads in young children with elevated blood lead levels

    SciTech Connect

    Gulson, Brian; Anderson, Phil; Taylor, Alan

    2013-10-15

    Background: As part of the only national survey of lead in Australian children, which was undertaken in 1996, lead isotopic and lead concentration measurements were obtained from children from 24 dwellings whose blood lead levels were ≥15 µg/dL in an attempt to determine the source(s) of their elevated blood lead. Comparisons were made with data for six children with lower blood lead levels (<10 µg/dL). Methods: Thermal ionisation and isotope dilution mass spectrometry were used to determine high precision lead isotopic ratios ({sup 208}Pb/{sup 206}Pb, {sup 207}Pb/{sup 206}Pb and {sup 206}Pb/{sup 204}Pb) and lead concentrations in blood, dust from floor wipes, soil, drinking water and paint (where available). Evaluation of associations between blood and the environmental samples was based on the analysis of individual cases, and Pearson correlations and multiple regression analyses based on the whole dataset. Results and discussion: The correlations showed an association for isotopic ratios in blood and wipes (r=0.52, 95% CI 0.19–0.74), blood and soil (r=0.33, 95% CI −0.05–0.62), and blood and paint (r=0.56, 95% CI 0.09–0.83). The regression analyses indicated that the only statistically significant relationship for blood isotopic ratios was with dust wipes (B=0.65, 95% CI 0.35–0.95); there were no significant associations for lead concentrations in blood and environmental samples. There is a strong isotopic correlation of soils and house dust (r=0.53, 95% CI 0.20–0.75) indicative of a common source(s) for lead in soil and house dust. In contrast, as with the regression analyses, no such association is present for bulk lead concentrations (r=−0.003, 95% CI −0.37–0.36), the most common approach employed in source investigations. In evaluation of the isotopic results on a case by case basis, the strongest associations were for dust wipes and blood. -- Highlights: • Children with elevated blood lead ≥15 µg/dL compared with a group with <10

  19. Lead and Other Heavy Metals in Dust Fall from Single-Family Housing Demolition

    PubMed Central

    Cali, Salvatore; Welch, Alison; Catalin, Bogdan; Dixon, Sherry L.; Evens, Anne; Mucha, Amy P.; Vahl, Nicole; Erdal, Serap; Bartlett, John

    2013-01-01

    Objective We measured lead and other heavy metals in dust during older housing demolition and effectiveness of dust suppression. Methods We used American Public Housing Association Method 502 and U.S. Environmental Protection Agency Methods SW3050B and SW6020 at 97 single-family housing demolition events with intermittent (or no) use of water to suppress dust at perimeter, non-perimeter, and locations without demolition, with nested mixed modeling and tobit modeling with left censoring. Results The geometric mean (GM) lead dust fall during demolition was 6.01 micrograms of lead per square foot per hour (μg Pb/ft2/hour). GM lead dust fall was 14.18 μg Pb/ft2/hour without dust suppression, but declined to 5.48 μg Pb/ft2/hour (p=0.057) when buildings and debris were wetted. Significant predictors included distance, wind direction, and main street location. At 400 feet, lead dust fall was not significantly different from background. GM lead concentration at demolition (2,406 parts per million [ppm]) was significantly greater than background (GM=579 ppm, p=0.05). Arsenic, chromium, copper, iron, and manganese demolition dust fall was significantly higher than background (p<0.001). Demolition of approximately 400 old housing units elsewhere with more dust suppression was only 0.25 μg Pb/ft2/hour. Conclusions Lead dust suppression is feasible and important in single-family housing demolition where distances between houses are smaller and community exposures are higher. Neighbor notification should be expanded to at least 400 feet away from single-family housing demolition, not just adjacent properties. Further research is needed on effects of distance, potential water contamination, occupational exposures, and water application. PMID:24179257

  20. Canadian House Dust Study: Lead Bioaccessibility and Speciation

    SciTech Connect

    P Rasmussen; S Beauchemin; M Chenier; C Levesque; L MacLean; L Marrow; H Jones-Otazo; S Petrovic; L McDonald; H Gardner

    2011-12-31

    Vacuum samples were collected from 1025 randomly selected urban Canadian homes to investigate bioaccessible Pb (Pb{sub S}) concentrations in settled house dust. Results indicate a polymodal frequency distribution, consisting of three lognormally distributed subpopulations defined as 'urban background' (geomean 58 {micro}g g{sup -1}), 'elevated' (geomean 447 {micro}g g{sup -1}), and 'anomalous' (geomean 1730 {micro}g g{sup -1}). Dust Pb{sub S} concentrations in 924 homes (90%) fall into the 'urban background' category. The elevated and anomalous subpopulations predominantly consist of older homes located in central core areas of cities. The influence of house age is evidenced by a moderate correlation between house age and dust Pb{sub S} content (R{sup 2} = 0.34; n = 1025; p < 0.01), but it is notable that more than 10% of homes in the elevated/anomalous category were built after 1980. Conversely, the benefit of home remediation is evidenced by the large number of homes (33%) in the background category that were built before 1960. The dominant dust Pb species determined using X-ray Absorption Spectroscopy were as follows: Pb carbonate, Pb hydroxyl carbonate, Pb sulfate, Pb chromate, Pb oxide, Pb citrate, Pb metal, Pb adsorbed to Fe- and Al-oxyhydroxides, and Pb adsorbed to humate. Pb bioaccessibility estimated from solid phase speciation predicts Pb bioaccessibility measured using a simulated gastric extraction (R{sup 2} = 0.85; n = 12; p < 0.0001). The trend toward increased Pb bioaccessibility in the elevated and anomalous subpopulations (75% {+-} 18% and 81% {+-} 8%, respectively) compared to background (63% {+-} 18%) is explained by the higher proportion of bioaccessible compounds used as pigments in older paints (Pb carbonate and Pb hydroxyl carbonate). This population-based study provides a nationally representative urban baseline for applications in human health risk assessment and risk management.

  1. Dust Weight and Asthma Prevalence in the National Survey of Lead and Allergens in Housing (NSLAH)

    PubMed Central

    Elliott, Leslie; Arbes, Samuel J.; Harvey, Eric S.; Lee, Robert C.; Salo, Päivi M.; Cohn, Richard D.; London, Stephanie J.; Zeldin, Darryl C.

    2007-01-01

    Background Settled dust has been used in studies to assess exposures to allergens and other biologically active components, but it has not been considered in the aggregate in relation to respiratory health outcomes in the general population. Objective We addressed whether total house dust weight, an index of total dust exposure, was associated with respiratory health outcomes in the National Survey of Lead and Allergens in Housing (1998–1999) (NSLAH). Methods NSLAH was a cross-sectional survey designed to represent permanently occupied housing units in the United States. In each household, a questionnaire was administered and settled dust was vacuumed from five locations. Linear regression models were used to identify predictors of dust weight; logistic regression models were used to examine the relationship between dust weight and asthma and wheeze. Results Dust weight samples were available for 829 households, and survey information was available for 2,456 participants (children and adults). Lower income, older homes, household pets, having a smoker in the house, and less frequent cleaning predicted higher dust weight levels in U.S. households. Higher levels of dust weight were associated with greater odds of current asthma and wheeze. The strongest associations were seen for wheeze [adjusted odds ratio (OR) = 1.99; 95% confidence interval (CI), 1.21–3.28 for bedroom bed dust; OR = 2.81; 95% CI, 1.52–5.21 for upholstery dust). These associations persisted when adjusting for allergen and endotoxin exposures. Conclusions Dust weight, an index of total dust exposure in the home, may contribute to respiratory outcomes independently of the exposure to specific components. PMID:17384767

  2. How to minimize iron loss while decontaminating converter dust from lead.

    PubMed

    Moussavi, Mohsen; Fathikalajahi, Jamshid; Khalili, Fariba

    2011-12-01

    The purpose of this work was to decontaminate a converter flue dust from lead while minimizing the iron loss from the dust matrix. A physicochemical method based on a leaching cascade was applied to remove lead impurities with HCl. Finally, the lead-rich wastes generated at the end of the operations were further treated in order to meet the standards of waste disposal sites. The results show that lead could be removed from the dust with efficiencies of better than 90%. However, some iron was lost in these operations. It was noticed that under optimum conditions 8.5 g of iron would be lost as leachate per each gram of removed lead. It was also noticed that the lead-treated dust was more concentrated in iron and had less calcium. A number of parameters that could affect the amount of iron loss, such as acid dose, exposure time and temperature, were identified and the extent of the effects are presented. It was concluded that the lead content in the flue dust could practically be lowered to any level. It was also concluded that the difference between the solubility of lead chloride in cold and hot water, as well as the affinity of certain ligands such as Cl- and OH- to form stable complexes with lead ions, played a key role in this study. The lead-containing complexes in the leachate were identified to be predominantly PbCl3- and PbCl+. PMID:22439558

  3. Simulation of the Radiative Impact of High Dust Loading during a Dust Storm in March 2012

    NASA Astrophysics Data System (ADS)

    Puthan Purakkal, J.; Kalenderski, S.; Stenchikov, G. L.

    2013-12-01

    We investigated a severe dust storm that developed over vast areas of the Middle East on 18-19 March 2012 and affected Saudi Arabia, Sudan, Egypt, Jordan, United Arab Emirates, Bahrain, Qatar, Oman, Kuwait, Iraq, Iran, Israel, and Pakistan. The visible aerosol optical depth recorded by the AERONET station on the KAUST campus (22.30o N 39.10o E) during the storm reached 4.5, exceeding the average level by an order of magnitude. To quantify the effects of the dust on atmospheric radiation and dynamics, we analyzed available ground-based and satellite observations and conducted numerical simulations using a fully coupled meteorology-chemistry-aerosol model (WRF-Chem). The model was able to reproduce the spatial and temporal patterns of the aerosol optical depths (AOD) observed by airborne and ground-based instruments. The major dust sources included river valleys of lower Tigris and Euphrates in Iraq, desert areas in Kuwait, Iran, United Arab Emirates, central Arabia including Rub' al Khali, An Nafud, and Ad Dahna, as well as the Red Sea coast of the Arabian Peninsula. The total amount of dust generated across the entire domain during the period of the simulation reached 93.76 Mt; 73.04 Mt of dust was deposited within the domain; 6.56 Mt of dust sunk in the adjacent sea waters, including 1.20 Mt that sedimented into the Red Sea. The model predicted a well-mixed boundary layer expanding up to 3.5 km in the afternoon. Some dust plumes were seen above the Planetary Boundary layer. In our simulations, mineral dust heated the lower atmosphere with a maximum heating rate of 9 K/day. The dust storm reduced the downwelling shortwave radiation at the surface to a maximum daily average value of -134 Wm-2 and the daily averaged long-wave forcing at the surface increased to 43 Wm-2. The combined short-wave cooling and long-wave warming effects of dust aerosols caused significant reduction in the surface air temperature -6.7 K at 1200 UTC on 19 March 2013.

  4. Estimation of Collection Efficiency Change of Moving Granular Bed Filter by Dust Load

    SciTech Connect

    Furuuchi, M.; Hata, M.; Kanaoka, C.; Kawaminami, Y.

    2002-09-18

    Final goal of this study is to theoretically describe effects of influencing factors on the performance of the coke bed filter as a material classifier and to predict its optimal operating condition. In this paper, the author focuses on the basic investigation on collection mechanism of a fixed coke bed filter on the basis of the depth filtration theory, in which an influence of dust load on the dust collection efficiency.

  5. Desert dust in rural western US; the influence of dust storms, large particles, and land-use change on aerosol loads

    NASA Astrophysics Data System (ADS)

    Parks, D.; MacDonald, A. E.; Rosen, R. D.; Edmonds, H. N.; Key, E.; Swanberg, N.; Wiseman, W. J.; Sandgathe, S. A.; Neff, J. C.; Fernandez, D.; Munson, S.; Reynolds, R. L.

    2011-12-01

    Atmospheric aerosols are common in urban settings as well as dryland rural environments and are important to both climate and biogeochemical cycling. Most urban and far traveled aerosols are less than 10 micrometers in diameter with many particles in the less than 2.5 or 1 micrometer-size classes. Small aerosols, including many generated by industrial activity, are the focus of federal environmental law and have a major impact on human health. In rural areas of the western US, however, these small industrially derived particles appear to make up a small part of the overall aerosol load. Rather, dust in the rural West is dominated by mineral aerosols including a large amount of particles that range in size from 10 to 40 microns. These particles can travel for hundreds of kilometers, particularly during periods when dust storms are common. In the dusty spring and summer periods in and around Canyonlands and Mesa Verde National Parks, large particles (particles greater than 10 micrometers in diameter) appear to contribute between 50 and 90% to the overall particle load several meters above the ground. During large dust storms, concentrations of total suspended particulates increase by a factor of 8 to 10 while particles less than 10 micrometers in diameter are minimally affected. The presence of large particles in the atmosphere of the rural West is notable for several reasons. First, the majority of the existing aerosol monitoring networks focus on the small particle-size classes of less than 2.5 and 10 microns. Because many aerosol-collection instruments are designed with specific particle-size cutoff criteria, these instruments and the networks that depend on them are effectively blind to the larger particles that can dominate aerosol loads in the West. Second, for large portions of the year including the spring and summer months when dust storms are common, large particles likely play a major role in visibility restrictions across the protected airsheds of the

  6. Linkages between observed, modeled Saharan dust loading and meningitis in Senegal during 2012 and 2013.

    PubMed

    Diokhane, Aminata Mbow; Jenkins, Gregory S; Manga, Noel; Drame, Mamadou S; Mbodji, Boubacar

    2016-04-01

    The Sahara desert transports large quantities of dust over the Sahelian region during the Northern Hemisphere winter and spring seasons (December-April). In episodic events, high dust concentrations are found at the surface, negatively impacting respiratory health. Bacterial meningitis in particular is known to affect populations that live in the Sahelian zones, which is otherwise known as the meningitis belt. During the winter and spring of 2012, suspected meningitis cases (SMCs) were with three times higher than in 2013. We show higher surface particular matter concentrations at Dakar, Senegal and elevated atmospheric dust loading in Senegal for the period of 1 January-31 May during 2012 relative to 2013. We analyze simulated particulate matter over Senegal from the Weather Research and Forecasting (WRF) model during 2012 and 2013. The results show higher simulated dust concentrations during the winter season of 2012 for Senegal. The WRF model correctly captures the large dust events from 1 January-31 March but has shown less skill during April and May for simulated dust concentrations. The results also show that the boundary conditions are the key feature for correctly simulating large dust events and initial conditions are less important. PMID:26296434

  7. Linkages between observed, modeled Saharan dust loading and meningitis in Senegal during 2012 and 2013

    NASA Astrophysics Data System (ADS)

    Diokhane, Aminata Mbow; Jenkins, Gregory S.; Manga, Noel; Drame, Mamadou S.; Mbodji, Boubacar

    2016-04-01

    The Sahara desert transports large quantities of dust over the Sahelian region during the Northern Hemisphere winter and spring seasons (December-April). In episodic events, high dust concentrations are found at the surface, negatively impacting respiratory health. Bacterial meningitis in particular is known to affect populations that live in the Sahelian zones, which is otherwise known as the meningitis belt. During the winter and spring of 2012, suspected meningitis cases (SMCs) were with three times higher than in 2013. We show higher surface particular matter concentrations at Dakar, Senegal and elevated atmospheric dust loading in Senegal for the period of 1 January-31 May during 2012 relative to 2013. We analyze simulated particulate matter over Senegal from the Weather Research and Forecasting (WRF) model during 2012 and 2013. The results show higher simulated dust concentrations during the winter season of 2012 for Senegal. The WRF model correctly captures the large dust events from 1 January-31 March but has shown less skill during April and May for simulated dust concentrations. The results also show that the boundary conditions are the key feature for correctly simulating large dust events and initial conditions are less important.

  8. EFFECT OF LOADING DUST TYPE ON THE FILTRATION EFFICIENCY OF ELECTROSTATICALLY CHARGED FILTERS

    EPA Science Inventory

    The paper gives results of an evaluation of the effect of loading dust type on the filtration efficiency of electrostatically charged filters. Three types of filters were evaluated: a rigid-cell filter charged using an electrodynamic spinning process, a pleated-panel filter cha...

  9. Investigation of Techniques to Improve Continuous Air Monitors Under Conditions of High Dust Loading in Environmental Settings

    SciTech Connect

    Suilou Huang; Stephen D. Schery; John C. Rodgers

    2002-07-23

    A number of DOE facilities, such as the Los Alamos National Laboratory (LANL) and the Waste Isolation Pilot Plant (WIPP), use alpha-particle environmental continuous air monitors (ECAMs) to monitor air for unwanted releases of radioactive aerosols containing such materials as plutonium and uranium. High sensitivity, ease of operation, and lack of false alarms are all important for ECAMs. The object of the project was to conduct investigations to improve operation of ECAMs, particularly under conditions where a lot of nonradioactive dust may be deposited on the filters (conditions of high dust loading). The presence of such dust may increase the frequency with which filters must be changed and can lead to an increased incidence of false alarms due to deteriorated energy resolution and response specificity to the radionuclides of interest. A major finding of the investigation, not previously documented, was that under many conditions thick layers of underlying nonradioactive dust do not decrease energy resolution and specificity for target radionuclides if the radioactive aerosol arrives as a sudden thin burst deposit, as commonly occurs in the early-warning alarm mode. As a result, operators of ECAMs may not need to change filters as often as previously thought and have data upon which to base more reliable operating procedures.

  10. Improving radiative transfer processes in snow-covered areas prone to dust loading using a regional climate model

    NASA Astrophysics Data System (ADS)

    Oaida, C. M.; Xue, Y.; Painter, T. H.; Flanner, M. G.; De Sales, F.

    2011-12-01

    Radiative processes play an important role on both global and regional scales. This study focuses on their effects over snow-covered surfaces, both clean and dust loaded. It is well understood that dust in snow enhances solar radiation absorption, leading to a decrease in snow albedo. However, the quantitative assessment of dust's influence on radiative forcing and runoff timing in mountain snow packs has only been recently investigated. Painter et al. (2007) have shown that snow cover was shortened by 18 to 35 days due to dust radiative forcing in snow in the San Juan Mountains, Colorado, USA. This dust largely originates from the Colorado Plateau with increases of 5-7 fold in the last century and a half due to grazing and agricultural practices. For this study, we employ NCAR's WRF ARW v3.3+ model, which is coupled with a land surface model, Simplified Simple Biosphere version 3 (SSiB3). We first investigate the impact of different atmospheric radiative transfer schemes in WRF3.3+-SSiB3 on the regional climate downscaling. After conducting simulations over North America for the period March through June, we found substantial differences in the downscaling skills with different atmospheric radiative schemes. These differences indicate the uncertainty due to the atmospheric radiative transfer parameterizations. To develop a regional climate model that is capable of realistically simulating radiative forcing on snow covered areas with aerosol loading, we coupled WRF3.3+-SSiB3 with a snow-radiative transfer model, Snow, Ice, and Aerosol Radiative (SNICAR) model. SNICAR considers the effects of snow grain size and aerosol on snow albedo evolution. Snow grain size and growth is important in snow albedo feedbacks, especially when aerosols in snow are considered, because larger snow grains decrease snow albedo, and in the presence of dust, grain growth rates increase, decreasing snow reflectance even further than if the snow was pure. Our previous version of WRF3.3+-SSi

  11. A Method for Computing Leading-Edge Loads

    NASA Technical Reports Server (NTRS)

    Rhode, Richard V; Pearson, Henry A

    1933-01-01

    In this report a formula is developed that enables the determination of the proper design load for the portion of the wing forward of the front spar. The formula is inherently rational in concept, as it takes into account the most important variables that affect the leading-edge load, although theoretical rigor has been sacrificed for simplicity and ease of application. Some empirical corrections, based on pressure distribution measurements on the PW-9 and M-3 airplanes have been introduced to provide properly for biplanes. Results from the formula check experimental values in a variety of cases with good accuracy in the critical loading conditions. The use of the method for design purposes is therefore felt to be justified and is recommended.

  12. Recovery of Zinc and Lead from Electric-Furnace Steelmaking Dust at Berzelius

    NASA Astrophysics Data System (ADS)

    Maczek, Helmut; Kola, Rolf

    1980-01-01

    The Waelz unit at the Berzelius Metallhütten GmbH plant in Duisburg, West Germany, was originally built to recover zinc and lead values in zinc retort residues and slags from lead shaft furnaces. The process has also proved suitable for recovering zinc and lead from steelmaking dusts. The metallurgical characteristics and information on operating costs encountered in the three decades over which this Waelz plant has been in operation at Berzelius are described and discussed.

  13. Tracing dust transport from Middle-East over Delhi in March 2012 using metal and lead isotope composition

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Aggarwal, S. G.; Malherbe, J.; Barre, J. P. G.; Berail, S.; Gupta, P. K.; Donard, O. F. X.

    2016-05-01

    A severe dust-storm which was originated in Middle-East crossed over Delhi during March 20-22, 2012. We have collected these dust-storm (DS) aerosol samples, and analyzed them for selected metals (As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Se, Sn, Sr, V and Zn) together with after dust-storm (ADS) and winter (WS) samples. High aerosol mass loadings were observed in DS samples (1097-1965 μg/m3). On the contrary, metals derived prominently from the anthropogenic sources were found lower in concentration compared to that of ADS and WS aerosols. We observed significantly high concentrations of Ni and V (which are abundantly found in crude oils of Middle-East origin) in the DS samples than that of ADS and WS samples. Also enrichment factor (EF) of these metals with respect to Fe shows no significant enrichment (<10). Fe (and Sr) concentrations were also 3-5 fold higher in DS samples compared to ADS and WS. These results suggest that Ni and V can be used as tracers for dust aerosols transported from Middle-East region. Lead isotope signatures can tell about the variation in the sources of urban aerosols. Therefore Pb isotope analyses of these samples were performed using MC-ICP-MS. The isotope ratios, 208Pb/206Pb is determined to be (mean ± sd) 2.1315 ± 0.0018, 2.1370 ± 0.0022 and 2.1389 ± 0.0016, whereas 206Pb/207Pb is 1.1311 ± 0.0022, 1.1244 ± 0.0017 and 1.1233 ± 0.0016 in DS, ADS and WS aerosols, respectively. There is a clear distinction in Pb isotope composition between DS and urban (ADS and WS) aerosols. Further, these results suggest that in urban aerosols, Pb is less radiogenic in nature compared to that of in transported dust aerosols collected in New Delhi.

  14. Numerical Model for Conduction-Cooled Current Lead Heat Loads

    SciTech Connect

    White, M.J.; Wang, X.L.; Brueck, H.D.; /DESY

    2011-06-10

    Current leads are utilized to deliver electrical power from a room temperature junction mounted on the vacuum vessel to a superconducting magnet located within the vacuum space of a cryostat. There are many types of current leads used at laboratories throughout the world; however, conduction-cooled current leads are often chosen for their simplicity and reliability. Conduction-cooled leads have the advantage of using common materials, have no superconducting/normal state transition, and have no boil-off vapor to collect. This paper presents a numerical model for conduction-cooled current lead heat loads. This model takes into account varying material and fluid thermal properties, varying thicknesses along the length of the lead, heat transfer in the circumferential and longitudinal directions, electrical power dissipation, and the effect of thermal intercepts. The model is validated by comparing the numerical model results to ideal cases where analytical equations are valid. In addition, the XFEL (X-Ray Free Electron Laser) prototype current leads are modeled and compared to the experimental results from testing at DESY's XFEL Magnet Test Stand (XMTS) and Cryomodule Test Bench (CMTB).

  15. [Distribution characteristic and bioaccessibility of lead in kindergarten dust of Wuhan City].

    PubMed

    Sun, Guang-Yi; Bi, Xiang-Yang; Li, Zhong-Gen; Chen, Yu-Peng

    2011-11-01

    The characteristics of lead pollution and the associated health risk of children for the dust samples from 69 representative kindergartens in different type districts of Wuhan were investigated. Total lead concentration and bioaccessibility according to physiologically based extraction test (PBET) were determined. Results showed that the levels of lead concentration in dust ranged from 36.3 to 1 523 mg x kg(-1) with an average value of 169 mg x kg(-1), lower than published data from other areas. The great spatial variation of Pb in dust indicated that specific sites have been seriously contaminated by Pb. The bioaccessibilities of Pb in dusts were 35% +/- 15% at gastric phases and 7.6% +/- 5.8% at intestinal phases. According to the predicted model with the Integration Exposure Uptake Biokinetic Model (IEUBK), the geometric mean blood lead of children (0-6 years) was 2.73 microg x dL(-1), of which over 10 microg x dL(-1) was less than 0.001% and exceeded 5 microg x dL(-1) was 3.32%. PMID:22295628

  16. The bioaccessibility of lead (Pb) from vacuumed house dust on carpets in urban residences.

    PubMed

    Yu, Chang Ho; Yiin, Lih-Ming; Lioy, Paul J

    2006-02-01

    Risk assessments for toxicants in environmental media via oral exposure often rely on measurements of total concentration in a collected sample. However, the human digestive system cannot dissolute all of a toxicant present in the binding matrix, and cannot absorb it with nearly 100% efficiency. In vitro bioaccessibility has been developed as a method to estimate oral bioavailability of a toxicant using a physiologically-based extraction procedure. Bioaccessibility measurements are more physiologically relevant than strong acid leaching measurements of concentration. A method for measuring bioaccessible lead in house dust was derived from the bioaccessibility method currently used for heavy metals in contaminated soils. House dust was collected from carpets in typical urban residences. Bioaccessible lead was measured in house dust (<75 microm) from the homes of 15 participants. The bioaccessibility ranged from 52.4% to 77.2% in gastric fluid, and 4.9% to 32.1% in intestinal fluid. House dust samples from five homes were analyzed to assess the relationship among lead bioaccessibility of three particle size fractions (<75, 75-150, and 150-250 microm). Changes in lead bioaccessibility as a function of particle size fraction were not significant for gastric fluid (p= 0.7019); however they were significant for intestinal fluid (p= 0.0067). This decrease of bioaccessibility may result from the readsorption of dissolved lead onto the dust particles or precipitation of lead with phosphates in a high-pH environment. The bioaccessibility data obtained for two biofluids were applied to the IEUBK model, and results for intestinal bioaccessibility of lead provide support for the model default value of 30% lead bioavailability of dust as a reasonable population indicator for dose, but the higher values for gastric bioaccessibility of lead appeared to provide an upper bound that approached actual blood lead levels in the children living in the studied homes. This upper bound

  17. Mineral dust transport to the Sierra Nevada, California: Loading rates and potential source areas

    NASA Astrophysics Data System (ADS)

    Vicars, William C.; Sickman, James O.

    2011-03-01

    The transport and deposition of aeolian dust represents an important material input pathway for many marine and terrestrial ecosystems and may be an ecologically significant source of exogenous phosphorus (P) to alpine lakes. In order to assess the abundance and elemental composition of atmospheric mineral dust over the Sierra Nevada of California, we collected size-fractionated atmospheric particulate matter (PM) samples during July 2008 to March 2009 at a mixed conifer site located in Sequoia National Park. PM concentrations were at their highest levels during the dry season, averaging 8.8 ± 3.7 and 11.1 ± 7.5 μg m-3 for the coarse (1 μm < Da < 15 μm) and fine (Da < 1 μm) fractions, respectively, while winter months were characterized by low (<1 μg m-3) PM concentrations in both size fractions. Using Al as a diagnostic tracer for mineral aerosol, we observed a significant and uniform contribution (50-80%) from aeolian dust to the total coarse PM load, whereas submicron particles contained comparatively little crustal material (7-33%). The mass concentrations of elements (Fe, Ca, Mg, P, and V) in the coarse PM fraction were significantly correlated with Al throughout the study, and coarse PM exhibited elemental signatures that were temporally consistent and distinguishable from those of other sites. Conversely, higher elemental enrichments were observed in the fine PM fraction for Fe, V, and P, indicating a greater contribution from anthropogenic emissions to the fine particle load. Fe/Al and Fe/Ca ratios suggest a mixture of mineral dust from regional agricultural activities and long-range transport of mineral dust from Asia. Asian sources comprised 40-90% of mineral dust in July 2008 and then declined to between 10 and 30% in August and early September.

  18. Sensitivity of dust emissions to aerosol feedback and the impact of dust loading on climate forcing with varied resolutions using FIM-Chem

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Grell, Georg; Henze, Daven; Mckeen, Stuart; Sun, Shan; Li, Haiqin

    2016-04-01

    Meteorological conditions directly impact aerosol loading, especially dust emissions. Variations in dust emissions on the other hand, will also impact meteorology and climate through direct and indirect aerosol forcing. To study these impacts in more detail we use the global Flow-following finite-volume Icosahedra Model (FIM, http://fim.noaa.gov/), a new global weather prediction model currently under development in the Global Systems Division of NOAA/ESRL, as it is coupled online with the aerosol modules from the Goddard Gobal Ozone Chemistry Aerosol Radiation and Transport (GOCART) model (FIM-Chem). FIM-Chem includes direct and semi direct feedback, and uses the dust schemes of GOCART and the Air Force Weather Agency (AFWA). FIM-Chem is able to investigate the contribution of climate feedbacks to simulated hyperspectral data by considering a range of simulations with different dust emissions and different levels of aerosol feedbacks enabled at four different spatial resolutions. The emitted dust flux and total emissions are highly depending on the wind, soil moisture and model resolution. We compare the dust emissions by including and excluding the aerosol radiative feedback in the simulations to quantify the sensitivity of dust emissions to aerosol feedback. The results show that all aerosol-induced dust emissions increase about 10% globally, which is mainly dominated by the contributions of anthropogenic black carbon (EC) aerosol. While the dust-induced percentage changes of dust emissions are about -5.5%, that indicates reduction effect globally. Also, the simulations based on different resolutions of 240x240 km, 120x120 km, 60x60 km and 30x30 km are performed to test the impacts of model resolution on total dust emissions. By comparing the dust emission sensitivity to aerosol feedback and model resolution, we can estimate the uncertainty of model resolution versus aerosol feedback. We also conduct FIM-Chem simulations to investigate the sensitivity of dust

  19. Mobilization and distribution of lead originating from roof dust and wet deposition in a roof runoff system.

    PubMed

    Yu, Jianghua; Yu, Haixia; Huang, Xiaogu

    2015-12-01

    In this research, the mobilization and distribution of lead originating in roof dust and wet deposition were investigated within a roof dust-rooftop-runoff system. The results indicated that lead from roof dust and wet deposition showed different transport dynamics in runoff system and that this process was significantly influenced by the rainfall intensity. Lead present in the roof dust could be easily washed off into the runoff, and nearly 60 % of the total lead content was present in particulate form. Most of the lead from the roof dust was transported during the late period of rainfall; however, the lead concentration was higher for several minutes at the rainfall beginning. Even though some of the lead from wet deposition, simulated with a standard isotope substance, was adsorbed onto adhered roof dust and/or retained on rooftop in runoff system, most of it (50-82 %) remained as dissolved lead in the runoff for rainfall events of varying intensity. Regarding the distribution of lead in the runoff system, the results indicated that it could be carried in the runoff in dissolved and particulate form, be adsorbed to adhered roof dust, or remain on the rooftop because of adsorption to the roof material. Lead from the different sources showed different distribution patterns that were also related to the rainfall intensity. Higher rainfall intensity resulted in a higher proportion of lead in the runoff and a lower proportion of lead remaining on the rooftop. PMID:26289339

  20. What caused terrestrial dust loading and climate downturns between 533 and 540 A.D.?

    NASA Astrophysics Data System (ADS)

    Abbott, D. H.; Breger, D. L.; Biscaye, P. E.; Barron, J. A.; Juhl, R. A.; McCafferty, P.

    2013-12-01

    Sn-rich particles, Ni-rich particles and cosmic spherules are found together at four stratigraphic levels in the GISP2 ice core between 360 and 362 meters depth. Using a previously derived calendar-year time scale, these particles span a time of increased dust loading of the Earth's atmosphere between 533 and 540 A.D. The Sn enrichments suggest a cometary source for the dust. The late spring timing of extraterrestrial input best matches the Eta Aquarid meteor shower associated with comet 1P/Halley. The increased flux of cometary dust could explain a modest climate downturn in 533 A.D. The profound global dimming during 536 and 537 A.D. cannot be explained merely by a combination of cometary dust and a modest volcanic eruption. We found tropical marine microfossils at the end 535-start 536 A.D. level that we attribute to a low-latitude explosion in the ocean. This additional source of dust is probably needed to explain the solar dimming in 536-537 A.D. In addition, we found high-latitude marine diatoms and silicoflagellates at a second time horizon, circa 538 A.D. Some of the fossils are pre-Pleistocene in age, as old as Eocene. Both of these fossil-bearing stratigraphic levels contain enrichments of nitrate and ammonium in their supernatant water.

  1. Origin and patterns of distribution of trace elements in street dust: Unleaded petrol and urban lead

    NASA Astrophysics Data System (ADS)

    Miguel, Eduardo de; Llamas, Juan F.; Chacón, Enrique; Berg, Torunn; Larssen, Steinar; Røyset, Oddvar; Vadset, Marit

    The elemental composition, patterns of distribution and possible sources of street dust are not common to all urban environments, but vary according to the peculiarities of each city. The common features and dissimilarities in the origin and nature of street dust were investigated through a series of studies in two widely different cities, Madrid (Spain) and Oslo (Norway), between 1990 and 1994. The most comprehensive sampling campaign was carried out in the Norwegian capital during the summer of 1994. An area of 14 km 2, covering most of downtown Oslo and some residential districts to the north of the city, was divided into 1 km2 mapping units, and 16 sampling increments of approximately 150 g were collected from streets and roads in each of them. The fraction below 100 μm was acid-digested and analysed by ICP-MS. Statistical analyses of the results suggest that chemical elements in street dust can be classified into three groups: "urban" elements (Ba, Cd, Co, Cu, Mg, Pb, Sb, Ti, Zn), "natural" elements (Al, Ga, La, Mn, Na, Sr, Th, Y) and elements of a mixed origin or which have undergone geochemical changes from their original sources (Ca, Cs, Fe, Mo, Ni, Rb, Sr, U). Soil resuspension and/or mobilisation appears to be the most important source of "natural" elements, while "urban" elements originate primarily from traffic and from the weathering and corrosion of building materials. The data for Pb seem to prove that the gradual shift from leaded to unleaded petrol as fuel for automobiles has resulted in an almost proportional reduction in the concentration of Pb in dust particles under 100 μm. This fact and the spatial distribution of Pb in the city strongly suggest that lead sources other than traffic (i.e. lead accumulated in urban soil over the years) may contribute as much lead, if not more, to urban street dust.

  2. Depression of alveolar macrophage hydrogen peroxide and superoxide anion release by mineral dusts: Correlation with antimony, lead, and arsenic contents

    SciTech Connect

    Gulyas, H.; Labedzka, M.; Gercken, G. )

    1990-04-01

    Activated rabbit alveolar macrophages were incubated with airborne dusts from four West German sites (1 to 200 micrograms/10(6) cells) and waste incinerator fly ash fractions (50 to 500 micrograms/10(6) cells). Quartz dust DQ 12 (5 to 200 micrograms/10(6) cells) and Fe2O3 (0.05 to 50 micrograms/10(6) cells) were used as control dusts. The zymosan-stimulated hydrogen peroxide and superoxide anion release of the macrophages were not affected significantly by Fe2O3. All other investigated dusts decreased the two cell functions which were correlated negatively with surfaces, particle numbers, and antimony, lead, and arsenic contents of the dusts. The influence of heavy metal antagonisms and dust surfaces on dust toxicity against alveolar macrophages is discussed.

  3. Depression of alveolar macrophage hydrogen peroxide and superoxide anion release by mineral dusts: correlation with antimony, lead, and arsenic contents.

    PubMed

    Gulyas, H; Labedzka, M; Gercken, G

    1990-04-01

    Activated rabbit alveolar macrophages were incubated with airborne dusts from four West German sites (1 to 200 micrograms/10(6) cells) and waste incinerator fly ash fractions (50 to 500 micrograms/10(6) cells). Quartz dust DQ 12 (5 to 200 micrograms/10(6) cells) and Fe2O3 (0.05 to 50 micrograms/10(6) cells) were used as control dusts. The zymosan-stimulated hydrogen peroxide and superoxide anion release of the macrophages were not affected significantly by Fe2O3. All other investigated dusts decreased the two cell functions which were correlated negatively with surfaces, particle numbers, and antimony, lead, and arsenic contents of the dusts. The influence of heavy metal antagonisms and dust surfaces on dust toxicity against alveolar macrophages is discussed. PMID:2159400

  4. Using Engineering Cameras on Mars Landers and Rovers to Retrieve Atmospheric Dust Loading

    NASA Astrophysics Data System (ADS)

    Wolfe, C. A.; Lemmon, M. T.

    2014-12-01

    Dust in the Martian atmosphere influences energy deposition, dynamics, and the viability of solar powered exploration vehicles. The Viking, Pathfinder, Spirit, Opportunity, Phoenix, and Curiosity landers and rovers each included the ability to image the Sun with a science camera that included a neutral density filter. Direct images of the Sun provide the ability to measure extinction by dust and ice in the atmosphere. These observations have been used to characterize dust storms, to provide ground truth sites for orbiter-based global measurements of dust loading, and to help monitor solar panel performance. In the cost-constrained environment of Mars exploration, future missions may omit such cameras, as the solar-powered InSight mission has. We seek to provide a robust capability of determining atmospheric opacity from sky images taken with cameras that have not been designed for solar imaging, such as lander and rover engineering cameras. Operational use requires the ability to retrieve optical depth on a timescale useful to mission planning, and with an accuracy and precision sufficient to support both mission planning and validating orbital measurements. We will present a simulation-based assessment of imaging strategies and their error budgets, as well as a validation based on archival engineering camera data.

  5. Retrieving Atmospheric Dust Loading on Mars Using Engineering Cameras and MSL's Mars Hand Lens Imager (MAHLI)

    NASA Astrophysics Data System (ADS)

    Wolfe, C. A.; Lemmon, M. T.

    2015-12-01

    Dust in the Martian atmosphere influences energy deposition, dynamics, and the viability of solar powered exploration vehicles. The Viking, Pathfinder, Spirit, Opportunity, Phoenix, and Curiosity landers and rovers each included the ability to image the Sun with a science camera equipped with a neutral density filter. Direct images of the Sun not only provide the ability to measure extinction by dust and ice in the atmosphere, but also provide a variety of constraints on the Martian dust and water cycles. These observations have been used to characterize dust storms, to provide ground truth sites for orbiter-based global measurements of dust loading, and to help monitor solar panel performance. In the cost-constrained environment of Mars exploration, future missions may omit such cameras, as the solar-powered InSight mission has. We seek to provide a robust capability of determining atmospheric opacity from sky images taken with cameras that have not been designed for solar imaging, such as the engineering cameras onboard Opportunity and the Mars Hand Lens Imager (MAHLI) on Curiosity. Our investigation focuses primarily on the accuracy of a method that determines optical depth values using scattering models that implement the ratio of sky radiance measurements at different elevation angles, but at the same scattering angle. Operational use requires the ability to retrieve optical depth on a timescale useful to mission planning, and with an accuracy and precision sufficient to support both mission planning and validating orbital measurements. We will present a simulation-based assessment of imaging strategies and their error budgets, as well as a validation based on the comparison of direct extinction measurements from archival Navcam, Hazcam, and MAHLI camera data.

  6. Effect of dust load on the leaf attributes of the tree species growing along the roadside.

    PubMed

    Chaturvedi, R K; Prasad, Shikha; Rana, Savita; Obaidullah, S M; Pandey, Vijay; Singh, Hema

    2013-01-01

    Dust is considered as one of the most widespread air pollutants. The objective of the study was to analyse the effect of dust load (DL) on the leaf attributes of the four tree species planted along the roadside at a low pollution Banaras Hindu University (BHU) campus and a highly polluted industrial area (Chunar, Mirzapur) of India. The studied leaf attributes were: leaf area, specific leaf area (SLA), relative water content (RWC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), chlorophyll content (Chl), maximum stomatal conductance (Gs(max)), maximum photosynthetic rate (A (max)) and intrinsic water-use efficiency (WUEi). Results showed significant effect of sites and species for DL and the leaf attributes. Average DL across the four tree species was greater at Chunar, whereas, the average values of leaf attributes were greater at the BHU campus. Maximum DL was observed for Tectona grandis at Chunar site and minimum for Syzygium cumini at BHU campus. Across the two sites, maximum value of SLA, Chl and Gs(max) were exhibited by S. cumini, whereas, the greatest value of RWC, LNC, LPC, A (max) and WUEi were observed in Anthocephalus cadamba. A. cadamba and S. cumini exhibited 28 and 27 times more dust accumulation, respectively, at the most polluted Chunar site as compared to the BHU campus. They also exhibited less reduction in A (max) due to dust deposition as compared to the other two species. Therefore, both these species may be promoted for plantation along the roadside of the sites having greater dust deposition. PMID:22367367

  7. Tracing dust transport from Middle-East over Delhi in March 2012 using metal and lead isotope composition

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Aggarwal, S. G.; Malherbe, J.; Barre, J. P. G.; Berail, S.; Gupta, P. K.; Donard, O. F. X.

    2016-05-01

    A severe dust-storm which was originated in Middle-East crossed over Delhi during March 20-22, 2012. We have collected these dust-storm (DS) aerosol samples, and analyzed them for selected metals (As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Se, Sn, Sr, V and Zn) together with after dust-storm (ADS) and winter (WS) samples. High aerosol mass loadings were observed in DS samples (1097-1965 μg/m3). On the contrary, metals derived prominently from the anthropogenic sources were found lower in concentration compared to that of ADS and WS aerosols. We observed significantly high concentrations of Ni and V (which are abundantly found in crude oils of Middle-East origin) in the DS samples than that of ADS and WS samples. Also enrichment factor (EF) of these metals with respect to Fe shows no significant enrichment (<10). Fe (and Sr) concentrations were also 3-5 fold higher in DS samples compared to ADS and WS. These results suggest that Ni and V can be used as tracers for dust aerosols transported from Middle-East region. Lead isotope signatures can tell about the variation in the sources of urban aerosols. Therefore Pb isotope analyses of these samples were performed using MC-ICP-MS. The isotope ratios, 208Pb/206Pb is determined to be (mean ± sd) 2.1315 ± 0.0018, 2.1370 ± 0.0022 and 2.1389 ± 0.0016, whereas 206Pb/207Pb is 1.1311 ± 0.0022, 1.1244 ± 0.0017 and 1.1233 ± 0.0016 in DS, ADS and WS aerosols, respectively. There is a clear distinction in Pb isotope composition between DS and urban (ADS and WS) aerosols. Further, these results suggest that in urban aerosols, Pb is less radiogenic in nature compared to that of in transported dust aerosols collected in New Delhi.

  8. Relative Contributions of the Saharan and Sahelian Sources to the Atmospheric Dust Load Over the North Atlantic

    NASA Technical Reports Server (NTRS)

    Ginoux, Paul; Chin, M.; Torres, O.; Prospero, J.; Dubovik, O.; Holben, B.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    It has long been recognized that Saharan desert is the major source for long range transport of mineral dust over the Atlantic. The contribution from other natural sources to the dust load over the Atlantic has generally been ignored in previous model studies or been replaced by anthropogenically disturbed soil emissions. Recently, Prospero et.at. have identified the major dust sources over the Earth using TOMS aerosol index. They showed that these sources correspond to dry lakes with layers of sediment deposed in the late Holocene or Pleistocene. One of the most active of these sources seem to be the Bodele depression. Chiapello et al. have analyzed the mineralogical composition of dust on the West coast of Africa. They found that Sahelian dust events are the most intense but are less frequent than Saharan plumes. This suggests that the Bodele depression could contribute significantly to the dust load over the Atlantic. The relative contribution of the Sahel and Sahara dust sources is of importance for marine biogeochemistry or atmospheric radiation, because each source has a distinct mineralogical composition. We present here a model study of the relative contributions of Sahara and Sahel sources to the atmospheric dust aerosols over the North Atlantic. The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate dust distribution in 1996-1997. Dust particles are labeled depending on their sources. In this presentation, we will present the comparison between the model results and observations from ground based measurements (dust concentration, optical thickness and size distribution) and satellite data (TOMS aerosol index). The relative contribution of each source will then be analyzed spatially and temporally.

  9. Cycling of Lead Through Soil, Air, and Household Dust in El Paso, Texas

    NASA Astrophysics Data System (ADS)

    Pingitore, N. E.; Clague, J.; Amaya, M. A.

    2008-12-01

    Elimination of leaded gasoline in the US is associated with a dramatic overall decrease in ambient lead in the environment and blood lead levels in our population. However, Pb is such a potent neurotoxin for children during the formative growth years that legislation for additional reduction of airborne lead levels is under consideration. X-ray absorption spectroscopy of a suite of samples of local (El Paso) soil, airborne particulate matter, and household dust reveals that lead humate is the dominant Pb species in these diverse environmental materials. Lead humate is a stable complex of Pb with the humus component of soil, a product of interaction between the humus and such introduced contaminant lead species as lead oxide, lead sulfate, etc. Because lead humate forms only in soil, we conclude that the source of the majority of the lead in El Paso's airborne particulate matter and household dust is local soils. Analysis of lead isotopes in selected samples is consistent with this conclusion. Re-entrainment of low-density (relative to most Pb species) humus soil particles is the apparent pathway from soil to air. Deposition of airborne particulate matter and pedal traction are the presumed mechanisms for transfer to household interiors. Reduction of airborne lead in El Paso by reducing input from its dominant local source may require extensive soil remediation, a tedious and expensive prospect. X-Ray absorption spectroscopy experiments were conducted at the Stanford Synchrotron Radiation Laboratory on beam lines 7-3, 10-2, and 11-2. Spectra were collected at the Pb L-III absorption edge in fluorescence mode using a 13-element or a 30-element Ge solid-state detector. This publication was made possible by grant numbers 1RO1-ES11367 and 1 S11 ES013339-04 from the National Institute of Environmental Health Sciences (NIEHS), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH. Partial

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

    PubMed

    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 <0.001 to 2.9mg/m(3), and, in all but one case, resulted in concentrations below the current U.S. Occupational Safety and Health Administration's Permissible Exposure Limits and the American Conference of Governmental Industrial Hygienists' Threshold Limit Values. The arithmetic mean total dust concentration resulting from long-term personal samples was 0.31mg/m(3). The data presented here are the most complete set of its kind in the open literature, and are useful for understanding the potential exposures during solid catalyst handling activities at this petroleum refinery and perhaps other modern refineries during the timeframe examined. PMID:22177528

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

    USGS Publications Warehouse

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

    2016-01-01

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

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

    SciTech Connect

    Taylor, Mark Patrick 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.

  13. Lead Speciation in Indoor Dust: A Case Study to Assess Old Paint Contribution in a Canadian Urban House

    SciTech Connect

    S Beauchemin; L MacLean; P Rasmussen

    2011-12-31

    Residents in older homes may experience increased lead (Pb) exposures due to release of lead from interior paints manufactured in past decades, especially pre-1960s. The objective of the study was to determine the speciation of Pb in settled dust from an urban home built during WWII. X-ray absorption near-edge structure (XANES) and micro-X-ray diffraction (XRD) analyses were performed on samples of paint (380-2,920 mg Pb kg{sup -1}) and dust (200-1,000 mg Pb kg{sup -1}) collected prior to renovation. All dust samples exhibited a Pb XANES signature similar to that of Pb found in paint. Bulk XANES and micro-XRD identified Pb species commonly found as white paint pigments (Pb oxide, Pb sulfate, and Pb carbonate) as well as rutile, a titanium-based pigment, in the <150 m house dust samples. In the dust fraction <36 {mu}m, half of the Pb was associated with the Fe-oxyhydroxides, suggesting additional contribution of outdoor sources to Pb in the finer dust. These results confirm that old paints still contribute to Pb in the settled dust for this 65-year-old home. The Pb speciation also provided a clearer understanding of the Pb bioaccessibility: Pb carbonate > Pb oxide > Pb sulfate. This study underscores the importance of taking precautions to minimize exposures to Pb in house dust, especially in homes where old paint is exposed due to renovations or deterioration of painted surfaces.

  14. Lead speciation in indoor dust: a case study to assess old paint contribution in a Canadian urban house

    SciTech Connect

    Beauchemin, Suzanne; MacLean, Lachlan C.W.; Rasmussen, Pat E.

    2012-10-23

    Residents in older homes may experience increased lead (Pb) exposures due to release of lead from interior paints manufactured in past decades, especially pre-1960s. The objective of the study was to determine the speciation of Pb in settled dust from an urban home built during WWII. X-ray absorption near-edge structure (XANES) and micro-X-ray diffraction (XRD) analyses were performed on samples of paint (380-2,920 mg Pb kg{sup -1}) and dust (200-1,000 mg Pb kg{sup -1}) collected prior to renovation. All dust samples exhibited a Pb XANES signature similar to that of Pb found in paint. Bulk XANES and micro-XRD identified Pb species commonly found as white paint pigments (Pb oxide, Pb sulfate, and Pb carbonate) as well as rutile, a titanium-based pigment, in the <150 {micro}m house dust samples. In the dust fraction <36 {micro}m, half of the Pb was associated with the Fe-oxyhydroxides, suggesting additional contribution of outdoor sources to Pb in the finer dust. These results confirm that old paints still contribute to Pb in the settled dust for this 65-year-old home. The Pb speciation also provided a clearer understanding of the Pb bioaccessibility: Pb carbonate > Pb oxide > Pb sulfate. This study underscores the importance of taking precautions to minimize exposures to Pb in house dust, especially in homes where old paint is exposed due to renovations or deterioration of painted surfaces.

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

    NASA Astrophysics Data System (ADS)

    Felix Villar, Omar I.

    Mining activities generate aerosol in a wide range of sizes. Smelting activities produce mainly fine particles (<1 microm). On the other hand, milling, crushing and refining processes, as well tailings management, are significant sources of coarse particles (> 1 microm). The adverse effects of aerosols on human health depend mainly on two key characteristics: size and chemical composition. One of the main objectives of this research is to analyze the size distribution of contaminants in aerosol produced by mining operations. For this purpose, a Micro-Orifice Uniform Deposit Impactor (MOUDI) was utilized. Results from the MOUDI samples show higher concentrations of the toxic elements like lead and arsenic in the fine fraction (<1 microm). Fine particles are more likely to be deposited in the deeper zones of the respiratory system; therefore, they are more dangerous than coarse particles that can be filtered out in the upper respiratory system. Unfortunately, knowing the total concentration of contaminants does not give us enough information to identify the source of contamination. For this reason, lead isotopes have been introduced as fingerprints for source apportionment. Each source of lead has specific isotopic ratios; by knowing these ratios sources can be identified. During this research, lead isotopic ratios were analyzed at different sites and for different aerosol sizes. From these analyses it can be concluded that lead isotopes are a powerful tool to identify sources of lead. Mitigation strategies could be developed if the source of contamination is well defined. Environmental conditions as wind speed, wind direction, relative humidity and precipitation have an important role in the concentration of atmospheric dust. Dry environments with low relative humidity are ideal for the transport of aerosols. Results obtained from this research show the relationship between dust concentrations and meteorological parameters. Dust concentrations are highly correlated

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

    PubMed

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

    2014-11-01

    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. PMID:25462679

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

    PubMed

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

    2014-06-01

    The levels of 25 elements in house dust collected from 100 general Japanese residences were measured. Factor analysis was applied on the multi-element data to explore source of Pb (median concentration 49.1 mg/kg) in house dust. Six factors were extracted and Pb was found to have great loading on the fifth factor with Sb and Sn, suggesting solder (Sn), and plastic and metals (Sb) may be the sources of Pb in the house dust of Japanese residences. No significant loading was found on soil-related factors indicating non-significant contribution of Pb in track-in soil. Seven heavy metals (Cd, Cu, Mo, Pb, Sb, Sn, and Zn) were found in house dust at >10 times more condensed than crustal abundance. Health risk of these elements to children via the ingestion of house dust was estimated based on the comparison with tolerable daily intake and found to be non-significant for most of the elements. PMID:24682073

  18. Atmospheric dust loads and their elemental composition at a background site in India.

    PubMed

    Negi, B S; Jha, S K; Chavan, S B; Sadasivan, S; Goyal, A; Sapru, M L; Bhat, C L

    2002-01-01

    Air particulate samples collected during 1995-96 at a background site situated on the east coast of Thar Desert in Rajsthan State of India were analysed for atmospheric dust loads (Suspended Particulate Matter) and elemental composition. The values of SPM ranged from 9 microg M(-3) to 97 microg M(-3) with an average of 43 microg M(-3) except a few episodic values, which were 3 to 5 times higher than the average during summer months. The results for elemental composition of the particulate samples showed that the concentrations of anthropogenic toxic trace elements viz. Br, Cr, Pb, Sb, Se and Zn are lower by a factor of 2 to 10 as compared to urban areas. The high enrichment factors for anthropogenic elements viz. Br, Pb, Sb and Zn show an input from coal/wood fuel burning and vehicular pollution at the sampling site. The depletion of Si in SPM samples shows long distance transport of dust to the sampling site. PMID:11878626

  19. The impact of drinking water, indoor dust and paint on blood lead levels of children aged 1–5 years in Montréal (Québec, Canada)

    PubMed Central

    Levallois, Patrick; St-Laurent, Julie; Gauvin, Denis; Courteau, Marilène; Prévost, Michèle; Campagna, Céline; Lemieux, France; Nour, Shokoufeh; D'Amour, Monique; Rasmussen, Pat E

    2014-01-01

    Lead is neurotoxic at very low dose and there is a need to better characterize the impact of domestic sources of lead on the biological exposure of young children. A cross-sectional survey evaluated the contribution of drinking water, house dust and paint to blood lead levels (BLLs) of young children living in old boroughs of Montréal (Canada). Three hundred and six children aged 1 to 5 years and currently drinking tap water participated in the study. For each participant, residential lead was measured in kitchen tap water, floor dust, windowsill dust and house paint and a venous blood sample was analyzed. Multivariate logistic regression was used to evaluate the association between elevated BLL in the children (≥ 75th percentile) and indoor lead contamination by means of odds ratios (OR) using 95% confidence intervals (CI). There was an association between BLL ≥75th percentile (1.78 μg/dL) and water lead when the mean water concentration was >3.3 μg/L: adjusted OR=4.7 (95% CI: 2.1–10.2). Windowsill dust loading >14.1 μg/ft2 was also associated with BLL ≥1.78 μg/dL: adjusted OR=3.2 (95% CI: 1.3–7.8). Despite relatively low BLLs, tap water and house dust lead contribute to an increase of BLLs in exposed young children. PMID:23361441

  20. Evaluation of Ag nanoparticle coated air filter against aerosolized virus: Anti-viral efficiency with dust loading.

    PubMed

    Joe, Yun Haeng; Park, Dae Hoon; Hwang, Jungho

    2016-01-15

    In this study, the effect of dust loading on the anti-viral ability of an anti-viral air filter was investigated. Silver nanoparticles approximately 11 nm in diameter were synthesized via a spark discharge generation system and were used as anti-viral agents coated onto a medium air filter. The pressure drop, filtration efficiency, and anti-viral ability of the filter against aerosolized bacteriophage MS2 virus particles were tested with dust loading. The filtration efficiency and pressure drop increased with dust loading, while the anti-viral ability decreased. Theoretical analysis of anti-viral ability with dust loading was carried out using a mathematical model based on that presented by Joe et al. (J. Hazard. Mater.; 280: 356-363, 2014). Our model can be used to compare anti-viral abilities of various anti-viral agents, determine appropriate coating areal density of anti-viral agent on a filter, and predict the life cycle of an anti-viral filter. PMID:26434534

  1. Occurrence, speciation and bioaccessibility of lead in Chinese rural household dust and the associated health risk to children

    NASA Astrophysics Data System (ADS)

    Han, Zhixuan; Bi, Xiangyang; Li, Zhonggen; Yang, Wenlin; Wang, Lixing; Yang, Huan; Li, Fanglin; Ma, Zhendong

    2012-01-01

    Lead (Pb) concentration, speciation and bioaccessibility were measured in 122 household dust samples collected in rural areas of eight provinces of China. The mean Pb concentration in the household dust was 208 mg kg -1, of which samples from sites in Hunan (538 mg kg -1) and Yunnan (280 mg kg -1) provinces exhibited the highest Pb concentrations while those from Shaanxi (96 mg kg -1) and Fujian (80 mg kg -1) provinces had a relatively low Pb content. The major fraction of Pb in the household dust samples was found to be strongly bound to Fe-Mn oxide phases (37%) while Pb present in minor fractions individually making up between 14 and 18% was characterized in falling orders as residual, carbonate, organic/sulphide, and exchangeable fractions by the sequential extraction method applied. Bioaccessible Pb making up an average proportion of 53% in the household dusts was significantly correlated to the Fe-Mn oxide phases of Pb. According to the Hazard Quotient (HQ), the ingestion of dust particles pose the highest risk to children in Chinese rural areas, followed by dermal contact and inhalation. Hazard Index (HI) values for most samples were lower than 1, indicating that the domestic Pb exposure in rural areas of China were relatively safe for children when they exposure to the household dust. However, dust Pb in 4.1% of the studied families having HI values higher than 1 may pose adverse health effect to the children.

  2. Garden soil and house dust as exposure media for lead uptake in the mining village of Stratoni, Greece.

    PubMed

    Argyraki, Ariadne

    2014-08-01

    The relationships between two exposure media, garden soil and house dust, were studied for Pb uptake in Stratoni village in northern Greece, an industrial area of mining and processing of sulphide ore. Lead data for the two media were assessed in terms of total and bioaccessible content, measurement and geochemical variability, and mineralogical composition. It was found that total Pb was enriched in house dust samples by a factor of 2 on average. Total Pb concentration in soil samples had a maximum of 2,040 mg/kg and reached a maximum of 7,000 mg/kg in house dust samples. The estimated variability due to measurement uncertainty was dominated by the sampling process, and the proportion of sampling variance was greater for soil samples, indicating a higher degree of Pb heterogeneity in soil on the given spatial scale of sampling strata. Although the same general spatial trend was observed for both sampling media with decreasing Pb concentration by increasing distance from the ore-processing plant, Pb in dust samples displayed the highest concentrations within a 300-600-m zone from the ore-processing facility. The significant differences which were observed in Pb speciation between the studied media were explained by differences in mineralogical composition of outdoor soil and indoor dust. Lead-enriched Fe and Mn oxides predominated in soil samples while fine galena grains (<10-20 μm diameter) were the major Pb-bearing phase in dust samples. The integrated exposure uptake biokinetic model was used to predict the risk of elevated blood lead levels in children of Stratoni. Model prediction indicated an average probability of 61 % for blood-Pb to exceed 10 μg/dl. The results underline the importance of house dust in risk assessment and highlight the effect of outdoor and indoor conditions on the fate of Pb in the particular environment of Stratoni. PMID:24292695

  3. Direct shear loading leads to failure of generator bolts, rotor

    SciTech Connect

    Flanagan, P.J.; Knittel, D. )

    1993-02-01

    Direct shear loading can result in the failure of bolts clamping the rotor flange to the shaft flange of a hydroelectric generator. Such was the case at the California Department of Water Resources 440-MW Gianelli Pumping-Generating Plant. The incident occurred July 5, 1991, when operators were bringing Unit 1 into service for generation. Tremendous forces on one of the unit's two rotors sheared ten 3 1/2-inch-diameter spider flange assembly bolts (ASTM A193-B16 steel) on the rotor, deforming bolt holes in both the spider flange and the shaft flange. The flanges, which allow the generator to transmit power through friction, rubbed and galled before the unit came to rest. The sudden shock load also slightly twisted the spider of the rotor, which during normal operation turns at 120 revolutions per minute at head of 190 to 245 feet. During normal operation, operators open a butterfly valve, allowing water to rush from a penstock to turn an impeller, which is connected to the generator rotor. Each of the plant's eight units is equipped with two rotors mounted on the same shaft. As the butterfly valve is gradually opened, speed of the unit increases. When the generator rotor is spinning at 90 percent of synchronous speed, the main unit breaker closes, energizing the stator windings with 13,800 volts. This rapidly accelerates the generator to approximately 98 percent of synchronous speed. The field breaker then closes, energizing the rotor poles with DC current. The rotor current reaches full strength in 2 to 5 seconds. During this time, the poles on the rotor are attempting to fall into step with the stator's rotating magnetic field.

  4. Experimental Comparison of Load-Strengthening and Load-Weakening Behaviour Leading to Fault Reshear

    NASA Astrophysics Data System (ADS)

    Mitchell, Tom; Sibson, Richard; Renner, Jörg

    2010-05-01

    In this study, we assess the loading of faults to failure under different stress regimes in a triaxial deformation apparatus, both in dry and saturated conditions. We explore experimentally the reshear of an existing fault at particular values of (?1 - ?3) and ?3' for contrasting loading systems - load-strengthening (equivalent to a thrust fault) with ?1' increasing at constant ?3', versus load-weakening (equivalent to a normal fault) with reducing ?3' under constant ?1'. Prefailure and postfailure behaviour is compared in terms of damage zone development via monitoring variations in ultrasonic velocity and acoustic emission behaviour. In addition, we explore reshear conditions under an initial condition of (?1' = ?3'), then inducing reshear on the existing fault first by increasing ?1' (load-strengthening), then by decreasing ?3' (load-weakening), again comparing relative damage zone development and acoustic emission levels. Experiments are conducted on sawcut granite samples with fault angles at a variety of orientations relative to ?1, ranging from an optimal orientation for reactivation to orientation for frictional lock-up.

  5. Cleaning of Dust between Interactive Contact Surfaces by Application of Normal Loads of Artificial Stainless-Cantilever in AFM

    NASA Astrophysics Data System (ADS)

    Choi, Seungchol; Horie, Mikio; Ando, Yasuhisa

    In this study, we investigated that interactive contact surfaces were affected by dust and applied normal loads of cantilever such as bristles. In order to study the effect of interactive contact surfaces, spherical particles (dry borosilicate glass sphere, plastic sphere) with curvature radius (R=5 μm, R=10 μm) were glued to artificial stainless cantilevers (spring constant k=576.7 N/m). The experiments were performed on various normal applied loads using an AFM (Atomic force microscope). The results indicate that spheres with a small curvature radius removed dust more effectively than did either of those with a large curvature radius, abraded by using the stainless cantilever, over the wide contact area (50 μmx50 μm). The plastic spheres tend to deform more than do the borosilicate glass spheres under the same applied load and the spheres with a smaller curvature radius tend to deform than do those with a larger curvature radius and the same material properties. Therefore, it had an influence on interactive surface forces. Restructuring dust aggregates by sliding a cantilever, as well as applying loads and contact pressure, forms a new micro contact area, which influences micro surface forces.

  6. Lead, arsenic, and polycyclic aromatic hydrocarbons in soil and house dust in the communities surrounding the Sydney, Nova Scotia, tar ponds.

    PubMed Central

    Lambert, Timothy W; Lane, Stephanie

    2004-01-01

    This study evaluated lead, arsenic, and polycyclic aromatic hydrocarbon (PAH) contamination in the residential communities adjacent to the Sydney, Nova Scotia, tar ponds, the area considered Canada's worst contaminated site. The tar pond remediation policy has been limited to the site and some residential properties. We compared background concentrations in 91 soil samples taken 5-20 km from the coke oven site with those in soil samples from the three communities surrounding the tar ponds: Whitney Pier, Ashby, and North End. These surrounding communities were statistically different from background regarding arsenic, lead, and PAHs. Twenty percent of the background soil samples and 95% of the tar pond soil samples were above the Canadian health-risk-based soil guidelines for arsenic (12 ppm), and 5% of the background samples and 80% of the tar pond soil samples were above the Canadian guidelines for lead (140 ppm). Regarding dust lead and arsenic loading, the results provide no evidence that Whitney Pier is significantly different than Ashby and North End. Children in these communities are predicted to have a 1-15% chance of blood lead > 10 microg/dL. The results suggest that lead and arsenic found in the homes originate outside. The lead content of paint in the homes was not evaluated, but consideration of painted wood at the doorway did not confound the results of the study. The results indicate that the residential environment has been adversely affected by PAHs, lead, and arsenic and should be considered for remediation. PMID:14698928

  7. Lead in Chinese villager house dust: Geographical variation and influencing factors.

    PubMed

    Bi, Xiangyang; Liu, Jinling; Han, Zhixuan; Yang, Wenlin

    2015-12-01

    House dust has been recognized as an important contributor to Pb exposure of children. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The influences of outdoor soil Pb concentrations, dates of construction, house decoration materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with a median concentration of 42 mg/kg. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decoration materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. Principal component analysis (PCA) confirmed that elemental compositions of the house dust were controlled by both anthropogenic and geogenic sources. Using scanning electron microscopy (SEM), the Pb bearing particles in the house dust were also studied. PMID:26381088

  8. [Use of dust and air as indicators of environmental pollution in areas adjacent to a source of stationary lead emission].

    PubMed

    Quiterio, S L; da Silva, C R; Vaitsman, D S; Martinhon, P T; Moreira, M F; Araújo, U C; Mattos, R C; Santos, L S

    2001-01-01

    This study measured lead concentrations in both the outdoor air and household dust from houses located around a lead-acid battery repair shop. Such installations are one of the largest sources of lead exposure, since outdated technology is still used, coupled with the lack of strict air-quality control programs. Measurements of the air lead concentration around the repair shop were carried out at 6 points, approximately 25 and 500 m from the shop. Over 50% of the air samples exceeded the limit of 1.5 microg Pb.m-3 (range 0.03 - 183.3 microg Pb.m-3). House dust samples were collected from 6 places in houses located at approximately 25, 50, and 500 m from the repair shop, and the concentration of 1,500 microg Pb.m-2 for lead in house dust was exceeded in 44% of the samples, with results varying from 2.2 to 54,338.9 microg Pb.m-2. PMID:11395788

  9. Forecasting atmospheric dust loading on Mars using statistics of past observations

    NASA Astrophysics Data System (ADS)

    Montabone, L.; Forget, F.; Millour, E.

    2015-10-01

    The onset of local dust storms on Mars can happen very suddenly, and the development into large regional or even planetary-encircling storms can be rapid and rather unpredictable, taken into account the current knowledge of dust lifting mechanisms and meteorological feedback.

  10. Southeastward Dust Transport during the 16-24 March 2006 Asian Dust Event

    NASA Astrophysics Data System (ADS)

    Tsai, F.; Liu, T.; Hsu, S.; Chen, W.; Tu, J.

    2012-04-01

    Synoptic analyses and regional dust models are applied to analyze the dust measurements obtained during the Asian dust events from 16 to 24 March, 2006, in order to understand the controlling mechanism leading to the dust transport far southeastward of the continent. The southeastward transported dust concentrations measured over Taiwan are traced back to their source areas. By tracing the dust loaded air parcels, the synoptic characteristics of the dust event during generation, transport, and dissipation are inspected and compared with an eastward transported event. It has been found that the synoptic mechanism, rather than the emission intensity, leads to the high dust concentration far southeastward off the continent. Most southeastward moving dust clouds are generated behind the surface front in the descent regions and then transported behind a deep lower-level trough, in which the prevailing northerlies or northwesterlies lead to the southeastward dust transported into the tropics. Without a deep lower-level trough, the dust clouds tend to be transported eastward. Surface lidar observations also show descent of the dust concentrations during their southeastward transport. After moving offshore, the anticyclonic circulation in the leading edge of the surface high circulates the dust parcels ahead of the high-pressure center in a southwestward direction towards the seashore off the Southeast China. With the deceleration of the wind speed, the dust clouds then slowly dissipate over the tropics of the Western Pacific, thus providing nutrients to the marine phytoplanktons.

  11. The modern atmospheric background dust load: Recognition in Central Asian snowpack, and compositional constraints

    USGS Publications Warehouse

    Hinkley, T.; Pertsiger, F.; Zavjalova, L.

    1997-01-01

    Dusts in strata of snowpack in the Alai-Pamir range, Kirghizstan, Central Asia, have chemical compositions that are in the same restricted range as those of the dusts found in snowpacks at three other locations: central south Greenland, the St. Elias range (Alaska), and coastal Antarctica, where special-type local dust sources certainly cannot dominate. This similarity at the four widely separated sites appears to indicate that there is a modern atmospheric background dust that is the same on a regional, hemispheric, or global scale. The common compositional range is that of average crustal rock, or of moderately ferromagnesian volcanic rock. It is not that of carbonate, nor highly siliciceous rocks. Previously, the existence of an atmospheric background dust has been postulated only on the basis of its particle size distribution, and only from observations in polar regions. The present study partially determines the chemical composition of the background dust, and confirms its existence in snowpack at four localities worldwide, including the center of the earth's largest continent where dusts of local source have considerable influence. U.S. copyright. Published in 1997 by the American Geophysical Union.

  12. Effect of leading-edge load constraints on the design and performance of supersonic wings

    NASA Technical Reports Server (NTRS)

    Darden, C. M.

    1985-01-01

    A theoretical and experimental investigation was conducted to assess the effect of leading-edge load constraints on supersonic wing design and performance. In the effort to delay flow separation and the formation of leading-edge vortices, two constrained, linear-theory optimization approaches were used to limit the loadings on the leading edge of a variable-sweep planform design. Experimental force and moment tests were made on two constrained camber wings, a flat uncambered wing, and an optimum design with no constraints. Results indicate that vortex strength and separation regions were mildest on the severely and moderately constrained wings.

  13. Lower tropospheric aerosol loadings over South Africa: The relative contribution of aeolian dust, industrial emissions, and biomass burning

    NASA Astrophysics Data System (ADS)

    Piketh, S. J.; Annegarn, H. J.; Tyson, P. D.

    1999-01-01

    The southern African haze layer is a ubiquitous subcontinental-scale feature of the lower atmosphere that extends to a depth of ˜5 km(˜500 hPa level) on non rain days, particularly in winter. Aerosols derived from biomass burning are commonly thought to contribute substantially to the total background aerosol loading within the layer. It is shown that in both summer and winter this supposition is without foundation over South Africa. Summer and winter aerosol loadings are derived from gravimetric analysis of stacked filter units and from proton-induced X ray emission (PIXE) analysis of one to four hourly resolved streaker samples. From concentrations of eleven inorganic elements, apportionment into four primary sources, biomass burning particulates, aeolian dust, industrial sulphur aerosols, and marine aerosols, has been effected. It is shown that the background biomass burning component of the total aerosol loading over South Africa in general, and within the plume of material being recirculated over South Africa and from there exported from the subcontinent south of 22°S to the Indian Ocean in particular, is minimal in both summer and winter. Except over coastal and adjacent inland areas, marine aerosols likewise make up a small fraction of the total loading. This is particularly so over the inland plateau areas. Crustally-derived aeolian dust and industrially-produced sulphur aerosols are demonstrated to be the major summer and winter constituents of the haze layer over South Africa and the particulate material being transported to the Indian Ocean region. Sulphur is transported within the aerosol plume exiting southern Africa to the Indian Ocean as agglomerates on aeolian dust nuclei.

  14. Assessment of Swine Worker Exposures to Dust and Endotoxin during Hog Load-Out and Power Washing

    PubMed Central

    O’shaughnessy, Patrick; Peters, Thomas; Donham, Kelley; Taylor, Craig; Altmaier, Ralph; Kelly, Kevin

    2012-01-01

    Field measurements of personal and area dust and endotoxin concentrations were obtained while agricultural workers performed two work tasks that have been previously unreported: hog load-out and swine building power washing. Hog load-out involves moving hogs from their pens in finishing buildings into a truck for transport to a meat processor. High pressure power washing is conducted for sanitation purposes after a building has been emptied of hogs to remove surface and floor debris. This debri consists of feed, feces, and hog dander as dust or an encrusted form. The hog load-out process necessarily increases pig activity which is known to increase airborne dust concentrations. An unintended consequence of power washing is that the material covering surfaces is forcibly ejected into the atmosphere, creating the potential for a highly concentrated aerosol exposure to workers. The load-out process resulted in a median personal inhalable mass concentration of 7.14 mg m− 3 and median endotoxin concentration of 12 150 endotoxin units (EU) m− 3. When converted to an 8-h time-weighted average for a ‘total’ sampler, one of the 19 samples exceeded a regulatory limit of 15 mg m− 3. An impinger was used to sample power washing endotoxin concentrations, which resulted in a median personal concentration of 40 350 EU m− 3. These concentrations were among the highest found in the literature for any occupation. With the lack of engineering controls present to reduce airborne contaminant concentrations in swine buildings, either respirator use or a reduction in exposure time is recommended while performing these tasks. PMID:22425653

  15. Lead Speciation in House Dust from Canadian Urban Homes Using EXAFS Micro-XRF and Micro-XRD

    SciTech Connect

    L MacLean; S Beauchemin; P Rasmussen

    2011-12-31

    X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence ({mu}XRF), and micro-X-ray diffraction ({mu}XRD) were used to determine the speciation of Pb in house dust samples from four Canadian urban homes having elevated Pb concentrations (>1000 mg Pb kg{sup -1}). Linear combination fitting of the XAFS data, supported by {mu}XRF and {mu}XRD, shows that Pb is complexed in a variety of molecular environments, associated with both the inorganic and organic fractions of the dust samples. The inorganic species of lead identified were as follows: Pb metal, Pb carbonate, Pb hydroxyl carbonate, Pb oxide, and Pb adsorbed to iron oxyhydroxides. Pb carbonate and/or Pb hydroxyl carbonate occurred in all four dust samples and accounted for 28 to 75% of total Pb. Pb citrate and Pb bound to humate were the organic species identified. The results of this study demonstrate the ability of XAFS to identify Pb speciation in house dust and show the potential to identify Pb sources from new homes versus older homes. Understanding Pb speciation and how it influences bioaccessibility is important for human health risk assessment and risk management decisions which aim to improve indoor environmental health.

  16. Lead speciation in house dust from Canadian urban homes using EXAFS, micro-XRF, and micro-XRD.

    PubMed

    MacLean, Lachlan C W; Beauchemin, Suzanne; Rasmussen, Pat E

    2011-07-01

    X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence (μXRF), and micro-X-ray diffraction (μXRD) were used to determine the speciation of Pb in house dust samples from four Canadian urban homes having elevated Pb concentrations (>1000 mg Pb kg(-1)). Linear combination fitting of the XAFS data, supported by μXRF and μXRD, shows that Pb is complexed in a variety of molecular environments, associated with both the inorganic and organic fractions of the dust samples. The inorganic species of lead identified were as follows: Pb metal, Pb carbonate, Pb hydroxyl carbonate, Pb oxide, and Pb adsorbed to iron oxyhydroxides. Pb carbonate and/or Pb hydroxyl carbonate occurred in all four dust samples and accounted for 28 to 75% of total Pb. Pb citrate and Pb bound to humate were the organic species identified. The results of this study demonstrate the ability of XAFS to identify Pb speciation in house dust and show the potential to identify Pb sources from new homes versus older homes. Understanding Pb speciation and how it influences bioaccessibility is important for human health risk assessment and risk management decisions which aim to improve indoor environmental health. PMID:21591711

  17. Sequential digestion for measuring leachable and total lead in the same sample of dust or paint chips by ICP-MS.

    PubMed

    Le Bot, Barbara; Arcelin, Claire; Briand, Emmanuel; Glorennec, Philippe

    2011-01-01

    House lead exposure is generally assessed using total lead, except in France, where acid-leachable lead is used for routine regulatory purposes. In order to allow an international comparison of French lead dust contamination, a sequential digestion protocol is developed to determine both leachable and total lead on the same sample with a two-step digestion stage: firstly, hydrochloric acid is added to the sample at 37°C to solubilize leachable lead; then nitric acid is added to an aliquot at 95°C to solubilize residual (i.e., non-leachable) lead. Both sample fractions are analyzed with inductively coupled plasma mass spectrometry (ICP-MS). The sum of the two fractions allows to determine total lead. This new protocol has been tested with wiped dust (n = 111) and paint chip (n = 46) samples collected in houses (n = 16). The leachability of lead ranged from 63 to 100% in dust and from 4 to 100% in paint. These findings confirm the strong variability of lead leachability in houses samples and thus the importance of considering it for lead poisoning prevention. This double determination of leachable and total lead for each wiped dust or paint sample appears to be a reproducible, simple, low-cost protocol and thus a useful tool for international comparison of house dust lead contamination. PMID:21104496

  18. The Effect of the Hemochromatosis (HFE) Genotype on Lead Load and Iron Metabolism among Lead Smelter Workers

    PubMed Central

    Fan, Guangqin; Du, Guihua; Li, Huijun; Lin, Fen; Sun, Ziyong; Yang, Wei; Feng, Chang; Zhu, Gaochun; Li, Yanshu; Chen, Ying; Jiao, Huan; Zhou, Fankun

    2014-01-01

    Background Both an excess of toxic lead (Pb) and an essential iron disorder have been implicated in many diseases and public health problems. Iron metabolism genes, such as the hemochromatosis (HFE) gene, have been reported to be modifiers for lead absorption and storage. However, the HFE gene studies among the Asian population with occupationally high lead exposure are lacking. Objectives To explore the modifying effects of the HFE genotype (wild-type, H63D variant and C282Y variant) on the Pb load and iron metabolism among Asian Pb-workers with high occupational exposure. Methods Seven hundred and seventy-one employees from a lead smelter manufacturing company were tested to determine their Pb intoxication parameters, iron metabolic indexes and identify the HFE genotype. Descriptive and multivariate analyses were conducted. Results Forty-five H63D variant carriers and no C282Y variant carrier were found among the 771 subjects. Compared with subjects with the wild-type genotype, H63D variant carriers had higher blood lead levels, even after controlling for factors such as age, sex, marriage, education, smoking and lead exposure levels. Multivariate analyses also showed that the H63D genotype modifies the associations between the blood lead levels and the body iron burden/transferrin. Conclusions No C282Y variant was found in this Asian population. The H63D genotype modified the association between the lead and iron metabolism such that increased blood lead is associated with a higher body iron content or a lower transferrin in the H63D variant. It is indicated that H63D variant carriers may be a potentially highly vulnerable sub-population if they are exposed to high lead levels occupationally. PMID:24988074

  19. Inattentional Deafness: Visual Load Leads to Time-Specific Suppression of Auditory Evoked Responses

    PubMed Central

    Molloy, Katharine; Griffiths, Timothy D.; Lavie, Nilli

    2015-01-01

    Due to capacity limits on perception, conditions of high perceptual load lead to reduced processing of unattended stimuli (Lavie et al., 2014). Accumulating work demonstrates the effects of visual perceptual load on visual cortex responses, but the effects on auditory processing remain poorly understood. Here we establish the neural mechanisms underlying “inattentional deafness”—the failure to perceive auditory stimuli under high visual perceptual load. Participants performed a visual search task of low (target dissimilar to nontarget items) or high (target similar to nontarget items) load. On a random subset (50%) of trials, irrelevant tones were presented concurrently with the visual stimuli. Brain activity was recorded with magnetoencephalography, and time-locked responses to the visual search array and to the incidental presence of unattended tones were assessed. High, compared to low, perceptual load led to increased early visual evoked responses (within 100 ms from onset). This was accompanied by reduced early (∼100 ms from tone onset) auditory evoked activity in superior temporal sulcus and posterior middle temporal gyrus. A later suppression of the P3 “awareness” response to the tones was also observed under high load. A behavioral experiment revealed reduced tone detection sensitivity under high visual load, indicating that the reduction in neural responses was indeed associated with reduced awareness of the sounds. These findings support a neural account of shared audiovisual resources, which, when depleted under load, leads to failures of sensory perception and awareness. SIGNIFICANCE STATEMENT The present work clarifies the neural underpinning of inattentional deafness under high visual load. The findings of near-simultaneous load effects on both visual and auditory evoked responses suggest shared audiovisual processing capacity. Temporary depletion of shared capacity in perceptually demanding visual tasks leads to a momentary reduction in

  20. Lead isotopes combined with a sequential extraction procedure for source apportionment in the dry deposition of Asian dust and non-Asian dust.

    PubMed

    Lee, Pyeong-Koo; Yu, Soonyoung

    2016-03-01

    Lead isotopic compositions were determined in leachates that were generated using sequential extractions of dry deposition samples of Asian dust (AD) and non-Asian dust (NAD) and Chinese desert soils, and used to apportion Pb sources. Results showed significant differences in (206)Pb/(207)Pb and (206)Pb/(204)Pb isotopic compositions in non-residual fractions between the dry deposition samples and the Chinese desert soils while (206)Pb/(207)Pb and (206)Pb/(204)Pb isotopic compositions in residual fraction of the dry deposition of AD and NAD were similar to the mean (206)Pb/(207)Pb and (206)Pb/(204)Pb in residual fraction of the Alashan Plateau soil. These results indicate that the geogenic materials of the dry deposition of AD and NAD were largely influenced by the Alashan Plateau soil, while the secondary sources of the dry deposition were different from those of the Chinese desert soils. In particular, the lead isotopic compositions in non-residual fractions of the dry deposition were homogenous, which implies that the non-residual four fractions (F1 to F4) shared the primary anthropogenic origin. (206)Pb/(207)Pb values and the predominant wind directions in the study area suggested that airborne particulates of heavily industrialized Chinese cities were one of the main Pb sources. Source apportionment calculations showed that the average proportion of anthropogenic Pb in the dry deposition of AD and NAD was 87% and 95% respectively in total Pb extraction, 92% and 97% in non-residual fractions, 15% and 49% in residual fraction. Approximately 81% and 80% of the anthropogenic Pb was contributed by coal combustion in China in the dry deposition of AD and NAD respectively while the remainder was derived from industrial Pb contamination. The research result proposes that sequential extractions with Pb isotope analysis are a useful tool for the discrimination of anthropogenic and geogenic origins in highly contaminated AD and NAD. PMID:26708760

  1. Road dust lead (Pb) in two neighborhoods of urban Atlanta, (GA, USA).

    PubMed

    Deocampo, Daniel M; Reed, Jack; Kalenuik, Alexander P

    2012-06-01

    Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust (<250 µm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution. PMID:22829787

  2. Road Dust Lead (Pb) in Two Neighborhoods of Urban Atlanta, (GA, USA)

    PubMed Central

    Deocampo, Daniel M.; Reed, Jack; Kalenuik, Alexander P.

    2012-01-01

    Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust (<250 µm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution. PMID:22829787

  3. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... fume, calculated as lead (Pb), per cubic meter of air. (d) The fume will be generated by impinging an..., which is analyzed and calculated as lead (Pb), shall not exceed 1.5 milligrams of lead for a...

  4. [Magnetic Response of Dust-loaded Leaves in Parks of Shanghai to Atmospheric Heavy Metal Pollution].

    PubMed

    Liu, Fei; Chu, Hui-min; Zheng, Xiang-min

    2015-12-01

    To reveal the magnetic response to the atmospheric heavy metal pollution in leaves along urban parks, Camphor leaf samples, widely distributed at urban parks, were collected along the year leading wind direction of Shanghai, by setting two vertical and horizontal sections, using rock magnetic properties and heavy metal contents analysis. The results showed that the magnetic minerals of samples were predominated by ferromagnetic minerals, and both the concentration and grain size of magnetite particles gradually decreased with the winter monsoon direction from the main industrial district. A rigorous cleaning of leaves using ultrasonic agitator washer could remove about 63%-90% of low-field susceptibility values of the leaves, and this strongly indicated that the intensity of magnetic signal was mainly controlled by the PMs accumulated on the leaves surfaces. Moreover, there was a significant linear relationship between heavy metals contents (Fe, Mn, Zn, Cu, Cr, V and Pb) and magnetic parameters (0.442 ≤ R ≤ 0.799, P < 0.05), which suggested that magnetic parameters of urban park leaves could be used as a proxy for atmospheric heavy metal pollution. The results of multivariate statistical analysis showed that the content of magnetic minerals and heavy metal indust-loaded tree leaves was affected by associated pollution of industry and traffic. PMID:27011970

  5. Large lead/acid batteries for frequency regulation, load levelling and solar power applications

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    Lead/acid batteries are suitable for a multitude of utility applications. This paper presents some examples where large lead/acid batteries have been used for frequency regulation, load levelling and solar power applications. The operational experiences are given together with a discussion about the design and technical specialities of these batteries. In 1986, a 17 MW/14 MWh battery was installed at BEWAG in Berlin which, at that time, was the largest lead/acid battery in the world. Designed to strengthen Berlin's 'island' system, it was used since the beginning of 1987 for frequency regulation and spinning reserve. In December 1993, when Berlin was connected to the electricity grid, frequency regulation was no longer required but the battery was still used for spinning reserve. For many years, the industrial battery plant of Hagen in Soest has used a large lead/acid battery for load levelling. The experience gained during more than ten years shows that load levelling and peak shaving can be a marked benefit for customers and utilities with regard to reducing their peak demand. In the summer of 1992, a 216 V and 2200 Ah lead/acid battery with positive tubular plates and gelled electrolyte was installed at a solar power plant in Flanitzhutte, a small village in the south of Germany which is not connected to the electricity grid. A report is given of the first years of use and includes a discussion about the best charge strategy for such gel batteries when used for solar power applications.

  6. Lead poisoning

    MedlinePlus

    ... swallows a lead object or breathes in lead dust, some of the poison can stay in the ... a health problem. Lead is everywhere, including dirt, dust, new toys, and old house paint. Unfortunately, you ...

  7. Removal of lead by using Raschig rings manufactured with mixture of cement kiln dust, zeolite and bentonite.

    PubMed

    Salem, A; Afshin, H; Behsaz, H

    2012-07-15

    The present investigation is a follow-up of study on manufacturing Raschig ring for removal of lead from aqueous solution. The mixtures were formulated using cement kiln dust, zeolite, and bentonite, normally used as natural adsorbents in the industrial scale, according to mixture design algorithm and response surface method. The pastes were prepared by addition of 28.0wt.% de-ionized water, containing 0.1wt.% carboxymethyl cellulose, with mixed powders. The adsorbents were fabricated by extrusion of the pastes in Raschig ring form and calcination at 500°C after drying in oven. The effects of starting materials on the mechanical behavior of rings were studied from view point of mixture design algorithm to optimize the adsorbent composition. This method demonstrated to yield valuable information on the effects of used materials on mechanical characteristics. The study concluded that the strength, reliability and sorption capacity of ring can be simultaneously optimized by the addition of 47.5wt.% cement kiln dust, 32.5wt.% zeolite, and 20.0wt.% bentonite. In the next part of work, the sorption kinetics was investigated. The kinetic study indicated that the modified model can successfully correlate the sorption data. The equilibrium result showed the possibility of lead immobilization by fabricated rings. PMID:22608209

  8. Lead, mercury, cadmium, chromium, nickel, copper, zinc, calcium, iron, manganese and chromium (VI) levels in Nigeria and United States of America cement dust.

    PubMed

    Ogunbileje, J O; Sadagoparamanujam, V-M; Anetor, J I; Farombi, E O; Akinosun, O M; Okorodudu, A O

    2013-03-01

    This study was aimed at investigating the relative abundance of heavy metals in cement dust from different cement dust factories in order to predict their possible roles in the severity of cement dust toxicity. The concentrations of total mercury (Hg), copper (Cu), chromium (Cr), cadmium (Cd), nickel (Ni), manganese (Mn), lead (Pb), iron (Fe) and chromium (VI) (Cr (VI)) levels in cement dust and clinker samples from Nigeria and cement dust sample from the United States of America (USA) were determined using graphite furnace atomic absorption (GFAAS), while Zn and Ca were measured by flame atomic absorption spectrophotometry (FAAS), and Cr (VI) by colorimetric method. Total Cu, Ni and Mn were significantly higher in cement dust sample from USA (p<0.05), also, both total Cr and Cr (VI) were 5.4-26 folds higher in USA cement dust compared with Nigeria cement dust or clinker (p<0.001). Total Cd was higher in both Nigeria cement dust and clinker (p<0.05 and p<0.001), respectively. Mercury was more in both Nigeria cement dust and clinker (p<0.05), while Pb was only significantly higher in clinker from Nigeria (p<0.001). These results show that cement dust contain mixture of metals that are known human carcinogens and also have been implicated in other debilitating health conditions. Additionally, it revealed that metal content concentrations are factory dependent. This study appears to indicate the need for additional human studies relating the toxicity of these metals and their health impacts on cement factory workers. PMID:23261125

  9. Critical loads for lead in France: First results on forest soils

    NASA Astrophysics Data System (ADS)

    Probst, A.; Moncoulon, D.; Godderis, Y.; Hernandez, L.; Party, J.-P.

    2003-05-01

    Within the framework of the United Nation Convention on Long Range Transboundary Air Pollution, France is part of the Working Group on Effect which aims at evaluating the impact of atmospheric deposition on ecosystems by calculating critical loads. The “critical loads” are “the highest deposition of compounds that will not cause chemical changes in soil leading to long-term harmful effects on ecosystem structure and function”. A guidance manual for calculation of critical loads for heavy metals (lead and cadmium) has been proposed by the Coordination Center for Effects (executive body of the WGE). French National Focal Center (CNRS and ADEME) aims in this study at evaluating the accuracy of the european methodology for calculation of critical loads for french forest soils. It appears that critical load approach is adapted for France but need to be calibrated at least for calculation of weathering fluxes and determination of critical limits. Stand-still on the contrary is not adequate because of inherent contradictions in the method and too much uncertainties in the transfer functions.

  10. Low-speed cascade investigation of loaded leading-edge compressor blades

    NASA Technical Reports Server (NTRS)

    Emery, James C

    1956-01-01

    Six percent thick NACA 63-series compressor-blade sections having a loaded leading-edge A4K6 mean line have been investigated systematically in a two-dimensional porous-wall cascade over a range of Reynolds numbers from 160,000 to 385,000. Blades cambered to have isolated-airfoil lift coefficients of 0.6, 1.2, 1.8, and 2.4 were tested over the usable angle-of-attack range at inlet-air angles of 30 degrees, 45 degrees, and 60 degrees and solidities of 1.0 and 1.5. A comparison with data of NACA RM L51G31, shows that the angle-of-attack operating range is 2 degrees to 4 degrees less than the range for the uniformly loaded section; however, the wake losses near design angle of attack are slightly lower than those for the uniformly loaded section. Except for highly cambered blades at high inlet angles, the 63-(C s oA4K6)06 compressor-blade sections are capable of more efficient operation for moderate-speed subsonic compressors at design angle of attack than are the 65-(C s oa10)10 or the 65-(c s oA2I8b)10 compressor-blade sections. In contrast to the other sections, the loaded leading-edge sections are capable of operating efficiently at the lower Reynolds numbers.

  11. Effects of Nose Radius and Aerodynamic Loading on Leading Edge Receptivity

    NASA Technical Reports Server (NTRS)

    Hammerton, P. W.; Kerschen, E. J.

    1998-01-01

    An analysis is presented of the effects of airfoil thickness and mean aerodynamic loading on boundary-layer receptivity in the leading-edge region. The case of acoustic free-stream disturbances, incident on a thin cambered airfoil with a parabolic leading edge in a low Mach number flow, is considered. An asymptotic analysis based on large Reynolds number is developed, supplemented by numerical results. The airfoil thickness distribution enters the theory through a Strouhal number based on the nose radius of the airfoil, S = (omega)tau(sub n)/U, where omega is the frequency of the acoustic wave and U is the mean flow speed. The influence of mean aerodynamic loading enters through an effective angle-of-attack parameter ti, related to flow around the leading edge from the lower surface to the upper. The variation of the receptivity level is analyzed as a function of S, mu, and characteristics of the free-stream acoustic wave. For an unloaded leading edge, a finite nose radius dramatically reduces the receptivity level compared to that for a flat plate, the amplitude of the instability waves in the boundary layer being decreased by an order of magnitude when S = 0.3. Modest levels of aerodynamic loading are found to further decrease the receptivity level for the upper surface of the airfoil, while an increase in receptivity level occurs for the lower surface. For larger angles of attack close to the critical angle for boundary layer separation, a local rise in the receptivity level occurs for the upper surface, while for the lower surface the receptivity decreases. The effects of aerodynamic loading are more pronounced at larger values of S. Oblique acoustic waves produce much higher receptivity levels than acoustic waves propagating downstream parallel to the airfoil chord.

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

    PubMed

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

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources. PMID:27376990

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

    PubMed

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

    2016-02-01

    Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at "low pollution risk" status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas. PMID:26490894

  14. Interactive Soil Dust Aerosol Model in the GISS GCM. Part 1; Sensitivity of the Soil Dust Cycle to Radiative Properties of Soil Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Perlwitz, Jan; Tegen, Ina; Miller, Ron L.

    2000-01-01

    The sensitivity of the soil dust aerosol cycle to the radiative forcing by soil dust aerosols is studied. Four experiments with the NASA/GISS atmospheric general circulation model, which includes a soil dust aerosol model, are compared, all using a prescribed climatological sea surface temperature as lower boundary condition. In one experiment, dust is included as dynamic tracer only (without interacting with radiation), whereas dust interacts with radiation in the other simulations. Although the single scattering albedo of dust particles is prescribed to be globally uniform in the experiments with radiatively active dust, a different single scattering albedo is used in those experiments to estimate whether regional variations in dust optical properties, corresponding to variations in mineralogical composition among different source regions, are important for the soil dust cycle and the climate state. On a global scale, the radiative forcing by dust generally causes a reduction in the atmospheric dust load corresponding to a decreased dust source flux. That is, there is a negative feedback in the climate system due to the radiative effect of dust. The dust source flux and its changes were analyzed in more detail for the main dust source regions. This analysis shows that the reduction varies both with the season and with the single scattering albedo of the dust particles. By examining the correlation with the surface wind, it was found that the dust emission from the Saharan/Sahelian source region and from the Arabian peninsula, along with the sensitivity of the emission to the single scattering albedo of dust particles, are related to large scale circulation patterns, in particular to the trade winds during Northern Hemisphere winter and to the Indian monsoon circulation during summer. In the other regions, such relations to the large scale circulation were not found. There, the dependence of dust deflation to radiative forcing by dust particles is probably

  15. Estimating Children’s Soil/Dust Ingestion Rates through Retrospective Analyses of Blood Lead Biomonitoring from the Bunker Hill Superfund Site in Idaho

    PubMed Central

    von Lindern, Ian; Spalinger, Susan; Stifelman, Marc L.; Stanek, Lindsay Wichers; Bartrem, Casey

    2016-01-01

    Background: Soil/dust ingestion rates are important variables in assessing children’s health risks in contaminated environments. Current estimates are based largely on soil tracer methodology, which is limited by analytical uncertainty, small sample size, and short study duration. Objectives: The objective was to estimate site-specific soil/dust ingestion rates through reevaluation of the lead absorption dose–response relationship using new bioavailability data from the Bunker Hill Mining and Metallurgical Complex Superfund Site (BHSS) in Idaho, USA. Methods: The U.S. Environmental Protection Agency (EPA) in vitro bioavailability methodology was applied to archived BHSS soil and dust samples. Using age-specific biokinetic slope factors, we related bioavailable lead from these sources to children’s blood lead levels (BLLs) monitored during cleanup from 1988 through 2002. Quantitative regression analyses and exposure assessment guidance were used to develop candidate soil/dust source partition scenarios estimating lead intake, allowing estimation of age-specific soil/dust ingestion rates. These ingestion rate and bioavailability estimates were simultaneously applied to the U.S. EPA Integrated Exposure Uptake Biokinetic Model for Lead in Children to determine those combinations best approximating observed BLLs. Results: Absolute soil and house dust bioavailability averaged 33% (SD ± 4%) and 28% (SD ± 6%), respectively. Estimated BHSS age-specific soil/dust ingestion rates are 86–94 mg/day for 6-month- to 2-year-old children and 51–67 mg/day for 2- to 9-year-old children. Conclusions: Soil/dust ingestion rate estimates for 1- to 9-year-old children at the BHSS are lower than those commonly used in human health risk assessment. A substantial component of children’s exposure comes from sources beyond the immediate home environment. Citation: von Lindern I, Spalinger S, Stifelman ML, Stanek LW, Bartrem C. 2016. Estimating children’s soil/dust ingestion

  16. Dust Studies in DIII-D Tokamak

    SciTech Connect

    Rudakov, D L; West, W P; Groth, M; Yu, J H; Boedo, J A; Bray, B D; Brooks, N H; Fenstermacher, M E; Hollmann, E M; Hyatt, A W; Krasheninnikov, S I; Lasnier, C J; Moyer, R A; Pigarov, A Y; Smirnov, R; Solomon, W M; Wong, C C

    2008-04-15

    Studies of submicron dust using Mie scattering from Nd:YAG lasers and video data of micron to sub-millimeter sized dust on DIII-D tokamak have provided the first data of dust sources and transport during tokamak discharges. During normal operation on DIII-D dust observation rates are low, a few events per discharge or less. The net carbon content of the dust corresponds to a carbon atom density a few orders of magnitude below the core impurity density. Statistical analysis of Mie data collected over months of operation reveal correlation of increased dust rate with increased heating power and impulsive wall loading due to edge localized modes (ELMs) and disruptions. Generation of significant amounts of dust by disruptions is confirmed by the camera data. However, dust production by disruptions alone is insufficient to account for estimated in-vessel dust inventory in DIII-D. After an extended entry vent, thousands of dust particles are observed by cameras in the first 2-3 plasma discharges. Individual particles moving at velocities up to {approx}300 m/s, breakup of larger particles into pieces, and collisions of particles with walls are observed. After {approx}70 discharges, dust levels are reduced to a few events per discharge. In order to calibrate diagnostics and benchmark modeling, milligram amounts of micron-sized carbon dust have been injected into DIII-D discharges, leading to the core carbon density increase by a factor of 2-3. Following injection, dust trajectories in the divertor are mostly in the toroidal direction, consistent with the ion drag force. Dust from the injection is observed in the outboard midplane by a fast framing camera. The observed trajectories and velocities of the dust particles are in qualitative agreement with modeling by the 3D DustT code.

  17. Dust Studies in DIII-D Tokamak

    SciTech Connect

    Rudakov, D. L.; Yu, J. H.; Boedo, J. A.; Hollmann, E. M.; Krasheninnikov, S. I.; Moyer, R. A.; Pigarov, A. Yu.; Smirnov, R.; West, W. P.; Bray, B. D.; Brooks, N. H.; Hyatt, A. W.; Wong, C. P. C.; Groth, M.; Fenstermacher, M. E.; Lasnier, C. J.; Solomon, W. M.

    2008-09-07

    Studies of submicron dust using Mie scattering from Nd:YAG lasers and video data of micron to sub-millimeter sized dust on DIII-D tokamak have provided the first data of dust sources and transport during tokamak discharges. During normal operation on DIII-D dust observation rates are low, a few events per discharge or less. The net carbon content of the dust corresponds to a carbon atom density a few orders of magnitude below the core impurity density. Statistical analysis of Mie data collected over months of operation reveal correlation of increased dust rate with increased heating power and impulsive wall loading due to edge localized modes (ELMs) and disruptions. Generation of significant amounts of dust by disruptions is confirmed by the camera data. However, dust production by disruptions alone is insufficient to account for estimated in-vessel dust inventory in DIII-D. After an extended entry vent, thousands of dust particles are observed by cameras in the first 2-3 plasma discharges. Individual particles moving at velocities up to {approx}300 m/s, breakup of larger particles into pieces, and collisions of particles with walls are observed. After {approx}70 discharges, dust levels are reduced to a few events per discharge. In order to calibrate diagnostics and benchmark modeling, milligram amounts of micron-sized carbon dust have been injected into DIII-D discharges, leading to the core carbon density increase by a factor of 2-3. Following injection, dust trajectories in the divertor are mostly in the toroidal direction, consistent with the ion drag force. Dust from the injection is observed in the outboard midplane by a fast framing camera. The observed trajectories and velocities of the dust particles are in qualitative agreement with modeling by the 3D DustT code.

  18. Shaped, lead-loaded acrylic filters for patient exposure reduction and image-quality improvement

    SciTech Connect

    Gray, J.E.; Stears, J.G.; Frank, E.D.

    1983-03-01

    Shaped filters that are constructed of lead-loaded acrylic material for use in patient radiography are discussed. Use of the filters will result in improved overall image quality with significant exposure reduction to the patient (approximately a 2X reduction in breast exposure and a 3X reduction in thyroid gland exposure). Detailed drawings of the shaped filters for scoliosis radiography, cervical spine radiography, and for long film changers in special procedures are provided. The use of the scoliosis filters is detailed and includes phantom and patient radiographs and dose reduction information.

  19. Utilization of phosphorus loaded alkaline residue to immobilize lead in a shooting range soil.

    PubMed

    Yan, Yubo; Qi, Fangjie; Seshadri, Balaji; Xu, Yilu; Hou, Jiexi; Ok, Yong Sik; Dong, Xiaoli; Li, Qiao; Sun, Xiuyun; Wang, Lianjun; Bolan, Nanthi

    2016-11-01

    The alkaline residue generated from the production of soda ash using the ammonia-soda method has been successfully used in removing phosphorus (P) from aqueous solution. But the accumulation of P-containing solid after P removal is an undesirable menace to the environment. To achieve the goal of recycling, this study explored the feasibility of reusing the P loaded alkaline residue as an amendment for immobilization of lead (Pb) in a shooting range soil. The main crystalline phase and micromorphology of amendments were determined using X-ray diffraction (XRD) and scanning electron microscopy-electron dispersion spectroscopy (SEM-EDS) methods. The toxicity characteristic leaching procedure (TCLP), sequential extraction procedure, and physiologically based extraction test (PBET) were employed to evaluate the effectiveness of Pb immobilization in soil after 45 d incubation. Treatment with P loaded alkaline residue was significantly effective in reducing the TCLP and PBET extractable Pb concentrations in contrast to the untreated soil. Moreover, a positive change in the distribution of Pb fractions was observed in the treated soil, i.e., more than 60% of soil-Pb was transformed to the residual fraction compared to the original soil. On the other hand, P loaded amendments also resulted in a drastic reduction in phytoavailable Pb to the winter wheat and a mild release of P as a nutrient in treated soil, which also confirmed the improvement of soil quality. PMID:27513552

  20. Simulating Mars' Dust Cycle with a Mars General Circulation Model: Effects of Water Ice Cloud Formation on Dust Lifting Strength and Seasonality

    NASA Technical Reports Server (NTRS)

    Kahre, Melinda A.; Haberle, Robert; Hollingsworth, Jeffery L.

    2012-01-01

    The dust cycle is critically important for the current climate of Mars. The radiative effects of dust impact the thermal and dynamical state of the atmosphere [1,2,3]. Although dust is present in the Martian atmosphere throughout the year, the level of dustiness varies with season. The atmosphere is generally the dustiest during northern fall and winter and the least dusty during northern spring and summer [4]. Dust particles are lifted into the atmosphere by dust storms that range in size from meters to thousands of kilometers across [5]. Regional storm activity is enhanced before northern winter solstice (Ls200 degrees - 240 degrees), and after northern solstice (Ls305 degrees - 340 degrees ), which produces elevated atmospheric dust loadings during these periods [5,6,7]. These pre- and post- solstice increases in dust loading are thought to be associated with transient eddy activity in the northern hemisphere with cross-equatorial transport of dust leading to enhanced dust lifting in the southern hemisphere [6]. 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 [8,9,10]. 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.

  1. Retrieval of dust aerosols during night: improved assessment of long wave dust radiative forcing over Afro-Asian regions

    NASA Astrophysics Data System (ADS)

    Deepshikha, S.; Srinivasan, J.

    2010-08-01

    Several investigators in the past have used the radiance depression (with respect to clear-sky infrared radiance), resulting from the presence of mineral dust aerosols in the atmosphere, as an index of dust aerosol load in the atmosphere during local noon. Here, we have used a modified approach to retrieve dust index during night since assessment of diurnal average infrared dust forcing essentially requires information on dust aerosols during night. For this purpose, we used infrared radiance (10.5-12.5 μm), acquired from the METEOSAT-5 satellite (~ 5 km resolution). We found that the "dust index" algorithm, valid for daytime, will no longer hold during the night because dust is then hotter than the theoretical dust-free reference. Hence we followed a "minimum reference" approach instead of a conventional "maximum reference" approach. A detailed analysis suggests that the maximum dust load occurs during the daytime. Over the desert regions of India and Africa, maximum change in dust load is as much as a factor of four between day and night and factor of two variations are commonly observed. By realizing the consequent impact on long wave dust forcing, sensitivity studies were carried out, which indicate that utilizing day time data for estimating the diurnally averaged long-wave dust radiative forcing results in significant errors (as much as 50 to 70%). Annually and regionally averaged long wave dust radiative forcing (which account for the diurnal variation of dust) at the top of the atmosphere over Afro-Asian region is 2.6 ± 1.8 W m-2, which is 30 to 50% lower than those reported earlier. Our studies indicate that neglecting diurnal variation of dust while assessing its radiative impact leads to an overestimation of dust radiative forcing, which in turn result in underestimation of the radiative impact of anthropogenic aerosols.

  2. Reinstating lead for high-loaded efficient negative electrode for rechargeable sodium-ion battery

    NASA Astrophysics Data System (ADS)

    Darwiche, Ali; Dugas, Romain; Fraisse, Bernard; Monconduit, Laure

    2016-02-01

    Due to its weight and toxicity, Pb is usually not considered as possible anode for Li- and Na-ion (NIBs) batteries. Nevertheless the toxicity is related to specific applications and its recycling is more than 99% which is one of the highest recycling rates on the planet where no other power source is utilized in more applications with such sustainability. For this reason, we have investigated micrometric lead particles as electrode for NIBs in an ether-based electrolyte (1 M NaPF6 in diglyme). The cyclability, coulombic efficiency and rate capability of lead were unexpected. A high loaded lead electrode with 98%wt of Pb and only 1% of carbon additive showed i) a capacity retention of 464 mA h/g after 50 cycles with only 1.5% of capacity loss, which represents a high volumetric capacity of 5289 mA h/cm3 due to the high density of Pb and ii) a very interesting capacity retention even at high current rate (1950 mA/g). In situ XRD study confirmed a sodiation-desodiation process in four steps. Preliminary tests in Pb//Na3V2(PO4)2F3 full cells showed promising results demonstrating that Pb could be a practical candidate for future high energy density Na-ion batteries with an efficient sodiated or non sodiated positive electrode.

  3. Extremely high aerosol loading over Arabian Sea during June 2008: The specific role of the atmospheric dynamics and Sistan dust storms

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Rashki, A.; Houssos, E. E.; Goto, D.; Nastos, P. T.

    2014-09-01

    This study focuses on analyzing the extreme aerosol loading and the mechanisms, source areas and meteorological conditions that favored the abnormal dust exposure towards Arabian Sea during June 2008. The analysis reveals that the spatial-averaged aerosol optical depth (AOD) over Arabian Sea in June 2008 is 0.5 (78.2%) higher than the 2000-2013 mean June value and is mostly attributed to the enhanced dust activity and several (18) dust storms originated from the Sistan region (Iran-Afghanistan borders). Landsat images show that the marshy lakes in Sistan basin got dried during the second half of June 2008 and the alluvial silt and saline material got easily eroded by the intense Levar winds, which were stronger (>15-20 m s-1) than the climatological mean for the month of June. These conditions led to enhanced dust exposure from Sistan that strongly affected the northern and central parts of the Arabian Sea, as forward air-mass trajectories show. The NCEP/NCAR reanalysis reveals an abnormal intensification and spatial expansion of the Indian low pressure system towards northern Arabian Sea in June 2008. This suggests strengthening of the convection over the arid southwest Asia and exposure of significant amount of dust, which can reach further south over Arabian Sea favored by the enhanced cyclonic circulation. MODIS imagery highlighted several dust storms originated from Sistan and affecting Arabian Sea during June 2008, while the SPRINTARS model simulations of increased AOD and dust concentration over Sistan and downwind areas are in agreement with ground-based and satellite observations.

  4. Comparison of Lead Species in Household Dust Wipes, Soil, and Airborne Particulate Matter in El Paso, Texas, by X-Ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pingitore, N. E.; Clague, J.; Amaya, M. A.

    2006-12-01

    Understanding the interplay of indoor and outdoor sources of lead in an urban setting is one foundation in establishing risk for lead exposure in children in our cities. A household may be the source for lead contamination due to the deterioration of interior lead-based paint, or a sink if lead particles are tracked or blown into the home from such potential ambient sources as yard soil or urban street dust. In addressing this issue, X-Ray Absorption Spectroscopy (XAS) presents the opportunity to directly and quantitatively speciate lead at low concentrations in bulk samples. We performed XAS analyses on dust wipes from window sills or floors from 8 houses that exceeded Federal standards for lead in dust. We entered these data into a Principal Components Analysis (PCA) that also included El Paso environmental samples: lead-based paints, soils, and airborne particulate matter. A simple two-component mixing system accounted for more than 95% of the variance of this data set. Paint and lead oxide appear to be the principal components, with all the samples falling in a compositional range from pure paint to 75% paint, 25% lead oxide. Note that several different lead compounds are possible constituents of a given lead-based paint. The paints spread from one end out along perhaps a fifth of the range of the compositional axis, followed closely, but not overlapped, by the soil samples, which covered the remainder of the compositional range. Two of the dust wipes plotted within the paint range, and the remaining 6 dust wipes plotted randomly through the soil range. Samples of airborne particulate matter plotted in both the paint and soil ranges. These observations suggest that the lead on most of the dust wipes originated outside the house, probably from deteriorated exterior lead-based paint deposited in adjacent yards. This paint mixed with lead oxide present in the soil and entered the houses by the airborne route. The probable source of the oxide in the soil is former

  5. Physical characterization, magnetic measurements, REE geochemistry and biomonitoring of dust load accumulated during a protracted winter fog period and their implications.

    PubMed

    Chakarvorty, Munmun; Pati, Jayanta Kumar; Patil, Shiva Kumar; Shukla, Swati; Niyogi, Ambalika; Saraf, Arun Kumar

    2014-05-01

    The winter fog in India is a recurrent phenomenon for more than a decade now affecting the entire Himalayan and sub-Himalayan regions covering an area of nearly 500,000 km(2). Every winter (December-January), the air and surface transports in cities of northern India (Amritsar, New Delhi, Agra, Gwalior, Kanpur, Lucknow, and Allahabad) are severely disrupted with visibility reduced to <50 m at times. Since dust particles are known to act as nuclei for the fog formation, this study is aimed to carry out physicochemical characterization of the dust particulates accumulated during a protracted fog period from one of the severely fog affected cities of north India (Allahabad; 25°27'33.40″N-81°52'45.47″E). The dust-loaded tree leaves belonging to Ficus bengalensis and Ficus religiosa from 50 different locations between January 24 and 31, 2010 are sampled and characterized. The mass of dust, color, grain shape, size, phase constituents, and mineral magnetic parameters, such as magnetic susceptibility, SIRM, χ fd%, and S-ratio, show minor variation and the regional influence outweighs local anthropogenic contributions. The dust compositions show fractionated rare earth element pattern with a pronounced negative Eu anomaly similar to upper continental crust and further suggesting their derivation from sources located in parts of north and central India. PMID:24407961

  6. Elucidating the Linkage Between Changes in Land Use, Atmospheric Mineral Dust Loading, and Precipitation in Central Asia During the Past 50-years

    NASA Astrophysics Data System (ADS)

    Sokolik, I. N.; Tatarskii, V. V.; Razuvaev, V. N.; Knight, R. W.; Enloe, J. G.

    2004-12-01

    It is believed that both land-use/land cover changes and atmospheric mineral dust are among the main factors controlling the precipitation and hydrological cycle. Over the past 50-years Central Asia has been undergoing major human-induced land-use changes that altered the geographical area and intensity of dust sources. Desiccation of the Aral Sea and conversion of the steppe in Kazakhstan to the agriculture fields are just a few examples of occurred land-use changes. Interactions of precipitation with land use changes and atmospheric dust can occur at a variety of scales through a poorly understood series of feedback mechanisms. This study addresses this issue by performing a detailed analysis of empirical data at a variety of spatial and temporal scales. The 50-year daily precipitation observations reported from ground-based stations in Central Asia were analyzed to 1) determine the changes in the precipitation distribution and trends and 2) elucidate the potential linkages between precipitation trends and land use and dust loading changes. Utilizing several statistical techniques, we analyzed the precipitation time series for the individual stations as well as for a subset of the stations considering different time-averaging. Several criteria were used to group the stations to separate those affected by dust transport and/or by same types of land-use changes. The consistency between observed precipitation trends and those predicted by the models will be discussed.

  7. Strength Properties of Aged Poled Lead Zirconate Titanate Subjected to Electromechanical Loadings

    SciTech Connect

    Zhang, Kewei; Zeng, Fan W; Wang, Hong; Lin, Hua-Tay

    2012-01-01

    Electric field and aging time are two important factors that affect the mechanical strength and long-term reliability of lead zirconate titanate or PZT actuators. In the present work, a commercial PZT-5A aged four years was examined using ball-on-ring (BoR) mechanical testing under coupled electric fields. The electric field range of -3E{sub c} to +3E{sub c} (E{sub c}, coercive electric field) was studied (i.e., -3E{sub c}, -E{sub c}, 0, +E{sub c}, +2E{sub c}, and +3E{sub c}) with a controlled electric loading path. A Weibull distribution was used to interpret the mechanical strength data. With an electric field preloaded from 0 to -3E{sub c}, it was found that subsequent increases in the electric field resulted in an asymmetrical V-shaped curve of mechanical strength against the electric field. The bottom of the V curve was located near the zero electric field level. Microscopy analysis showed that pores were the strength limiter for the tested PZT under electromechanical loadings.

  8. Life evaluation of valve-regulated lead-acid batteries for load-leveling applications

    NASA Astrophysics Data System (ADS)

    Deluca, W. H.; Miller, J. F.; Webster, C. E.; Hogrefe, R. L.

    Argonne National Laboratory (ANL) has initiated a test program to evaluate the suitability of valve-regulated lead-acid (VRLA) batteries for use in deep-discharge cycling applications. The program includes the examination of VRLA batteries of the gelled-electrolyte design and the absorbed-electrolyte type. This work is sponsored by the Electric Power Research Institute (EPRI) and the International Lead Zinc Research Organization (ILZRO). While VRLA batteries have found use in standby and uninterruptable power source applications, insufficient data are available to determine their performance and life in repetitive cycling applications. The objectives of the ANL test plan are: (1) to use accelerated testing techniques to obtain evidence within a 6 month test period that indicate an expected life in a utility operating environment; (2) to determine VRLA battery life within a 2 to 3 year time period under conditions (temperature and depth-of-discharge) that closely simulate those encountered in load-leveling operations; and (3) to assess the applicability and usefulness of accelerated testing procedures for deep-discharge cycling applications.

  9. Hydrometallurgical recovery of zinc and lead from electric arc furnace dust using mononitrilotriacetate anion and hexahydrated ferric chloride.

    PubMed

    Leclerc, Nathalie; Meux, Eric; Lecuire, Jean Marie

    2002-04-26

    The purpose of this work was to study the feasibility at laboratory-scale of a new hydrometallurgical process for treating electric arc furnace dusts (EAFD). The proposed process is intended to extract zinc and lead from EAFD without destroying the iron oxides matrix. So, this material can be recycled by the steel industry. Independently of the origin of the samples, major mineralogical forms present in these wastes are Fe3O4, ZnO, ZnFe2O4 and PbOHCl. The proposed process consists of a hydrometallurgical treatment of wastes based on selective leaching of zinc and lead. Initially, a leaching is carried out utilizing a chelating agent, nitrilotriacetate anion (NTA3-), as the protonated form HNTA2-. Treatment of five EAFD samples for an hour at room temperature with a molar solution of reagent results in total leaching of the ZnO. In all cases the solubilized iron does not exceed 3 wt.%. The recovery of zinc and lead is performed by precipitation of metallic sulfides with a solution of Na2S4 sodium tetrasulfide 2M. These metallic sulfides can be used as metallurgical raw materials and the chelating reagent can be reused in the process after pH adjustment. The results of the normalized leaching test AFNOR X31-210 conducted on the leaching residues, shows that all the samples meet acceptance thresholds for hazardous wastes landfill. However, the residues contain a considerable amount of zinc as ZnFe2O4. The extraction of the zinc element requires the destruction of the ferrite structure. In this process, ZnFe2O4 is treated by FeCl3.6H2O. The reaction consists in a particle O2-/Cl- exchange allowing the recovery of zinc as ZnCl2 and iron as hematite Fe2O3. The separation of these products is accomplished by simple aqueous leaching. All of the zinc is extracted in a 8h treatment at 150 degrees C with a molar ratio FeCl3.6H2O/ZnFe2O4 equal to 10. Ultimate solid residues, which have been concentrated in iron, can be oriented towards the steel industry. PMID:11900917

  10. Investigation of techniques to improve continuous air monitors under conditions of high dust loading in environmental setting. 1998 annual progress report

    SciTech Connect

    Schery, S.D.; Wasiolek, P.T.; Rodgers, J.

    1998-06-01

    'Improvement in understanding of the deposition of ambient dust particles on ECAM (Environmental Continuous Air Monitor) filters, reduction of the alpha-particle interference of radon progeny and other radioactive aerosols in different particle size ranges on filters, and development of ECAM''s with increased sensitivity under dusty outdoor conditions. As of May 1, 1998 (1/2 year into the project) the research-prototype 30-cm pulsed ionization chamber (PIC) is assembled and operational with an alpha particle energy resolution of better than 45 keV for 5-MeV alpha particles. Measurements of spectral resolution for alpha particles from radon decay products have been made as a function of filter type and dust loading conditions. So far, a study of ten filter types has found that the best combination of resolution and throughput is obtained with 3.0 \\265m Millipore fluoropore and 1.0 \\265m Corning FNMB filters. Experiments with gypsum and Portland cement dust in the size range 1 to 20 \\265m indicate significant degradation in alpha particle resolution for dust loading above about 0.5 mg cm{sup -2}. Study of metalized films for possible use as a PIC window indicate a minimum broadening of 5-MeV alpha particle peaks from 43 (no film) to 301 keV (with film) for AVR film type B8 (0.20 mg cm{sup -2} polycarbonate). A modified ECAM sampling head, equipped with an optical microscopy system feeding data to a high resolution video data capture and logging instrument, was constructed. This system will enable time-lapse study of dust build-up on ECAM filters and formation of dendrite structures that can reduce alpha-particle resolution.'

  11. Human lead (Pb) exposure via dust from different land use settings of Pakistan: A case study from two urban mountainous cities.

    PubMed

    Eqani, Syed Ali Musstjab Akber Shah; Khalid, Ramsha; Bostan, Nazish; Saqib, Zafeer; Mohmand, Jawad; Rehan, Mohammad; Ali, Nadeem; Katsoyiannis, Ioannis A; Shen, Heqing

    2016-07-01

    The current study aims to determine the dust-borne lead (Pb) levels into outdoor dust, which were collected from the areas nearby the cities/districts of Islamabad and Swat in Pakistan. In general dust samples from all land use settings (industrial, urban and rural) showed significantly higher (p<0.05) Pb-levels (median, ppm) from Islamabad (110, 52, 24) than those of Swat district (75, 37, 21), respectively. Index of Geo-accumulation (Igeo values) indicated that industrial and urban areas of both sites were highly polluted due to severe anthropogenic influence, whereas the rural areas were in most parts unpolluted and where moderately polluted, this was mainly due to geological factors and short and/or long distance atmospheric deposition from surrounding polluted areas. According to the calculated chemical daily intake (mg/kg-day) values, dust ingestion is one of the major routes of human exposure for lead. Hazard Index (HI) values, calculated for both adult and children populations, were above unity in industrial and urban areas, indicating serious health risks especially to the children populations. PMID:27129063

  12. Comparison of IEUBK model predictions and actual blood lead values at a former battery recycling site.

    PubMed

    Lewandowski, T A; Forslund, B L

    1994-12-01

    This paper presents an evaluation of US EPA's integrated exposureuptake biokinetic model for lead (IEUBK model) using data obtained during emergency removal operations at a former lead-acid battery recycling plant and the surrounding community. Data employed in the study include soil lead and interior dust lead, air lead levels collected at the site perimeter, drinking water lead levels at the community water main and blood lead data collected from an annual blood lead monitoring programme conducted over a four year period during the remediation activities.Geometric mean soil and dust concentrations were found to be a better predictor of blood lead than arithmetic mean data. However, weight based dust lead data were believed to be an inappropriate measure of dust lead levels. Estimates of household dust lead concentrations based upon surface loading data (μg m(-2)) yielded blood lead predictions which were more consistent with data collected in the blood lead monitoring programme. PMID:24197215

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

    PubMed

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

    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. PMID:23712117

  14. Lead

    MedlinePlus

    ... Lead Share Facebook Twitter Google+ Pinterest Contact Us Lead Poisoning is Preventable If your home was built before ... of the RRP rule. Read more . Learn about Lead Poisoning Prevention Week . Report Uncertified Contractors and Environmental Violations ...

  15. Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Luong; Kim, Ho-Kyung

    2014-09-01

    In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor (K II) used to evaluate the fracture toughness (K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

  16. Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Luong; Kim, Ho-Kyung

    2014-11-01

    In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor ( K II) used to evaluate the fracture toughness ( K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

  17. Lead

    MedlinePlus

    ... obvious symptoms, it frequently goes unrecognized. CDC’s Childhood Lead Poisoning Prevention Program is committed to the Healthy People ... Lead Levels Information for Parents Tips for preventing lead poisoning About Us Overview of CDC’s Childhood Lead Poisoning ...

  18. In vitro bioaccessibility of lead in surface dust and implications for human exposure: A comparative study between industrial area and urban district.

    PubMed

    Bi, Xiangyang; Li, Zhonggen; Sun, Guangyi; Liu, Jinling; Han, Zhixuan

    2015-10-30

    In this study, ground surface dust samples from two contrasting areas, a former zinc smelting area in Guizhou Province and a common urban district in Wuhan city, Hubei Province, China, were assessed for in vitro Pb bioaccessibility using a physiologically based extraction test (PBET). Extremely elevated concentrations of Pb (220-6348 mg/kg) and other trace metals were observed in the zinc smelting area. While moderate high metal concentrations (79-1544 mg/kg of Pb) in the urban dusts were attributed to various urban activities, coal combustion and traffic emissions. Lead bioaccessibility in the stomach-phase varied from 17.6 to 76.1% and no significant difference was found between industrial and urban dust samples. Compared with the stomach-phase, Pb bioaccessibility in the more alkaline intestinal-phase was considerably lower (1.2-21.8%). A significantly negative correlation was found between dust Ca concentrations and Pb bioaccessibility in the intestinal-phase, suggesting that Ca plays an important role in reducing the bioaccessible Pb in the intestinal-phase. The estimated Pb exposure based on gastric bioaccessible Pb was 13.9 and 1.8 μg/kg day for children living in the industrial and urban areas, respectively, accounting for 85% and 41% of their corresponding total Pb exposure. PMID:25958267

  19. Detecting and assessing Saharan dust contribution to PM10 loads: A pilot study within the EU-Life+10 project DIAPASON

    NASA Astrophysics Data System (ADS)

    Gobbi, Gian Paolo; Barnaba, Francesca; Bolignano, Andrea; Costabile, Francesca; Di Liberto, Luca; Dionisi, Davide; Drewnick, Frank; Lucarelli, Franco; Manigrasso, Maurizio; Nava, Silvia; Sauvage, Laurent; Sozzi, Roberto; Struckmeier, Caroline; Wille, Holger

    2015-04-01

    The EC LIFE+2010 DIAPASON Project (Desert dust Impact on Air quality through model-Predictions and Advanced Sensors ObservatioNs, www.diapason-life.eu) intends to contribute new methodologies to assess the role of aerosol advections of Saharan dust to the local PM loads recorded in Europe. To this goal, automated Polarization Lidar-Ceilometers (PLCs) were prototyped within DIAPASON to certify the presence of Saharan dust plumes and support evaluating their mass loadings in the lowermost atmosphere. The whole process also involves operational dust forecasts, as well as satellite and in-situ observations. Demonstration of the Project is implemented in the pilot region of Rome (Central Italy) where three networked DIAPASON PLCs started, in October 2013 a year-round, 24h/day monitoring of the altitude-resolved aerosol backscatter and depolarization profiles. Two intensive observational periods (IOPs) involving chemical analysis and detailed physical characterization of aerosol samples have also been carried out in this year-long campaign, namely in Fall 2013 and Spring 2014. These allowed for an extensive interpretation of the PLC observations, highlighting important synergies between the PLC and the in situ data. The presentation will address capabilities of the employed PLCs, observations agreement with model forecasts of dust advections, retrievals of aerosol properties and methodologies developed to detect Saharan advections and to evaluate the relevant mass contribution to PM10. This latter task is intended to provide suggestions on possible improvements to the current EC Guidelines (2011) on this matter. In fact, specific Guidelines are delivered by the European Commission to provide the Member States a common method to asses the Saharan dust contribution to the currently legislated PM-related Air Quality metrics. The DIAPASON experience shows that improvements can be proposed to make the current EC Methodology more robust and flexible. The methodology DIAPASON

  20. Dynamic fracturing by successive coseismic loadings leads to pulverization in active fault zones

    NASA Astrophysics Data System (ADS)

    Aben, F. M.; Doan, M.-L.; Mitchell, T. M.; Toussaint, R.; Reuschlé, T.; Fondriest, M.; Gratier, J.-P.; Renard, F.

    2016-04-01

    Previous studies show that pulverized rocks observed along large faults can be created by single high-strain rate loadings in the laboratory, provided that the strain rate is higher than a certain pulverization threshold. Such loadings are analogous to large seismic events. In reality, pulverized rocks have been subject to numerous seismic events rather than one single event. Therefore, the effect of successive "milder" high-strain rate loadings on the pulverization threshold is investigated by applying loading conditions below the initial pulverization threshold. Single and successive loading experiments were performed on quartz-monzonite using a Split Hopkinson Pressure Bar apparatus. Damage-dependent petrophysical properties and elastic moduli were monitored by applying incremental strains. Furthermore, it is shown that the pulverization threshold can be reduced by successive "milder" dynamic loadings from strain rates of ~180 s-1 to ~90 s-1. To do so, it is imperative that the rock experiences dynamic fracturing during the successive loadings prior to pulverization. Combined with loading conditions during an earthquake rupture event, the following generalized fault damage zone structure perpendicular to the fault will develop: furthest from the fault plane, there is a stationary outer boundary that bounds a zone of dynamically fractured rocks. Closer to the fault, a pulverization boundary delimits a band of pulverized rock. Consecutive seismic events will cause progressive broadening of the band of pulverized rocks, eventually creating a wider damage zone observed in mature faults.

  1. Airborne soil dust and its importance in buffering of atmospheric acidity and critical load assessment, over the semi arid tract of northern India.

    NASA Astrophysics Data System (ADS)

    Sharma, Disha; Kulshrestha, Umesh

    Airborne soil dust and its importance in buffering of atmospheric acidity and critical load assessment, over the semi arid tract of northern India. The Critical Load approach alongwith integrated assessment models has been used in the European nations for policy formations to reduce acidic emissions. This unique approach was applied to assess the of vulnerability of natural systems to the present day atmospheric pollution scenario. The calculated values of critical loads of sulphur ( 225 - 275 eq/ha/yr) and nitrogen (298 - 303 eq/ha/yr), for the soil system in Delhi, were calculated with respect to Anjan grass, Hibiscus and Black siris. The present loads of sulphur (PL(S) = 26.40 eq/ha/yr) and nitrogen (PL(N) = 36.51 eq/ha/yr) were found to be much lower than their critical loads without posing any danger of atmospheric acidic deposition on the soil systems. The study indicated that the system is still protective due to high pH of soil. The nature of buffering capability of calcium derived from soil dust can be considered as a natural tool to combat acidification in the Indian region. The results showed that the pollution status in Delhi is still within the safe limits. However, at the pace at which the city is growing, it is likely that in coming decades, it may exceed these critical values. In order to set deposition limits and avoid adverse effects of acidic deposition this approach can be applied in India too. Such approach is very useful, not only in abating pollution but also in devising means of cost optimal emission abatement strategies.

  2. Lead Toxicity

    MedlinePlus

    ... homes. • Most people, especially children, who suffer from lead poisoning are exposed through lead-contaminated household dust or ... and six if they are at risk of lead poisoning (see: ). Who can I call to get more ...

  3. Identification of trace metal pollution in urban dust from kindergartens using magnetic, geochemical and lead isotopic analyses

    NASA Astrophysics Data System (ADS)

    Zhu, Zongmin; Sun, Guangyi; Bi, Xiangyang; Li, Zhonggen; Yu, Genhua

    2013-10-01

    In the present study, magnetic measurements were combined with geochemical analysis and stable Pb isotopic ratios to reveal the distribution and origination of trace metal pollutants in kindergarten dusts from a typical urban environment of Wuhan, central China. The geoaccumulation index (Igeo) of magnetic properties was more prominent than those of individual metals. The magnetic susceptibility (MS) and trace metals (Zn, Pb, and Cu) in this study together with published results from other Chinese cities formed a liner relationship, suggesting that metal contaminants in Chinese urban areas had similar MS to metal ratios, which could be used as an indicator for identification of pollution sources between Chinese cities and the other Asian cities. Stable Pb isotopic ratios (1.1125-1.1734 for 206Pb/207Pb and 2.4457-2.4679 for 208Pb/207Pb) in the urban dusts from Wuhan were characterized by higher 208Pb component in comparison with those from other Chinese cities. This result combined with principal component analysis (PCA) indicated that metal pollutants in the dusts were derived from industrial activities and coal combustion, whereas the traffic emissions were no longer a predominant pollution source in urban environment. Our study demonstrated that environmental magnetic methods could not only reveal the overall situation of trace metal contamination, but also prove evidence in the identification of pollution sources.

  4. Combined nutrient and macroalgae loads lead to response in seagrass indicator properties.

    PubMed

    Han, Qiuying; Soissons, Laura M; Bouma, Tjeerd J; van Katwijk, Marieke M; Liu, Dongyan

    2016-05-15

    Excess nutrients are potential factors that drive phase shifts from seagrasses to macroalgae. We carried out a manipulative field experiment to study the effects of macroalgae Ulva pertusa loading and nutrient addition to the water column on the nitrogen (N) and carbon (C) contents (i.e., fast indicators) as well as on the morphology and structure (i.e., slow indicators) of Zostera marina. Our results showed rapid impact of increased macroalgae and nutrient load on Z. marina C/N ratios. Also, macroalgae addition resulted in a trend of decreasing belowground biomass of seagrasses, and nutrient load significantly decreased above to belowground biomass ratio. Although some morphological/structural variables showed relatively fast responses, the effects of short-term disturbance by macroalgae and nutrients were less often significant than on physiological variables. Monitoring of seagrass physiological indicators may allow for early detection of eutrophication, which may initiate timely management interventions to avert seagrass loss. PMID:26975613

  5. Comparative response of lead-acid and nickel/iron batteries to pulsed and constant-current loads

    SciTech Connect

    DeLuca, W.H.; Tummillo, A.F.; Biwer, T.L.; Christianson, C.C.; Hornstra, F.; Yao, N.P.

    1983-01-01

    Improved lead-acid and nickel/iron batteries are currently being developed for use in electric vehicles. The response of these batteries to given discharge conditions differs due to the inherent characteristics of each system. The discharge capacity of the lead-acid system is reduced (>25%) at increased discharge rates and its internal resistance is a function of both depth-of-discharge (DOD) and discharge rate. However, open-circuit stand times (0.5 to 2.0 h) at DOD levels >50% reduce the internal resistance of the lead-acid system and provide a corresponding increase in its availability capacity. In comparison, the discharge capacity and internal resistance of the nickel/iron system are virtually independent of both discharge rate and open-circuit stand times during discharge. With pulsed-current loads, the available energy and power output of both battery systems are always less than those obtained with equivalent constant-current loads due to increased internal power losses. The nickel/iron system exhibits an internal inductance that is significantly greater than that for the lead-acid system thereby causing potentially damaging voltage transients. This paper describes the test procedures and system employed, presents the test data, and methods for predicting battery response, and discusses the results obtained.

  6. Tungsten dust impact on ITER-like plasma edge

    SciTech Connect

    Smirnov, R. D.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2015-01-12

    The impact of tungsten dust originating from divertor plates on the performance of edge plasma in ITER-like discharge is evaluated using computer modeling with the coupled dust-plasma transport code DUSTT-UEDGE. Different dust injection parameters, including dust size and mass injection rates, are surveyed. It is found that tungsten dust injection with rates as low as a few mg/s can lead to dangerously high tungsten impurity concentrations in the plasma core. Dust injections with rates of a few tens of mg/s are shown to have a significant effect on edge plasma parameters and dynamics in ITER scale tokamaks. The large impact of certain phenomena, such as dust shielding by an ablation cloud and the thermal force on tungsten ions, on dust/impurity transport in edge plasma and consequently on core tungsten contamination level is demonstrated. Lastly, it is also found that high-Z impurities provided by dust can induce macroscopic self-sustained plasma oscillations in plasma edge leading to large temporal variations of edge plasma parameters and heat load to divertor target plates.

  7. Tungsten dust impact on ITER-like plasma edge

    DOE PAGESBeta

    Smirnov, R. D.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2015-01-12

    The impact of tungsten dust originating from divertor plates on the performance of edge plasma in ITER-like discharge is evaluated using computer modeling with the coupled dust-plasma transport code DUSTT-UEDGE. Different dust injection parameters, including dust size and mass injection rates, are surveyed. It is found that tungsten dust injection with rates as low as a few mg/s can lead to dangerously high tungsten impurity concentrations in the plasma core. Dust injections with rates of a few tens of mg/s are shown to have a significant effect on edge plasma parameters and dynamics in ITER scale tokamaks. The large impactmore » of certain phenomena, such as dust shielding by an ablation cloud and the thermal force on tungsten ions, on dust/impurity transport in edge plasma and consequently on core tungsten contamination level is demonstrated. Lastly, it is also found that high-Z impurities provided by dust can induce macroscopic self-sustained plasma oscillations in plasma edge leading to large temporal variations of edge plasma parameters and heat load to divertor target plates.« less

  8. Tungsten dust impact on ITER-like plasma edge

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2015-01-01

    The impact of tungsten dust originating from divertor plates on the performance of edge plasma in ITER-like discharge is evaluated using computer modeling with the coupled dust-plasma transport code DUSTT-UEDGE. Different dust injection parameters, including dust size and mass injection rates, are surveyed. It is found that tungsten dust injection with rates as low as a few mg/s can lead to dangerously high tungsten impurity concentrations in the plasma core. Dust injections with rates of a few tens of mg/s are shown to have a significant effect on edge plasma parameters and dynamics in ITER scale tokamaks. The large impact of certain phenomena, such as dust shielding by an ablation cloud and the thermal force on tungsten ions, on dust/impurity transport in edge plasma and consequently on core tungsten contamination level is demonstrated. It is also found that high-Z impurities provided by dust can induce macroscopic self-sustained plasma oscillations in plasma edge leading to large temporal variations of edge plasma parameters and heat load to divertor target plates.

  9. Tungsten dust impact on ITER-like plasma edge

    SciTech Connect

    Smirnov, R. D. Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2015-01-15

    The impact of tungsten dust originating from divertor plates on the performance of edge plasma in ITER-like discharge is evaluated using computer modeling with the coupled dust-plasma transport code DUSTT-UEDGE. Different dust injection parameters, including dust size and mass injection rates, are surveyed. It is found that tungsten dust injection with rates as low as a few mg/s can lead to dangerously high tungsten impurity concentrations in the plasma core. Dust injections with rates of a few tens of mg/s are shown to have a significant effect on edge plasma parameters and dynamics in ITER scale tokamaks. The large impact of certain phenomena, such as dust shielding by an ablation cloud and the thermal force on tungsten ions, on dust/impurity transport in edge plasma and consequently on core tungsten contamination level is demonstrated. It is also found that high-Z impurities provided by dust can induce macroscopic self-sustained plasma oscillations in plasma edge leading to large temporal variations of edge plasma parameters and heat load to divertor target plates.

  10. Peeling Lead Paint Turns into Poisonous Dust. Guess Where It Ends Up? A Media Campaign to Prevent Childhood Lead Poisoning in New York City

    ERIC Educational Resources Information Center

    Greene, Danielle; Tehranifar, Parisa; DeMartini, Diana P.; Faciano, Andrew; Nagin, Deborah

    2015-01-01

    Successful public health media campaigns promote messages, increase awareness, engage the public, and encourage behavior change. Between 2004 and 2006, the Lead Poisoning Prevention Program of the New York City Department of Health and Mental Hygiene conducted a media campaign grounded in social learning theory and the social marketing model to…

  11. Peeling lead paint turns into poisonous dust. Guess where it ends up? A media campaign to prevent childhood lead poisoning in New York City.

    PubMed

    Greene, Danielle; Tehranifar, Parisa; DeMartini, Diana P; Faciano, Andrew; Nagin, Deborah

    2015-06-01

    Successful public health media campaigns promote messages, increase awareness, engage the public, and encourage behavior change. Between 2004 and 2006, the Lead Poisoning Prevention Program of the New York City Department of Health and Mental Hygiene conducted a media campaign grounded in social learning theory and the social marketing model to increase parents' awareness of childhood lead poisoning, ways to protect their children, and property owners' legal responsibility to fix peeling lead paint safely, and increase awareness of regulatory changes and encourage enforcement of New York City's Local Law 1 of 2004. Campaign materials were focus group tested and the campaign was refined annually. The campaign ran city-wide and in targeted high-risk neighborhoods. Neighborhoods and media venue (bus, train, kiosk, and store) changed annually, based on population risk factors and venue availability. Exposure to the campaign, campaign-related knowledge, and behavior were assessed using pre- and postcampaign street intercept surveys. Results showed that campaign reached the targeted population, and had an impact on knowledge of lead poisoning prevention measures as evidenced by increased knowledge of lead paint exposures sources in one year and increased knowledge of preventive behaviors in another year; these improvements were observed for both genders and most ethnic, primary language, educational attainment, and age groups in each year. Lessons learned indicate that well-targeted media campaigns, designed with audience participation, can reach parents through various venues, and improve key knowledge areas. Evaluation challenges faced include high levels of knowledge at baseline, competing media messages, and balancing between program needs and evaluation design. PMID:25558876

  12. Dust absorption over the ``Great Indian Desert'' inferred using ground-based and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Moorthy, K. Krishna; Babu, S. Suresh; Satheesh, S. K.; Srinivasan, J.; Dutt, C. B. S.

    2007-05-01

    Mineral dust is the single largest contributor of natural aerosols over land. Dust aerosols exhibit high variability in their radiative effects because their composition varies locally. This arises because of the regional distinctiveness of the soil characteristics as well as the accumulation of other aerosol species, such as black carbon, on dust while airborne. To accurately estimate the climate impact of dust, spatial and temporal distribution of its radiative properties are essential. However, this is poorly understood over many regions of the world, including the Indian region. In this paper, infrared (IR) radiance (10.5-12.5 μm) acquired from METEOSAT-5 satellite (˜5-km resolution) is used to retrieve dust aerosol characteristics over the "Great Indian Desert" and adjacent regions. The infrared radiance depression on account of the presence of dust in the atmosphere has been used as an index of dust load, called the Infrared Difference Dust Index (IDDI). Simultaneous, ground-based spectral optical depths estimated at visible and near-infrared wavelengths (using a multiwavelength solar radiometer) are used along with the IDDI to infer the dust absorption. The inferred single scattering albedo of dust was in the range of 0.88-0.94. We infer that dust over the Indian desert is of more absorbing nature (compared with African dust). Seasonally, the absorption is least in summer and most in winter. The large dust absorption leads to lower atmospheric warming of 0.7-1.2 K day-1.

  13. Comparative data on effects of leading pretreatments and enzyme loadings and formulations on sugar

    SciTech Connect

    Wyman, Charles; Balan, Venkatech; Dale, Bruce E.; Elander, Richard; Falls, Matthew; Hames, Bonnie; Holtzapple, Mark; Ladisch, Michael R.; Lee, Y. Y.; Mosier, Nathan; Pallapolu, Venkata R.; Shi, Jian; Warner, Ryan E.

    2011-06-16

    Dilute sulfuric acid (DA), sulfur dioxide (SO2), liquid hot water (LHW), soaking in aqueous ammonia (SAA), ammonia fiber expansion (AFEX), and lime pretreatments were applied to Alamo, Dacotah, and Shawnee switchgrass. Application of the same analytical methods and material balance approaches facil-itated meaningful comparisons of glucose and xylose yields from combined pretreatment and enzymatic hydrolysis. Use of a common supply of cellulase, beta-glucosidase, and xylanase also eased comparisons. All pretreatments enhanced sugar recovery from pretreatment and subsequent enzymatic hydrolysis substantially compared to untreated switchgrass. Adding beta-glucosidase was effective early in enzy-matic hydrolysis while cellobiose levels were high but had limited effect on longer term yields at the enzyme loadings applied. Adding xylanase improved yields most for higher pH pretreatments where more xylan was left in the solids. Harvest time had more impact on performance than switchgrass variety, and microscopy showed changes in different features could impact performance by different pretreatments.

  14. Long-term exposure to house dust mite leads to suppression of allergic airway disease despite persistent lung inflammation

    PubMed Central

    Bracken, Sonali J.; Adami, Alexander J.; Szczepanek, Steven M.; Ehsan, Mohsin; Natarajan, Prabitha; Guernsey, Linda A.; Shahriari, Neda; Rafti, Ektor; Matson, Adam P.; Schramm, Craig M.; Thrall, Roger S.

    2015-01-01

    Background Allergic asthma is a major cause of worldwide morbidity and results from inadequate immune regulation in response to innocuous, environmental antigens. The need exists to understand the mechanisms that promote non-reactivity to human-relevant allergens such as house dust mite (HDM) in order to develop curative therapies for asthma. The aim of our study was to compare the effects of short-, intermediate- and long-term HDM administration in a murine asthma model and determine the ability of long-term HDM exposure to suppress allergic inflammation. Methods C57BL/6 mice were intranasally instilled with HDM for short-term (2 weeks), intermediate-term (5 weeks) and long-term (11 weeks) periods to induce allergic airway disease (AAD). Severity of AAD was compared across all stages of the model via both immunologic and pulmonary parameters. Results Short- and intermediate-term HDM exposure stimulated development of AAD that included eosinophilia in the bronchoalveolar lavage fluid (BAL), pronounced airway hyper-reactivity (AHR), and evidence of lung inflammation. Long-term HDM exposure promoted suppression of AAD, with loss of BAL eosinophilia and AHR despite persistent mononuclear inflammation in the lungs. Suppression of AAD with long-term HDM exposure was associated with an increase in both Foxp3+ regulatory T cells and IL-10+ alveolar macrophages at the site of inflammation. Conclusions This model recapitulates key features of human asthma and may facilitate investigation into the mechanisms that promote immunological tolerance against clinically relevant aeroallergens. PMID:25924733

  15. Influenza A facilitates sensitization to house dust mite in infant mice leading to an asthma phenotype in adulthood.

    PubMed

    Al-Garawi, A; Fattouh, R; Botelho, F; Walker, T D; Goncharova, S; Moore, C-L; Mori, M; Erjefalt, J S; Chu, D K; Humbles, A A; Kolbeck, R; Stampfli, M R; O'Byrne, P M; Coyle, A J; Jordana, M

    2011-11-01

    The origins of allergic asthma, particularly in infancy, remain obscure. Respiratory viral infections and allergen sensitization in early life have been associated with asthma in young children. However, a causal link has not been established. We investigated whether an influenza A infection in early life alters immune responses to house dust mite (HDM) and promotes an asthmatic phenotype later in life. Neonatal (8-day-old) mice were infected with influenza virus and 7 days later, exposed to HDM for 3 weeks. Unlike adults, neonatal mice exposed to HDM exhibited negligible immune responsiveness to HDM, but not to influenza A. HDM responsiveness in adults was associated with distinct Ly6c+ CD11b+ inflammatory dendritic cell and CD8α+ plasmacytoid (pDC) populations that were absent in HDM-exposed infant mice, suggesting an important role in HDM-mediated inflammation. Remarkably, HDM hyporesponsiveness was overcome when exposure occurred concurrently with an acute influenza infection; young mice now displayed robust allergen-specific immunity, allergic inflammation, and lung remodeling. Remodeling persisted into early adulthood, even after prolonged discontinuation of allergen exposure and was associated with marked impairment of lung function. Our data demonstrate that allergen exposure coincident with acute viral infection in early life subverts constitutive allergen hyporesponsiveness and imprints an asthmatic phenotype in adulthood. PMID:21881572

  16. Behaviour of the steel T91 under uniaxial and multiaxial slow loading in contact with liquid lead

    NASA Astrophysics Data System (ADS)

    Hojná, Anna; Di Gabriele, Fosca; Klecka, Jakub; Burda, Jaroslav

    2015-11-01

    This work deals with the interaction between liquid lead and the ferritic-martensitic steel, T91. Mechanical properties of specimens loaded in contact with liquid lead were tested in laboratory and boundary conditions necessary to ascertain the sensitivity to Liquid Metal Embrittlement (LME) were studied. Three effects, temperature, deformation rate and surface treatment were selected to stimulate the LME initiation on smooth tensile specimens, then the notch effect was selected as an additional factor. Some specimens were pre-treated by application of a flux followed by dipping into liquid lead to simulate wetting. Slow strain rate tests (SSRT) of specimens immersed in liquid lead were performed applying strain rates from 10-2 to 10-8 1/s from 350° to 450 °C in test cell CALLISTO. Two types of tensile specimens were tested, smooth and notched. After tests, the fracture mode and the status of specimen surface was examined. Results of the specimens immersed in lead were compared with the results obtained in air. The most significant was the strain rate effect on the stress-strain curves of smooth specimens. Moreover, while no LME was observed for the smooth specimens, clear evidence of LME was observed for the notched specimens.

  17. DiMES Tests of W Leading Edge Power Loading in DIII-D

    NASA Astrophysics Data System (ADS)

    Nygren, R. E.; Watkins, J. G.; Rudakov, D. L.; Lasnier, C. J.; Pitts, R. A.; Stangeby, P. C.

    2015-11-01

    In a transient melt experiment in JET, the power to a ~1-mm-high leading edge on a W lamella in the bulk-W outer divertor was lower than expected from the geometry by factors of 5 and 2 for L-mode and H-mode discharges, respectively. We checked this surprising result in DIII-D with 3 W blocks (10 mm square) mounted radially side-by-side in DiMES with leading edges of 0.0, 0.3, 1.0 mm, single null L-mode plasmas, OSP just outside ``0.0'' block, limited scans (NBI+ECH), B-field incident at 1.5° or 2.5°, and viewed, as in JET, from above with 0.2mm/pixel resolution IRTV. Langmuir probes measured parallel power to the target. We compared probe and IR data with a detailed thermal model of the blocks and concluded provisionally that we did not reproduce the power deficit found in JET. Blurred IR images complicated fitting of temperature distributions from the thermal model. We plan an experiment with both L- and H-mode He plasmas before the APS meeting. Supported by US DOE under DE-AC04-94AL85000, 44500007360, DE-AC52-07NA27344, and DE-FC02-04ER54698.

  18. Bioaccessibility, release kinetics, and molecular speciation of arsenic and lead in geo-dusts from the Iron King Mine Federal Superfund site in Humboldt, Arizona.

    PubMed

    Menka, Nazune; Root, Rob; Chorover, Jon

    2014-01-01

    Mine tailings contain multiple toxic metal(loid)s that pose a threat to human health via inhalation and ingestion. The goals of this research include understanding the speciation and molecular environment of these toxic metal(loid)s (arsenic and lead) as well as the impacts particle size and residence time have on their bioaccessibilty in simulated gastric and lung fluid. Additionally, future work will include smaller size fractions (PM10 and PM2.5) of surface mine tailings, with the goal of increasing our understanding of multi-metal release from contaminated geo-dusts in simulated bio-fluids. This research is important to environmental human health risk assessment as it increases the accuracy of exposure estimations to toxic metal(loid)s. PMID:24552959

  19. Research, development and demonstration of advanced lead-acid batteries for utility load leveling

    NASA Astrophysics Data System (ADS)

    1983-08-01

    An advanced lead acid storage battery was developed to the preprototype cell and module design stage. Each module is equipped with a low cost tray, automatic watering system, and air-lift pumps for increased acid circulation in each cell. With the qualified alloy catastrophic positive grid corrosion will not limit cell cycle life. An accelerated shallow cycle regime at room ambient tested 60 cell designs for the active material shedding failure mode. It is found that an antishedding active material additive reduces positive active material shedding significantly and extend the cycle life of both the positive and the negative plate. Equations relating cell design to deep cycle life are developed from the factorial tests on the 60 cells.

  20. EVALUATION OF PORTABLE X-RAY FLUORESCENCE SPECTROMETER FOR MEASUREMENT OF LEAD IN PAINT, SOIL AND DUST

    EPA Science Inventory

    Three widely used commercially available portable X-ray fluorescence spectrometers were evaluated for precision and accuracy of measurement of lead in paint. ncluded were two direct reading instruments and one spectrum analyzer. est materials were prepared by spiking oil-based an...

  1. Microwave emission from lead zirconate titanate induced by impulsive mechanical load

    NASA Astrophysics Data System (ADS)

    Aman, A.; Majcherek, S.; Hirsch, S.; Schmidt, B.

    2015-10-01

    This paper focuses on microwave emission from Lead zirconate titanate Pb [ZrxTi1-x] O3 (PZT) induced by mechanical stressing. The mechanical stress was initiated by impact of a sharp tungsten indenter on the upper surface of PZT ceramic. The sequences of microwave and current impulses, which flew from indenter to electric ground, were detected simultaneously. The voltage between the upper and lower surface of ceramic was measured to obtain the behavior of mechanical force acting on ceramic during the impact. It was found that the amplitude, form, and frequency of measured microwave impulses were different by compression and restitution phase of impact. Two different mechanisms of electron emission, responsible for microwave impulse generation, were proposed based on the dissimilar impulse behavior. The field emission from tungsten indenter is dominant during compression, whereas ferroemission dominates during restitution phase. Indeed, it was observed that the direction of the current flow, i.e., sign of current impulses is changed by transitions from compression to restitution phase of impact. The observed dissimilar behavior of microwave impulses, caused by increasing and decreasing applied force, can be used to calculate the contact time and behavior of mechanical force during mechanical impact on ceramic surface. It is shown that the generation of microwave impulses exhibits high reproducibility, impulse intensity, a low damping factor, and high mechanical failure resistance. Based on these microwave emission properties of PZT, the development of new type of stress sensor with spatial resolution of few microns becomes possible.

  2. Microwave emission from lead zirconate titanate induced by impulsive mechanical load

    SciTech Connect

    Aman, A.; Majcherek, S.; Hirsch, S.; Schmidt, B.

    2015-10-28

    This paper focuses on microwave emission from Lead zirconate titanate Pb [Zr{sub x}Ti{sub 1−x}] O{sub 3} (PZT) induced by mechanical stressing. The mechanical stress was initiated by impact of a sharp tungsten indenter on the upper surface of PZT ceramic. The sequences of microwave and current impulses, which flew from indenter to electric ground, were detected simultaneously. The voltage between the upper and lower surface of ceramic was measured to obtain the behavior of mechanical force acting on ceramic during the impact. It was found that the amplitude, form, and frequency of measured microwave impulses were different by compression and restitution phase of impact. Two different mechanisms of electron emission, responsible for microwave impulse generation, were proposed based on the dissimilar impulse behavior. The field emission from tungsten indenter is dominant during compression, whereas ferroemission dominates during restitution phase. Indeed, it was observed that the direction of the current flow, i.e., sign of current impulses is changed by transitions from compression to restitution phase of impact. The observed dissimilar behavior of microwave impulses, caused by increasing and decreasing applied force, can be used to calculate the contact time and behavior of mechanical force during mechanical impact on ceramic surface. It is shown that the generation of microwave impulses exhibits high reproducibility, impulse intensity, a low damping factor, and high mechanical failure resistance. Based on these microwave emission properties of PZT, the development of new type of stress sensor with spatial resolution of few microns becomes possible.

  3. A consideration of the effects of dust aerosol and surface dust on Snowball Earth deglaciation

    NASA Astrophysics Data System (ADS)

    Abbot, D. S.; Halevy, I.; Pierrehumbert, R.

    2009-12-01

    Most previous global climate model simulations could only produce the termination of Snowball Earth episodes at CO2 partial pressures of several tenths of a bar, which is roughly an order of magnitude higher than recent estimates of CO2 levels during and shortly after Snowball events. These simulations have neglected the impact of surface dust on the ice albedo and dust aerosols on radiative transfer, which is an assumption of potentially grave importance. We argue, using the Dust Entrainment and Deposition (DEAD) box model driven by GCM results, that increased dust source and decreased dust sink during Snowball Earth events would have combined to produce atmospheric dust aerosol concentrations one to two orders of magnitude higher than today. We perform calculations using NCAR's Single Column Atmospheric Model (SCAM), a radiative-convective model with sophisticated aerosol, cloud, and radiative parameterizations, that show that when the surface albedo is high, increases of roughly one order of magnitude in dust aerosol loading can produce several times more surface warming than an increase in pCO2 from 10^-4 to 10^-1 bar. Additionally, we argue that over the lifetime of a Snowball event, ice dynamics should lead to the development of a layer of continental and volcanic dust at the ice surface in the tropics that would significantly lower the tropical surface albedo and encourage deglaciation. We test this idea by running the FOAM and CAM GCMs with an added tropical dust layer of different sizes and albedos and find that the tropical dust layer causes Snowball deglaciation at pCO2 values consistent with observations in a reasonable regime of these parameters. Therefore we conclude that including dust processes in simulations can reconcile the CO2 levels required for Snowball termination in climate models with observations. Surface air temperature as a function of the surface albedo, pCO2 and dust loading. The dust profile is either the modern tropical average

  4. Identification of lead sources in residential environments: Sydney Australia.

    PubMed

    Laidlaw, M A S; Zahran, S; Pingitore, N; Clague, J; Devlin, G; Taylor, M P

    2014-01-01

    Interior and exterior dust, soil and paint were analysed at five brick urban Sydney homes over 15 months to evaluate temporal variations and discriminate sources of lead (Pb) exposure. Exterior dust gauge Pb loading rates (μg/m(2)/28 days), interior vacuum dust Pb concentrations (mg/kg) and interior petri-dish Pb loading rates (μg/m(2)/28 days), were correlated positively with soil Pb concentrations. Exterior dust gauge Pb loading rates and interior vacuum dust Pb concentrations peaked in the summer. Lead isotope and Pb speciation (XAS) were analysed in soil and vacuum dust samples from three of the five houses that had elevated Pb concentrations. Results show that the source of interior dust lead was primarily from soil in two of the three houses and from soil and Pb paint in the third home. IEUBK child blood Pb modelling predicts that children's blood Pb levels could exceed 5 μg/dL in two of the five houses. PMID:24071634

  5. Comparison of a wipe method with and without a rinse to recover wall losses in closed face 37-mm cassettes used for sampling lead dust particulates

    PubMed Central

    Ceballos, Diana; King, Bradley; Beaucham, Catherine; Brueck, Scott E.

    2015-01-01

    Closed-face 37-millimeter (mm) polystyrene cassettes are often used for exposure monitoring of metal particulates. Several methods have been proposed to account for the wall loss in air sampling cassettes, including rinsing, wiping, within-cassette dissolution, and an internal capsule fused to the filter that could be digested with the filter. Until internal capsules replace filters, other methods for assessing wall losses may be considered. To determine if rinsing and wiping or wiping alone is adequate to determine wall losses on cassettes, we collected 54 full-shift area air samples at a battery recycling facility. We collected six replicate samples at three locations within the facility for 3 consecutive days. The wall losses of three replicate cassettes from each day-location were analyzed following a rinse and two consecutive wipes. The wall losses of the other three replicates from each day-location were analyzed following two consecutive wipes only. Mixed-cellulose ester membrane filter, rinse, and wipes were analyzed separately following NIOSH Method 7303. We found an average of 29% (range: 8%–54%) recovered lead from the cassette walls for all samples. We also found that rinsing prior to wiping the interior cassette walls did not substantially improve recovery of wall losses compared to wiping alone. A rinse plus one wipe recovered on average 23% (range: 13%–33%) of the lead, while one wipe alone recovered on average 21% (range: 16%–22%). Similarly we determined that a second wipe did not provide substantial additional recovery of lead (average: 4%, range: 0.4%–19%) compared to the first wipe disregarding the rinse (average: 18%, range: 4%–39%). We concluded that when an internal capsule is not used, wall losses of lead dust in air sampling cassettes can be adequately recovered by wiping the internal wall surfaces of the cassette with a single wipe. PMID:26125330

  6. Concentration of lead, cadmium, and iron in sediment dust and total suspended particles before and after initialisation of integral production in iron and steel work plant Zenica.

    PubMed

    Prcanović, Halim; Duraković, Mirnes; Beganović, Sanela

    2012-06-01

    Poor air quality is a common fact for all areas with base industry. The city of Zenica was once the metallurgical centre of Ex-Yugoslavia and is therefore highly polluted at present. Air pollution peaked in 1987 when average concentration of pollutants was extremely high (daily average concentration of SO(2) was 1800 μg m(-3)). With the beginning of the war in 1992, integral production in the steel work plant was shut down, to be re-launched in 2008. Limit values for iron do not exist, but iron has been monitored in Zenica for the past 28 years because of the presence of steel works. Concentrations of cadmium and lead have also been measured because they are very much present in polluted areas with steel works. The concentration of mentioned elements in air deposit and total suspended particles before and after integral production in the steel work plant was re-launched is the subject of this paper. Total suspended particles were measured in two locations using German standard VDI 2463 Blatt 4. Sediment dust was measured in nine locations using Bergerhoff method. The concentration of iron, lead, and cadmium was performed in the chemical laboratory of the Metallurgical Institute "Kemal Kapetanović" Zenica using standard methods. Higher concentrations of these parameters during the period of integral production clearly point to the impact of steel works on Zenica valley. PMID:22728800

  7. Deformation in lead zirconate titanate ceramics under large signal electric field loading measured by digital image correlation

    NASA Astrophysics Data System (ADS)

    Chen, Di; Kamlah, Marc

    2015-11-01

    Digital image correlation, a noncontact and nondestructive method, was employed to monitor the deformation of lead zirconate titanate piezoelectric ceramics. This method is based on imaging a speckle pattern on the specimen surface during the test and subsequently correlating each image of the deformed pattern to that in the reference state. In our work, both longitudinal and transverse strains were calculated from imaging a bulk sample under a ±2 kV/mm electric field. Compared with linear variable displacement transducer data, the results from this correlation method were validated. At the same time, based on this optical technique, different strain-electric field butterfly loops can be drawn from correspondingly selected regions of interest. Combined with contour plots of strain on the surface of the sample, the deformation of bulk ceramic sample under uniaxial electric field loading without any mechanical constraints is proven to be highly homogenous under macro-observing scale.

  8. Performance predictions of mature experimental constructed wetlands which treat urban water receiving high loads of lead and copper.

    PubMed

    Scholz, Miklas

    2003-03-01

    The treatment efficiencies of vertical-flow wetland filters containing macrophytes and granular media of different adsorption capacities were investigated. Different concentrations of lead and copper sulphate were added to urban stream inflow water in order to simulate pre-treated (pH adjustment assumed) mine wastewater. After 1 year of operation, the metal mass load rate was increased by a factor of approximately 4.6. No breakthrough of metals was recorded. The use of macrophytes and adsorption media did not enhance heavy metal reduction significantly after 13 months of operation. A correlation analysis indicated strong positive correlations between conductivity on one side and other variables including temperature, total solids, dissolved oxygen and the redox potential on the other side. Some expensive or time-consuming variables (e.g., biochemical oxygen demand) can be predicted with less expensive ones (e.g., dissolved oxygen and temperature). The associated absolute mean errors were <10%. PMID:12598191

  9. Aerosol Properties Changes of Northeast Asia due to a Severe Dust Storm in April 2014

    NASA Astrophysics Data System (ADS)

    Fang, Li; Wang, Shupeng; Yu, Tao; Gu, Xingfa; Zhang, Xingying; Wang, Weihe; Ren, Suling

    2016-04-01

    This study focuses on analyzing the aerosol properties changes due to the dust storm named as "China's Great Wall of Dust" oriented from Taklimakan desert in April, 2014. Dust identification IDDI (Infrared Difference Dust Index) images from FY-2E and true color composite images from FY-3C MERSI (Medium Resolution Spectral Imager) show the breakout and transport of the dust storm.From 4-day forward air mass trajectories, the dusty air masses were mostly transported within the lower boundary layer(<3km) over the Northwest China on April 23rd and April 24th, however they were progressively increasing in altitude to above 5km above the surface when they reached the central part of north China region (32°N-42°N; 105°E-123°E). 3-hourly data records at surface stations suggest that anticyclonic circulation occupying southern Xinjiang basin and cyclonic circulation maintaining in Mongolia formed the typical Synoptic condition which leaded to the strong dust storm. Aerosol Index (AI) results of TOU (Total Ozone Unit) aboard FY-3B are first developed and used in studying the affected areas due to the dust storm. The retrieved aerosol indexes show sensitivity to the dust particles. The dust affected areas agree with the synoptic meteorological condition analysis, which prove the synoptic meteorological condition is the main reason for the break out and transport of the dust storm. Anomalies of the average MODIS (Moderate Resolution Imaging Spectroradiometer) AOD (Aerosol Optical Depth) distributions over Northeast Asia during the dust storm to the average of that in April between 2010-2014 show high aerosol loading due to the dust storm. Compared with the 5-year average AOD in April, aerosol loading during this dust storm was much higher, with AOD values at 550nm up to 2.9 observed over the northwest China.The dust storm also brought different change in the aerosol microphysical properties between Beijing and Dalanzadgad. Aerosol Robotic Network (AERONET) retrievals

  10. Ionic liquid coated carbon nanospheres as a new adsorbent for fast solid phase extraction of trace copper and lead from sea water, wastewater, street dust and spice samples.

    PubMed

    Tokalıoğlu, Şerife; Yavuz, Emre; Şahan, Halil; Çolak, Süleyman Gökhan; Ocakoğlu, Kasım; Kaçer, Mehmet; Patat, Şaban

    2016-10-01

    In this study a new adsorbent, ionic liquid (1,8-naphthalene monoimide bearing imidazolium salt) coated carbon nanospheres, was synthesized for the first time and it was used for the solid phase extraction of copper and lead from various samples prior to determination by flame atomic absorption spectrometry. The ionic liquid, carbon nanospheres and ionic liquid coated carbon nanospheres were characterized by using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, (1)H NMR and (13)C NMR, Brunauer, Emmett and Teller surface area and zeta potential measurements. Various parameters for method optimization such as pH, adsorption and elution contact times, eluent volume, type and concentration, centrifuge time, sample volume, adsorption capacity and possible interfering ion effects were tested. The optimum pH was 6. The preconcentration factor, detection limits, adsorption capacity and precision (as RSD%) of the method were found to be 300-fold, 0.30µgL(-1), 60mgg(-1) and 1.1% for copper and 300-fold, 1.76µgL(-1); 50.3mgg(-1) and 2.2%, for lead, respectively. The effect of contact time results showed that copper and lead were adsorbed and desorbed from the adsorbent without vortexing. The equilibrium between analyte and adsorbent is reached very quickly. The method was rather selective for matrix ions in high concentrations. The accuracy of the developed method was confirmed by analyzing certified reference materials (LGC6016 Estuarine Water, Reference Material 8704 Buffalo River Sediment, and BCR-482 Lichen) and by spiking sea water, wastewater, street dust and spice samples. PMID:27474302

  11. DUST FORMATION IN MACRONOVAE

    SciTech Connect

    Takami, Hajime; Ioka, Kunihito; Nozawa, Takaya E-mail: kunihito.ioka@kek.jp

    2014-07-01

    We examine dust formation in macronovae (as known as kilonovae), which are the bright ejecta of neutron star binary mergers and one of the leading sites of r-process nucleosynthesis. In light of information about the first macronova candidate associated with GRB 130603B, we find that dust grains of r-process elements have difficulty forming because of the low number density of the r-process atoms, while carbon or elements lighter than iron can condense into dust if they are abundant. Dust grains absorb emission from ejecta with an opacity even greater than that of the r-process elements, and re-emit photons at infrared wavelengths. Such dust emission can potentially account for macronovae without r-process nucleosynthesis as an alternative model. This dust scenario predicts a spectrum with fewer features than the r-process model and day-scale optical-to-ultraviolet emission.

  12. Vacuum Head Removes Sanding Dust

    NASA Technical Reports Server (NTRS)

    Bengle, C. G.; Holt, J. W.

    1982-01-01

    Vacuum sander prevents sanding dust from entering a work area, since dust particles are drawn off as quickly as they are produced. Tool is useful where dust presents health hazards, interferes with such processes as semiconductor manufacture, or could destroy wet paint or varnish finishes. Could be used to sand such materials as lead paint.

  13. Magnetic susceptibility of dust-loaded leaves as a proxy of traffic-related heavy metal pollution in Kathmandu city, Nepal

    NASA Astrophysics Data System (ADS)

    Gautam, Pitambar; Blaha, Ulrich; Appel, Erwin

    Dust-loaded tree leaves from Kathmandu have been analyzed for magnetic susceptibility ( χ) and heavy metal (HM) contents. For 221 samples of leaves of cypress (mainly Cupressus corneyana), silky oak ( Grevillea robusta) and bottlebrush ( Callistemon lanceolatus), χ has a range of (0.01-54)×10 -8 m 3 kg -1 with a median of about 10.0×10 -8 m 3 kg -1. Trees situated close to the busy road intersections, near the main bus station and sectors of roads with steep slope yield elevated susceptibility. Chemical analysis of 20 samples of varying susceptibility by atomic absorption spectrometry yields the following maximum HM contents: Fe (1.3 wt%), Mn (281.9 ppm), Zn (195.2 ppm), Cu (41.5 ppm), Pb (38.4 ppm), Ni (8.1 ppm), Cr (6.4 ppm), Co (4.1 ppm) and Cd (1.2 ppm). The logarithmic susceptibility on dry mass basis ( χ) shows significant linear relationship with HM contents: Pearson's correlation coefficient r>0.8 with Zn, Fe, Cr; r>0.7 with Mn, Cu; r>0.6 with Pb, Ni. Magnetic phases are of soft (magnetite/maghemite) and hard (hematite) coercivities. Microscopy of magnetic extracts reveals spherules (mostly of 2-20 μm diameter) originated from vehicle exhausts through the combustion process as well as crystalline grains of lithogenic origin. The dust accumulation in leaves took place mainly after monsoon (beginning of October 2001) till the sampling period (first half of February 2002). Despite the dependence of susceptibility and HM contents on a variety of spatial and temporal factors (amount of particulate matter (PM), efficiency of deposition/removal of PM by wind, precipitation, birds etc.), a significant correlation of susceptibility to HM implies that the former serves as an effective proxy of metallic pollution. Hence, susceptibility-based bio-monitoring technique is recommended as an economic and rapid tool for assessment of environmental pollution in urban areas like Kathmandu.

  14. Annual trace-metal load estimates and flow-weighted concentrations of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, 1999-2004

    USGS Publications Warehouse

    Donato, Mary M.

    2006-01-01

    Streamflow and trace-metal concentration data collected at 10 locations in the Spokane River basin of northern Idaho and eastern Washington during 1999-2004 were used as input for the U.S. Geological Survey software, LOADEST, to estimate annual loads and mean flow-weighted concentrations of total and dissolved cadmium, lead, and zinc. Cadmium composed less than 1 percent of the total metal load at all stations; lead constituted from 6 to 42 percent of the total load at stations upstream from Coeur d'Alene Lake and from 2 to 4 percent at stations downstream of the lake. Zinc composed more than 90 percent of the total metal load at 6 of the 10 stations examined in this study. Trace-metal loads were lowest at the station on Pine Creek below Amy Gulch, where the mean annual total cadmium load for 1999-2004 was 39 kilograms per year (kg/yr), the mean estimated total lead load was about 1,700 kg/yr, and the mean annual total zinc load was 14,000 kg/yr. The trace-metal loads at stations on North Fork Coeur d'Alene River at Enaville, Ninemile Creek, and Canyon Creek also were relatively low. Trace-metal loads were highest at the station at Coeur d'Alene River near Harrison. The mean annual total cadmium load was 3,400 kg/yr, the mean total lead load was 240,000 kg/yr, and the mean total zinc load was 510,000 kg/yr for 1999-2004. Trace-metal loads at the station at South Fork Coeur d'Alene River near Pinehurst and the three stations on the Spokane River downstream of Coeur d'Alene Lake also were relatively high. Differences in metal loads, particularly lead, between stations upstream and downstream of Coeur d'Alene Lake likely are due to trapping and retention of metals in lakebed sediments. LOADEST software was used to estimate loads for water years 1999-2001 for many of the same sites discussed in this report. Overall, results from this study and those from a previous study are in good agreement. Observed differences between the two studies are attributable to streamflow

  15. The Martian Dust Cycle: Observations and Modeling

    NASA Technical Reports Server (NTRS)

    Kahre, Melinda A.

    2013-01-01

    The dust cycle is critically important for Mars' current climate system. Suspended atmospheric dust affects the radiative balance of the atmosphere, and thus greatly influences the thermal and dynamical state of the atmosphere. Evidence for the presence of dust in the Martian atmosphere can be traced back to yellow clouds telescopically observed as early as the early 19th century. The Mariner 9 orbiter arrived at Mars in November of 1971 to find a planet completely enshrouded in airborne dust. Since that time, the exchange of dust between the planet's surface and atmosphere and the role of airborne dust on Mars' weather and climate has been studied using observations and numerical models. The goal of this talk is to give an overview of the observations and to discuss the successes and challenges associated with modeling the dust cycle. Dust raising events on Mars range in size from meters to hundreds of kilometers. During some years, regional storms merge to produce hemispheric or planet encircling dust clouds that obscure the surface and raise atmospheric temperatures by tens of kelvin. The interannual variability of planet encircling dust storms is poorly understood. 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. 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 are generally observed: one peak occurs before northern winter solstice and one peak occurs after northern winter solstice. Numerical modeling studies attempting to interactively simulate the Martian dust cycle with general circulation models (GCMs) include the lifting, transport, and sedimentation of radiatively active dust. Two dust lifting processes are commonly represented in

  16. Dust-induced radiative feedbacks in north China: A dust storm episode modeling study using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Liu, Lixia; Huang, Xin; Ding, Aijun; Fu, Congbin

    2016-03-01

    Radiative forcing of dust aerosol and the radiative feedbacks on the planetary boundary layer (PBL) in North China during a typical Asian dust storm in the early April of 2011 was investigated by an online coupled meteorology-chemistry-aerosol model WRF-Chem. Dust-induced daily mean radiative forcing (RF) at the ground surface and in the atmosphere were estimated to be -21.1 W m-2 and 12.7 W m-2, respectively, over Gobi desert, and -13.1 W m-2 and 4.8 W m-2, respectively, in downwind region over the North China Plain (NCP). Comparatively, radiative perturbation on short-wave radiation was approximately twice that on long-wave radiation in magnitude. In the daytime, when solar radiation dominated, the surface cooling and atmospheric heating due to dust increased PBL stability, leading to reductions of PBL height (PBLH) about 90 m and decreases in wind speed up to 0.4 m s-1. On the contrary, the radiative forcing in terrestrial radiation caused an opposite response at night, especially in the downwind region. Although dust emission was repressed by weakened wind speed during daytime, the elevated PBLH along with larger deflation at night lifted more dust particles to higher altitude (by up to 75 m in average), which prolonged dust residence time in the atmosphere and further intensified dust loading in downwind areas. Taking dust radiative feedbacks into consideration notably narrowed gaps between model-predicted air temperature vertical profiles with corresponding observations, suggesting a significant importance of dust-radiation interaction in PBL meteorology during dust storms.

  17. Load and stability measurements on a soft-inplane rotor system incorporating elastomeric lead-lag dampers

    NASA Technical Reports Server (NTRS)

    Weller, W. H.

    1977-01-01

    An experimental investigation was conducted of the dynamic response and inplane stability associated with a new soft-inplane helicopter rotor. The unique feature of this rotor was the use of an internal elastomeric damper to restrain the blade inplane motion about the lead-lag hinge. The properties of the elastomer were selected to provide both a nominal first inplane frequency ratio of 0.65 and sufficient damping to eliminate the need for additional external damping sources to prevent ground resonance on a typical fuselage structure. For this investigation a 1/5-scale aeroelastic model was used to represent the rotor. The four-blade model had a diameter of 3.05 m (10 ft) and a solidity of 0.103. The first out-of-plane frequency ratio was 1.06. The model was tested in hover and in forward flight up to an advance ratio of 0.45. At each forward speed the rotor lift was varied up to simulated maneuver conditions. The measured rotor loads and response were within acceptable limits, and no adverse response qualities were observed. Moderate out-of-plane hub moments were measured, even for zero lift, to indicate the beneficial control power available for this design. Blade inplane stability testing indicated that the rotor system damping remained at moderate levels throughout the operating envelope.

  18. Concentrations and loads of cadmium, lead, zinc, and nutrients measured during the 1999 water year within the Spokane River basin, Idaho and Washington

    USGS Publications Warehouse

    Woods, P.F.

    2001-01-01

    the network was to quantify the absolute and relative magnitude of hydrologic, trace-element, and nutrient loads transported by numerous stream reaches within the Spokane River Basin. Of the 29 water-quality stations in the network, 19 were in the Coeur d?Alene River Basin, 2 were in the St. Joe River Basin, and the remaining 8 were on the Spokane River downstream from Coeur d'Alene Lake. All stations were sampled for whole-water recoverable and dissolved concentrations of cadmium, lead, and zinc. Nitrogen and phosphorus concentrations were sampled at nine stations to determine loads of nutrients into and out of Coeur d'Alene Lake and transported down the Spokane River into the Columbia River. Mean daily discharge during the 1999 water year was about 120 percent of the long-term average. Trace-element loads to the Columbia River were calculated for the basin's terminal station, Spokane River at Long Lake. For whole-water recoverable cadmium, 2,110 pounds, 92 percent of which was dissolved, was delivered to the Columbia River. The Columbia River received 25,000 pounds of whole-water recoverable lead, 29 percent of which was dissolved, from the Spokane River Basin. The largest trace-element load delivered to the Columbia River by the Spokane River was 764,000 pounds of whole-water recoverable zinc, 76 percent of which was dissolved. The primary source of trace-element loads in the Spokane River Basin was the Coeur d'Alene River Basin. The South Fork Coeur d'Alene River was the largest source of dissolved and wholewater recoverable loads of cadmium and zinc. In contrast, the main stem of the Coeur d'Alene River was the largest source of dissolved and wholewater recoverable loads of lead. Within the South Fork, substantial increases in dissolved loads of cadmium, lead, and zinc were detected in excess of those measured by the monitoring network stations upstream from the terminal station, South Fork Coeur d'Alene River near Pinehurst. Much of the added load was

  19. Laminar Dust Flames: A Program of Microgravity and Ground Based Studies at McGill

    NASA Technical Reports Server (NTRS)

    Goroshin, Sam; Lee, John

    1999-01-01

    Fundamental knowledge of heterogeneous combustion mechanisms is required to improve utilization of solid fuels (e.g. coal), safe handling of combustible dusts in industry, and solid propulsion systems. The objective of the McGill University research program on dust combustion is to obtain a reliable set of data on basic combustion parameters for dust suspensions (i.e. laminar burning velocity, flame structure, quenching distance, flammability limits, etc.) over a range of particle sizes, dust concentrations, and types of fuel. This set of data then permits theoretical models to be validated and, when necessary, new models to be developed to describe the detailed reaction mechanisms and transport processes. Microgravity is essential to the generation of a uniform dust suspension of arbitrary particle size and concentration. When particles with a characteristic size on the order of tens of microns are suspended, they rapidly settle in a gravitational field. To maintain a particulate in suspension for time duration adequate to carry out combustion experiments invariably requires continuous convective flow in excess of the gravitational settling velocity (which is comparable with and can even exceed the dust laminar burning velocity). This makes the experiments turbulent in nature and thus renders it impossible to study laminar dust flames. Even for small particle sizes on the order of microns, a stable laminar dust flow can be maintained only for relatively low dust concentrations at normal gravity conditions. High dust loading leads to gravitational instability of the dust cloud and to the formation of recirculation cells in the dust suspension in a confined volume, or to the rapid sedimentation of the dense dust cloud, as a whole, in an unconfined volume. Many important solid fuels such as carbon and boron also have low laminar flame speeds (of the order of several centimeters per second). Convection that occurs in combustion products due to buoyancy disrupts the

  20. Temperature and dust profiles in Martian dust storm conditions retrieved from Mars Climate Sounder measurements

    NASA Astrophysics Data System (ADS)

    Kleinboehl, A.; Kass, D. M.; Schofield, J. T.; McCleese, D. J.

    2013-12-01

    Mars Climate Sounder (MCS) is a mid- and far-infrared thermal emission radiometer on board the Mars Reconnaissance Orbiter. It measures radiances in limb and nadir/on-planet geometry from which vertical profiles of atmospheric temperature, water vapor, dust and condensates can be retrieved in an altitude range from 0 to 80 km and with a vertical resolution of ~5 km. Due to the limb geometry used as the MCS primary observation mode, retrievals in conditions with high aerosol loading are challenging. We have developed several modifications to the MCS retrieval algorithm that will facilitate profile retrievals in high-dust conditions. Key modifications include a retrieval option that uses a surface pressure climatology if a pressure retrieval is not possible in high dust conditions, an extension of aerosol retrievals to higher altitudes, and a correction to the surface temperature climatology. In conditions of a global dust storm, surface temperatures tend to be lower compared to standard conditions. Taking this into account using an adaptive value based on atmospheric opacity leads to improved fits to the radiances measured by MCS and improves the retrieval success rate. We present first results of these improved retrievals during the global dust storm in 2007. Based on the limb opacities observed during the storm, retrievals are typically possible above ~30 km altitude. Temperatures around 240 K are observed in the middle atmosphere at mid- and high southern latitudes after the onset of the storm. Dust appears to be nearly homogeneously mixed at lower altitudes. Significant dust opacities are detected at least up to 70 km altitude. During much of the storm, in particular at higher altitudes, the retrieved dust profiles closely resemble a Conrath-profile.

  1. Drought-induced enrichment of soil nitrogen leads to record high nitrate loading to agricultural river networks (Invited)

    NASA Astrophysics Data System (ADS)

    Burgin, A. J.; Loecke, T. D.; Davis, C.; Ward, A. S.; St. Clair, M.; Riveros-Iregui, D.; Thomas, S. A.

    2013-12-01

    Nitrogen (N) fertilization is a cornerstone of modern agriculture, but the practice also leads to eutrophication, hypoxia, and harmful algal blooms in both inland and coastal waters. Several studies identify Iowa, Illinois and Indiana as major source areas of N discharged by the Mississippi River to the Gulf of Mexico where large-scale hypoxia develops annually. Continental-scale management of nitrogen requires a comprehensive understanding of watershed-specific hydrologic dynamics and their consequences for nitrate flushing from agricultural landscapes, as well as quantification of fertilizer export in relation to interannual climate variability. This study addresses the following questions: (1) How do climate and precipitation patterns control the magnitude and timing of nitrate flushing from agricultural landscapes; and (2) How does the stream nitrate pulse change in relation to position within the stream network? We instrumented five streams of varying order (1st to 4th) and watershed size (5 ha to 3240000 ha) with real-time nitrate sensors. We combined this information with 15 existing USGS stations, located throughout the Iowa-Cedar River basin (Iowa, USA). We then coupled 15-min nitrate measurements at selected streams with seasonal (May, July, September) synoptic sampling at 100+ locations through the basin. We demonstrate that drought-induced accumulation of soil N over winter (2012), followed by an unseasonably cool, wet spring (2013) sent record levels of stream N into the Mississippi River. Our results show extreme variations in nitrate concentrations and flux associated with pronounced wet/dry cycles, and rapid shifts in hydrologic connectivity within the same year. Information connecting storm events, antecedent environmental conditions and nutrient dynamics is critical for improving our predictions of nitrate loading to riverine networks under increased climatic variation. Furthermore, our findings clearly demonstrate that understanding and

  2. Highly lead-loaded red plastic scintillators as an X-ray imaging system for the Laser Mega Joule

    SciTech Connect

    Hamel, M.; Normand, S.; Turk, G.; Darbon, S.

    2011-07-01

    The scope of this project intends to record spatially resolved images of core shape and size of a DT micro-balloon during Inertial Confinement Fusion (ICF) experiments at Laser Mega Joule facility (LMJ). We need to develop an X-ray imaging system which can operate in the radiative background generated by an ignition shot of ICF. The scintillator is a part of the imaging system and has to gather a compromise of scintillating properties (scintillating efficiency, decay time, emission wavelength) so as to both operate in the hard radiative environment and to allow the acquisition of spatially resolved images. Inorganic scintillators cannot be used because no compromise can be found regarding the expected scintillating properties, most of them are not fast enough and emit blue light. Organic scintillators are generally fast, but present low X-ray absorption in the 10 to 40 keV range, that does not permit the acquisition of spatially resolved images. To this aim, we have developed highly lead-loaded and red-fluorescent fast plastic scintillators. Such a combination is not currently available via scintillator suppliers, since they propose only blue-fluorescent plastic scintillators doped with up to 12%w Pb. Thus, incorporation ratio up to 27%w Pb has been reached in our laboratory, which can afford a plastic scintillator with an outstanding Z{sub eff} close to 50. X-rays in the 10 to 40 keV range can thus be detected with a higher probability of photoelectric effect than for classic organic scintillators, such as NE102. The strong orange-red fluorescence can be filtered, so that we can eliminate residual Cerenkov light, generated by {gamma}-ray absorption in glass parts of the imaging system. Decay times of our scintillators evaluated under UV excitation were estimated to be in the range 10 to 13 ns. (authors)

  3. Operational experience and performance characteristics of a valve-regulated lead-acid battery energy-storage system for providing the customer with critical load protection and energy-management benefits at a lead-recycling plant

    NASA Astrophysics Data System (ADS)

    Hunt, G. W.

    The Power Control Division of GNB Technologies, commissioned on May 13, 1996 a new facility which houses a 5-MW battery energy-storage system (BESS) at GNB's Lead Recycling Centre in Vernon, CA. When the plant loses utility power (which typically happens two or three times a year), the BESS will provide up to 5 MW of power at 4160 VAC in support of all the plant loads. Since the critical loads are not isolated, it is necessary to carry the entire plant load (maximum of 5 MVA) for a short period immediately following an incident until non-critical loads have been automatically shed. Plant loading typically peaks at 3.5 MVA with critical loads of about 2.1 MVA. The BESS also provides the manufacturing plant with customer-side-of-the-meter energy management options to reduce its energy demand during peak periods of the day. The BESS has provided a reduction in monthly electric bills through daily peak-shaving. By design, the battery can provide up to 2.5 MWh of energy and still retain 2.5 MWh of capacity in reserve to handle the possibility of a power outage in protecting the critical loads for up to 1 h. By storing energy from the utility during off-peak hours of the night in the batteries when the cost is low (US4.5¢ per kWh), GNB can then discharge this energy during high demand periods of the day (US14.50 per kW). For example, by reducing its peak demand by 300 kW, the lead-recycling centre can save over US4000 per month in its electric bills. The BESS at Vernon represents a first large-scale use of valve-regulated lead-acid batteries in such a demanding application. This paper presents a summary of the operational experience and performance characteristics of the BESS over the past 2 years.

  4. Dust Detector

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.

    2001-01-01

    We discuss a recent sounding rocket experiment which found charged dust in the Earth's tropical mesosphere. The dust detector was designed to measure small (5000 - 10000 amu.) charged dust particles, most likely of meteoric origin. A 5 km thick layer of positively charged dust was found at an altitude of 90 km, in the vicinity of an observed sporadic sodium layer and sporadic E layer. The observed dust was positively charged in the bulk of the dust layer, but was negatively charged near the bottom.

  5. Cosmic dust

    NASA Technical Reports Server (NTRS)

    Brownlee, Donald E.; Sandford, Scott A.

    1992-01-01

    Dust is a ubiquitous component of our galaxy and the solar system. The collection and analysis of extraterrestrial dust particles is important to exobiology because it provides information about the sources of biogenically significant elements and compounds that accumulated in distant regions of the solar nebula and that were later accreted on the planets. The topics discussed include the following: general properties of interplanetary dust; the carbonaceous component of interplanetary dust particles; and the presence of an interstellar component.

  6. Sahara Dust

    Atmospheric Science Data Center

    2013-04-15

    article title:  Casting Light and Shadows on a Saharan Dust Storm     ... (nadir) camera. High-altitude cirrus clouds cast shadows on the underlying ocean and dust layer, which are visible in shades of ... was unable to retrieve elevation data. However, the edges of shadows cast by the cirrus clouds onto the dust (indicated by blue and cyan ...

  7. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title:  Massive Dust Storm over Australia     View ... at JPL September 22, 2009 - Massive dust storm over Australia. project:  MISR category:  ... Sep 22, 2009 Images:  Dust Storm location:  Australia and New Zealand ...

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

    NASA Technical Reports Server (NTRS)

    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

  9. Microscale failure mechanisms leading to internal short circuit in Li-ion batteries under complex loading scenarios

    NASA Astrophysics Data System (ADS)

    Sahraei, Elham; Bosco, Emanuela; Dixon, Brandy; Lai, Benjamin

    2016-07-01

    One of the least understood mechanisms of Li-ion batteries is the development of internal short circuits under mechanical loads. In this study, a micro mechanical model is developed and subjected to various loading scenarios to understand the sequence of failure in the multi-layer, multi-material structure of a Li-ion battery jellyroll. The constitutive response of each component of the electrode stack is obtained by comprehensive experimental tests using uniaxial and biaxial tensile and compressive loads. The homogenized response of the model is recovered through the computational homogenization theory. The model is validated by comparing the results of a macroscale simulation against experimental data. The study focuses next on the development of a failure criterion for the electrode stack based on the microstructural observations. Results show distinct failure mechanisms when the loading is predominantly tensile versus when it is compressive or combined tensile/compressive. A failure locus is plotted from the results of the simulations as a criterion to detect the onset of short circuit under complex multi-axial loading scenarios.

  10. Circumstellar dust

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    1986-01-01

    The presence of dust in the general interstellar medium is inferred from the extinction, polarization, and scattering of starlight; the presence of dark nebulae; interstellar depletions; the observed infrared emission around certain stars and various types of interstellar clouds. Interstellar grains are subject to various destruction mechanisms that reduce their size or even completely destroy them. A continuous source of newly formed dust must therefore be present for dust to exist in the various phases of the interstellar medium (ISM). The working group has the following goals: (1) review the evidences for the formation of dust in the various sources; (2) examine the clues to the nature and composition of the dust; (3) review the status of grain formation theories; (4) examine any evidence for the processing of the dust prior to its injection into the interstellar medium; and (5) estimate the relative contribution of the various sources to the interstellar dust population.

  11. Microgravity combustion of dust clouds: Quenching distance measurements

    NASA Technical Reports Server (NTRS)

    Goroshin, S.; Kleine, H.; Lee, J. H. S.; Frost, D.

    1995-01-01

    The current level of physical understanding of dust combustion phenomena is still in a rudimentary state compared with the understanding of gas combustion processes. The reason for such a lack of fundamental understanding is partially based on the complexity of multiphase combustion and the enormous diversity of chemical-physical properties of heterogeneous combustible mixtures but is largely due to difficulties in the experimental investigation of dust combustion. The influence of gravity on a dust suspension is the main reason. First of all, when particulates (either solid particles or liquid droplets) with a characteristic size of the order of tens of microns are suspended, they rapidly settle in the gravitational field. To maintain a particulate suspension for a time duration adequate to carry out combustion experiments invariably requires continuous convection of particulates at or in excess of the gravitational settling velocity. Of necessity, this makes the experiments turbulent in character and makes it impossible to study laminar dust flames. For particle sizes of the order of microns a stable laminar dust flow can be maintained only for relatively small dust concentrations (e.g., for low fuel equivalence ratios) at normal gravity conditions. High dust loading leads to gravitational instability of the dust cloud and to the formation of recirculation cells in a dust suspension in a confined volume, or to the rapid sedimentation of the dense dust cloud as a whole in an unconfined volume. In addition, many important solid fuels such as low volatile coal, carbon, and boron have low laminar flame speeds (of the order of several centimeters per second). Gravitational convection that occurs in combustion products due to the buoyancy forces disrupts low speed dust flames and, therefore, makes observation of such flames at normal gravity impossible. The only way to carry out 'clean' fundamental experiments in dust combustion over a wide range of dust cloud

  12. Lunar Dust Mitigation Screens

    NASA Astrophysics Data System (ADS)

    Knutson, Shawn; Holloway, Nancy

    With plans for the United States to return to the moon, and establish a sustainable human presence on the lunar surface many issues must be successfully overcome. Lunar dust is one of a number of issues with the potential to create a myriad of problems if not adequately addressed. Samples of dust brought back from Apollo missions show it to be soft, yet sharp and abrasive. The dust consists of a variety of morphologies including spherical, angular blocks, shards, and a number of irregular shapes. One of the main issues with lunar dust is its attraction to stick to anything it comes in contact with (i.e. astronauts, equipment, habitats, etc.). Ionized radiation from the sun strikes the moon's surface and creates an electrostatic charge on the dust. Further, the dust harbors van der Waals forces making it especially difficult to separate once it sticks to a surface. During the Apollo missions, it was discovered that trying to brush the lunar dust from spacesuits was not effective, and rubbing it caused degradation of the suit material. Further, when entering the lunar module after moonwalks, the astronauts noted that the dust was so prolific inside the cabin that they inhaled and ingested it, causing at least one of them, Harrison "Jack" Schmidt, to report irritation of the throat and lungs. It is speculated that the dust could also harm an astronaut's nervous and cardiovascular systems, especially during an extended stay. In addition to health issues, the dust can also cause problems by scouring reflective coatings off of thermal blankets, and roughening surfaces of windows and optics. Further, panels on solar cells and photovoltaics can also be compromised due to dust sticking on the surfaces. Lunar dust has the capacity to penetrate seals, interfere with connectors, as well as mechanisms on digging machines, all of which can lead to problems and failure. To address lunar dust issues, development of electrostatic screens to mitigate dust on sur-faces is currently

  13. Concentrations and loads of cadmium, zinc, and lead in the main stem Coeur d'Alene River, Idaho—March, June, September, and October 1999

    USGS Publications Warehouse

    Woods, P.F.

    2001-01-01

    of the effects of different river discharges and lake levels of Coeur d'Alene Lake on the transport of cadmium, zinc, and lead within the main stem Coeur d'Alene River. In particular, water-quality data and loads during a broad range of hydrologic conditions were examined to determine if the river channel, flood plain, and associated ground water along the main stem Coeur d'Alene River acted as sources or sinks of trace elements. Water-quality samples were collected at six riverine stations and one lake station along a 35-mile reach during March, June, September, and October of 1999. Samples were analyzed for whole-water recoverable, filtered (0.45 micrometer), and dissolved (0.01 micrometer) concentrations of cadmium, zinc, and lead. Concentrations and loads of cadmium and zinc measured during the four sampling trips were predominately in the filtered and dissolved fraction ,rather than particulate. The smallest concentrations were measured during the June sampling trip when flows were high and snowmelt runoff diluted riverine concentrations. Conversely, the largest concentrations were measured during the latter two sampling trips when flows were low because a larger proportion of the river's discharge was contributed by ground-water inflow. During each sampling trip, cadmium and zinc concentrations generally decreased in a downstream directioeven as discharge increased in a downstream direction. Spatial and temporal trends exhibited by lead concentrations and loads during the four sampling trips were different from those of cadmium and zinc because of the propensity for lead to adsorb to sediment particles. Whole-water recoverable lead concentrations and loads during the four sampling trips were predominantly in the particulate fraction, with filtered and dissolved concentrations and loads composing a much smaller proportion of the recoverable fraction compared to cadmium and zinc. Filtered lead concentrations generally increased at a faster rate in the

  14. Comments on Dust Reverberation

    NASA Astrophysics Data System (ADS)

    Peterson, B.

    2015-09-01

    Dust reverberation is an important technique for studying the inner structure of AGNs and probing the properties of astrophysical dust, and even has some potential as a cosmological probe. We will discuss two recent results that pose a serious limitation to understanding dust reverberation at the present time. First, recent high-cadence monitoring of the UV and optical continuum in two AGNs, NGC 2617 and NGC 5548, have yielded unambiguous lags between variations of the UV continuum and corresponding variations of the continuum at longer wavelengths. In the absence of UV data, this leads to a systematic underestimate of the innermost radius where dust is found. This similarly leads to an underestimate of the size of the broad emission-line region, although it does not affect the AGN black hole mass scale, which calibrates out this effect. Second, broad-band monitoring of continuum variations in the optical through near-IR show that the innermost dust is not necessarily at the 'instantaneous sublimation radius.' The innermost dust can be considerably cooler than expected at the sublimation radius and thus can heat up without sublimating when the central continuum source becomes more luminous (see the poster by Pott).

  15. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, Dániel; Lauretta, Dante S.

    2010-01-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  16. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, D.´niel; Lauretta, Dante S.

    2014-02-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  17. Alteration of the diffusional barrier property of the nail leads to greater terbinafine drug loading and permeation.

    PubMed

    Nair, Anroop B; Sammeta, Srinivasa M; Kim, Hyun D; Chakraborty, Bireswar; Friden, Phillip M; Murthy, S Narasimha

    2009-06-22

    The diffusional barrier property of biological systems varies with ultrastructural organization of the tissues and/or cells, and often plays an important role in drug delivery. The nail plate is a thick, hard and impermeable membrane which makes topical nail drug delivery challenging. The current study investigated the effect of physical and chemical alteration of the nail on the trans-ungual drug delivery of terbinafine hydrochloride (TH) under both passive and iontophoretic conditions. Physical alterations were carried out by dorsal or ventral nail layer abrasion, while chemical alterations were performed by defatting or keratolysis or ionto-keratolysis of the nails. Terbinafine permeation into and across the nail plate following various nail treatments showed similar trends in both passive and iontophoretic delivery, although the extent of drug delivery varied with treatment. Application of iontophoresis to the abraded nails significantly improved (P<0.05) TH permeation and loading compared to abraded nails without iontophoresis or normal nails with iontophoresis. Drug permeation was not enhanced when the nail plate was defatted. Keratolysis moderately enhanced the permeation but not the drug load. Ionto-keratolysis enhanced TH permeation and drug load significantly (P<0.05) during passive and iontophoretic delivery as compared to untreated nails. Ionto-keratolysis may be more efficient in permeabilization of nail plates than long term exposure to keratolysing agents. PMID:19481686

  18. Window replacement and residential lead paint hazard control 12 years later.

    PubMed

    Dixon, Sherry L; Jacobs, David E; Wilson, Jonathan W; Akoto, Judith Y; Nevin, Rick; Scott Clark, C

    2012-02-01

    Window replacement is a key method of reducing childhood lead exposure, but the long-term effectiveness has not been previously evaluated. Windows have the highest levels of interior lead paint and dust compared to other building components. Our objective was to conduct a follow-up study of residential window replacement and lead hazard control 12 years after homes were enrolled in an evaluation of the HUD Lead Hazard Control Grant Program, sampling settled lead dust in housing in four cities (n=189 homes). Previous work evaluated lead hazard controls up to 6 years after intervention using dust lead measurements and two years after intervention using both dust and blood lead data. But the earlier work could not examine the effect of window replacement over the longer time period examined here: 12 years. The individual homes were assigned to one of three categories, based on how many windows had been replaced: all replacement, some replacement, or non-replacement. Windows that were not replaced were repaired. We controlled for covariates such as site, housing condition, presence of lead paint, and season using longitudinal regression modeling. Adjusted floor and sill dust lead geometric mean dust lead loadings declined at least 85% from pre-intervention to 12 years after the intervention for homes with all replacement windows, some windows replaced and no windows replaced. Twelve years after intervention, homes with all replacement windows had 41% lower interior floor dust lead, compared to non-replacement homes (1.4 versus 2.4 μg/ft2, p<0.001), and window sill dust lead was 51% lower (25 versus 52 μg/ft2, p=0.006) while controlling for covariates. Homes with some windows replaced had interior floor and window sill dust lead loadings that were 28% (1.7 versus 2.4 μg/ft2, p=0.19) and 37% (33 versus 52 μg/ft2, p=0.07) lower, respectively, compared to non-replacement homes. The net economic benefit of window replacement compared to window repair (non

  19. Saharan dust aerosol over the central Mediterranean Sea: optical columnar measurements vs. aerosol load, chemical composition and marker solubility at ground level

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Sferlazzo, D. M.; Becagli, S.; Bommarito, C.; Calzolai, G.; Chiari, M.; di Sarra, A.; Ghedini, C.; Gómez-Amo, J. L.; Lucarelli, F.; Meloni, D.; Monteleone, F.; Nava, S.; Pace, G.; Piacentino, S.; Rugi, F.; Severi, M.; Traversi, R.; Udisti, R.

    2013-08-01

    This study aims at the determination of the mineral contribution to PM10 in the central Mediterranean Sea on the basis of 7 yr of PM10 chemical composition daily measurements made on the island of Lampedusa (35.5° N, 12.6° E). Aerosol optical depth measurements are carried out in parallel while sampling with a multi-stage impactor, and observations with an optical particle counter were performed in selected periods. Based on daily samples, the total content and soluble fraction of selected metals are used to identify and characterize the dust events. The total contribution is determined by PIXE (particle-induced X-ray emission) while the composition of the soluble fraction by ICP-AES (inductively coupled plasma atomic emission spectroscopy) after extraction with HNO3 at pH 1.5. The average PM10 concentration at Lampedusa calculated over the period June 2004-December 2010 is 31.5 μg m-3, with low interannual variability. The annual means are below the EU annual standard for PM10, but 9.9% of the total number of daily data exceed the daily threshold value established by the European Commission for PM (50 μg m-3, European Community, EC/30/1999). The Saharan dust contribution to PM10 was derived by calculating the contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides in samples in which PIXE data were available. Cases with crustal content exceeding the 75th percentile of the crustal oxide content distribution were identified as dust events. Using this threshold we identify 175 events; 31.6% of them (55 events) present PM10 higher than 50 μg m-3, with dust contributing by 33% on average. The annual average crustal contribution to PM10 is 5.42 μg m-3, reaching a value as high as 67.9 μg m-3, 49% of PM10, during an intense Saharan dust event. The crustal aerosol amount and contribution to PM10 shows a very small seasonal dependence; conversely, the dust columnar burden displays an evident annual cycle, with a strong summer maximum (monthly

  20. An evaluation of the effectiveness of lead paint hazard reduction when conducted by homeowners and landlords

    SciTech Connect

    Etre, L.A.; Reynolds, S.J.; Burmeister, L.F.; Whitten, P.S.; Gergely, R.

    1999-08-01

    This research project was conducted in collaboration with the Iowa Department of Public Health to evaluate whether property owners who follow recommended procedures for lead-based paint removal/repair can do the work safely and effectively. This study included 29 homes where a lead-based paint hazard had been identified and lead-based paint was removed or repaired (hazard reduction). Exposure evaluation included pre-project surface dust wipe sampling, air monitoring during lead-based paint removal, post-project surface dust wipe sampling, and pre- and post-project blood samples from adult study participants. The comparison of surface dust wipe samples taken before and after lead paint hazard reduction was used to evaluate the effectiveness of lead paint hazard reduction. The lead loadings on window sill surfaces in the work area were significantly lower after completion of the project, and the lead-based paint removal did not contaminate the adjoining living area. The proportion of homes with surface dust lead loading exceeding Department of Housing and Urban Development (HUD) clearance standard was 73% pre-project and 38% post-project. Personal airborne exposures during lead removal activities reinforce the need to respiratory protection and good hygiene. There was no difference in adult pre-/post-blood levels, indicating that participants die remove lead in a safe manner with respect to their own exposures. The results indicate that hazard reduction can be done effectively when recommended procedures for the removal of lead-based paint are followed.

  1. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    ... contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom panels). These data products from ... as yellowish ripples that obscure a large part of southern Iraq. The dust is easy to discern over the dark waters of the teardrop-shaped ...

  2. Andromeda's dust

    SciTech Connect

    Draine, B. T.; Aniano, G.; Krause, Oliver; Groves, Brent; Sandstrom, Karin; Klaas, Ulrich; Linz, Hendrik; Rix, Hans-Walter; Schinnerer, Eva; Schmiedeke, Anika; Walter, Fabian; Braun, Robert; Leroy, Adam E-mail: ganiano@ias.u-psud.fr

    2014-01-10

    Spitzer Space Telescope and Herschel Space Observatory imaging of M31 is used, with a physical dust model, to construct maps of dust surface density, dust-to-gas ratio, starlight heating intensity, and polycyclic aromatic hydrocarbon (PAH) abundance, out to R ≈ 25 kpc. The global dust mass is M {sub d} = 5.4 × 10{sup 7} M {sub ☉}, the global dust/H mass ratio is M {sub d}/M {sub H} = 0.0081, and the global PAH abundance is (q {sub PAH}) = 0.039. The dust surface density has an inner ring at R = 5.6 kpc, a maximum at R = 11.2 kpc, and an outer ring at R ≈ 15.1 kpc. The dust/gas ratio varies from M {sub d}/M {sub H} ≈ 0.026 at the center to ∼0.0027 at R ≈ 25 kpc. From the dust/gas ratio, we estimate the interstellar medium metallicity to vary by a factor ∼10, from Z/Z {sub ☉} ≈ 3 at R = 0 to ∼0.3 at R = 25 kpc. The dust heating rate parameter (U) peaks at the center, with (U) ≈ 35, declining to (U) ≈ 0.25 at R = 20 kpc. Within the central kiloparsec, the starlight heating intensity inferred from the dust modeling is close to what is estimated from the stars in the bulge. The PAH abundance reaches a peak q {sub PAH} ≈ 0.045 at R ≈ 11.2 kpc. When allowance is made for the different spectrum of the bulge stars, q {sub PAH} for the dust in the central kiloparsec is similar to the overall value of q {sub PAH} in the disk. The silicate-graphite-PAH dust model used here is generally able to reproduce the observed dust spectral energy distribution across M31, but overpredicts 500 μm emission at R ≈ 2-6 kpc, suggesting that at R = 2-6 kpc, the dust opacity varies more steeply with frequency (with β ≈ 2.3 between 200 and 600 μm) than in the model.

  3. Dust transport into Martian polar latitudes

    NASA Technical Reports Server (NTRS)

    Murphy, J. R.; Pollack, J. B.

    1992-01-01

    The presence of suspended dust in the Martian atmosphere, and its return to the planet's surface, is implicated in the formation of the polar layered terrain and the dichotomy in perennial CO2 polar cap retention in the two hemispheres. A three dimensional model was used to study Martian global dust storms. The model accounts for the interactive feedbacks between the atmospheric thermal and dynamical states and an evolving radiatively active suspended dust load. Results from dust storm experiments, as well as from simulations in which there is interest in identifying the conditions under which surface dust lifting occurs at various locations and times, indicate that dust transport due to atmospheric eddy motions is likely to be important in the arrival of suspended dust at polar latitudes. The layered terrain in both polar regions of Mars is interpreted as the reality of cyclical episodes of volatile (CO2, H2O) and dust deposition.

  4. Conveyor dust control

    SciTech Connect

    Goldbeck, L.

    1999-11-01

    In the past, three different approaches have been used to control dust arising at conveyor load zones. They are: Dust Containment consists of those mechanical systems employed to keep material inside the transfer point with the main material body. Dust Suppression systems increase the mass of suspended dust particles, allowing them to fall from the air stream. Dust Collection is the mechanical capture and return of airborne material after it becomes airborne from the main material body. Previously, these three approaches have always been seen as separate entities. They were offered by separate organizations competing in the marketplace. The three technologies vied for their individual piece of the rock, at the expense of the other technologies (and often at the expense of overall success). There have been considerable amounts of I`m better selling, as well as finger pointing at the other systems when problems arose. Each system claimed its own technology was the best, providing the most effective, most cost-efficient, most maintenance-free solution to fugitive material.

  5. Replacement of lead-loaded glovebox glove with attenuation medium that are not RCRA-hazardous metals

    SciTech Connect

    Cournoyer, Michael E; George, Gerald L; Dodge, Robert L; Chunglo, Steve

    2010-01-01

    Programmatic operations at the Los Alamos National Laboratory Plutonium Facility (TA-55) involve working with various amounts of plutonium and other highly toxic, alpha-emitting materials. The spread of radiological contamination on surfaces, airborne contamination, and excursions of contaminants into the operator's breathing zone are prevented through the use of a variety of gloveboxes (the glovebox, coupled with an adequate negative pressure gradient, provides primary confinement). Radiation shielding is commonly used to protect the glovebox worker from unintentional direct and secondary radiation exposure, while working with plutonium-238 and plutonium-239. In these environments, low-energy photons, i.e., those less than 250 keY, are encountered. Shielding glove box gloves are traditionally composed of lead-based materials, but these are now considered hazardous waste. This has prompted the development of new, nonhazardous- shielding gJovebox gloves. No studies, however, have investigated the effectiveness of these new glovebox gloves. We examined both leaded and nonhazardous- shielding glovebox gloves and compared their attenuation effectiveness over the energy range of interest at TA-55. All measurements are referenced to lead sheets, allowing direct comparisons to the common industry standard of 0.1 mm lead equivalent material. The attenuation properties of both types of glovebox gloves vary with energy, making it difficult for manufacturers to claim lead equivalency across the entire energy range used at TA-55. The positions of materials' photon energy absorption edges, which are particularly important to improved attenuation performance, depending upon the choice of radiation energy range, are discussed. This effort contributes to the Los Alamos National Laboratory Continuous Improvement Program by improving the efficiency, cost effectiveness, and formality of glovebox operations.

  6. Differential dust attenuation in CALIFA galaxies

    NASA Astrophysics Data System (ADS)

    Vale Asari, N.; Cid Fernandes, R.; Amorim, A. L.; Lacerda, E. A. D.; Schlickmann, M.; Wild, V.; Kennicutt, R. C.

    2016-06-01

    Dust attenuation has long been treated as a simple parameter in SED fitting. Real galaxies are, however, much more complicated: The measured dust attenuation is not a simple function of the dust optical depth, but depends strongly on galaxy inclination and the relative distribution of stars and dust. We study the nebular and stellar dust attenuation in CALIFA galaxies, and propose some empirical recipes to make the dust treatment more realistic in spectral synthesis codes. By adding optical recombination emission lines, we find better constraints for differential attenuation. Those recipes can be applied to unresolved galaxy spectra, and lead to better recovered star formation rates.

  7. Catalyst-dependent drug loading of LDI-glycerol polyurethane foams leads to differing controlled release profiles.

    PubMed

    Sivak, Wesley N; Pollack, Ian F; Petoud, Stéphane; Zamboni, William C; Zhang, Jianying; Beckman, Eric J

    2008-09-01

    The purpose of the present study was to develop biodegradable and biocompatible polyurethane foams based on lysine diisocyanate (LDI) and glycerol to be used as drug-delivery systems for the controlled release of 7-tert-butyldimethylsilyl-10-hydroxy-camptothecin (DB-67). The impact of urethane catalysts on cellular proliferation was assessed in an attempt to enhance the biocompatibility of our polyurethane materials. DB-67, a potent camptothecin analog, was then incorporated into LDI-glycerol polyurethane foams with two different amine urethane catalysts: 1,4-diazobicyclo[2.2.2]-octane (DABCO) and 4,4'-(oxydi-2,1-ethane-diyl)bismorpholine (DMDEE). The material morphologies of the polyurethane foams were analyzed via scanning electron microscopy, and DB-67 distribution was assessed by way of fluorescence microscopy. Both foam morphology and drug distribution were found to correlate to the amine catalyst used. Hydrolytic release rates of DB-67 from the polyurethane foams were catalyst dependent and also demonstrated greater drug loads being released at higher temperatures. The foams were capable of delivering therapeutic concentrations of DB-67 in vitro over an 11week test period. Cellular proliferation assays demonstrate that empty LDI-glycerol foams did not significantly alter the growth of malignant human glioma cell lines (P<0.05). DB-67 loaded LDI-glycerol polyurethane foams were found to inhibit cellular proliferation by at least 75% in all the malignant glioma cell lines tested (P<1.0x10(-8)). These results clearly demonstrate the long-term, catalyst-dependent release of DB-67 from LDI-glycerol polyurethane foams, indicating their potential for use in implantable drug-delivery devices. PMID:18440884

  8. Lunar Dust Characterization for Exploration Life Support Systems

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.

    2007-01-01

    Lunar dust effects can have a significant impact on the performance and maintenance of future exploration life support systems. Filtration systems will be challenged by the additional loading from lunar dust, and mitigation technology and strategies have to be adapted to protect sensitive equipment. An initial characterization of lunar dust and simulants was undertaken. The data emphasize the irregular morphology of the dust particles and the frequency dependence of lunar dust layer detachment from shaken surfaces.

  9. Prediction of unsteady aerodynamic loadings caused by leading edge and trailing edge control surface motions in subsonic compressible flow: Computer program description

    NASA Technical Reports Server (NTRS)

    Redman, M. C.; Rowe, W. S.

    1975-01-01

    A digital computer program has been developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge or trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges have been extracted analytically as a preliminary step to solving the integral equation by collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accommodated.

  10. Planetary Magnetosphere Probed by Charged Dust Particles

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  11. The physics of wind-blown sand and dust.

    PubMed

    Kok, Jasper F; Parteli, Eric J R; Michaels, Timothy I; Karam, Diana Bou

    2012-10-01

    The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan. PMID:22982806

  12. Exozodiacal dust

    NASA Astrophysics Data System (ADS)

    Kuchner, Marc Jason

    Besides the sun, the most luminous feature of the solar system is a cloud of "zodiacal" dust released by asteroids and comets that pervades the region interior to the asteroid belt. Similar clouds of dust around other stars---exozodiacal clouds---may be the best tracers of the habitable zones of extra-solar planetary systems. This thesis discusses three searches for exozodiacal dust: (1) We observed six nearby main-sequence stars with the Keck telescope at 11.6 microns, correcting for atmosphere-induced wavefront aberrations and deconvolving the point spread function via classical speckle analysis. We compare our data to a simple model of the zodiacal dust in our own system based on COBE DIRBE observations and place upper limits on the density of exozodiacal dust in these systems. (2) We observed Sirius, Altair, and Procyon with the NICMOS Coronagraph on the Hubble Space Telescope to look for scattered light from exozodiacal dust and faint companions within 10 AU from these stars. (3) The planned nulling capability of the Keck Interferometer should allow it to probe the region <200 milliarcsecond from a bright star and to suppress on-axis starlight by factors of 10 -3 to reveal faint circumstellar material. We model the response of the Keck Interferometer to hypothetical exozodiacal clouds to derive detection limits that account for the effects of stellar leakage, photon noise, noise from null depth fluctuations, and the fact that the cloud's shape is not known a priori. We also discuss the interaction of dust with planets. We used the COBE DIRBE Sky and Zodi Atlas and the IRAS Sky Survey Atlas to search for dynamical signatures of three different planets in the solar system dust complex: (1) We searched the COBE DIRBE Sky and Zodi Atlas for a wake of dust trailing Mars. We compare the DIRBE images to a model Mars wake based on the empirical model of the Earth's wake as seen by the DIRBE. (2) We searched the COBE DIRRE Sky and Zodi Atlas for Tiojan dust near

  13. Substantial dust loss of bioavailable phosphorus from agricultural soils.

    PubMed

    Katra, Itzhak; Gross, Avner; Swet, Nitzan; Tanner, Smadar; Krasnov, Helena; Angert, Alon

    2016-01-01

    Phosphorus (P) is an essential element in terrestrial ecosystems. Knowledge on the role of dust in the biogeochemical cycling of phosphorus is very limited with no quantitative information on aeolian (by wind) P fluxes from soils. The aim of this study is to focus on P cycling via dust emissions under common land-use practices in an arid environment by integration of sample analyses and aeolian experiments. The experiments indicate significant P fluxes by PM10 dust due to agricultural land use. Even in a single wind-dust event at moderate velocity (7.0 m s(-1)), P flux in conventional agricultural fields can reach 1.83 kg km(-2), that accumulates to a considerable amount per year at a regional scale. The results highlight a negative yearly balance in P content (up to hundreds kg km(-2)) in all agricultural soils, and thus more P nutrition is required to maintain efficient yield production. In grazing areas where no P nutrition is applied, the soil degradation process can lead to desertification. Emission of P from soil dust sources has significant implications for soil nutrient resources and management strategies in agricultural regions as well as for loading to the atmosphere and global biogeochemical cycles. PMID:27095629

  14. Substantial dust loss of bioavailable phosphorus from agricultural soils

    PubMed Central

    Katra, Itzhak; Gross, Avner; Swet, Nitzan; Tanner, Smadar; Krasnov, Helena; Angert, Alon

    2016-01-01

    Phosphorus (P) is an essential element in terrestrial ecosystems. Knowledge on the role of dust in the biogeochemical cycling of phosphorus is very limited with no quantitative information on aeolian (by wind) P fluxes from soils. The aim of this study is to focus on P cycling via dust emissions under common land-use practices in an arid environment by integration of sample analyses and aeolian experiments. The experiments indicate significant P fluxes by PM10 dust due to agricultural land use. Even in a single wind-dust event at moderate velocity (7.0 m s−1), P flux in conventional agricultural fields can reach 1.83 kg km−2, that accumulates to a considerable amount per year at a regional scale. The results highlight a negative yearly balance in P content (up to hundreds kg km−2) in all agricultural soils, and thus more P nutrition is required to maintain efficient yield production. In grazing areas where no P nutrition is applied, the soil degradation process can lead to desertification. Emission of P from soil dust sources has significant implications for soil nutrient resources and management strategies in agricultural regions as well as for loading to the atmosphere and global biogeochemical cycles. PMID:27095629

  15. Substantial dust loss of bioavailable phosphorus from agricultural soils

    NASA Astrophysics Data System (ADS)

    Katra, Itzhak; Gross, Avner; Swet, Nitzan; Tanner, Smadar; Krasnov, Helena; Angert, Alon

    2016-04-01

    Phosphorus (P) is an essential element in terrestrial ecosystems. Knowledge on the role of dust in the biogeochemical cycling of phosphorus is very limited with no quantitative information on aeolian (by wind) P fluxes from soils. The aim of this study is to focus on P cycling via dust emissions under common land-use practices in an arid environment by integration of sample analyses and aeolian experiments. The experiments indicate significant P fluxes by PM10 dust due to agricultural land use. Even in a single wind-dust event at moderate velocity (7.0 m s‑1), P flux in conventional agricultural fields can reach 1.83 kg km‑2, that accumulates to a considerable amount per year at a regional scale. The results highlight a negative yearly balance in P content (up to hundreds kg km‑2) in all agricultural soils, and thus more P nutrition is required to maintain efficient yield production. In grazing areas where no P nutrition is applied, the soil degradation process can lead to desertification. Emission of P from soil dust sources has significant implications for soil nutrient resources and management strategies in agricultural regions as well as for loading to the atmosphere and global biogeochemical cycles.

  16. Design and commissioning of a valve-regulated lead/acid battery energy-storage system for backing up critical environmental loads

    NASA Astrophysics Data System (ADS)

    Hunt, G. W.

    Momentary and sustained electrical power interruptions and voltage depressions represent two of the most difficult and important power quality and delivery problems that face many industrial and commercial users. There is a definite need at many industrial processing plants and commercial users of electrical power to have a dependable, efficient and controllable source of real and reactive power that is available instantly to support large electrical loads (greater than 5 MVA), even if the incoming utility a.c. connection is lost. When power is interrupted or lost, the results can be extremely disruptive for critical processes and cause lost production, costly downtime and loss of customer good will, and in certain industries, can lead to environmental damage through the release of toxic emissions into the air. Recently, this challenge was faced by GNB Technologies at its lead reclaiming and smelting facility in Vernon, CA, USA. This study describes a versatile, cost-effective, workable solution to the problem that has resulted in the design and installation of a 5 MVA, 3.5 MWh battery energy storage system (BESS) which provides uninterruptible power to the critical environmental control equipment throughout the plant. The BESS at Vernon provides the required power, combined with both voltage and frequency control, to allow the plant to tolerate disconnection from the utility grid without suffering unacceptable impacts on critical loads. The system also provides the company with a demand-side energy management system for conducting daily peak shaving of energy demand and, thereby, reduces its electrical bills.

  17. Size-Resolved Dust and Aerosol Contaminants Associated with Copper and Lead Smelting Emissions: Implications for Emissions Management and Human Health

    PubMed Central

    Csavina, Janae; Taylor, Mark P.; Félix, Omar; Rine, Kyle P.; Sáez, A. Eduardo; Betterton, Eric A.

    2014-01-01

    Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (< 1 μm) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (< 1 μm) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emissions management and practices that minimize health risks associated with metal extraction and processing can be developed. PMID:24995641

  18. Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: implications for emission management and human health.

    PubMed

    Csavina, Janae; Taylor, Mark P; Félix, Omar; Rine, Kyle P; Eduardo Sáez, A; Betterton, Eric A

    2014-09-15

    Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (<1 μm) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (<1 μm) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emission management and practices that minimize health risks associated with metal extraction and processing can be developed. PMID:24995641

  19. Evaluation of HEPA vacuum cleaning and dry steam cleaning in reducing levels of polycyclic aromatic hydrocarbons and house dust mite allergens in carpets

    PubMed Central

    Yu, Chang Ho; Yiin, Lih-Ming; Fan, Zhi-Hua (Tina); Rhoads, George G.

    2014-01-01

    Dry steam cleaning, which has gained recent attention as an effective method to reduce house dust mite (HDM) allergen concentration and loading in carpets, was evaluated in this study for its efficacy in lowering levels of polycyclic aromatic hydrocarbons (PAHs) as well as HDM allergens. Fifty urban homes with wail-to-wall carpets, mostly low-income and with known lead contamination, were studied in 2003 and 2004. Two carpet-cleaning interventions were compared: Repeated HEPA (High Efficiency Particulate Air filtered) vacuuming alone and repeated HEPA vacuuming supplemented with dry steam cleaning. Vacuum samples were collected to measure carpet loading of dust and contaminants immediately before and after cleaning. Paired comparisons were conducted to evaluate the effectiveness of the cleaning protocols in reducing the levels of PAHs and HDM allergens in carpets. The results indicated that both cleaning methods substantially reduced the loading of PAHs and HDM allergens as well as dust in carpets (p < 0.0001). The reductions in loading of dust (64.4%), PAHs (69.1%), and HDM allergens (85.5%), by dry steam cleaning plus repetitive HEPA vacuuming were larger than the reductions by regular HEPA vacuuming alone: dust (55.5%), PAHs (58.6%), and HDM allergens (80.8%), although the difference was statistically significant only for dust and PAHs. We conclude that intensive HEPA vacuum cleaning substantially reduced the loading of PAHs and HDM allergens in carpets in these urban homes and that dry steam cleaning added modestly to cleaning effectiveness. PMID:19137159

  20. Evaluation of HEPA vacuum cleaning and dry steam cleaning in reducing levels of polycyclic aromatic hydrocarbons and house dust mite allergens in carpets.

    PubMed

    Yu, Chang Ho; Yiin, Lih-Ming; Tina Fan, Zhi-Hua; Rhoads, George G

    2009-01-01

    Dry steam cleaning, which has gained recent attention as an effective method to reduce house dust mite (HDM) allergen concentration and loading in carpets, was evaluated in this study for its efficacy in lowering levels of polycyclic aromatic hydrocarbons (PAHs) as well as HDM allergens. Fifty urban homes with wall-to-wall carpets, mostly low-income and with known lead contamination, were studied in 2003 and 2004. Two carpet-cleaning interventions were compared: Repeated HEPA (High Efficiency Particulate Air filtered) vacuuming alone and repeated HEPA vacuuming supplemented with dry steam cleaning. Vacuum samples were collected to measure carpet loading of dust and contaminants immediately before and after cleaning. Paired comparisons were conducted to evaluate the effectiveness of the cleaning protocols in reducing the levels of PAHs and HDM allergens in carpets. The results indicated that both cleaning methods substantially reduced the loading of PAHs and HDM allergens as well as dust in carpets (p < 0.0001). The reductions in loading of dust (64.4%), PAHs (69.1%), and HDM allergens (85.5%), by dry steam cleaning plus repetitive HEPA vacuuming were larger than the reductions by regular HEPA vacuuming alone: dust (55.5%), PAHs (58.6%), and HDM allergens (80.8%), although the difference was statistically significant only for dust and PAHs. We conclude that intensive HEPA vacuum cleaning substantially reduced the loading of PAHs and HDM allergens in carpets in these urban homes and that dry steam cleaning added modestly to cleaning effectiveness. PMID:19137159

  1. Hydrological and ecological implications of radiative forcing by dust in snow

    NASA Astrophysics Data System (ADS)

    Painter, T.; Bryant, A. C.; Deems, J. S.; Skiles, M.

    2012-12-01

    The runoff from the Colorado River supplies water to over 30 million people in seven US states and Mexico. Climate change projections suggest that this runoff will decrease in the next 50 years by 7-20% due to increases in evapotranspiration and decreases in the ratio of snowfall to rain. Such scenarios challenge the sustainability of the freshwater supply to the southwest US. Recent research however has shown that radiative forcing by dust in snow has been shortening snow cover duration by several weeks due to a 5-7-fold increase in dust loading relative to prior to the European-settlement of the western US in the mid-1800s. In the mountains of the Upper Colorado River, the absolute dust radiative forcing across the period ranges from 30 to 75 W m-2, in turn shortening snow cover duration by 21 to 51 days. Extended to the scale of the Upper Colorado River Basin, this impact has brought peak normalized runoff at Lee's Ferry, AZ (Lake Powell) more than three weeks earlier and reduced the total annual runoff by an average of ~5%. In this region, earlier snowmelt forced by dust radiative forcing impacts alpine vegetation by increasing synchronicity in phenology across the alpine landscape with increasingly earlier snowmelt. Whereas reduced dust load results in topographically-sensitive melt and loss of snow cover, the more spatially-uniform snowmelt from dust radiative forcing leads to synchronized growth and flowering across the landscape. Water managers in the Upper Colorado basin now seek detailed real-time knowledge of dust presence, radiative forcing, and its potential to accelerate snowmelt, as well as understanding its implications for water supply under current conditions and in a changed climate. Likewise, water stakeholder groups, water conservation districts, and state and federal agencies are discussing efforts to restabilize soil surfaces in the dust-emitting regions to mitigate impacts of dust on snowmelt and runoff. However, as these policy

  2. 2-DUST: Dust radiative transfer code

    NASA Astrophysics Data System (ADS)

    Ueta, Toshiya; Meixner, Margaret

    2016-04-01

    2-DUST is a general-purpose dust radiative transfer code for an axisymmetric system that reveals the global energetics of dust grains in the shell and the 2-D projected morphologies of the shell that are strongly dependent on the mixed effects of the axisymmetric dust distribution and inclination angle. It can be used to model a variety of axisymmetric astronomical dust systems.

  3. Circumstellar dust in symbiotic novae

    NASA Astrophysics Data System (ADS)

    Jurkic, Tomislav; Kotnik-Karuza, Dubravka

    2015-08-01

    Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding evolution of symbiotic binaries. We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the long-term near-IR photometry, infrared ISO spectra and mid-IR interferometry. Pulsation properties and long-term variabilities were found from the near-IR light curves. The dust properties were determined using the DUSTY code which solves the radiative transfer. No changes in pulsational parameters were found, but a long-term variations with periods of 20-25 years have been detected which cannot be attributed to orbital motion.Circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel showed the presence of an optically thin CS dust envelope and an optically thick dust region outside the line of sight, which was further supported by the detailed modelling using the 2D LELUYA code. Obscuration events in RR Tel were explained by an increase in optical depth caused by the newly condensed dust leading to the formation of a compact dust shell. HM Sge showed permanent obscuration and a presence of a compact dust shell with a variable optical depth. Scattering of the near-IR colours can be understood by a change in sublimation temperature caused by the Mira variability. Presence of large dust grains (up to 4 µm) suggests an increased grain growth in conditions of increased mass loss. The mass loss rates of up to 17·10-6 MSun/yr were significantly higher than in intermediate-period single Miras and in agreement with longer-period O-rich AGB stars.Despite the nova outburst, HM Sge remained enshrouded in dust with no significant dust destruction. The existence of unperturbed dust shell suggests a small influence of the hot component and strong dust shielding from the UV flux. By the use

  4. Concentrations and loads of cadmium, lead, and zinc measured near the peak of the 1999 snowmelt-runoff hydrographs for 42 water-quality stations, Coeur d'Alene River basin, Idaho

    USGS Publications Warehouse

    Woods, Paul F.

    2000-01-01

    The Coeur d’Alene River near Harrison transported 924 pounds of dissolved lead per day, of which 82.8 pounds came from the South Fork and 11.7 pounds from the North Fork. Only 10.2 percent of the load at Harrison was measured at the Pinehurst and Enaville stations; therefore, a substantial load of dissolved lead is being contributed downstream from the confluence of the North and South Forks.

  5. On the link between biomagnetic monitoring and leaf-deposited dust load of urban trees: relationships and spatial variability of different particle size fractions.

    PubMed

    Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Brackx, Melanka; Samson, Roeland

    2014-06-01

    Biomagnetic monitoring of urban tree leaves has proven to be a good estimator of ambient particulate matter. We evaluated its relevancy by determining leaf area normalised weight (mg m(-2)) and SIRM (A) of leaf-deposited particles within three different size fractions (>10 μm, 3-10 μm and 0.2-3 μm) and the SIRM of the leaf-encapsulated particles. Results showed that throughout the in-leaf season, the trees accumulated on average 747 mg m(-2) of dust on their leaves, of which 74 mg m(-2) was within the 0.2-10 μm (∼PM10) size range and 40 mg m(-2) within the 0.2-3 μm (∼PM3) size range. A significant correlation between the SIRM and weight of the surface-deposited particles confirms the potential of biomagnetic monitoring as a proxy for the amount of leaf-deposited particles. Spatial variation of both SIRM and weight throughout the street canyon suggests traffic and wind as key factors for respectively the source and distribution of urban particulates. PMID:24631974

  6. Reprint of On the link between biomagnetic monitoring and leaf-deposited dust load of urban trees: relationships and spatial variability of different particle size fractions.

    PubMed

    Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Brackx, Melanka; Samson, Roeland

    2014-09-01

    Biomagnetic monitoring of urban tree leaves has proven to be a good estimator of ambient particulate matter. We evaluated its relevancy by determining leaf area normalised weight (mg m(-2)) and SIRM (A) of leaf-deposited particles within three different size fractions (>10 μm, 3-10 μm and 0.2-3 μm) and the SIRM of the leaf-encapsulated particles. Results showed that throughout the in-leaf season, the trees accumulated on average 747 mg m(-2) of dust on their leaves, of which 74 mg m(-2) was within the 0.2-10 μm (∼PM10) size range and 40 mg m(-2) within the 0.2-3 μm (∼PM3) size range. A significant correlation between the SIRM and weight of the surface-deposited particles confirms the potential of biomagnetic monitoring as a proxy for the amount of leaf-deposited particles. Spatial variation of both SIRM and weight throughout the street canyon suggests traffic and wind as key factors for respectively the source and distribution of urban particulates. PMID:24890181

  7. Allergies, asthma, and dust

    MedlinePlus

    Allergic rhinitis - dust ... 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 said to have a dust allergy. ...

  8. Prediction of unsteady aerodynamic loadings caused by leading edge and trailing edge control surface motions in subsonic compressible flow: Analysis and results

    NASA Technical Reports Server (NTRS)

    Rowe, W. S.; Redman, M. C.; Ehlers, F. E.; Sebastian, J. D.

    1975-01-01

    A theoretical analysis and computer program was developed for the prediction of unsteady lifting surface loadings caused by motions of leading edge and trailing edge control surfaces having sealed gaps. The final form of the downwash integral equation was formulated by isolating the singularities from the nonsingular terms and using a preferred solution process to remove and evaluate the downwash discontinuities in a systematic manner. Comparisons of theoretical and experimental pressure data are made for several control surface configurations. The comparisons indicate that reasonably accurate theoretical pressure distributions and generalized forces may be obtained for a wide variety of control surface configurations. Spanwise symmetry or antisymmetry of motion, and up to six control surfaces on each half span can be accommodated.

  9. Mineralogical controls on dust emissions in the Bodele Depression, Chad

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface mineralogy is critical in the understanding of aeolian processes, however its role in dust production is currently underestimated. Recent research indicates that discrepancies between predicted and observed dust loads by dust models may be attributed to inadequacies within their associated d...

  10. Newton to Einstein — dust to dust

    SciTech Connect

    Kopp, Michael; Uhlemann, Cora; Haugg, Thomas E-mail: cora.uhlemann@physik.lmu.de

    2014-03-01

    We investigate the relation between the standard Newtonian equations for a pressureless fluid (dust) and the Einstein equations in a double expansion in small scales and small metric perturbations. We find that parts of the Einstein equations can be rewritten as a closed system of two coupled differential equations for the scalar and transverse vector metric perturbations in Poisson gauge. It is then shown that this system is equivalent to the Newtonian system of continuity and Euler equations. Brustein and Riotto (2011) conjectured the equivalence of these systems in the special case where vector perturbations were neglected. We show that this approach does not lead to the Euler equation but to a physically different one with large deviations already in the 1-loop power spectrum. We show that it is also possible to consistently set to zero the vector perturbations which strongly constrains the allowed initial conditions, in particular excluding Gaussian ones such that inclusion of vector perturbations is inevitable in the cosmological context. In addition we derive nonlinear equations for the gravitational slip and tensor perturbations, thereby extending Newtonian gravity of a dust fluid to account for nonlinear light propagation effects and dust-induced gravitational waves.