Heavy metal concentration of settled surface dust in residential building

International Nuclear Information System (INIS)

Nor Aimi abdul Wahab; Fairus Muhamad Darus; Norain Isa; Siti Mariam Sumari; Nur Fatihah Muhamad Hanafi

2012-01-01

The concentrations of heavy metals (Cu, Ni, Pb and Zn) in settled surface dust were collected from nine residential buildings in different areas in Seberang Prai Tengah District, Pulau Pinang. The samples of settled surface dust were collected in 1 m 2 area by using a polyethylene brush and placed in the dust pan by sweeping the living room floor most accessible to the occupants. Heavy metals concentrations were determined by using inductively coupled plasma optical emission spectrometer (ICP-OES) after digestion with nitric acid and sulphuric acid. The results show that the range of heavy metals observed in residential buildings at Seberang Prai Tengah were in the range of 2.20-14.00 mg/ kg, 1.50-32.70 mg/ kg, 1.50-76.80 mg/ kg and 14.60-54.40 mg/ kg for Cu, Ni, Pb and Zn respectively. The heavy metal concentration in the investigated areas followed the order: Pb > Zn > Ni > Cu. Statistical analysis indicates significant correlation between all the possible pairs of heavy metal. The results suggest a likely common source for the heavy metal contamination, which could be traced most probably to vehicular emissions, street dust and other related activities. (author)

Dust acoustic shock wave at high dust density

International Nuclear Information System (INIS)

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

2003-01-01

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

[Dust concentration analysis in non-coal mining. Exposure evaluation based on measurements performed by occupational hygiene laboratories in the years 2001-2005 in Poland].

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Bujak-Pietrek, Stella; Mikołajczyk, Urszula; Szadkowska-Stańczyk, Irena

2011-01-01

Non-coal mining includes the extraction of materials for construction (stone, gravel, sand and clay), chemical industry (salt and sulfur), metallurgy (metal ores, uranium and thorium) and other mining and quarrying. Regardless of the type of mining company one of the most common health hazards in this sector is exposure to high concentrations of dust occurring during the extraction of materials. Such activities as drilling, use of blasting agents, processing of raw material, its transportation and loading are the source of large amounts of dust containing crystalline silica. Data on exposure to dust, collected by industrial hygiene laboratories on the basis of dust concentration measurements in the work environment, were obtained from the sanitary inspection service. The analysis of dust concentrations at workplaces in non-coal mining covered the years 2001-2005. The average concentration of inhalable and respirable dust and the degree of results dispersion at workposts in different branches of non-coal mining (according to NACE rev1.1) were evaluated. Also there was estimated the percentage of surveys indicating dust concentrations above hygiene standards. Almost 5000 measurements of dust concentrations were performed in the years under study. The highest concentration of inhalable dust was noted for the production of salt (5.51 mg/m3), other mining and quarrying (4.30 mg/m3) and quarrying of slate (3.77 mg/m3). For respirable dust the highest concentrations were noted in other mining and quarrying (1.10 mg/m3), quarrying of slate (1.09 mg/m3) and quarrying of stone (0.81 mg/m3). Exposure to high concentrations of dust during the extraction of non-carbon is still an important hazard to human health. Almost for all workposts under study the excess of hygiene standards were observed.

Lead Concentration in Primary School Soil-Dust in Nigeria, Africa

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Ekwumemgbo P. A.

2013-04-01

Full Text Available Lead in soil has been recognized as a public health problem, particularly among children. In recent years, attention has been directed to cumulative adverse effects of lead at low levels of intake. Leadcontaminated soil and dust have been identified as important contributors to blood lead levels. This work examines the total concentration of lead in primary school soil-dust in Nigeria. Soil-dusts were collected randomly from six geopolitical areas of Nigeria, digested and analysed for total lead concentration by Atomic Absorption Spectrophotometry. The mean lead concentration in the dry season for the North East (NE, North West (NW, North Central (NC, South South (SS, South East (SE, South West (SW were 131.60 ± 70.98 mg/kg, 108.04 ± 47.33 mg/kg, 72.94 ± 55.45 mg/kg, 66.14 ± 43.9 mg/kg, 45.98 ± 34.60 mg/kg and 67.98 ± 34.89 mg/kg respectively. In the raining season the mean lead concentration were 130.78 ± 70.80 mg/kg, 106.24 ± 47.02 mg/kg, 70.96 ± 55.52 mg/kg, 64.12 ± 48.00 mg/kg, 44.58 ± 28.90 mg/kg, and 66.26 ± 41.87 mg/kg respectively. This analysis is necessary to provide scientific data base for the loading of lead in classroom soil-dust in each zone. The authors recommend measurement and surveillance of lead blood level of the primary school children and a clean-up of both classrooms and the school environment.

High temperature and dust load in mines

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, V V; Bolonova, L N; Donets, I K; Mukhina, K Sh

1989-02-01

Presents results of study of combined load on the human system of heat and dust as encountered in deep coal mines in the Donbass. Groups of coal miners were studied to ascertain the state of their lungs, particularly the presence of free silica, dust, collagen, etc. The sickness records for a number of Donbass mining associations for the past 25 years were analyzed. Multiple regression analysis of the data obtained led to curves relating the number of shifts worked to dust levels, pulmonary ventilation (0.01 and 0.04 m/sup 3//min) and maximum admissible dust concentrations (2, 4, 6 and 10 mg/m/sup 3/). In the 25-35 C temperature range a rise of 1 C is accompanied by increases of 9.9% in dust mass, 15.4% in silica content, 10.7% in mineral impurities and 2.3% in pathomorphological changes in the lungs. An adjustment to the maximum admissible concentration correction coefficient of 10% for every 1 C over 26 C is recommended. 1 ref.

Effect of ecological restoration programs on dust concentrations in the North China Plain: a case study

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Long, Xin; Tie, Xuexi; Li, Guohui; Cao, Junji; Feng, Tian; Zhao, Shuyu; Xing, Li; An, Zhisheng

2018-05-01

In recent decades, the Chinese government has made a great effort in initiating large-scale ecological restoration programs (ERPs) to reduce the dust concentrations in China, especially for dust storm episodes. Using the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product, the ERP-induced land cover changes are quantitatively evaluated in this study. Two obvious vegetation protective barriers arise throughout China from the southwest to the northeast, which are well known as the Green Great Wall (GGW). Both the grass GGW and forest GGW are located between the dust source region (DSR) and the densely populated North China Plain (NCP). To assess the effect of ERPs on dust concentrations, a regional transport/dust model (WRF-DUST, Weather Research and Forecast model with dust) is applied to investigate the evolution of dust plumes during a strong dust storm episode from 2 to 8 March 2016. The WRF-DUST model generally performs reasonably well in reproducing the temporal variations and spatial distributions of near-surface [PMC] (mass concentration of particulate matter with aerodynamic diameter between 2.5 and 10 µm) during the dust storm event. Sensitivity experiments have indicated that the ERP-induced GGWs help to reduce the dust concentration in the NCP, especially in BTH (Beijing, Tianjin, and Hebei). When the dust storm is transported from the upwind DSR to the downwind NCP, the [PMC] reduction ranges from -5 to -15 % in the NCP, with a maximum reduction of -12.4 % (-19.2 µg m-3) in BTH and -7.6 % (-10.1 µg m-3) in the NCP. We find the dust plumes move up to the upper atmosphere and are transported from the upwind DSR to the downwind NCP, accompanied by dust decrease. During the episode, the forest GGW is nonsignificant in dust concentration control because it is of benefit for dry deposition and not for emission. Conversely, the grass GGW is beneficial in controlling dust erosion and is the dominant reason for [PMC] decrease in the NCP

Effect of ecological restoration programs on dust concentrations in the North China Plain: a case study

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X. Long

2018-05-01

Full Text Available In recent decades, the Chinese government has made a great effort in initiating large-scale ecological restoration programs (ERPs to reduce the dust concentrations in China, especially for dust storm episodes. Using the Moderate Resolution Imaging Spectroradiometer (MODIS land cover product, the ERP-induced land cover changes are quantitatively evaluated in this study. Two obvious vegetation protective barriers arise throughout China from the southwest to the northeast, which are well known as the Green Great Wall (GGW. Both the grass GGW and forest GGW are located between the dust source region (DSR and the densely populated North China Plain (NCP. To assess the effect of ERPs on dust concentrations, a regional transport/dust model (WRF-DUST, Weather Research and Forecast model with dust is applied to investigate the evolution of dust plumes during a strong dust storm episode from 2 to 8 March 2016. The WRF-DUST model generally performs reasonably well in reproducing the temporal variations and spatial distributions of near-surface [PMC] (mass concentration of particulate matter with aerodynamic diameter between 2.5 and 10 µm during the dust storm event. Sensitivity experiments have indicated that the ERP-induced GGWs help to reduce the dust concentration in the NCP, especially in BTH (Beijing, Tianjin, and Hebei. When the dust storm is transported from the upwind DSR to the downwind NCP, the [PMC] reduction ranges from −5 to −15 % in the NCP, with a maximum reduction of −12.4 % (−19.2 µg m−3 in BTH and −7.6 % (−10.1 µg m−3 in the NCP. We find the dust plumes move up to the upper atmosphere and are transported from the upwind DSR to the downwind NCP, accompanied by dust decrease. During the episode, the forest GGW is nonsignificant in dust concentration control because it is of benefit for dry deposition and not for emission. Conversely, the grass GGW is beneficial in controlling dust erosion and is the

Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

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Sai-Chun Tan

Full Text Available A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the 50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36. These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

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

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J. O. Olowoyo

2016-01-01

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

African Dust Transport Captured by Rare Earth Elemental Concentrations in Coral Microatolls

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Ouellette, G., Jr.; DeLong, K.; Herrmann, A.; Huang, C. Y.; Shen, C. C.

2017-12-01

Winds are integral components of the climate system; unfortunately, windsare also among the climate variables that are most difficult to study prior to the instrumentalrecord. Paleoclimatologists use sedimentary dust records (e.g., lake and ocean cores) tounderstand past wind circulation conditions; however, these types of records typically are notamenable to sub-annual interpretation due to their limited temporal resolution. Here wedeveloped a coral-based dust-wind proxy to overcome these temporal limitations by usingtrace (nmol/mol) rare earth elemental concentrations recorded in the skeletons of coralmicroatolls. The rare earth elements (REE; the lanthanides as well as scandium and yttrium)behave similarly in geologic and geochemical systems, and have served as useful proxies ofgeological processes in both deep and shallow time. Corals incorporate REE as they deposittheir exoskeletons that extend incrementally with time forming annual density band couplets.Coral microatolls grow at or near the sea surface, where coral REE concentrations are mostsensitive to dust deposition. Our study site off the west coast of Haiti is down stream of light-REE depleted bedrock whereas REE in African dust, transported by the easterly trade winds,reflect average crustal abundances. This unique "upstream" source signature allows forterrestrial contamination of the dust-wind signal to be ruled out. Light REE concentrations (esp.Nd and Pr) demonstrate an order of magnitude increase within coral aragonite coincident withmajor African dust plume events throughout the past decade, with Nd/Ca and Pr/Ca increasingfrom an average of 27 nmol/mol to an average 144 nmol/mol and an average of 5 nmol/mol toan average of 37 nmol/mol, respectively, during major African dust plume events. Monthly-resolved REE analysis shows these REE peaks coincide with the summer dust season rather thanHaiti's two wet seasons in spring and autumn. Regression of our coral REE dust proxy tosatellite records of

The evaluation and quantification of respirable coal and silica dust concentrations: a task-based approach.

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Grové, T; Van Dyk, T; Franken, A; Du Plessis, J

2014-01-01

Silicosis and coal worker's pneumoconiosis are serious occupational respiratory diseases associated with the coal mining industry and the inhalation of respirable dusts containing crystalline silica. The purpose of this study (funded by the Mine Health and Safety Council of South Africa) was to evaluate the individual contributions of underground coal mining tasks to the respirable dust and respirable silica dust concentrations in an underground section by sampling the respirable dust concentrations at the intake and return of each task. The identified tasks were continuous miner (CM) cutting, construction, transfer of coal, tipping, and roof bolting. The respirable dust-generating hierarchy of the tasks from highest to lowest was: transfer of coal > CM right cutting > CM left cutting > CM face cutting > construction > roof bolting > tipping; and for respirable silica dust: CM left cutting > construction > transfer of coal > CM right cutting. Personal exposure levels were determined by sampling the exposures of workers performing tasks in the section. Respirable dust concentrations and low concentrations of respirable silica dust were found at the intake air side of the section, indicating that air entering the section is already contaminated. The hierarchy for personal respirable dust exposures was as follows, from highest to lowest: CM operator > cable handler > miner > roof bolt operator > shuttle car operator, and for respirable silica dust: shuttle car operator > CM operator > cable handler > roof bolt operator > miner. Dust control methods to lower exposures should include revision of the position of workers with regard to the task performed, positioning of the tasks with regard to the CM cutting, and proper use of the line curtains to direct ventilation appropriately. The correct use of respiratory protection should also be encouraged.

Concentrations and size distribution of inhalable and respirable dust among sugar industry workers: a pilot study in Khon Kaen, Thailand.

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Sakunkoo, Pornpun; Chaiear, Naesinee; Chaikittiporn, Chalermchai; Sadhra, Steven

2011-11-01

There has been very limited information regarding bagasse exposure among workers in sugar industries as well as on health outcomes. The authors determined the occupational exposure of sugar industry workers in Khon Kaen to airborne bagasse dust. The size of the bagasse dust ranged from 0.08 to 9 µm with the highest size concentration of 2.1 to 4.7 µm. The most common size had a geometric mean diameter of 5.2 µm, with a mass concentration of 6.89 mg/m(3)/log µm. The highest mean values of inhalable and respirable dust were found to be 9.29 mg/m(3) from February to April in bagasse storage, 5.12 mg/m(3) from May to September, and 4.12 mg/m(3) from October to January. Inhalable dust concentrations were 0.33, 0.47, and 0.41 mg/m(3), respectively. Workers are likely to be exposed to high concentrations of bagasse dust and are at risk of respiratory diseases. Preventive measures, both in the form of engineering designs and personal protective devices, should be implemented.

High-latitude dust in the Earth system

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Bullard, Joanna E; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert; NcKenna Neuman, Cheryl; Mockford, Tom; Stewart, Helena; Thorsteinsson, Throstur

2016-01-01

Natural dust is often associated with hot, subtropical deserts, but significant dust events have been reported from cold, high latitudes. This review synthesizes current understanding of high-latitude (≥50°N and ≥40°S) dust source geography and dynamics and provides a prospectus for future research on the topic. Although the fundamental processes controlling aeolian dust emissions in high latitudes are essentially the same as in temperate regions, there are additional processes specific to or enhanced in cold regions. These include low temperatures, humidity, strong winds, permafrost and niveo-aeolian processes all of which can affect the efficiency of dust emission and distribution of sediments. Dust deposition at high latitudes can provide nutrients to the marine system, specifically by contributing iron to high-nutrient, low-chlorophyll oceans; it also affects ice albedo and melt rates. There have been no attempts to quantify systematically the expanse, characteristics, or dynamics of high-latitude dust sources. To address this, we identify and compare the main sources and drivers of dust emissions in the Northern (Alaska, Canada, Greenland, and Iceland) and Southern (Antarctica, New Zealand, and Patagonia) Hemispheres. The scarcity of year-round observations and limitations of satellite remote sensing data at high latitudes are discussed. It is estimated that under contemporary conditions high-latitude sources cover >500,000 km2 and contribute at least 80–100 Tg yr−1 of dust to the Earth system (~5% of the global dust budget); both are projected to increase under future climate change scenarios.

High Latitude Dust in the Earth System

Science.gov (United States)

Bullard, Joanna E.; Baddock, Matthew; Bradwell, Tom; Crusius, John; Darlington, Eleanor; Gaiero, Diego; Gasso, Santiago; Gisladottir, Gudrun; Hodgkins, Richard; McCulloch, Robert;

Influence of radon-daughter exposure rate and uranium ore dust concentration on occurrence of lung tumors

International Nuclear Information System (INIS)

Cross, F.T.; Palmer, R.F.; Busch, R.H.

1980-01-01

Groups of male SPF Wistar rats were exposed concurrently to several levels of radon daughters and uranium ore dust to study the effect of these variables on pulmonary disease states. Clinical pathology data at 1 yr postexposure indicate no significant differences among exposed animals when compared with controls. Preliminary histopathologic data suggest a trend toward increasing lung tumor risk as the exposure rate is decreased (constant total dose), but the differences are not statistically significant at the 0.05 level. A similar trend occurs with decrease in ore dust concentration (except for the 2560-WLM exposure group), but these differences are also not significant at the 0.05 level. The tumor risk is significantly (0.05 level) increased as the exposure level increases from approximately 320 and 640 WLM to 2560 WLM at the high ore dust concentration

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

Science.gov (United States)

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

2017-06-01

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

Modeling of surface dust concentrations using neural networks and kriging

Science.gov (United States)

Buevich, Alexander G.; Medvedev, Alexander N.; Sergeev, Alexander P.; Tarasov, Dmitry A.; Shichkin, Andrey V.; Sergeeva, Marina V.; Atanasova, T. B.

2016-12-01

Creating models which are able to accurately predict the distribution of pollutants based on a limited set of input data is an important task in environmental studies. In the paper two neural approaches: (multilayer perceptron (MLP)) and generalized regression neural network (GRNN)), and two geostatistical approaches: (kriging and cokriging), are using for modeling and forecasting of dust concentrations in snow cover. The area of study is under the influence of dust emissions from a copper quarry and a several industrial companies. The comparison of two mentioned approaches is conducted. Three indices are used as the indicators of the models accuracy: the mean absolute error (MAE), root mean square error (RMSE) and relative root mean square error (RRMSE). Models based on artificial neural networks (ANN) have shown better accuracy. When considering all indices, the most precision model was the GRNN, which uses as input parameters for modeling the coordinates of sampling points and the distance to the probable emissions source. The results of work confirm that trained ANN may be more suitable tool for modeling of dust concentrations in snow cover.

Evaluating Ice Nucleating Particle Concentrations From Prognostic Dust Minerals in an Earth System Model

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

2016-12-01

The effect of aerosol particles on the radiative properties of clouds, the so-called, indirect effect of aerosols, is recognized as one of the largest sources of uncertainty in climate prediction. The distribution of water vapor, precipitation, and ice cloud formation are influenced by the atmospheric ice formation, thereby modulating cloud albedo and thus climate. It is well known that different particle types possess different ice formation propensities with mineral dust being a superior ice nucleating particle (INP) compared to soot particles. Furthermore, some dust mineral types are more proficient INP than others, depending on temperature and relative humidity.In recent work, we have presented an improved dust aerosol module in the NASA GISS Earth System ModelE2 with prognostic mineral composition of the dust aerosols. Thus, there are regional variations in dust composition. We evaluated the predicted mineral fractions of dust aerosols by comparing them to measurements from a compilation of about 60 published literature references. Additionally, the capability of the model to reproduce the elemental composition of the simulated dusthas been tested at Izana Observatory at Tenerife, Canary Islands, which is located off-shore of Africa and where frequent dust events are observed. We have been able to show that the new approach delivers a robust improvement of the predicted mineral fractions and elemental composition of dust.In the current study, we use three-dimensional dust mineral fields and thermodynamic conditions, which are simulated using GISS ModelE, to calculate offline the INP concentrations derived using different ice nucleation parameterizations that are currently discussed. We evaluate the calculated INP concentrations from the different parameterizations by comparing them to INP concentrations from field measurements.

Recirculation of Chilean copper smelting dust with high impurities contents to the smelting process

Energy Technology Data Exchange (ETDEWEB)

Sano, H.; Fujisawa, T. [Nagoya Univ., Nagoya (Japan). EcoTopia Science Inst.; Montenegro, V. [Nagoya Univ., Nagoya (Japan). Dept. of Materials Science and Engineering

2007-07-01

Dust generated during the copper smelting process is generally stabilized using hydrometallurgical methods as it contains high concentrations of arsenic. In this laboratory study, dust was recirculated during the smelting process in order to recover more copper and decrease dust emissions while recovering more copper. The behaviour of impurities and their influence on matte quality was also investigated. Industrial matte, flue dust, slag, and copper concentrates from a Chilean smelter were used as test materials. Dust recirculation tests were conducted in a simulated electric furnace. Off-gases were collected in a reaction tube, and the condensed volatile matter, slag, and matte phases were analyzed for their elemental content by inductively coupled plasma atomic emission spectrometry. The distribution of arsenic (As); antimony (Sb), bismuth (Bi), lead (Pb), and zinc (Zn) were investigated by varying the amounts of dust recirculating to the smelting stage with 21 per cent of the oxygen. Results showed that distributions of all analyzed elements increased with recirculation. It was concluded that copper can be recovered using the dust recirculation technique. However, impurities may limit the efficacy of the dust recirculation process. 6 refs., 3 tabs., 4 figs.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

High levels of antimony in dust from e-waste recycling in southeastern China

International Nuclear Information System (INIS)

Bi, Xiangyang; Li, Zhonggen; Zhuang, Xiaochun; Han, Zhixuan; Yang, Wenlin

2011-01-01

Environmental contamination due to uncontrolled e-waste recycling is an emerging global issue. Antimony (Sb) is a toxic element used in semiconductor components and flame retardants for circuit board within electronic equipment. When e-waste is recycled, Sb is released and contaminates the surrounding environment; however, few studies have characterized the extent of this problem. In this study, we investigated Sb and arsenic (As) distributions in indoor dust from 13 e-waste recycling villages in Guiyu, Guangdong Province, southeastern China. Results revealed significantly elevated concentrations of Sb (6.1-232 mg/kg) in dust within all villages, which were 3.9-147 times higher than those from the non e-waste sites, indicating e-waste recycling was an important source of Sb pollution. On the contrary, As concentrations (5.4-17.7 mg/kg) in e-waste dusts were similar to reference values from the control sites. Therefore, dusts emitted from e-waste recycling may be characterized by high Sb/As ratios, which may help identify the contamination due to the e-waste recycling activities. - Highlights: → Antimony and arsenic concentrations in dust from e-waste recycling were investigated. → E-waste recycling is an important emerging source of Sb pollution. → Sb/As ratios may help identify the e-waste contamination.

High levels of antimony in dust from e-waste recycling in southeastern China

Energy Technology Data Exchange (ETDEWEB)

Bi, Xiangyang, E-mail: bixy@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); Faculty of Earth Science, China University of Geosciences, Wuhan 430074 (China); Li, Zhonggen [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Zhuang, Xiaochun [Faculty of Materials Science and Chemical Engineering, China University of Geosciences, Wuhan 430074 (China); Han, Zhixuan [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); Faculty of Earth Science, China University of Geosciences, Wuhan 430074 (China); Yang, Wenlin [Faculty of Earth Science, China University of Geosciences, Wuhan 430074 (China)

2011-11-01

Environmental contamination due to uncontrolled e-waste recycling is an emerging global issue. Antimony (Sb) is a toxic element used in semiconductor components and flame retardants for circuit board within electronic equipment. When e-waste is recycled, Sb is released and contaminates the surrounding environment; however, few studies have characterized the extent of this problem. In this study, we investigated Sb and arsenic (As) distributions in indoor dust from 13 e-waste recycling villages in Guiyu, Guangdong Province, southeastern China. Results revealed significantly elevated concentrations of Sb (6.1-232 mg/kg) in dust within all villages, which were 3.9-147 times higher than those from the non e-waste sites, indicating e-waste recycling was an important source of Sb pollution. On the contrary, As concentrations (5.4-17.7 mg/kg) in e-waste dusts were similar to reference values from the control sites. Therefore, dusts emitted from e-waste recycling may be characterized by high Sb/As ratios, which may help identify the contamination due to the e-waste recycling activities. - Highlights: {yields} Antimony and arsenic concentrations in dust from e-waste recycling were investigated. {yields} E-waste recycling is an important emerging source of Sb pollution. {yields} Sb/As ratios may help identify the e-waste contamination.

The role of dust storms in total atmospheric particle concentrations at two sites in the western U.S.

Science.gov (United States)

Neff, Jason C.; Reynolds, Richard L.; Munson, Seth M.; Fernandez, Daniel; Belnap, Jayne

2013-01-01

Mineral aerosols are produced during the erosion of soils by wind and are a common source of particles (dust) in arid and semiarid regions. The size of these particles varies widely from less than 2 µm to larger particles that can exceed 50 µm in diameter. In this study, we present two continuous records of total suspended particle (TSP) concentrations at sites in Mesa Verde and Canyonlands National Parks in Colorado and Utah, USA, respectively, and compare those values to measurements of fine and coarse particle concentrations made from nearby samplers. Average annual concentrations of TSP at Mesa Verde were 90 µg m−3 in 2011 and at Canyonlands were 171 µg m−3 in 2009, 113 µg m−3 in 2010, and 134 µg m−3 in 2011. In comparison, annual concentrations of fine (diameter of 2.5 µm and below) and coarse (2.5–10 µm diameter) particles at these sites were below 10 µg m−3 in all years. The high concentrations of TSP appear to be the result of regional dust storms with elevated concentrations of particles greater than 10 µm in diameter. These conditions regularly occur from spring through fall with 2 week mean TSP periodically in excess of 200 µg m−3. Measurement of particles on filters indicates that the median particle size varies between approximately 10 µm in winter and 40 µm during the spring. These persistently elevated concentrations of large particles indicate that regional dust emission as dust storms and events are important determinants of air quality in this region.

Experimental human exposure to inhaled grain dust and ammonia: towards a model of concentrated animal feeding operations.

Science.gov (United States)

Sigurdarson, Sigurdur T; O'Shaughnessy, Patrick T; Watt, Janet A; Kline, Joel N

2004-10-01

Ammonia and endotoxin-rich dust are present in high concentrations in swine confinement facilities; exposure to this environment is linked to workers' respiratory problems. We hypothesized that experimental exposure to ammonia and dust would impair pulmonary function, and that these exposures would be synergistic. We exposed six normal subjects and eight subjects with mild asthma to ammonia (16-25 ppm) and/or endotoxin-rich grain dust (4 mg/m3). Pulmonary function and exhaled NOx were measured before and after exposure. There was no significant change in pulmonary function in the normal subjects following any of the exposure conditions. Among asthmatics, a significant transient decrease in FEV1 was induced by grain dust, but was not altered by ammonia; increased bronchial hyperreactivity was also noted in this group. In a vulnerable population, exposure to grain dust results in transient airflow obstruction. Short-term exposure to ammonia does not increase this response.

The effect of mineral dust transport on PM10 concentrations and physical properties in Istanbul during 2007-2014

Science.gov (United States)

Flores, Rosa M.; Kaya, Nefel; Eşer, Övgü; Saltan, Şehnaz

2017-11-01

Mineral dust is the most significant source of natural particulate matter. In urban regions, where > 50% of the world population is currently living, local emissions of particulate matter are further aggravated by mineral dust loadings from deserts. The megacity of Istanbul is located in an area sensitive to local pollution due to transportation (i.e., private cars, public transportation, aircrafts, ships, heavy diesel trucks, etc.), industrial emissions, residential heating, and long-range transport from Europe, Asia, and deserts. In this work, the effect of desert dust transport on PM10 concentrations and physical properties was investigated for the period of 2007-2014 in the touristic area of Aksaray, Istanbul. The Dust Regional Atmospheric Model (DREAM8b) was used to predict dust loading in Istanbul during dust transport events. Variations on surface PM10 concentrations were investigated according to seasons and during dust transport events. Cluster analysis of air mass backward trajectories was useful to understand frequency analysis and air mass trajectory dependence of PM10 concentrations on dust loadings. The effect of desert dust transport on aerosol optical depths was also investigated. It was observed that PM10 concentrations exceeded the air quality standard of 50 μg m- 3 50% of the time during the study period. The largest number of exceedances in air quality standard occurred during the spring and winter seasons. Approximately 40-60% of the dust loading occurs during the spring. Desert dust and non-desert dust sources contribute to 22-72% and 48-81% of the ground-level PM10 concentrations in Aksaray, Istanbul during the study period. Averaged AOD observed during dust transport events in spring and summer ranged 0.35-0.55. Cluster analysis resolved over 82% the variability of individual air mass backward trajectories into 5 clusters. Overall, air masses arriving to Istanbul at 500 m are equally distributed into northern (52%) and southern (48

Variations in airborne bacterial communities at high altitudes over the Noto Peninsula (Japan) in response to Asian dust events

Science.gov (United States)

Maki, Teruya; Hara, Kazutaka; Iwata, Ayumu; Lee, Kevin C.; Kawai, Kei; Kai, Kenji; Kobayashi, Fumihisa; Pointing, Stephen B.; Archer, Stephen; Hasegawa, Hiroshi; Iwasaka, Yasunobu

2017-10-01

Aerosol particles, including airborne microorganisms, are transported through the free troposphere from the Asian continental area to the downwind area in East Asia and can influence climate changes, ecosystem dynamics, and human health. However, the variations present in airborne bacterial communities in the free troposphere over downwind areas are poorly understood, and there are few studies that provide an in-depth examination of the effects of long-range transport of aerosols (natural and anthropogenic particles) on bacterial variations. In this study, the vertical distributions of airborne bacterial communities at high altitudes were investigated and the bacterial variations were compared between dust events and non-dust events.Aerosols were collected at three altitudes from ground level to the free troposphere (upper level: 3000 or 2500 m; middle level: 1200 or 500 m; and low level: 10 m) during Asian dust events and non-dust events over the Noto Peninsula, Japan, where westerly winds carry aerosols from the Asian continental areas. During Asian dust events, air masses at high altitudes were transported from the Asian continental area by westerly winds, and laser imaging detection and ranging (lidar) data indicated high concentrations of non-spherical particles, suggesting that dust-sand particles were transported from the central desert regions of Asia. The air samples collected during the dust events contained 10-100 times higher concentrations of microscopic fluorescent particles and optical particle counter (OPC) measured particles than in non-dust events. The air masses of non-dust events contained lower amounts of dust-sand particles. Additionally, some air samples showed relatively high levels of black carbon, which were likely transported from the Asian continental coasts. Moreover, during the dust events, microbial particles at altitudes of > 1200 m increased to the concentrations ranging from 1. 2 × 106 to 6. 6 × 106 particles m-3. In contrast

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

International Nuclear Information System (INIS)

Simon, Edina; Braun, Mihaly; Vidic, Andreas; Bogyo, David; Fabian, Istvan; Tothmeresz, Bela

2011-01-01

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. - Highlights: → We studied the elements in dust and leaves along an urbanization gradient, Austria. → We analysed 19 elements: Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Na, P, Pb, S, Sr and Zn. → Elemental concentrations were higher in urban area than in the rural area. → Studied areas were separated by CDA based on the elemental concentrations. → Dust and leaves can be useful for monitoring the environmental load. - Studying the elements (Al, Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, Zn) in dust and leaves along an urbanization gradient in Wien, Austria we found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for Al, Ba, Fe, Pb, P and Se, and concentrations of leaves were significantly higher in urban than in rural area for Mn and Sr.

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

Energy Technology Data Exchange (ETDEWEB)

Simon, Edina, E-mail: edina.simon@gmail.com [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Braun, Mihaly [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Vidic, Andreas [Department fuer Naturschutzbiologie, Vegetations- und Landschaftsoekologie, Universitat Wien, Althanstrasse 14, 1090 Wien (Austria); Bogyo, David [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Fabian, Istvan [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Tothmeresz, Bela [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary)

2011-05-15

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. - Highlights: > We studied the elements in dust and leaves along an urbanization gradient, Austria. > We analysed 19 elements: Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Na, P, Pb, S, Sr and Zn. > Elemental concentrations were higher in urban area than in the rural area. > Studied areas were separated by CDA based on the elemental concentrations. > Dust and leaves can be useful for monitoring the environmental load. - Studying the elements (Al, Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, Zn) in dust and leaves along an urbanization gradient in Wien, Austria we found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for Al, Ba, Fe, Pb, P and Se, and concentrations of leaves were significantly higher in urban than in rural area for Mn and Sr.

β Absorption dust concentration monitor system based on the PLC

International Nuclear Information System (INIS)

Lian Dexing; Zhou Xiuliang; Liu Liyan; Li Zonglun; Cao Guanghui; Mao Wanchong

2011-01-01

To provide an on-line automatic system for dust concentration monitor is the purpose of this design.The system based on β-ray-absorption-method,employing PLC (Programmable Logic Controller) control technology, is presented. The user input parameter setup,the data acquisition and processing, and the communication with computer can be effectively regulated using the advanced PLC control technology. It has the features of high reliability, easy operation and easy maintenance, and the ability to monitor remotely. Measurement range: 0.1-1500 mg/m 3 , Accuracy: ±9%. The structure,working principle, electric circuit and software development of the system are introduced in detail. (authors)

Prototype detector development for measurement of high altitude Martian dust using a future orbiter platform

Science.gov (United States)

Pabari, Jayesh; Patel, Darshil; Chokhawala, Vimmi; Bogavelly, Anvesh

2016-07-01

Dust devils mostly occur during the mid of Southern hemisphere summer on Mars and play a key role in the background dust opacity. Due to continuous bombardment of micrometeorites, secondary ejecta come out from the Moons of the Mars and can easily escape. This phenomenon can contribute dust around the Moons and therefore, also around the Mars. Similar to the Moons of the Earth, the surfaces of the Martian Moons get charged and cause the dust levitation to occur, adding to the possible dust source. Also, interplanetary dust particles may be able to reach the Mars and contribute further. It is hypothesized that the high altitude Martian dust could be in the form of a ring or tori around the Mars. However, no such rings have been detected to the present day. Typically, width and height of the dust torus is ~5 Mars radii wide (~16950 km) in both the planes as reported in the literature. Recently, very high altitude dust at about 1000 km has been found by MAVEN mission and it is expected that the dust may be concentrated at about 150 to 500 km. However, a langmuir probe cannot explain the source of such dust particles. It is a puzzling question to the space scientist how dust has reached to such high altitudes. A dedicated dust instrument on future Mars orbiter may be helpful to address such issues. To study origin, abundance, distribution and seasonal variation of Martian dust, a Mars Orbit Dust Experiment (MODEX) is proposed. In order to measure the Martian dust from a future orbiter, design of a prototype of an impact ionization dust detector has been initiated at PRL. This paper presents developmental aspects of the prototype dust detector and initial results. The further work is underway.

Quantitative detection of mass concentration of sand-dust storms via wind-profiling radar and analysis of Z- M relationship

Science.gov (United States)

Wang, Minzhong; Ming, Hu; Ruan, Zheng; Gao, Lianhui; Yang, Di

2018-02-01

With the aim to achieve quantitative monitoring of sand-dust storms in real time, wind-profiling radar is applied to monitor and study the process of four sand-dust storms in the Tazhong area of the Taklimakan Desert. Through evaluation and analysis of the spatial-temporal distribution of reflectivity factor, it is found that reflectivity factor ranges from 2 to 18 dBz under sand-dust storm weather. Using echo power spectrum of radar vertical beams, sand-dust particle spectrum and sand-dust mass concentration at the altitude of 600 ˜ 1500 m are retrieved. This study shows that sand-dust mass concentration reaches 700 μg/m3 under blowing sand weather, 2000 μg/m3 under sand-dust storm weather, and 400 μg/m3 under floating dust weather. The following equations are established to represent the relationship between the reflectivity factor and sand-dust mass concentration: Z = 20713.5 M 0.995 under floating dust weather, Z = 22988.3 M 1.006 under blowing sand weather, and Z = 24584.2 M 1.013 under sand-dust storm weather. The retrieval results from this paper are almost consistent with previous monitoring results achieved by former researchers; thus, it is implied that wind-profiling radar can be used as a new reference device to quantitatively monitor sand-dust storms.

Concentrations of polychlorinated biphenyls in soil and indoor dust associated with electricity generation facilities in Lagos, Nigeria.

Science.gov (United States)

Folarin, Bilikis Temitope; Abdallah, Mohamed Abou-Elwafa; Oluseyi, Temilola; Olayinka, Kehinde; Harrad, Stuart

2018-09-01

Concentrations of 7 indicator polychlorinated biphenyls (PCBs) were measured in dust and soil samples from 12 power stations collected over the two major seasons of the Nigerian climate. Median ƩPCB 7 concentrations in soil ranged from 2 ng/g for power station A to 220 ng/g for power station I; while those in dust ranged from 21 ng/g for power station L to 2200 ng/g for power station I. For individual congeners, median PCB concentrations ranged from 3.8 ng/g for PCB 101 to 52 ng/g for PCB 180 in dust, and  transmission > distribution). Congener patterns in dust and soil samples were compared using principal component analysis (PCA) with those in transformer oil samples from 3 of the power stations studied and with common PCB mixtures (Aroclors). This revealed congener patterns in soil were more closely related to that in the transformer oil than dust. Congener patterns in most samples were similar to Aroclor 1260. Concentrations of PCBs in soil samples close to the transformers significantly exceeded those in soil sampled further away. Copyright © 2018 Elsevier Ltd. All rights reserved.

Windows pollution problems of the dust concentration measurement based on scattering method

International Nuclear Information System (INIS)

Zhao Yanjun; Zhang Yongtao; Shi Xinyue; Xu Chuanlong; Wang Shimin

2009-01-01

The windows are separated the measurement system from the dust space in the light Scattering dust concentration measurement system. The windows are polluted unavoidably by the dust and the measurement error is produced. Based on the Mie Scattering theory, the measurement error is researched in this paper. The numerical simulation results show that the measurement error is related to the particles diameter distribution and the refractive index, but is independent of the particles average diameter. A novel photoelectricity sensor is developed in this paper in order to solve the measurement error by the windows pollution. The calculated method is brought out which can amend the measurement errors by the windows pollution and improve the measurement accuracy.

Quasar Winds as Dust Factories at High Redshift

OpenAIRE

Elvis, Martin; Marengo, Massimo; Karovska, Margarita

2003-01-01

Winds from AGN and quasars will form large amounts of dust, as the cool gas in these winds passes through the (pressure, temperature) region where dust is formed in AGB stars. Conditions in the gas are benign to dust at these radii. As a result quasar winds may be a major source of dust at high redshifts, obviating a difficulty with current observations, and requiring far less dust to exist at early epochs.

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna.

Science.gov (United States)

Simon, Edina; Braun, Mihály; Vidic, Andreas; Bogyó, Dávid; Fábián, István; Tóthmérész, Béla

2011-05-01

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. Copyright © 2011 Elsevier Ltd. All rights reserved.

The concentration, source and deposition flux of ammonium and nitrate in atmospheric particles during dust events at a coastal site in northern China

Science.gov (United States)

Qi, Jianhua; Liu, Xiaohuan; Yao, Xiaohong; Zhang, Ruifeng; Chen, Xiaojing; Lin, Xuehui; Gao, Huiwang; Liu, Ruhai

2018-01-01

Asian dust has been reported to carry anthropogenic reactive nitrogen during transport from source areas to the oceans. In this study, we attempted to characterize NH4+ and NO3- in atmospheric particles collected at a coastal site in northern China during spring dust events from 2008 to 2011. Based on the mass concentrations of NH4+ and NO3- in each total suspended particle (TSP) sample, the samples can be classified into increasing or decreasing types. In Category 1, the concentrations of NH4+ and NO3- were 20-440 % higher in dust day samples relative to samples collected immediately before or after a dust event. These concentrations decreased by 10-75 % in the dust day samples in Categories 2 and 3. Back trajectory analysis suggested that multiple factors, such as the transport distance prior to the reception site, the mixing layer depth on the transport route and the residence time across highly polluted regions, might affect the concentrations of NH4+ and NO3-. NH4+ in the dust day samples was likely either in the form of ammonium salts existing separately to dust aerosols or as the residual of incomplete reactions between ammonium salts and carbonate salts. NO3- in the dust day samples was attributed to various formation processes during the long-range transport. The positive matrix factorization (PMF) receptor model results showed that the contribution of soil dust increased from 23 to 36 % on dust days, with decreasing contributions from local anthropogenic inputs and associated secondary aerosols. The estimated deposition flux of NNH4++NO3- varied greatly from event to event; e.g., the dry deposition flux of NNH4++NO3- increased by 9-285 % in Category 1 but decreased by 46-73 % in Category 2. In Category 3, the average dry deposition fluxes of particulate nitrate and ammonium decreased by 46 % and increased by 10 %, respectively, leading to 11-48 % decrease in the fluxes of NNH4++NO3-.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Dust radiative forcing in snow of the Upper Colorado River Basin: 1. A 6 year record of energy balance, radiation, and dust concentrations

Science.gov (United States)

Painter, Thomas H.; Skiles, S. Mckenzie; Deems, Jeffrey S.; Bryant, Ann C.; Landry, Christopher C.

2012-07-01

Dust in snow accelerates snowmelt through its direct reduction of snow albedo and its further indirect reduction of albedo by accelerating the growth of snow grains. Since the westward expansion of the United States that began in the mid-19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading, largely from the Colorado Plateau and Great Basin. Radiative forcing of snowmelt by dust is not captured by conventional micrometeorological measurements, and must be monitored by a more comprehensive suite of radiation instruments. Here we present a 6 year record of energy balance and detailed radiation measurements in the Senator Beck Basin Study Area, San Juan Mountains, Colorado, USA. Data include broadband irradiance, filtered irradiance, broadband reflected flux, filtered reflected flux, broadband and visible albedo, longwave irradiance, wind speed, relative humidity, and air temperatures. The gradient of the snow surface is monitored weekly and used to correct albedo measurements for geometric effects. The snow is sampled weekly for dust concentrations in plots immediately adjacent to each tower over the melt season. Broadband albedo in the last weeks of snow cover ranged from 0.33 to 0.55 across the 6 years and two sites. Total end of year dust concentration in the top 3 cm of the snow column ranged from 0.23 mg g-1 to 4.16 mg g-1. These measurements enable monitoring and modeling of dust and climate-driven snowmelt forcings in the Upper Colorado River Basin.

Measuring instrument for the determination of dust concentrations. [air filter with. beta. radiometric gage

Energy Technology Data Exchange (ETDEWEB)

Dresia, H; Spohr, F

1975-05-22

The measuring instrument enables a continuous determination of the dust concentration or total dust content in gases on the basis of the radiometric mass determination of dusts. The partial current method is employed, with the gas fetched through a filter cell with a topped intake by a suction pump. A filter band to take up the dust deposit is continuously driven through the filter cell. The filter point and the measuring point with a ..beta..-radionuclide and a detector are both inside the filter cell. The filter cell is sealed all around, at the entrance and exit of the filter band. The band itself acts as a seal. The filter band also has borders strengthened with, e.g., plastic strips which engage the drive. The widths of the slits are adjustable in height.

The effects of a newsletter on bedding control on house dust mite allergen concentrations in childcare centers in Korea

Directory of Open Access Journals (Sweden)

Jeonghoon Kim

2015-08-01

Full Text Available Objectives Bedding in childcare centers (CCCs can hold house dust mite (HDM allergens. This study examined whether HDM allergen levels can be reduced through the distribution of an educational newsletter on bedding control to parents of CCC children in Korea. Methods All 38 CCCs were measured for Der 1 (sum of Der f 1 and Der p 1 concentrations on classroom floors and bedding before the intervention. Educational newsletters on children’s bedding control were sent to 21 CCCs by mail, and teachers were asked to distribute the newsletters to the parents of the children (intervention group. The remaining 17 CCCs were not sent newsletters (control group. The measurement of Der 1 concentrations in 38 CCCs was repeated after the intervention. Dust samples were collected with a vacuum cleaner and analyzed using enzyme-linked immunosorbent assay methods. Results The Der 1 concentrations on the bedding were significantly higher than those on the floors in 38 CCCs at baseline (p<0.05. Although changes of the Der 1 concentrations for the control group (n=17 were not significant, Der 1 concentrations for the intervention group (n=21 decreased significantly from 2077.9 ng/g dust to 963.5 ng/g dust on the floors and from 3683.9 ng/g dust to 610.4 ng/g dust on bedding (p<0.05. Conclusions The distribution of educational newsletters on bedding control to parents may be an effective means of controlling HDMs in CCCs.

Simulation of the mineral dust content over Western Africa from the event to the annual scale with the CHIMERE-DUST model

Directory of Open Access Journals (Sweden)

C. Schmechtig

2011-07-01

Full Text Available The chemistry and transport model CHIMERE-DUST have been used to simulate the mineral dust cycle over the Sahara in 2006. Surface measurements deployed during the AMMA field campaign allow to test the capability of the model to correctly reproduce the atmospheric dust load and surface concentrations from the daily to the seasonal time-scale. The simulated monthly mean Aerosol Optical Depths (AOD and surface concentrations are significantly correlated with the measured ones. The simulated daily concentrations and hourly AOD are in the same range of magnitude than the observed ones despite relatively high simulated dust emissions. The level of agreement between the simulations and the observations has been quantified at different time scales using statistical parameters classically used to evaluate air quality models. The capability of the model to reproduce the altitude of the dust transport was tested for two contrasted cases of low and high altitude transport. These results highlight the sensitivity of the simulations to the surface winds used as external forcing and the necessity to further constrain the dust mass budget at the regional scale.

African dust outbreaks over the Mediterranean Basin during 2001-2011: concentrations, phenomenology and trends

Science.gov (United States)

Pey, Jorge; Querol, Xavier; Alastuey, Andres; Forastiere, Franceso; Stafoggia, Massimo

2013-04-01

Concentrations, phenomenology and trends of African dust outbreaks over the whole Mediterranean Basin werestudied on an 11-year period (2001-2011). This work has been performed in the context of the MED-PARTICLES (LIFE programme, EU) project, devoted to quantify short-term health effects of particulate matter over the Mediterranean region by distinguishing different particle sizes, chemical components and sources, with emphasis in the effects of African dust. In order to evaluate conduct this investigation, PM10 data from 19 regional and suburban background sites West to East in the Mediterranean area were compiled. After identifying the daily occurrence of African dust outbreaks, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sitesacross the Mediterranean, from 30 to 37 % of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25°E westwards across the Basin,is patent across the Mediterranean. From 25°E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodesof dust but also because of inputs from Middle Eastern deserts. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 µg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn

Comparison of Respirable Mass Concentrations Measured by a Personal Dust Monitor and a Personal DataRAM to Gravimetric Measurements.

Science.gov (United States)

Halterman, Andrew; Sousan, Sinan; Peters, Thomas M

2017-12-15

In 2016, the Mine Safety and Health Administration required the use of continuous monitors to measure respirable dust in mines and better protect miner health. The Personal Dust Monitor, PDM3700, has met stringent performance criteria for this purpose. In a laboratory study, respirable mass concentrations measured with the PDM3700 and a photometer (personal DataRam, pDR-1500) were compared to those measured gravimetrically for five aerosols of varying refractive index and density (diesel exhaust fume, welding fume, coal dust, Arizona road dust (ARD), and salt [NaCl] aerosol) at target concentrations of 0.38, 0.75, and 1.5 mg m-3. For all aerosols except coal dust, strong, near-one-to-one, linear relationships were observed between mass concentrations measured with the PDM3700 and gravimetrically (diesel fume, slope = 0.99, R2 = 0.99; ARD, slope = 0.98, R2 = 0.99; and NaCl, slope = 0.95, R2 = 0.99). The slope deviated substantially from unity for coal dust (slope = 0.55; R2 = 0.99). Linear relationships were also observed between mass concentrations measured with the pDR-1500 and gravimetrically, but one-to-one behavior was not exhibited (diesel fume, slope = 0.23, R2 = 0.76; coal dust, slope = 0.54, R2 = 0.99; ARD, slope = 0.61, R2 = 0.99; NaCl, slope = 1.14, R2 = 0.98). Unlike the pDR-1500, mass concentrations measured with the PDM3700 appear independent of refractive index and density, suggesting that it could have applications in a variety of occupational settings. © The Author(s) 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Engineering gravimetric monitoring methods to cope with excessively high dust levels-2.

CSIR Research Space (South Africa)

Belle, BK

1999-11-01

Full Text Available -test and F-test), the mean dust concentration measured by pairs of cyclones is not significantly affected at 95 percent level of confidence. In other words, there is no difference between the measured mean dust concentration levels between various sampler... List of Figures . . . . . . . 8 List of Tables . . . .. . . 11 Glossary of Abbreviations and Symbols . . . . . 12 Acknowledgements . . . . . . . . 13 1 Introduction . . . . . . . 14 2 Background . . . . . . . 14 3 Test Samplers . . . . . . . 16...

[Asthma due to grain dust].

Science.gov (United States)

Baur, X; Preisser, A; Wegner, R

2003-06-01

The actual literature as well as two case reports described in detail show that grain dust induces asthmatic reactions and ODTS which are obviously not of allergic origin. For diagnosis occupational-type exposure tests are decisive whereas allergological testing usually is not. Endotoxins which are present in the grain dust samples in high concentrations have to be regarded as the major causative components. To avoid irreversible lung function impairment a comprehensive early diagnosis is necessary. Generally, a remarkable reduction of exposure to dust with high levels of airborne endotoxin in agriculture has to be achieved since in many workplaces corresponding exposures are still rather high.

Radioactive dust concentration around the Ranger uranium mine

International Nuclear Information System (INIS)

Kavasnicka, Jiri.

1988-07-01

Environmental dust sampling and wind direction/velocity monitory were carried out between July and November 1987 at five points around the Ranger Uranium Mines project near Jabiru, Northern Territory. The measured radioactive dust alpha activities in the air were used to calculate the radioactive dust source-term and develop a site-specific air dispersion model which takes the depletion of the dust plume into account. The above model was used to estimate the effective committed dose equivalent as 15 μSv/year to children in Jabiru East. This corresponds to an increase of 2.6 x 10 -4 Bq. m -3 in the annual average dust alpha activity above the natural background. The dose to the children in Jabiru is about 5 μSv/year, so that the critical group of the public is in Jabiru East. 12 refs., 11 tabs., 2 maps

A case of extreme particulate matter concentrations over Central Europe caused by dust emitted over the southern Ukraine

Directory of Open Access Journals (Sweden)

W. Birmili

2008-02-01

Full Text Available On 24 March 2007, an extraordinary dust plume was observed in the Central European troposphere. Satellite observations revealed its origins in a dust storm in Southern Ukraine, where large amounts of soil were resuspended from dried-out farmlands at wind gusts up to 30 m s⁻¹. Along the pathway of the plume, maximum particulate matter (PM₁₀ mass concentrations between 200 and 1400 μg m⁻³ occurred in Slovakia, the Czech Republic, Poland, and Germany. Over Germany, the dust plume was characterised by a volume extinction coefficient up to 400 Mm⁻¹ and a particle optical depth of 0.71 at wavelength 0.532 μm. In-situ size distribution measurements as well as the wavelength dependence of light extinction from lidar and Sun photometer measurements confirmed the presence of a coarse particle mode with diameters around 2–3 μm. Chemical particle analyses suggested a fraction of 75% crustal material in daily average PM₁₀ and up to 85% in the coarser fraction PM_10–2.5. Based on the particle characteristics as well as a lack of increased CO and CO₂ levels, a significant impact of biomass burning was ruled out. The reasons for the high particle concentrations in the dust plume were twofold: First, dust was transported very rapidly into Central Europe in a boundary layer jet under dry conditions. Second, the dust plume was confined to a relatively stable boundary layer of 1.4–1.8 km height, and could therefore neither expand nor dilute efficiently. Our findings illustrate the capacity of combined in situ and remote sensing measurements to characterise large-scale dust plumes with a variety of aerosol parameters. Although such plumes from Southern Eurasia seem to occur rather infrequently in Central Europe, its unexpected features highlights the need to improve the description of dust emission, transport and transformation processes needs, particularly when facing the

Characterization of wood dust emission from hand-held woodworking machines.

Science.gov (United States)

Keller, F-X; Chata, F

2018-01-01

This article focuses on the prevention of exposure to wood dust when operating electrical hand-held sawing and sanding machines. A laboratory methodology was developed to measure the dust concentration around machines during operating processes. The main objective was to characterize circular saws and sanders, with the aim of classifying the different power tools tested in terms of dust emission (high dust emitter vs. low dust emitter). A test set-up was developed and is described and a measurement methodology was determined for each of the two operations studied. The robustness of the experimental results is discussed and shows good tendencies. The impact of air-flow extraction rate was assessed and the pressure loss of the system for each machine established. For the circular saws, three machines over the nine tested could be classified in the low dust emitter group. Their mean concentration values measured are between 0.64 and 0.98 mg/m 3 for the low dust emitter group and from 2.55 and 4.37 mg/m 3 for the high dust emitter group. From concentration measurements, a machine classification is possible-one for sanding machines and one for sawing machines-and a ratio from 1-7 is obtained when comparing the results. This classification will be helpful when a choice of high performance power tools, in terms of dust emission, must be made by professionals.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-01-15

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

Concentrations of legacy and novel brominated flame retardants in indoor dust in Melbourne, Australia: An assessment of human exposure.

Science.gov (United States)

McGrath, Thomas J; Morrison, Paul D; Ball, Andrew S; Clarke, Bradley O

2018-04-01

Polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFR) have been used in a range of polymers to inhibit the spread of fires but also have a propensity to migrate out of consumer materials and contaminate indoor dust. In this study, a total of 57 dust samples were collected from 12 homes, eight offices and eight vehicles in Melbourne, Australia and analysed for eight PBDEs (-28, -47, -99, -100, -153, -154, -183 and -209) and seven NBFRs (PBT, PBEB, HBB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) to determine human exposure risks from dust ingestion. Samples were analysed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Legacy and replacement flame retardants were detected in all samples with overall ∑PBDE concentrations ranging from 120 to 1700,000 ng/g (median 2100 ng/g) and ∑NBFRs ranging from 1.1 to 10,000 ng/g (median 1800 ng/g). BDE-209 and DBDPE were the dominant compounds in dust samples, followed by congeners associated with commercial Penta-BDE formulations (-47, -99, -100, -153 and -154) and then EH-TBB of the FireMaster 550 and BZ-54 products. ∑Penta-BDE concentrations were elevated in office samples compared with homes and vehicles, while EH-TBB and BDE-209 measured higher concentrations in vehicles compared with their respective levels in homes and offices. Risk assessment estimates revealed the majority of exposure to occur in the home for both adults and toddlers in the City of Melbourne. Generally, body weight adjusted exposure to PBDEs and NBFRs was predicted to be 1 to 2 orders of magnitude higher for toddlers than adults. Estimated rates of BDE-47, -99, -153 and -209 ingestion were each 2 orders of magnitude or more below the USEPA's prescribed oral reference dose values (RfDs) for typical exposure scenarios. However, exposure rates for BDE-47 and -99 reached as high as 52 and 95% of RfDs, respectively, for adults and 4.4 and 7

Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure.

Science.gov (United States)

Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S Katharine

2015-03-01

This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57-410) in gasoline buses and 3.97 ± 1.81 (range: 2.01-9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies on radioactivities of dust samples in the air at high altitudes

International Nuclear Information System (INIS)

Kohara, Eri; Muronoi, Naohiro

2015-01-01

The radioactivity concentrations of airborne dust samples were studied. The samples had been collected at high altitude by the Japan Air Self-Defense Force from April 2013 to March 2014. The obtained data were used for gross beta radioactivity analysis and gamma nuclide analysis. It is shown that cesium 137 was mainly detected at the 10 km and 3 km altitude of central area of Japan in several samples. Gaseous radioiodine was not detected in all the samples. Radioactive xenon was detected but the concentration did not show significant difference to the background level. (author)

A supernova origin for dust in a high-redshift quasar.

Science.gov (United States)

Maiolino, R; Schneider, R; Oliva, E; Bianchi, S; Ferrara, A; Mannucci, F; Pedani, M; Sogorb, M Roca

2004-09-30

Interstellar dust plays a crucial role in the evolution of the Universe by assisting the formation of molecules, by triggering the formation of the first low-mass stars, and by absorbing stellar ultraviolet-optical light and subsequently re-emitting it at infrared/millimetre wavelengths. Dust is thought to be produced predominantly in the envelopes of evolved (age >1 Gyr), low-mass stars. This picture has, however, recently been brought into question by the discovery of large masses of dust in the host galaxies of quasars at redshift z > 6, when the age of the Universe was less than 1 Gyr. Theoretical studies, corroborated by observations of nearby supernova remnants, have suggested that supernovae provide a fast and efficient dust formation environment in the early Universe. Here we report infrared observations of a quasar at redshift 6.2, which are used to obtain directly its dust extinction curve. We then show that such a curve is in excellent agreement with supernova dust models. This result demonstrates a supernova origin for dust in this high-redshift quasar, from which we infer that most of the dust at high redshifts probably has the same origin.

Dust exposure and pneumoconiosis in a South African pottery. 1. Study objectives and dust exposure.

Science.gov (United States)

Rees, D; Cronje, R; du Toit, R S

1992-07-01

Dust exposure and pneumoconiosis were investigated in a South African pottery that manufactured wall tiles and bathroom fittings. This paper describes the objectives of the investigation and presents dust measurement data. x Ray diffraction showed that the clays used by the pottery had a high quartz content (range 58%-23%, mean 38%). Exposure to respirable dust was measured for 43 workers and was highest (6.6 mg/m3) in a bathroom fitting fettler. Quartz concentrations in excess of 0.1 mg/m3 were found in all sections of the manufacturing process from slip production to biscuit firing and sorting. The proportion of quartz in the respirable dust of these sections was 24% to 33%. This is higher than is usually reported in English potteries. Four hundred and six (80%) of the 509 workers employed at the pottery were potentially at risk of occupational lung disease. The finding of large numbers of pottery workers exposed to unacceptable dust concentrations is not surprising as poor dust control was found in all six wall tile and sanitary ware factories surveyed by the National Centre for Occupational Health between 1973 and 1989. Dust related occupational disease can be expected in potters for many years to come.

Development of High-Resolution Dynamic Dust Source Function - A Case Study with a Strong Dust Storm in a Regional Model

Science.gov (United States)

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

2017-01-01

A high-resolution dynamic dust source has been developed in the NASA Unified-Weather Research and Forecasting (NU-WRF) model to improve the existing coarse static dust source. In the new dust source map, topographic depression is in 1-km resolution and surface bareness is derived using the Normalized Difference Vegetation Index (NDVI) data from Moderate Resolution Imaging Spectroradiometer (MODIS). The new dust source better resolves the complex topographic distribution over the Western United States where its magnitude is higher than the existing, coarser resolution static source. A case study is conducted with an extreme dust storm that occurred in Phoenix, Arizona in 0203 UTC July 6, 2011. The NU-WRF model with the new high-resolution dynamic dust source is able to successfully capture the dust storm, which was not achieved with the old source identification. However the case study also reveals several challenges in reproducing the time evolution of the short-lived, extreme dust storm events.

Development of High-Resolution Dynamic Dust Source Function -A Case Study with a Strong Dust Storm in a Regional Model.

Science.gov (United States)

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

2017-06-01

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

Double Compressions of Atmospheric Depth by Geopotential Tendency, Vorticity, and Atmospheric Boundary Layer Affected Abrupt High Particulate Matter Concentrations at a Coastal City for a Yellow Dust Period in October

Directory of Open Access Journals (Sweden)

Hyo Choi

2014-01-01

Full Text Available Using GRIMM-aerosol sampler, NOAA-HYSPLIT model, and 3D-WRF-3.3 model, the transportation of dusts from Gobi Desert toward Gangneung city, Korea was investigated from 09:00 LST October 27 to 04:00 LST October 28, 2003. Maximum PM10 (PM2.5, PM1 concentration was detected with 3.8 (3.4, 14.1 times higher magnitude than one in non-Yellow Dust period. The combination of dusts transported from the desert under westerly wind with particulate matters and gases from vehicles on the road of the city caused high PM concentrations near the ground surface at 09:00 LST and their maxima at 17:00 LST near sunset with further pollutants from heating boilers in the resident area. Positive geopotential tendency at the 500 hPa level of the city (∂Φ/∂t; m day−1 corresponding to negative vorticity of -4×10-5 sec−1 (-2.5×10-5 sec−1 at 0900 LST (21:00 LST; at night was +83 m day−1 (+30 m day−1 and it caused atmospheric depth between 500 hPa level and the ground surface to be vertically expanded. However, its net reduction to −53 m/12 hrs until 21:00 LST indicated synoptic-scale atmospheric layer to be vertical shrunken, resulting in the increase of PM concentrations at 17:00 LST. Simultaneously, much shallower microscale stable nocturnal surface inversion layer (NSIL than daytime thermal internal boundary layer induced particulate matters to be merged inside the NSIL, resulting in maximum PM concentrations at 17:00 LST.

Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece

International Nuclear Information System (INIS)

Besis, Athanasios; Katsoyiannis, Athanasios; Botsaropoulou, Elisavet; Samara, Constantini

2014-01-01

Polybrominated Diphenyl Ethers (PBDEs) are ubiquitous in the indoor environment owing to their use in consumer products and various studies around the world have found higher concentrations indoors than outdoors. Central air conditioner (A/C) systems have been widely used in many workplaces, therefore, studying of PBDEs in central A/C filter dust is useful to better understand the occurrences and health implications of PBDEs in indoor environments. The present study examined the occurrence of PBDEs in central A/C filter dust collected from various workplaces (n = 20) in Thessaloniki, Greece. The sum concentrations of 21 target congeners (∑ 21 PBDE) in A/C dust ranged between 84 and 4062 ng g −1 with a median value of 1092 ng g −1 , while BDE-209 was found to be the most abundant BDE congener. The daily intake via dust ingestion of PBDEs estimated for the employees of the occupational settings ranged from 3 to 45 ng day −1 (median 12 ng day −1 ). - Highlights: • PBDEs were investigated in dust of A/C filters in occupational settings in Thessaloniki, Greece. • BDE-209 was found to be the most abundant BDE congener. • High levels of PBDEs were found in a newspaper building, internet cafes and electronic shops. • PBDEs were attributable to the extensive presence and/or usage of electronic devices. • Exposure of employees to PBDEs via indoor dust ingestion was estimated at 12 ng day −1 . - PBDEs were for the first time measured in dust from central A/C filters in workplaces of Greece and their concentrations were used to estimate the non-dietary human exposure

Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure

International Nuclear Information System (INIS)

Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S. Katharine

2015-01-01

This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57–410) in gasoline buses and 3.97 ± 1.81 (range: 2.01–9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. - Highlights: • Resuspendable fraction of settled dust from microenvironment of buses in Harbin monitored for PAHs exposure assessment. • Higher levels of PAHs pollutants at gasoline-powered buses than at compressed natural gas-powered buses. • Non-occupational and occupational exposures in the microenvironment of buses are assessed. - Occupational and non-occupational exposure to PAHs from the microenvironment of bus

Pantoea agglomerans: a mysterious bacterium of evil and good. Part II--Deleterious effects: Dust-borne endotoxins and allergens--focus on grain dust, other agricultural dusts and wood dust.

Science.gov (United States)

Dutkiewicz, Jacek; Mackiewicz, Barbara; Lemieszek, Marta Kinga; Golec, Marcin; Skórska, Czesława; Góra-Florek, Anna; Milanowski, Janusz

2016-01-01

Pantoea agglomerans, a Gram-negative bacterium developing in a variety of plants as epiphyte or endophyte is particularly common in grain and grain dust, and has been identified by an interdisciplinary group from Lublin, eastern Poland, as a causative agent of work-related diseases associated with exposure to grain dust and other agricultural dusts. The concentration of P. agglomerans in grain as well as in the settled grain and flour dust was found to be high, ranging from 10(4)-10(8) CFU/g, while in the air polluted with grain or flour dust it ranged from 10(3)-10(5) CFU/m(3) and formed 73.2-96% of the total airborne Gram-negative bacteria. The concentration of P. agglomerans was also relatively high in the air of the facilities processing herbs and other plant materials, while it was lower in animal farms and in wood processing facilities. Pantoea agglomerans produces a biologically-potent endotoxin (cell wall lipopolysaccharide, LPS). The significant part of this endotoxin occurs in dusts in the form of virus-sized globular nanoparticles measuring 10-50 nm that could be described as the 'endotoxin super-macromolecules'. A highly significant relationship was found (R=0.804, P=0.000927) between the concentration of the viable P. agglomerans in the air of various agricultural and wood industry settings and the concentration of bacterial endotoxin in the air, as assessed by the Limulus test. Although this result may be interfered by the presence of endotoxin produced by other Gram-negative species, it unequivocally suggests the primary role of the P. agglomerans endotoxin as an adverse agent in the agricultural working environment, causing toxic pneumonitis (ODTS). Numerous experiments by the inhalation exposure of animals to various extracts of P. agglomerans strains isolated from grain dust, including endotoxin isolated with trichloroacetic acid (LPS-TCA), endotoxin nanoparticles isolated in sucrose gradient (VECN), and mixture of proteins and endotoxin obtained

Cow allergen (Bos d2) and endotoxin concentrations are higher in the settled dust of homes proximate to industrial-scale dairy operations.

Science.gov (United States)

Williams, D' Ann L; McCormack, Meredith C; Matsui, Elizabeth C; Diette, Gregory B; McKenzie, Shawn E; Geyh, Alison S; Breysse, Patrick N

2016-01-01

Airborne contaminants produced by industrial agricultural facilities contain chemical and biological compounds that can impact the health of residents living in close proximity. Settled dust can be a reservoir for these contaminants and can influence long-term exposures. In this study, we sampled the indoor- and outdoor-settled dust from 40 homes that varied in proximity to industrial-scale dairies (ISD; industrial-scale dairy, a term used in this paper to describe a large dairy farm and adjacent waste sprayfields, concentrated animal feeding operation or animal feeding operation, that uses industrial processes) in the Yakima Valley, Washington. We analyzed settled dust samples for cow allergen (Bos d2, a cow allergen associated with dander, hair, sweat and urine, it is a member of the lipocalin family of allergens associated with mammals), mouse allergen (Mus m1; major mouse allergen, a mouse urinary allergen, in the lipocalin family), dust mite allergens (Der p1 (Dermatophagoides pteronissinus 1) and Der f1 (Dermatophagoides farinae 1)), and endotoxin (a component of the cell walls of gram negative bacteria, lipopolysaccharide, which can be found in air and dust and can produce a strong inflammatory response). A concentration gradient was observed for Bos d2 and endotoxin measured in outdoor-settled dust samples based on proximity to ISD. Indoor-settled dust concentrations of Bos d2 and endotoxin were also highest in proximal homes. While the associated health effects of exposure to cow allergen in settled dust is unknown, endotoxin at concentrations observed in these proximal homes (100 EU/mg) has been associated with increased negative respiratory health effects. These findings document that biological contaminants emitted from ISDs are elevated in indoor- and outdoor-settled dust samples at homes close to these facilities and extend to as much as three miles (4.8 km) away.

Dust mobilization by high-speed vapor flow under LOVA

International Nuclear Information System (INIS)

Matsuki, K.; Suzuki, S.; Ebara, S.; Yokomine, T.; Shimizu, A.

2006-01-01

In the safety analysis on the International Thermonuclear Experimental Reactor (ITER), the ingress of coolant (ICE) event and the loss of vacuum (LOVA) event are considered as one of the most serious accident. On the assumption of LOVA occurring after ICE, it is inferable that activated dusts are under the wet condition. Transport behavior of in-vessel activated dusts under the wet condition is not well understood in comparison with the dry case. In this study, we experimentally investigated the entrainment behavior of dust under LOVA after ICE. We measured dust entrainment by high-speed humid airflow with phase change. Graphite dusts and glass beads are used as substitutions for mobile inventory. The relations among the relative humidity, the entrainment of particles in the exhaust gas flow and the adhesion rate of dust particles on the pipe wall have been made clear, as has the distribution profile of dust deposition on the pipe wall. The entrainment ratio decreased as the relative humidity increased and increased as the initial pressure difference increased

Pantoea agglomerans : a mysterious bacterium of evil and good. Part II. Deleterious effects: Dust-borne endotoxins and allergens – focus on grain dust, other agricultural dusts and wood dust

Directory of Open Access Journals (Sweden)

Jacek Dutkiewicz

2015-12-01

Full Text Available Pantoea agglomerans , a Gram-negative bacterium developing in a variety of plants as epiphyte or endophyte is particularly common in grain and grain dust, and has been identified by an interdisciplinary group from Lublin, eastern Poland, as a causative agent of work-related diseases associated with exposure to grain dust and other agricultural dusts. The concentration of [i]P. agglomerans[/i] in grain as well as in the settled grain and flour dust was found to be high, ranging from 10 4 –10 8 CFU/g, while in the air polluted with grain or flour dust it ranged from 10 3 –10 5 CFU/m 3 and formed 73.2–96% of the total airborne Gram-negative bacteria. The concentration of P. agglomerans was also relatively high in the air of the facilities processing herbs and other plant materials, while it was lower in animal farms and in wood processing facilities. Pantoea agglomerans produces a biologically-potent endotoxin (cell wall lipopolysaccharide, LPS. The significant part of this endotoxin occurs in dusts in the form of virus-sized globular nanoparticles measuring 10–50 nm that could be described as the ‘endotoxin super-macromolecules’. A highly significant relationship was found (R=0.804, P=0.000927 between the concentration of the viable P. agglomerans in the air of various agricultural and wood industry settings and the concentration of bacterial endotoxin in the air, as assessed by the Limulus test. Although this result may be interfered by the presence of endotoxin produced by other Gram-negative species, it unequivocally suggests the primary role of the P. agglomerans endotoxin as an adverse agent in the agricultural working environment, causing toxic pneumonitis (ODTS. Numerous experiments by the inhalation exposure of animals to various extracts of P. agglomerans strains isolated from grain dust, including endotoxin isolated with trichloroacetic acid (LPS-TCA, endotoxin nanoparticles isolated in sucrose gradient (VECN, and mixture of

Organophosphate esters and phthalate esters in human hair from rural and urban areas, Chongqing, China: Concentrations, composition profiles and sources in comparison to street dust.

Science.gov (United States)

He, Ming-Jing; Lu, Jun-Feng; Ma, Jing-Ye; Wang, Huan; Du, Xiao-Fan

2018-06-01

Human hair and street dust from rural and urban areas in Chongqing were collected to analyze Organophosphate esters (OPEs) and phthalate esters (PAEs). Concentrations of OPEs in urban hair were significantly higher than those in rural hair, whereas PAEs concentrations in rural hair were significantly higher than those in urban hair. Different composition patterns of OPEs were observed in rural and urban hair, where tris (2-chloroisopropyl) phosphate (TCIPP), tris (butyl) phosphate (TNBP) and triphenyl phosphate (TPHP) were the dominating analogues in rural hair, accounting for 62.1% of the OPEs burden, and tris (methylphenyl) phosphate (TMPP) exhibited a high contribution in urban hair, responsible for 51.3% of total OPEs, which differed from the composition profiles in corresponding street dust. Analogous composition patterns of PAEs were found in hair of both areas. Di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DNBP), diisobutyl phthalate (DIBP) and diethyl phthalate (DEP) were the most abundant analogues in hair samples, while DEHP was the predominant analogue in dust samples. No clear tendency was obtained between the increasing ages and the concentrations of both compounds. Most OPEs and PAEs congeners showed significantly positive correlation with one another in rural hair. On the contrary, different correlation patterns were observed in urban hair for OPEs and PAEs, indicating multiple or additional sources existed in urban areas. Significant correlations of OPEs and PAEs were found between hair and corresponding street dust samples, but poor correlations of OPEs and PAEs were observed between rural hair and rural indoor dust, suggesting that street dust may be a predominant exogenous source for human exposure to OPEs and PAEs in this area. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biodegradation studies of oil sludge containing high hydrocarbons concentration

International Nuclear Information System (INIS)

Olguin-Lora, P.; Munoz-Colunga, A.; Castorena-Cortes, G.; Roldan-Carrillo, T.; Quej Ake, L.; Reyes-Avila, J.; Zapata-Penasco, I.; Marin-Cruz, J.

2009-01-01

Oil industry has a significant impact on environment due to the emission of, dust, gases, waste water and solids generated during oil production all the way to basic petrochemical product manufacturing stages. the aim of this work was to evaluate the biodegradation of sludge containing high hydrocarbon concentration originated by a petroleum facility. A sludge sampling was done at the oil residuals pool (ORP) on a gas processing center. (Author)

Correlation between Yellow Dust and Radioactivity

International Nuclear Information System (INIS)

AIZaabia, Mouza A; Kim, Byoung-Jik

2015-01-01

In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, 137 Cs and 7 Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides

Iron content and solubility in dust from high-alpine snow along a north-south transect of High Asia

OpenAIRE

Wu, Guangjian; Zhang, Chenglong; Li, Zhongqin; Zhang, Xuelei; Gao, Shaopeng

2012-01-01

This study describes the dissolved and insoluble iron fraction of dust (mineral aerosol) in high-alpine snow samples collected along a north-south transect across High Asia (Eastern Tien Shan, Qilian Shan, and Southern Tibetan Plateau). This dust provides the basic chemical properties of mid- and high-level tropospheric Asian dust that can supply the limiting iron nutrient for phytoplankton growth in the North Pacific. The iron content in Asian dust averages 4.95% in Eastern Tien Shan, 3.38–5...

Applications of high-speed dust injection to magnetic fusion

International Nuclear Information System (INIS)

Wang, Zhehui; Li, Yangfang

2012-01-01

It is now an established fact that a significant amount of dust is produced in magnetic fusion devices due to plasma-wall interactions. Dust inventory must be controlled, in particular for the next-generation steady-state fusion machines like ITER, as it can pose significant safety hazards and degrade performance. Safety concerns are due to tritium retention, dust radioactivity, toxicity, and flammability. Performance concerns include high-Z impurities carried by dust to the fusion core that can reduce plasma temperature and may even induce sudden termination of the plasma. We have recognized that dust transport, dust-plasma interactions in magnetic fusion devices can be effectively studied experimentally by injection of dust with known properties into fusion plasmas. Other applications of injected dust include diagnosis of fusion plasmas and edge localized mode (ELM)'s pacing. In diagnostic applications, dust can be regarded as a source of transient neutrals before complete ionization. ELM's pacing is a promising scheme to prevent disruptions and type I ELM's that can cause catastrophic damage to fusion machines. Different implementation schemes are available depending on applications of dust injection. One of the simplest dust injection schemes is through gravitational acceleration of dust in vacuum. Experiments at Los Alamos and Princeton will be described, both of which use piezoelectric shakers to deliver dust to plasma. In Princeton experiments, spherical particles (40 micron) have been dropped in a systematic and reproducible manner using a computer-controlled piezoelectric bending actuator operating at an acoustic (0,2) resonance. The circular actuator was constructed with a 2.5 mm diameter central hole. At resonance (∼ 2 kHz) an applied sinusoidal voltage has been used to control the flux of particles exiting the hole. A simple screw throttle located ∼1mm above the hole has been used to set the magnitude of the flux achieved for a given voltage

Exposure to dust and its particle size distribution in shoe manufacture and repair workplaces measured with GRIMM laser dust monitor.

Science.gov (United States)

Stroszejn-Mrowca, Grazyna; Szadkowska-Stańczyk, Irena

2003-01-01

Owing to a diversified technological process and a great variety of products and materials used in shoe manufacture, workers may be exposed to dusts that contain different chemicals and particles of various shapes and sizes. The aim of this study was to assess the dust exposure, taking account of concentration of particular size fractions according to the European Standard Norm, and to analyze particle size distribution in inhalable dust at selected workplaces in a modern shoe manufacture plant and in a small shoe repair workshop in comparison with other industrial branches. In these two workplaces, the concentrations of dust, representing the inhalable, thoracic, and respirable fractions, were measured with the GRIMM 1.105 laser dust monitor. The particle size distribution in inhaled dust in the most characteristic workposts was analyzed. In the shoe manufacture plant, the concentrations ranged from 124 microg/m3 (leather cutting out) to 724 microg/m3 (scouring and milling of soles); concentrations of the thoracic and respirable fractions in the same workposts ranged from 74 microg/m3 to 412 microg/m3 and from 24 microg/m3 to 120 microg/m3, respectively. In the shoe repair workshop, the recorded concentrations were higher: the values ranged from 521 microg/m3 (gluing of shoes and soles, zipper exchange and heel abrasion) to 916 microg/m3 (uppers sewing and heel scouring) for the inhaled fraction; from 335 microg/m3 to 499 microg/m3 for the thoracic fraction; and from 88 microg/m3 to 120 microg/m3 for the respirable fraction. The mass median aerodynamic diameters of inhalable dust particles fell within the limits of 6.2-25.0 mm. Dust with the smallest particles (MMAD = 6.2 mm) was observed in shoe brushing and polishing, and with the largest particles (MMAD = 25.0 mm) in uppers sewing. The modern process of shoe manufacture is characterized by very low concentrations of inhalable dust and its fractions, they are considerably lower than occupational exposure limits

MEASUREMENTS OF DUST EXTINCTION IN HIGHLY INCLINED SPIRAL GALAXIES

NARCIS (Netherlands)

JANSEN, RA; KNAPEN, JH; BECKMAN, JE; PELETIER, RF; HES, R

1994-01-01

We study the extinction properties of dust in the well-defined dust lanes of four highly inclined galaxies, using U-, B-, V-, R- and I-band CCD and J- and K'-band near-infrared array images. For three of these galaxies, we could use the symmetry of the underlying light profile to obtain absolute

Dust Formation, Evolution, and Obscuration Effects in the Very High-Redshift Universe

Science.gov (United States)

Dwek, Eli; Staguhn, Johannes; Arendt, Richard G.; Kovacs, Attila; Su, Ting; Benford, Dominic J.

2014-01-01

The evolution of dust at redshifts z > or approx. 9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production comported to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This "silicate-UV break" may be confused with the Lyman break, resulting in a misidentification of a galaxies' photometric redshift. In this paper we demonstrate these effects by analyzing the spectral energy distribution (SED) of MACS1149-JD, a lensed galaxy at z = 9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high redshift universe. Subject headings: galaxies: high-redshift - galaxies: evolution - galaxies: individual (MACS1149- JD) - Interstellar medium (ISM), nebulae: dust, extinction - physical data and processes: nuclear reactions, nucleosynthesis, abundances.

Exposure to dust mixtures containing free crystalline silica and mineral fibers

International Nuclear Information System (INIS)

Wozniak, H.; Wiecek, E.; Bielichowska-Cybula, G.

1996-01-01

Exposure to dust mixture containing at the same time respirable mineral fibres and free crystalline silica may occur in Poland in mines and in the Lower Silesia plants processing mineral raw materials as well as in all plants which use asbestos products and MMMF. Workposts where thermal insulation is exchange with possible phase transformations during operations under conditions of high temperature, expose particularly complex problems. In the work environment of this kind, dust concentration of free crystalline silica becomes important but not sufficient criterion for evaluating working conditions and it may be misleading. A range of studies indispensable for the proper evaluation of exposure to dust, covering together with measurement of dust and SiO 2 concentrations, determination of the mineral composition of dust, was developed. It was also found that the acceptable level of risk for neoplastic disease, namely 10(-3) can be attained in the work environment only if the concentration ranges from 0.05 to 0.1 f/cm 3 , that is equal to 20% of MAC value which is now binding in Poland. Cancer risk (lung cancer and mesothelioma jointly) during a 20-year exposure to concentrations equal to present MAC values should be estimated as about 10(-2) what indicates that risk is too high and it is necessary to diminish MAC values for asbestos dust. (author). 17 refs, 3 tabs

Ventilation in homes infested by house-dust mites.

Science.gov (United States)

Sundell, J; Wickman, M; Pershagen, G; Nordvall, S L

1995-02-01

Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.

CHARACTERIZATION OF THE DUST GENERATED IN THE RECYCLING PROCESS OF THE ELECTRIC ARC FURNACE DUST

Directory of Open Access Journals (Sweden)

Fábio Gonçalves Rizz

2013-10-01

Full Text Available Electric Arc Furnace Dust (EAFD is a solid waste generated by the production of steel through the Electric Arc Furnace. This waste is labeled dangerous, which motivates studies aiming its recycling. Experiments were made to study a pyrometallurgical process for the recycling of the dust, using the insertion of dust briquettes in molten pig iron in three temperatures. In the briquettes, there were made additions of calcium fluoride in four different concentrations. This paper has the objective to characterize the dust that results from this process, verifying the influence of the temperature and the concentration of calcium fluoride in the briquette in the morphology and chemical composition of the new dust, determining the optimal conditions for the recovery of the zinc content of the dust. This newly generated dust was analyzed in an Scanning Electronic Microscope, used to capture micrographs and chemical composition by EDS. The micrographs show that the temperature and the calcium fluoride concentration interfere in the way the dust particles agglomerate. Chemical analysis points that the higher zinc recuperation occurrs in the experiments at 1500°C with 7% addition of calcium fluoride.

Human exposure to brominated flame retardants through dust in different indoor environments: Identifying the sources of concentration differences in hair from men and women.

Science.gov (United States)

Li, Junqi; Dong, Zheng; Wang, Ying; Bao, Junsong; Yan, Yijun; Liu, Anming; Jin, Jun

2018-08-01

Brominated flame retardants (BFRs) can accumulate in humans and are associated with adverse health effects. The study was conducted to determine the differences in Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardant (Alt-BFR) concentrations between men and women. We analyzed hair samples from 14 male and 20 female university students, paired dust samples from their dormitories (10 for males and 8 for females), and six dust samples from university teaching buildings. The total PBDE concentrations in hair from females were significantly (three times) higher (p = 0.012) than that from males (means 372 and 109 ng/g, respectively). The mean total PBDE concentrations in classroom and dormitory dust were 36100 and 2012 ng/g, respectively. The PBDE patterns were different in the male and female hair samples, as were the patterns in the classroom and dormitory dust. There are no reports concerning human exposure to BFRs through dust that was assessed considering academic and residential environments simultaneously. The differences between BFR exposure for males and females and the differences between BFR concentrations in hair samples from males and females were consistent for 71.4% of the compounds. However, using only dormitory dust in the calculations gave consistent differences only for 28.6% of the compounds, suggesting that the BFR concentration differences in hair were mainly because females spent much more time than males in classrooms. Copyright © 2018 Elsevier Ltd. All rights reserved.

Correlation between Yellow Dust and Radioactivity

Energy Technology Data Exchange (ETDEWEB)

AIZaabia, Mouza A [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Byoung-Jik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2015-10-15

In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, {sup 137}Cs and {sup 7}Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides.

Paleo-dust insights onto dust-climate interactions

Science.gov (United States)

Albani, S.; Mahowald, N. M.

2017-12-01

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

High sensitivity of Indian summer monsoon to Middle East dust absorptive properties.

Science.gov (United States)

Jin, Qinjian; Yang, Zong-Liang; Wei, Jiangfeng

2016-07-28

The absorptive properties of dust aerosols largely determine the magnitude of their radiative impacts on the climate system. Currently, climate models use globally constant values of dust imaginary refractive index (IRI), a parameter describing the dust absorption efficiency of solar radiation, although it is highly variable. Here we show with model experiments that the dust-induced Indian summer monsoon (ISM) rainfall differences (with dust minus without dust) change from -9% to 23% of long-term climatology as the dust IRI is changed from zero to the highest values used in the current literature. A comparison of the model results with surface observations, satellite retrievals, and reanalysis data sets indicates that the dust IRI values used in most current climate models are too low, tending to significantly underestimate dust radiative impacts on the ISM system. This study highlights the necessity for developing a parameterization of dust IRI for climate studies.

Measurement of nicotine in household dust

International Nuclear Information System (INIS)

Kim, Sungroul; Aung, Ther; Berkeley, Emily; Diette, Gregory B.; Breysse, Patrick N.

2008-01-01

An analytical method of measuring nicotine in house dust was optimized and associations among three secondhand smoking exposure markers were evaluated, i.e., nicotine concentrations of both house dust and indoor air, and the self-reported number of cigarettes smoked daily in a household. We obtained seven house dust samples from self-reported nonsmoking homes and 30 samples from smoking homes along with the information on indoor air nicotine concentrations and the number of cigarettes smoked daily from an asthma cohort study conducted by the Johns Hopkins Center for Childhood Asthma in the Urban Environment. House dust nicotine was analyzed by isotope dilution gas chromatography-mass spectrometry (GC/MS). Using our optimized method, the median concentration of nicotine in the dust of self-reported nonsmoking homes was 11.7 ng/mg while that of smoking homes was 43.4 ng/mg. We found a substantially positive association (r=0.67, P<0.0001) between house dust nicotine concentrations and the numbers of cigarettes smoked daily. Optimized analytical methods showed a feasibility to detect nicotine in house dust. Our results indicated that the measurement of nicotine in house dust can be used potentially as a marker of longer term SHS exposure

Iron content and solubility in dust from high-alpine snow along a north-south transect of High Asia

Directory of Open Access Journals (Sweden)

Guangjian Wu

2012-04-01

Full Text Available This study describes the dissolved and insoluble iron fraction of dust (mineral aerosol in high-alpine snow samples collected along a north-south transect across High Asia (Eastern Tien Shan, Qilian Shan, and Southern Tibetan Plateau. This dust provides the basic chemical properties of mid- and high-level tropospheric Asian dust that can supply the limiting iron nutrient for phytoplankton growth in the North Pacific. The iron content in Asian dust averages 4.95% in Eastern Tien Shan, 3.38–5.41% along Qilian Shan and 3.85% in the Southern Tibetan Plateau. The iron fractional solubility averages about 0.25% in Eastern Tien Shan, 0.05–2% along Qilian Shan and 1.5% in the Southern Tibetan Plateau. Among the controlling factors that can affect iron solubility in Asian dust, such as dust composition and particle grain size, acidity seems to be the most significant and can increase the iron solubility by one or two orders of magnitude with acidification of pH=0.66. Our results reveal that iron solubility of dust in the remote downwind sites is higher than that in high-alpine snow, confirming the strong pH-dependence of iron solubility, and indicating that Asian dust shows a large variation in iron solubility on a regional scale.

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

Science.gov (United States)

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

2017-09-30

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-11-01

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

The Relationship between Aerosol Composition and Concentration and Visual Range on Barbados, West Indies: The Impact of African Dust

Science.gov (United States)

Huang, J.; Prospero, J.; Zhang, C.; Arimoto, R.

2006-12-01

Visual Range (VR) measured at Grantley Adams Airport on Barbados shows a very strong annual cycle with the minimum VR values occurring in June or July. This cycle closely matches the annual cycle of African dust concentrations measured in the trade winds at Barbados (13°15'N, 59°30'W) where observations first began in 1965. In winter, monthly mean VR was typically around 30 km or greater while in summer it frequently dipped below 20 km. This same clear signal is observed in the VR records from near-by islands where the same seasonal cycle of dust would be expected: St. Lucia, Martinique and Trinidad and Tobago. We examined the relationship between VR on Barbados and the concentrations of the three major aerosol constituents that we would expect to have the strongest influence on VR: mineral dust, sea salt, and non-sea- salt sulfate (nss-SO4^{=}). We used VR data for the period from 1973, when measurements first began, up to 2006. We found a large discrepancy between the observed VR at the airport and the VR derived from the Koschmieder equation using literature values for the optical properties of the aerosol components; this simple approach would require a much smaller constant than the commonly-used value, 3.912. We further explored the effects of particle size distribution and relative humidity. During boreal summer when VR is lowest, dust is the dominant supramicron aerosol component and it clearly is the major factor in controlling VR. Nonetheless the submicron fraction also has a comparable impact due to its significantly higher light scattering efficiency. During winter, when there is little or no dust, sea salt aerosol and sulfate are dominant. In this report we focus on the various factors that affect visibility on Barbados especially the role of aerosols dominated by supramicrometer particles. We also consider the effects of other factors such as wind speed and precipitation. Finally, we note that the close relationship between summertime VR and dust

Identification of mineral dust layers in high alpine snow packs

Science.gov (United States)

Greilinger, Marion; Kau, Daniela; Schauer, Gerhard; Kasper-Giebl, Anne

2017-04-01

Deserts serve as a major source for aerosols in the atmosphere with mineral dust as a main contributor to primary aerosol mass. Especially the Sahara, the largest desert in the world, contributes roughly half of the primarily emitted aerosol mass found in the atmosphere [1]. The eroded Saharan dust is episodically transported over thousands of kilometers with synoptic wind patterns towards Europe [2] and reaches Austria about 20 to 30 days per year. Once the Saharan dust is removed from the atmosphere via dry or wet deposition processes, the chemical composition of the precipitation or the affected environment is significantly changed. Saharan dust serves on the one hand as high ionic input leading to an increase of ionic species such as calcium, magnesium or sulfate. On the other hand Saharan dust provides a high alkaline input neutralizing acidic components and causing the pH to increase [3]. Based on these changes in the ion composition, the pH and cross plots of the ion and conductivity balance [4] we tried to develop a method to identify Saharan dust layers in high alpine snow packs. We investigated seasonal snow packs of two high alpine sampling sites situated on the surrounding glaciers of the meteorological Sonnblick observatory serving as a global GAW (Global Atmospheric Watch) station located in the National Park Hohe Tauern in the Austrian Alps. Samples with 10 cm resolution representing the whole winter accumulation period were taken just prior to the start of snow melt at the end of April 2016. In both snow packs two layers with clearly different chemical behavior were observed. In comparison with the aerosol data from the Sonnblick observatory, these layers could be clearly identified as Saharan dust layers. Identified Saharan dust layers in the snow pack allow calculations of the ecological impact of deposited ions, with and without Saharan dust, during snow melt. Furthermore the chemical characteristics for the identification of Saharan dust layers

Measurement of circumsolar ratio in high dust loading regions using a photographic method

Science.gov (United States)

Al-Ansary, Hany; Shafiq, Talha; Rizvi, Arslan; El-Leathy, Abdelrahman

2017-06-01

Performance of concentrating solar power (CSP) plants is highly affected by direct normal irradiance (DNI). However, it is also important to consider circumsolar radiation in any simulation of a CSP plant, especially in desert regions where dust loading in the atmosphere is expected. There are a number of methods to measure circumsolar radiation. However, most of them require expensive instrumentation. This work introduces a simple method to estimate circumsolar radiation. It involves taking high-resolution photographs of the sun and processing them using a computer code that identifies the sun's disk. The code then uses pixel intensities to obtain the solar intensity distribution across the sun's disk and in the aureole region. The solar intensity distribution is then used to obtain the circumsolar ratio (CSR) which represents the shape of the sun. To test this method, numerous photos of the sun were taken during the month of April and September 2016 at King Saud University in Riyadh, Saudi Arabia. Riyadh is a region that is well known for high dust-loading, especially during the summer. Two days of different atmospheric conditions were selected in September for comparative analysis. Results show that this method produces repeatable results, and that the CSR can increase significantly due to high dust loading and passing clouds. The CSR is found to be a strong function of DNI, ranging from about 4.5% at DNI values above 800 W/m2 and increasing to as much as 8.5% when DNI drops to about 400 W/m2, due to passing clouds. Furthermore, the results show that circumsolar ratio tends to be high in the early morning and late afternoon due to the high air mass, while its values tend to be lowest around solar noon when the air mass is lowest.

Comparison of coarse coal dust sampling techniques in a laboratory-simulated longwall section.

Science.gov (United States)

Patts, Justin R; Barone, Teresa L

2017-05-01

Airborne coal dust generated during mining can deposit and accumulate on mine surfaces, presenting a dust explosion hazard. When assessing dust hazard mitigation strategies for airborne dust reduction, sampling is done in high-velocity ventilation air, which is used to purge the mining face and gallery tunnel. In this environment, the sampler inlet velocity should be matched to the air stream velocity (isokinetic sampling) to prevent oversampling of coarse dust at low sampler-to-air velocity ratios. Low velocity ratios are often encountered when using low flow rate, personal sampling pumps commonly used in underground mines. In this study, with a goal of employing mine-ready equipment, a personal sampler was adapted for area sampling of coarse coal dust in high-velocity ventilation air. This was done by adapting an isokinetic nozzle to the inlet of an Institute of Occupational Medicine (Edinburgh, Scotland) sampling cassette (IOM). Collected dust masses were compared for the modified IOM isokinetic sampler (IOM-MOD), the IOM without the isokinetic nozzle, and a conventional dust sampling cassette without the cyclone on the inlet. All samplers were operated at a flow rate typical of personal sampling pumps: 2 L/min. To ensure differences between collected masses that could be attributed to sampler design and were not influenced by artifacts from dust concentration gradients, relatively uniform and repeatable dust concentrations were demonstrated in the sampling zone of the National Institute for Occupational Safety and Health experimental mine gallery. Consistent with isokinetic theory, greater differences between isokinetic and non-isokinetic sampled masses were found for larger dust volume-size distributions and higher ventilation air velocities. Since isokinetic sampling is conventionally used to determine total dust concentration, and isokinetic sampling made a difference in collected masses, the results suggest when sampling for coarse coal dust the IOM-MOD may

The Continuous Monitoring of Desert Dust using an Infrared-based Dust Detection and Retrieval Method

Science.gov (United States)

Duda, David P.; Minnis, Patrick; Trepte, Qing; Sun-Mack, Sunny

2006-01-01

Airborne dust and sand are significant aerosol sources that can impact the atmospheric and surface radiation budgets. Because airborne dust affects visibility and air quality, it is desirable to monitor the location and concentrations of this aerosol for transportation and public health. Although aerosol retrievals have been derived for many years using visible and near-infrared reflectance measurements from satellites, the detection and quantification of dust from these channels is problematic over bright surfaces, or when dust concentrations are large. In addition, aerosol retrievals from polar orbiting satellites lack the ability to monitor the progression and sources of dust storms. As a complement to current aerosol dust retrieval algorithms, multi-spectral thermal infrared (8-12 micron) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Meteosat-8 Spinning Enhanced Visible and Infrared Imager (SEVIRI) are used in the development of a prototype dust detection method and dust property retrieval that can monitor the progress of Saharan dust fields continuously, both night and day. The dust detection method is incorporated into the processing of CERES (Clouds and the Earth s Radiant Energy System) aerosol retrievals to produce dust property retrievals. Both MODIS (from Terra and Aqua) and SEVERI data are used to develop the method.

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

Science.gov (United States)

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

2017-12-01

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

Can We Trust Real Time Measurements of Lung Deposited Surface Area Concentrations in Dust from Powder Nanomaterials?

DEFF Research Database (Denmark)

Levin, Marcus; Witschger, Olivier; Bau, Sebastien

2016-01-01

A comparison between various methods for real-time measurements of lung deposited surface area (LDSA) using spherical particles and powder dust with specific surface area ranging from 0.03 to 112 m2 g-1 was conducted. LDSA concentrations measured directly using Nanoparticle Surface Area Monitor...... gravimetrical filter measurements and specific surface areas. Measurement of LDSA showed very good correlation in measurements of spherical particles (R2 > 0.97, Ratio 1.0 to 1.04). High surface area nanomaterial powders showed a fairly reliable correlation between NSAM and Aerotrak (R2 0...... present. We conclude that there is currently insufficient reliability and comparability between methods in the measurement of LDSA concentrations. Further development is required to enable use of LDSA for reliable dose metric and regulatory enforcement of exposure....

Control of dust hazards in mines

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, V V

1981-09-01

This paper analyzes health hazards associated with air pollution by respirable coal dust which causes pneumoconioses. The following directions in pneumoconioses prevention are discussed: improved protective systems (e.g. respirators), mining schemes optimized from a health hazards point of view, correct determination of the maximum permissible level of respirable dusts, reducing working time. Safety regulations in the USSR on the critical amount of coal dust in the miner respiratory system are insufficient as the 20 g limit is too high and does not guarantee safety. Using regression analysis influence of the factors which cause pneumoconioses is analyzed. This influence is described by an equation which considers the following factors: number of shifts associated with contact of a miner with coal dusts, dust concentration in mine air, amount of air with coal dust being respirated, miner's age, years as miner, coal rank. It is stated that use of the proposed equation (derived by computer calculations) permits the safe working time to be correctly determined considering all factors which cause pneumoconioses.

The Origin and Evolution of Interstellar Dust in the Local and High-redshift Universe

Science.gov (United States)

Dwek, Eliahu

2012-01-01

In this talk I will begin by reviewing our current state of knowledge regarding the origin and evolution of dust in the local solar neighborhood. using chemical evolution models, I will discuss their many different input parameters and their uncertainties. An important consequence of these models is the delayed injection of dust from AGB stars, compared to supernova-condensed dust, into the interstellar medium. I will show that these stellar evolutionary effects on dust composition are manifested in the infrared spectra of local galaxies. The delayed production of dust in AGB stars has also important consequences for the origin of the large amount of dust detected in high-redshift galaxies, when the universe was less that approx. 1 Gyr old. Supernovae may have been the only viable dust sources in those galaxies. Recent observations of sN1987a show a significant mass of dust in the ejecta of this SN. Is that production rate high enough to account for the observed dust mass in these galaxies? If not, what are the alternative viable sources of dust, and how do they depend on the nature of the galaxy (starburst or AGN) and its star formation history .

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

Science.gov (United States)

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

2014-05-01

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

Normal and anomalous diffusion in fluctuations of dust concentration nearby emission source

Science.gov (United States)

Szczurek, Andrzej; Maciejewska, Monika; Wyłomańska, Agnieszka; Sikora, Grzegorz; Balcerek, Michał; Teuerle, Marek

2018-02-01

Particulate matter (PM) is an important component of air. Nowadays, major attention is payed to fine dust. It has considerable environmental impact, including adverse effect on human health. One of important issues regarding PM is the temporal variation of its concentration. The variation contains information about factors influencing this quantity in time. The work focuses on the character of PM concentration dynamics indoors, in the vicinity of emission source. The objective was to recognize between the homogeneous or heterogeneous dynamics. The goal was achieved by detecting normal and anomalous diffusion in fluctuations of PM concentration. For this purpose we used anomalous diffusion exponent, β which was derived from Mean Square Displacement (MSD) analysis. The information about PM concentration dynamics may be used to design sampling strategy, which serves to attain representative information about PM behavior in time. The data analyzed in this work was collected from single-point PM concentration monitoring in the vicinity of seven emission sources in industrial environment. In majority of cases we observed heterogeneous character of PM concentration dynamics. It confirms the complexity of interactions between the emission sources and indoor environment. This result also votes against simplistic approach to PM concentration measurement indoors, namely their occasional character, short measurement periods and long term averaging.

Personal exposure to inhalable cement dust among construction workers.

Science.gov (United States)

Peters, Susan; Thomassen, Yngvar; Fechter-Rink, Edeltraud; Kromhout, Hans

2009-01-01

Objective- A case study was carried out to assess cement dust exposure and its determinants among construction workers and for comparison among workers in cement and concrete production.Methods- Full-shift personal exposure measurements were performed and samples were analysed for inhalable dust and its cement content. Exposure variability was modelled with linear mixed models.Results- Inhalable dust concentrations at the construction site ranged from 0.05 to 34 mg/m(3), with a mean of 1.0 mg/m(3). Average concentration for inhalable cement dust was 0.3 mg/m(3) (GM; range 0.02-17 mg/m(3)). Levels in the ready-mix and pre-cast concrete plants were on average 0.5 mg/m(3) (GM) for inhalable dust and 0.2 mg/m(3) (GM) for inhalable cement dust. Highest concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM = 55 mg/m(3); inhalable cement dust GM = 33 mg/m(3)) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages during reinforcement work and pouring. Most likely other sources were contributing to dust concentrations, particularly at the construction site. Within job groups, temporal variability in exposure concentrations generally outweighed differences in average concentrations between workers. 'Using a broom', 'outdoor wind speed' and 'presence of rain' were overall the most influential factors affecting inhalable (cement) dust exposure.Conclusion- Job type appeared to be the main predictor of exposure to inhalable (cement) dust at the construction site. Inhalable dust concentrations in cement production plants, especially during cleaning tasks, are usually considerably higher than at the construction site.

Grain dust and the lungs.

Science.gov (United States)

Chan-Yeung, M.; Ashley, M. J.; Grzybowski, S.

1978-01-01

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust. Images p1272-a PMID:348288

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

Science.gov (United States)

Zibret, Gorazd

2012-05-01

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

Dust Dynamics Near Planetary Surfaces

Science.gov (United States)

Colwell, Joshua; Hughes, Anna; Grund, Chris

streams observed by Apollo astronauts and potentially also by the Clementine spacecraft. In addition to the Surveyor images of lunar horizon glow and the high altitude streamer measurements, the Apollo 17 Lunar Ejecta and Meteorite surface package detected signals consistent with the impact of relatively slow-moving dust particles that may have been charged dust electrostatically levitated from the surface. There is renewed interest in this near-surface dust environment with plans to return robotic landers and astronauts to the lunar surface. No Apollo-era instruments were specifically designed to detect or measure dust levitated off the lunar surface. One new experiment under study is the Autonomous Lunar Dust Observer (ALDO). ALDO is a high-sensitivity scanning lidar (laser radar) that autonomously maps and records its 3-D dust environment. Flexibility of programmable scan pattern enables ALDO to characterize the dust context in and around experiment sites. Repeated shallow angle scans in a vertical plane enable high vertical resolution studies of dust levitation near the ground. Single elevation angle sector or full azimuth scans enable large-area statistical surveys of the frequency and size of ejecta plumes from micrometeoroid impacts, and vertical or fixed-angle stares enable very high sensitivity dust profiles to extended ranges. It is estimated that backscatter from dust concentrations as low as 1/cm3 can be measured. The concept is equally applicable to surface and atmospheric studies of other airless bodies.

High-resolution provenance of desert dust deposited on Mt. Elbrus, Caucasus in 2009–2012 using snow pit and firn core records

Directory of Open Access Journals (Sweden)

S. Kutuzov

2013-09-01

Full Text Available The first record of dust deposition events on Mt. Elbrus, Caucasus Mountains derived from a snow pit and a shallow firn core is presented for the 2009–2012 period. A combination of isotopic analysis, SEVIRI red-green-blue composite imagery, MODIS atmospheric optical depth fields derived using the Deep Blue algorithm, air mass trajectories derived using the HYSPLIT model and analyses of meteorological data enabled identification of dust source regions with high temporal (hours and spatial (ca. 20–100 km resolution. Seventeen dust deposition events were detected; fourteen occurred in March–June, one in February and two in October. Four events originated in the Sahara, predominantly in northeastern Libya and eastern Algeria. Thirteen events originated in the Middle East, in the Syrian Desert and northern Mesopotamia, from a mixture of natural and anthropogenic sources. Dust transportation from Sahara was associated with vigorous Saharan depressions, strong surface winds in the source region and mid-tropospheric southwesterly flow with daily winds speeds of 20–30 m s−1 at 700 hPa level. Although these events were less frequent than those originating in the Middle East, they resulted in higher dust concentrations in snow. Dust transportation from the Middle East was associated with weaker depressions forming over the source region, high pressure centred over or extending towards the Caspian Sea and a weaker southerly or southeasterly flow towards the Caucasus Mountains with daily wind speeds of 12–18 m s−1 at 700 hPa level. Higher concentrations of nitrates and ammonium characterised dust from the Middle East deposited on Mt. Elbrus in 2009 indicating contribution of anthropogenic sources. The modal values of particle size distributions ranged between 1.98 μm and 4.16 μm. Most samples were characterised by modal values of 2.0–2.8 μm with an average of 2.6 μm and there was no significant difference between dust from the Sahara and

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

Science.gov (United States)

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

2015-06-01

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

Personal exposure to inhalable cement dust among construction workers

International Nuclear Information System (INIS)

Peters, Susan; Kromhout, Hans; Thomassen, Yngvar; Fechter-Rink, Edeltraud

2009-01-01

A case study was carried out in 2006-2007 to assess the actual cement dust exposure among construction workers involved in a full-scale construction project and as a comparison among workers involved in various stages of cement and concrete production. Full-shift personal exposure measurements were performed for several job types. Inhalable dust and cement dust (based on analysis of elemental calcium) concentrations were determined. Inhalable dust exposures at the construction site ranged from 0.05 to 34 mg/m3, with a mean concentration of 1.0 mg/m3. For inhalable cement dust mean exposure was 0.3 mg/m3 (range 0.02-17 mg/m3). Reinforcement and pouring workers had the lowest average concentrations. Inhalable dust levels in the ready-mix and pre-cast concrete plants were, on average, below 0.5 mg/m3 for inhalable dust and below 0.2 mg/m3 for inhalable cement dust. Highest dust concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM=55 mg/m3; inhalable cement dust GM=33 mg/m3) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages of cement during reinforcement work and pouring.

Temporal Trends in Airborne Dust Concentrations at a Large Chrysotile Mine and its Asbestos-enrichment Factories in the Russian Federation During 1951-2001

NARCIS (Netherlands)

Schonfeld, Sara J; Kovalevskiy, Evgeny V; Feletto, Eleonora; Bukhtiyarov, Igor V; Kashanskiy, Sergey V; Moissonier, Monika; Straif, Kurt; McCormack, Valerie A; Schüz, Joachim; Kromhout, Hans

2017-01-01

Objectives: Mining and processing of chrysotile, an established carcinogen, has been undertaken in Asbest, Russian Federation since the late 1800s. Dust concentrations were routinely recorded at the open-pit mine and its asbestos-enrichment factories. We examined the temporal trends in these dust

Suspended dust in Norwegian cities

International Nuclear Information System (INIS)

2001-01-01

According to calculations, at least 80 000 people in Oslo and 8 000 in Trondheim were annoyed by too much suspended dust in 2000. The dust concentration is greatest in the spring, presumably because dust is swirling up from melting snow and ice on the streets. Car traffic is the main source of the dust, except for some of the most highly exposed regions where wood-firing from old stoves contributes up to 70 percent of the dust. National targets for air quality include suspended dust, nitrogen dioxide, sulphur dioxide and benzene. Calculations show that nitrogen dioxide emissions exceeding the limit affected 4 000 people in Oslo and 1 000 people in Trondheim. The sulphur dioxide emissions in the major cities did non exceed the national quality limit; they did exceed the limit in some of the smaller industrial centres. In Trondheim, measurements show that the national limit for benzene was exceeded. Most of the emission of nitrogen dioxide comes from the road traffic. Local air pollution at times causes considerable health- and well-being problems in the larger cities and industrial centres, where a great part of the population may be at risk of early death, infection of the respiratory passage, heart- and lung diseases and cancer

OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

International Nuclear Information System (INIS)

Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan; Zhang, Kai; Zhang, Shaohua

2013-01-01

Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus

Magnetic studies of dusts in the urban environment

International Nuclear Information System (INIS)

Xie, S.

2000-12-01

Dusts are one of the major public health concerns in the urban environment. This study investigates the application of magnetic techniques in the studies of urban dust pollution. Measurements of magnetic properties, element concentrations, and the organic matter content were carried out on Liverpool (UK) street dust and/or Bootle (UK) deposited dust. Mixed dominant ferrimagnetic phases are found in Liverpool street dust although magnetite is probably a major one. The partial susceptibility technique is able to model the contributions of main magnetic components satisfactorily in Liverpool street dust. There are similar spatial distributions for some measurements, such as χLF and Pb, whilst there are different patterns for some measurements, such as χLF and the organic matter content. There are good linear correlations between the organic matter content and some magnetic mineral concentration-related parameters for < 1mm (bulk) samples. Among them, frequency dependent susceptibility (χFD) shows the highest correlation coefficient value. χFD percentage demonstrates a significant correlation with the organic matter content for size fraction and bulk samples. This suggests that re-entrainment of soil is probably a major source of the organic material present in street dust. The ratio χARM /SIRM shows a highly significant correlation with the organic matter content for <150μm fraction samples. The study demonstrates that the simple, rapid, and non-destructive magnetic measurements may be used as proxies for the organic matter content in street dust. Associations between magnetic properties and element concentrations are investigated by using correlation analysis and factor analysis, which may be a potential approach for source identification of magnetic material in the environment. The study suggests that ferrimagnetic minerals are the dominant magnetic component in Bootle dust samples. Both studied sites show similar magnetic properties, but they can be

Charging of Dust Grains in a Nuclear-Induced Plasma at High Pressures

International Nuclear Information System (INIS)

Pal’, A. F.; Starostin, A. N.; Filippov, A. V.

2001-01-01

The process of dust-grain charging in plasmas produced by radioactive decay products or spontaneous fission fragments in air and xenon at high pressures is studied numerically in the hydrodynamic approximation. It is shown that, at sufficiently high rates of gas ionization, the dust grains in air are charged by electrons rather than ions, so that the grain charge in air is comparable to that in electropositive gases. The results of numerical calculations based on a complete model agree well with the experimental data. The time evolution of the grain charge is investigated, and the characteristic time scales on which the grains acquire an electric charge are established. The validity of approximate theories of dust-grain charging in electropositive and electronegative gases at high pressures is examined

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

Science.gov (United States)

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

2014-12-01

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

Air-conditioner filters enriching dust mites allergen.

Science.gov (United States)

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

2015-01-01

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

Ways of far-distance dust transport onto Caucasian glaciers and chemical composition of snow on the Western plateau of Elbrus

Directory of Open Access Journals (Sweden)

S. S. Kutuzov

2014-01-01

Full Text Available We present and discuss the chronology of dust deposition events documented by the shallow firn and ice cores extracted on the Western Plateau, Mt. Elbrus (5150 m a.s.l. in 2009, 2012 and 2013. Snow and ice samples were analysed for major ions and minor element concentrations including heavy metals. Dust layers are formed on the surface of the glaciers as a result of atmospheric transport of mineral dust and aerosol particles to the Caucasus region. Satellite imagery (SEVIRI, trajectory models, and meteorological data were used for accurate dating of each the dust layers revealed in the ice cores. Then we tried to determine origins of the dust clouds and to investigate their transport pathways with high resolution (50–100 km. It was found that the desert dust is deposited on Caucasus glaciers 3–7 times in a year and it comes mainly from deserts of the Middle East and more rarely from the Northern Sahara desert. For the first time average annual dust flux (264 µg/cm2 per a year and average mass concentration (1.7 mg/kg over the period 2007–2013 were calculated for this region. The deposition of dust resulted in elevated concentrations consists of mostly ions, especially Ca2+, Mg2+, K+, and sulphates. Dust originated from various sources in the Middle East, including Mesopotamia, or similar dust clouds passing over the Middle East are characterised by high concentrations of nitrates and ammonia that may be related to atmospheric transport of ammonium from agricultural lands that may explain high concentrations of ammonium in the dust originating from this region. Mean values of crustal enrichment factors (EF for the measured minor elements including heavy metals were calculated. We believe that high content of Cu, Zn and Cd can be a result of possible contribution from anthropogenic sources. Studies of the Caucasus ice cores may allow obtaining new independent data on the atmosphere circulation and high-altitude environment of this region.

Fresh gasoline emissions, not paved road dust, alter cardiac repolarization in ApoE-/- mice.

Science.gov (United States)

Campen, Matthew J; McDonald, Jacob D; Reed, Matthew D; Seagrave, Jeanclare

2006-01-01

Fresh vehicular emissions potentially represent a ubiquitous environmental concern for cardiovascular health. We compared electrocardiographic effects of fresh gasoline engine emissions with resuspended paved road dust in a mouse model of coronary insufficiency. Apolipoprotein E (ApoE)-/- mice on a high fat diet were exposed by whole-body inhalation to either gasoline emissions at 60 microg/m3 particulate matter (PM), an equivalent atmosphere with particles filtered out of the whole exhaust, or paved road dust at 0.5 and 3.5 mg /m3 for 6 h/d for 3 d. Radiotelemetry recordings of electrocardiogram (ECG) were analyzed for changes in T-wave morphology (QT interval, T-wave amplitude, and T-wave Area). Following exposures, lung lavage and blood samples were obtained to assay for markers of pulmonary and systemic inflammation. No exposure induced significant changes in heart rate and only the high concentration of road dust induced signs of pulmonary inflammation. T-wave area exhibited significant deviation from baseline values during exposure to gasoline exhaust particulates, but not to either concentration of road dust or gasoline emissions sans particulates. Gasoline-exposed mice demonstrated elevated plasma endothelin-1, but did not cause systemic inflammation. These data support the hypothesis that freshly-generated engine emissions, as opposed to resuspended paved road dust, may drive cardiac effects that have been observed at road-sides in the environment. The absence of ECG effects for both very high concentrations of road dust PM and equivalent concentrations of the vapor/gas phase of gasoline engine exhaust further indicate the specific risk conferred by fresh vehicular PM.

Experimental investigations of the minimum ignition energy and the minimum ignition temperature of inert and combustible dust cloud mixtures

Energy Technology Data Exchange (ETDEWEB)

Addai, Emmanuel Kwasi, E-mail: emmanueladdai41@yahoo.com; Gabel, Dieter; Krause, Ulrich

2016-04-15

Highlights: • Ignition sensitivity of a highly flammable dust decreases upon addition of inert dust. • Minimum ignition temperature of a highly flammable dust increases when inert concentration increase. • Minimum ignition energy of a highly flammable dust increases when inert concentration increase. • The permissible range for the inert mixture to minimize the ignition risk lies between 60 to 80%. - Abstract: The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety (moderation). This is achieved by adding an inert material to a highly combustible material in order to decrease the ignition sensitivity of the combustible dust. The presented paper deals with the experimental investigation of the influence of adding an inert dust on the minimum ignition energy and the minimum ignition temperature of the combustible/inert dust mixtures. The experimental investigation was done in two laboratory scale equipment: the Hartmann apparatus and the Godbert-Greenwald furnace for the minimum ignition energy and the minimum ignition temperature test respectively. This was achieved by mixing various amounts of three inert materials (magnesium oxide, ammonium sulphate and sand) and six combustible dusts (brown coal, lycopodium, toner, niacin, corn starch and high density polyethylene). Generally, increasing the inert materials concentration increases the minimum ignition energy as well as the minimum ignition temperatures until a threshold is reached where no ignition was obtained. The permissible range for the inert mixture to minimize the ignition risk lies between 60 to 80%.

Experimental investigations of the minimum ignition energy and the minimum ignition temperature of inert and combustible dust cloud mixtures

International Nuclear Information System (INIS)

Addai, Emmanuel Kwasi; Gabel, Dieter; Krause, Ulrich

2016-01-01

Highlights: • Ignition sensitivity of a highly flammable dust decreases upon addition of inert dust. • Minimum ignition temperature of a highly flammable dust increases when inert concentration increase. • Minimum ignition energy of a highly flammable dust increases when inert concentration increase. • The permissible range for the inert mixture to minimize the ignition risk lies between 60 to 80%. - Abstract: The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety (moderation). This is achieved by adding an inert material to a highly combustible material in order to decrease the ignition sensitivity of the combustible dust. The presented paper deals with the experimental investigation of the influence of adding an inert dust on the minimum ignition energy and the minimum ignition temperature of the combustible/inert dust mixtures. The experimental investigation was done in two laboratory scale equipment: the Hartmann apparatus and the Godbert-Greenwald furnace for the minimum ignition energy and the minimum ignition temperature test respectively. This was achieved by mixing various amounts of three inert materials (magnesium oxide, ammonium sulphate and sand) and six combustible dusts (brown coal, lycopodium, toner, niacin, corn starch and high density polyethylene). Generally, increasing the inert materials concentration increases the minimum ignition energy as well as the minimum ignition temperatures until a threshold is reached where no ignition was obtained. The permissible range for the inert mixture to minimize the ignition risk lies between 60 to 80%.

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

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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.

Dust Effect on The Performance of Optical Wireless Communication System

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Fadel Abdul-Zahra Murad

2017-11-01

Full Text Available In this paper wireless optical communication system (FSO is designed through the use of software (Optisystem . The paper also study  the effect of atmospheric dust on the performance of communication system (FSO, the effect of dust concentration on the visibility by taking a different concentrations of dust (9, 20, 40, 60, 80 100, 120 gm / month / m2 . The effect of the visibility on the attenuation of dust concentration on each of these concentrations , and calculate attenuation of dust for the  wavelengths  (784 nm, 1550 nm. The Paper also deals with effect of the transmitted laser  power on the transmitter range (propagation distance where five different values of transmitted laser power (10mw, 20mw, 30mw, 40mw, 50mw are taken  and the study calculates the maximum transmitter range of  each value of the transmitted power under the influence of attenuation atmospheric dust concentrations for each concentration of dust used and also for the two wavelengths (1550nm, 784nm.

THE MEASUREMENT AND DISTRIBUTION OF WOOD DUST

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Andrea Rosario Proto

2010-03-01

Full Text Available In Italy, the woodworking industry presents many issues in terms of occupational health and safety. This study on exposure to wood dust could contribute to the realization of a prevention model in order to limit exposure to carcinogenic agents to the worker. The sampling methodology illustrated the analysis of dust emissions from the woodworking machinery in operation throughout the various processing cycles. The quantitative and qualitative assessment of exposure was performed using two different methodologies. The levels of wood dust were determined according to EN indications and sampling was conducted using IOM and Cyclon personal samplers. The qualitative research of wood dust was performed using an advanced laser air particle counter. This allowed the number of particles present to be counted in real time. The results obtained allowed for an accurate assessment of the quality of the dust emitted inside the workplace during the various processing phases. The study highlighted the distribution of air particles within the different size classes, the exact number of both thin and ultra-thin dusts, and confirmed the high concentration of thin dust particles which can be very harmful to humans.

Dust in planetary nebulae

International Nuclear Information System (INIS)

Mathis, J.S.

1978-01-01

The author's review concentrates on theoretical aspects of dust in planetary nebulae (PN). He considers the questions: how much dust is there is PN; what is its composition; what effects does it have on the ionization structure, on the dynamics of the nebula. (Auth.)

Fully kinetic simulation of ion acoustic and dust-ion acoustic waves

International Nuclear Information System (INIS)

Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.

2011-01-01

A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.

Direct-reading inhalable dust monitoring--an assessment of current measurement methods.

Science.gov (United States)

Thorpe, Andrew; Walsh, Peter T

2013-08-01

Direct-reading dust monitors designed specifically to measure the inhalable fraction of airborne dust are not widely available. Current practice therefore often involves comparing the response of photometer-type dust monitors with the concentration measured with a reference gravimetric inhalable sampler, which is used to adjust the dust monitor measurement. However, changes in airborne particle size can result in significant errors in the estimation of inhalable concentration by this method. The main aim of this study was to assess how these dust monitors behave when challenged with airborne dust containing particles in the inhalable size range and also to investigate alternative dust monitors whose response might not be as prone to variations in particle size or that could be adapted to measure inhalable dust concentration. Several photometer-type dust monitors and a Respicon TM, tapered element oscillating microbalance (TEOM) personal dust monitor (PDM) 3600, TEOM 1400, and Dustrak DRX were assessed for the measurement of airborne inhalable dust during laboratory and field trials. The PDM was modified to allow it to sample and measure larger particles in the inhalable size range. During the laboratory tests, the dust monitors and reference gravimetric samplers were challenged inside a large dust tunnel with aerosols of industrial dusts known to present an inhalable hazard and aluminium oxide powders with a range of discrete particle sizes. A constant concentration of each dust type was generated and peak concentrations of larger particles were periodically introduced to investigate the effects of sudden changes in particle size on monitor calibration. The PDM, Respicon, and DataRam photometer were also assessed during field trials at a bakery, joinery, and a grain mill. Laboratory results showed that the Respicon, modified PDM, and TEOM 1400 observed good linearity for all types of dust when compared with measurements made with a reference IOM sampler; the

Recirculation effect of Chilean copper smelting dust with high impurities contents on the impurity distributions during smelting process; Efecto de la recirculacion de polvo de fundicion de cobre de Chile con altos contenidos de impurezas en la distribucion de impurezas durante el proceso de fusion

Energy Technology Data Exchange (ETDEWEB)

Montenegro, V.; Sano, H.; Fujisawa, T.

2010-07-01

Usually, dust generated during the copper smelting process by the Teniente Converter and the Flash Smelting Furnaces in Chile, contains high concentrations of copper, zinc, arsenic, antimony and other metals. In general, the dust is recirculated to the smelting process or it is directed to hydrometallurgical process for recovery and stabilization. However, in recent years the generation of dust has increased because of the degradation of the quality of the concentrate. In addition, the environmental regulations have become stricter. It is therefore desirable to understand the behavior of those elements, when the smelting process operates with recirculation of dust. In this study, the effect of dust recirculation to smelting process on the distribution among the matte, slag and gas phases was evaluated, as a function of matte grade, amount of recirculated dust, oxygen enrichment and temperature. It was found that the concentration in the matte of the impurities such as arsenic, antimony and bismuth, increased slightly with recirculation of dust. On the other hand, the concentration of lead and zinc depend of the direct recirculation of dust to the process. Additionally, it was found that high concentrations of arsenic and antimony in the dust may lead to the formation and precipitation of copper arsenates and other metals (speiss), which may generates important operational problems. (Author) 15 refs.

Fipronil and its degradates in indoor and outdoor dust

Science.gov (United States)

Mahler, B.J.; Van Metre, P.C.; Wilson, J.T.; Musgrove, M.; Zaugg, S.D.; Burkhardt, M.R.

2009-01-01

Fipronil is a potent insecticide used for control of termites, fleas, roaches, ants, and other pests. We measured fipronil, fipronil sulfide, and desulfinyl fipronil concentrations in indoor and outdoor dust from 24 residences in Austin, Texas. At least one of these three fipronil compounds was detected in every sample. Fipronil accounted for most of the total fipronil (T-fipronil; fipronil+desulfinyl fipronil+fipronil sulfide), followed by desulfinyl fipronil and fipronil sulfide. Nineteen of 24 samples of indoor dust had T-fipronil concentrations less than 270 ??g/kg; the remaining five had concentrations from 1320 to 14,200 ??g/kg. All three of the residences with a dog on which a flea-control product containing fipronil was used were among the five residences with elevated fipronil concentrations. In outdoor dust, all concentrations of T-fipronil were less than 70??g/kg with one exception (430??g/kg). For every residence, the concentration of T-fipronil in indoor dust exceeded that in outdoor dust, and the median concentration of T-fipronil was 15 times higher indoors than outdoors.

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

International Nuclear Information System (INIS)

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

2015-01-01

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. - Highlights: • Geographical variation in house dust Pb concentrations were observed. • Dust Pb concentrations were not associated with house age and decoration materials. • Soil, coal combustion, and site specific pollution were potential Pb sources. • Pb bearing particles were identified by SEM-EDX. - The variations of Pb in Chinese villager house dust were controlled by outdoor soil, coal combustion, and site specific pollution sources.

Nasal lavage cellularity, grain dust, and airflow obstruction.

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Blaski, C A; Watt, J L; Quinn, T J; Thorne, P S; Schwartz, D A

1996-04-01

To evaluate the clinical utility of nasal lavage (NL), we performed post-work shift NL on 172 grain workers and 78 postal worker control subjects. The grain worker group included a higher percentage of current smokers (25.7% vs 16.7%) and a lower percentage of former smokers (21.15% vs 35.9%) compared with the postal workers. The control subjects included more female workers and were slightly older than the grain workers. Compared with the postal workers, the grain workers were exposed to significantly greater concentrations of total dust (0.1 +/- 0.0 vs 6.8 +/- 1.4 mg/m3; mean +/- SEM) and total endotoxin (4.3 +/- 0.8 vs 2,372.4 +/- 653.8 endotoxin units/m3). NL from gain workers showed a higher concentration of total cells (55,000 +/- 14,000 vs 25,000 +/- 5,000 cells per milliliter; p=0.03), a higher concentration of squamous epithelial cells (17,029.0 +/- 4,177 .0 vs 7,103.7 +/- 1,479.8 cells per milliliter; p=0.03), and a higher concentration of neutrophils (40,058.0 +/- 12,803.2 vs 17,891.0 +/- 3,822.3 cells per milliliter; p=0.10) compared with postal workers. Importantly, these differences in NL cellularity between grain workers and postal workers were observed within the three strata of smokers. To further assess the importance of total cells, squamous epithelial cells, and neutrophils in the NL fluid of grain workers, we investigated the relationship between these cell concentrations and (1) measures of dust and endotoxin exposure during the work shift. (2) spirometric measures of airflow obtained immediately before the NL, and (3) work-related respiratory symptoms. The concentration of total cells, the concentration of squamous epithelial cells, or the concentration of neutrophils in the NL was not associated with ambient levels of dust or endotoxin, with baseline or cross-shift changes in lung function, or with work-related respiratory symptoms. These findings suggest that increased NL cellularity may be seen in workers exposed to high dust levels

Simulating the meteorology and PM10 concentrations in Arizona dust storms using the Weather Research and Forecasting model with Chemistry (Wrf-Chem).

Science.gov (United States)

Hyde, Peter; Mahalov, Alex; Li, Jialun

2018-03-01

Nine dust storms in south-central Arizona were simulated with the Weather Research and Forecasting with Chemistry model (WRF-Chem) at 2 km resolution. The windblown dust emission algorithm was the Air Force Weather Agency model. In comparison with ground-based PM 10 observations, the model unevenly reproduces the dust-storm events. The model adequately estimates the location and timing of the events, but it is unable to precisely replicate the magnitude and timing of the elevated hourly concentrations of particles 10 µm and smaller ([PM 10 ]).Furthermore, the model underestimated [PM 10 ] in highly agricultural Pinal County because it underestimated surface wind speeds and because the model's erodible fractions of the land surface data were too coarse to effectively resolve the active and abandoned agricultural lands. In contrast, the model overestimated [PM 10 ] in western Arizona along the Colorado River because it generated daytime sea breezes (from the nearby Gulf of California) for which the surface-layer speeds were too strong. In Phoenix, AZ, the model's performance depended on the event, with both under- and overestimations partly due to incorrect representation of urban features. Sensitivity tests indicate that [PM 10 ] highly relies on meteorological forcing. Increasing the fraction of erodible surfaces in the Pinal County agricultural areas improved the simulation of [PM 10 ] in that region. Both 24-hr and 1-hr measured [PM 10 ] were, for the most part, and especially in Pinal County, extremely elevated, with the former exceeding the health standard by as much as 10-fold and the latter exceeding health-based guidelines by as much as 70-fold. Monsoonal thunderstorms not only produce elevated [PM 10 ], but also cause urban flash floods and disrupt water resource deliveries. Given the severity and frequency of these dust storms, and conceding that the modeling system applied in this work did not produce the desired agreement between simulations and

A STUDY OF FISCHER 344 RATS EXPOSED TO SILICA DUST FOR SIX MONTHS AT CONCENTRATIONS OF 0, 2, 10 OR 20 MG / M3.

Energy Technology Data Exchange (ETDEWEB)

KUTZMAN,R.S.

1984-02-01

The major objective of this study was to relate the results of a series of functional tests to the compositional and structural alterations in the rat lung induced by subchronic exposure to silica dust. Fischer-344 rats were exposed for 6 hours/day, 5 days/week for 6 months to either 0, 2, 10, or 20 mg SiO{sub 2}/m{sup 3}. The general appearance of the exposed rats was not different from that of the controls. Interestingly, female rats exposed to silica dust, at all tested concentrations, gained more weight than the controls. The lung weight and the lung-to-body weight ratio was greater in the male rats exposed to the highest concentration of silica dust.

DUST-BATHING BEHAVIORS OF AFRICAN HERBIVORES AND THE POTENTIAL RISK OF INHALATIONAL ANTHRAX.

Science.gov (United States)

Barandongo, Zoe R; Mfune, John K E; Turner, Wendy C

2018-01-01

:  Anthrax in herbivorous wildlife and livestock is generally assumed to be transmitted via ingestion or inhalation of Bacillus anthracis spores. Although recent studies have highlighted the importance of the ingestion route for anthrax transmission, little is known about the inhalational route in natural systems. Dust bathing could aerosolize soilborne pathogens such as B. anthracis, exposing dust-bathing individuals to inhalational infections. We investigated the potential role of dust bathing in the transmission of inhalational anthrax to herbivorous wildlife in Etosha National Park, Namibia, an area with endemic seasonal anthrax outbreaks. We 1) cultured soils from dust-bathing sites for the presence and concentration of B. anthracis spores, 2) monitored anthrax carcass sites, the locations with the highest B. anthracis concentrations, for evidence of dust bathing, including a site where a zebra died of anthrax on a large dust bath, and 3) characterized the ecology and seasonality of dust bathing in plains zebra ( Equus quagga), blue wildebeest ( Connochaetes taurinus), and African savanna elephant ( Loxodonta africana) using a combination of motion-sensing camera traps and direct observations. Only two out of 83 dust-bath soils were positive for B. anthracis, both with low spore concentrations (≤20 colony-forming units per gram). We also detected no evidence of dust baths occurring at anthrax carcass sites, perhaps due to carcass-induced changes in soil composition that may deter dust bathing. Finally, despite observing some seasonal variation in dust bathing, preliminary evidence suggests that the seasonality of dust bathing and anthrax mortalities are not correlated. Thus, although dust bathing creates a dramatic cloud of aerosolized soil around an individual, our microbiologic, ecologic, and behavioral results in concert demonstrate that dust bathing is highly unlikely to transmit inhalational anthrax infections.

Modulation of ice ages via precession and dust-albedo feedbacks

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Ralph Ellis

2016-11-01

Full Text Available We present here a simple and novel proposal for the modulation and rhythm of ice-ages and interglacials during the late Pleistocene. While the standard Milankovitch-precession theory fails to explain the long intervals between interglacials, these can be accounted for by a novel forcing and feedback system involving CO2, dust and albedo. During the glacial period, the high albedo of the northern ice sheets drives down global temperatures and CO2 concentrations, despite subsequent precessional forcing maxima. Over the following millennia more CO2 is sequestered in the oceans and atmospheric concentrations eventually reach a critical minima of about 200 ppm, which combined with arid conditions, causes a die-back of temperate and boreal forests and grasslands, especially at high altitude. The ensuing soil erosion generates dust storms, resulting in increased dust deposition and lower albedo on the northern ice sheets. As northern hemisphere insolation increases during the next Milankovitch cycle, the dust-laden ice-sheets absorb considerably more insolation and undergo rapid melting, which forces the climate into an interglacial period. The proposed mechanism is simple, robust, and comprehensive in its scope, and its key elements are well supported by empirical evidence.

Studies on airborne dust particles by neutron activation analysis

International Nuclear Information System (INIS)

Aoki, Atsushi; Ishii, Taka; Tomiyama, Tsuyoshi; Yamamoto, Isao.

1974-01-01

Neutron activation analysis was performed on the airborne dust particles collected at six places with different contaminating circumstances in Kyoto city and the suburbs of Okayama city, using an open type low volume air sampler with a membrance filter attached. Radioactivation by neutrons was performed with the reactor in the Research Reactor Institute of Kyoto University. Short half-life nuclides activated by thermal neutrons were measured. The concentration of airborne dust was usually high in November and December, while Na, Mn, K, etc. probably owing to soil origin showed similar seasonal change to the dust particles, as expected. The concentrations Cl and Br were in proportion to traffic volume, and it was considered to be caused by the exhaust gas from cars. Zn, V. et. were thick in factory areas, which seemed to show the relationship with oil fuel consumption. (Kobatake, H.)

Respirable quartz hazard associated with coal mine roof bolter dust

International Nuclear Information System (INIS)

Joy, G.J.; Beck, T.W.; Listak, J.M.

2010-01-01

Pneumoconiosis has been reported to be increasing among underground coal miners in the Southern Appalachian Region. The National Institute for Occupational Safety and Health conducted a study to examine the particle size distribution and quartz content of dust generated by the installation of roof bolts in mines. Forty-six bulk samples of roof bolting machine pre-cleaner cyclone dump dust and collector box dust were collected from 26 underground coal mines. Real-time and integrated airborne respirable dust concentrations were measured on 3 mining sections in 2 mines. The real-time airborne dust concentrations profiles were examined to identify any concentration changes that might be associated with pre-cleaner cyclone dust discharge events. The study showed that bolter dust is a potential inhalation hazard due to the fraction of dust less than 10 μm in size, and the quartz content of the dust. The pre-cleaner cyclone dust was significantly larger than the collector box dust, indicating that the pre-cleaner functioned properly in removing the larger dust size fraction from the airstream. However, the pre-cleaner dust still contained a substantial amount of respirable dust. It was concluded that in order to maintain the effectiveness of a roof bolter dust collector, periodic removal of dust is required. Appropriate work procedures and equipment are necessary to minimize exposure during this cleaning task. 13 refs., 3 tabs., 2 figs.

Can Asian Dust Trigger Phytoplankton Blooms in the Oligotrophic Northern South China Sea?

Science.gov (United States)

Wang, Sheng Hsiang; Hsu, Nai-Yung Christina; Tsay, Si-Chee; Lin, Neng-Huei; Sayer, Andrew M.; Huang, Shih-Jen; Lau, William K. M.

2012-01-01

Satellite data estimate a high dust deposition flux (approximately 18 g m(exp-2 a(exp-1) into the northern South China Sea (SCS). However, observational evidence concerning any biological response to dust fertilization is sparse. In this study, we combined long-term aerosol and chlorophyll-a (Chl-a) measurements from satellite sensors (MODIS and SeaWiFS) with a 16-year record of dust events from surface PM10 observations to investigate dust transport, flux, and the changes in Chl-a concentration over the northern SCS. Our result revealed that readily identifiable strong dust events over this region, although relatively rare (6 cases since 1994) and accounting for only a small proportion of the total dust deposition (approximately 0.28 g m(exp-2 a(exp-1), do occur and could significantly enhance phytoplankton blooms. Following such events, the Chl-a concentration increased up to 4-fold, and generally doubled the springtime background value (0.15 mg m(exp-3). We suggest these heavy dust events contain readily bioavailable iron and enhance the phytoplankton growth in the oligotrophic northern SCS.

Whither Cometary Dust?

Science.gov (United States)

Lisse, Carey M.

2010-10-01

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

Asian dust events of April 1998

Science.gov (United States)

Husar, R.B.; Tratt, D.M.; Schichtel, B.A.; Falke, S.R.; Li, F.; Jaffe, D.; Gasso, S.; Gill, T.; Laulainen, N.S.; Lu, F.; Reheis, M.C.; Chun, Y.; Westphal, D.; Holben, B.N.; Gueymard, C.; McKendry, I.; Kuring, N.; Feldman, G.C.; McClain, C.; Frouin, R.J.; Merrill, J.; DuBois, D.; Vignola, F.; Murayama, T.; Nickovic, S.; Wilson, W.E.; Sassen, K.; Sugimoto, N.; Malm, W.C.

2001-01-01

On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UV cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 ??g/m3 with local peaks >100 ??g/m3. The dust mass mean diameter was 2-3 ??m, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative

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

International Nuclear Information System (INIS)

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

2017-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-02-15

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

Particle size fractionation and human exposure of polybrominated diphenyl ethers in indoor dust from Chicago.

Science.gov (United States)

Wei, Hua; Turyk, Mary; Cali, Salvatore; Dorevitch, Samuel; Erdal, Serap; Li, An

2009-11-01

The objective of this study was to investigate the concentration level, the mass distribution based on dust particle size, and the associated human exposure of polybrominated diphenyl ethers (PBDEs) in indoor dust. The total concentration of 13 PBDEs Sigma(13)(BDEs) was found to be 500-6,944 ng/g in indoor dusts, 4,000 ng/g in car interior dust, 260-300 ng/g in outdoor ambient air particles, 30 ng/g in carpet fibers, and as high as 0.5% in carpet padding. Selected dust samples were fractionated based on particle size, and over 80% of the Sigma(13)BDEs were associated with particles exposure of Americans to PBDEs via hand-to-mouth transfer of house dust was estimated under the central tendency exposure and reasonable maximum exposure scenarios. The results suggest that ingestion of PBDE-laden house dust via hand-to-mouth contact is likely a significant exposure pathway, especially for children.

The fate of injectant coal in blast furnaces: The origin of extractable materials of high molecular mass in blast furnace carryover dusts

Energy Technology Data Exchange (ETDEWEB)

Dong, S.N.; Wu, L.; Paterson, N.; Herod, A.A.; Dugwell, D.R.; Kandiyoti, R. [University of London Imperial College of Science & Technology, London (United Kingdom). Dept. of Chemical Engineering

2005-07-01

The aim of the work was to investigate the fate of injectant coal in blast furnaces and the origin of extractable materials in blast furnace carryover dusts. Two sets of samples including injectant coal and the corresponding carryover dusts from a full sized blast furnace and a pilot scale rig have been examined. The samples were extracted using 1-methyl-2-pyrrolidinone (NMP) solvent and the extracts studied by size exclusion chromatography (SEC). The blast furnace carryover dust extracts contained high molecular weight carbonaceous material, of apparent mass corresponding to 10{sup 7}-10{sup 8} u, by polystyrene calibration. In contrast, the feed coke and char prepared in a wire mesh reactor under high temperature conditions did not give any extractable material. Meanwhile, controlled combustion experiments in a high-pressure wire mesh reactor suggest that the extent of combustion of injectant coal in the blast furnace tuyeres and raceways is limited by time of exposure and very low oxygen concentration. It is thus likely that the extractable, soot-like material in the blast furnace dust originated in tars is released by the injectant coal. Our results suggest that the unburned tars were thermally altered during the upward path within the furnace, giving rise to the formation of heavy molecular weight (soot-like) materials.

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

Science.gov (United States)

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

2012-09-01

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

Insights into a dust event transported through Beijing in spring 2012: Morphology, chemical composition and impact on surface aerosols

Energy Technology Data Exchange (ETDEWEB)

Hu, Wei [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502 (Japan); Niu, Hongya [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Key Laboratory of Resource Exploration Research of Hebei Province, Hebei University of Engineering, Handan, Hebei 056038 (China); Zhang, Daizhou [Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502 (Japan); Wu, Zhijun [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Chen, Chen [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Beijing Municipal Environmental Monitoring Center, Beijing 100044 (China); Wu, Yusheng; Shang, Dongjie [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Hu, Min, E-mail: minhu@pku.edu.cn [State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China)

2016-09-15

Multiple approaches were used to investigate the evolution of surface aerosols in Beijing during the passage of a dust event at high altitude, which was from the Gobi areas of southern Mongolia and covered a wide range of North China. Single particle analysis with electron microscope showed that the majority of coarse particles were mineral ones, and most of them were in the size range of 1–7 μm with a peak of number concentration at about 3.5 μm. Based on elemental composition and morphology, the mineral particles could be classified into several groups, including Si-rich (71%), Ca-rich (15%), Fe-rich (6%), and halite-rich (2%), etc., and they were the main contributors to the aerosol optical depth as the dust occurred. The size distributions of surface aerosols were significantly affected by the dust intrusion. The average number concentration of accumulation mode particles during the event was about 400 cm{sup −3}, which was much lower than that in heavily polluted days (6300 cm{sup −3}). At the stage of floating dust, the number concentration of accumulation mode particles decreased, and coarse particles contributed to total volume concentration of particulate matter as much as 90%. The accumulation mode particles collected in this stage were mostly in the size range of 0.2–0.5 μm, and were rectangular or spherical. They were considered to be particles consisting of ammonium sulfate. New particle formation (NPF) was observed around noon in the three days during the dust event, indicating that the passage of the dust was probably favorable for NPF. - Highlights: • A dust event transported at high altitude through Beijing was investigated. • The dust event caused high variation in surface aerosol number concentrations. • Fine particles in the floating dust period probably consisted of ammonium sulfate. • Passage of the dust induced a favorable condition for new particle formation.

Insights into a dust event transported through Beijing in spring 2012: Morphology, chemical composition and impact on surface aerosols

International Nuclear Information System (INIS)

Hu, Wei; Niu, Hongya; Zhang, Daizhou; Wu, Zhijun; Chen, Chen; Wu, Yusheng; Shang, Dongjie; Hu, Min

2016-01-01

Multiple approaches were used to investigate the evolution of surface aerosols in Beijing during the passage of a dust event at high altitude, which was from the Gobi areas of southern Mongolia and covered a wide range of North China. Single particle analysis with electron microscope showed that the majority of coarse particles were mineral ones, and most of them were in the size range of 1–7 μm with a peak of number concentration at about 3.5 μm. Based on elemental composition and morphology, the mineral particles could be classified into several groups, including Si-rich (71%), Ca-rich (15%), Fe-rich (6%), and halite-rich (2%), etc., and they were the main contributors to the aerosol optical depth as the dust occurred. The size distributions of surface aerosols were significantly affected by the dust intrusion. The average number concentration of accumulation mode particles during the event was about 400 cm"−"3, which was much lower than that in heavily polluted days (6300 cm"−"3). At the stage of floating dust, the number concentration of accumulation mode particles decreased, and coarse particles contributed to total volume concentration of particulate matter as much as 90%. The accumulation mode particles collected in this stage were mostly in the size range of 0.2–0.5 μm, and were rectangular or spherical. They were considered to be particles consisting of ammonium sulfate. New particle formation (NPF) was observed around noon in the three days during the dust event, indicating that the passage of the dust was probably favorable for NPF. - Highlights: • A dust event transported at high altitude through Beijing was investigated. • The dust event caused high variation in surface aerosol number concentrations. • Fine particles in the floating dust period probably consisted of ammonium sulfate. • Passage of the dust induced a favorable condition for new particle formation.

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

KAUST Repository

Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

2016-01-01

Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

Sensitivity of MENA Tropical Rainbelt to Dust Shortwave Absorption: A High Resolution AGCM Experiment

KAUST Repository

Bangalath, Hamza Kunhu

2016-06-13

Shortwave absorption is one of the most important, but the most uncertain, components of direct radiative effect by mineral dust. It has a broad range of estimates from different observational and modeling studies and there is no consensus on the strength of absorption. To elucidate the sensitivity of the Middle East and North Africa (MENA) tropical summer rainbelt to a plausible range of uncertainty in dust shortwave absorption, AMIP-style global high resolution (25 km) simulations are conducted with and without dust, using the High-Resolution Atmospheric Model (HiRAM). Simulations with dust comprise three different cases by assuming dust as a very efficient, standard and inefficient absorber. Inter-comparison of these simulations shows that the response of the MENA tropical rainbelt is extremely sensitive to the strength of shortwave absorption. Further analyses reveal that the sensitivity of the rainbelt stems from the sensitivity of the multi-scale circulations that define the rainbelt. The maximum response and sensitivity are predicted over the northern edge of the rainbelt, geographically over Sahel. The sensitivity of the responses over the Sahel, especially that of precipitation, is comparable to the mean state. Locally, the response in precipitation reaches up to 50% of the mean, while dust is assumed to be a very efficient absorber. Taking into account that Sahel has a very high climate variability and is extremely vulnerable to changes in precipitation, the present study suggests the importance of reducing uncertainty in dust shortwave absorption for a better simulation and interpretation of the Sahel climate.

Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

Science.gov (United States)

Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

2011-01-01

Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece.

Science.gov (United States)

Besis, Athanasios; Katsoyiannis, Athanasios; Botsaropoulou, Elisavet; Samara, Constantini

2014-05-01

Polybrominated Diphenyl Ethers (PBDEs) are ubiquitous in the indoor environment owing to their use in consumer products and various studies around the world have found higher concentrations indoors than outdoors. Central air conditioner (A/C) systems have been widely used in many workplaces, therefore, studying of PBDEs in central A/C filter dust is useful to better understand the occurrences and health implications of PBDEs in indoor environments. The present study examined the occurrence of PBDEs in central A/C filter dust collected from various workplaces (n = 20) in Thessaloniki, Greece. The sum concentrations of 21 target congeners (∑21PBDE) in A/C dust ranged between 84 and 4062 ng g(-1) with a median value of 1092 ng g(-1), while BDE-209 was found to be the most abundant BDE congener. The daily intake via dust ingestion of PBDEs estimated for the employees of the occupational settings ranged from 3 to 45 ng day(-1) (median 12 ng day(-1)). Copyright © 2014 Elsevier Ltd. All rights reserved.

Determinants, reproducibility, and seasonal variation of ergosterol levels in house dust.

Science.gov (United States)

Leppänen, H K; Nevalainen, A; Vepsäläinen, A; Roponen, M; Täubel, M; Laine, O; Rantakokko, P; von Mutius, E; Pekkanen, J; Hyvärinen, A

2014-06-01

This study aimed to clarify the determinants that affect the concentrations of ergosterol and viable fungi in house dust and to examine the seasonal variation and reproducibility of ergosterol concentrations indoors. In studying the determinants, dust samples from living room floors and vacuum cleaner dust bags were collected from 107 farming and 105 non-farming homes. Ergosterol levels were determined with gas chromatography-mass spectrometry,and the dust bag dust was cultivated for enumeration of fungal genera. Lifestyle and environmental factors, for example using of the fireplace, and visible mold observations in homes, explained 20–26% of the variation of fungal concentrations. For the reproducibility study, samples were collected from five urban homes in four different seasons. The reproducibility of ergosterol determinations within a sample was excellent (ICC = 89.8) for floor dust and moderate (ICC = 63.8) for dust bag dust, but poor when sampling the same home throughout a year (ICC = 31.3 and 12.6, respectively) due to large temporal variation in ergosterol concentrations. In conclusion, environmental characteristics only partially predicted the variation of fungal concentrations. Based on these studies, we recommend repeated sampling of dust over time if one seeks to adequately describe overall fungal levels and exposure in a home. This study shows that levels of ergosterol and viable fungi in house dust are related to visible mold observations. Only 20% of the variation in fungal levels can be explained with questionnaires, and therefore, environmental samples need to be taken in addition. Reproducibility of ergosterol determination was excellent for floor dust, and thus, ergosterol measurements from floor dust samples could be suitable for assessing the fungal load in building investigations. The temporal variation needs to be taken into account when describing the ergosterol concentration of urban homes.

Experimental Method for Measuring Dust Load on Surfaces in Rooms

DEFF Research Database (Denmark)

Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms, there is a n......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions....

Galactic dust and extinction

International Nuclear Information System (INIS)

Lyngaa, G.

1979-01-01

The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

Directory of Open Access Journals (Sweden)

Q. Wang

2018-03-01

Full Text Available Near-surface and vertical in situ measurements of atmospheric particles were conducted in Shanghai during 19–23 March 2010 to explore the transport and chemical evolution of dust particles in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one traveling over northern China (DS1 and the other passing over the coastal regions of eastern China (DS2. Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflected by the higher SO2 ∕ PM10 and NO2 ∕ PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42− and NO3− and the ratio of Ca2+ ∕ Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+] ∕ [SO42−+NO3−] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of particle optical properties in DS1 that dust dominantly accounted for ∼ 80–90 % of the total particle extinction from near the ground to ∼ 700 m. In contrast, the dust plumes in DS2 were restrained within lower altitudes while the extinction from spherical particles exhibited a maximum at a high altitude of ∼ 800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

Environmentally dependent dust chemistry of a super Asian dust storm in March 2010: observation and simulation

Science.gov (United States)

Wang, Qiongzhen; Dong, Xinyi; Fu, Joshua S.; Xu, Jian; Deng, Congrui; Jiang, Yilun; Fu, Qingyan; Lin, Yanfen; Huang, Kan; Zhuang, Guoshun

2018-03-01

Near-surface and vertical in situ measurements of atmospheric particles were conducted in Shanghai during 19-23 March 2010 to explore the transport and chemical evolution of dust particles in a super dust storm. An air quality model with optimized physical dust emission scheme and newly implemented dust chemistry was utilized to study the impact of dust chemistry on regional air quality. Two discontinuous dust periods were observed with one traveling over northern China (DS1) and the other passing over the coastal regions of eastern China (DS2). Stronger mixing extents between dust and anthropogenic emissions were found in DS2, reflected by the higher SO2 / PM10 and NO2 / PM10 ratios as well as typical pollution elemental species such as As, Cd, Pb, and Zn. As a result, the concentrations of SO42- and NO3- and the ratio of Ca2+ / Ca were more elevated in DS2 than in DS1 but opposite for the [NH4+] / [SO42-+NO3-] ratio, suggesting the heterogeneous reactions between calcites and acid gases were significantly promoted in DS2 due to the higher level of relative humidity and gaseous pollution precursors. Lidar observation showed a columnar effect on the vertical structure of particle optical properties in DS1 that dust dominantly accounted for ˜ 80-90 % of the total particle extinction from near the ground to ˜ 700 m. In contrast, the dust plumes in DS2 were restrained within lower altitudes while the extinction from spherical particles exhibited a maximum at a high altitude of ˜ 800 m. The model simulation reproduced relatively consistent results with observations that strong impacts of dust heterogeneous reactions on secondary aerosol formation occurred in areas where the anthropogenic emissions were intensive. Compared to the sulfate simulation, the nitrate formation on dust is suggested to be improved in the future modeling efforts.

Saharan dust levels in Greece and received inhalation doses

Directory of Open Access Journals (Sweden)

C. Mitsakou

2008-12-01

Full Text Available The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×10⁸ tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in the south European Region and especially in urban areas, where there is also significant contribution from anthropogenic sources. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM₁₀ concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM₁₀ concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by more than 20% to the annual number of exceedances – PM₁₀ values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

Energy Technology Data Exchange (ETDEWEB)

Vakylabad, Ali Behrad, E-mail: alibehzad86@yahoo.co.uk [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Engineers of Nano and Bio Advanced Sciences Company (ENBASCo.), ATIC, Mohaghegh University (Iran, Islamic Republic of); Schaffie, Mahin [Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ranjbar, Mohammad [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Manafi, Zahra [Sarcheshmeh Copper Complex, National Iranian Copper Industry Company (Iran, Islamic Republic of); Darezereshki, Esmaeel [Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Energy and Environmental Engineering Research Center (EERC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

2012-11-30

Highlights: Black-Right-Pointing-Pointer Flotation concentrate and smelter dust were sampled and combined. Black-Right-Pointing-Pointer Copper bioleaching from the combined was investigated. Black-Right-Pointing-Pointer Two bio-reactors were investigated and optimized: stirred and airlift. Black-Right-Pointing-Pointer STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu{sub 2}S, CuS, and Cu{sub 5}FeS{sub 4}.Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

International Nuclear Information System (INIS)

Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

2012-01-01

Highlights: ► Flotation concentrate and smelter dust were sampled and combined. ► Copper bioleaching from the combined was investigated. ► Two bio-reactors were investigated and optimized: stirred and airlift. ► STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu 2 S, CuS, and Cu 5 FeS 4 .Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Characteristics of mineral dust impacting the Persian Gulf

Science.gov (United States)

Ahmady-Birgani, Hesam; McQueen, Kenneth G.; Mirnejad, Hassan

2018-02-01

It is generally assumed that severe dust events in western Iran could be responsible for elevated levels of toxic and radioactive elements in the region. Over a period of 5 months, from January 2012 to May 2012, dust particles in the size range PM10 (i.e. chemical compositions of dust and aerosol samples collected during the non-dusty periods and during two severe dust events. Results of ICP-MS analysis of components indicate that during dust events the concentrations of major elements such as Ca, Mg, Al and K increase relative to ambient conditions when Fe and trace elements such as Cu, Cr, Ni, Pb and Zn are in higher proportions. Toxic trace elements that are generally ascribed to human activities, including industrial and urban pollution, are thus proportionately more abundant in the dust under calm conditions than during dust events, when their concentration is diluted by more abundant mineral particles of quartz, calcite and clay. The variability of chemical species during two dust events, noted by tracking the dust plumes in satellite images, was also assessed and the results relate to two different source areas, namely northern Iraq and northwestern Syria.

Interannual Variability in Dust Deposition, Radiative Forcing, and Snowmelt Rates in the Colorado River Basin

Science.gov (United States)

Skiles, M.; Painter, T. H.; Deems, J. S.; Barrett, A. P.

2011-12-01

.043 mg/g higher dust concentration at the subalpine site. The smaller magnitude of difference at GMSP, 0.61 mg/g higher concentration in 2010, indicates that there is variability in dust sources and loading between study plots. Observations from both sites indicate that dust concentrations are not correlated with total number of dust events and that dust loading and concentrations are highly variable. The interannual and study plot variation helps broaden our understanding of the dynamics and implications of dust in snow in the Colorado River Basin.

The theory and technology of enclosure dust-laying model in speeded advance of coal road

Energy Technology Data Exchange (ETDEWEB)

Wei-Min Cheng; Xiang-Sheng Liu; Guo-Qiang Ruan; Yun-Xiang Guo; Gang Wang [Shandong University of Science and Technology, Qingdao (China). Key Laboratory of Mine Disaster Prevention and Control

2009-02-15

In order to solve the problem of high dust concentration caused by the rapid advance of coal roadways using the ABM20 development machine, a method suitable for the rapid advance of coal roadways in China was proposed. By using the mathematic model method to contrast the wind current field and dust field of the drivage face under different drivage velocities, an optimized drivage velocity of the fully-mechanized development machine was obtained. The theories were tested in an industry experiment. Analysis of the data indicates that the proposed enclosure dust-laying system can significantly lower the dust concentration at the heading face. It also has some advantages in accomplishing the effective advance of coal mines. 9 refs., 5 figs.

Foehn-induced effects on dust pollution, frontal clouds and solar radiation in the Dead Sea valley

Science.gov (United States)

Kishcha, Pavel; Starobinets, Boris; Alpert, Pinhas; Kaplan, Michael

2017-04-01

The significant drying up of the Dead Sea over the past 40 years has led to an increase in an exposed area contributing to local dust pollution. Measurements show that, sometimes, in the Dead Sea valley, dust pollution can reach extreme concentrations up to several thousands of micrograms per cubic meters. Our analysis of a meteorological situation shows that a foehn phenomenon can be a causal factor for the aforementioned extreme local dust concentration. This foehn phenomenon creates strong warm and dry winds, which are accompanied by air turbulence and temperature inversion. In our study, foehn-induced effects on dust pollution, frontal clouds and solar radiation were analyzed over the Judean Mountains ( 1000 m) and over the Dead Sea valley (-420 m), using high-resolution numerical simulations and in-situ observations at meteorological stations located across the mountain ridge. An extreme dust episode occurring on March 22, 2013, was analyzed, which was characterized by measured surface dust concentrations of up to 7000 µg m-3 in the Dead Sea valley. We simulated this foehn phenomenon with the 3-km resolution COSMO-ART model. Our analysis has shown that the foehn phenomenon could be observed even over the relatively low Judean Mountains. This analysis was based on various meteorological, pyranometer, radar, and aerosol measurements together with high-resolution model data. In the Dead Sea valley, the maximum aerosol optical depth (AOD) did not coincide with the maximum surface dust concentration. This lack of coincidence indicates difficulties in using satellite-based AOD for initializing dust concentration within numerical forecast systems over this region with complex terrain. In the western Dead Sea valley, strong foehn winds of over 20 m/s were accompanied by maximal air turbulence leading to maximal local dust emissions. Thus, the model showed that, by creating significant turbulence, the foehn phenomenon intensified the saltation (bombardment) mechanism

Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

Science.gov (United States)

Mamali, Dimitra; Marinou, Eleni; Sciare, Jean; Pikridas, Michael; Kokkalis, Panagiotis; Kottas, Michael; Binietoglou, Ioannis; Tsekeri, Alexandra; Keleshis, Christos; Engelmann, Ronny; Baars, Holger; Ansmann, Albert; Amiridis, Vassilis; Russchenberg, Herman; Biskos, George

2018-05-01

In situ measurements using unmanned aerial vehicles (UAVs) and remote sensing observations can independently provide dense vertically resolved measurements of atmospheric aerosols, information which is strongly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse mode (i.e. particles having radii > 0.5 µm), where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.

Wood Dust

Science.gov (United States)

Learn about wood dust, which can raise the risk of cancers of the paranasal sinuses and nasal cavity. High amounts of wood dust are produced in sawmills, and in the furniture-making, cabinet-making, and carpentry industries.

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

Science.gov (United States)

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

2010-01-01

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

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

Science.gov (United States)

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

2015-08-01

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

Investigating A Novel Flame Retardant Known as V6: Measurements in Baby Products, House Dust and Car Dust

Science.gov (United States)

Fang, Mingliang; Webster, Thomas F.; Gooden, David; Cooper, Ellen M.; McClean, Michael D.; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M.

2013-01-01

With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors’ knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected, and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (> 98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using Accelerated Solvent Extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6 % of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than the house dust, potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and TCEP in the dust samples, suggesting that the use of V6 is a significant source of TCEP

Air Pollution Modelling to Predict Maximum Ground Level Concentration for Dust from a Palm Oil Mill Stack

Directory of Open Access Journals (Sweden)

Regina A. A.

2010-12-01

Full Text Available The study is to model emission from a stack to estimate ground level concentration from a palm oil mill. The case study is a mill located in Kuala Langat, Selangor. Emission source is from boilers stacks. The exercise determines the estimate the ground level concentrations for dust to the surrounding areas through the utilization of modelling software. The surround area is relatively flat, an industrial area surrounded by factories and with palm oil plantations in the outskirts. The model utilized in the study was to gauge the worst-case scenario. Ambient air concentrations were garnered calculate the increase to localized conditions. Keywords: emission, modelling, palm oil mill, particulate, POME

Concentration of the genera Aspergillus, Eurotium and Penicillium in 63-μm house dust fraction as a method to predict hidden moisture damage in homes

Directory of Open Access Journals (Sweden)

Assadian Ojan

2009-07-01

Full Text Available Abstract Background Quantitative measurements of mould enrichment of indoor air or house dust might be suitable surrogates to evaluate present but hidden moisture damage. Our intent was to develop a house-dust monitoring method to detect hidden moisture damage excluding the influence of outdoor air, accumulated old dust, and dust swirled up from room surfaces. Methods Based on standardized measurement of mould spores in the 63-μm fraction of house dust yielded by carpets, the background concentrations were determined and compared to simultaneously obtained colony numbers and total spore numbers of the indoor air in 80 non-mouldy living areas during summer and winter periods. Additionally, sampling with a vacuum-cleaner or manual sieve was compared to sampling with a filter holder or sieving machine, and the evaluative power of an established two-step assessment model (lower and upper limits was compared to that of a one-step model (one limit in order to derive concentration limits for mould load in house dust. Results Comparison with existing evaluation procedures proved the developed method to be the most reliable means of evaluating hidden moisture damage, yielding the lowest false-positive results (specificity 98.7%. Background measurements and measurements in 14 mouldy rooms show that even by evaluating just the indicator genera in summer and winter, a relatively certain assessment of mould infestation is possible. Conclusion A one-step evaluation is finally possible for house dust. The house-dust evaluation method is based on analysis of the indicator genera Aspergillus, Eurotium and Penicillium spp., which depend on the total fungal count. Inclusion of further moisture indicators currently appears questionable, because of outdoor air influence and the paucity of measurements.

Change in dust collection efficiency of liquid collectors in conditions of dedusting liquid recirculation

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Krawczyk Janusz

2017-12-01

Full Text Available The high efficiency of industrial wet scrubbers is the result of a simultaneous formation of dust particle collectors. Collectors can be understood as droplets of atomised liquid, bubbles formed in the conditions of intensive barbotage, liquid surface and wet surfaces. All collectors are formed during the operation of a circulating unit. The efficiency of dust collection process also depends on the ability of dust particles to be absorbed by collectors. The study provides an experimental analysis of the effect of the increasing concentration of a dust collection liquid in the conditions of full liquid recirculation on the efficiency of dust collection process in the examined types of collectors.

Ground level and Lidar monitoring of volcanic dust and dust from Patagonia

Science.gov (United States)

Otero, L. A.; Losno, R.; Salvador, J. O.; Journet, E.; Qu, Z.; Triquet, S.; Monna, F.; Balkanski, Y.; Bulnes, D.; Ristori, P. R.; Quel, E. J.

2013-05-01

A combined approach including ground level aerosol sampling, lidar and sunphotometer measurements is used to monitor suspended particles in the atmosphere at several sites in Patagonia. Motivated by the Puyehue volcanic eruption in June 2011 two aerosol monitoring stations with several passive and active instruments were installed in Bariloche and Comodoro Rivadavia. The main goal which is to monitor ground lifted and transported ashes and dust involving danger to civil aviation, is achieved by measuring continuously aerosol concentration at ground level and aerosol vertical distribution using lidar. In addition, starting from December 2011, continuous series of weekly accumulated aerosol concentrations at Rio Gallegos are being measured to study the impact of Patagonian dust over the open ocean on phytoplankton primary productivity and CO2 removal. These measurements are going to be coupled with LIDAR monitoring and a dust optical response models to test if aerosol extrapolation can be done from the ground to the top of the layer. Laboratory chemical analysis of the aerosols will include elemental composition, solubilisation kinetic and mineralogical determination. Expected deliverables for this study is the estimation of the amount of dust exported from Patagonia towards the South Atlantic, its chemical properties, including bioavailability simulation, from model and comparison to experimental measurements.

'Nuisance Dust' - a Case for Recalibration?

Science.gov (United States)

Datson, Hugh; Marker, Brian

2013-04-01

This paper considers the case for a review and recalibration of limit values and acceptability criteria for 'nuisance dust', a widely encountered but poorly defined and regulated aspect of particulate matter pollution. Specific dust fractions such as PM10 and asbestiforms are well characterised and have limit values enshrined in legislation. National, and international, limit values for acceptable concentrations of PM10 and other fractions of particulate matter have been defined and agreed. In the United Kingdom (UK), these apply to both public and workplace exposures. By contrast, there is no standard definition or universal criteria against which acceptable levels for 'nuisance dust' can be assessed. This has implications for land-use planning and resource utilisation. Without meaningful limit values, inappropriate development might take place too near to residential dwellings or land containing economically important mineral resources may be effectively sterilised. Furthermore, the expression 'nuisance dust' is unhelpful in that 'nuisance' has a specific meaning in environmental law whilst 'nuisance dust' is often taken to mean 'generally visible particulate matter'. As such, it is associated with the social and broader environmental impacts of particulate matter. PM10 concentrations are usually expressed as a mass concentration over time. These can be determined using a range of techniques. While results from different instruments are generally comparable, data obtained from alternative methods for measuring 'nuisance dust' are rarely interchangeable. In the UK, many of the methods typically used are derived from approaches developed under the HMIP (Her Majesty's Inspectorate of Pollution) regime in the 1960s onwards. Typical methods for 'nuisance dust' sampling focus on measurement of dust mass (from the weight of dust collected in an open container over time) or dust soiling (from loss of reflectance and or obscuration of a surface discoloured by dust over

Operational aerosol and dust storm forecasting

International Nuclear Information System (INIS)

Westphal, D L; Curtis, C A; Liu, M; Walker, A L

2009-01-01

The U. S. Navy now conducts operational forecasting of aerosols and dust storms on global and regional scales. The Navy Aerosol Analysis and Prediction System (NAAPS) is run four times per day and produces 6-day forecasts of sulfate, smoke, dust and sea salt aerosol concentrations and visibility for the entire globe. The Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS (registered) ) is run twice daily for Southwest Asia and produces 3-day forecasts of dust, smoke, and visibility. The graphical output from these models is available on the Internet (www.nrlmry.navy.mil/aerosol/). The aerosol optical properties are calculated for each specie for each forecast output time and used for sea surface temperature (SST) retrieval corrections, regional electro-optical (EO) propagation assessments, and the development of satellite algorithms. NAAPS daily aerosol optical depth (AOD) values are compared with the Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) AOD values. Visibility forecasts are compared quantitatively with surface synoptic reports.

Airborne fungal and bacterial components in PM1 dust from biofuel plants.

Science.gov (United States)

Madsen, Anne Mette; Schlünssen, Vivi; Olsen, Tina; Sigsgaard, Torben; Avci, Hediye

2009-10-01

Fungi grown in pure cultures produce DNA- or RNA-containing particles smaller than spore size ( 3)-beta-D-glucans. In the 29 PM(1) samples, cultivable fungi were found in six samples and with a median concentration below detection level. Using microscopy, fungal spores were identified in 22 samples. The components NAGase and (1 --> 3)-beta-D-glucans, which are mainly associated with fungi, were present in all PM(1) samples. Thermophilic actinomycetes were present in 23 of the 29 PM(1) samples [average = 739 colony-forming units (CFU) m(-3)]. Cultivable and 'total bacteria' were found in average concentrations of, respectively, 249 CFU m(-3) and 1.8 x 10(5) m(-3). DNA- and RNA-containing particles of different lengths were counted by microscopy and revealed a high concentration of particles with a length of 0.5-1.5 microm and only few particles >1.5 microm. The number of cultivable fungi and beta-glucan in the total dust correlated significantly with the number of DNA/RNA-containing particles with lengths of between 1.0 and 1.5 microm, with DNA/RNA-containing particles >1.5 microm, and with other fungal components in PM(1) dust. Airborne beta-glucan and NAGase were found in PM(1) samples where no cultivable fungi were present, and beta-glucan and NAGase were found in higher concentrations per fungal spore in PM(1) dust than in total dust. This indicates that fungal particles smaller than fungal spore size are present in the air at the plants. Furthermore, many bacteria, including actinomycetes, were present in PM(1) dust. Only 0.2% of the bacteria in PM(1) dust were cultivable.

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

Science.gov (United States)

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

2017-07-01

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

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

Science.gov (United States)

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

2008-12-01

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

Atmospheric response to Saharan dust deduced from ECMWF reanalysis increments

Science.gov (United States)

Kishcha, P.; Alpert, P.; Barkan, J.; Kirchner, I.; Machenhauer, B.

2003-04-01

This study focuses on the atmospheric temperature response to dust deduced from a new source of data - the European Reanalysis (ERA) increments. These increments are the systematic errors of global climate models, generated in reanalysis procedure. The model errors result not only from the lack of desert dust but also from a complex combination of many kinds of model errors. Over the Sahara desert the dust radiative effect is believed to be a predominant model defect which should significantly affect the increments. This dust effect was examined by considering correlation between the increments and remotely-sensed dust. Comparisons were made between April temporal variations of the ERA analysis increments and the variations of the Total Ozone Mapping Spectrometer aerosol index (AI) between 1979 and 1993. The distinctive structure was identified in the distribution of correlation composed of three nested areas with high positive correlation (> 0.5), low correlation, and high negative correlation (Forecast(ECMWF) suggests that the PCA (NCA) corresponds mainly to anticyclonic (cyclonic) flow, negative (positive) vorticity, and downward (upward) airflow. These facts indicate an interaction between dust-forced heating /cooling and atmospheric circulation. The April correlation results are supported by the analysis of vertical distribution of dust concentration, derived from the 24-hour dust prediction system at Tel Aviv University (website: http://earth.nasa.proj.ac.il/dust/current/). For other months the analysis is more complicated because of the essential increasing of humidity along with the northward progress of the ITCZ and the significant impact on the increments.

Radioisotope dust pollution monitor

International Nuclear Information System (INIS)

Szepke, R.; Harasimczuk, J.; Dobrowiecki, J.

1990-01-01

Measuring principles and specification of two dust monitors: station-type AMIZ and portable-type PIK-10 for ambient air pollution are presented. The first one, a fully automatic instrument is destined for permanent monitoring of air pollution in preset sampling time from .25 to 24 hours. The second one was developed as a portable working model. Both instruments display their results in digital form in dust concentration units. (author)

Household vacuum cleaners vs. the high-volume surface sampler for collection of carpet dust samples in epidemiologic studies of children

Directory of Open Access Journals (Sweden)

Buffler Patricia A

2008-02-01

Full Text Available Abstract Background Levels of pesticides and other compounds in carpet dust can be useful indicators of exposure in epidemiologic studies, particularly for young children who are in frequent contact with carpets. The high-volume surface sampler (HVS3 is often used to collect dust samples in the room in which the child had spent the most time. This method can be expensive and cumbersome, and it has been suggested that an easier method would be to remove dust that had already been collected with the household vacuum cleaner. However, the household vacuum integrates exposures over multiple rooms, some of which are not relevant to the child's exposure, and differences in vacuuming equipment and practices could affect the chemical concentration data. Here, we compare levels of pesticides and other compounds in dust from household vacuums to that collected using the HVS3. Methods Both methods were used in 45 homes in California. HVS3 samples were collected in one room, while the household vacuum had typically been used throughout the home. The samples were analyzed for 64 organic compounds, including pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls (PCBs, using GC/MS in multiple ion monitoring mode; and for nine metals using conventional microwave-assisted acid digestion combined with ICP/MS. Results The methods agreed in detecting the presence of the compounds 77% to 100% of the time (median 95%. For compounds with less than 100% agreement, neither method was consistently more sensitive than the other. Median concentrations were similar for most analytes, and Spearman correlation coefficients were 0.60 or higher except for allethrin (0.15 and malathion (0.24, which were detected infrequently, and benzo(kfluoranthene (0.55, benzo(apyrene (0.55, PCB 105 (0.54, PCB 118 (0.54, and PCB 138 (0.58. Assuming that the HVS3 method is the "gold standard," the extent to which the household vacuum cleaner method yields relative risk

Aerosol-ozone correlations during dust transport episodes

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P. Bonasoni

2004-01-01

Full Text Available Its location in the Mediterranean region and its physical characteristics render Mt. Cimone (44°11′ N, 10°42′ E, the highest peak of the Italian northern Apennines (2165 m asl, particularly suitable to study the transport of air masses from the north African desert area to Europe. During these northward transports 12 dust events were registered in measurements of the aerosol concentration at the station during the period June–December 2000, allowing the study of the impact of mineral dust transports on free tropospheric ozone concentrations, which were also measured at Mt. Cimone. Three-dimensional backward trajectories were used to determine the air mass origin, while TOMS Aerosol Index data for the Mt. Cimone area were used to confirm the presence of absorbing aerosol over the measurement site. A trajectory statistical analysis allowed identifying the main source areas of ozone and aerosols. The analysis of these back trajectories showed that central Europe and north and central Italy are the major pollution source areas for ozone and fine aerosol, whereas the north African desert regions were the most important source areas for coarse aerosol and low ozone concentrations. During dust events, the Mt. Cimone mean volume concentration for coarse particles was 6.18 µm3/cm3 compared to 0.63 µm3/cm3 in dust-free conditions, while the ozone concentrations were 4% to 21% lower than the monthly mean background values. Our observations show that surface ozone concentrations were lower than the background values in air masses coming from north Africa, and when these air masses were also rich in coarse particles, the lowest ozone values were registered. Moreover, preliminary results on the possible impact of the dust events on PM10 and ozone values measured in Italian urban and rural areas showed that during the greater number of the considered dust events, significant PM10 increases and ozone decreases have occurred in the Po valley.

1500-year Record of trans-Pacific Dust Flux collected from the Denali Ice Core, Mt. Hunter, Alaska

Science.gov (United States)

Saylor, P. L.; Osterberg, E. C.; Koffman, B. G.; Winski, D.; Ferris, D. G.; Kreutz, K. J.; Wake, C. P.; Handley, M.; Campbell, S. W.

2016-12-01

Mineral dust aerosols are a critical component of the climate system through their influence on atmospheric radiative forcing, ocean productivity, and surface albedo. Dust aerosols derived from Asian deserts are known to reach as far as Europe through efficient transport in the upper tropospheric westerlies. While centennially-to-millennially resolved Asian dust records exist over the late Holocene from North Pacific marine sediment cores and Asian loess deposits, a high-resolution (sub-annual to decadal) record of trans-Pacific dust flux will significantly improve our understanding of North Pacific dust-climate interactions and provide paleoclimatological context for 20th century dust activity. Here we present an annually resolved 1500-year record of trans-Pacific dust transport based on chemical and physical dust measurements in parallel Alaskan ice cores (208 m to bedrock) collected from the summit plateau of Mt. Hunter in Denali National Park. The cores were sampled at high resolution using a continuous melter system with discrete analyses for major ions (Dionex ion chromatograph), trace elements (Element2 inductively coupled plasma mass spectrometer), and stable water isotope ratios (Picarro laser ringdown spectroscopy), and continuous flow analysis for dust concentration and size distribution (Klotz Abakus). We compare the ice core dust record to instrumental aerosol stations, satellite observations, and dust model data from the instrumental period, and evaluate climatic controls on dust emission and trans-Pacific transport using climate reanalysis data, to inform dust-climate relationships over the past 1500 years. Physical particulate and chemical data demonstrate remarkable fidelity at sub-annual resolution, with both displaying a strong springtime peak consistent with periods of high dust activity over Asian desert source regions. Preliminary results suggest volumetric mode typically ranges from 4.5 - 6.5 um, with a mean value of 5.5 um. Preliminary

[The epidemiological validation of the MPEL for grain dust in the atmosphere].

Science.gov (United States)

Pinigin, M A; Cherepov, E M; Safiulin, A A; Petrova, I V; Mukhambetova, L Kh; Osipova, E M; Veselov, A P

1998-01-01

The use of calculating and gravimetric methods for examining the grain dust pollution of the ambient air at the site of an elevator determined the maximum single, mean daily, and mean annual concentrations at different distances from the source of dust emission. The mean ratio of these concentrations was 12.1:4.3:1, respectively. The calculated concentration-effect and concentration-time relationships provided evidence for the maximum single, mean daily, and mean annual allowable concentrations for grain dust in the ambient air.

Stability evaluation of house dust mite vaccines for sublingual immunotherapy

Directory of Open Access Journals (Sweden)

MARIJA GAVROVIĆ-JANKULOVIĆ

2010-01-01

Full Text Available Allergen-specific immunotherapy with house dust mite (HDM allergen extracts can effectively alleviate the symptoms of allergic rhinitis and asthma. The efficacy of the immunotherapeutic treatment is highly dependent on the quality of house dust mite vaccines. This study was performed to assess the stability of house dust mite allergen vaccines prepared for sublingual immunotherapy. Lyophilized Dermatophagoides pteronyssinus (Dpt mite bodies were the starting material for the production of sublingual vaccines in four therapeutic concentrations. The stability of the extract for vaccine production, which was stored below 4 °C for one month, showed consistence in the protein profile in SDS PAGE. ELISA-inhibition showed that the potencies of Dpt vaccines during a 12 month period were to 65–80 % preserved at all analyzed therapeutic concentrations. This study showed that glycerinated Dpt vaccines stored at 4 °C preserved their IgE-binding potential during a 12 month period, implying their suitability for sublingual immunotherapeutic treatment of HDM allergy.

Study on an intense dust storm over Greece

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Kaskaoutis, D. G.; Kambezidis, H. D.; Nastos, P. T.; Kosmopoulos, P. G.

Springtime constitutes the most favorable period for Sahara dust outbreaks and transport over Eastern Mediterranean. This study investigates the aerosol properties during April 2005 using remote-sensing and ground-based measurements. Three dust events with high aerosol optical depth (AOD) values have been observed during the measuring period, with duration of two days, i.e. 11-12, 16-17 and 25-26 April 2005. In this paper we mainly focus on the intense dust event of 16-17 April 2005, when a thick dust layer transported from Libya affected the whole Greek territory. Very high AOD values obtained from Aqua-MODIS sensor were observed over Greece (mean 2.42 ± 1.25) on 17 April, while the respective mean April value was 0.31 ± 0.09. The AOD at 550 nm (AOD 550) values over Crete were even larger, reaching ˜4.0. As a consequence, the PM 10 concentrations over Athens dramatically increased reaching up to 200 μg m -3. On the other hand, the fine-mode fraction values obtained from Terra-MODIS showed a substantial decrease in the whole Greek area on 17 April with values below 0.2 in the Southern regions. The intense dust layer showed a complex behavior concerning its spatial and temporal evolution and allowed us to study the changes in the optical properties of the desert dust particles along their transport routes due to the mixing processes with other aerosol types. The results from different measurements (ground-based and remote-sensing) did not contradict each other and, therefore, are adequate for monitoring of dust load over the Eastern Mediterranean.

Occurrence of polybrominated diphenyl ethers in floor and elevated surface house dust from Shanghai, China.

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Niu, Dong; Qiu, Yanling; Li, Li; Zhou, Yihui; Du, Xinyu; Zhu, Zhiliang; Chen, Ling; Lin, Zhifen

2018-04-24

House dust is the main source of human exposure to flame retardants by ingestion. This study investigated the occurrence of polybrominated diphenyl ethers (PBDEs) in indoor dust from 22 houses in Shanghai, China. House dust was separately collected from the floor and elevated furnishings surface (mostly between 0.5 and 2 m height) for comparison. The concentrations of ∑ 22 PBDEs ranged from 19.4 to 3280 ng/g (with a geometric mean of 203 ng/g) and from 55.1 to 792 ng/g (with a geometric mean of 166 ng/g) in floor dust (FD) and elevated surface dust (ESD), respectively. BDE-209 was the predominant congener, accounting for about 73.1% of total PBDE burdens. In terms of congener profiles, the comparison of FD and ESD revealed no significant differences except for the ratio of BDE-47/BDE-99. ESD samples displayed a ratio of BDE-47/BDE-99 very similar to commercial penta-BDE products DE-71 while the ratio in FD was exceptionally higher. Significant correlation was found between concentrations of commercial penta-BDE compositions in FD and ESD (p house dust exhibited temporal stability. Human exposure to PBDEs via dust ingestion was estimated. The highest daily intake of PBDEs was for toddlers by using 95th percentile concentrations of PBDEs via high dust ingestion in FD (23.07 ng/kg bw/day). About 20-fold difference in exposure estimates between toddlers and adults supports that toddlers are facing greater risk from indoor floor dust. Expectedly, this study highlighted the point that residents in Shanghai were exposed to low doses of PBDEs in house dust.

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

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

2013-08-01

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

Saharan Dust Event Impacts on Cloud Formation and Radiation over Western Europe

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Bangert, M.; Nenes, A.; Vogel, B.; Vogel, H.; Barahona, D.; Karydis, V. A.; Kumar, P.; Kottmeier, C.; Blahak, U.

2013-01-01

We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle-microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties. The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l-1 during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds. Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected). This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to -75Wm-2. Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80Wm-2, and the incoming long-wave radiation at the surface was increased significantly in the order of +10Wm-2. The strong radiative forcings associated with dust caused a reduction in surface temperature in the order of -0

Lung cancer and inhaled uranium ore dust in rats

International Nuclear Information System (INIS)

Mitchel, R.E.J.; Jackson, J.S.

1997-01-01

Using a nose only inhalation system, 187 nine week old male Sprague-Dawley rats were exposed to two different concentrations of natural uranium ore dust aerosol (44% U) without significant radon content. Inhalation exposures averaged about 4.2 h/day, 5 days/week for 65 weeks at which point lung uranium burdens in the two groups averaged 0.9 and 1.9 mg/g dry weight. Animals (63) exposed to the air stream without dust served as controls. After inhalation exposure ceased, the rats were allowed to live for their natural lifetime, a maximum of about 900 days after the start of dust inhalation. Lung uranium burdens were measured at the time of death of each animal. Lung burdens were found to decline exponentially after dust inhalation ceased, and the rate of decline was independent of the initial lung burden. All lungs were examined at necropsy and histologically for lung tumors. Lung tumors of lung origin were observed in both exposed groups and in the control group. The frequency of primary malignant lung tumors was 0.016, 0.175 and 0.328 and primary non-malignant lung tumors 0.016, 0.135 and 0.131 in the control low and high aerosol exposed groups respectively. Absorbed dose to the lung was calculated for each animal in the study. The average maximum doses for all the animals exposed to the low or high concentration of dust aerosol were 0.87 Gy and 1.64 Gy respectively. The average risk of malignant lung tumors from inhaled natural uranium ore dust was therefore about 0.20 tumors/animal/Gy. For animals with lung tumors, the average doses were 0.98 and 1.90 in the exposed groups. In both exposed groups, the frequency of primary malignant or non-malignant lung tumors was significantly greater than in the control group (p < 0.02) and the frequency of primary malignant lung tumors in the two exposed group were significantly different from each other (p = 0.05). The frequency of primary lung tumors (malignant and non-malignant) was calculated as a function of dose

Dust in High-Redshift Galaxies

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

1997-03-01

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

Simulation and analysis of synoptic scale dust storms over the Arabian Peninsula

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Beegum, S. Naseema; Gherboudj, Imen; Chaouch, Naira; Temimi, Marouane; Ghedira, Hosni

2018-01-01

Dust storms are among the most severe environmental problems in arid and semi-arid regions of the world. The predictability of seven dust events, viz. D1: April 2-4, 2014; D2: February 23-24, 2015; D3: April 1-3, 2015; D4: March 26-28, 2016; D5: August 3-5, 2016; D6: March 13-14, 2017 and D7:March 19-21, 2017, are investigated over the Arabian Peninsula using a regionally adapted chemistry transport model CHIMERE coupled with the Weather Research and Forecast (WRF) model. The hourly forecast products of particulate matter concentrations (PM10) and aerosol optical depths (AOD) are compared against both satellite-based (MSG/SEVRI RGB dust, MODIS Deep Blue Aerosol Optical Depth: DB-AOD, Ozone Monitoring Instrument observed UV Aerosol Absorption Index: OMI-AI) and ground-based (AERONET AOD) remote sensing products. The spatial pattern and the time series of the simulations show good agreement with the observations in terms of the dust intensity as well as the spatiotemporal distribution. The causative mechanisms of these dust events are identified by the concurrent analyses of the meteorological data. From these seven storms, five are associated with synoptic scale meteorological processes, such as prefrontal storms (D1 and D7), postfrontal storms of short (D2), and long (D3) duration types, and a summer shamal storm (D6). However, the storms D4 and D6 are partly associated with mesoscale convective type dust episodes known as haboobs. The socio-economic impacts of the dust events have been assessed by estimating the horizontal visibility, air quality index (AQI), and the dust deposition flux (DDF) from the forecasted dust concentrations. During the extreme dust events, the horizontal visibility drops to near-zero values co-occurred withhazardous levels of AQI and extremely high dust deposition flux (250 μg cm- 2 day- 1).

Simulation of the dust suppression process with foam in the areas of belt conveyors

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Bespalov Vadim

2017-01-01

Full Text Available The article provides the analysis of the physical essence and simulation of the process of dust retention with foam in the air of working zones of belt conveyors transporting sand, crushed stone, gravel, coal, grain. In accordance with the proposed physical-energy concept of simulation of the process of dust control its physical essence is in a deliberate sequential action on the dust particles with previously prepared by the parameters external (additional dispersed systems. Use of dust retention technology foam method provides high efficiency of reducing the concentration of dust in the air of working areas of belt conveyors, which varies in the range of 85.0–99.0 %, which provides the standard level of dust contamination (MPC in air of working areas of listed industrial sources of formation and emission of dust.

Investigating a novel flame retardant known as V6: measurements in baby products, house dust, and car dust.

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Fang, Mingliang; Webster, Thomas F; Gooden, David; Cooper, Ellen M; McClean, Michael D; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M

2013-05-07

With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors' knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this, a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (>98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using accelerated solvent extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3 mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6% of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from <5 ng/g to 1110 ng/g with a median of 12.5 ng/g, and <5 ng/g to 6160 ng/g in the car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than in the house dust potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and TCEP in

Investigation of Three-Dimensional Evolution of East Asian Dust Storm by Modeling and Remote Sensing Measurements

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Jiawei Li

2015-01-01

Full Text Available The three-dimensional evolution of an East Asian dust storm during 23–26 April 2009 was investigated by utilizing a regional air quality model system (RAQMS and satellite measurements. This severe dust storm hit Mt. Tai in east China with daily mean PM10 concentration reaching 1400 μg/m3 and the model captured the PM10 variation reasonably well. Modeled spatial distributions of AOD and vertical profiles of aerosol extinction coefficient during the dust storm were compared with MODIS and CALIPSO data, demonstrating that RAQMS was able to reproduce the 3D structure and the evolution of the dust storm reasonably well. During early days of the dust storm, daily mean dust-induced AOD exceeded 2.0 over dust source regions (the Gobi desert and the Taklamakan desert and was in a range of 1.2–1.8 over the North China Plain, accounting for about 98% and up to 90% of total AOD over corresponding areas, respectively. The top of the dust storm reached about 8 km over east China, with high dust concentration locating at around 40°N. Dust aerosol below 2 km was transported southeastward off the Gobi desert while dust above 2 km was transported out of China along 40°–45°N.

Identification of Dust and Ice Cloud Formation from A-Train Datasets

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Russell, D. S.; Liou, K. N.

2014-12-01

Dust aerosols are effective ice nuclei for clouds and instances of nucleation have been well studied in laboratory experiments. We used CALIOP/CALIPSO, MODIS/Aqua, and CloudSat on the A-Train to find collocated instances of clouds characterized as water by MODIS, but contain ice water as indicated by CloudSat. The vertical profiles of CALIPSO detect the presence of dust and polluted dust near clouds. This study concentrates on high dust aerosol areas including the regions surrounding the Sahara Desert as well as South Asia including the Tibetan Plateau. These cases display the effects of dust acting as ice nuclei in the time frame between MODIS overpass and CloudSat overpass (~45 seconds). Utilizing available datasets, we then carried out radiative transfer calculations to understand spectral radiative forcing differences between water and ice clouds, particularly over snow surfaces at the Tibetan Plateau.

Dust grain dynamics due to nonuniform and nonstationary high-frequency radiations in cold magnetoplasmas

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A. K. Nekrasov

2006-03-01

Full Text Available A general nonlinear theory for low-frequency electromagnetic field generation due to high-frequency nonuniform and nonstationary electromagnetic radiations in cold, uniform, multicomponent, dusty magnetoplasmas is developed. This theory permits us to consider the nonlinear action of all waves that can exist in such plasmas. The equations are derived for the dust grain velocities in the low-frequency nonlinear electric fields arising due to the presence of electromagnetic cyclotron waves travelling along the background magnetic field. The dust grains are considered to be magnetized as well as unmagnetized. Different regimes for the dust particle dynamics, depending on the spatio-temporal change of the wave amplitudes and plasma parameters, are discussed. It is shown that induced nonlinear electric fields can have both an electrostatic and electromagnetic nature. Conditions for maximum dust acceleration are found. The results obtained may be useful for understanding the possible mechanisms of dust grain dynamics in astrophysical, cosmic and laboratory plasmas under the action of nonuniform and nonstationary electromagnetic waves.

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

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

2018-01-19

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

Organophosphate Flame Retardants in House Dust from South China and Related Human Exposure Risks.

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Tan, Hongli; Peng, Changfeng; Guo, Ying; Wang, Xiaodong; Wu, Yan; Chen, Da

2017-09-01

House dust associated with organic pollutants is not only a potential source of pollutants to the outdoor environment, but also a source to human exposure. The present study investigated the occurrence and concentrations of organophosphate flame retardants (OPFRs) in house dust collected from South China dwellings (n = 20). The results revealed a universal presence of most target OPFRs in house dust, with concentrations of ΣOPFRs ranging from 2.06 to 19.95 μg/g. The median concentration of ΣOPFR (9.20 μg/g) was one order of magnitude greater than that of polybrominated diphenyl ethers (0.80 μg/g). The composition of OPFR chemicals in house dust was dominated by chlorinated OPFRs, such as tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(1-chloro-2-propyl) phosphate (TCPP). This compositional pattern was different from what has been reported in indoor dust from many other countries, where tris(2-butoxyethyl) phosphate (TBEP) was generally dominant. The daily intake of OPFRs by adults was estimated to be 1.6 and 4.2 ng/kg body weight/day under average and high exposure scenarios, respectively, and 31.7 and 127 ng/kg body weight/day for toddlers.

Computational algorithm for molybdenite concentrate annealing

International Nuclear Information System (INIS)

Alkatseva, V.M.

1995-01-01

Computational algorithm is presented for annealing of molybdenite concentrate with granulated return dust and that of granulated molybdenite concentrate. The algorithm differs from the known analogies for sulphide raw material annealing by including the calculation of return dust mass in stationary annealing; the latter quantity varies form the return dust mass value obtained in the first iteration step. Masses of solid products are determined by distribution of concentrate annealing products, including return dust and benthonite. The algorithm is applied to computations for annealing of other sulphide materials. 3 refs

Lithium Wall Conditioning And Surface Dust Detection On NSTX

International Nuclear Information System (INIS)

Skinner, C.H.; Allain, J.P.; Bell, M.G.; Friesen, F.Q.L.; Heim, B.; Jaworski, M.A.; Kugel, H.; Maingi, R.; Rais, B.; Taylor, C.N.

2011-01-01

Lithium evaporation onto NSTX plasma facing components (PFC) has resulted in improved energy confinement, and reductions in the number and amplitude of edge-localized modes (ELMs) up to the point of complete ELM suppression. The associated PFC surface chemistry has been investigated with a novel plasma material interface probe connected to an in-vacuo surface analysis station. Analysis has demonstrated that binding of D atoms to the polycrystalline graphite material of the PFCs is fundamentally changed by lithium - in particular deuterium atoms become weakly bonded near lithium atoms themselves bound to either oxygen or the carbon from the underlying material. Surface dust inside NSTX has been detected in real-time using a highly sensitive electrostatic dust detector. In a separate experiment, electrostatic removal of dust via three concentric spiral-shaped electrodes covered by a dielectric and driven by a high voltage 3-phase waveform was evaluated for potential application to fusion reactors

Impact of Middle Eastern dust storms on indoor and outdoor composition of bioaerosol

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Soleimani, Zahra; Goudarzi, Gholamreza; Sorooshian, Armin; Marzouni, Mohammad Bagherian; Maleki, Heidar

2016-08-01

The presence of microbes in airborne aerosol particles, especially dust, is a major public health concern in desert regions. This study is the first of its kind to examine the effect of dust storms on indoor and outdoor microbial air quality at a hospital on the western side of Iran (city of Ahvaz), which is notorious for being highly vulnerable to dust emissions. Air samples were collected inside and outside of the hospital environment for six months, with the unique advantage of this study being that the region and duration of measurements allow for a clear comparison between dusty and normal days. On normal days, the average concentrations (outdoor/indoor) of bacteria and fungi were 423/329 cfu m-3 and 596/386 cfu m-3, respectively, which increased to 1257/406 cfu m-3 and 1116/550 cfu m-3 on dust event days. Indoor/Outdoor ratios for bacteria and fungi are lower on dust event days (0.26-0.60) versus normal days (0.44-0.95). Bacillus spp., Micrococcus spp., Streptomyces spp., and Staphylococcus spp. were the dominant bacteria both indoors and outdoors on normal and dust event days. Gram positive bacteria exhibited higher concentrations than Gram negative bacteria in both outdoor and indoor air samples as well as during both normal and dust event days. The data suggest that Gram positive bacteria are more resistant to undesirable outdoor conditions (e.g., high incident solar radiation) as compared to Gram negative ones. These results have implications for other populated arid regions where more stringent control of indoor air quality can greatly benefit public health.

Investigation of coal dust explosion hazard at the Nikola Tesla-A thermal power station

Energy Technology Data Exchange (ETDEWEB)

Golubovic, D

1987-10-01

Reports on investigations into coal dust explosion hazards in working places with high coal dust exposure, done in the Tesla-A thermal power station by Mining Institute of Belgrade specialists. Settled and floating coal dust concentrations were monitored for six months and samples analyzed for explosibility under lab conditions. Samples from transport and preparation facilities and the power station boiler house were taken. The entire plant was divided into 4 zones, depending on intensity of dust settlement and ventilation system. Coal dust generation varied from 0.3-65 g/min. Daily dust settlement ranged between 40 and 300 g/m/sup 2/. Total quantity of accumulated coal dust in the power plant ranged from 0.8-650 kg/day; 250 g/m/sup 3/ of coal dust may cause an explosion. Thus, a dangerous amount of coal dust, depending on work-site, will settle in 3.3.-21.8 days. Disturbance of settled dust may create explodable clouds. Details of measurements taken and data evaluation are included. 4 refs.

Investigations into the penetration and pressure drop of HEPA filter media during loading with submicron particle aerosols at high concentrations

International Nuclear Information System (INIS)

Leibold, H; Wilhelm, J.G.

1991-01-01

High Efficiency Particulate Air (HEPA) filters are typically employed in particle removal and retention within the air cleaning systems of clean rooms in the pharmaceutical, nuclear and semiconductor industries for dust concentrations of some μg/m 3 . Their extremely high removal efficiencies for submicron particles make them attractive candidates in complying with increasingly lower emission limits for industrial processes that involve dust concentrations of up to several g/m 3 . Cost-effective operation under such conditions requires the filter units to be recleanable. The recleanability of HEPA filter media depends not only on the operating conditions during the cleaning process but also on the filtration conditions during particle loading. The structure and location of the particles captured by the glass fiber matrix greatly affect the degree to which they can be subsequently dislodged and removed from the filter medium. Changes in filtration efficiency with service time for various particle diameters in the critical submicron size range, as well as the effects of filtration velocity on the increase in pressure drop, are important criteria with regard to recleaning HEPA filter units. Of special significance for the recleanability of HEPA filter media is knowledge of how operating conditions affect dust cake formation. (author)

Transformation of arsenic-rich copper smelter flue dust in contrasting soils: A 2-year field experiment.

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Jarošíková, Alice; Ettler, Vojtěch; Mihaljevič, Martin; Penížek, Vít; Matoušek, Tomáš; Culka, Adam; Drahota, Petr

2018-06-01

Dust emissions from copper smelters processing arsenic-bearing ores represent a risk to soil environments due to the high levels of As and other inorganic contaminants. Using an in situ experiment in four different forest and grassland soils (pH 3.2-8.0) we studied the transformation of As-rich (>50 wt% As) copper smelter dust over 24 months. Double polyamide bags with 1 g of flue dust were buried at different depths in soil pits and in 6-month intervals; then those bags, surrounding soil columns, and soil pore waters were collected and analysed. Dust dissolution was relatively fast during the first 6 months (5-34%), and mass losses attained 52% after 24 months. The key driving forces affecting dust dissolution were not only pH, but also the water percolation/retention in individual soils. Primary arsenolite (As 2 O 3 ) dissolution was responsible for high As release from the dust (to 72%) and substantial increase of As in the soil (to a 56 × increase; to 1500 mg kg -1 ). Despite high arsenolite solubility, this phase persisted in the dust after 2 years of exposure. Mineralogical investigation indicated that mimetite [Pb 5 (AsO 4 ) 3 (Cl,OH)], unidentified complex Ca-Pb-Fe-Zn arsenates, and Fe oxyhydroxides partly controlled the mobility of As and other metal(loid)s. Compared to As, other less abundant contaminants (Bi, Cu, Pb, Sb, Zn) were released into the soil to a lesser extent (8-40% of total). The relatively high mobility of As in the soil can be seen from decreases of bulk As concentrations after spring snowmelt, high water-extractable fractions with up to ∼50% of As(III) in extracts, and high As concentrations in soil pore waters. Results indicate that efficient controls of emissions from copper smelters and flue dust disposal sites are needed to prevent extensive contamination of nearby soils by persistent As. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dust exposure in workers from grain storage facilities in Costa Rica.

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Rodríguez-Zamora, María G; Medina-Escobar, Lourdes; Mora, Glend; Zock, Jan-Paul; van Wendel de Joode, Berna; Mora, Ana M

2017-08-01

About 12 million workers are involved in the production of basic grains in Central America. However, few studies in the region have examined the occupational factors associated with inhalable dust exposure. (i) To assess the exposure to inhalable dust in workers from rice, maize, and wheat storage facilities in Costa Rica; (ii) to examine the occupational factors associated with this exposure; and (iii) to measure concentrations of respirable and thoracic particles in different areas of the storage facilities. We measured inhalable (dust concentrations in 176 personal samples collected from 136 workers of eight grain storage facilities in Costa Rica. We also measured respirable (dust particles in several areas of the storage facilities. Geometric mean (GM) and geometric standard deviation (GSD) inhalable dust concentrations were 2.0mg/m 3 and 7.8 (range=dust concentrations were associated with job category [GM for category/GM for administrative staff and other workers (95% CI)=4.4 (2.6, 7.2) for packing; 20.4 (12.3, 34.7) for dehulling; 109.6 (50.1, 234.4) for unloading in flat bed sheds; 24.0 (14.5, 39.8) for unloading in pits; and 31.6 (18.6, 52.5) for drying], and cleaning task [15.8 (95% CI: 10.0, 26.3) in workers who cleaned in addition to their regular tasks]. Higher area concentrations of thoracic dust particles were found in wheat (GM and GSD=4.3mg/m 3 and 4.5) and maize (3.0mg/m 3 and 3.9) storage facilities, and in grain drying (2.3mg/m 3 and 3.1) and unloading (1.5mg/m 3 and 4.8) areas. Operators of grain storage facilities showed elevated inhalable dust concentrations, mostly above international exposure limits. Better engineering and administrative controls are needed. Copyright © 2017 Elsevier GmbH. All rights reserved.

Saharan dust event impacts on cloud formation and radiation over Western Europe

Directory of Open Access Journals (Sweden)

M. Bangert

2012-05-01

Full Text Available We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties.

The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l⁻¹ during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds.

Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected. This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to −75 W m⁻². Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80 W m⁻², and the incoming long-wave radiation at the surface was increased significantly in the order of +10 W m⁻².

The

Dust in fusion devices-a multi-faceted problem connecting high- and low-temperature plasma physics

International Nuclear Information System (INIS)

Winter, J

2004-01-01

Small particles with sizes between a few nanometers and a few 10 μm (dust) are formed in fusion devices by plasma-surface interaction processes. Though it is not a major problem today, dust is considered a problem that could arise in future long pulse fusion devices. This is primarily due to its radioactivity and due to its very high chemical reactivity. Dust formation is particularly pronounced when carbonaceous wall materials are used. Dust particles can be transported in the tokamak over significant distances. Radioactivity leads to electrical charging of dust and to its interaction with plasmas and electric fields. This may cause interference with the discharge but may also result in options for particle removal. This paper discusses some of the multi-faceted problems using information both from fusion research and from low-temperature dusty plasma work

Creation of Wood Dust during Wood Processing: Size Analysis, Dust Separation, and Occupational Health

Directory of Open Access Journals (Sweden)

Eva Mračková

2015-11-01

Full Text Available Mechanical separators and fabric filters are being used to remove airborne fine particles generated during the processing and handling of wood. Such particles might have a harmful effect on employee health, not only in small- but also in large-scale wood processing facilities. The amount of wood dust and its dispersion conditions vary according to geometric boundary conditions. Thus, the dispersion conditions could be changed by changing the linear size of the particles. Moreover, the smaller the particles are, the more harmful they can be. It is necessary to become familiar with properties, from a health point of view, of wood dust generated from processing. Wood dust has to be sucked away from the processing area. The fractional separation efficiency of wood dust can be improved using exhaust and filtering devices. Filtration efficiency depends on moisture content, particle size, and device performance. Because of the carcinogenicity of wood dust, the concentration of wood dust in air has to be monitored regularly. Based on the results hereof, a conclusion can be made that both mechanical separators of types SEA and SEB as well as the fabric filters with FINET PES 1 textile are suitable for the separation of wet saw dust from all types of wooden waste produced within the process.

Phthalate and PAH concentrations in dust collected from Danish homes and daycare centers

DEFF Research Database (Denmark)

Langer, Sarka; Weschler, Charles J.; Fischer, Andreas

2010-01-01

(diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), di(isobutyl) phthalate (DiBP), butyl benzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP)) and three PAHs (pyrene, benz[a]anthracene (B[a]A) and benzo[a]pyrene (B[a]P)). The three PAHs and DEHP were detected in dust samples from all sites, while...... DEP. DnBP, DiBP and BBzP were detected in more than 75% of the bedrooms and more than 90% of the daycare centers. The dust mass-fractions of both phthalates and PAHs were log-normally distributed. With the exception of DEP, the mass-fractions of phthalates in dust were higher in daycare centers than...... homes: PAH mass-fractions in dust were similar in the two locations. There was no correlation among the different phthalates in either homes or daycare centers. In contrast, the PAH were correlated with one another more strongly so in homes (R-2 = 0.80-0.90) than in daycare centers (R-2 = 0...

De-coupling interannual variations of vertical dust extinction over the Taklimakan Desert during 2007-2016 using CALIOP.

Science.gov (United States)

Nan, Yang; Wang, Yuxuan

2018-03-26

During the springtime, mineral dust from the Taklimakan Desert (TD) is lifted up to high altitudes and transported long distances by the westerlies. The vertical distributions of Taklimakan dust are important for both long-range transport and climate effects. In this study, we use CALIOP Level 3 dust extinction to describe interannual variation of dust extinction in TD aggregated at each 1km interval (1-2km, 2-3km, 3-4km, 4-5km and 5-6km) above mean sea level during springtime from 2007 to 2016. 87% of dust extinction over TD is concentrated at 1-4km taking a major composition of dust aerosol optical depth (AOD) and only 8.1% dust AOD is at 4-6km. Interannual variation of seasonal and monthly dust extinction at 1-4km is almost as same as dust AOD (R>0.99) but different from that at 4-6km (R are around 0.42). Our analysis provides observational evidence from CALIOP that vertical dust extinction over TD has distinctively different variability below and above 4km altitude and this threshold divides dust transport in TD into two systems. Taklimakan dust aerosols are more related to dust transport at high altitudes (4-10km) than low altitudes (0-4km) over downwind regions. High dust extinction below 4km over TD is necessary but not sufficient conditions to ensure dust transport easterly, while high dust extinction levels at 4-6km over TD are both necessary and sufficient conditions; such contrast leads to the de-coupled interannual variability seen by CALIOP. Copyright © 2018 Elsevier B.V. All rights reserved.

MODELING THERMAL DUST EMISSION WITH TWO COMPONENTS: APPLICATION TO THE PLANCK HIGH FREQUENCY INSTRUMENT MAPS

International Nuclear Information System (INIS)

Meisner, Aaron M.; Finkbeiner, Douglas P.

2015-01-01

We apply the Finkbeiner et al. two-component thermal dust emission model to the Planck High Frequency Instrument maps. This parameterization of the far-infrared dust spectrum as the sum of two modified blackbodies (MBBs) serves as an important alternative to the commonly adopted single-MBB dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. based on FIRAS and DIRBE. We also derive full-sky 6.'1 resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 μm data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.'1 FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to 3000 GHz. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration et al. single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz, and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anisotropy on small angular scales

Desert Dust Outbreaks in Southern Europe: Contribution to Daily PM10 Concentrations and Short-Term Associations with Mortality and Hospital Admissions

Science.gov (United States)

Stafoggia, Massimo; Zauli-Sajani, Stefano; Pey, Jorge; Samoli, Evangelia; Alessandrini, Ester; Basagaña, Xavier; Cernigliaro, Achille; Chiusolo, Monica; Demaria, Moreno; Díaz, Julio; Faustini, Annunziata; Katsouyanni, Klea; Kelessis, Apostolos G.; Linares, Cristina; Marchesi, Stefano; Medina, Sylvia; Pandolfi, Paolo; Pérez, Noemí; Querol, Xavier; Randi, Giorgia; Ranzi, Andrea; Tobias, Aurelio; Forastiere, Francesco

2015-01-01

Background: Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. Objectives: We aimed to estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 Southern European cities, distinguishing between PM10 originating from the desert and from other sources. Methods: We identified desert dust advection days in multiple Mediterranean areas for 2001–2010 by combining modeling tools, back-trajectories, and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. Results: On average, 15% of days were affected by desert dust at ground level (desert PM10 > 0 μg/m3). Most episodes occurred in spring–summer, with increasing gradient of both frequency and intensity north–south and west–east of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10 μg/m3 in non-desert and desert PM10 (lag 0–1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. Conclusions: PM10 originating from the desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections. Citation: Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, Cernigliaro A, Chiusolo M, Demaria M, Díaz J, Faustini A

Desert Dust Outbreaks in Southern Europe: Contribution to Daily PM₁₀ Concentrations and Short-Term Associations with Mortality and Hospital Admissions.

Science.gov (United States)

Stafoggia, Massimo; Zauli-Sajani, Stefano; Pey, Jorge; Samoli, Evangelia; Alessandrini, Ester; Basagaña, Xavier; Cernigliaro, Achille; Chiusolo, Monica; Demaria, Moreno; Díaz, Julio; Faustini, Annunziata; Katsouyanni, Klea; Kelessis, Apostolos G; Linares, Cristina; Marchesi, Stefano; Medina, Sylvia; Pandolfi, Paolo; Pérez, Noemí; Querol, Xavier; Randi, Giorgia; Ranzi, Andrea; Tobias, Aurelio; Forastiere, Francesco

2016-04-01

Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. We aimed to estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 Southern European cities, distinguishing between PM10 originating from the desert and from other sources. We identified desert dust advection days in multiple Mediterranean areas for 2001-2010 by combining modeling tools, back-trajectories, and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. On average, 15% of days were affected by desert dust at ground level (desert PM10 > 0 μg/m3). Most episodes occurred in spring-summer, with increasing gradient of both frequency and intensity north-south and west-east of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10 μg/m3 in non-desert and desert PM10 (lag 0-1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. PM10 originating from the desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections. Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, Cernigliaro A, Chiusolo M, Demaria M, Díaz J, Faustini A, Katsouyanni K, Kelessis AG, Linares C, Marchesi S, Medina S, Pandolfi P, P�

SVOC partitioning between the gas phase and settled dust indoors

Science.gov (United States)

Weschler, Charles J.; Nazaroff, William W.

2010-09-01

Semivolatile organic compounds (SVOCs) are a major class of indoor pollutants. Understanding SVOC partitioning between the gas phase and settled dust is important for characterizing the fate of these species indoors and the pathways by which humans are exposed to them. Such knowledge also helps in crafting measurement programs for epidemiological studies designed to probe potential associations between exposure to these compounds and adverse health effects. In this paper, we analyze published data from nineteen studies that cumulatively report measurements of dustborne and airborne SVOCs in more than a thousand buildings, mostly residences, in seven countries. In aggregate, measured median data are reported in these studies for 66 different SVOCs whose octanol-air partition coefficients ( Koa) span more than five orders of magnitude. We use these data to test a simple equilibrium model for estimating the partitioning of an SVOC between the gas phase and settled dust indoors. The results demonstrate, in central tendency, that a compound's octanol-air partition coefficient is a strong predictor of its abundance in settled dust relative to its gas phase concentration. Using median measured results for each SVOC in each study, dustborne mass fractions predicted using Koa and gas-phase concentrations correlate reasonably well with measured dustborne mass fractions ( R2 = 0.76). Combined with theoretical understanding of SVOC partitioning kinetics, the empirical evidence also suggests that for SVOCs with high Koa values, the mass fraction in settled dust may not have sufficient time to equilibrate with the gas phase concentration.

Assessment of occupational exposure to wood dust in the Polish furniture industry

Directory of Open Access Journals (Sweden)

Małgorzata Szewczyńska

2017-02-01

Full Text Available Background: Occupational exposure to wood dust can be responsible for many different harmful health effects, especially in workers employed in the wood industry. The assessment of wood dust adverse effects to humans, as well as the interpretation of its concentration measurements carried out to assess potential occupational exposure are very difficult. First of all, it is due to possible occurrence of different kind of wood dust in the workplace air, namely wood dust from dozens of species of trees belonging to 2 kinds of botanical gymnosperms and angiosperms, as well as to its different chemical composition. Material and Methods: Total dust and respirable wood dust in the workplace air in the furniture industry was determined using the filtration-gravimetric method in accordance with Polish Standards PN-Z-04030-05:1991 and PN-Z-04030-06:1991. Air samples were collected based on the principles of individual dosimetry. Results: Total dust concentrations were 0.84–13.92 mg/m3 and inhalable fraction concentrations, obtained after the conversion of total dust by applying a conversion factor of 1.59, were 1.34–22.13 mg/m3. Respirable fraction concentrations were 0.38–4.04 mg/m3, which makes approx. 25% of the inhalable fraction on average. The highest concentrations occurred in grinding and the lowest during milling processes of materials used in the manufacture of furniture. Conclusions: The results indicate that the share of respirable fraction in the inhalable fraction of wood dust is considerable. Due to the determination of the threshold limit value (TLV for the inhalable fraction of wood dust, it is necessary to replace the previously used samplers for total dust with samplers that provide quantitative separation of wood dust inhalable fractions in accordance with the convention of this fraction as defined in PN-EN 481:1998. Med Pr 2017;68(1:45–60

[Assessment of occupational exposure to wood dust in the Polish furniture industry].

Science.gov (United States)

Szewczyńska, Małgorzata; Pośniak, Małgorzata

2017-02-28

Occupational exposure to wood dust can be responsible for many different harmful health effects, especially in workers employed in the wood industry. The assessment of wood dust adverse effects to humans, as well as the interpretation of its concentration measurements carried out to assess potential occupational exposure are very difficult. First of all, it is due to possible occurrence of different kind of wood dust in the workplace air, namely wood dust from dozens of species of trees belonging to 2 kinds of botanical gymnosperms and angiosperms, as well as to its different chemical composition. Total dust and respirable wood dust in the workplace air in the furniture industry was determined using the filtration-gravimetric method in accordance with Polish Standards PN-Z-04030-05:1991 and PN-Z-04030-06:1991. Air samples were collected based on the principles of individual dosimetry. Total dust concentrations were 0.84-13.92 mg/m3 and inhalable fraction concentrations, obtained after the conversion of total dust by applying a conversion factor of 1.59, were 1.34-22.13 mg/m3. Respirable fraction concentrations were 0.38-4.04 mg/m3, which makes approx. 25% of the inhalable fraction on average. The highest concentrations occurred in grinding and the lowest during milling processes of materials used in the manufacture of furniture. The results indicate that the share of respirable fraction in the inhalable fraction of wood dust is considerable. Due to the determination of the threshold limit value (TLV) for the inhalable fraction of wood dust, it is necessary to replace the previously used samplers for total dust with samplers that provide quantitative separation of wood dust inhalable fractions in accordance with the convention of this fraction as defined in PN-EN 481:1998. Med Pr 2017;68(1):45-60. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Suspended particle and drug ingredient concentrations in hospital dispensaries and implications for pharmacists' working environments.

Science.gov (United States)

Inaba, Ryoichi; Hioki, Atsushi; Kondo, Yoshihiro; Nakamura, Hiroki; Nakamura, Mitsuhiro

2016-03-01

The aim of this study was to assess the present status of working environments for pharmacists, including the concentrations of suspended particles and suspended drug ingredients in dispensaries. We conducted a survey on the work processes and working environment in 15 hospital dispensaries, and measured the concentrations of suspended particles and suspended drug ingredients using digital dust counter and high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Of 25 types of powdered drugs that were frequently handled in the 15 dispensaries surveyed, 11 could be quantitatively determined. The amounts of suspended particles were relatively high, but below the reference value, in three dispensaries without dust collectors. The sedative-hypnotic drug zopiclone was detected in the suspended particles at one dispensary that was not equipped with dust collectors, and the antipyretic and analgesic drug acetaminophen was detected in two dispensaries equipped with dust collectors. There was no correlation between the daily number of prescriptions containing powdered drugs and the concentration of suspended particles in dispensaries. On the basis of the suspended particle concentrations measured, we concluded that dust collectors were effective in these dispensaries. However, suspended drug ingredients were detected also in dispensaries with dust collectors. These results suggest that the drug dust control systems of individual dispensaries should be properly installed and managed.

Research and development in dust and silicosis suppression

Energy Technology Data Exchange (ETDEWEB)

Breuer, H

1975-08-21

MAK values of 4 mg/m/sup 3/ for respirable dust containing quartz and 0.15 mg/m/sup 3/ for respirable quartz dust have been established for 5 years' exposure in West German hard coal mines. Routine gravimetric measurements were introduced in 1974 and these are supplemented by the digital Tyndallometer which indicates short-term variations. Gravimetric measurements have indicated the main sources of dust and improved dust suppression measures have considerably reduced respirable dust concentrations in some cases, e.g., by seam infusion, by spraying of the face machine path and at crushers, and by dedusters on heading machines.

The influence of organic-containing soil dust on ice nucleation and cloud properties

Science.gov (United States)

Hummel, Matthias; Grini, Alf; Berntsen, Terje K.; Ekman, Annica

2017-04-01

Natural mineral dust from desert regions is known to be the most important contributor to atmospheric ice-nucleating particles (INP) which induce heterogeneous ice nucleation in mixed-phase clouds. Its ability to nucleate ice effectively is shown by various laboratory (Hoose and Möhler 2012) and field results (DeMott et al. 2015) and its abundance in ice crystal residuals has also been shown (Cziczo et al. 2013). Thus it is an important player when representing mixed-phase clouds in climate models. MODIS satellite data indicate that 1 /4 of the global dust emission originates from semi-arid areas rather than from arid deserts (Ginoux et al. 2012). Here, organic components can mix with minerals within the soil and get into the atmosphere. These so-called 'soil dust' particles are ice-nucleating active at high sub-zero temperatures, i.e. at higher temperatures than pure desert dust (Steinke et al. 2016). In this study, soil dust is incorporated into the Norwegian Earth System Model (NorESM, Bentsen et al. 2013) and applied to a modified ice nucleation parameterization (Steinke et al. 2016). Its influence on the cloud ice phase is evaluated by comparing a control run, where only pure desert dust is considered, and a sensitivity experiment, where a fraction of the dust emissions are classified as soil dust. Both simulations are nudged to ERA-interim meteorology and they have the same loading of dust emissions. NorESM gives a lower annual soil dust emission flux compared to Ginoux et al. (2012), but the desert dust flux is similar to the MODIS-retrieved data. Although soil dust concentrations are much lower than desert dust, the NorESM simulations indicate that the annual INP concentrations from soil dust are on average lower by a just a factor of 4 than INP concentrations from pure desert dust. The highest soil dust INP concentrations occur at a lower height than for desert dust, i.e at warmer temperatures inside mixed-phase clouds. Furthermore, soil dust INP

Effect of changes in environment on the variation in elemental composition of airborne dust

International Nuclear Information System (INIS)

Miyamoto, Yutaka; Saito, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu

2004-01-01

For the research on environmental impact caused by nuclear activities, we are developing monitoring technique to measure radioactivity, isotopic and elemental composition in airborne dust, which contains nuclear materials and radioactive elements released from nuclear facilities. We focus on its elimination process such as wash-out by rainfall and adsorption to plants in the processes which affect the amounts and composition of the airborne dust. Recently at JAERI-Tokai, a number of pine trees to arrest sand shifting were cut down. This gave us a good opportunity to examine the effect of presence of the trees on the variation in elemental composition of airborne dust, therefore, we collected dust samples with a high-volume sampler before and after felling the trees, and analyzed them by means of instrumental neutron activation analysis. No change was observed in the amount, Al- and Sc- concentrations of the dust collected before and after felling the trees nearby the sampling site. There were correlations between the elemental concentration of Zn and that of Sb, and between Zn and As. These elements might originate from some by-products of social activities such as fly ashes. If found that the concentration of these elements after felling the trees decrease to 60% of the concentration before the works. The histograms of concentration of Cl in the airborne samples were compiled using the samples which the average of relative humidity in the period of the sample collection was 70-80%. The Cl concentration in the airdust after felling the trees at the seaside was three times higher than that concentration before the works. It found that the trees can eliminate more effectively the aerosols such as sea-salt than soil from the atmosphere. (author)

The management of house dust mite allergies

NARCIS (Netherlands)

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

1990-01-01

A safe and practical home sanitation procedure for the removal of house dust mites (Dermatophagoides pteronyssinus) and their allergens is described. The severity of mite infestation was assessed with the use of the Acarex test, which measures the concentration of guanine in house dust, and all

On supernovae as a source of interstellar dust. The current observational picture

International Nuclear Information System (INIS)

Dinerstein, H.L.

1984-01-01

Supernovae have been generally thought of as being effective agents for the destruction of ambient interstellar dust. The idea that supernovae may also be a source of dust has been of interest recently, and is attractive for a couple of reasons. The main motivation is to explain meteoritic inclusions with peculiar isotopic abundance ratios as supernova dust condensates predating the solar nebula. In addition, although the nucleation process is not fully understood, the high concentration of condensable elements in the supernova mantle suggests the possibility that grain formation could be very efficient. In this case, supernovae could be a major source of new grain cores to the interstellar medium. (author)

Fractal dust grains in plasma

International Nuclear Information System (INIS)

Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

2012-01-01

Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

Dust control for draglines

Energy Technology Data Exchange (ETDEWEB)

Grad, P.

2009-09-15

Monitoring dust levels inside draglines reveals room for improvement in how filtration systems are used and maintained. The Australian firm BMT conducted a field test program to measure airflow parameters, dust fallout rates and dust concentrations, inside and outside the machine house, on four draglines and one shovel. The study involved computational fluid dynamics (CFD) simulations. The article describes how the tests were made and gives results. It was not possible to say which of the two main filtration systems currently used on Australian draglines - Dynavane or Floseps - performs better. It would appear that more frequent maintenance and cleaning would increase the overall filtration performance and systems could be susceptible to repeat clogging in a short time. 2 figs., 1 photos.

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

Science.gov (United States)

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

2016-05-01

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

Mechanical and Thermal Properties of R-High Density Polyethylene Composites Reinforced with Wheat Straw Particleboard Dust and Basalt Fiber

Directory of Open Access Journals (Sweden)

Min Yu

2018-01-01

Full Text Available The effect of individual and combined particleboard dust (PB dust and basalt fibers (BFs on mechanical and thermal expansion performance of the filled virgin and recycled high density polyethylene (HDPE composites was studied. It was shown that the use of PB dust had a positive effect on improving mechanical properties and on reducing linear coefficient of thermal expansion (LCTE values of filled composites, because the adhesive of the particle board held the wheat straw fibers into bundles, which made PB dust have a certain aspect ratio and high strength. Compared with the commonly used commercial WPC products, the flexural strength of PB dust/VHDPE, PB dust/RHDPE, and PB dust/VHDPE/RHDEPE at 40 wt% loading level increased by 79.9%, 41.5%, and 53.9%, respectively. When 40 wt% PB dust was added, the crystallization degree of the composites based on three matrixes decreased to 72.5%, 45.7%, and 64.1%, respectively. The use of PB dust can help lower the composite costs and increase its recyclability. Mechanical properties and LCTE values of composites with combined BF and PB dust fillers varied with PB dust and BF ratio at a given total filler loading level. As the BF portion of the PB dust/BF fillers increased, the LCTE values decreased markedly, which was suggested to be able to achieve a desirable dimensional stability for composites. The process provides a useful route to further recycling of agricultural wastes.

Geochemical evidence on the source regions of Tibetan Plateau dusts during non-monsoon period in 2008/09

Science.gov (United States)

Li, C.; Kang, S.; Zhang, Q.; Gao, S.

2012-12-01

Geochemical characteristics, source regions and related transport patterns of dust over the Tibetan Plateau (TP) are still unclear. To address these issues, major (Na, Mg, Al, K and Ca), trace (e.g. Li, Cr, Ni, As, Cd, Cs, Pb and U) and rare earth elements of dust samples from five snow-pits over the TP and its fringe areas during the non-monsoon period in 2008/2009 were analyzed. The results indicate that rare earth element compositions of snow-pit dust are similar to those of the upper continental crust. Enrichment factors of all the elements of snow-pit dust are identical to those of the pollution elements (e.g. Cu and Ni) and elements like Li, As and Cs that are concentrated in surface soils. In contrast, concentrations of some typical pollution elements (e.g. Cr and Cd) of snow pit dust are lower than those of dusts derived from the Sahara Desert and the Thar Desert surrounding the TP. Additionally, the compositions of rare earth elements and high field strength elements (Hf, Zr and Nb) of snow-pit dust are also similar to those of surface soils and different from dusts of these two deserts. The combined evidence, including dust transport patterns around the TP, supports the conclusion that the TP itself is the main source region of snow-pit dusts of the inner TP. It is unlikely that those particle-bound pollutants are transported into the TP from outside sources during the non-monsoon period. Ratios of Ce/Sm against Eu/Sm for the snow-pit dust, fine dust from the Sahara desert (A), and ratios of Ce/Er against Eu/Er for the snow-pit dust, fine dust from the Thar Desert (B). Dust from Sahasa cannot penetrate into the TP and transport only along the Himalayas at south and the Tianshan at north due to their high elevation

Dust-Plasma Interactions

International Nuclear Information System (INIS)

Rosenberg, Marelene

2005-01-01

Our theoretical research on dust-plasma interactions has concentrated on three main areas: (a)studies of grain charging and applications; (b) waves and instabilities in weakly correlated dusty plasma with applications to space and laboratory plasmas; (c) waves in strongly coupled dusty plasmas.

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

African Journals Online (AJOL)

ADOWIE PERE

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

[Analysis and prevention of dust pollution caused by 5 common prosthetic materials].

Science.gov (United States)

Yang, Xiang-Wen; Wei, Bin; Zhu, Cao-Yun; Qian, Liang; Li, Yi-Han

2017-10-01

To analyze and evaluate dust pollution in prosthodontic clinic and make proposal for reasonable protection. This study analyzed the particle size, element composition and dust concentration of 5 materials which were commonly used in dental restorations (veneering ceramics, cobalt-chromium alloy, photosensitive plastic, hard base resin, advanced artificial teeth) by using scanning electron microscopy (SEM), X-ray energy dispersive spectrometer（EDS） and dust concentration laser tester, in order to assess the effects of prosthodontic dust posed on medical staff health and put forward reasonable suggestions for prevention and control of dust pollution. The particle size of veneering ceramics, cobalt-chromium alloy, photosensitive plastic, hard base resin and advanced artificial teeth was (2.15±3.00), (33.78±24.33), (7.78±11.86), (31.16±44.35) and (28.45±39.21)μm, respectively. The time weighted average respirable dust concentration of veneering ceramics was 0.393 mg/m 2 which was beyond the scope of national security. Dust pollution is serious in prosthodontic clinic to which we should pay more attention and take appropriate prevention measures.

Parameterizing the interstellar dust temperature

Science.gov (United States)

Hocuk, S.; Szűcs, L.; Caselli, P.; Cazaux, S.; Spaans, M.; Esplugues, G. B.

2017-08-01

The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in astrochemical studies that governs the rate at which molecules form on dust. In 3D (magneto)hydrodynamic simulations often a simple expression for the dust temperature is adopted, because of computational constraints, while astrochemical modelers tend to keep the dust temperature constant over a large range of parameter space. Our aim is to provide an easy-to-use parametric expression for the dust temperature as a function of visual extinction (AV) and to shed light on the critical dependencies of the dust temperature on the grain composition. We obtain an expression for the dust temperature by semi-analytically solving the dust thermal balance for different types of grains and compare to a collection of recent observational measurements. We also explore the effect of ices on the dust temperature. Our results show that a mixed carbonaceous-silicate type dust with a high carbon volume fraction matches the observations best. We find that ice formation allows the dust to be warmer by up to 15% at high optical depths (AV> 20 mag) in the interstellar medium. Our parametric expression for the dust temperature is presented as Td = [ 11 + 5.7 × tanh(0.61 - log 10(AV) ]χuv1/5.9, where χuv is in units of the Draine (1978, ApJS, 36, 595) UV field.

Antimicrobial Chemicals Are Associated with Elevated Antibiotic Resistance Genes in the Indoor Dust Microbiome.

Science.gov (United States)

Hartmann, Erica M; Hickey, Roxana; Hsu, Tiffany; Betancourt Román, Clarisse M; Chen, Jing; Schwager, Randall; Kline, Jeff; Brown, G Z; Halden, Rolf U; Huttenhower, Curtis; Green, Jessica L

2016-09-20

Antibiotic resistance is increasingly widespread, largely due to human influence. Here, we explore the relationship between antibiotic resistance genes and the antimicrobial chemicals triclosan, triclocarban, and methyl-, ethyl-, propyl-, and butylparaben in the dust microbiome. Dust samples from a mixed-use athletic and educational facility were subjected to microbial and chemical analyses using a combination of 16S rRNA amplicon sequencing, shotgun metagenome sequencing, and liquid chromatography tandem mass spectrometry. The dust resistome was characterized by identifying antibiotic resistance genes annotated in the Comprehensive Antibiotic Resistance Database (CARD) from the metagenomes of each sample using the Short, Better Representative Extract Data set (ShortBRED). The three most highly abundant antibiotic resistance genes were tet(W), blaSRT-1, and erm(B). The complete dust resistome was then compared against the measured concentrations of antimicrobial chemicals, which for triclosan ranged from 0.5 to 1970 ng/g dust. We observed six significant positive associations between the concentration of an antimicrobial chemical and the relative abundance of an antibiotic resistance gene, including one between the ubiquitous antimicrobial triclosan and erm(X), a 23S rRNA methyltransferase implicated in resistance to several antibiotics. This study is the first to look for an association between antibiotic resistance genes and antimicrobial chemicals in dust.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

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

International Nuclear Information System (INIS)

Shi Guitao; Chen Zhenlou; Xu Shiyuan; Zhang Ju; Wang Li; Bi Chunjuan; Teng Jiyan

2008-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-11-15

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

Light scattering and absorption properties of dust particles retrieved from satellite measurements

International Nuclear Information System (INIS)

Hu, R.-M.; Sokhi, R.S.

2009-01-01

We use the radiative transfer model and chemistry transport model to improve our retrievals of dust optical properties from satellite measurements. The optical depth and absorbing optical depth of mineral dust can be obtained from our improved retrieval algorithm. We find the nonsphericity and absorption of dust particles strongly affect the scattering signatures such as phase function and polarization at the ultraviolet wavelengths. From our retrieval results, we find the high levels of dust concentration occurred over most desert regions such as Saharan and Gobi deserts. The dust absorption is found to be sensitive to mineral chemical composition, particularly the fraction of strongly absorbing dust particles. The enhancement of polarization at the scattering angles exceeding 120 0 is found for the nonspherical dust particles. If the polarization is neglected in the radiative transfer calculation, a maximum 50 percent error is introduced for the case of forward scattering and 25 percent error for the case of backscattering. We suggest that the application of polarimeter at the ultraviolet wavelengths has the great potential to improve the satellite retrievals of dust properties. Using refined optical model and radiative transfer model to calculate the solar radiative forcing of dust aerosols can reduce the uncertainties in aerosol radiative forcing assessment.

Road dust from pavement wear and traction sanding

Energy Technology Data Exchange (ETDEWEB)

Kupiainen, K.

2007-07-01

Vehicles affect the concentrations of ambient airborne particles through exhaust emissions, but particles are also formed in the mechanical processes in the tire-road interface, brakes, and engine. Particles deposited on or in the vicinity of the road may be re-entrained, or resuspended, into air through vehicle-induced turbulence and shearing stress of the tires. A commonly used term for these particles is 'road dust'. The processes affecting road dust emissions are complex and currently not well known. Road dust has been acknowledged as a dominant source of PM10 especially during spring in the sub-arctic urban areas, e.g. in Scandinavia, Finland, North America and Japan. The high proportion of road dust in sub-arctic regions of the world has been linked to the snowy winter conditions that make it necessary to use traction control methods. Traction control methods include dispersion of traction sand, melting of ice with brine solutions, and equipping the tires with either metal studs (studded winter tires), snow chains, or special tire design (friction tires). Several of these methods enhance the formation of mineral particles from pavement wear and/or from traction sand that accumulate in the road environment during winter. When snow and ice melt and surfaces dry out, traffic-induced turbulence makes some of the particles airborne. A general aim of this study was to study processes and factors underlying and affecting the formation and emissions of road dust from paved road surfaces. Special emphasis was placed on studying particle formation and sources during tire road interaction, especially when different applications of traction control, namely traction sanding and/or winter tires were in use. Respirable particles with aerodynamic diameter below 10 micrometers (PM10) have been the main concern, but other size ranges and particle size distributions were also studied. The following specific research questions were addressed: (i) How do traction

Systematic characterization of structural, dynamical and electrical properties of dust devils and implications for dust lifting processes

Science.gov (United States)

Franzese, Gabriele; Esposito, Francesca; Lorenz, Ralph D.; Popa, Ciprian; Silvestro, Simone; Deniskina, Natalia; Cozzolino, Fabio

2017-04-01

Dust devils are convective vortices able to lift sand and dust grains from the soil surface, even in conditions of low wind speed environment. They have been observed not only on Earth but also on other planets of the solar system; in particular, they are largely studied on Mars. Indeed, the contribution of the dust devils to the Martian climate is a highly debated question. In order to investigate this topic, it is important to understand the nature of the dust lifting mechanism by the vortex and characterize the induced electric field. As part of the development process of DREAMS, the meteorological station on board the Schiapparelli lander of the ExoMars 2016 mission, and of the Dust complex package of the ExoMars 2020 mission, we performed various field campaigns in the Sahara desert (Tafilalt region, Morocco). We deployed a fully equipped meteorological station and, during the 2014 summer, we observed three months of dust devils activity, collecting almost six hundreds events. For each dust devil, we monitored the horizontal wind speed and direction, the vertical wind speed, the pressure drop due to the vortex core, the temperature, the induced electric field and the concentration of dust lifted. This data set is unique in literature and represents up to now the most comprehensive one available for the dusty convective vortices. Here we will present the analysis of the Moroccan data with particular emphasis on the study of the atmospheric electric field variations due to the passage of the vortices. The distribution of the vortex parameters (wind speed and direction, pressure, E-field and dust lifted) are showed and compared, when possible, to the ones observed by the Martian surveys. The connection between the E-field and the other parameters will be presented. In the terrestrial environment, the development of the convective vortices is restricted by the presence of the vegetation and of the urban areas, hence dust devils can impact the climate only on local

Dust Quantization and Effects on Agriculture Over Uttar Pradesh, India

Science.gov (United States)

Munshi, Pavel; Tiwari, Shubhansh

2017-01-01

Dust plays a very important role in the atmosphere and the biosphere. In this communication, the effect of atmospheric dust on the yields of certain crops grown in Uttar Pradesh, India is assessed. Coherent physical and thermodynamic fingerprints of dust parameters such as from Satellite data- KALPANA-1, MODIS, OMI, CALIPSO; Model data- DREAM, HYSPLIT, ECMWF; have been considered to run the APSIM model to derive the impacts. This paper assesses dust as a physical atmospheric phenomenon including its Long Range Transport (LRT) and dispersion along with considerable variations of Aerosol Optical Depths (AODs) over the subcontinent of India. While AODs significantly increase by more dust concentration, the local dispersion of pollutants is a major concern with deposition of atmospheric dust such as sulphates and other chemical constituents that affect agricultural land. An approach in atmospheric physics is also taken to parameterize the model outputs. This communication indicates dust to be a positive factor for the cultivation of certain crops such as wheat, maize in the experimental location. Initial results suggest that LRT dust is a viable counterpart to decrease the concentration of soil acidity and related parameters thus enhancing the vitality of crops.

Toxicity of lunar dust assessed in inhalation-exposed rats.

Science.gov (United States)

Lam, Chiu-wing; Scully, Robert R; Zhang, Ye; Renne, Roger A; Hunter, Robert L; McCluskey, Richard A; Chen, Bean T; Castranova, Vincent; Driscoll, Kevin E; Gardner, Donald E; McClellan, Roger O; Cooper, Bonnie L; McKay, David S; Marshall, Linda; James, John T

2013-10-01

Humans will again set foot on the moon. The moon is covered by a layer of fine dust, which can pose a respiratory hazard. We investigated the pulmonary toxicity of lunar dust in rats exposed to 0, 2.1, 6.8, 20.8 and 60.6 mg/m(3) of respirable-size lunar dust for 4 weeks (6 h/day, 5 days/week); the aerosols in the nose-only exposure chambers were generated from a jet-mill ground preparation of a lunar soil collected during the Apollo 14 mission. After 4 weeks of exposure to air or lunar dust, groups of five rats were euthanized 1 day, 1 week, 4 weeks or 13 weeks after the last exposure for assessment of pulmonary toxicity. Biomarkers of toxicity assessed in bronchoalveolar fluids showed concentration-dependent changes; biomarkers that showed treatment effects were total cell and neutrophil counts, total protein concentrations and cellular enzymes (lactate dehydrogenase, glutamyl transferase and aspartate transaminase). No statistically significant differences in these biomarkers were detected between rats exposed to air and those exposed to the two low concentrations of lunar dust. Dose-dependent histopathology, including inflammation, septal thickening, fibrosis and granulomas, in the lung was observed at the two higher exposure concentrations. No lesions were detected in rats exposed to ≤6.8 mg/m(3). This 4-week exposure study in rats showed that 6.8 mg/m(3) was the highest no-observable-adverse-effect level (NOAEL). These results will be useful for assessing the health risk to humans of exposure to lunar dust, establishing human exposure limits and guiding the design of dust mitigation systems in lunar landers or habitats.

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

Science.gov (United States)

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

2016-01-01

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

Asian Dust Storm Outbreaks: A Satellite-Surface Perspective

Science.gov (United States)

Tsay, Si-Chee

2006-01-01

Airborne dusts from northern China contribute a significant part of the air quality problem and, to some extent, regional climatic impact in Asia during springtime. Asian dust typically originates in desert areas far from polluted urban regions. During the transport, dust layers can interact with anthropogenic sulfate and soot aerosols from heavily polluted urban areas. Added to the complex effects of clouds and natural marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from the source. Thus, understanding the unique temporal and spatial variations of Asian dust is of special importance in regional-to-global climate issues (e.g., radiative forcing, hydrological cycle, and primary biological productivity in the mid-Pacific Ocean, etc.), as well as societal concerns (e.g., adverse health effects to humans). The Asian dust and air pollution aerosols can be detected by its colored appearance on current Earth observing satellites (e.g., MODIS, SeaWiFS, TOMS, etc.) and its evolution monitored by satellites and surface network (e.g. AERONET, SKY NET, MPLNET, etc.). Recently, many field campaigns (e.g., ACE-Asia-2001, TRACEP-2001, ADE-2002 & -2003, APEX-2001 & -2003, etc.) were designed and executed to study the compelling variability in spatial and temporal scale of both pollution-derived and naturally occurring aerosols, which often exist in high concentrations over eastern Asia and along the rim of the western Pacific. I will present an overview of the outbreak of Asian dust storms from space and surface observations and to address the climatic effects and societal impacts.

Intense dust episodes in the Mediterranean and possible effects on atmospheric lapse rates

Science.gov (United States)

Hatzianastassiou, Nikos; Gkikas, Antonis; Papadimas, Christos D.; Gavrouzou, Maria

2016-04-01

Dust aerosols are major contributor to the atmospheric particulate matter, having significant effects on climate and weather patterns as well as on human health, not to mention others like agriculture or ocean chlorophyll. Moreover, these effects are maximized under conditions of massive dust concentration in the atmosphere, namely dust episodes or events. Such events are caused by uplifting and transport of dust from arid and semi-arid areas under favorable synoptic conditions. The Mediterranean basin, nearby to the greatest world deserts of North Africa and Middle East, frequently undergoes dust episodes. During such Mediterranean episodes, the number and mass concentration of dust is high, due to the proximity of its source areas. The dust episodes, through the direct interaction of dust primarily withthe shortwave but also with longwave radiation can lead to strong local warming in the atmosphere, possibly causing temperature inversion during daytime. The existence of such temperature inversions, associated with intense dust episodes in the Mediterranean, is the focus in this study. The methodology followed to achieve the scientific goal of the study consists in the use of a synergy of different data. This synergy enables: (i) the determination of intense dust episodes over the Mediterranean, (ii) the investigation and specification of temperature lapse rates and inversions during the days of dust episodes and (iii) the identification of vertical distribution of aerosols in the atmosphere over specific locations during the days of the episodes. These objectives are achieved through the use of data from: (i) the AERosol Robotic NETwork (AERONET) network, (ii) the Upper Air Observations (radiosondes) database of the University of Wyoming (UoW) and (iii) the European Aerosol Research Lidar Network (EARLINET) database. The study period spans the years from 2000 to 2013, constrained by the data availability of the databases. A key element of the methodology is the

Dust retaining properties of leaves of some tree species

Energy Technology Data Exchange (ETDEWEB)

Gusev, M I

1960-05-01

A study was made in Tashkent, Russia of the dust-retaining power of leaves of several tree species. Investigations were made in a park where these tree species were growing in close proximity, exposed to the effects of dust from the main city street and from the highway passing through the park. Observations on the dust-retaining power of leaves were made mostly during the summer and fall months. The dust-retaining power of leaves of different tree species varied with the dust concentration in the air. In the summer and fall when rains are scarce a steady accumulation of dust was observed on the surface of the leaves. 1 table.

The effect of mineral dust and soot aerosols on ice microphysics near the foothills of the Himalayas: A numerical investigation

Science.gov (United States)

Hazra, Anupam; Padmakumari, B.; Maheskumar, R. S.; Chen, Jen-Ping

2016-05-01

This study investigates the influence of different ice nuclei (IN) species and their number concentrations on cloud ice production. The numerical simulation with different species of ice nuclei is investigated using an explicit bulk-water microphysical scheme in a Mesoscale Meteorological Model version 5 (MM5). The species dependent ice nucleation parameterization that is based on the classical nucleation theory has been implemented into the model. The IN species considered include dust and soot with two different concentrations (Low and High). The simulated cloud microphysical properties like droplet number concentration and droplet effective radii as well as macro-properties (equivalent potential temperature and relative humidity) are comparable with aircraft observations. When higher dust IN concentrations are considered, the simulation results showed good agreement with the cloud ice and cloud water mixing ratio from aircraft measurements during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX) and Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. Relative importance of IN species is shown as compared to the homogeneous freezing nucleation process. The tendency of cloud ice production rates is also analyzed and found that dust IN is more efficient in producing cloud ice when compared to soot IN. The dust IN with high concentration can produce more surface precipitation than soot IN at the same concentration. This study highlights the need to improve the ice nucleation parameterization in numerical models.

Lunar Dust Mitigation Screens

Science.gov (United States)

Knutson, Shawn; Holloway, Nancy

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

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

Science.gov (United States)

Abafe, Ovokeroye A; Martincigh, Bice S

2016-04-01

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

Transpacific Transport of Dust to North American High-Elevation Sites: Integrated Dataset and Model Outputs

Science.gov (United States)

Kassianov, E.; Pekour, M. S.; Flynn, C. J.; Berg, L. K.; Beranek, J.; Zelenyuk, A.; Zhao, C.; Leung, L. R.; Ma, P. L.; Riihimaki, L.; Fast, J. D.; Barnard, J.; Hallar, G. G.; McCubbin, I.; Eloranta, E. W.; McComiskey, A. C.; Rasch, P. J.

2017-12-01

Understanding the effects of dust on the regional and global climate requires detailed information on particle size distributions and their changes with distance from the source. Awareness is now growing about the tendency of the dust coarse mode with moderate ( 3.5 µm) volume median diameter (VMD) to be rather insensitive to complex removal processes associated with long-range transport of dust from the main sources. Our study, with a focus on the transpacific transport of dust, demonstrates that the impact of coarse mode aerosol (VMD 3µm) is well defined at the high-elevation mountain-top Storm Peak Laboratory (SPL, about 3.2 km MSL) and nearby Atmospheric Radiation Measurement (ARM) Climate Research Facility Mobile Facility (AMF) during March 2011. Significant amounts of coarse mode aerosol are also found at the nearest Aerosol Robotic Network (AERONET) site. Outputs from the high-resolution Weather Research and Forecasting (WRF) Model coupled with chemistry (WRF-Chem) show that the major dust event is likely associated with transpacific transport of Asian and African plumes. Satellite data, including the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) aerosol optical depth (AOD) and plume height from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar data provide the observational support of the WRF-Chem simulations. Our study complements previous findings by indicating that the quasi-static nature of the coarse mode appears to be a reasonable approximation for Asian and African dust despite expected frequent orographic precipitation over mountainous regions in the western United States.

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

International Nuclear Information System (INIS)

Branquinho, Cristina; Gaio-Oliveira, Gisela; Augusto, Sofia; Pinho, Pedro; Maguas, Cristina; Correia, Otilia

2008-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-01-15

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

An analysis of the dust deposition on solar photovoltaic modules.

Science.gov (United States)

Styszko, Katarzyna; Jaszczur, Marek; Teneta, Janusz; Hassan, Qusay; Burzyńska, Paulina; Marcinek, Ewelina; Łopian, Natalia; Samek, Lucyna

2018-03-29

Solid particles impair the performance of the photovoltaic (PV) modules. This results in power losses which lower the efficiency of the system as well as the increases of temperature which additionally decreases the performance and lifetime. The deposited dust chemical composition, concentration and formation of a dust layer on the PV surface differ significantly in reference to time and location. In this study, an evaluation of dust deposition on the PV front cover glass during the non-heating season in one of the most polluted European cities, Kraków, was performed. The time-dependent particle deposition and its correlation to the air pollution with particulate matter were analysed. Dust deposited on several identical PV modules during variable exposure periods (from 1 day up to 1 week) and the samples of total suspended particles (TSP) on quartz fibre filters using a low volume sampler were collected during the non-heating season in the period of 5 weeks. The concentration of TSP in the study period ranged between 12.5 and 60.05 μg m -3 while the concentration of PM10 observed in the Voivodeship Inspectorate of Environmental Protection traffic station, located 1.2 km from the TSP sampler, ranged from 14 to 47 μg m -3 . It was revealed that dust deposition density on a PV surface ranged from 7.5 to 42.1 mg m -2 for exposure periods of 1 day while the measured weekly dust deposition densities ranged from 25.8 to 277.0 mg m -2 . The precipitation volume and its intensity as well as humidity significantly influence the deposited dust. The rate of dust accumulation reaches approximately 40 mg m -2 day -1 in the no-precipitation period and it was at least two times higher than fluxes calculated on the basis of PM10 and TSP concentrations which suggest that additional forces such as electrostatic forces significantly influence dust deposition.

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

Energy Technology Data Exchange (ETDEWEB)

Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J., E-mail: hhwang@cfa.harvard.edu, E-mail: sandrews@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-11-01

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

Cosmological simulation with dust formation and destruction

Science.gov (United States)

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

2018-06-01

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

THE VISUALIZATION METHOD OF THE 3D CONCENTRATION DISTRIBUTION OF ASIAN DUST IN THE GOOGLE EARTH

Directory of Open Access Journals (Sweden)

W. Okuda

2012-07-01

Full Text Available The Asian dust (called "Kosa" in Japan transported from desert areas in the northern China often covers over East Asia in the late winter and spring seasons. In this study, first of all, for dust events observed at various places in Japan on April 1, 2007 and March 21, 2010, the long-range transport simulation of Asian dust from desert areas in the northern China to Japan is carried out. Next, the method for representing 3D dust clouds by means of the image overlay functionality provided in the Google Earth is described. Since it is very difficult to display 3D dust clouds along the curvature of the Earth on the global scale, the 3D dust cloud distributed at the altitude of about 6300m was divided into many thin layers, each of which is the same thickness. After each of layers was transformed to the image layer, each image layer was displayed at the appropriate altitude in the Google Earth. Thus obtained image layers were displayed every an hour in the Google Earth. Finally, it is shown that 3D Asian dust clouds generated by the method described in this study are represented as smooth 3D cloud objects even if we looked at Asian dust clouds transversely in the Google Earth.

HIGH-REDSHIFT DUST OBSCURED GALAXIES: A MORPHOLOGY-SPECTRAL ENERGY DISTRIBUTION CONNECTION REVEALED BY KECK ADAPTIVE OPTICS

International Nuclear Information System (INIS)

Melbourne, J.; Matthews, K.; Soifer, B. T.

2009-01-01

A simple optical to mid-IR color selection, R - [24]>14, i.e., f ν (24 μm)/f ν (R) ∼> 1000, identifies highly dust obscured galaxies (DOGs) with typical redshifts of z ∼ 2 ± 0.5. Extreme mid-IR luminosities (L IR > 10 12-14 ) suggest that DOGs are powered by a combination of active galactic nuclei (AGNs) and star formation, possibly driven by mergers. In an effort to compare their photometric properties with their rest-frame optical morphologies, we obtained high-spatial resolution (0.''05-0.''1) Keck Adaptive Optics K'-band images of 15 DOGs. The images reveal a wide range of morphologies, including small exponential disks (eight of 15), small ellipticals (four of 15), and unresolved sources (two of 15). One particularly diffuse source could not be classified because of low signal-to-noise ratio. We find a statistically significant correlation between galaxy concentration and mid-IR luminosity, with the most luminous DOGs exhibiting higher concentration and smaller physical size. DOGs with high concentration also tend to have spectral energy distributions (SEDs) suggestive of AGN activity. Thus, central AGN light may be biasing the morphologies of the more luminous DOGs to higher concentration. Conversely, more diffuse DOGs tend to show an SED shape suggestive of star formation. Two of 15 in the sample show multiple resolved components with separations of ∼1 kpc, circumstantial evidence for ongoing mergers.

Dust characterisation for hot gas filters

Energy Technology Data Exchange (ETDEWEB)

Dockter, B.; Erickson, T.; Henderson, A.; Hurley, J.; Kuehnel, V.; Katrinak, K.; Nowok, J.; O`Keefe, C.; O`Leary, E.; Swanson, M.; Watne, T. [University of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center (UNDEERC)

1998-03-01

Hot gas filtration to remove particulates from the gas flow upstream of the gas turbine is critical to the development of many of the advanced coal-fired power generation technologies such as the Air Blown Gasification Cycle (ABGC), a hybrid gasification combined cycle being developed in the UK. Ceramic candle filters are considered the most promising technology for this purpose. Problems of mechanical failure and of `difficult-to-clean` dusts causing high pressure losses across the filter elements need to be solved. The project investigated the behaviour of high-temperature filter dusts, and the factors determining the ease with which they can be removed from filters. The high-temperature behaviour of dusts from both combustion and gasification systems was investigated. Dust samples were obtained from full-scale demonstration and pilot-scale plant operating around the world. Dust samples were also produced from a variety of coals, and under several different operating conditions, on UNDEERC`s pilot-scale reactor. Key factors affecting dust behaviour were examined, including: the rates of tensile strength developing in dust cakes; the thermochemical equilibria pertaining under filtration conditions; dust adhesivity on representative filter materials; and the build-up and cleaning behaviour of dusts on representative filter candles. The results obtained confirmed the importance of dust temperature, dust cake porosity, cake liquid content, and particle size distribution in determining the strength of a dust cake. An algorithm was developed to indicate the likely sticking propensity of dusts as a function of coal and sorbent composition and combustion conditions. This algorithm was incorporated into a computer package which can be used to judge the degree of difficulty in filter cleaning that can be expected to arise in a real plant based on operating parameters and coal analyzes. 6 figs.

Vertical transport of desert particulates by dust devils and clear thermals

International Nuclear Information System (INIS)

Sinclair, P.C.

1974-01-01

While the vertical and horizontal transport of natural surface material by dust devils is not in itself a critical environmental problem, the transport and downwind fallout of toxic or hazardous materials from dust devil activity may be a contributing factor in the development of future ecological-biological problems. Direct quantitative measurements of the dust particle size distribution near and within the visible dust devil vortex and analyses of the upper level clear thermal plume have been made to provide estimates of the vertical and horizontal transport of long half-life radioactive substances such as plutonium. Preliminary measurements and calculations of dust concentrations within dust devils indicate that over 7 x 10 3 tons of desert dust and sand may be transported downwind from an area 285 km 2 during an average dust devil season (May to August). Near the ground these dust concentrations contain particles in the size range from approximately 1 μm to 250 μm diameter. Since the vertical velocity distribution greatly exceeds the particle(s) fall velocities, the detrainment of particles within the vortex is controlled primarily by the spatial distribution of the radial (v/sub r/) and tangential (v/sub theta/) velocity fields. Above the visible dust devil vortex, a clear thermal plume may extend upward to 15,000 to 18,000 ft MSL. A new airborne sampling and air data system has been developed to provide direct measurements of the dust concentration and air motion near and within the upper thermal plume. The air sampler has been designed to operate isokinetically over a considerable portion of the low-speed flight regime of a light aircraft. A strapped down, gyro-reference platform and a boom-vane system is used to determine the vertical air motions as well as the temperature and turbulence structure within the thermal plume. (U.S.)

Quantifying Anthropogenic Dust Emissions

Science.gov (United States)

Webb, Nicholas P.; Pierre, Caroline

2018-02-01

Anthropogenic land use and land cover change, including local environmental disturbances, moderate rates of wind-driven soil erosion and dust emission. These human-dust cycle interactions impact ecosystems and agricultural production, air quality, human health, biogeochemical cycles, and climate. While the impacts of land use activities and land management on aeolian processes can be profound, the interactions are often complex and assessments of anthropogenic dust loads at all scales remain highly uncertain. Here, we critically review the drivers of anthropogenic dust emission and current evaluation approaches. We then identify and describe opportunities to: (1) develop new conceptual frameworks and interdisciplinary approaches that draw on ecological state-and-transition models to improve the accuracy and relevance of assessments of anthropogenic dust emissions; (2) improve model fidelity and capacity for change detection to quantify anthropogenic impacts on aeolian processes; and (3) enhance field research and monitoring networks to support dust model applications to evaluate the impacts of disturbance processes on local to global-scale wind erosion and dust emissions.

The role of endotoxin in grain dust-induced lung disease.

Science.gov (United States)

Schwartz, D A; Thorne, P S; Yagla, S J; Burmeister, L F; Olenchock, S A; Watt, J L; Quinn, T J

1995-08-01

To identify the role of endotoxin in grain dust-induced lung disease, we conducted a population-based, cross-sectional investigation among grain handlers and postal workers. The study subjects were selected by randomly sampling all grain facilities and post offices within 100 miles of Iowa City. Our study population consisted of 410 grain workers and 201 postal workers. Grain workers were found to be exposed to higher concentrations of airborne dust (p = 0.0001) and endotoxin (p = 0.0001) when compared with postal workers. Grain workers had a significantly higher prevalence of work-related (cough, phlegm, wheezing, chest tightness, and dyspnea) and chronic (usual cough or phlegm production) respiratory symptoms than postal workers. Moreover, after controlling for age, gender, and cigarette smoking status, work-related respiratory symptoms were strongly associated with the concentration of endotoxin in the bioaerosol in the work setting. The concentration of total dust in the bioaerosol was marginally related to these respiratory problems. After controlling for age, gender, and cigarette smoking status, grain workers were found to have reduced spirometric measures of airflow (FEV1, FEV1/FVC, and FEF25-75) and enhanced airway reactivity to inhaled histamine when compared with postal workers. Although the total dust concentration in the work environment appeared to have little effect on these measures of airflow obstruction, higher concentrations of endotoxin in the bioaerosol were associated with diminished measures of airflow and enhanced bronchial reactivity. Our results indicate that the concentration of endotoxin in the bioaerosol may be particularly important in the development of grain dust-induced lung disease.

2-methylanthraquinone as a marker of occupational exposure to teak wood dust in boatyards.

Science.gov (United States)

Gori, Giampaolo; Carrieri, Mariella; Scapellato, Maria Luisa; Parvoli, Giorgio; Ferrara, Daniela; Rella, Rocco; Sturaro, Alberto; Bartolucci, Giovanni Battista

2009-01-01

A new gas chromatographic/mass spectrometric (GC/MS) method was developed to detect 2-methylanthraquinone (2-MeA) in wood dust. 2-MeA is present in teak wood (a suspected human carcinogen) but not in oak, beech, mahogany, birch, ash or pine. The method involved collection of workplace dust on filters and extraction of 2-MeA with methanol and GC/MS analysis. The method was tested on teak wood dust samples (n = 43) collected on polyvinylchloride membrane filters during various work operations in four small factories making furniture and fittings for leisure craft and boatyards (air teak wood dust concentration: range 0.32-14.32 mg m(-3)). A high correlation coefficient for the content of 2-MeA versus teak dust was obtained (logarithmic correlation: y = 1.5308x + 0.0998, r = 0.9215). Determination of airborne 2-MeA is a useful technique to confirm occupational exposure to teak wood dust.

Bio-processing of copper from combined smelter dust and flotation concentrate: a comparative study on the stirred tank and airlift reactors.

Science.gov (United States)

Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

2012-11-30

To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu(2)S, CuS, and Cu(5)FeS(4).Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results. Copyright © 2012 Elsevier B.V. All rights reserved.

Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma

Energy Technology Data Exchange (ETDEWEB)

Rahim, Z.; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Center for Physics (NCP) at QAU Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)

2014-07-15

The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, we obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist.

Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma

International Nuclear Information System (INIS)

Rahim, Z.; Qamar, A.; Ali, S.

2014-01-01

The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, we obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist

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

Science.gov (United States)

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

2010-01-01

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

Dust particle removal efficiency of a venturi scrubber

International Nuclear Information System (INIS)

Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Mehboob, Khurram

2013-01-01

Highlights: ► Experimental and theoretical study of dust removal efficiency in venturi scrubber. ► Dust removal efficiency 99.5% is achieved at throat gas velocity 220 m/s. ► Results obtained from mathematical model concur well with experimental results. - Abstract: The venturi scrubber is one of the most efficient gas cleaning devices to remove the contaminated particles from gaseous stream during severe accident in nuclear power plant. This study is focused on the dust particle removal efficiency of the venturi scrubber experimentally and theoretically. The venturi scrubber encapsulates the dust particles in petite water droplets flowing into it. The water injected into the scrubber is in the form of water film. The study investigates the removal efficiency of venturi scrubber for throat gas velocities of 130, 165 and 200 m/s and liquid flow rates 0.3–1 m 3 /h, whereas dust concentration ranges between 0.1 and 1 g/m 3 . The hydrophobic titanium dioxide (TiO 2 ) particles having density 4.23 g/cm 3 and mean diameter of 1 μm are used as dust particles in this research. Filtration technique is used to measure the concentration of dust particles at inlet and outlet. Experimental results show that the removal efficiency is higher with the increase of throat gas velocity and liquid flow rate. A mathematical model is employed for the verification of experimental results. The model concurs well with the experimental results

Magnetic Measurements of Atmospheric Dust Deposition in Soils

Science.gov (United States)

Kapička, Aleš; Petrovský, Eduard; Grison, Hana; Podrázský, Vilém; Křížek, Pavel

2010-05-01

Atmospheric dust of anthropogenic origin contains significant portion of minerals characterized by ferrimagnetic properties [1,2]. These minerals, mostly iron oxides, can serve as tracers of industrial pollutants in soil layers. Moreover, recent results, e.g., [3,4] show significant correlation between concentration-dependent magnetic parameters (e.g., low-field magnetic susceptibility) and concentration of heavy metals (e.g., Pb, Zn, Cd). In our paper we have investigated magnetic properties of depth soil profiles from Krušné hory Mountains (Czech Republic), which belong to a highly contaminated, so-called Black Triangle in central Europe. Emissions are determined by considerable concentration of big sources of pollution (power plants burning fossil fuel, metallurgical and chemical industry). Increased values of magnetic susceptibility (25 - 200 × 10-5 SI) were clearly identified in the top-soil layers. Thermomagnetic analyses and SEM observation indicate that the accumulated anthropogenic ferrimagnetics dominate these layers. Magnetic enhancement is limited to depths of 4-7 cm below the soil surface, usually in F-H or top of Ah soil horizons; deeper soil horizons contain mainly magnetically weak materials and are characterized by much lower values of susceptibility (up to 30 × 10-5 SI). Significant magnetic parameters (e.g., Curie temperature Tc) and SEM results of contaminated topsoils are comparable with magnetic parameters of atmospheric dust, collected (using high-volume samplers) at the same localities.

Associations between brominated flame retardants in house dust and hormone levels in men

International Nuclear Information System (INIS)

Johnson, Paula I.; Stapleton, Heather M.; Mukherjee, Bhramar; Hauser, Russ; Meeker, John D.

2013-01-01

Brominated flame retardants (BFRs) are used in the manufacture of a variety of materials and consumer products in order to meet fire safety standards. BFRs may persist in the environment and have been detected in wildlife, humans and indoor dust and air. Some BFRs have demonstrated endocrine and reproductive effects in animals, but human studies are limited. In this exploratory study, we measured serum hormone levels and flame retardant concentrations [31 polybrominated diphenyl ether (PBDE) congeners and 6 alternate flame retardants] in house dust from men recruited through a US infertility clinic. PBDE congeners in dust were grouped by commercial mixtures (i.e. penta-, octa- and deca-BDE). In multivariable linear regression models adjusted by age and body mass index (BMI), significant positive associations were found between house dust concentrations of pentaBDEs and serum levels of free T4, total T3, estradiol, and sex hormone binding globulin (SHBG), along with an inverse association with follicle stimulating hormone (FSH). There were also positive associations of octaBDE concentrations with serum free T4, thyroid stimulating hormone (TSH), luteinizing hormone (LH) and testosterone and an inverse association of decaBDE concentrations with testosterone. Hexabromocyclododecane (HBCD) was associated with decreased SHBG and increased free androgen index. Dust concentrations of bis-tribromophenoxyethane (BTBPE) and tetrabromo-diethylhexylphthalate (TBPH) were positively associated with total T3. These findings are consistent with our previous report of associations between PBDEs (BDE 47, 99 and 100) in house dust and hormone levels in men, and further suggest that exposure to contaminants in indoor dust may be leading to endocrine disruption in men. - Highlights: ► Brominated flame retardants (BFRs) including PBDEs and alternates were measured. ► Exposure to BFRs is characterized from concentrations in participant vacuum bag dust. ► Exposure to PBDEs and

Associations between brominated flame retardants in house dust and hormone levels in men

Energy Technology Data Exchange (ETDEWEB)

Johnson, Paula I. [Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Stapleton, Heather M. [Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708 (United States); Mukherjee, Bhramar [Department of Biostatistics, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Hauser, Russ [Department of Environmental Health, Harvard School of Public Health, 677 Huntington Ave., Boston, MA 02115 (United States); Meeker, John D., E-mail: meekerj@umich.edu [Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 (United States)

2013-02-15

Brominated flame retardants (BFRs) are used in the manufacture of a variety of materials and consumer products in order to meet fire safety standards. BFRs may persist in the environment and have been detected in wildlife, humans and indoor dust and air. Some BFRs have demonstrated endocrine and reproductive effects in animals, but human studies are limited. In this exploratory study, we measured serum hormone levels and flame retardant concentrations [31 polybrominated diphenyl ether (PBDE) congeners and 6 alternate flame retardants] in house dust from men recruited through a US infertility clinic. PBDE congeners in dust were grouped by commercial mixtures (i.e. penta-, octa- and deca-BDE). In multivariable linear regression models adjusted by age and body mass index (BMI), significant positive associations were found between house dust concentrations of pentaBDEs and serum levels of free T4, total T3, estradiol, and sex hormone binding globulin (SHBG), along with an inverse association with follicle stimulating hormone (FSH). There were also positive associations of octaBDE concentrations with serum free T4, thyroid stimulating hormone (TSH), luteinizing hormone (LH) and testosterone and an inverse association of decaBDE concentrations with testosterone. Hexabromocyclododecane (HBCD) was associated with decreased SHBG and increased free androgen index. Dust concentrations of bis-tribromophenoxyethane (BTBPE) and tetrabromo-diethylhexylphthalate (TBPH) were positively associated with total T3. These findings are consistent with our previous report of associations between PBDEs (BDE 47, 99 and 100) in house dust and hormone levels in men, and further suggest that exposure to contaminants in indoor dust may be leading to endocrine disruption in men. - Highlights: ► Brominated flame retardants (BFRs) including PBDEs and alternates were measured. ► Exposure to BFRs is characterized from concentrations in participant vacuum bag dust. ► Exposure to PBDEs and

Regularities of dust formation during stone cutting for construction works

Directory of Open Access Journals (Sweden)

V.G. Lebedev

2016-09-01

Full Text Available When cutting stone, a large amount of dust release, which is a mixture of small, mostly sharp, mineral particles. Shallow dry dust with inhalation causes the pathological changes in organs that are a consequence of infiltration of acute and solids particles. Despite the importance of this problem, the questions of dust generation during the various working processes and its fractions distribution are practically not considered. This determines the time of dust standing in the air and its negative impact on a person. Aim: The aim of this research is to study the process of dusting during stones cutting and dust distribution on fractions regularities and quantification of dust formation process in order to improve the production equipment, staff individual and collective safety equipment. Materials and Methods: Many types of cutting can be divided into two types - a “dry” cutting and cutting with fluid. During “dry” cutting a dust represents a set of micro-chips which are cut off by the abrasive grains. The size of such chips very small: from a micrometer to a few micrometers fraction. Thus, the size of chips causes the possibility of creating dust slurry with low fall velocity, and which is located in the working space in large concentrations. Results: The following characteristic dependences were obtained as a result of research: dependence of the dust fall from the size of the dust particles, size of dust particles from minute feeding and grain range wheel, the specific amount of dust from the number of grit abrasive wheel and the temperature of the dust particles from the feeding at wheel turnover. It was shown that the distribution of chips (dust by size will request of a normal distribution low. Dimensions of chips during cut are in the range of 0.4...6 μm. Thus, dust slurry is formed with time of particles fall of several hours. This creates considerable minute dust concentration - within 0.28∙10^8...1.68∙10^8 units/m3.

Recently deglaciated high-altitude soils of the Himalaya: diverse environments, heterogenous bacterial communities and long-range dust inputs from the upper troposphere.

Directory of Open Access Journals (Sweden)

Blaz Stres

Full Text Available The Himalaya with its altitude and geographical position forms a barrier to atmospheric transport, which produces much aqueous-particle monsoon precipitation and makes it the largest continuous ice-covered area outside polar regions. There is a paucity of data on high-altitude microbial communities, their native environments and responses to environmental-spatial variables relative to seasonal and deglaciation events.Soils were sampled along altitude transects from 5000 m to 6000 m to determine environmental, spatial and seasonal factors structuring bacterial communities characterized by 16 S rRNA gene deep sequencing. Dust traps and fresh-snow samples were used to assess dust abundance and viability, community structure and abundance of dust associated microbial communities. Significantly different habitats among the altitude-transect samples corresponded to both phylogenetically distant and closely-related communities at distances as short as 50 m showing high community spatial divergence. High within-group variability that was related to an order of magnitude higher dust deposition obscured seasonal and temporal rearrangements in microbial communities. Although dust particle and associated cell deposition rates were highly correlated, seasonal dust communities of bacteria were distinct and differed significantly from recipient soil communities. Analysis of closest relatives to dust OTUs, HYSPLIT back-calculation of airmass trajectories and small dust particle size (4-12 µm suggested that the deposited dust and microbes came from distant continental, lacustrine and marine sources, e.g. Sahara, India, Caspian Sea and Tibetan plateau. Cyanobacteria represented less than 0.5% of microbial communities suggesting that the microbial communities benefitted from (codeposited carbon which was reflected in the psychrotolerant nature of dust-particle associated bacteria.The spatial, environmental and temporal complexity of the high-altitude soils of the

Recently deglaciated high-altitude soils of the Himalaya: diverse environments, heterogenous bacterial communities and long-range dust inputs from the upper troposphere.

Science.gov (United States)

Stres, Blaz; Sul, Woo Jun; Murovec, Bostjan; Tiedje, James M

2013-01-01

The Himalaya with its altitude and geographical position forms a barrier to atmospheric transport, which produces much aqueous-particle monsoon precipitation and makes it the largest continuous ice-covered area outside polar regions. There is a paucity of data on high-altitude microbial communities, their native environments and responses to environmental-spatial variables relative to seasonal and deglaciation events. Soils were sampled along altitude transects from 5000 m to 6000 m to determine environmental, spatial and seasonal factors structuring bacterial communities characterized by 16 S rRNA gene deep sequencing. Dust traps and fresh-snow samples were used to assess dust abundance and viability, community structure and abundance of dust associated microbial communities. Significantly different habitats among the altitude-transect samples corresponded to both phylogenetically distant and closely-related communities at distances as short as 50 m showing high community spatial divergence. High within-group variability that was related to an order of magnitude higher dust deposition obscured seasonal and temporal rearrangements in microbial communities. Although dust particle and associated cell deposition rates were highly correlated, seasonal dust communities of bacteria were distinct and differed significantly from recipient soil communities. Analysis of closest relatives to dust OTUs, HYSPLIT back-calculation of airmass trajectories and small dust particle size (4-12 µm) suggested that the deposited dust and microbes came from distant continental, lacustrine and marine sources, e.g. Sahara, India, Caspian Sea and Tibetan plateau. Cyanobacteria represented less than 0.5% of microbial communities suggesting that the microbial communities benefitted from (co)deposited carbon which was reflected in the psychrotolerant nature of dust-particle associated bacteria. The spatial, environmental and temporal complexity of the high-altitude soils of the Himalaya

Impact of Dust on Air Quality and Radiative Forcing : AN Episodic Study for the Megacity Istanbul Using RegCM4.1

Science.gov (United States)

Agacayak, T.; Kindap, T.; Unal, A.; Mallet, M.; Pozzoli, L.; Karaca, M.; Solmon, F.

2012-04-01

Istanbul is a megacity (with population over 15 million) that has significant levels of Particulate Matter concentrations. It is suspected that long-range transport of Saharan dust is one of the main contributors. The purpose of this study is to investigate the relationship between high PM concentrations and dust transport using atmospheric modeling, satellite data as well as in-situ observations. Measurements of PM10 concentrations at 10 different stations in Istanbul for the period 2004-2010 were provided by the Turkish Ministry of Environment. Daily mean PM10 concentrations exceeding the European standard of 50 µg/m3 were found to be, on average, 49 days for the Spring period, 45 days for the Winter period, and 41 days for the Fall period. DREAM model output (Nickovic et al. 2001; Perez et al. 2006) suggests that high PM10 concentrations correlate highly with mineral dust transport episodes from Saharan desert (i.e., 23% for winter and 58% for spring). In this study, we have utilized RegCM4.1 model to further investigate the Saharan dust transport in the selected episodes. During the period between March 21st and 24th, 2008, observed daily mean of PM10 concentrations reach up to 140 µg/m3 in Istanbul. Simulations conducted by RegCM4.1 provides AOD (350-640 nm model band) values ranging between 0.04 and 0.98during this episode. Central Anatolia is affected from the dust transport on 21 and 22 March 2008, with a daily mean AOD of 0.9. On 23th March 2008, the dust plume reaches the Marmara Sea and AOD increases about 1.0 over the region according to both DREAM and RegCM4.1 model outputs. On the fourth day of the episode, the dust event stops and AOD decreases to 0.5 over the region. Asymmetry parameters can be seen as 0.62 during the dust episode, while single scattering albedo is about 0.93 during the entire dust episode over Istanbul. The effect of the dust episode on the regional radiative budget over Istanbul was also estimated. Model results indicate a daily

Long-term dust climatology in the western United States reconstructed from routine aerosol ground monitoring

Directory of Open Access Journals (Sweden)

D. Q. Tong

2012-06-01

Full Text Available This study introduces an observation-based dust identification approach and applies it to reconstruct long-term dust climatology in the western United States. Long-term dust climatology is important for quantifying the effects of atmospheric aerosols on regional and global climate. Although many routine aerosol monitoring networks exist, it is often difficult to obtain dust records from these networks, because these monitors are either deployed far away from dust active regions (most likely collocated with dense population or contaminated by anthropogenic sources and other natural sources, such as wildfires and vegetation detritus. Here we propose an approach to identify local dust events relying solely on aerosol mass and composition from general-purpose aerosol measurements. Through analyzing the chemical and physical characteristics of aerosol observations during satellite-detected dust episodes, we select five indicators to be used to identify local dust records: (1 high PM₁₀ concentrations; (2 low PM_2.5/PM₁₀ ratio; (3 higher concentrations and percentage of crustal elements; (4 lower percentage of anthropogenic pollutants; and (5 low enrichment factors of anthropogenic elements. After establishing these identification criteria, we conduct hierarchical cluster analysis for all validated aerosol measurement data over 68 IMPROVE sites in the western United States. A total of 182 local dust events were identified over 30 of the 68 locations from 2000 to 2007. These locations are either close to the four US Deserts, namely the Great Basin Desert, the Mojave Desert, the Sonoran Desert, and the Chihuahuan Desert, or in the high wind power region (Colorado. During the eight-year study period, the total number of dust events displays an interesting four-year activity cycle (one in 2000–2003 and the other in 2004–2007. The years of 2003, 2002 and 2007 are the three most active dust periods, with 46, 31 and 24

Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

KAUST Repository

Bangalath, Hamza Kunhu; Stenchikov, Georgiy L.

2015-01-01

Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL's High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

Experimental coal dust suppression system installed at the Nikola Tesla thermal power plant

Energy Technology Data Exchange (ETDEWEB)

Guzijan, D [Rudarski Institut, Belgrade (Yugoslavia). Zavod za Ventilaciju i Tehnicku Zastitu

1988-01-01

Describes a project conducted at the Nikola Tesla thermal power plant by the Mining Institute of Belgrade to reduce the high levels of dust concentrations in overloading stations on coal conveyors and hoppers. A mathematical model was developed to determine the ventilation capacity required at each of the 18 overloading stations with the hoppers considered successively: empty, 1/3 full, 2/3 full and completely full. Shows how this model enabled an efficient dust suppression system to be developed and subsequently installed by the Termovent company in Belgrade using 4 axial ventilators supplied by the Ventilator Company in Zagreb. The ventilators were powered by means of 5.5 kW electric motors and provided 440 Pa pressure at 950 rpm. Gives the result of dust concentration measurements indicating that the installed system achieved the results predicted by the mathematical model and that the levels were well below the statutory limit. A description of the complete installation is included. 3 refs.

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

International Nuclear Information System (INIS)

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

2009-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2009-05-15

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

Mineral Dust Instantaneous Radiative Forcing in the Arctic

Science.gov (United States)

Kylling, A.; Groot Zwaaftink, C. D.; Stohl, A.

2018-05-01

Mineral dust sources at high and low latitudes contribute to atmospheric dust loads and dust deposition in the Arctic. With dust load estimates from Groot Zwaaftink et al. (https://doi.org/10.1002/2016JD025482), we quantify the mineral dust instantaneous radiative forcing (IRF) in the Arctic for the year 2012. The annual-mean top of the atmosphere IRF is 0.225 W/m2, with the largest contributions from dust transported from Asia south of 60°N and Africa. High-latitude (>60°N) dust sources contribute about 39% to top of the atmosphere IRF and have a larger impact (1 to 2 orders of magnitude) on IRF per emitted kilogram of dust than low-latitude sources. Mineral dust deposited on snow accounts for nearly all of the bottom of the atmosphere IRF of 0.135 W/m2. More than half of the bottom of the atmosphere IRF is caused by dust from high-latitude sources, indicating substantial regional climate impacts rarely accounted for in current climate models.

Farmers' exposure to dusts and gases in modern Finnish cubicle cow houses

Directory of Open Access Journals (Sweden)

K. LOUHELAINEN

2008-12-01

Full Text Available The occurrence of airborne dust, gases, microbes, endotoxin and bovine epithelial antigens (BEA, BDA20 was studied in 26 modern, mainly cubicle, cow houses. Air samples of total dust, total spores, endotoxin and bovine epithelial allergens were collected on membrane filters with portable or piston pumps and analyzed with appropriate methods. Concentrations of gases (ammonia, carbon dioxide, hydrogen sulfide were measured with diffusion tubes. Airborne viable spores were collected with a cascade impactor on five selective culture media for the identification of xerophilic, mesophilic and thermotolerant fungi and thermophilic actinomycetes. The geometric mean concentrations of total dust, BEA and BDA20 were 0.2-1.9 mg/m 3 , 5.2- 9.7 mg/m 3 and 50-260 ng/m 3 , respectively. The mean concentrations of ammonia and carbon dioxide were between 2.8-15 ppm and 2200-3200 ppm, respectively. The geometric mean of endotoxins was 19 ng/m 3 and the concentrations of fungi were at the 10 1 -10 3 cfu/m 3 level. In general, the variation in concentrations of total dust, viable fungi and endotoxin was large. The concentrations of total dust and fungi were lower than in earlier studies. Thus new cubicle houses provide a better working environment with regard to airborne hazards than the traditional cow houses.;

CV-Dust: Atmospheric aerosol in the Cape Verde region: carbon and soluble fractions of PM10

Science.gov (United States)

Pio, C.; Nunes, T.; Cardoso, J.; Caseiro, A.; Custódio, D.; Cerqueira, M.; Patoilo, D.; Almeida, S. M.; Freitas, M. C.

2012-04-01

than 100 PM10 samples, addressing mainly their mass concentrations and the chemical composition of water soluble ions and carbon species (carbonates and organic and elemental carbon). Different PM10 samplers worked simultaneously in order to collect enough mass to make the aerosol characterization through the different methodologies and to collect aerosols in different filter matrixes, which have to be appropriated to the chemical and mineralogical analysis. The sampling site was located at Santiago Island, in the surroundings of Praia City (14° 55' N e 23° 29' W, 98 m at sea level). High concentrations, up to more than 400 μg m-3, are connected to north-east and north-northeast winds, and it was identified several dust events characteristic of "bruma seca", whose duration is on average of two to four days. Backward trajectories analysis confirms that the high concentrations in Cape Verde are associated with air masses passing over the Sahara. During dust events the percentage of inorganic water soluble ions for the total PM10 mass concentration decreased significantly to values lower than 10% in comparison with remainder data that range around 45±10%. Acknowledgement: This work was funded by the Portuguese Science Foundation (FCT) through the project PTDD/AAC-CLI/100331/2008 and FCOMP-01-0124-FEDER-008646 (CV-Dust). J. Cardoso acknowledges the PhD grant SFRH-BD-6105-2009 from FCT.

30 CFR 71.100 - Respirable dust standard.

Science.gov (United States)

2010-07-01

... concentration of respirable dust in the mine atmosphere during each shift to which each miner in the active... shall be measured with an approved sampling device and expressed in terms of an equivalent concentration determined in accordance with § 71.206 (Approved sampling devices; equivalent concentrations). ...

Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season

International Nuclear Information System (INIS)

Prasad, Anup K.; El-Askary, Hesham; Kafatos, Menas

2010-01-01

The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe. - New evidence of desert dust transport from Western Sahara to Nile Delta during black cloud season and its significance for regional aerosols, dust models, and potential impact on the regional climate.

Implications of high altitude desert dust transport from Western Sahara to Nile Delta during biomass burning season

Energy Technology Data Exchange (ETDEWEB)

Prasad, Anup K., E-mail: aprasad@chapman.ed [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States); El-Askary, Hesham [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States); Department of Environmental Sciences, Faculty of Science, Alexandria University, Moharem Bek, Alexandria 21522 (Egypt); National Authority for Remote Sensing and Space Science (NARSS), Cairo (Egypt); Kafatos, Menas [School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Center of Excellence in Earth Observing, Chapman University, Orange, CA 92866 (United States)

2010-11-15

The air over major cities and rural regions of the Nile Delta is highly polluted during autumn which is the biomass burning season, locally known as black cloud. Previous studies have attributed the increased pollution levels during the black cloud season to the biomass or open burning of agricultural waste, vehicular, industrial emissions, and secondary aerosols. However, new multi-sensor observations (column and vertical profiles) from satellites, dust transport models and associated meteorology present a different picture of the autumn pollution. Here we show, for the first time, the evidence of long range transport of dust at high altitude (2.5-6 km) from Western Sahara and its deposition over the Nile Delta region unlike current Models. The desert dust is found to be a major contributor to the local air quality which was previously considered to be due to pollution from biomass burning enhanced by the dominant northerly winds coming from Europe. - New evidence of desert dust transport from Western Sahara to Nile Delta during black cloud season and its significance for regional aerosols, dust models, and potential impact on the regional climate.

Star Formation in High Pressure, High Energy Density Environments: Laboratory Experiments of ISM Dust Analogs

International Nuclear Information System (INIS)

Breugel, W. van; Bajt, S.; Bradley, J.; Bringa, E.; Dai, Z.; Felter, T.; Graham, G.; Kucheyev, S.; Torres, D.; Tielens, A.; Baragiola, R.; Dukes, C.; Loeffler, M.

2005-01-01

Dust grains control the chemistry and cooling, and thus the gravitational collapse of interstellar clouds. Energetic particles, shocks and ionizing radiation can have a profound influence on the structure, lifetime and chemical reactivity of the dust, and therefore on the star formation efficiency. This would be especially important in forming galaxies, which exhibit powerful starburst (supernovae) and AGN (active galactic nucleus) activity. How dust properties are affected in such environments may be crucial for a proper understanding of galaxy formation and evolution. The authors present the results of experiments at LLNL which show that irradiation of the interstellar medium (ISM) dust analog forsterite (Mg 2 SiO 4 ) with swift heavy ions (10 MeV Xe) and a large electronic energy deposition amorphizes its crystalline structure, without changing its chemical composition. From the data they predict that silicate grains in the ISM, even in dense and cold giant molecular clouds, can be amorphized by heavy cosmic rays (CR's). This might provide an explanation for the observed absence of crystalline dust in the ISM clouds of the Milky Way galaxy. This processing of dust by CR's would be even more important in forming galaxies and galaxies with active black holes

Surface observation of sand and dust storm in East Asia and its application in CUACE/Dust

Directory of Open Access Journals (Sweden)

Y. Q. Wang

2008-02-01

Full Text Available The spatial-temporal distributions and sources of sand and dust storm (SDS in East Asia from 2001 to 2006 were investigated on the basis of visibility and PM₁₀ data from the routine SDS and weather monitoring networks run by CMA (China Meteorological Administration. A power functional relationships between PM₁₀ and visibility was found among various regions generally with a good correlation (r²=0.90, especially in Asian SDS source regions. In addition, three SDS occurrence centers, i.e. western China, Mongolia and northern China, were identified with the Mongolia source contributing more dust to the downwind areas including Korea and Japan than other two sources. Generally, high PM₁₀ concentrations were observed in most areas of northern China. The highest value was obtained in the center of western China with a spring daily mean value of 876 μgm⁻³, and the value in other source regions exceeds 200 μgm⁻³. These data sets together with the satellite observations in China form the main observation database for the evaluation and data assimilation of CUACE/Dust system – an operational SDS forecasting system for East Asia.

High-resolution regional modeling of summertime transport and impact of African dust over the Red Sea and Arabian Peninsula

KAUST Repository

Kalenderski, Stoitchko Dimitrov

2016-05-23

Severe dust outbreaks and high dust loading over Eastern Africa and the Red Sea are frequently detected in the summer season. Observations suggest that small-scale dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand these processes, we present here the first high resolution modeling study of a dust outbreak in June 2012 developed over East Africa, the Red Sea, and the Arabian Peninsula. Using the Weather Research and Forecasting model coupled with Chemistry component (WRF-Chem), we identified several dust generating dynamical processes that range from convective to synoptic scales, including synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea, most of the dust transport occurs above 2 km height, whereas across the central and southern parts of the sea, dust is mostly transported below 2 km height. Dust is the dominant contributor (87%) to the aerosol optical depth, producing a domain average cooling effect of -12.1 W m-2 at the surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. Both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. Model results compare well with available ground-based and satellite observations, but generally underestimate the observed maximum values of aerosol optical depth. The satellite-retrieved mean optical depth at some locations are underestimated by a factor of two. A sensitive experiment suggests that these large local differences may result from poor characterization of dust emissions in some areas of the modeled domain. In this case study we successfully simulate the major fine-scale dust generating dynamical processes, explicitly resolving convection and haboob

Respirable dust measured downwind during rock dust application.

Science.gov (United States)

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

2017-05-01

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

Endotoxins in indoor air and settled dust in primary schools in a subtropical climate.

Science.gov (United States)

Salonen, Heidi; Duchaine, Caroline; Létourneau, Valérie; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

2013-09-03

Endotoxins can significantly affect the air quality in school environments. However, there is currently no reliable method for the measurement of endotoxins, and there is a lack of reference values for endotoxin concentrations to aid in the interpretation of measurement results in school settings. We benchmarked the "baseline" range of endotoxin concentration in indoor air, together with endotoxin load in floor dust, and evaluated the correlation between endotoxin levels in indoor air and settled dust, as well as the effects of temperature and humidity on these levels in subtropical school settings. Bayesian hierarchical modeling indicated that the concentration in indoor air and the load in floor dust were generally (EU/m(3) and EU/m(2), respectively. Exceeding these levels would indicate abnormal sources of endotoxins in the school environment and the need for further investigation. Metaregression indicated no relationship between endotoxin concentration and load, which points to the necessity for measuring endotoxin levels in both the air and settled dust. Temperature increases were associated with lower concentrations in indoor air and higher loads in floor dust. Higher levels of humidity may be associated with lower airborne endotoxin concentrations.

Influence of fly dust from coking plants on some biological processes of plants

Energy Technology Data Exchange (ETDEWEB)

Masek, V

1972-03-01

The influence of three typical samples of fly dust from a coking plant on enzymatic reactions, photosynthesis, chlorophyll concentration in leaves of bean plants was studied. The hydrolysis of starch with amylases and of the albumen with pepsin at 37 C and the inversion of sacharosis by invertase in a buffered environment were also examined. None of the three dust samples had a significant effect on enzymatic reactions. Applying the dust samples to the leaves of young bean plants reduced the intensity of photosynthesis and chlorophyll concentration. In aqueous extracts, the dust samples liberated only small quantities of nutrients, plants which were grown in a dust suspension showed no increase of dry substance and growth rate. A stimulating effect of the dust samples on root growth was determined. Mixing the dust samples with the soil influenced the accessibility of water to plants. 17 references, 6 figures, 9 tables.

Comparison of a direct-reading device to gravimetric methods for evaluating organic dust aerosols in an enclosed swine production environment.

Science.gov (United States)

Taylor, C D; Reynolds, S J

2001-01-01

The production of livestock in enclosed facilities has become an accepted practice, driven by the need for increased efficiency. Exposure to organic dusts, containing various bioactive components, has been identified an important risk factor for the high rate of lung disease found among workers in these environments. Assessment of organic dust exposure requires technical skills and instrumentation not readily available to most agricultural enterprises. Development of a simple, cost-effective method for measuring organic dust levels would be useful in evaluating and controlling exposures in these environments. The objective of this study was to evaluate the usefulness of the direct reading MIE PDM-3 Miniram for estimating organic dust concentrations in enclosed swine production facilities. Responses from the MIE PDM-3 Miniram were compared to gravimetric methods for total and inhalable dust. Total dust determinations were conducted in accordance with the National Institute for Occupational Safety and Health (NIOSH) method 0500. Inhalable particulate mass (IPM) sampling was conducted using SKC brand IOM (Institute of Occupational Medicine) sampling cassettes, which meet the American Conference of Governmental Industrial Hygienists ACGIH criteria for inhalable dust sampling. This study design also allowed for the comparison of traditional total dust method to the IPM method, in collecting organic dusts in an agricultural setting. Fifteen sets of side-by-side samples (Miniram, total dust, and IPM) were collected over a period of six months in a swine confinement building. There were statistically significant differences in the results provided by the three sampling methods. Measurements for inhalable dust exceeded those for total dust in eleven of fifteen samples. The Miniram time-weighted average (TWA) response to the organic dust was always the lower of the three methods. A high degree of correlation was found among all three methods. The Miniram performed well under

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Sensitivity of tropical rainbelt over Africa and Middle East to dust shortwave absorption: Experiments using a high resolution AGCM

KAUST Repository

Bangalath, Hamza Kunhu

2015-04-01

Response of the rainbelt over Africa to dust direct radiative forcing has been an area of lively debate and is a subject of ongoing research. Previous modeling studies have contrasting results producing different amplitudes or even signs of responses. Uncertainties in the dust radiative forcing are thought to be the major cause of discrepancies in the simulated responses among various studies. The imaginary part of mineral dust shortwave refractive index, which defines the dust absorptivity, has a wide range of values estimated from various observational and modeling studies, as it depends on dust chemical composition and mineralogy. Balkanski et al. (2007) estimated dust shortwave refractive indices by assuming 3 different hematite contents, 0.9%, 1.5% and 2.7% by volume, which corresponds to inefficient, standard, and very efficient dust shortwave absorption, respectively. To investigate the sensitivity of the position and intensity of the tropical rainbelt over Africa and its extension to the Arabian Peninsula to dust shortwave absorption, we have conducted ensembles of numerical simulations for each of the three dust absorptivity scenarios using a high resolution Atmospheric General Circulation Model (AGCM), GFDL\\'s High Resolution Atmospheric Model (HiRAM), at a spatial resolution of 25 km. We found that the strength and the latitudinal extent of the rainbelt are very sensitive to dust shortwave absorption, as well as circulations at various spatiotemporal scales that drive the climate of the region. Reference: Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81 - 95.

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

Science.gov (United States)

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

2010-01-01

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

Cometary dust: the diversity of primitive refractory grains.

Science.gov (United States)

Wooden, D H; Ishii, H A; Zolensky, M E

2017-07-13

Comet dust is primitive and shows significant diversity. Our knowledge of the properties of primitive cometary particles has expanded significantly through microscale investigations of cosmic dust samples (anhydrous interplanetary dust particles (IDPs), chondritic porous (CP) IDPs and UltraCarbonaceous Antarctic micrometeorites, Stardust and Rosetta ), as well as through remote sensing ( Spitzer IR spectroscopy). Comet dust are aggregate particles of materials unequilibrated at submicrometre scales. We discuss the properties and processes experienced by primitive matter in comets. Primitive particles exhibit a diverse range of: structure and typology; distribution of constituents; concentration and form of carbonaceous and refractory organic matter; Mg- and Fe-contents of the silicate minerals; sulfides; existence/abundance of type II chondrule fragments; high-temperature calcium-aluminium inclusions and ameboid-olivine aggregates; and rarely occurring Mg-carbonates and magnetite, whose explanation requires aqueous alteration on parent bodies. The properties of refractory materials imply there were disc processes that resulted in different comets having particular selections of primitive materials. The diversity of primitive particles has implications for the diversity of materials in the protoplanetary disc present at the time and in the region where the comets formed.This article is part of the themed issue 'Cometary science after Rosetta'. © 2017 The Authors.

The Lunar Dust Environment

Science.gov (United States)

Szalay, Jamey Robert

Planetary bodies throughout the solar system are continually bombarded by dust particles, largely originating from cometary activities and asteroidal collisions. Surfaces of bodies with thick atmospheres, such as Venus, Earth, Mars and Titan are mostly protected from incoming dust impacts as these particles ablate in their atmospheres as 'shooting stars'. However, the majority of bodies in the solar system have no appreciable atmosphere and their surfaces are directly exposed to the flux of high speed dust grains. Impacts onto solid surfaces in space generate charged and neutral gas clouds, as well as solid secondary ejecta dust particles. Gravitationally bound ejecta clouds forming dust exospheres were recognized by in situ dust instruments around the icy moons of Jupiter and Saturn, and had not yet been observed near bodies with refractory regolith surfaces before NASA's Lunar Dust and Environment Explorer (LADEE) mission. In this thesis, we first present the measurements taken by the Lunar Dust Explorer (LDEX), aboard LADEE, which discovered a permanently present, asymmetric dust cloud surrounding the Moon. The global characteristics of the lunar dust cloud are discussed as a function of a variety of variables such as altitude, solar longitude, local time, and lunar phase. These results are compared with models for lunar dust cloud generation. Second, we present an analysis of the groupings of impacts measured by LDEX, which represent detections of dense ejecta plumes above the lunar surface. These measurements are put in the context of understanding the response of the lunar surface to meteoroid bombardment and how to use other airless bodies in the solar system as detectors for their local meteoroid environment. Third, we present the first in-situ dust measurements taken over the lunar sunrise terminator. Having found no excess of small grains in this region, we discuss its implications for the putative population of electrostatically lofted dust.

High-Fidelity Lunar Dust Simulant, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The severity of the lunar dust problems encountered during the Apollo missions were consistently underestimated by ground tests, illustrating the need to develop...

High-Fidelity Lunar Dust Simulant, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The severity of the lunar dust problems encountered during the Apollo missions were consistently underestimated by ground tests, illustrating the need to develop...

Temporal Relationships Between African Dust and Chlorophyll-a in the Eastern Caribbean Basin

Science.gov (United States)

Gomez-Andujar, N. X.; Mayol-Bracero, O. L.; Torres-Delgado, E.

2017-12-01

Seasonal African Dust (AD) transports soluble iron to oligotrophic Caribbean waters, and when bioavailable, it could increase marine primary productivity (PP). Recently, the region has experienced the proliferation of unusually high quantities of Sargassum, an iron-absorbing macroalgae inhabiting the air-sea interface, which possess ecological and economic challenges and whose driving factors are still uncertain. AD events reach Puerto Rico (PR) mostly during boreal summer months. This is also the season when chlorophyll-α (CHL) concentrations are highest, when the algae starts to bloom, and when sediment plumes from the Orinoco River (ORP) also reach nutrient discharge maxima.This study seeks to better understand the temporal relationships between increases in chlorophyll-α and the presence of african dust events in the region. Aerosol data collected at the Cabezas de San Juan Atmospheric Observatory was used to identify AD events between January 2005 and December 2015. Light scattering coefficients were measured with an integrating Nephelometer, while light absorption coefficients were obtained from either the Particle Soot/Absorption Photometer (PSAP) or the Continuous Light Absorption Photometer (CLAP). Spectral properties suggesting AD events were cross-referenced with surface dust concentration image models and source-attributed air masses corresponding to dusty periods using Hybrid Single-Particle Lagrangian Integrated Trajectories (HYSPLIT). For all years with spectral data, modeled monthly wet dust deposition was correlated (r=0.64) with mean CHL concentrations from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS). Daily dust mass column densities from NASA's MERRA-2 model were also correlated (r2= 0.53) to sea surface iron concentrations from NASA's Ocean Biogeochemical Model. We present the 2010 case study, which coincides with the start of the Sargassum bloom and shows CHL peaks occurring a month before ORPs but during the AD season

Characterization of atmospheric bioaerosols along the transport pathway of Asian dust during the Dust-Bioaerosol 2016 Campaign

Science.gov (United States)

Tang, Kai; Huang, Zhongwei; Huang, Jianping; Maki, Teruya; Zhang, Shuang; Shimizu, Atsushi; Ma, Xiaojun; Shi, Jinsen; Bi, Jianrong; Zhou, Tian; Wang, Guoyin; Zhang, Lei

2018-05-01

Previous studies have shown that bioaerosols are injected into the atmosphere during dust events. These bioaerosols may affect leeward ecosystems, human health, and agricultural productivity and may even induce climate change. However, bioaerosol dynamics have rarely been investigated along the transport pathway of Asian dust, especially in China where dust events affect huge areas and massive numbers of people. Given this situation, the Dust-Bioaerosol (DuBi) Campaign was carried out over northern China, and the effects of dust events on the amount and diversity of bioaerosols were investigated. The results indicate that the number of bacteria showed remarkable increases during the dust events, and the diversity of the bacterial communities also increased significantly, as determined by means of microscopic observations with 4,6-diamidino-2-phenylindole (DAPI) staining and MiSeq sequencing analysis. These results indicate that dust clouds can carry many bacteria of various types into downwind regions and may have potentially important impacts on ecological environments and climate change. The abundances of DAPI-stained bacteria in the dust samples were 1 to 2 orders of magnitude greater than those in the non-dust samples and reached 105-106 particles m-3. Moreover, the concentration ratios of DAPI-stained bacteria to yellow fluorescent particles increased from 5.1 % ± 6.3 % (non-dust samples) to 9.8 % ± 6.3 % (dust samples). A beta diversity analysis of the bacterial communities demonstrated the distinct clustering of separate prokaryotic communities in the dust and non-dust samples. Actinobacteria, Bacteroidetes, and Proteobacteria remained the dominant phyla in all samples. As for Erenhot, the relative abundances of Acidobacteria and Chloroflexi had a remarkable rise in dust events. In contrast, the relative abundances of Acidobacteria and Chloroflexi in non-dust samples of R-DzToUb were greater than those in dust samples. Alphaproteobacteria made the major

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

Directory of Open Access Journals (Sweden)

Whitehead Todd P

2012-03-01

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

Mechanisms of metal dusting corrosion

DEFF Research Database (Denmark)

Hummelshøj, Thomas Strabo

In this thesis the early stages of metal dusting corrosion is addressed; the development of carbon expanded austenite, C, and the decomposition hereof into carbides. Later stages of metal dusting corrosion are explored by a systematic study of stainless steel foils exposed to metal dusting...... deformed stainless steel flakes is transformed to expanded martensite/austenite during low-temperature carburization. Various experimental procedures to experimentally determine the concentration dependent diffusion coefficient of carbon in expanded austenite are evaluated. The most promising procedure...... powders and flakes. The nature of the decomposition products, carbides of the form M23C6 and M7C3, were evaluated by X-ray diffraction, light optical microscopy, scanning electron microscopy and thermodynamic modelling. The decomposition was found to be dependent on several parameters such as thermal...

Pulmonary Toxicity Studies of Lunar Dust in Rodents

Science.gov (United States)

Lam, Chiu-Wing; James, John T.

2012-01-01

NASA has been contemplating returning astronauts to the moon for long-duration habitation and research and using it as a stepping-stone to Mars. Other spacefaring nations are planning to send humans to the moon for the first time. The surface of the moon is covered by a layer of fine dust. Fine terrestrial dusts, if inhaled, are known to pose a health risk to humans. Some Apollo crews briefly exposed to moon dust that adhered to spacesuits and became airborne in the Lunar Module reported eye and throat irritation. The habitable area of any lunar landing vehicle or outpost would inevitably become contaminated with lunar dust. To assess the health risks of exposure of humans to airborne lunar dust, we evaluated the toxicity of Apollo 14 moon dust in animal lungs. Studies of the pulmonary toxicity of a dust are generally first done by intratracheal instillation (ITI) of aqueous suspensions of the test dust into the lungs of rodents. If a test dust is irritating or cytotoxic to the lungs, the alveolar macrophages, after phagocytizing the dust particles, will release cellular messengers to recruit white blood cells (WBCs) and to induce dilation of blood capillary walls to make them porous, allowing the WBCs to gain access to the alveolar space. The dilation of capillary walls also allows serum proteins and water entering the lung. Besides altering capillary integrity, a toxic dust can also directly kill the cells that come into contact with it or ingest it, after which the dead cells would release their contents, including lactate dehydrogenase (a common enzyme marker of cell death or tissue damage). In the treated animals, we lavaged the lungs 1 and 4 weeks after the dust instillation and measured the concentrations of these biomarkers of toxicity in the bronchioalveolar lavage fluids to determine the toxicity of the dust. To assess whether the inflammation and cellular injury observed in the biomarker study would lead to persistent or progressive histopathological

Occurrence, distribution and risk of organophosphate esters in urban road dust in Beijing, China.

Science.gov (United States)

Li, Wenhui; Shi, Yali; Gao, Lihong; Wu, Chuandong; Liu, Jiemin; Cai, Yaqi

2018-06-06

As a major group of plasticizers and flame-retardants, organophosphate esters (OPEs) have attracted particular attention due to their wide occurrence and potential impacts on human health and ecosystems. In the present study, the occurrence and distribution of 14 OPEs, including seven Alkyl-OPEs, three Cl-OPEs, and four Aryl-OPEs, were investigated in 65 road dust samples collected from November to December 2014 in Beijing, China. Cl-OPEs were the predominant compounds in the road dust samples, with the median concentration of 646 μg/kg, followed by the Alkyl-OPEs (median 135 μg/kg) and Aryl-OPEs (median 129 μg/kg). Tris(2-chloro-1-methylethyl) phosphate (TCPP) was the most abundant OPE with the median concentration of 384 μg/kg. In addition, OPEs levels showed significant difference (p road with heavy traffic and high population density, indicating that the traffic and population were important factors for this distribution pattern. It was further supported by the analysis of OPEs in roadside soil and indoor dust in the vicinity of road dust sample sites. Finally, the average daily dose (ADD) for OPEs via inhalation, dermal absorption, and ingestion was calculated to evaluate the carcinogenic and non-carcinogenic risks to residents exposed to OPEs in the road dust. Risk assessment revealed that the risk originating from exposure to OPEs of road dust is currently low in Beijing, China. Copyright © 2018 Elsevier Ltd. All rights reserved.

Implementation of dust emission and chemistry into the Community Multiscale Air Quality modeling system and initial application to an Asian dust storm episode

Directory of Open Access Journals (Sweden)

K. Wang

2012-11-01

Full Text Available The US Environmental Protection Agency's (EPA Community Multiscale Air Quality (CMAQ modeling system version 4.7 is further developed to enhance its capability in simulating the photochemical cycles in the presence of dust particles. The new model treatments implemented in CMAQ v4.7 in this work include two online dust emission schemes (i.e., the Zender and Westphal schemes, nine dust-related heterogeneous reactions, an updated aerosol inorganic thermodynamic module ISORROPIA II with an explicit treatment of crustal species, and the interface between ISORROPIA II and the new dust treatments. The resulting improved CMAQ (referred to as CMAQ-Dust, offline-coupled with the Weather Research and Forecast model (WRF, is applied to the April 2001 dust storm episode over the trans-Pacific domain to examine the impact of new model treatments and understand associated uncertainties. WRF/CMAQ-Dust produces reasonable spatial distribution of dust emissions and captures the dust outbreak events, with the total dust emissions of ~111 and 223 Tg when using the Zender scheme with an erodible fraction of 0.5 and 1.0, respectively. The model system can reproduce well observed meteorological and chemical concentrations, with significant improvements for suspended particulate matter (PM, PM with aerodynamic diameter of 10 μm, and aerosol optical depth than the default CMAQ v4.7. The sensitivity studies show that the inclusion of crustal species reduces the concentration of PM with aerodynamic diameter of 2.5 μm (PM_2.5 over polluted areas. The heterogeneous chemistry occurring on dust particles acts as a sink for some species (e.g., as a lower limit estimate, reducing O₃ by up to 3.8 ppb (~9% and SO₂ by up to 0.3 ppb (~27% and as a source for some others (e.g., increasing fine-mode SO₄²⁻ by up to 1.1 μg m⁻³ (~12% and PM_2.5 by up to 1.4 μg m⁻³ (~3% over the domain. The

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

Energy Technology Data Exchange (ETDEWEB)

Gulson, Brian, E-mail: brian.gulson@mq.edu.au [Graduate School of the Environment, Macquarie University, North Ryde NSW 2109 (Australia); CSIRO Earth Science and Resource Engineering, North Ryde NSW 2113 (Australia); Anderson, Phil [Information and Statistics Group, Australian Institute of Health and Welfare, Canberra ACT 2601 (Australia); Faculty of Health, University of Canberra, Canberra ACT 2601 (Australia); Taylor, Alan [Department of Psychology, Macquarie University, Sydney NSW 2109 (Australia)

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

Analysis of Dust and Fission Products in PBMR Turbine

International Nuclear Information System (INIS)

Stempniewicz, M.M.; Wessels, D.

2014-01-01

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

Electrostatic Dust Detector with Improved Sensitivity

International Nuclear Information System (INIS)

Boyle, D.P.; Skinner, C.H.; Roquemore, A.L.

2008-01-01

Methods to measure the inventory of dust particles and to remove dust if it approaches safety limits will be required in next-step tokamaks such as ITER. An electrostatic dust detector, based on a fine grid of interlocking circuit traces, biased to 30 or 50 V, has been developed for the detection of dust on remote surfaces in air and vacuum environments. Gaining operational experience of dust detection on surfaces in tokamaks is important, however the level of dust generated in contemporary short-pulse tokamaks is comparatively low and high sensitivity is necessary to measure dust on a shot-by-shot basis. We report on modifications in the detection electronics that have increased the sensitivity of the electrostatic dust detector by a factor of up to 120, - a level suitable for measurements on contemporary tokamaks.

Distribution, Seasonal Variations and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Foliar Dust of Nanjing, China.

Science.gov (United States)

Zha, Yan; Zhang, Yinlong; Ma, Zilong; Tang, Jie; Sun, Kai

2018-04-01

Polycyclic aromatic hydrocarbons (PAHs) are of concern for both ecosystem and human health due to their potential teratogenic, carcinogenic, and mutagenic properties. The concentration of ∑ 16 PAHs in foliar dust ranged from 49.4 to 19,018.1 µg kg -1 , with a mean value of 7074.5 µg kg -1 . There were significant seasonal variations in the concentration of ∑ 16 PAHs, with the concentration in winter being almost twice as high as in summer. Similarly, the differences between PAH profiles in different seasons indicated that they had common sources, which were attributed to the combined effect of regional transport and local emissions. The diagnostic ratios of indicator compounds indicated that PAHs detected in foliar dust originated from a mixture of gasoline vehicle emissions, biomass, and coal combustion in Nanjing. According to the ecological risk classification of ∑ 16 PAHs, the ecological risk caused by PAHs was high since the value of RQ ∑16PAHs(MPCs) was ≥ 1 and RQ ∑16PAHs(NCs) were ≥ 800. The mean values for RQ∑ 16 PAHs (MPCs) and RQ∑ 16 PAHs (NCs) were 14.8 and 2368.9, which indicated a relatively high ecological risks of PAHs in foliar dust in Nanjing.

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

OpenAIRE

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

2010-01-01

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

Predictors of Airborne Endotoxin Concentrations in Inner City Homes

Science.gov (United States)

Mazique, D; Diette, GB; Breysse, PN; Matsui, EC; McCormack, MC; Curtin-Brosnan, J; Williams, D; Peng, RD; Hansel, NN

2011-01-01

Few studies have assessed in-home factors which contribute to airborne endotoxin concentrations. In 85 inner-city Baltimore homes, we found no significant correlation between settled dust and airborne endotoxin concentrations. Certain household activities and characteristics, including frequency of dusting, air conditioner use and type of flooring, explained 36–42% of the variability of airborne concentrations. Measurements of both airborne and settled dust endotoxin concentrations may be needed to fully characterize domestic exposure in epidemiologic investigations. PMID:21429483

Growth of lowland broccoli coconut coir dust and peat based growing media using fertigation system

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Asiah; Abdul Rahman, Shyful Azizi; Nordin, Latiffah; Abdullah, Hazlina; Ruslan, Abdul Razak [Malaysian Inst. for Nuclear Technology Research MINT, Bangi (Malaysia). Agrotechnology and Bioscineces Div.; Taib, Mohd Idris [Malaysian Inst. for Nuclear Technology Research MINT, Bangi (Malaysia). Intelligent Group

2004-07-01

A study was carried out inside the greenhouse to determine the response of lowland broccoli (Brassica oleracea) plants grown in five mixtures of coconut coir dust and peat as the growing media. The growing mixes were prepared in the following ratios (% by vol): 100% coconut coir dust, 75% coconut coir dust + 25% peat, 50% coconut coir dust + 50% peat, 25% coconut coir dust + 75% peat and 100% peat. The plants were supplied with 200 mg 1-1 nitrogen using a computerized fertigation system developed at MINT Plants grown on 100% peat exhibited reduced plant growth and yield compared to plants grown on mixes containing coconut coir dust. Plants growth and yield were increased on growing media contained > 50% coconut coir dust; however, the highest total plant dry weight, plant height and yield were obtained from plants grown on 100% coconut coir dust. Total nitrogen concentration in the leaves and stems was not significantly different in all mixture of the growing media regardless of whether coconut coir dust or peat was used. In general, nitrate -nitrogen concentrations were lowest in the floret than in the leaves and stem tissues of plants grown on all growing media used in the study. However, nitrate-nitrogen concentrations in the leaves, stems and florets were lowest in the plants grown on 100% peat compared to the plants grown on growing media containing coconut coir dust. The concentrations of nitrate-nitrogen in the florets, which ranged from 290 to 450 mg N kg-l/dry weight, are considered to be under permissible levels by European standards. (Author)

Growth of lowland broccoli coconut coir dust and peat based growing media using fertigation system

International Nuclear Information System (INIS)

Asiah Ahmad; Shyful Azizi Abdul Rahman; Latiffah Nordin; Hazlina Abdullah; Abdul Razak Ruslan; Mohd Idris Taib

2004-01-01

A study was carried out inside the greenhouse to determine the response of lowland broccoli (Brassica oleracea) plants grown in five mixtures of coconut coir dust and peat as the growing media. The growing mixes were prepared in the following ratios (% by vol): 100% coconut coir dust, 75% coconut coir dust + 25% peat, 50% coconut coir dust + 50% peat, 25% coconut coir dust + 75% peat and 100% peat. The plants were supplied with 200 mg 1-1 nitrogen using a computerized fertigation system developed at MINT Plants grown on 100% peat exhibited reduced plant growth and yield compared to plants grown on mixes containing coconut coir dust. Plants growth and yield were increased on growing media contained > 50% coconut coir dust; however, the highest total plant dry weight, plant height and yield were obtained from plants grown on 100% coconut coir dust. Total nitrogen concentration in the leaves and stems was not significantly different in all mixture of the growing media regardless of whether coconut coir dust or peat was used. In general, nitrate -nitrogen concentrations were lowest in the floret than in the leaves and stem tissues of plants grown on all growing media used in the study. However, nitrate-nitrogen concentrations in the leaves, stems and florets were lowest in the plants grown on 100% peat compared to the plants grown on growing media containing coconut coir dust. The concentrations of nitrate-nitrogen in the florets, which ranged from 290 to 450 mg N kg-l/dry weight, are considered to be under permissible levels by European standards. (Author)

Black carbon and mineral dust in snow cover on the Tibetan Plateau

Science.gov (United States)

Zhang, Yulan; Kang, Shichang; Sprenger, Michael; Cong, Zhiyuan; Gao, Tanguang; Li, Chaoliu; Tao, Shu; Li, Xiaofei; Zhong, Xinyue; Xu, Min; Meng, Wenjun; Neupane, Bigyan; Qin, Xiang; Sillanpää, Mika

2018-02-01

Snow cover plays a key role for sustaining ecology and society in mountainous regions. Light-absorbing particulates (including black carbon, organic carbon, and mineral dust) deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snow and ice. This study focused on understanding the role of black carbon and other water-insoluble light-absorbing particulates in the snow cover of the Tibetan Plateau (TP). The results found that the black carbon, organic carbon, and dust concentrations in snow cover generally ranged from 202 to 17 468 ng g-1, 491 to 13 880 ng g-1, and 22 to 846 µg g-1, respectively, with higher concentrations in the central to northern areas of the TP. Back trajectory analysis suggested that the northern TP was influenced mainly by air masses from Central Asia with some Eurasian influence, and air masses in the central and Himalayan region originated mainly from Central and South Asia. The relative biomass-burning-sourced black carbon contributions decreased from ˜ 50 % in the southern TP to ˜ 30 % in the northern TP. The relative contribution of black carbon and dust to snow albedo reduction reached approximately 37 and 15 %, respectively. The effect of black carbon and dust reduced the snow cover duration by 3.1 ± 0.1 to 4.4 ± 0.2 days. Meanwhile, the black carbon and dust had important implications for snowmelt water loss over the TP. The findings indicate that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections, particularly in the high-altitude cryosphere.

NRC's limit on intake of uranium-ore dust

International Nuclear Information System (INIS)

McGuire, S.A.

1983-04-01

In 1960 the Atomic Energy Commission adopted an interim limit on the intake by inhalation of airborne uranium-ore dust. This report culminates two decades of research aimed at establishing the adequacy of that limit. The report concludes that the AEC underestimated the time that thorium-230, a constituent of uranium-ore dust, would remain in the human lung. The AEC assumed that thorium-230 in ore dust would behave like uranium with a 120-day biological half-life in the lung. This report concludes that the biological half-life is actually on the order of 1 year. Correcting the AEC's underestimate would cause a reduction in the permitted airborne concentration of uranium-ore dust. However, another factor that cancels the need for that reduction was found. The uranium ore dust in uranium mills was found to occur with very large particle sizes (10-micron activity median aerodynamic diameter). The particles are so large that relatively few of them are deposited in the pulmonary region of the lung, where they would be subject to long-term retention. Instead they are trapped in the upper regions of the respiratory tract, subsequently swallowed, and then rapidly excreted from the body through the gastrointestinal tract. The two effects are of about the same magnitude but in opposing directions. Thus the present uranium-ore dust intake limit in NRC regulations should provide a level of protection consistent with that provided for other airborne radioactive materials. The report recalculates the limit on intake of uranium-ore dust using the derived air concentrations (DAC) from the International Commission on Radiological Protection's recent Publication 30. The report concludes that the silica contained in uranium-ore dust is a greater hazard to workers than the radiological hazard

Neutron activation analysis of size-separated airborne dust particles, (2)

International Nuclear Information System (INIS)

Aoki, Atsushi; Ishii, Taka; Tomiyama, Tsuyoshi; Yamamoto, Isao.

1976-01-01

The size distribution of the component element concentration in particle floating matters contained in the atmosphere is related closely to atmospheric pollution. In this paper, the results of the neutron activation analysis and the measurement of size distribution of component element concentration are reported, which were carried out in Minami-ku, Kyoto, in May and November, 1975, by collecting airbone dust with Andersen air samples. The activation of samples was carried out with the research reactor in Kyoto University. The gamma-ray spectra of the samples were measured with a Ge(Li) semiconductor detector. The size distributions of Al, Sc, Th and Ti showed the similar pattern. The concentration of Zn was abnormally high as compared with that in other districts, and it is related to the local industry in this district. The size distribution of airborne dust usually follows the logarithmic normal distribution when it is not affected by atmospheric pollution. Accordingly, the size distribution of the concentration also follows the same distribution. The accumulated percentages of the concentrations of Al, Sc and Th fall on the same straight line, and it means that these elements were contained in the same particles as the components. Also it was decided that the particles of Al, Sc, Th, Fe and Ti were soil particles. (Kako, I.)

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

Science.gov (United States)

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

2015-11-01

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

Star formation at high redshift and the importance of dust obscuration

DEFF Research Database (Denmark)

Michalowski, Michal

One of the aspects of the understanding of the Universe evolution is its star formation history. In order to gain a complete picture of the Universe evolution it is important to know when the stars we see today were formed. One of the method to study this problem is to use far-infrared and radio...... emission of galaxies. In this way it is possible to investigate the sites of star formation that are totally obscured by dust and therefore invisible at the optical wavelengths. It is because the energy absorbed by dust in the optical is re-emitted in the infrared, whereas radio emission is unaffected...... and/or radio, namely their enhanced submillimeter / radio emission combined with optical faintness and blue colors. I find that these four galaxies are young, highly star-forming, low-mass and dusty....

Measurements of radioactive dust in high altitude air

International Nuclear Information System (INIS)

Kobayashi, Mika; Kohara, Eri; Muronoi, Naohiro; Masuda, Yousuke; Midou, Tomotaka; Ishida, Yukiko; Shimizu, Toshihiko; Saga, Minoru; Endo, Hiromu

2012-01-01

The radioactivity in samples of airborne dust was measured. The samples had been collected at high altitude by the Japan Air Self-Defense Force. The data were obtained for the gross beta activity, gamma nuclide determination and radiochemical analysis. It was shown that there was no appreciable difference between the activity levels obtained in this time and in the year before. Seasonal variations were not very pronounced. It was found that the radioactivity at high altitude had been stable at a low level. Radioactive gases (gaseous radioiodine and xenon gas) were not detected. This report does not include the result on radionuclide measurements that Technical Research and Development Institute executed for examining the nuclear emergency situation at Fukushima Daiichi and Daini nuclear power plants after Tohoku Region Pacific Ocean Earthquake on March 11, 2011. (author)

Elementary analysis of airborne dust (preliminary findings of the AFR Coordinated Airborne Dust Programme (LVPr))

International Nuclear Information System (INIS)

1983-03-01

In March 1981 the systematic measuring of 15 elements of airborne dust was started in the Coordinated Airborne Dust Program (LVPr) by the Association for the Promotion of Radionuclide Technology (AFR). The sampling was done under comparable conditions at five selected places within the Federal Republic of Germany by using especially developed large-filter High Volume Samplers. The aim of this research is to establish the foundation for further investigations on the effects of the current given element concentrations on human life. When the results of the first half-year (summer period) were in hand, these element concentrations, which had been analysed using different methods, were presented to a group of experts, also with the experience gained with the analytical methods, in order to critically assess procedure and philosophy of this study. This evaluation was done on the occasion of a colloquium on Jun 29th, 1982 at the Karlsruhe Nuclear Research Centre. The presented AFR-Report contains the papers and the discussions of this meeting as well as the average element data with respect to the sampling time between 15th and 40th week of the year 1981. The discussion contributions presented here correspond to the essential statements that have been given and recorded. A total classification of all data relating to the whole sampling time of the LVPr will be given in AFR-Report No. 007. (orig.) [de

House dust in seven Danish offices

Science.gov (United States)

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

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

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

Science.gov (United States)

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

2012-06-01

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

Occurrence of trace elements in respirable coal dust

International Nuclear Information System (INIS)

Sahoo, B.N.

1991-01-01

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

Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

International Nuclear Information System (INIS)

Walsh, P T; Forth, A R; Clark, R D R; Dowker, K P; Thorpe, A

2009-01-01

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction

Energy Technology Data Exchange (ETDEWEB)

Krupadam, Reddithota J.; Bhagat, Bhagyashree; Khan, Muntazir S. [National Environmental Engineering Research Institute, Nagpur (India)

2010-08-15

A method based on solid-phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L{sup -1} (r=0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials - powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD) - and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L{sup -1} for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained. (orig.)

Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction.

Science.gov (United States)

Krupadam, Reddithota J; Bhagat, Bhagyashree; Khan, Muntazir S

2010-08-01

A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained.

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

Science.gov (United States)

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

2015-12-01

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

Characteristics and transport of organochlorine pesticides in urban environment: air, dust, rain, canopy throughfall, and runoff.

Science.gov (United States)

Zhang, Wei; Ye, Youbin; Hu, Dan; Ou, Langbo; Wang, Xuejun

2010-11-01

Characteristics and transport of organochlorine pesticides (OCPs) in urban multiple environments, including air, dust, rain, canopy throughfall, and runoff water, are explored in this study. Hexachlorocyclohexanes (HCHs) dominated in both air and rain water, and dichlorodiphenyltrichloroethane (DDT) related substances showed a higher affinity to dust. Relatively high concentrations of DDT and dichlorodiphenyldichloroethylene (DDE) in air, rain and dust imply that technical DDT in the environment has been degrading, and there may be unknown local or regional emission sources that contain DDTs in the study area. Source identification showed that DDTs in Beijing urban environments with a fresh signature may originate from the atmospheric transport from remote areas. The ratio of α-/γ-HCH in dust, rain, canopy throughfall and runoff were close to 1, indicating the possible use of lindane. OCPs in runoff were transported from various sources including rain, dust, and canopy throughfall. In runoff, DDTs and hexachlorobenzene (HCB) were mainly transported from dust, and HCHs were mainly from rain and canopy throughfall.

Atmospheric dust events in central Asia: Relationship to wind, soil type, and land use

Science.gov (United States)

Pi, Huawei; Sharratt, Brenton; Lei, Jiaqiang

2017-06-01

Xinjiang Province in northwest China is one of the most important source regions of atmospheric dust in the world. Spatial-temporal characteristics of dust events in the province were investigated by time series analysis of annual dust event frequency and meteorological data collected at 101 meteorological stations from 1960 to 2007. Blowing dust frequency (BDF) and dust storm frequency (DSF) decreased with time in North, South, and East Xinjiang whereas floating dust frequency (FDF) decreased with time only in South and East Xinjiang. Dust concentrations were lower in North than in South Xinjiang and decreased with time in East Xinjiang. Wind significantly influenced the temporal trend in FDF, BDF, and DSF in South Xinjiang and DSF in North Xinjiang. Frequency of dust events was smaller by an order of magnitude in North (10.9 d yr-1) than in South Xinjiang (111.3 d yr-1), possibly due in part to higher annual precipitation in North Xinjiang. Floating dust was most frequently observed in East and South Xinjiang, while blowing dust was most frequently observed in North Xinjiang. The high frequency of floating dust in East and South Xinjiang is likely due to the enclosed terrain that characterizes these regions. Land use and soil type also influenced dust events. Although climate influences frequency of dust events, the occurrence of these events may be reduced most effectively by imposing better land management practices in deciduous forests or orchards characterized by saline soils in respectively North and East Xinjiang and meadows characterized by Guanyu soils in South Xinjiang.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

THREATS/RISKS IN POULTRY FARMS: MICROBIOLOGICAL CONTAMINANTS, DUST, ODOURS AND BIOLOGICAL METHOD FOR ELIMINATION

Directory of Open Access Journals (Sweden)

Katarzyna Matusiak

2017-06-01

Full Text Available The aim of the study was to evaluate the microbiological contamination, odour and dust concentration in poultry farms. In addition, the effectiveness of biopreparation and Yucca schidigera plant extract in manure hygienisation and selected odorous compounds removal was determined. The airborne total dust concentration at poultry production premises averaged 1.44 mg/m3 with a high percentage of the PM10 fraction. High number of bacteria and fungi at 106-1010 CFU / g. was determined in both poultry manure and settled dust. Poultry farm’s air limits of the bacteria and fungi number have not been exceeded. Reported concentrations of PM2.5 and PM10 fractions were 18-20 times higher than acceptable for a 24-hour exposure determined by the World Health Organization. Volatile odorous compounds dominant in poultry farms were: ammonia, acrolein, methyl amine, acetic acid, acetaldehyde and formaldehyde. The concentrations are variable depending on the farm type and stage of the cycle production. The permissible concentration/ exposure limits of ammonia in the air has been exceeded in the laying hens farms I and II, while the concentration of carbon dioxide exceeded the limit value in the third stage of the cycle production on broiler farm III and was close to the limit for laying hens farm I. The maximum cytotoxicity of odorous compounds mixture tested on chick liver hepatocellular carcinoma cell line LMH was 45.7%. It was confirmed by cells morphologic changes after the odorous compounds treatment (ammonia, di-, and trimethylamine. Mineral-microbial biopreparation with Yucca schidigera extract reduced the total number of microorganisms by 1 logarythmic unit in poultry manure and decreased concentration of odorous compounds by 37% - 70% depending on the compound. The use in sequence Y. schidigera extract, and then after 2 days biopreparation can be an effective way to reduce microbiological and odorous hazards on poultry farms.

Open-air sprays for capturing and controlling airborne float coal dust on longwall faces

Science.gov (United States)

Beck, T.W.; Seaman, C.E.; Shahan, M.R.; Mischler, S.E.

2018-01-01

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. PMID:29348700