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Dust
Kinds of Dust Terms modified by Dust Selected AbstractsBridging the gap between field data and global models: current strategies in aeolian researchEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2010Joanna Bullard Abstract Modern global models of earth-atmosphere-ocean processes are becoming increasingly sophisticated but still require validation against empirical data and observations. This commentary reports on international initiatives amongst aeolian researchers that seek to combine field-based data sets and geomorphological frameworks for improving the quality of data available to constrain and validate global models. These include a second iteration of the Dust Indicators and Records from Terrestrial Marine Palaeoenvironments (DIRTMAP2) database, the Digital Atlas of Sand Seas and Dunefields of the World and a new geomorphology-based land surface map produced by the QUEST (Quantifying Uncertainties in the Earth System) Working Group on Dust. Copyright © 2010 John Wiley & Sons, Ltd. [source] Predictors of High Endotoxin Concentrations in the Settled Dust of German HomesINDOOR AIR, Issue 1 2002W. BISCHOF [source] Properties of Portland Cement Pastes Incorporating Nanometer-Sized Franklinite Particles Obtained from Electric-Arc-Furnace DustJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2001Antonio Balderas The present work presents preliminary results concerning ordinary portland cement (OPC) blended with electric-arc-furnace dust (EAFD) obtained from steel-smelting plants. The powder obtained after acid treatment of the EAFD consisted basically of nanometer-sized particles of ZnFe2O4. Incorporation of the EAFD in the OPC produced retardation of the setting process. Nevertheless, after 7 d, the compressive strength of the OPC/EAFD pastes was superior to undoped OPC, and, after 28 d, the extent of hydration of the OPC/EAFD pastes was equivalent to undoped OPC. A compressive strength of 72 MPa was attained after 42 d for OPC doped with 10 wt% EAFD. [source] Method for checking label accuracy in barn and free range eggsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2005Neville G Gregory Abstract The aim was to develop a method for testing whether eggs sold as either ,barn' or free range' were laid under cage conditions. The surface patterns on 11 520 eggs from cage, barn and free range production systems were examined under ultraviolet light for distinctive fluorescent marks associated with each production system. In addition, the effects of egg washing, egg size, condensation and cage dusting on the prevalence of the fluorescent patterns associated with the cage production system were examined. The prevalence of fluorescent white double parallel lines with 2.2,2.5 cm spacing was a distinguishing feature for eggs laid on wire floors in cages. If five or more eggs in a sample of 90 eggs have double fluorescent lines it can be concluded with greater than 999 in 1000 probability that the batch contains some cage-laid eggs. Dust from the egg collection area below the feed trough was the main source of the fluorescent material. Washing the eggs removed or obscured the double lines. Egg size and condensation had limited effects on the prevalence of double lines. Infrequent dusting of the wire floor did not reduce the value of the test. Copyright © 2005 Society of Chemical Industry [source] Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foilsMETEORITICS & PLANETARY SCIENCE, Issue 1-2 2008A. T. Kearsley By comparison to laboratory shots of known particle dimensions and density, using the same velocity and incidence geometry as the Stardust Wild 2 encounter, we can derive size and mass of the cometary dust grains. Using scanning electron microscopy (SEM) of foil samples (both flown on the mission and impacted in the laboratory) we have recognized a range of impact feature shapes from which we interpret particle density and internal structure. We have documented composition of crater residues, including stoichiometric material in 3 of 7 larger craters, by energy dispersive X-ray microanalysis. Wild 2 dust grains include coarse (>10 ,m) mafic silicate grains, some dominated by a single mineral species of density around 3,4 g cm,3 (such as olivine). Other grains were porous, low-density aggregates from a few nanometers to 100 ,m, with an overall density that may be lower than 1 g cm,3, containing mixtures of silicates and sulfides and possibly both alkali-rich and mafic glass. The mineral assemblage is very similar to the most common species reported from aerogel tracks. In one large aggregate crater, the combined diverse residue composition is similar to CI chondrites. The foils are a unique collecting substrate, revealing that the most abundant Wild 2 dust grains were of sub-micrometer size and of complex internal structure. Impact residues in Stardust foil craters will be a valuable resource for future analyses of cometary dust. [source] Opportunities for the stratospheric collection of dust from short-period cometsMETEORITICS & PLANETARY SCIENCE, Issue 11 2002Scott MESSENGER These comets have had the rare characteristics of low eccentricity, low inclination orbits with nodes very close to 1 AU. Dust from these comets is directly injected into Earth-crossing orbits by radiation pressure, unlike the great majority of interplanetary dust particles collected in the stratosphere which spend millennia in space prior to Earth-encounter. Complete dust streams from these comets form within a few decades, and appreciable amounts of dust are accreted by the Earth each year regardless of the positions of the parent comets. Dust from these comets could be collected in the stratosphere and identified by its short space exposure age, as indicated by low abundances of implanted solar-wind noble gases and/or lack of solar flare tracks. Dust from Grigg-Skjellerup probably has the highest concentration at Earth orbit. We estimate that the proportion of dust from this comet will reach at least several percent of the background interplanetary dust flux in the >40 ,m size range during April 23,24 of 2003. [source] Lives of Dust and Water: An Anthropology of Change and Resistance in Northwestern Mexico by María Luz Cruz-TorresAMERICAN ETHNOLOGIST, Issue 3 2010CARMEN MARTÍNEZ NOVO No abstract is available for this article. [source] Occupational therapy adaptation of the home environment in Sweden for people with asthmaOCCUPATIONAL THERAPY INTERNATIONAL, Issue 4 2002Doctoral Candidate, Margot Frisk Occupational Therapist Abstract The purpose of this study was to evaluate changes of lung function, respiratory symptoms and indoor air quality after reducing allergens and indoor pollutants in the home environment of people with asthma (n = 21). A quasi-experimental pre-/post-test design with one group of participants was implemented. The interventions included removal of wall-to-wall carpets (n = 14) or improvement of indoor air exchange (n = 7). Participants' lung function, symptoms, medication and type-1 allergy were recorded before and after the intervention. The indoor environment was monitored at house calls by an occupational therapist using conventional physical, biological and chemical methods. There was an improvement of lung function evidenced by an increased mean Forced Expiratory Volume (FEV1 %) and a reduction of airway obstruction (reversibility, % of baseline value), which indicate an improved asthmatic condition. Lung function assessed by vital capacity, bronchial hyper-responsiveness, mean of Peak Expiratory Flow, symptom score and medicine consumption did not change significantly. There was a tendency that the amount of airborne dust (p=0.06) was reduced in the indoor environment. Relative humidity, carbon dioxide, formaldehyde and house dust mite levels had decreased after the intervention, but not significantly. Asthma symptoms related to the home environment are probably caused by several factors. When people with asthma suffer from increased symptoms in the home, house calls should be performed routinely. Dust samples from beds and carpets for analysis of allergens give information about exposure, and environmental assessments should be performed before interventions. Occupational therapists can make a valuable contribution in evaluating the home environment and suggesting ergonomic adaptations for individuals with asthma. Copyright © 2002 Whurr Publishers Ltd. [source] Mortality among Ontario members of the International Union of Bricklayers and Allied CraftworkersAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2005Murray M. Finkelstein PhD Abstract Background Dust exposed workers may be at increased risk of pneumoconiosis, stomach cancer, lung cancer, and obstructive lung disease. Bricklayers may experience high exposures to silica and inorganic dusts. The aim of this study was to examine the mortality pattern of bricklayers to identify occupational associations with mortality. Methods A cohort of 10,953 workers was assembled from records of the International Union of Bricklayers and Allied Craftworkers (IUBAC). Mortality was ascertained by linkage to the Canadian Mortality Registry at Statistics Canada. Standardized Mortality Ratios (SMRs) were computed using Ontario general population mortality rates as the reference. Results Twenty or more years from first membership, SMRs for lung (158; 130,190) and stomach (235; 140,370) cancers were significantly elevated. There were four deaths from pneumoconiosis, but non-malignant respiratory mortality SMRs were not increased. Conclusions Bricklayers and Allied Craftworkers are at risk from diseases associated with heavy exposure to inorganic dust: lung cancer, stomach cancer, and pneumoconiosis. Dust control as well as education and training of these workers to protect themselves against inhalation hazards is necessary. Am. J. Ind. Med. 47:4,9, 2005. © 2004 Wiley-Liss, Inc. [source] Characterization of Acanthamoeba Isolates from Dust of a Public Hospital in Curitiba, Paraná, BrazilTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 1 2010ADRIANA O. COSTA ABSTRACT. Occurrence of Acanthamoeba in the hospital environment may represent a health risk for patients, since these organisms can cause severe opportunistic illness, such as keratitis, and also can harbor pathogenic agents. We analyzed the dust from some environments of a public hospital in Curitiba, Parana State, Brazil. Two distinct populations of Acanthamoeba were isolated in five locations and morphologically classified as group I and group II according to Pussard and Pons. Isolates were identified as Acanthamoeba by PCR using primers to amplify a region of 18S rDNA, which showed variation in the product length among the isolates. A cloned culture of group II showed greater growth at 37 °C and in media with 0.1, 0.5, and 1.0 M mannitol, which are the physiological characteristics of pathogenic Acanthamoeba. Monitoring the presence of Acanthamoeba in hospital units, as well as evaluating the pathogenicity of the isolates, can be an approach to alert the health professionals to improve the disinfection procedures and minimize the risks of treating this problematic disease caused by this protozoan. [source] Mexico's Ejidos and the Larger WorldANTHROPOLOGY OF WORK REVIEW, Issue 3 2006Leslie Johnson Lives of Dust and Water: An Anthropology of Change and Resistance in Northwestern Mexico. María Luz Cruz-Torres. Tucson: University of Arizona Press, 2004. Fields of Power, Forests of Discontent: Culture, Conservation, and the State in Mexico. Nora Haenn. Tucson: University of Arizona Press, 2005. [source] ChemInform Abstract: Synthesis of Indolones and Quinolones by Reductive Cyclization of o-Nitroaryl Acids Using Zinc Dust and Ammonium Formate.CHEMINFORM, Issue 46 2008Bhima Reddy Dinesh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Respiratory effects of exposure to low levels of concrete dust containing crystalline silicaAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2001E. Meijer MD Abstract Background Dusts containing crystalline silica are generated in mining, construction, glass, granite and concrete production industries. The association between exposure to low levels of concrete dust containing crystalline silica and reduction in lung function, was evaluated in a cross-sectional study. Methods The study was carried out among 144 concrete workers, from two factories, with exposure assessment of respirable dust and silica by personal samplers. Results of respiratory questionnaires and standardized measurements of lung function were compared with the results in a control population. Multiple linear regression analysis was used in selecting factors that predict (age and standing height standardized residual) lung function. Results The average concentration of respirable dust in both factories was 0.8 mg/m3 and 0.06 mg/m3 for respirable silica. The average silica content of the dust was 9%. The average cumulative dust exposure was 7.0 mg/m3 year and cumulative silica exposure was 0.6 mg/m3 year. Significant associations between exposure to concrete dust and a small lung function (FEV1/FVC ratio, MMEF) loss were found, independent of smoking habits and of a history of allergy. Conclusions Our results indicate that, concrete workers with chronic obstructive pulmonary symptoms and/or work-related lower respiratory symptoms are at risk of having a reduction in lung function (FEV&1/FVC ratio) outside the 5th percentile of the external reference population, and therefore, of mild chronic obstructive pulmonary disease, at respirable concrete dust levels below 1 mg/m3 with a respirable crystalline silica content of 10% (TWA, 8 hr). Am. J. Ind. Med. 40:133,140, 2001. © 2001 Wiley-Liss, Inc. [source] Effect of Mineral Dusts on the Growth of Silicate Bacteria S35ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2008DAI Qunwei Abstract In order to compare the chemical compositions and physical properities of dusts on silicate bacteria S35, the chemical compositions of six kinds of mineral dusts have been analyzed and the changes of pH value, glucose (GLU), electrolyte and Mn, Si, Fe before and after the dusts reacted with silicate bacteria S35 have been measured. The SEM analysis has been used to study the bacterial form and interface action status in the course of reaction between dusts and bacteria. The results show that these mineral dusts have different effects on experiment bacteria. Therefore, it is concluded that the effect of mineral dusts on silicate bacteria has correlation with the chemical compositions and physical properities of dusts. [source] An In Vitro Investigation of Pulmonary Alveolar Macrophage Cytotoxicity Introduced by Fibrous and Grainy Mineral DustsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2006DONG Faqin Abstract, In order to study the damage mechanism of mineral dusts on the pulmonary alveolar macrophage (AM), the changes in their death ratio, malandialdthyde (MDA) content and activities of lactate dehydrogenase (LDH) and superoxide dismutase (SOD) were measured, and the technique of cell culture in vitro was used to investigate the cytotoxicity of six mineral dusts (twelve crystal habits) from twelve mineral deposits. The results show that wollastonite and clinoptilolite have no AM cytotoxicity, while other fibrous and grainy mineral dusts damage pulmonary AM in various degrees. The cytotoxicity of fibrous mineral dusts was greater than that of the grainy ones, and the cytotoxicity of dusts was positively correlated with the active OH content in dusts, but not necessarily so with its SiO2 content. The high pH values produced by dust was unfavorable for the survival of cells and the dusts with low bio-resistance were safe for cells. The content of variable valence elements in dusts might influence their cytotoxicity and the surface charge of dusts was not a stable factor for their toxicity. It is demonstrated that the shape of mineral dusts was one of the factors affecting cytotoxicity, and that the cytotoxicity of mineral dusts depends mainly on their properties. [source] Associations of risk factors obesity and occupational airborne exposures with CDKN2A/p16 aberrant DNA methylation in esophageal cancer patientsDISEASES OF THE ESOPHAGUS, Issue 7 2010S. Mohammad Ganji SUMMARY It is known that obesity and occupational airborne exposure such as dust are among risk factors of esophageal cancer development, in particular squamous cell carcinoma (SCC) of esophagus. Here, we tested whether these factors could also affect aberrant DNA methylation. DNAs from 44 fresh tumor tissues and 19 non-tumor adjacent normal tissues, obtained from 44 patients affected by SCC of esophagus (SCCE), were studied for methylation at the CDKN2A/p16 gene promoter by methylation-specific polymerase chain reaction assay. Statistical methods were used to assess association of promoter methylation with biopathological, clinical, and personal information data, including obesity and airborne exposures. Methylation at the CDKN2A/p16 gene promoter was detected in 12 out of 44 tumor samples. None of the non-tumor tissues exhibited the aberrant methylation. Our results confirmed previously described significant association with low tumor stage (P= 0.002); in addition, we found that obesity (P= 0.001) and occupational exposure (P= 0.008) were both significantly associated with CDKN2A/p16 promoter methylation. This study provides evidence that obesity and occupational exposure increase the risk of developing esophageal cancer through an enhancement of CDKN2A/p16 promoter methylation. [source] Evaluation of a wind erosion model in a desert area of northern Asia by eddy covarianceEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2009Gerardo Fratini Abstract For the first time, vertical fluxes of mineral dust measured by Eddy Covariance in two desert sites of Northern Asia have been used to test the performances of a wind erosion model in the field. Soil parameters required by the model were obtained through field and laboratory determinations. Model predictions and direct measurements have been compared. The main finding was that the direction of the horizontal wind relative to the orientation of nebkhas played a crucial role in determining the emission of particles in one of the investigated sites. Being unable to simulate such interaction, the model generally overestimated the actual emission. It provided, instead, reliable predictions (r2 = 0·87) when the wind direction was suitable in detaching loose erodible elements placed on nebkhas thanks to their normal orientation. Copyright © 2009 John Wiley & Sons, Ltd. [source] Windblown dust influenced by conventional and undercutter tillage within the Columbia Plateau, USA,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2009B. S. Sharratt Abstract Exceedance of the US Environmental Protection Agency national ambient air quality standard for PM10 (particulate matter ,10 µm in aerodynamic diameter) within the Columbia Plateau region of the Pacific Northwest US is largely caused by wind erosion of agricultural lands managed in a winter wheat,summer fallow rotation. Land management practices, therefore, are sought that will reduce erosion and PM10 emissions during the summer fallow phase of the rotation. Horizontal soil flux and PM10 concentrations above adjacent field plots (>2 ha), with plots subject to conventional or undercutter tillage during summer fallow, were measured using creep and saltation/suspension collectors and PM10 samplers installed at various heights above the soil surface. After wheat harvest in 2004 and 2005, the plots were either disked (conventional) or undercut with wide sweeps (undercutter) the following spring and then periodically rodweeded prior to sowing wheat in late summer. Soil erosion from the fallow plots was measured during six sampling periods over two years; erosion or PM10 loss was not observed during two periods due to the presence of a crust on the soil surface. For the remaining sampling periods, total surface soil loss from conventional and undercutter tillage ranged from 3 to 40 g m,2 and 1 to 27 g m,2 while PM10 loss from conventional and undercutter tillage ranged from 0·2 to 5·0 g m,2 and 0·1 to 3·3 g m,2, respectively. Undercutter tillage resulted in a 15% to 65% reduction in soil loss and 30% to 70% reduction in PM10 loss as compared with conventional tillage at our field sites. Therefore, based on our results at two sites over two years, undercutter tillage appears to be an effective management practice to reduce dust emissions from agricultural land subject to a winter wheat,summer fallow rotation within the Columbia Plateau. Copyright © 2009 John Wiley & Sons, Ltd. [source] Techniques to measure the dry aeolian deposition of dust in arid and semi-arid landscapes: a comparative study in West NigerEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2008Dirk Goossens Abstract Seven techniques designed to measure the dry aeolian deposition of dust on a desert surface were tested during field experiments in Niger, central-west Africa. Deposition fluxes were measured during eight periods of 3,4 days each. Experimental techniques tested were the MDCO (marble dust collector) method, the Frisbee method, the glass plate method (optical analysis of dust deposited on glass surfaces using particle imaging software), the soil surface method (deposition on a simulated desert floor) and the CAPYR (capteur pyramidal) method. Theoretical techniques tested were the inferential method and the combination method (gradient method extended with a deposition term for coarse dust particles). The results obtained by the MDCO, Frisbee, inferential and combination methods could be directly compared by converting the data to identical standard conditions (deposition on a water surface producing no resuspension). The results obtained by the other methods (glass plate, soil surface, CAPYR) were compared relatively. The study shows that the crude (unconverted) deposition fluxes of the five experimental techniques were similar, while the crude deposition fluxes calculated by the two theoretical techniques were substantially higher, of the order of four to five times as high as for the experimental techniques. Recalculation of the data to identical environmental conditions (the standard water surface) resulted in nearly identical deposition fluxes for the MDCO, Frisbee, inferential and combination techniques, although the latter two still had slightly higher values (but the differences remained small). The measurements illustrate the need to include a grain shape factor in theoretical dust deposition models. Without such a factor, theoretical models overestimate the deposition. The paper also discusses the advantages and disadvantages of the techniques tested. Copyright © 2007 John Wiley & Sons, Ltd. [source] Geochemical mapping of carbonate sediments in the Makgadikgadi basin, Botswana using moderate resolution remote sensing dataEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2006Kevin White Abstract This paper maps the carbonate geochemistry of the Makgadikgadi Pans region of northern Botswana from moderate resolution (500 m pixels) remotely sensed data, to assess the impact of various geomorphological processes on surficial carbonate distribution. Previous palaeo-environmental studies have demonstrated that the pans have experienced several highstands during the Quaternary, forming calcretes around shoreline embayments. The pans are also a significant regional source of dust, and some workers have suggested that surficial carbonate distributions may be controlled, in part, by wind regime. Field studies of carbonate deposits in the region have also highlighted the importance of fluvial and groundwater processes in calcrete formation. However, due to the large area involved and problems of accessibility, the carbonate distribution across the entire Makgadikgadi basin remains poorly understood. The MODIS instrument permits mapping of carbonate distribution over large areas; comparison with estimates from Landsat Thematic Mapper data show reasonable agreement, and there is good agreement with estimates from laboratory analysis of field samples. The results suggest that palaeo-lake highstands, reconstructed here using the SRTM 3 arc-second digital elevation model, have left behind surficial carbonate deposits, which can be mapped by the MODIS instrument. Copyright © 2006 John Wiley & Sons, Ltd. [source] Airborne dust deposition in the Okavango Delta, Botswana, and its impact on landformsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2004M. Krah Abstract This study investigated the local-scale generation and movement of dust in the seasonal swamps of the Okavango Delta, Botswana, with a view to examining possible transfer of material between ,ood plains and islands. It was found that most of the dust load was carried in the lowest 3 m of the air column, and consisted mainly of amorphous silica, indicating that dust was generated largely on the ,ood plains. Dust loads were found to be highest above the ,ood plains and lowest over the interiors of islands, probably due to the baf,ing effect of the island trees on wind velocity. The contrast in dust loads between islands and ,ood plains suggests that there is a net transfer of dust from ,ood plains to islands, but it was not possible to quantify this transfer. It is evident, however, that ,ood plains experience net erosion and islands net aggradation. A strong seasonality in dust loads was observed, with the maximum dust loads coinciding with maximum wind velocity in October. This also coincides with peak seasonal ,ooding in the delta, and only non-inundated ,ood plains are capable of generating dust. Years of low ,ood therefore appear to be more dusty. There may also be transfer of material from higher-lying to lower-lying ,ood plains, which may reduce the topographic contrast on the ,ood plains. Copyright © 2004 John Wiley & Sons, Ltd. [source] The role of playas in pedogenic gypsum crust formation in the Central Namib Desert: a theoretical modelEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2001F. D. Eckardt Abstract The formation of Namibia's extensive pedogenic gypsum crusts (CaSO4·2H2O) is interpreted in a new light. It is suggested that gypsum primarily precipitates at isolated points of evaporitic concentration, such as inland playas, and that deflation of evaporitic-rich gypsum dust from these playas contributes to the formation of pedogenic gypsum duricrusts on the coastal gravel plains of the Namib Desert surrounding these playas. This study establishes the nature, extent and distribution of playas in the Central Namib Desert and provides evidence for playa gypsum deflation and gravel plain deposition. Remote sensing shows the distribution of playas, captures ongoing deflation and provides evidence of gypsum deflation. It is proposed that, following primary marine aerosol deposition, both inland playas and coastal sabkhas generate gypsum which through the process of playa deflation and gravel plain redeposition contributes to the extensive pedogenic crusts found in the Namib Desert region. Copyright © 2001 John Wiley & Sons, Ltd. [source] Aeolian dust dynamics in agricultural land areas in Lower Saxony, GermanyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2001Dirk Goossens Abstract The dynamics of fine aeolian dust emitted from agricultural land was investigated over 15 months near Grönheim, Lower Saxony, Germany. The following aspects were studied: airborne dust concentration, the ratio of mineral versus organic dust, the vertical distribution of the particles in the atmosphere, horizontal and vertically integrated horizontal dust flux, vertical dust flux, dust deposition at ground level, grain-size distribution of the mineral dust component, and vertical distribution of organic matter in the dust. Standard meteorological parameters (wind speed and direction, precipitation) were measured as well. Dust activity in Grönheim is high in spring (March,May) and autumn (October,November) and low to very low during the rest of the year. There is a strong relationship between the periods of tillage and the intensity of dust activity. Also, there is high dust activity during wind erosion events. For the year 1999, dust emission due to tillage was 6·6 times higher than dust emission due to wind erosion. A dust transport of 15·8 ton km,1 a,1 was calculated for the first 10 m of the atmosphere in 1999. Total dust transport (in the entire mixing layer) was estimated between 16 and 20 ton km,1 a,1. About 25,30 per cent of this dust is mineral dust, emitted from the fields during tillage or during wind erosion events. In spring and autumn there is a strong vertical stratification in the airborne sediment, with much (coarse) dust in the lower air layers and significantly less (and finer) dust at higher altitudes. In summer and winter, when there is no local dust production, there is no stratification: equal amounts of dust are transported at all heights. The stratification in spring and autumn is exclusively caused by the mineral part of the dust. The organic particles are much better mixed in the atmosphere because of their lower density. Copyright © 2001 John Wiley & Sons, Ltd. [source] "Ultraviolet spring" and the ecological consequences of catastrophic impactsECOLOGY LETTERS, Issue 2 2000Charles S. Cockell Asteroid and comet impacts cause ozone depletion. For the first time, we have quantified the photobiological characteristics of these events and speculate on some of the associated ecological consequences. Following the clearing of stratospheric dust after "impact winter", levels of damaging UVB radiation (280,315 nm) could increase by at least 100%, resulting in an "ultraviolet spring". Many of the taxa stressed by the cold and dark conditions of impact are the same that would be stressed by large increases in UVB radiation. Furthermore, depletion of dissolved organic carbon (DOC) by impact-induced acid rain would increase UVB penetrability into freshwater systems. Although an increase in UVB radiation is an attractive hypothesis for exacerbating the demise of land animals at the Cretaceous-Tertiary (K/T) boundary, e.g. dinosaurs, our calculations suggest the impact into rare sulphate-rich target rock may have prevented an ultraviolet spring in this case. If the K/T impact event had occurred in any other region on Earth, the stress to the biosphere would probably have been considerably greater. [source] Effect of artificial mixtures of environmental polycyclic aromatic hydrocarbons present in coal tar, urban dust, and diesel exhaust particulates on MCF-7 cells in cultureENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2004Brinda Mahadevan Abstract Human exposure to polycyclic aromatic hydrocarbons (PAHs) occurs through complex mixtures. The National Institute of Standards and Technology has established standard reference materials (SRMs) for selected PAH mixtures that are composed of carcinogenic, noncarcinogenic, and weakly carcinogenic compounds, such as those derived from coal tar (SRM 1597), atmospheric particulate matter (SRM 1649), and diesel particulate matter (SRM 1650). To study the effects of PAHs with different carcinogenic potential in complex mixtures, and to investigate the metabolic activation of noncarcinogenic and weakly carcinogenic PAHs to DNA-binding derivatives, artificial mixtures (1597H, 1649H, and 1650H) were prepared in the laboratory. These artificial mixtures contained the same relative ratios of noncarcinogenic and weakly carcinogenic PAHs present in SRM 1597, SRM 1649, and SRM 1650. The human mammary carcinoma-derived cell line MCF-7 was treated with these artificial mixtures and analyzed for PAH-DNA adduct formation and the induction of cytochrome P450 (CYP) enzymes. We found that the artificial mixtures formed lower but detectable levels of DNA adducts 24 and 48 hr after treatment than benzo[a]pyrene. Induction of CYP enzyme activity was measured by the ethoxyresorufin- O -deethylase assay, and the expression of CYP1A1 and CYP1B1 was confirmed by immunoblots. Both noncarcinogenic and weakly carcinogenic PAHs present in the artificial mixtures have the ability to induce CYP1A1 and CYP1B1 in MCF-7 cells and contribute to DNA binding. Therefore, it is necessary to take into account the noncarcinogenic and weakly carcinogenic PAHs present in environmental mixtures in assessing the potential risk associated with human exposure. Environ. Mol. Mutagen. 44:99,107, 2004. © 2004 Wiley-Liss, Inc. [source] Life in Darwin's dust: intercontinental transport and survival of microbes in the nineteenth centuryENVIRONMENTAL MICROBIOLOGY, Issue 12 2007Anna A. Gorbushina Summary Charles Darwin, like others before him, collected aeolian dust over the Atlantic Ocean and sent it to Christian Gottfried Ehrenberg in Berlin. Ehrenberg's collection is now housed in the Museum of Natural History and contains specimens that were gathered at the onset of the Industrial Revolution. Geochemical analyses of this resource indicated that dust collected over the Atlantic in 1838 originated from the Western Sahara, while molecular-microbiological methods demonstrated the presence of many viable microbes. Older samples sent to Ehrenberg from Barbados almost two centuries ago also contained numbers of cultivable bacteria and fungi. Many diverse ascomycetes, and eubacteria were found. Scanning electron microscopy and cultivation suggested that Bacillus megaterium, a common soil bacterium, was attached to historic sand grains, and it was inoculated onto dry sand along with a non-spore-forming control, the Gram-negative soil bacterium Rhizobium sp. NGR234. On sand B. megaterium quickly developed spores, which survived for extended periods and even though the numbers of NGR234 steadily declined, they were still considerable after months of incubation. Thus, microbes that adhere to Saharan dust can live for centuries and easily survive transport across the Atlantic. [source] Analysis of dust pollution in slate and granite transformation plantsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2007Celestino Ordóńez Abstract The production of dust in natural stone transformation plants causes respiratory illnesses in workers that, over time, may seriously affect their physical health. In this article we study dust contamination in a number of ornamental slate and granite transformation plants located in Galicia, in northwest Spain. Using dust concentration measures combined with other factors that increase or decrease the noxious effects of dust (noise, duration over time, etc.), and applying multivariate and geostatistical techniques, we were able to construct dust concentration and associated environmental impact maps. The results were integrated in a GIS (Geographical Information System), which allows us to view the contamination maps, as also information on the machinery used, the associated work stations, the most contaminated areas of each plant, etc. This information was then used to analyze the problem in each plant and to compare results between plants. We propose a method designed to reduce worker exposure to dust using an individualised dust capture system at each of the work stations. The pollution control system and its characteristics were finally incorporated into the GIS to allow interested parties such as the managers of the plants studied or people interested in designing a new plant to consult the available information. © 2007 American Institute of Chemical Engineers Environ Prog, 2007. [source] Eliminating a sulfuric acid mist plume from a wet caustic scrubber on a petroleum coke calcinerENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2001Charles A. Brown Reducing sulfuric acid mist emissions and eliminating the visible plume that remained after steam dissipation were the objectives of a project recently completed for a petroleum coke calciner. The coke calciner produces flue gas containing SO2 that is treated with a wet caustic scrubber. The scrubber is extremely efficient at removing most of the SO2, but some oxidizes to SO3, catalyzed by vanadium in the coke dust that collects in the waste heat boiler. Submicron droplets of H2SO4 form when the flue gas is quenched by the scrubber liquor, and makes its way through the scrubber. This paper describes the installation of, and performance test results for, a wet electrostatic precipitator (WESP), as well as SO2 scrubber modifications that were re q u i red to make room for the WESP. The successful project significantly reduced sulfuric acid mist emissions, eliminating the visible plume while maintaining a very low SO2 outlet concentration, even after removing one of three gas-liquid contactors. [source] Agricultural soils spiked with copper mine wastes and copper concentrate: Implications for copper bioavailability and bioaccumulation,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Rosanna Ginocchio Abstract A better understanding of exposure to and effects of copper-rich pollutants in soils is required for accurate environmental risk assessment of copper. A greenhouse experiment was conducted to study copper bioavailability and bioaccumulation in agricultural soils spiked with different types of copper-rich mine solid wastes (copper ore, tailing sand, smelter dust, and smelter slag) and copper concentrate. A copper salt (copper sulfate, CuSO4) that frequently is used to assess soil copper bioavailability and phytotoxicity also was included for comparison. Results showed that smelter dust, tailing sand, and CuSO4 are more likely to be bioavailable and, thus, toxic to plants compared with smelter slag, concentrate, and ore at equivalent total copper concentrations. Differences may be explained by intrinsic differences in copper solubilization from the source materials, but also by their capability to decrease soil pH (confounding effect). The copper toxicity and bioaccumulation in plants also varied according to soil physicochemical characteristics (e.g., pH and total organic carbon) and the available levels of plant nutrients, such as nitrogen, phosphorus, and potassium. Chemistry/mineralogy of mine materials, soil/pore-water chemistry, and plant physiological status thus should be integrated for building adequate models to predict phytotoxicity and environmental risk of copper. [source] Apportionment of polycyclic aromatic hydrocarbon sources in lower Fox River, USA, sediments by a chemical mass balance modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Ming-Chien Su Abstract Four sediment cores were collected from the lower Fox River, Wisconsin, USA, to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) using a chemical mass balance model. The cores, which were obtained in 1995 from areas close to Green Bay, Wisconsin, USA, had total PAH concentrations between 19.3 and 0.34 ppm. To determine historical trends of PAH inputs, 210Pb and 137Cs dating was used, and elemental carbon particle analysis was done to characterize particles from the combustion of coal, wood, and petroleum. Source fingerprints were taken from the literature. Our results indicate that coke oven emissions, highway dust, coal gasification, and wood burning are likely sources of PAHs in the lower Fox River. Coke oven emissions are in the range of 40 to 90% of total PAHs, and this fraction decreases from 1930 to 1990, except in core Fox River,A (FR-A). The overall highway dust (HWY) contribution is between 10 and 75%, and this fraction increases from 1930 to present, except in core FR-A. The wood burning (WB) contribution (i.e., wood burning or coal gasification) is less than 7% in cores FR-B, FR-C, and FR-D. In core FR-A, a maximum (,23%) is found around 1960. The contribution of wood burning has changed from less than 6% in 1950 to between 3 and 10% in 1995. Evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene, with a half-life of approximately 0.5 years has been found at the site of core FR-D, which is the shallowest (1.1 m) of the four core sites. [source] | |||||||||||||||||||||||||||||||