224,223 research outputs found

    PARTICULATE MATTER IN ATMOSPHERIC AIR IN URBAN AGGLOMERATION

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    Forecasting Particulate Matter Concentrations: Use of Unorganized Machines

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    Air pollution is an environmental issue studied worldwide, as it has serious impacts on human health. Therefore, forecasting its concentration is of great importance. Then, this study presents an analysis comprising the appliance of Unorganized Machines – Extreme Learning Machines (ELM) and Echo State Networks (ESN) aiming to predict particulate matter with aerodynamic diameter less than 2.5 m (PM2.5) and less than 10 m (PM10). The databases were from Kallio and Vallilla stations in Helsinki, Finland. The computational results showed that the ELM presented best results to PM2.5, while the ESN achieved the best performance to PM10

    Fine particulate capture device

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    To capture fine particulate matter in a gas such as air, a dielectric fluid is directed to the center of whichever face of a rotating disc is exposed to the air flow. The disc is comprised of two or more segments which bear opposite electrostatic potentials. As the dielectric fluid is centrifuged towards the periphery of the rotating disc, the fluid becomes charged to the same potential as the segment over which it is passing. Particulate matter is attracted to the charged segment and is captured by the fluid. The fluid then carries the captured particulate matter to a collection device such as a toroidal container disposed around the periphery of the disc. A grounded electrically-conductive ring may be disposed at the outer periphery of the disc to neutralize the captured particles and the fluid before they enter the container

    Quantitative relations between biomass and organic/inorganic resuspended particulate matter

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    During a period of two years, organic and inorganic suspended particulate matter and phytoplankton biomass was frequently measured in Lake Erken, a moderately deep, eutrophic lake in south-eastern Sweden. Regression analyses of these data were used to differentiate and quantify newly produced planktonic particulate matter (zooplankton + phytoplankton + bacteria) and different types of resuspended particulate matter (organic, inorganic). Resuspended particulate matter was frequently dominant in the water column (yearly mean 59% of suspended particulate matter), and resuspended particulate organic matter ranged from 11 to 99% of suspended particulate organic matter (yearly mean: 40%). The high amount of resuspended particulate matter originates from erosion/transportation bottoms which are located at water depths above 16 m and which cover 93% of the lake area. Resuspended particulate matter was significantly related to diatom biomass but not to any other type of planktonic biomass. Consequently, the seasonal variations in the amount and distribution of diatoms can be explained by the hydrodynamic processes which affect the amount and distribution of resuspended particulate matter while seasonal variations in the amount and distribution of other planktonic biomass need further explanations, like active swimming, floating and grazing resistance

    A summer time series of particulate carbon in the air and snow at Summit, Greenland

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    Carbonaceous particulate matter is ubiquitous in the lower atmosphere, produced by natural and anthropogenic sources and transported to distant regions, including the pristine and climate-sensitive Greenland Ice Sheet. During the summer of 2006, ambient particulate carbonaceous compounds were characterized on the Greenland Ice Sheet, including the measurement of particulate organic (OC) and elemental (EC) carbon, particulate water-soluble organic carbon (WSOC), particulate absorption coefficient (σap), and particle size-resolved number concentration (PM0.1–1.0). Additionally, parallel ∼50-day time series of water-soluble organic carbon (WSOC), water-insoluble organic carbon (WIOC), and elemental carbon (EC) were quantified at time increments of 4–24 h in the surface snow. Measurement of atmospheric particulate carbon found WSOC (average of 52 ng m−3) to constitute a major fraction of particulate OC (average of 56 ng m−3), suggesting that atmospheric organic compounds reaching the Greenland Ice Sheet in summer are highly oxidized. Atmospheric EC (average of 7 ng m−3) was well-correlated with σap (r = 0.95) and the calculated mass-absorption cross-section (average of 24 m2 g−1) appears to be similar to that measured using identical techniques in an urban environment in the United States. Comparing surface snow to atmospheric particulate matter concentrations, it appears the snow has a much higher OC (WSOC+WIOC) to EC ratio (205:1) than air (10:1), suggesting that snow is additionally influenced by water-soluble gas-phase compounds. Finally, the higher-frequency (every 4–6 h) sampling of snow-phase WSOC revealed significant loss (40–54%) of related organic compounds in surface snow within 8 h of wet deposition

    Levels of heavy metals composition in atmospheric aerosol samples and the influence of african episodes

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    Particulate matter pollution is a serious environmental issue mainly due to the presence of toxic substances and trace metals in the atmosphere from a variety of pollution emission sources. Information about aerosol composition and their sources especially during pollution events can be further used to establish strategies for the reduction of particulate matter concentration. The objective in the present study was to analyse variations in total suspended particle (TSP) mass concentration and heavy metal components for evaluating the atmospheric loadings of substances with different sources as well as to further examine the relationship between the occurrence of African dust intrusions and metallic species concentrations at our coastal station located in South Spain. Non-destructive Wavelength-Dispersive X-Ray Fluorescence (WDXRF) analysis has been applied for the determination of multi-element contents of atmospheric particulate matter.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Airborne particulate matter in spacecraft

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    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization

    Coal and fuel burning effects on the atmosphere as mediated by the atmospheric electric field and galactic cosmic rays flux

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    Abstract: Emissions into the atmosphere of Greenhouse Gases (GHGs) and particulate matter resulting from fossil fuel burning are considered to be the main anthropogenic forcing on the global climate. We show here that the external cyclic influences of cosmic origin that modulate the earth’s climate may either reinforce or mitigate the ‘local’ terrestrial forcings. Among the external influences is cosmic radiation, whose intensity shows a cyclic variation of 11 years, accompanying the 11-year cycle of solar activity. We put forward a mechanism to explain how the emission of particulate matter into the atmosphere might influence global lightning activity. With respect to global lightning activity, we show why, during the 11-year cycle, the influence of an increase in particulate matter concentration in the atmosphere may be negligible in some years, while it will be reinforced in other years, depending on the place of the years in the cycle. We also remark that the effect on global warming of fossil fuel burning is also modulated by the cosmic ray flux, whose influence is mediated by the variation that it promotes on the cloud cover
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