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Monitoring of particulate matter outdoors 总被引:6,自引:0,他引:6
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Measurements of outdoor human exposure to suspended particulate matter (PM) are always constrained by available resources. An effective network design requires tradeoffs between variables measured, the number of sampling locations, sample duration, and sampling frequency. Sampling sites are needed to represent neighborhood and urban spatial scales with minimal influences from nearby sources. Although most PM measurements for determining compliance with standards are taken over 24-h periods every third to sixth day, outdoor human exposure assessment requires measurements taken continuously throughout the day, preferably over durations of 1 h or less. More detailed particle size and chemistry data are also desirable, as smaller size fractions and specific chemicals may be better indicators of adverse health effects than total mass samples. 相似文献
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Source profiles for industrial, mobile, and area sources in the Big Bend Regional Aerosol Visibility and Observational study 总被引:20,自引:0,他引:20
Chow JC Watson JG Kuhns H Etyemezian V Lowenthal DH Crow D Kohl SD Engelbrecht JP Green MC 《Chemosphere》2004,54(2):185-208
Representative PM2.5 and PM10 source emissions were sampled in Texas during the Big Bend Regional Aerosol Visibility and Observa (BRAVO) study. Chemical source profiles for elements, ions, and carbon fractions of 145 samples are reported for paved and unpaved road dust, soil dust, motor vehicle exhaust, vegetative burning, four coal-fired power stations, an oil refinery catalytic cracker, two cement kilns, and residential meat cooking. Several samples were taken from each emitter and source type, and these were averaged by source type, and in source subgroups based on commonality of chemical composition. The standard deviation represents the variability of the chemical mass fractions. BRAVO profiles differed in some respects from profiles measured elsewhere. High calcium abundances in geological dust, high selenium abundances in coal-fired power stations, and high antimony abundances in oil refinery catalytic cracker emissions were found. Abundances of eight thermally evolved carbon fractions [Atmos. Environ. 28 (15) (1994) 2493] differ among combustion sources, and a Monte Carlo simulation demonstrates that these differences are sufficient to differentiate among several carbon-emitters. 相似文献
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J.A. Gillies V. Etyemezian H. Kuhns J.D. McAlpine J. King S. Uppapalli G. Nikolich J. Engelbrecht 《Atmospheric environment (Oxford, England : 1994)》2010,44(8):1043-1053
There is a dearth of information on dust emissions from sources that are unique to U.S. Department of Defense testing and training activities. Dust emissions of PM10 and PM2.5 from low-level rotary-winged aircraft travelling (rotor-blade ≈7 m above ground level) over two types of desert surfaces (i.e., relatively undisturbed desert pavement and disturbed desert soil surface) were characterized at the Yuma Proving Ground (Yuma, AZ) in May 2007. Fugitive emissions are created by the shear stress of the outflow of high speed air created by the rotor-blade. The strength of the emissions was observed to scale primarily as a function of forward travel speed of the aircraft. Speed affects dust emissions in two ways: 1) as speed increases, peak shear stress at the soil surface was observed to decline proportionally, and 2) as the helicopter's forward speed increases its residence time over any location on the surface diminishes, so the time the downward rotor-generated flow is acting upon that surface must also decrease. The state of the surface over which the travel occurs also affects the scale of the emissions. The disturbed desert test surface produced approximately an order of magnitude greater emission than the undisturbed surface. Based on the measured emission rates for the test aircraft and the established scaling relationships, a rotary-winged aircraft similar to the test aircraft traveling 30 km h?1 over the disturbed surface would need to travel 4 km to produce emissions equivalent to one kilometer of travel by a light wheeled military vehicle also traveling at 30 km h?1 on an unpaved road. As rotary-winged aircraft activity is substantially less than that of off-road vehicle military testing and training activities it is likely that this source is small compared to emissions created by ground-based vehicle movements. 相似文献