2,056 research outputs found

    Size-resolved source apportionment of ambient particles by positive matrix factorization at Gosan background site in East Asia

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    International audienceSize- and time-resolved aerosol samples were collected using an eight-stage Davis rotating unit for monitoring (DRUM) sampler from 29 March to 29 May in 2002 at Gosan, Jeju Island, Korea, which is one of the representative background sites in East Asia. These samples were analyzed using synchrotron X-ray fluorescence for 3-h average concentrations of 19 elements consisting of S, Si, Al, Fe, Ca, Cl, Cu, Zn, Ti, K, Mn, Pb, Ni, V, Se, As, Rb, Cr, Br. The size-resolved data sets were then analyzed using the positive matrix factorization (PMF) technique in order to identify possible sources and estimate their contribution to particulate matter mass. PMF analysis uses the uncertainty of the measured data to provide an optimal weighting. Fifteen sources were resolved in eight size ranges (0.07~12 ?m) and included continental soil, local soil, sea salt, biomass/biofuel burning, coal combustion, oil heating furnace, residual oil fired boiler, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, copper smelter and volcanic emission. PMF analysis of size-resolved source contributions showed that natural sources represented by local soil, sea salt and continental soil contributed about 79% to the predicted primary particulate matter (PM) mass in the coarse size range (1.15~12 ?m). On the other hand, anthropogenic sources such as coal combustion and biomass/biofuel burning contributed about 60% in the fine size range (0.56~2.5 ?m). The diesel vehicle source contributed the most in the ultra-fine size range (0.07~0.56 ?m) and was responsible for about 52% of the primary PM mass

    Size-resolved source apportionment of ambient particles by positive matrix factorization

    No full text
    International audienceSize- and time-resolved aerosol samples were collected using an eight-stage DRUM sampler from 29 March to 29 May in 2002 at Gosan, Jeju Island, Korea, which is one of the representative background sites in East Asia. These samples were analyzed using synchrotron X-ray fluorescence for 3-h average concentrations of 19 elements consisting of S, Si, Al, Fe, Ca, Cl, Cu, Zn, Ti, K, Mn, Pb, Ni, V, Se, As, Rb, Cr, Br. The size-resolved data sets were then analyzed using the positive matrix factorization (PMF) technique in order to identify possible sources and estimate their contribution to particulate matter mass. PMF analysis uses the uncertainty of the measured data to provide an optimal weighting. Fifteen sources were resolved in eight size ranges (0.07?12 µm) and included Chinese aerosol, soil dust, sea salt, biomass burning, coal combustion, oil heating furnace, residual oil-fired boiler, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, copper smelter, and volcano emission. PMF analysis of size-resolved source contributions showed that natural sources represented by soil dust, sea salt and Chinese aerosol contributed about 79% to the predicted primary PM mass in the coarse size range (1.15?12 µm). On the other hand, anthropogenic sources such as coal combustion and biomass burning contributed about 60% in the fine size range (0.56?2.5 µm). The diesel vehicle source contributed the most in the ultra-fine size range (0.07?0.56 µm) and was responsible for about 52% of the primary PM mass

    Genome of the Root-Associated Plant Growth-Promoting Bacterium Variovorax paradoxus Strain EPS

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    Variovorax paradoxus is a ubiquitous betaproteobacterium involved in plant growth promotion, the degradation of xenobiotics, and quorum-quenching activity. The genome of V. paradoxus strain EPS consists of a single circular chromosome of 6,550,056 bp, with a 66.48% G+C content

    Survival in Nuclear Waste, Extreme Resistance, and Potential Applications Gleaned from the Genome Sequence of Kineococcus radiotolerans SRS30216

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    Kineococcus radiotolerans SRS30216 was isolated from a high-level radioactive environment at the Savannah River Site (SRS) and exhibits γ-radiation resistance approaching that of Deinococcus radiodurans. The genome was sequenced by the U.S. Department of Energy's Joint Genome Institute which suggested the existence of three replicons, a 4.76 Mb linear chromosome, a 0.18 Mb linear plasmid, and a 12.92 Kb circular plasmid. Southern hybridization confirmed that the chromosome is linear. The K. radiotolerans genome sequence was examined to learn about the physiology of the organism with regard to ionizing radiation resistance, the potential for bioremediation of nuclear waste, and the dimorphic life cycle. K. radiotolerans may have a unique genetic toolbox for radiation protection as it lacks many of the genes known to confer radiation resistance in D. radiodurans. Additionally, genes involved in the detoxification of reactive oxygen species and the excision repair pathway are overrepresented. K. radiotolerans appears to lack degradation pathways for pervasive soil and groundwater pollutants. However, it can respire on two organic acids found in SRS high-level nuclear waste, formate and oxalate, which promote the survival of cells during prolonged periods of starvation. The dimorphic life cycle involves the production of motile zoospores. The flagellar biosynthesis genes are located on a motility island, though its regulation could not be fully discerned. These results highlight the remarkable ability of K radiotolerans to withstand environmental extremes and suggest that in situ bioremediation of organic complexants from high level radioactive waste may be feasible
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