نتایج جستجو برای: metal dust
تعداد نتایج: 237954 فیلتر نتایج به سال:
Background and Objectives: Implementation of industrial development programs, without considering environmental considerations has caused continuous entrance of pollutants to air. Therefore, the purpose of this study was assessing the ecological risk of some heavy metals in the dust of a number of non-metallic industries and determining the best indices in pollution assessment of Ardakan area. ...
This investigation was performed to provide heavy metal signatures of urban soils, dusts, rainwater and to evaluate potential sources in Arak, Markazi Province. Thirty-one samples of urban soils, 29 dust and16 rainwater samples were collected in Arak city. Then, Pb, Cu, Zn, As and Ni concentrations were determined by using atomic absorption spectrophotometry. Application of discriminant analysi...
This paper examines the allowed amount of IG (intergalactic) dust, which is constrained by extinction and reddening of distant SNe and thermal history of IGM (intergalactic medium) affected by dust photoelectric heating. Based on the observational cosmic star formation history, we find an upper bound of χ, the mass ratio of the IG dust to the total metal in the Universe, as χ . 0.1 for 10Å . a ...
We study the far infrared (60–500 μm) colours of late-type galaxies in the Herschel Reference Survey, a K-band selected, volume limited sample of nearby galaxies. The far infrared colours are correlated with each other, with tighter correlations for the indices that are closer in wavelength. We also compare the different colour indices to various tracers of the physical properties of the target...
Recently Ménard et al. (hereafter MSFR) detected a subtle but systematic change in the mean color of quasars as a function of their projected separation from foreground galaxies, extending to comoving separations of ∼ 10h−1Mpc, which they interpret as a signature of reddening by intergalactic dust. We present theoretical models of this remarkable observation, using smoothed particle hydrodynami...
According to the Machinery Directive 2006/42/EC, one of the essential requirements relating to occupational safety and health hazards is to prevent dust pollution emitted by machinery during the implementation processes. Research on evaluation of emissions from machinery, according to the method of test bench using tracer gases, are currently being conducted in CIOP-PIB. This article presents s...
Estimates of the cosmic star formation rate and of cluster metallicities independently imply that at z ∼< 0.5 the gas in the universe has substantial average metallicity: 1/10 ∼< Z/Z⊙ ∼< 1/3 for Ωgas = 0.05. This metal density probably cannot be contained in known solar-metallicity galaxies of density parameter Ω∗ ≈ 0.004, implying significant enrichment of the intergalactic medium (IGM) by eje...
To investigate the impact of artisanal zinc smelting activities (AZSA) on the distribution and enrichment of trace metal(loid)s in street dust of a small city in Guizhou province, SW China, street dust samples were collected and analyzed for 10 trace metal(loid)s (Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb, and Hg). Meanwhile, the health risks of local resident exposed to street dust were assessed. The...
We study the motion of dust grains into the Intergalactic Medium (IGM) around redshift z = 3, to test the hypothesis that grains can efficiently pollute the gas with metals through sputtering. We use the results available in the literature for radiation-driven dust ejection from galaxies as initial conditions, and follow the motion onward. Via this mechanism, grains are ejected into the IGM wit...
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