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Atmospheric air pollution turbulent fluxes can be assumed to be proportional to the mean concentration gradient. This assumption,
along with the equation of continuity, leads to the advection-diffusion equation. Moreover, large eddies are able to mix scalar
quantities in a manner that is counter to the local gradient. We present a general solution of a two-dimension steady state
advection-diffusion equation, considering non-local turbulence closure using the General Integral Laplace Transform Technique.
We show some examples of applications of the new solution with different vertical diffusion parameterisations. 相似文献
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Tiziano Tirabassi Alessandro Tiesi Daniela Buske Marco T. Vilhena Davidson M. Moreira 《Atmospheric environment (Oxford, England : 1994)》2009,43(13):2221-2227
The moments of the concentration distribution obtained using a recent analytical solution of the steady-state two-dimensional advection–diffusion equation are presented. The solving methodology is the Generalized Integral Laplace Transform Technique, which allows obtaining a reliable solution of the advection–diffusion equation without any restrictive assumption about the eddy diffusivity coefficients and wind speed profiles. The first four moments and value and position of maximum ground level concentration are calculated. The concentration standard deviation is compared against the semi-empirical ones used in operative Gaussian models. 相似文献
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Antonio G. Goulart Davidson M. Moreira Marco T. Vilhena Gervásio A. Degrazia Sergej S. Zilitinkevich 《Environmental Fluid Mechanics》2007,7(5):409-419
Starting from the evolution equation for the turbulent energy density spectrum (EDS), we develop a new model for the growth
of the Convective boundary layer (CBL). We apply dimensional analysis to parameterize the unknown inertial transport and convective
source term in the dynamic equation for the three-dimensional (3-D) spectrum and solve the 3-D EDS equation. The one-dimensional
vertical spectrum is derived from the 3-D spectrum, employing a weight function. This allows us to select the magnitude of
the vertical spectral component for the construction of the growing 3-D EDS. Furthermore, we employ the vertical component
of the energy spectrum to calculate the eddy diffusivity (required in dispersion models). Currently there are no available
experimental data to directly verify our EDS model. 相似文献
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D.M. Moreira T. Tirabassi M.T. Vilhena A.G. Goulart 《Atmospheric environment (Oxford, England : 1994)》2010,44(15):1859-1865
This paper presents a semi-analytical solution for the steady advection–diffusion equation that allows simulating the vertical turbulent dispersion of air pollution with deposition to the ground. The performances of the solution, with a proper parameterization of the vertical profiles of wind and eddy diffusivity, were evaluated against Hanford diffusion experiment dataset using two tracers (Doran and Horst, 1985): a non-depositing gas (SF6) and depositing particles (ZnS). Results show that the dispersion model with the K-parameterization included produces a good fitting of the measured ground-level concentration data and there are no big differences between the parameterizations taken from literature. A comparison with other models was shown and discussed. 相似文献
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Maria S. P. Vilhena Marcondes L. Costa Jose Francisco Berredo 《Environmental geochemistry and health》2013,35(4):477-494
The high consumption of crabs (Ucides cordatus) stimulated interest in the present study on the northern coast of Brazil, which encompasses a preserved area of mangrove forest. The objective was to describe and quantify the transfer of metals from the muddy sediments to the leaves of the Rhizophora mangle, and thence the crabs and humans. The samples were collected along two transects, while samples of hair were obtained from local habitants. The pH, interstitial salinity, Eh (mV) were measured, the granulometry and mineralogical and multi-element chemical analyses were run, and the organic material determined. The sediments are silty-clayey, composed of quartz, kaolinite, iron oxides, and illite, as well as smaller portions of smectite, pyrite, halite, and high levels of SiO2 (56.5 %), Al2O3 (18.5 %), and Fe2O3 (7 %). The elements Zn, Sr, As, and Zr are concentrated in the leaves, while the bioaccumulation of Zn, Se, Sr, and As was recorded in the crabs, of which, Se is the most concentrated in the tissue of the muscles and the hepatopancreas. The concentrations of nutrient and toxic elements were similar in all age groups (hair samples), with only Hg presenting an increasing concentration between infants and adults. The highest rates of transfer were recorded for the elements Zn and Se in the crabs and Hg in leaves and hair. The accumulation of metals in the leaves and crabs reflects the chemical composition of the sediments and low rates of sediment-vegetation-crab transfer, with the exception of Hg, which accumulated in the hair. 相似文献
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