Integrated pollutant concentration distribution over area surrounding elevated point source

1996 ◽  
Vol 54 (3-4) ◽  
pp. 213-216
Author(s):  
A. Azzam ◽  
A. B. Mayhoub
Keyword(s):  
Point Source ◽  
Concentration Distribution ◽  
Pollutant Concentration ◽  
Pollutant Concentration Distribution

Advanced mobile-DOAS techniuqes for locating and identifying urban area emission sources

2020 ◽  
Author(s):  
Zhaokun Hu ◽  
Ang Li ◽  
Pinhua Xie
Keyword(s):  
Spatial Distribution ◽  
Concentration Distribution ◽  
Column Density ◽  
High Spatial Resolution ◽  
Scattered Light ◽  
Pollutant Concentration ◽  
Emission Flux ◽  
Vertical Column ◽  
Vertical Column Density ◽  
Pollutant Concentration Distribution

<p>Pollutant concentration distribution and emission are important ways to understand regional pollution. To investigate the distribution characteristics and identify individual sources rapidly, a new mobile passive differential optical absorption spectroscopy (DOAS) instrument has been developed, which set two angle telescopes (90°,30°) to receive the scattered light respectively, and set two mechanical shutters to switch the optical path quickly in the mobile platform. The instrument collected the zenith scattered light in the UV or visible region and it was used to derive the vertical column density of trace gases above the measurement route. The slant column density in two different viewing directions were detected, and combined with the geometric approximation, the vertical column density of trace gas was obtained. After obtaining the column concentration distribution, the data were analyzed by semi variance analysis combined with geographical information. Monte Carlo simulation was used to reconstruct the high spatial resolution pollutant concentration distribution, combined the wind field data during the observation, the high spatial resolution emission flux in the area can be quickly obtained. A field experiment was performed in Beijing and some industrial area. The distribution information of vertical column density along the route in Beijing was derived, the concentration distribution of NO<sub>2</sub> at 200m *200m resolution and the 0.01° *0.01°resolution emission flux data are obtained further. The new mobile multi light DOAS instrument were operated on a car. The NO<sub>2</sub> column density spatial distribution and the emission flux spatial distribution are obtained with the maximum value of 8.57×1016 molec./cm<sup>2</sup> and 34.8 ug/m<sup>2</sup>/s over the Beijing fifth ring road area. The scheme can provide a new method to verify pollutant concentration distribution and emission inventory.</p>

scholarly journals The Numerical Simulation of Uplifted Street Canyon On Flow Field Structure And Pollutant Diffusion

2021 ◽  
Author(s):  
Mengru Sun ◽  
Yuqing Song ◽  
Changfa Tao ◽  
Xiaoping Liu ◽  
Quanli Wang ◽  
...  
Keyword(s):  
Flow Field ◽  
Street Canyon ◽  
Concentration Distribution ◽  
Field Structure ◽  
Pollutant Concentration ◽  
Windward Side ◽  
Leeward Side ◽  
Building Height ◽  
Lift Height ◽  
Pollutant Concentration Distribution

Abstract The flow field structure, pollutant concentration distribution and dimensionless concentration evolution of uplifted street canyon has been analyzed in this study. Different from the ideal street canyon, the pollutant concentration distribution of the uplifting street canyon is higher at the bottom, lower at the top, higher at the windward side and lower at the leeward side. The total pollutant concentration (TPC) generally decreases with the increase of leeward building lifting height while the lift height increases with the same total building height or the total building height increases with increase in the lifting height. It is beneficial to the pollutant emission of in street canyon. On the contrary, the TPC increases when the total building height increases with the same lift height. The main reason is that the vertical length of the vortex increases, which is more difficult for pollutants to be discharged from the street canyon.

Uniform Horizontal Groundwater Flow against Dispersion in a Shallow Aquifer: Two Analytical Models

1992 ◽  
Vol 23 (1) ◽  
pp. 1-12
Author(s):  
Ram Raj Vinda ◽  
Raja Ram Yadava ◽  
Naveen Kumar
Keyword(s):  
Point Source ◽  
Groundwater Flow ◽  
Cross Section ◽  
Analytical Solutions ◽  
Concentration Distribution ◽  
Analytical Models ◽  
Shallow Aquifer ◽  
Horizontal Cross Section ◽  
Flow Components ◽  
Reactive Pollutant

Analytical solutions converging rapidly at large and small values of times have been obtained for two mathematical models which describe the concentration distribution of a non reactive pollutant from a point source against the flow in a horizontal cross-section of a finite saturated shallow aquifer possessing uniform horizontal groundwater flow. Zero concentration or the conditions in which the flux across the extreme boundaries are proportional to the respective flow components are applied. The effects of flow and dispersion on concentration distribution are also discussed.

The concentration distribution near a continuous point source in steady homogeneous shear

1992 ◽  
Vol 236 ◽  
pp. 95-110 ◽  
Author(s):  
James D. Bowen ◽  
Keith D. Stolzenbach
Keyword(s):  
Point Source ◽  
Concentration Distribution ◽  
Molecular Diffusion ◽  
Isotropic Turbulence ◽  
Critical Value ◽  
Relative Magnitude ◽  
Approximate Analytical Solutions ◽  
Principal Axes ◽  
Continuous Point ◽  
Instantaneous Source

The concentration distribution resulting from a continuous point source in a fluid with a steady linear variation in velocity is distorted by the flow at distances greater than (K/Eb)½, where K is the molecular diffusion coefficient and Eb is a characteristic shear rate. The distribution has two distinct shapes depending on the number of principal axes of fluid strain that are expansive and the relative magnitude of irrotational and rotational shears. For irrotational flows a single expansive principal axis of strain results in a tube-like distribution, while two expansive axes results in a disk-like distribution. Approximate analytical solutions, derived by neglecting diffusion along the expansive axes, agree well with concentrations calculated by numerically convolving the exact instantaneous source solution. The effect of fluid vorticity is generally to reorient the distribution away from the principal axes of strain and to reduce the asymmetry of the concentration distribution. Aside from reorientation, the concentration distribution varies little until the vorticity approaches a critical value defined by a kinematic condition for equilibrium orientation in the presence of rotation. For vorticity greater than the critical value, the concentration distribution becomes axisymmetric around the axis of rotation. Application of these results to numerical simulations of isotropic turbulence suggests that tubes are more common than disks and that vorticity exceeds the critical value in at least 25% of the fluid.

Influence of humic substances on the migration of 237Np, 238Pu and 241Am in a weak loess aquifer

2001 ◽  
Vol 89 (6) ◽  
Author(s):  
L. Chunli ◽  
Y. Yuee ◽  
W. Zhiming ◽  
Li Shushen ◽  
G. Zede ◽  
...  
Keyword(s):  
Point Source ◽  
Flow Velocity ◽  
Humic Substances ◽  
Water Flow ◽  
Concentration Distribution ◽  
Plane Source ◽  
Water Flow Velocity

The influence of humic substances on the migration of radionuclidesThe water flow velocity in the point source experimental column and in the plane source experimental column was calculated as 1.15±0.05 cm/d and 1.06±0.05 cm/d, respectively. The concentration distribution of

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

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