Pollutant plume

Wind speed has velocity components in all directions so that there are vertical motions as well as horizontal ones. These random motions of widely different scales and periods are essentially responsible for the movement and diffusion of pollutants about the mean downwind path. These motions can be considered atmospheric turbulence. If the scale of a turbulent motion (i.e., the size of an eddy) is larger than the size of the pollutant plume in its vicinity, the eddy will move that portion of the plume. If an eddy is smaller than the plume, its effect will be to difhise or spread out the plume. This diffusion caused by eddy motion is widely variable in the atmosphere, blit even when the effect of this diffusion is least, it is in the vicinity of three orders of magnitude greater than diffusion by molecular action alone. 

Prior to the onset of rain at the rate of 2.5 mm h, the average concentration of 10-/i,m particles in a pollutant plume is 80 p,g m What is the average concentration after 30 min of rain at this rate ... 

Hay and Pasquill (5) and Cramer (6, 7) have suggested the use of fluctuation statistics from fixed wind systems to estimate the dispersion taking place within pollutant plumes over finite release times. The equation used for calculating the variance of the bearings (azimuth) from the point of release of the particles, cTp, at a particular downwind location is... 

Gaussian techniques, discussed in Chapter 19, are reasonable for estimates of concentrations of nonreative pollutants within 20 km of point sources. It is preferable to utilize on-site wind fluctuation measurements to estimate the horizontal and vertical spreading of a pollutant plume released from a point source. 

Geostatistical techniques, such as variography and kriging, have been recently introduced into the environmental sciences (O Although kriging allows mapping of the pollution plume with qualification of the estimation variance, it falls short of providing a truly risk-qualified estimate of the spatial distribution of pollutants. 

Experimental data can be used to compute the diffusion coefficient based on Fig. 7 as a function of PV for a particular depth of soil, or as a function of depth. One should recognize the importance of the determination of D values in relation to elapsed time and distance from pollutant source. In many instances, the prediction of the advance of a pollutant plume and rate can be very sensitive to the specification of the D coefficient. 

Substantial research on environmental pollution plume persistence and dispersion in air has produced a classification system called Pasquill s stability classes for plume stability in air. Unfortunately, the system does not apply as directly as we might wish since it applies at the much larger scale of stack exhausts and the like. However, some insight from the system is available. 

Figure 7. Industrial Pollution Plume of N02 above Europe, America and Asia average value for 1997.

N. Atlantic (Marine) N. Atlantic (Cont.) Sargasso Sea G. of Mexico (Marine) G. of Mexico (Cont.) Tropical Atlantic Atlantic Pollut. Plume Bermuda Southern Ocean NE Pacific Bahamas Gulf of Mexico Remote Caribbean W. Atlantic Gulf of Maine... 

Similar vertical profiles have been reported in subsequent aircraft studies. Luria et al. (2Q) measured DMS concentrations over the Gulf of Mexico averaging 27 ppt in the marine boundary layer, 7 ppt in boundary layer of continental origin, and <3 ppt in the free troposphere. Van Valin et al. (16) reported highly variable DMS levels over the north Atlantic Ocean in the pollutant plume from the Northeastern U.S., measured in the vicinity of Boston. Those workers also reported a vertical profile from Bermuda which was virtually identical to the stable case of Ferek et al. (15) off Barbados. 

The <5180 data have been used by the researchers to calculate the percentage of leachate water in each well, summed up in a map of the pollution plume (Fig. 16.19). The correlation between the isotopic data and dissolved ions has been checked in Fig. 16.20. Good positive correlations are observed between Cl, COD, and rilxO, and almost no correlation is seen with NH4 and S04. This supports the conclusion that Cl and COD (as well as <5180 and <5D) were conservative tracers. 

Fig. 16.19 Pollution plume, outlined by d180, landfill site, Frankfurt am Main. (From Fritz et al., 1976.)...

In general, the Eulerian scheme (version 4) produced much wider horizontal spread than the Lagrangian (Fig. 20.4), despite the higher concentration peaks. Runs with both meteorological drivers showed the sulphate polluted plume over Varrio, but with about 5-h delay compared to both measurements and Lagrangian (HIRLAM data) run. 

The presence of a mixture of contaminants in the landfill body affects the overall behavior of the pollution plume, and the interaction between various contaminants. The natural setting of landfills is crucial for understanding the biogeochemistry of landfill leachate plumes. 

Characterization of redox environments in pollution plumes has been reviewed by Christensen et al. (2000b). A range of different approaches have been used in addressing redox conditions in pollution plumes ... 

Brun A., Engesgaard P., Christensen T. H., and Rosbjerg D. (2002) Modelling of transport and biogeochemical processes in pollution plumes Vejen Landfill, Denmark. J. Hydrol. 256, 228-248. 

Jensen D. L., Boddum J. K., Redemann S., and Christensen T. H. (1998) Speciation of dissolved iron(ll) and manga-nese(ll) in a groundwater pollution plume. Environ. Sci Technol 32, 2657-2664. 

Lyngkilde J. and Christensen T. H. (1992a) Fate of organic contaminants in the redox zones of a landhll leachate pollution plume (Vejen, Denmark). J. Contamin. Hydrol. 10, 291-307. 

At what rate must well A be pumped to capture all the pollutant plume from the landfill Natural gradient is 0.001 from north to south, aquifer hydraulic conductivity is 10-4 m/sec, and aquifer thickness is 10 m. 

Chemical transport and transformation have been a part of environmental science and engineering for decades. Air pollutant plume dispersion modeling and surface water quality stream modeling are mature elements of EC, commonly termed chemical fate and... 

Hydrodynamic Dispersion Due to the tortuousity of groundwater flowlines, which is linked to the irregulai- geometiy of both primary and secondary aquifer pore space, the pollution plume tends to spread out and dilute in the tliree-dimensional space as it moves downstream. This dispersion can contribute either to acceleration or delay of pollution transfer. 

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