Downwind measurements

Drift From the Chalk Point Natural Drift Brackish Water Cooling Tower Source Definition, Downwind Measurements, Transport Modeling... 

The D2-Puff model, and other plume dispersion models, can be calibrated for the effects of complex terrain at specific sites by experimental releases and downwind measurements of an inert gaseous bacer under a variety of representative meteorological conditions. These calibrations can significantly enhance the accuracy of dispersion calculations from specific fixed sites like chemical agent storage yards and demilitarization facilities. 

Despite these limitations, mobile monitoring systems have been used to obtain useful information, such as the verification and tracking of the St. Louis, Missouri, urban plume. The measurement of a well-defined urban plume spreading northeastward from St. Louis is shown in Fig. 15-2 (7). These data were collected by a combination of instrumented aircraft and mobile vans. Cross-sectional paths were flown by the aircraft at increasing distances downwind. Meteorological conditions of low wind speed in the same direction helped to maintain this urban plume in a well-defined... 

For a tracer release that can be considered to be at ground level, approximate the vertical dispersion cr at the downwind distance where measurements indicate that the concentra-... 

An estimate is required of the total hydrocarbon concentration 300 meters downwind of an expressway on an overcast day with wind speed 4 m/s. Tlie expressway runs norlli-south and the wind is from tlie west. Tlie measured traffic flow is 8000 vehicles per hour during tlris rush hour, and the average speed of the velucles is 40 mph. At tlris speed tlie average vehicle is expected to... 

Highly toxic release warrants die evacuation of persons in vulnerable zones downwind of the release. Releases of lesser toxicity may allow for other measures to be taken to minimize exposure, such as advising for persons to remain indoors. 

All distances were measured from the downwind edge of the effective swath located on the downwind side of the application zone. 

Free dunes have no fixed position, but migrate downwind by erosion on the gently inclined windward side and deposition on the leeward side (slip face) in the same way as described for fixed dunes. The smallest free dunes are common wind ripples that measure only a few centimeters in height. Large dunes are found in extensive dune areas in deserts, in sand seas known as ergs . 

Air samples collected in one acrylonitrile-fiber plant ranged from 3 to 20 mg/m3 (EPA 1980a). Mean 24-hour acrylonitrile concentrations in atmospheric samples collected within 5 km of 11 factories producing or using acrylonitrile ranged from less than 0.1 to 325 pg/m (Suta 1979). The occurrence of acrylonitrile was correlated to wind patterns the highest concentrations were downwind of and in close proximity to the plant. The median concentration of acrylonitrile for 43 measurements in "source-dominated areas" (i.e., near chemical plants) was 2.1 pg/m (Brodzinsky and Sing 1983). There were no data available on the concentration of acrylonitrile in air near chemical waste sites, but because acrylonitrile is easily volatilized, this is an exposure pathway of concern. 

A trash incinerator has an effective stack height of 100 m. On a sunny day with a 2 m/s wind the concentration of sulfur dioxide 200 m directly downwind is measured at 5.0 X 10-5 g/m3. Estimate the mass release rate (in g/s) of sulfur dioxide from this stack. Also estimate the maximum sulfur dioxide concentration expected on the ground and its location downwind from the stack. 

From equation (3.13) we can deduct a rough approximation of the location where maximum ground-level concentration occurs. It is argued that the turbulent diffusion acts more and more on the emitted substances, when the distance from the point source increases therefore the downwind distance dependency of the diffusion coefficients is done afterwards. If we drop this dependency, equation (3.13) leads to xmax=34,4 m for AK=I (curve a) and xmax=87,7 m for AK=V (curve b), what is demonstrated in fig n The interpolated ranges of measured values are lined in. Curve a overestimates the nondimensional concentration maximum, but its location seems to be correct. In the case of curve b the situation is inverted. Curve c is calculated with the data of AK=II. The decay of the nondimensional concentration is predicted well behind the maximum. Curve d is produced with F—12,1, f=0,069, G=0,04 and g=l,088. The ascent of concentration is acceptable, but that is all, because there is no explanation of plausibility how to alter the diffusivity parameters. Therefore it must be our aim to find a suitable correction in connection with the meteorological input data. 

The strength of the odour was estimated by a number of outdoor observers, who compared the odour with a standard reference of pyridine, and by observers sitting in the KI s mobile laboratory who measured the odour in the ambient air. The observers made the determinations at distances ranging from 50 to 400 metres downwind of the manured field. Fig. 4. 

Our first cotton dust measurements were made in 1967 when one of the authors of this paper measured the ambient dust concentrations downwind from three Mississippi cotton gins (4). 

Descriptions of field studies of power-plant stack plumes were given by Davis et al. The ozone concentration appears to be lower in regions of high sulfur dioxide content. At 32 km downwind from the stacks, it was claimed that the ozone concentration in the plume (now 11 km wide) is higher than the ambient concentration ( 0.08 ppm) by approximately 0.02 ppm. Simultaneous measurements of nitric oxide and nitrogen dioxide were integrated across the plume. Values of the ratio of nitric... 

In addition to observations in Los Angeles, Blumenthal and White have reported measurements of a power-plant plume and an urban plume 35 and 46 km downwind from St. Louis, Nfissouri. Bgute 4-25 shows the evidence of extensive ozone buildup in the urban plume. Simultaneous measurements of scattering coefficient, 6>cat, trace the spread and dilution of suspended particulate material. It is interesting that in the urban plume, which spreads to 20 km in width, the ozone increases while the particulate matter decreases this suggests considerable photochemical production at an altitude of 750 m. Contrary to the statements of Davis and co-workers reported above, the power-plant plume causes a decrease, rather than an increase, in ozone. Nitric oxide in the plume reacts with the ozone as it mixes. This is clearly indicated by the distribution of particulate matter, which acts as a tracer. 

FIGURE 4-2S Plume measurements on September 6, 1973. Left, traverse at 750 m above mean sea level (msl) 35 km downwind (SW) of Arch. St. Louis. Missouri. 11 17-11 37 a.m. Right, traverse at 750 m above msl 46 km downwind (SW) of Arch, St. Louis, Missouri, 3 30-3 49 p.m. Reprinted with permission from Blumenthal and White. ... 

The turkey vulture s sense of smell has even been recruited to detect leaks in natural gas pipelines. In 1938, Union Oil Co. injected ethanethiol into gas lines and watched for turkey vultures to appear over leaks (Stager, 1964). The vultures were attracted from up to 61 m altitude and 183 m downwind. To achieve this attraction, a detection threshold of 1 x 10 to 1 x 10 mol/l was necessary. Later, the vulture s detection thresholds were measured and found to be much higher even than that (Smith and Paselk, 1986 see p. 115). It still is not clear what compounds turkey vultures use to detect carcasses and at what concentrations. 

As an indication of the effect of dust storm episodes on the aerosol concentration in the valley, the per cent Increase in the weekly total mass, coarse sulfur, chlorine, silicon, and iron concentration during a dust storm was computed. In addition, the absolute Increase in these quantities was also computed. The results of this analysis are shown in Table II. These data also indicate that a significant increase in aerosol concentration due to suspended lake bed materials occurs as far downwind as Independence. In order to quantify this effect, the sulfur to iron (S/Fe) and chlorine to iron (Cl/Fe) ratio at each site was examined. At Keeler, all the coarse sulfur and iron measured at the sampling site are suspended from the lake bed. At any site... 

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