Dust sources

The primary constituents to be measured are the pH of precipitation, sulfates, nitrates, ammonia, chloride ions, metal ions, phosphates, and specific conductivity. The pH measurements help to establish reliable longterm trends in patterns of acidic precipitation. The sulfate and nitrate information is related to anthropogenic sources where possible. The measurements of chloride ions, metal ions, and phosphates are related to sea spray and wind-blown dust sources. Specific conductivity is related to the level of dissolved salts in precipitation. 

Conveying and sieving enclose potential dust sources, and filter evacuated gases. 

FDM FDM (Fugitive Dust Model) is an air quality model designed for computing concentration and deposition impacts from fugitive dust sources. Click the following filenames to download the file ... 

The final example is shown in Fig. 10.86. Several workers are breaking gates off of castings on the conveyor by hand. Much dust is generated by this operation and the dust rises due to buoyancy. To remove the dust, an exterior hood was placed beside the conveyor and a supply inlet was placed above the workers. The supply airflow is blown toward the breathing zone of the workers and the dust source. In this case, as the workers and the dust source are located within the supply airflow, the airflow functions to supply the workers with clean air and to transport the dust toward the exhaust inlet. The velocity of supply air is relatively low, 1.1 m s , and the exhaust velocity at the hood face is 2.75 m s . The dimensions of the system are indicated in the figure, and the depth of the device is 6.0 m (compare with Sections 10.3.3 and 10.4.6). 

Obviously, each sample in the sampled area contains particles from each source, but in a varying proportion. Some of the samples mainly contain particles from the power station and less from the incinerator. Other samples may contain an equal amount of particles of each source. In general, one can say that the composition x, of any sample i of dust is a linear combination of the two source patterns Sj and S2 given by x, = c, s, + c,2 2. In this expression c, gives the contribution of the first source and the contribution of the second dust source in sample i. For all n samples these contributions can be arranged in a nx2 matrix C giving X = CS where S is the px2 matrix of the source patterns. If the concentration patterns of the... 

The industrial dust deposited in the metropolitan area of Shanghai consisted of high-coercivity (hematite) and low-coercivity (magnetite/maghemite) particles, usually < 10 pm in size. Four different dust sources could be distinguished on the basis of magnetic properties (Shu et al. 2000). Given previously reported links between... 

Iron was chosen as the reference element because its major source is likely to be soil and it is measured with good accuracy and precision by FIXE. Crustal abundances were taken from Mason (21). Enrichment factors greater than 1 indicate an enrichment of that element relative to crustal abundances values less than 1 indicate a depletion. The results of this calculation are shown in Table 4. For this calculation it was assumed that ammonium and nitrate accounted for all aerosol nitrogen. It is seen that Si and Ca are near their crustal abundance, indicating a probable soil dust source. The low EF for Al is probably due to a systematic error in the Al measurement rather than a true depletion. Potassium, although present in small concentrations, is slightly enriched relative to crust. The other fine aerosol species, C, N, S, and Pb are enriched by factors of thousands over their natural crustal abundance, indicating that they are not due to wind-blown dust. 

The figures also show measured abundances in local soil and road dust sources for comparison. Except for Si, the elemental abundances in the aerosol suggest a combination of road and soil sources. The Ca results are important to this observation because only for Ca were the abundances in aerosols consistently less than those in road dust, but greater than those in soil. 

In the United States in 1996, the total emissions of PMI() were 31 X 106 short tons per year, or 28 Tg per year (EPA, 1997). Fugitive dust sources such as unpaved roads make up 90% of the total PM1() emissions. Figure 2.15 shows sources of PM1() in the United States in 1996 split into (a) nonfugitive dust sources ( 10% of the total) and (b) fugitive dust sources (EPA, 1997). 

FIGURE 2.15 Sources of PM, emissions in the United States in 1996 (a) excluding fugitive dust sources transportation sources accounted for 21% of the total, and (b) fugitive dust sources (adapted from EPA, 1997). 

Samples of dust from each of the two dust sources were collected for testing. They were dispersed in an electrolyte and analyzed for size on a volume basis. Model card dust had a mass mean diameter of 3.6 with a geometric standard deviation of 1.6. The cotton dust released by tapping the loaded filter varied from 4.5 to 6.7 urn mass mean diameter with a geometric standard deviation of about 2. All test concentrations were in the range of 0.5 to 1.5 mg/m, which are typical of cotton mill fine dust concentration. 

Middleton NJ, Goudie AS (2001) Saharan dust sources and trajectories. Trans Inst Br GeogrNS 26 165-181... 

Mineral dust sources in urban areas include road dust resuspension and demolition and construction activities. There is no apparent reason why the unknown part should also be higher or lower at urban or rural sites. A possible cause may be the amount of water attached to SIA which appears increased. Hygroscopic salts on particles, like ammonium nitrate and ammonium sulphate in the fine fraction, and sodium nitrate and sodium sulphate in the coarse fraction attract water erroneously, increasing the PM mass. 

The pH of precipitation that has absorbed S02 or sulfates will depend on the other ions present, which can include N03" formed from nitrogen oxide emissions and base cations from various dust sources, as well as HC03 from atmospheric C02 and organic acids from natural sources. Precipitation with pH values below 5.6 (the value for equilibrium with atmospheric C02) is popularly referred to as "acid rain."... 

Since exhaust ventilation depends upon the provision of air movements, near the source of dust production, sufficiently great to convey the dust into the hood we must have information available on the nature of the dust source and the air velocities generated by the hood. The former entails difficulties because processes vary greatly. Some opera-... 

The first step will be dust removal. The influx of dust and other desert debris is a natural consequence of increased access to the tomb. Furthermore, the tomb floor is a reservoir of dust. We have examined the role of dust in the deterioration of mural surfaces (17-21), After the removal of dust, a dust-free, preformed cement, or better still, granite floor should be installed. Parts of the tombs in which paintings are already irretrievably lost must be covered with polished granite slabs to prevent dust generation from these obvious dust sources. Structural consolidation, cleaning of paint layers, and protection can then follow. 

Mahowald, N., et al. (1999). Dust sources and deposition during the last glacial maximum and current climate A comparison of model results with paleodata from ice cores and marine sediments. 

Naiman Z., Quade J., and Patchett P. J. (2000) Isotopic evidence for eolian recycling of pedogenic carbonate and variations in carbonate dust sources throughout the southwest United States. Geochim. Cosmochim. Acta 64, 3099-3109. 

Mahowald N., Kohfeld K., Hannson M., BaUcanski Y., Harrison S. P., Prentice I. C., Schulz M., and Rodhe H. (1999) Dust sources during the last glacial maximum and current climate a comparison of model results with paleodata from ice cores and marine sediments. J. Geophys. Res. 104, 15895-15916. 

Reheis M. C., Budahn J. R., and Lamothe P. J. (2002) Geochemcial evidence for diversity of dust sources in the Southwestern US. Geochim. Cosmochim. Acta 66, 1569-1587. 

Investigations of Fugitive Dust Sources, Emissions, and Controls, pre-... 

Claquin T, Schulz M, Balkanski YJ (1999) Modeling the mineralogy of atmospheric dust sources. 

Ignition source energy of 10 to 1000 mj or as low as 5 mj for highly explosive dust sources... 

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