Air Quality and Stationary Source Emission Control (1975) / Chapter Skim
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6 The Relationship of Sulfur Oxide Emissions to Sulfur Dioxide and Sulfate Air Quality
6 The Relationship of Sulfur Oxide Emissions to Sulfur Dioxide and Sulfate Air Quality
Pages 233-275
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From page 233... ...
This chapter reviews the relationship between sulfur oxide emissions and ambient air quality levels for sulfur dioxide and Sol. As il lustrated in Figure 6 - 1, the relationship between sulfur oxide emissions and ambient air quality involves several complex processes.
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From page 235... ...
section 1 describes the nationwide SOx emission inventory; included are discussions of past trends and geographical f eatures ~ Section 2 deals with sulf ur dioxide air quality and its relationship to SOx emissions. Section 3 describes present ambient sulfate levels and examines the dependence of ambient sul fate formation on SOx emissions.
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From page 236... ...
on a national basis, more than 75 percent of SOx emissions result from coal and fuel oil combustion in stationary sources, and more than 50 percent of SOx emissions result from fuel combustion in electric power plants alone. Industrial process SOx emissions, mostly from the metallurgical, petroleum, chemical, and mineral industries.
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From page 238... ...
I: : I: : 1 : ii'.
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From page 240... ...
SULFUR DIOXIDE AIR QUALITY Table 6-3 summarizes the present National Ambient Air Quality Standards for sulfur dioxide. Natural background sulfur dioxide levels are well below the air quality standards; measurements indicate that natural background sulfur dioxide concentrations are on the order of 0.5 to 4 ugly {Georgii 1970, Cadie et al.
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From page 241... ...
·o ·~ en o v)
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From page 242... ...
Particularly high urban sulfur dioxide concentrations are found in the industrialized northeast section of the country, As was illustrated in Figure 6-2, the northeast sector has the greatest SOx emission density. The Relationship Between Sulfur Dioxide Air Quality and Emission Levels The relationship between sulfur dioxide air quality and SOx emissions is simple in one sense but complex in another.
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From page 244... ...
In this case, central-c~ty/ground-level air quality will change little in comparison to the total emission increase for the region, i.e., the deterioration in central-city air quality will be considerably less than that which would be predicted by the linear rollback formula . ~ As will be discussed in Section 4, this hypothetical example has some resemblance to recent sulfur dioxide air quality hi story which involves an apparent paradox of increasing national SOx emission trends accompanied by decreasing urban sulfur dioxide concentrations.
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From page 245... ...
However, t should be noted that even remote areas may be significantly inf luenced by long term transport from anthropogenic sources. Man-made SOx emissions, which are presently estimated to be about two~thirds as great as natural emissions on a global basis, are continually oxidized to form sulfate aerosol; these man-made contributions may constitute a signif leant fraction of sulfate measurements in remote areas.
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From page 246... ...
Considerable uncertainty exists concerning the present state of knowledge; models are not now available for accurately relating SOx emissions to atmospheric sulf ate concentrations ~ However the general form of the relationship can be I, ,
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From page 249... ...
Photoc}~i~llv-induced ox cation of sulfur dioxide to sulf ur trioxide with subsequent reactions Yielding sulfuric act d or sulfates. Irradiation of sulfur dioxide, water, and clean air mixtures yields oxidation rates which are too slow to be significant in urban areas, (Buf alini 1 97 1, HEW 1 97 0, Urone et al.
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From page 250... ...
~ As to the dependence of sulf ate on sulf ur dioxide ~ it appears that at low sulfur dioxide concentrations all three of the chemical reaction mechanisms are such that the rate of sulfate production is directly proportional to sulfur dioxide concentrations. For given values of the other relevant parameters and for a given residence time, the amount of sulfate yield would be directly proportional to sulfur dioxide input.
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From page 251... ...
Figure 6-6b is similar to Figure 6-6a except that sulfate levels reduce to a f inite background level when sulfur dioxide emissions are eliminated. Atmospheric data appear to be consistent with the above discussion of the dependence of sulf ate on sulf ur dioxide.
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From page 253... ...
, local SOx sources are much more important, on a per ton basis, than distant SOx sources to local sulfate air quality. This is because high local oxidation rates lead to considerable sulfate production from local SOx emissions.
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From page 254... ...
1974} . MatAematical-meteorological models which can accurately assess the impact of changes in spatial distribution of SOx emissions on sulfate air quality are only in the initial stage of development, (Altshuller 19~74, Mills 1974~.
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From page 255... ...
~ _~ _ _ _: _ _ _ _ ~ .' 1 ; i.,; 1 ~ .. C~ en 200 15OI 100 50, Range Average I l _1 1 it 70 64 66 6u YEAR FIGURE 6-7: Average Sulfur at 32 Urban NASH Stations Primary Standard Dioxide Concentrations \,_ !
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From page 257... ...
During the 1960's, total SOx emissions increased by 45 percent on a nationwide basis. In contrast, urban sulfur dioxide concentrations decreased by about 50 percent while average urban sulfate levels remained constant during this period.
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From page 258... ...
of rot C53 oo ·.
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From page 259... ...
With these f actors in mind, it seems I-; ~;.e to expect that reductions in urban Sox exist Bone could lead to signif icant improvement ire central-city~ground-level sulfur dioxide air quality in spite of an increase in total ~ nationwide SOx emissions. Apparently this Be; what has happened.
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From page 260... ...
Ambient Non-urban Trendy It was suggested above that trends In urban concentrations of sulfur dioxide and sulf ate could be explained by the recent increase in rural, tall stack SOx emissions, accompanied by a concomitant decrease in central-city~groundlevel SOx emissions. In order to further support this hypothesis, it would be useful to examine ambient non-urban sulfur dioxide and sulfate trends.
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From page 261... ...
This increase is qualitatively in agreement with the trends in SOx emissions which were discussed earlier.
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From page 262... ...
2F 1 o _ 7 1 n~tinnS ( 1962-1 970 ~ 1 1 Locations (1965-1970) 1962 1965 1966 1967 1968 1969 1970 AFAR FIGURE 6-9a: Nonurban Sulfate Trends in the Trained States MASH Data, See Appendix A)
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From page 263... ...
. , ~ ~ I: TV ~ _~ A 2¢ ol I i 1970 1962 1964 1966 1~68 YEAR Locations (~;°~ t970} 27 Locations ( 1965~' 9701 FIGURE 6-9b Nonurban Sulfate Tren , .,7.
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From page 264... ...
Mat}~ematical-meteorological models should be utilized to calculate changes in sulfur dioxide air quality due to increased total SOx emissions as well as to shifts in the spatial distribution of those emissions. Alter juts sophisticated meteorological models as slot available f or explaining the effect on sulfate levels due to changes in SOx emissions ~ simplif fed quantitative analyses should be performed for sulfates which take into account local background levels and signif icant features of the spatial distribution of emissions.
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From page 266... ...
Using this range, the forecasted increase in national urban~groundlevel sulfur dioxide concentrations from the projected increase in power plant SOx emissions would be expected to range from near 0, up to 20%. (See Table 6-6)
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From page 267... ...
It is assumed here that this range is appropriate in comparing power plant SOx emissions to SOx emissions from other sources. By accepting this range, by accounting for natural background sulfate concentrations, and by using a linear relationship of ambient sulfate concentrations, to SOx emissions, the forecasted increase in urban sulk fate levels due to the projected doubling of power plant emissions would be +20 percent to +40 percent.
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From page 269... ...
Because of time limitations, only a very approximate estimate of nationwide air quality changes is presented here. This estimate indicates that the expected increase in nationwide urban sulfur dioxide concentrations would be in the range of O percent to 20 percent, while the likely increase in nationwide urban sulfate concentrations would range from 10 percent to 40 percent.
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From page 270... ...
at: 4)
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From page 271... ...
{1 974a) Temporal and Spatial Rem lationships of Sulfates, Total Suspended Particulates, and Sulfur Dioxide, presented at the 67th Annual Meeting of the Air Pollution Control Association, Denver, Colorado, June 9-13.
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From page 272... ...
~'e~Jhuene Mac / 9 ~ Airborne 972, os ngeles ro1 District Technical Services Division Reports.
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From page 274... ...
and S Barr (1973} The Effects of Power Plant Stack Emissions on the Ground Level Sulfur Dioxide Concentrations in an Urban Area, presented at the 66th Annual Meeting of the Air Pollution Control Association, Chicago, June 24-28.
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From page 275... ...
G { 1 97 23 Statement on the New York State Implementation Plan to Achieve Air Quality Standards for the Metropolitan New York Air Quality Control Region.
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