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OCR for page 48
2
Emissions of Sulfur Dioxide and
Nitrogen Oxides and Trends for
Eastern North America
Rudolf B. Husar
INTRODUCTION
Air pollution is caused when an element or a compound
is removed from its long-term geochemical reservoir and,
with the help of the atmosphere, dispersed and transferred
to another long-term geochemical reservoir. The elements
redistributed in this manner are carbon, sulfur, nitrogen,
and the crustal elements, including metals. Another type
of air pollution occurs when human activities produce and
disperse compounds that are completely foreign to nature,
such as DOT, polychlorinated biphenyls, dioxin, and some
nuclear fission products. The production and fate of
these compounds will not be discussed further in this
chapter.
We continue removing or mining carbon, sulfur, nitro-
gen, and crustal material from the Earth's long-term
reservoir for two purposes: to "produce" energy from the
fossil fuels and to manufacture from extracted minerals
disposable or permanent objects for societal use. Most
pollutants are emitted from the land into the air, with
the atmosphere serving as a medium for dispersion and
chemical reactions during the transport. The atmosphere
redistributes the emitted materials onto the biota, land,
lakes, and oceans. The role of the rivers is primarily
in gathering these materials from the land and trans-
ferring them to their long-term storage in the oceans.
Certain volatile pollutants may also be re-emitted from
land or from lakes.
48
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49
Examples of the Flow Rates of Sulfur and Nitrogen
from Natural Processes and from Human Activities
It is worth considering a few estimates of flow rates
of sulfur and nitrogen from simple back-of-the-envelope
calculations. If all the coal consumed in the United
States over the past century (500 million tons/yr) were
piled into a single mountain, it would occupy 25 cubic
kilometers, i.e., a pyramid with a base area of 6 km x 6
km, 2 km high. Spread over the entire eastern half of
the United States, it would be a layer of about 1-cm
thickness. This means that from a geophysical weathering
perspective, about 150 g m~2 yr~1 of crustal mineral
material currently goes up in smoke, considering only
coal consumption in the eastern United States. By com-
parison, the natural weathering of the Earth's surface
minerals as they are carried by rivers to the oceans is
about 20 g m 2 yr~l. Thus human activities sig-
nificantly enhance the natural redistribution of the
Earth's crustal material over eastern North America.
Over the past 100 years the average emission density
over eastern North America was about 1-2 g sulfur m~2
yr~ . Most of that sulfur returns to the ground some-
where over eastern North America, resulting in an average
sulfur flow of 100 g sulfur m 2 100 yr 1. By comparison,
the total sulfur content of soils is 3-30 g sulfur/m2.
Hence, the yearly sulfur flow through soils from human
activities is comparable to the natural sulfur content of
the soil itself.
It is also instructive to consider the sulfur and
nitrogen flow from a biological perspective: in the
United States, the average daily per capita emission rate
to the atmosphere is roughly 200 g sulfur (400 g sulfur
dioxide) and 100 g nitrogen (300 g nitrogen dioxide).
This is comparable in weight to the daily per capita food
consumption. The sulfur emission rate from anthropogenic
sources in the United States is about 15 x 1012 g sulfur
yr . Distributing these emissions uniformly over the
contiguous United States with an area of 8 x 1012 m2,
we arrive at an average emission density of 2 g sulfur
m~2 yr~l. This is comparable to the density of
sulfur contained and removed yearly from the soil by
harvesting agricultural products, such as corn and wheat
(Beaton et al. 1974).
The biosphere is a thin shell of living matter on the
Earth's surface. It is responsible for a grand-scale
cycling of energy and chemical elements. Functionally,
OCR for page 50
50
this biological cycling is maintained by three groups:
producers, consumers, and decomposers. The producers are
plants and some bacteria capable of producing their own
food photosynthetically or by chemical synthesis. The
consumers are animals that obtain their energy and protein
directly by grazing, feeding on other animals, or both.
The decomposers are fungi and bacteria that decompose the
organic matter of producers and consumers into inorganic
substances that can be reused as food by the producers
they are the recyclers of the biosphere. Nature is
capable of sustaining the producer-consumer-decomposer
cycle indefinitely with the Sun as the energy source.
The smallest such entity that is self-sufficient is an
ecosystem.
Functionally, human activities that perturb the natural
environment can be divided into similar components (Figure
2.1). Producing activities include energy production
(fossil fuels), manufacturing (nonfuel minerals), and
growing food. The consumers are humans and their domestic
animals. Decomposing or recycling activities include
treatment of waste water, recycling of metals, and the
burning of refuse. However, whereas an ecosystem relies
on its decomposers for a complete recycling of its
elements, the system created by human activity lacks such
efficient decomposers. As such, manufactured materials
that are no longer needed and waste by-products of indus-
trial activity are disposed into the physical environment.
The process of adding unwanted material to the environment
is called pollution. The material that is not recycled
is distributed by the atmosphere and the hydrosphere and
delivered to the biological and geochemical receptors.
The above scheme permits a convenient accounting for
the flow of materials in society from the producers to
consumers to the receptors.
;
Pollutant Flow Diagram
The flow of matter from the producers to consumers and
subsequently to the receptors is depicted schematically
in Figure 2.2. Most of the production of potential
pollutants begins with mining, that is, removing a
substance from its long-term geochemical reservoir. The
amount of pollutant mass, Mi, mobilized by mining
(tons/yr) is the production rate Pi (tons/yr) of the
raw material (coal, oil, smelting ore, etc.) multiplied
by the concentration Ci (grams/ton) of the impurity
(sulfur, mercury, lead, etc.): Mi = ciPi.
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51
NATU RAL CH EM ICAL CYCLI NG
Pla nts
External
world
~V'
Animals
Microorga nisms
Producers ~
-
- [ Recyclers
FLOW OF CHEMICALS FROM HUMAN ACTIVITY
_
Mobi I izers
Prod ucers
J
L
External
world
_~.
'_~;;~_
ski.
Emitters
Receptors
Recyclers
FIGURE 2.1 Diagrams of the movement of chemicals and
materials through (top) the natural ecosystem and (bottom)
a system resulting from human activity.
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52
PRODUCERS CONSUMERS RECEPTORS
Mining Combustion Deposition
surface
transfer, s
atmospheric
transfer, ajk
,~ a11~
s33
M U R.
· ·K
mass moved used at received
by producer consumer at receptor
c; - contaminant
concentration
Pj - production
Mj = cjPj U jj = sjjMj R jjk = ajkSiiCiPi
Uj = ~ s jjMj Rjk = ajkU
Uj = ~ SjjCiPi Rk = ~ ajkUj
Rk = ~ ajk ~ s jjCiP
FIGURE 2.2 Schematic illustration of key matrices in the
flow of material from the producer to the consumer to the
receptor.
Matter is transferred from the producer to the consumer
by ground transportation, including railroads, trucks,
and barges. Functionally, surface transport redistributes
the mined substances over a large geographical area. In
principle, every producer, i, may deliver its product to
any consumer, j. Mathematically, this producer-consumer
transfer is characterized by a surface transfer matrix,
Al].
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53
The amount of matter, Uij, originating from producer
i and used at consumer j is sijMi. The total amount
of matter reaching the consumer j is the sum of the
matter produced by all producers multiplied by their
respective surface transfer matrix elements.
The next transfer occurs between the consumer, or
emitter, and the environmental receptors. The consumer
is located where the combustion or smelting occurs, and
the receptor is located where the pollutant falls fol-
lowing its atmospheric transit. Again, in principle all
emitters j can transfer matter through the atmosphere to
all receptors k. Hence, the matter received at receptor
k that originated at consumer (emitter) j, Rjk, is the
product of the use rate Uj times the atmospheric
transfer matrix, a k, from emitter j to receptor k.
The total amount o] matter deposited at receptor k is the
sum of the use rates Uj at each emitter weighted by its
atmospheric transfer matrix element.
the numeric values of the Mi, ci, and si are
discussed in detail; discussion of the atmospheric
transfer matrix ask is beyond the scope of this report.
The emission estimate at any given emission site U
(tons/yr) is calculated as follows: Uj = sijoiPi,
where Pi
In this chapter,
(tons/yr) is the fuel and metals production
rate at a given mining region, ci (weight fraction) is
the concentration of sulfur in fuel and ore, and sij is
a dimensionless transfer matrix element between producer S
and consumers of fuel and ores.
PRODUCTION AND CONSUMPTION OF FUELS AND METALS
Combustion of coal and oil products, along with the
smelting of metals, produces the bulk of the anthropogenic
sulfur and nitrogen emissions to the atmosphere over
North America. The driving force for fuel combustion is
the demand for energy by the different economic sectors.
Energy Demand of the United States
From the turn of the century to the 1970s, U.S. energy
consumption has been characterized by a steady increase
in total consumption and shifts from one fuel to another
(Figure 2.3). From 1850 to about 1880 wood was the
primary energy source. By 1900, and during the first
quarter of this century, rising energy demand was matched
OCR for page 54
oc9
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TERR
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850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 20co
TERR
_ 0~9
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n
~ . 4
0.1
.
FIGURE 2.3 Trend for U.S. fossil fuel consumption since
1850. (a) Consumption by fuel type; (b) fraction of
total energy by fuel type. Data for 1850 to 1880 from
U.S. Bureau of the Census (1975); data from 1880 to 1932
from U.S. Geological Survey, Yearbooks (1880-1932); data
from 1933 to 1980 from U.S. Bureau of Mines, Mineral
Yearbooks (1933-1980).
OCR for page 55
55
by the increasing use of coal. The depression years of
the early 1930s are reflected in the sharp drop of coal
consumption, which increased again during the war years
in the early to mid-1940s. Coal consumption declined to
another minimum in 1960, because the increasing energy
demands were supplied by cleaner fuels, natural gas and
petroleum. Accelerated oil and gas consumption began in
the late 1930s and 1940s, such that by 1950 the energy
supplied by oil exceeded that of coal and maintained its
rise up to the early 1970s. The 1973 oil embargo is
reflected as a small rinole. The second dip, in the late
,, _
1970s and early 1980s, reflects another oil embargo and
reduced industrial activity.
The 1950s and 1960s were the years of strong increase
in natural gas consumption, which by 1960 also surpassed
coal as an energy source. Nuclear energy began to supply
a detectable fraction of the total energy consumption in
the United States only after 1970.
Coal
Reserves and Production
In the United States, coal is mined in three regions:
Appalachia, the Midwest (Interior), and the West. The
coals in the regions differ in quality and concentration
of impurities such as sulfur. The coal production data
used in this chapter were obtained from Mineral Yearbooks
(U.S. Bureau of Mines 1933-1980) and from Mineral
Resources of the United States Yearbooks (U.S. Geological
Survey 1880-1932).
Figure 2.4(a) shows the time-dependent contributions
of the three regions to the national production of coal.
The output of the Appalachian districts spanning
Pennsylvania to Alabama is shown on the lowest curve.
The curve shows that Appalachian production has remained
at about 300 million tons/yr since about 1920. The
second shaded area in Figure 2.4(a) is the contribution
of the Interior region, which includes western Kentucky,
Indiana, Illinois, Missouri, and Texas. The third area,
negligible until around 1970, represents the contribution
from the West. These curves reveal that a major shift in
the coal production occurred at around 1970, when the
production of Western coal became significant. Remark-
ably, within the span of a decade, low-sulfur Western
coal captured a quarter of the United States coal market.
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56
The coal production within the Appalachian region has
also shifted substantially since 1900, as depicted in
Figure 2.4(b). From about 1910 to the early 1920s the
Pennsylvania coal production was about 160 million
tons/yr, which has dropped to about 80 million tons in
the post-World War II period. West Virginia production
peaked during World War II and declined in the late 1960s.
East Kentucky, on the other hand, had low production
rates up to about 1960, and now it exceeds that of
Pennsylvania. Similar trends are shown in the production
data for three districts in the Interior region:
Illinois, Indiana, and western Kentucky (Figure 2.4(c)).
The significance of these shifts to sulfur emissions is
that each coal-producing district has its own range of
sulfur content: a shift in the relative production rate
results in a change of the average sulfur content and
sulfur production. The coal-production data described
above define the raw material production rate Pi shown
in Figure 2.2.
900-
soo -
700 ~
600-
200-
100-
a
U.S. Total ~
,`' West
Get
r— ~
....
I nterio r
....... ,., ~ , ~ , ~ I ~ I ~ I I Tall I ~ I I ~ ~ I I ~
1870 1890 1910 1930 1950 1970 1990
FIGURE 2.4 (a) Coal production in the three U.S. coal-
producing regions: Appalachia, Interior, and West; (b)
trends in Appalachian coal production; (c) trends in
Interior coal production. Data from U.S. Geological
Survey Yearbooks (1880-1932); U.S. Bureau of Mines,
Mineral Yearbooks (1933-1980); Energy Information
Administration, 1983.
OCR for page 57
57
Sulfur Content
The next parameter that will be examined is ci, the
concentration of the contaminant sulfur, for each
coal-producing regione Knowing the production rate P
and concentration ci permits the calculation of the
mass of contaminant, Mi = ciPi, that is mobilized
by each producer.
180 -
170 -
- 180-
150 -
140 -
130 -
120 -
110 -
~oo
90
~o
70
~0
50
40
30
20
10
b
Pennsylvania
~
/
. ~
~ 1
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0~ E. Kentucky
o
1870 1890 1910 1930 1950 1970
~ .... , ' ., .,, .,, , ., , , ,,, .,,, , .,, .,, .,, , , ' .
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80 -
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z
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~ ~
I llinois
~h~^Q' .'
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. =~ tucky
__. .. ............ . . . .
MA
O ~
1870 1890 1910 1930 1950 1970
FIGURE 2.4 (continued).
OCR for page 58
58
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OCR for page 82
82
with those in the 1930s and early 1900s but are substan-
tially below those of the 1920s, 1940s, and 1960s.
The emission trend for the eastern states south of the
Ohio River (Region C) is given in Figure 2.24(d). The
emissions were relatively low in the southeastern United
States until about 1960, when a strong Increase occurred.
This upward trend has persisted into 1980s.
The sulfur emission trend for the industrialized
Midwest (Region D), including Illinois, Indiana, Michigan,
Missouri, and Ohio, is given in Figure 2.24(e). The
emission trend in this region shows a doubling since the
turn of the century with peaks in the 1920s, 1940s, and
1970s and depressions in the 1930s and 1950s.
The sulfur emission trend for the upper Midwest (Region
E)--Iowa, Minnesota, and Wisconsin--is given in Figure
2.24(f). The emissions in this region, currently less
than 1 million tons/yr, have been consistently low over
the last 100 years.
A comparison of sulfur emission densities north and
south of the Ohio River is given in Figure 2.25, expressed
as emission per unit area (g sulfur m~ yr~l).
Emissions north of the Ohio River (Regions A, B. D, and
E) have increased about 33 percent since the 1920s. In
contrast, emissions south of the Ohio River (Region C)
show a threefold increase since the 1930s. Currently,
the sulfur emission densities are comparable for the
regions north and south of the Ohio River.
REGIONAL TRENDS IN EMISSIONS OF NITROGEN OXIDES
Nitrogen oxides constitute the second major source of
acidifying compounds. The overwhelming fraction of
nitrogen oxide emissions arises from the combustion of
fossil fuels; emissions from metal-orocessinq plants are
insignificant.
two important
_
Fuel consumption data constitute one of
inputs needed for estimating nitrogen oxide
emissions. The other is data for nitrogen oxide emission
factors. For a given source of combustion, this factor
is the quantity of nitrogen oxide emitted per unit of
fuel consumed.
Estimating historical emission trends of nitrogen
oxides is difficult because most of the nitrogen oxide is
formed by the fixation of atmospheric nitrogen at high
temperatures of combustion rather than by oxidation of
the nitrogen contained in the fuel. The nitrogen oxide
emissions depend primarily on the combustion temperature
OCR for page 83
83
5 !
-
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Cow
~ 3~
1
Ij\~ North
Elf South
~ \r~
car
or
l
r1~
°~''""''""''''1"'''''''''''''''''1'''''''''''''''''''i'''""''''"''''''1''''''''''''''''''
1880 1900 1920 1940
YEAR
1 96t3 ~ 980 2000
FIGURE 2.25 Sulfur emission densities for regions north
(Regions A, B. D, E) and south (Region C) of the Ohio
River.
and to a lesser degree on fuel properties. Since com-
bustion processes in internal-combustion engines and
boilers have undoubtedly changed since the turn of the
century, it is likely that nitrogen oxide emission factors
also have changed historically. Because combustion
parameters can vary randomly over a wide range, and
because information on historical combustion processes is
generally lacking, assumptions concerning changes in
emission factors over time constitute the major source of
uncertainty in developing trends in nitrogen oxide
emissions.
The emission factors for 1970 to 1980 used in this
chapter were derived from extensive inventories that list
nitrogen oxide emission factors according to source type
of combustion (U.S. Environmental Protection Agency 1977,
1978). The numerous emission factors listed in these
compilations were aggregated into four weighted-average
emission factors by fuel type: coal, gasoline, natural
gas, and other petroleum products. The emission factors
OCR for page 84
84
10
9
0 0
co
of
o
Cat
7
LL
rL 5
LL
o
l
4
Or '
o
/
/
/
/
/ Coal (tons NOX/l 000 ton)
Gasoline (tons NOX/1 000 barrels)
.... .
_—~ 3
Natural Gas (tons NO/100 rnill~on ft )
Other Petroleum (tons NOX/1000 barrels)
1880 1900 1920 1940
YEAR
1 960 1 980 2000
FIGURE 2.26 Trends in emission factors of nitrogen oxide
by fuel type. Emission factors from the period of 1970
to 1980 were derived from data given from the U.S.
Environmental Protection Agency (1977, 1978). For the
period from 1880 to 1970, trends of historical emission
factors were assumed to be linear, with slopes varying by
fuel type.
before 1970 were estimated to reflect the fact that the
average combustion temperature, and hence the production
of nitrogen oxide per unit of fuel consumed, was lower,
especially for coal combustion, over the past 100 years
(Figure 2.26). A simple linear trend was assumed for all
emission factors. For coal combustion the emission
factor was assumed to increase fivefold from 1880 to
1970. For combustion of gasoline and natural gas the
emission factors were assumed to increase by 50 and 100
percent, respectively, during the same period. The
emission factor for other petroleum products was assumed
to be constant over time.
Based on these estimates of emission factors and data
on fuel consumption, regional emission trends were
calculated (Figure 2.27). The shaded areas represent a
range of uncertainty of +30 percent, reflecting the
large uncertainties inherently associated with the
OCR for page 85
85
20 r a
> 18
~x 1 6
z 14
z 12
O 10
O 8
6
4
o 1
9
8
x
0 7
~ 6
0 5
z 4
o 3
J
2
1
o
Eastern United States If
- _~
—C
REGION C
r\,( ,_
~ :
,~ :::1
f ~
~ :~ :~W
9
8
v
1 880 1 900 1 920 1 940 1 960 1 980 2000
YEAR
OR
8
7
6
5
4
_ b
REGION B
3 ,_
2 _ ~~- ~~:
NI~ ~
1 _ ~
O ~—1 1
REGION D
o
f
NOx emission density
North-South
/ r
1~
North of , <~ A/
Ohio River i / South of
~V" ~ Ohio River
O = 1 1
1 880 1 900 1 920 1 940 1 960 1 980 2000
YEAR
FIGURE 2.27 (a) Trends in emissions of nitrogen oxides
in the eastern United States (the aggregate of Regions B.
C, D, and E); (b) Region B; (c) Region C; (d) Region D;
(e) Region E; (f) trends in emission densities of regions
north (Regions B. D, and E) and south (Region C) of the
Ohio River.
assumptions made in these calculations. For the eastern
United States (the aggregate of Regions B. C, D, and E;
Figure 2.27(a)), the estimates indicate a strong
monotonic increase since the late 1800s. Evidently,
there has been no significant change since the mid-1970s.
The nitrogen oxide emission estimates for Region B are
given in Figure 2.27(b). A steady increase is evident
since the turn of the century, leading to a peak in the
late 1970s. The emission trend for states south of the
Ohio River (Region C; Figure 2.27(c)) shows a roughly
OCR for page 86
86
exponential increase since the turn of the century. The
nitrogen oxide emission trend for the industrialized
Midwestern states (Illinois, Indiana, Michigan, Missouri,
and Ohio (Region D)) is shown in Figure 2.27(d). This
trend resembles that of the northeastern states, showing
a roughly linear increase since the 1920s. The upper
Midwestern states (Iowa, Minnesota, and Wisconsin (Region
E)) show a steady upward trend (Figure 2.27(e)). However,
the tonnage of nitrogen oxide emissions is substantially
less than those for the northeastern, southeastern, and
other Midwestern states. A comparison of trends in
nitrogen oxide emission densities north (Regions B. D,
and E) and south (Region C) of the Ohio River is given
Figure 2.27(f). The northern states show a roughly
linear increase since the 1920s, while the growth was
roughly exponential in the Southeast. Currently, the
emission densities in the two regions are almost
equivalent.
COMPARISONS WITH OTHER TREND ESTIMATES
Sulfur Dioxide
The methodology presented in this chapter for
estimating sulfur emission trends is for the most part
similar to other approaches found in the literature.
Emissions estimates are derived from information on the
consumption of fossil fuels and the smelting of metals.
The methodology differs from other reports by the way in
which sulfur content of coal is estimated. The method
described here uses mining data to determine the tonnage
and distribution of the sulfur content in the coal at the
mining site and information on the transport of the coal
to the consumer to determine the emission source. From
such an analysis it is possible to specify the
uncertainty in sulfur emissions based on the sulfur
distribution function of the mined coal.
Recently, an extensive compilation of emissions of
sulfur dioxide and nitrogen oxides was developed by
Gschwandtner et al. (1985). They report yearly
state-by-state emissions estimates in the United States
from 1900 to 1980. The difference between their analysis
and the one presented here is in the method for
calculating the sulfur content of coal in each state and
estimating its uncertainty as a function of time.
OCR for page 87
87
A direct comparison of the results of the two estimates
is shown in Figure 2.28. The shaded areas represent the
estimated range of uncertainty in our analysis, and the
diamonds represent the results of Gschwandtner et al. As
shown in Figure 2.28(a) for the eastern United States
(Regions B. C, D, and E), the estimates agree qualita-
tively over much of the time period since 1900. Both
estimates show peaks in the 1920s and in the early to
mid-1940s. Both show steeply rising emissions in the
1960s and dips in the 1930s and 1950s.
However, the estimates differ in some respects. Until
about 1970 the estimate of Gschwandtner et al. for the
eastern United States is consistently higher than our
estimate. Furthermore, beginning around 1970 the trends
appear to diverge. The estimate of Gschwandtner et al.
shows a decrease in emissions in the eastern United States
that continues through the 1970s. Our estimate suggests
either no change or a possible increase, although the
difference between the two estimates lies within the
range of estimated uncertainty (see the shaded area,
Figure 2.28(a)). A comparison of the emission trends is
shown for three states in Figures 2.28(b)-2.28(d) to
illustrate in more detail the extent of the differences
in the two data sets. For Illinois, our estimate is
substantially below that of Gschwandtner et al., except
for the 1970s; the trend estimates for the state of
Georgia are almost identical; for New York, the two
estimates overlap since the 1930s but deviate before that
time. These differences undoubtedly arise from the
different assumptions employed in deriving the estimates.
Nitrogen Oxides
Gschwandtner et al. (1985) have also developed compr
hensive estimates of emissions of nitrogen oxides. A
comparison of our estimates with theirs is shown in Figure
2.29. Our analysis attempts to account for changes in
emission factors that may have occurred over the past 100
years because of changes in average temperatures of
combustion; the estimates of Gschwandtner et al. did not
attempt such a correction. Nevertheless, as shown in the
figure, after about 1930 the two estimates fall well
within the range of estimated uncertainty, except for the
lower estimates of Gschwandtner et al. for Region B in
the 1970s.
OCR for page 88
88
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OCR for page 89
89
20
18
16
14
12
10
6
4
o
x
o
he
o
of
o
J
CC 9
~ 8
O 7
to 6
O 5
an 4
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A 2
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O
1880 1900 1920 1940 1960 1980 2000
Eastern United States
l ~ r!
~ I/'
1 ,' 1 1 1
1
REGION C
Vent ~~
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-1~ 1
YEAR
9
8
7
6
5
4
1
o
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8
O 7
can 6
O 5
o 3
A 2
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b
REGION B
_ ~
d
REGION D
LO
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1880 1900 1 920 1940 1960 1980 2000
YEAR
FIGURE 2.29 Comparison of estimates in nitrogen oxide
emission trends reported in this chapter with the
estimates of Gschwandtner et al. (1985) (dark lines) for
(a) the eastern United States (Regions B. C, D, and E);
(b) Region B; (c) Region C; (d) Region D.
SUMMARY
Sulfur emission trends for the eastern half of the
United States and southeastern Canada are reconstructed
for the past 100 years (1880-1980).
The approach adopted
uses a sulfur-flow accounting scheme from production in
mines through distribution over land to emission sources.
The average sulfur content of coal consumed in each state
is estimated in this manner. The state-by-state sulfur
emissions are calculated as the product of coal consumed
and the average sulfur content. Coal combustion accounts
for most of the current sulfur emissions, which are
estimated to be between 11 and 15 million tons of
sulfur/yr.
Sulfur mobilization by oil products increased from the
1940s until about the 1960s, when it leveled off at 3 to
4 million tons of sulfur/yr. Since 1978 there has been a
significant reduction of oil sulfur emissions that is
attributed to reduced oil imports and increased sulfur
recycling at refineries.
OCR for page 90
go
The sulfur mobilization from copper and zinc smelting
fluctuated from 0.5 to 1.5 million tons of sulfur/yr
since the turn of the century. These emissions have
dropped significantly since 1970 as a consequence of
reduced sulfur production and increased sulfur recovery.
In eastern North America, sulfur dioxide emissions
showed the most rapid rate of increase in the period from
approximately 1880 to 1910. Since then sulfur emissions
have increased overall by about SO percent, but the
increase has not been monotonic. Rather, the emissions
have fluctuated between peaks and dips as a result of
social, political, and economic factors. The 1920s,
early 1940s, and late 1960s were "peak n periods, whereas
the 1930s and the 1950s were periods of declining
· .
emlss cons .
Eastern North America was divided into five regions
(see Figure 2.23). Until about 1970, emissions in each
of these regions, although differing in magnitude,
exhibited for the most Part similar patterns of peaks and
dips described above for the entire area. After about
1970 strong regional differences in trends of sulfur
dioxide emissions emerged. The most distinctive differ-
ences were between the regions north and south of the
Ohio River. Southeastern Canada (Region A) and the
northeastern United States (Region B) show distinct
downward trends. The southeastern United States (Region
C) exhibits a steeply increasing trend. The midwestern
United States (Region D) shows little change or perhaps a
slightly increasing trend in sulfur dioxide emissions,
and emissions in the north central United States (Region
E) have remained low.
Nitrogen oxides are produced during combustion of
fossil fuels and arise mainly through the fixation of
atmospheric nitrogen at high temperatures. Thus, nitrogen
oxide emissions depend primarily on the combustion process
rather than on fuel properties. Hence, the nitrogen oxide
emission trends have substantially higher uncertainties
than those for sulfur dioxide. The regional nitrogen
oxide emission trends indicate that in the states both
north and south of the Ohio River, emissions have
increased monotonically since the turn of the century.
The northern states (Regions B. D, and E) show a roughly
linear increase since that time, while the southern
states (Region C) exhibit an exponential increase.
A comparison is made of trends in emissions of sulfur
dioxide obtained in our analysis with those from a recent
comprehensive report. Similarities and differences are
~ . .. . . . . .
OCR for page 91
91
examined. A similar comparison is presented for nitrogen
· . .
Oxide emissions.
ACKNOWLEDGMENTS
The development of the SOX and NOX emission
inventories was supported by the Washington University
School of Engineering and Applied Sciences and by the
National Academy of Sciences. Janja Djukic Husar was
instrumental in the acquisition of the data sets. Her
help is greatly appreciated.
REFERENCES
Beaton, J. D., D. W. Bixby, S. L. Tisdale, and J. S.
Platou. 1974. Fertilizer sulfur, status and potential
U.S. Technical Bulletin No. 21, The Sulfur Institute,
Washington, D.C., and London.
Carrales M., Jr., and R. W. Martin. 1975. Sulfur content
of crude oils. Information Circular 8676. U.S. Bureau
of Mines, Department of Interior, Washington, D.C.
Energy Information Administration. 1977-1982. U.S.
Department of Energy, Washington, D.C. Quarterly
Reports, June 1977 to December 1982.
Energy Information Administration. 1981. Content in coal
shipments, 1978. U.S. Department of Energy,
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Energy Information Administration. 1983. Coal
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Gschwandtner, Ge ~ K. C. Gschwandtner, and K. Eldridge.
.
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Hamilton, P. A., D. H. White, Jr., and T. K. Matson.
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Interior, Washington, D.C.
Husar, R. B., J. M. Holloway, D. E. Patterson, and W. E.
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Lesher, C. E. 1917. Coal in 1917. U. S. Geological
Survey. Part B. Mineral Resources of the United
States. Part II, pp. 1908-1956.
OCR for page 92
92
Thompson, D. R., and H. F. York. 1975. The reserve base
of U.S. coals by sulfur content. 1. The eastern
states. Information Circular 8680, U.S. Bureau of
Mines, Department of the Interior, Washington, D.C.
Tryon, F. G. and H. O. Rogers. 1927. Consumption of
bituminous coal. U.S. Geological Survey, Mineral
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Analysis Work Group 2. 1982. Report No. 2F-M.
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Washington, D.C.
U.S. Bureau of the Census. 1919. Census of Manufacturing,
Washington, D.C.
U.S. Bureau of the Census. 1975. Historical statistics of
the United States, colonial times to 1970. U.S.
Department of the Interior, Washington, D.C., pp.
587-588.
U.S. Bureau of Mines. Minerals Yearbook. U.S. Department
of the Interior, Washington, D.C. Annual Publications,
1933-1980.
U.S. Bureau of Mines. Minerals Yearbook. U.S. Department
of the Interior, Washington, D.C. Annual Publications,
1944-1980.
U.S. Bureau of Mines. Distribution of bituminous coal and
lignite shipments. U.S. Department of the Interior,
Washington, D.C. Quarterly Publications, 1957-1977.
U.S. Bureau of Mines. 1971. Control of sulfur oxides,
emissions, in copper, lead, and zinc smelting (with
list of references). Information Circular 8527, U.S.
Department of the Interior, Washington, D.C.
U.S. Bureau of Statistics. 1917. Statistics of railways
in the United States. Interstate CoIIunerce Commission,
Washington, D.C.
U.S. Environmental Protection Agency. 1977. Compilation
of Air Pollutant Emission Factors. AP-42, 3rd ed .
(NTIS PB-275525), Supplements 1-7 and 8-14.
Springfield, Va.: National Technical Information
Service.
U e Se Environmental Protection Agency. 1978. Mobile source
emission factors. EPA-400/9-78-005 (NTIS
PB295672/A17), Washington, D.C.
U.S. Geological Survey. 1880-1932. Mineral Resources of
the United States. Yearbooks, U.S. Department of the
Interior, Washington, D.C.
Representative terms from entire chapter:
emission factors
