LEONARD GREENBURG and MORRIS B. JACOBS Department of Air Pollution Control, City of New York, New York, N. Y.
Sulfur Dioxide in N e w York City Atmosphere This two-year study shows that highest concentrations of sulfur dioxide occur during temperature inversion periods. In all such instances weather conditions extending far beyond the area are the controlling factor
AIR
pollution is a serious and growing problem in all of the large cities of the Cnited States. T h e City of Ken, York is no exception to this general statement (.7). This paper deals with but one facet of the air pollution problem of N e ~ vYork City--namely. with the pollutant sulfur dioxide. T h e magnitude of possible pollution from this one pollutant can be estimated from the fact that the equivalent of nearly 32,000,000 tons of coal are burned in New York City yearly and that one utility alone burns the equivalent of nearly 7,500,000 tons of coal. This latter figure actually comprises about 5.000~000 tons of bi-
Table 1.
Fuel Consumption (Major Utility) 195-2
Coal, thous. tons Fuel oil
Thous. tons Thous. gals. Natural gas Thous. tons
Thous. cu. ft.
Coal equivalent, thous. tons
tuminous coal. approximately 1,700,000 tons of fuel oil (approximately 300:000,000 gallons) and 900,000 tons of natural gas (24 billion cu. ft.) (Table I ) . T h e sulfur content of bituminous coal ranges from 1 to about 4.57,. the average value being of the order 2.57,. Xearly all residual fuel oil (KO. 6) used in the City of New York contains over 2.57, of sulfur. It is clear then since the molecular weight of sulfur is 32 and the molecular weight of sulfur dioxide is 64 that approximately 5yc of the weight of the bituminous coal and residual fuel oil used in New York City is passed into the air as sulfur dioxide. This means
1.95’3
1954
6,004
5,377
4,935
1,259 225,654
1,653 296,342
1,709 306,429
713 19,118,542
868 23,274,177
901 24,159,752
7,976
7,898
7,545
that from the single source mentioned. approximately 335:000 tons of sulfur dioxide is given off to the air every year. Since this source comprises only 287c of the total fuel burned in S e w York City. it is probable that over 1,500,000 tons of sulfur dioxide is given off to the atmosphere every year: and from this a possible 2~200.000 tons of sulfuric acid may be formed. I t must be stressed that the combustion of fuel for industrial, commercial. and domestic heating purposes. for the production of poiver. and for the preparation of hot water are not the only sources yielding sulfur dioxide as a pollutant in the City of New York. There are over 1:000>000 passenger automobiles. 200,000 trucks, and thousands of buses bvhich consume over a billion gallons of gasoline in a year. There are over 10,000 domestic incinerators, and there are thousands of trash fires in the City of New York. All of these contribute in some measure to the amount of sulfur dioxide in the city atmosphere. I t is necessary to point out also that though the major amount of sulfur dioxide in the Piew York City atmosphere is produced by these sources, some of the pollutant is carried over the city from S e w Jersey by the prevailing westerly \vinds. VOL. 48, NO. 9
SEPTEMBER 1956
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SULFUR DI OX I DE CONCENTRAT1ONS MANHATTAN, NEW YORK CITY, 1954 X
MORNING MAXIMUM AFTERNOON MAXIMUM A AVERAGE
AFTERNOON MlNlMUl MORNING MINIMUM
k
O.*O
J
f
F
M
A
M
J
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A
S
MONTHS OF THE Y E A R
O
N
D
1954
Figure 1
Sampling Prior to 1953 there was no routine day-by-day sampling and analysis of air pollutants in the City of Kew York !Vith the establishment of the new Department of Air Pollution Control and its laboratory in 1953, sampling and analysis were instituted. T h e air was sampled with a n impinger device routinely each day for 1;’2-hour sampling periods in the morning and in the afternoon using the Hatch modification of the Greenburg-Smith impinger tube (8)and with M:ilson automatic impingers (77) every hour for 24-hour cycles. This sampling was carried out a t fixed locarions in Manhattan and in Staten Island a n d a t various points in Queens, Brooklyn, and the Bronx.
amount of‘ sulfur dioxide as an air pollutant:
Results Sulfur Dioxide: P.P.M. _ _ ~ Peroxide 1odine Fuchsin Method Method Method 0.30 0.30 0.27 0 23
0.15 0.15
0.15 0.14 0.11 0.09
0.26 0.23 0.22 0.22 0.14 0.12 0.11 0.11 0.09 0.09
0.25 0.22
0.22 0.22 0.12 0.10 0.09
0.09 0.07
0.0-
n . 0-
0.0’
0.0.5
0.00.06 0 , 05
0.06 0.06 0.06 0.05 0.04
0.15
0.13
0.12
0.05 AV.
Method of Analysis Greenburg and his coworkers (G) compared the peroxide, iodine, and fuchsin methods for the determination of sulfur dioxide in air a n d found that all were equally reliable for determining the
1 51 8
ticularl!- i n the lower concentrations, for the major acidic pollutant is sulfur dioxide. T h e peroxide method is particularl?. useful for field sampling and for sampling with the aid of a Wilson automatic impinger sampler because the absorbing solution is stable, and rhe sulfuric acid formed LYill not decompose on standing. Because of these factors the sample solutions may be titrated relativel!. longer after the sampling period. In the peroxide method (S: 75) the sulfur dioxide is absorbed by a n absorbing solution in which it is oxidized to sulfuric acid. T h e sulfuric acid thus formed is estimated by titration \Fit11 a standard base. Any other acid solublc in the absorbing solution \vi11 also be neutralized by the standard base. Reagents. Hydrogen peroxide absorbing solution 10.03:Y) : Dilute 17 ml. of 3%. hydrogen peroxide solution to 1 liter Lvith distilled Lvater and add 5 drops of mixed indicator solution. Sodium hydroxide solution (0.002.\-) : Prepare this solution by dilution of 1.Y sodium hydroxide solution and standardize against 0.002.V sulfuric acid. T h e sulfuric acid is standardized b) rhe gravimetric barium sulfate method. Mixed indicator (0.1 70): Dissolve 0.6 gram of bromocresol green and 0.4 gram of methyl red in 1 liter of methanol. Procedure. ,4dd 3 drops of mixed indicator solution to 75 ml. of absorbing solution in a Greenburg-Smith impinqer (7: 5’). Neutralize the solution with 0.002.\- sodium hydroxide solution. S o t more than a feiv drops should be necessary for this purpose. Pass air through the absorbing solution a t the rate of 1 cubic foot ‘minute for 30 minutes. Titrate the solution with 0.002h: sodium hydroxide solution.
I n the peroxide merhod the total acidity in the air rather than thar attributable to sulfur dioxide alone is determined, but there is little difference in the results obtained by these methods, par-
INDUSTRIAL AND ENGINEERING CHEMISTRY
T h e results of daily observations (IJ sulfur dioxide concentrations for a period of 2 years show four principal types of variation : 1. Seasonal Variation. There is a seasonal variation in the concentration of sulfur dioxide in which the sulfur dioxide concentration is highest in thc lvinter months of January and December and falls to a minimum in July and August. For 1954 the highest monthly maximum value obtained \vas 0.8 p p . m . in J a n u a q - and December, and the 101~est monthly maximum value \vas 0.29 p.p.m. in .August (FiSure 1). These values are for the morning using the grab-sample technique at approximately 9:30 to 10:OO 4 . 1 i . T h e smoothed curves of Figure 1 show- that this variation holds for monthly maxima: minima: and averages for both morning and afternoon. 2. Daily Variation. There is a dailv variation of sulfur dioxidr (‘on-
A I R POLLUTION centration which generally reaches a maximum during the morning hours in the period 6:00 to 10:00 A . M . T h e concentration then diminishes until about 2:00 P.Y. Subsequently it increases in the late afternoon or early evening and then decreases again to about 2:OO o'clock in the morning. This cycle corresponds roughly \iith that found by Davidson ( 4 ) for smoke shade.
Table 11. Sulfur Dioxide Concentrations and Temperature Inversions SOL P.P..lf. 0.80
0.65 0.59 0.36
Sulfur Dioxide, P.P.M. ?*larch April May ~~
Hour
12-1 A . M . 1-2 2-3 3-4 4-5 5-6 6-7 '-8 8-9 9-10 10-11 11-12 12-1 P.M. 1-2
2--3 3-4 4-5 5-6 6-' 7--8 8-9 9-10 10-11 11-12
0,13 0.15 0.14 0.14 0.17 0.22 0.32 0.34 0.33 0 31 0.25 0.26 0.24 0.24 0.22 0.21 0.22 0.23 0.26 0.27 0.28 0.25 0.19 0.16
0.12 0.09 0.10 0.10 0.12 0.13 0.22 0.28 0.25 0.22 0.21 0.17 0.18 0.17 0.15 0.12 0.15 0.17 0.17 0.19 0.21 0.20 0.16 0.13
0.13 0.13 0.15 0.15 0.15 0.14 0.18 0.22 0.24 0 20 0.18 0.14 0.14 0.10 0.08 0.09 0.09 0.09 0.10 0 11 0 14 0.15 0.15 0.12
\Vhile this daily pattern is generally maintained throughout the year, it is to be understood that on any given day wide variations may occur so that a t times, even a t 2:00 P . M . or a t 2:OO . 4 . ~ . >the maximum of the day may be found. Also in accordance with the seasonal variation, the daily maximums a n d minimums are higher in the \Tinter than in the summer. 3. Temperature Inversion Variation. T h e temperature of the air generally decreases with increase in height--that is? as one goes higher into the air the temperature goes down. This is the classical or "normal" lapse rate. A weather temperature inversion is said to exist when the temperature increases with height. Such weather inversions can start a t ground level or a t relatively low distances from the ground, say 400 to 600 feet, or a t much higher levels of the order 1000 to 3000 feet and even higher. Table I1 gives typical sulfur dioxide concentrations correlated with the lveather condition existing in the 24-hour period in which the analysis \cas made. Inversions which start at ground level and extend to 500 feet and above-
0.43 0.40 0.39 0.31 0.24 0.23 0.22 0.21 0.18 0.17 0.07 0.04 0.01
Iizwsioii Condition' From surface to 2670 ft. with secondary inversion from 4140-4920 ft. From surface t o 500 ft. with secondary inversion from 4000-4920 ft. From surface to 1360 ft. From surface to 630 ft.; isothermal layer from 3300-4500 ft. Isothermal layer from 462-475 ft. From surface to 330 ft. Isothermal layer to 360 ft. Isothermal layer from surface to 100 ft.; inversion from 25004300 ft. 3000-4500 ft. 40004500 ft. 2200-3800 ft. 2330-4100 ft. 1460-2240 ft. 1250-1970 ft. None None None
a From Raob soundings, Mitchell Air Force Base, Hempstead, Long Island.
that is. \yell above even high stack heights--contribute to the higher concentrations of sulfur dioxide. This is probably the result of virtually no air movement or, as we have termed this condition, air stagnation. Often secondary inversions occur at higher levels. Isothermal layers, particularly layers of higher temperature above layers of colder air, have similar effects. T h e sulfur dioxide concentration has ranged from 0.80 to 0.56 p.p.m. under such conditions. Inversions starting a t 460 feet or just above high stack height are the second largest cause of high sulfur dioxide concentrations. Inversions which start a t ground level but extend only slightly above low stack heights (about 300 feet)
may also be included in this categor),. T h e range of sulfur dioxide concentrations are 0.31 to 0.43 p.p.m. Inversions beginning a t a height 01 1200 feet and above cause the least amount of air stagnation, a n d thus have lesser effects on the sulfur dioxidc concentration. T h e range of sulfur dioxide in this instance was found to tic from 0.17 to 0.24 p.p.m. When there is no inversion the dibpersion of gaseous pollutants generally proceeds very rapidly, and the sulfur dioxide concentrations range from 0.01 to 0.07 p.p,m. Therefore, in the New York City area a knowledge of the sulfur dioxide concentration enables one to predict the intensity of many weathrr inversions. Conversely, with a kno\vledge of the type of the temperature inversion present one may predict the probable range of concentration of sulfur dioxide pollution. 4, Geographical Variation. In general the sulfur dioxide concentration falls off Lvith distance from blanhattan. Thus. for instance, our grab results for over 2 years in Staten Island sholi. that borough to have consistently lowcr sulfur dioxide concentrations than hlanhattan. However. in the more densely populated areas of the city there is relatively little variation in sulfur dioxide concentration. Thus grab results in Manhattan and a t approximately thr same time in the Borough of Queens a n d the Borough of Brooklyn (Greenpoint section) show good correlation \vith results obtained in Manhattan. O n two occasions during the current year there \vas a marked geographical variation in sulfur dioxide concentration. Beginning on June 1> 1955. at l : 0 0 P . M . and continuing for 50 hours thc concentration of sulfur dioxide was consistently high (0.4 p,p.m.) at our station in Public School No. 3, Pleasant Plains, Staten Island. A comparison of the results obtained a t the Staten Island station and a t our laboratory i n Nr\i. York is as follo\vs:
Staten Island Average. p p.m. 1 : 00 P v. 6, 1 55 to 1:00 P . M . 6,'3 Si 6 2 55
o
Alaximum, p.p.m. ~ : ~ O P6M / 1 ./ 5 5 t o 1 :00 P . M . 6 3 5.i
0 47 (1:00 to 2:oo 6 '2,'55)
38
0 07
0.39
0.07
(0.45 a t 6:00 6 '2 '55) hlinimum. p.p.m. 1 :00 P . M . 6, 1 55 to 1 :00 P . h i . 6 3, 55
Manhattan LahoratoiL
P
0 2'
(6:00
4
~
6 .2 5 5 )
A.Y
0 32 ( 9 . 0 0 M ~ 6 2 55)
VOL. 48, NO. 9
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04 i ? 00 4 00 4 hf dnd 3 0 0 - 5 . 0 0 ~6 ~2 5 i )
SEPTEMBER 1956
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These data show a consistently high sulfur dioxide concentration for a period of 50 hours ranging from 0.32 to 0 47 p.p.m. in Staten Island as contrasted with 0.04 to 0.27 p.p.m. in Manhattan. As noted, sampling has shown Manhattan to have consistently higher sulfur dioxide concentrations than Staten Island. Katz (70) claims that a fumigation concentration of 0.4 p.p.m. can be damaging to vegetation if sufficiently protracted. Thomas and his coworkers (76) also have noted the effects of sulfur dioxide on vegetation. T h e results obtained with the smoke shade instruments did not show any unusual variation during this period T h e results in Manhattan \vere uniformly higher than those in Staten Island :
calculated as sulfur dioxide TVe have shown that the major portion of such acidity is sulfur dioxide ( 6 ) . Severtheless, it must be borne in mind that other sulfur bearing components ( 9 ) and other acidic substances are present as air pollutants. I n comparison tvith the amount of data collected for sootfall. smoke shade, and, somewhat more recently, suspended particulate matter. there has been relatively little data collected on the concentration of sulfur dioxide in the air of cities in the United States. Slajor studies have been made in Los .4ngeles, Cleveland ( 7 I). the Detroit-TZ'indsor .4rea ( 7 7 ) and Cincinnati ( 2 ) . T h e analyses of the Department of .4ir Pollution Control of the City of Ne\% York. reported here, constitute one of
Staten Island
Manhattan Laboratory
Average, COH units 1 2 Noon 6 1 55 to 12 Noon 6 3 55 6 2 55
0.7
1.4
0.8
1 5
Maximum, C O H units 12 S o o n 6 1 /55 to 12 Noon 6 3 55
1 6 ( 6 : 0 0 - 8 : 0 0 ~and ~ 2 : 00-4: 00 P . h i . 6 2 55)
2 5 ( 6 . 0 0 to 10:OO 6 3 55)
IMinimum, COH units 12 Noon 6 1 55 to 12 S o o n 6 3 55
0 1 (10:00-12:00 Noon
0 5 (2:OO-4:OO ~ and 4.00-6:00 6 2 55)
6 3 55)
A second abnormal period existed from July 14 to July 21 (Table 111). In this instance, too, the minimums in Staten Island were as high as the maximums in Manhattan and the average was two to three times as high in Staten Island as in hfanhattan. T h e weather conditions for both these instances were such that it is highly likely that the pollution was blown from the industrial area of New Jersey which lies southwest, west, northwest: a n d north of Staten Island over this borough. Discussion T h e results detailed here, as mentioned, represent total acidity in the air
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A M
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the few systematic surveys of sulfur dioxide concentration over a 2-year period in a large city in the United States. Typical results for various studies in the United States are as follows (72); other data have been published (7: 3 ) :
City
Av., p.p.m.
Max.. p.p.m.
Altoona, Pa. Atlanta. Ga. Baltimore, Md. Birmingham, Ala. Charlotte? N. C. Chattanooga, Tenn. Chicago. Ill.
0.008 0 012 0 021 0 017 0.015 0.011 0 067
0.024 0.069 0.366 0,087 0.050 0.044 1.141
Table 111.
Cincinnati, Ohio Cleveland, Ohio Ft. Wayne. Ind. Harrisburg. Pa. Indianapolis. Ind Johnstown, Pa. Louisville, Ken. Kashville, Tenn. Richmond, \-a. Springfield. 111. Toledo. Ohio TVheeling. TI'. \.a. Youngstoun. Ohio
0 107 0 281
0 021
0 064 0 028 0 011 0 0 0 0 0 0 0
023 014 022 028 009
021 023
00 ' 0 049
0 309 0 037 0 093 0 038 0 119 0 119 0 025 0 169 0 072 0 320 0 162
1Vhile the amount of coal being used by the public utilities in the City of New York is steadily decreasing, thr amount of fuel oil, particularly residual or S o . 6 fuel oil? used is increasing. Consequently, there is little prospect of any material decrease in the amount of sulfur dioxide passed into thr air \vithin the immediate future unless the amount of sulfur in residual fuel oil is markedly reduced. I t may \vel1 be that as other fuels. such as natural gas and "atomic" fuels, are used instead of coal and rrsidual fuel oil. there \vi11 be a reduction in the sulfur dioxide concentration i n the S e w York City atmosphere. Such changes in fuel may. hoivever, introduce other, possibly more harmful, pollutants into the atmosphere. Seasonal Variation. T h e fact that the sulfur dioxide concentration varies Lvith the season of the year has been noted in the past. For instance. Karz 1 7 7 ) stated in a report concerning [he Detroit-PVindsor International Program. "the pollution load. as indicated by variations in intensity and frequency of sulfur dioxide fumigations. shows marked seasonal as \
