Ilution in the Area SPOKANE COUNTY, WASHINGTON D O N l L D F. ADA>IS, DELBERT J. MAYHEW, RICHARD AI. GNAGY, EUGENE P. RICHEY, ROBERT K. KOPPE, AND IVilN W. ALLEN Division of Zndustriul Research, Wushington State Institute of Technology, The State College of Wushington, Pullman, Wash.
T h e ponderosa pine trees in the industrialized area north
of Spokane, Wash., have exhibited a characteristic reddening of the needles since 1943, lcnown locally as “ponderosa pine blight.” The blighted area now embraces approximately 50 square miles, and the trees within a 3-square mile area near the center are dead. As a portion of a coinprehensive investigation, the concentrations of gaseous fluorine and sulfur compounds in the air during the growing season of 1950 have been determined through operation of tw-elve air-sampling stations and a mobile air-
URVEYS of the “pine blight“ area of Spokane County, Washington, indicate that it lies principally in a valley which is about 3.5 miles wide and extends north and south for 10 to 12 miles along the valley. Damaged trees are also found on the bluffs on the east and west sides of the valley. The area includes the community of Mead and extends southward into the northern portion of the city of Spokane. The observed visible extent of the area of damaged ponderosa pine is outlined in Figure 1. Figure 2 indicates the topography of the area. Three major industries are located on the valley floor north of the Spokane city limits. These include a small oil refinery: which has been located there for many years; a smelter built during the early part of World War I1 to produce magnesium and ferroalloys; and an alumina reduction plant built during this same period. The two latter operations viere closed for a short time following the war and then reopened. Early observations of the blighted condition of the pine are fragmentary and it was not until 1945 that Harold Abbitt, Spolrane park superintendent, made an accurate appraisal of the situation. The ponderosa pine in Franklin Park on the north side of the city as well as the pine further north were slowly succumbing t o a needle blight. I t was not until 1949, however, that citizens organized the Inland Empire Pine Damage Committee and concluded an agreement with the State College of Washington t o investigate the causes of the ponderosa pine blight. PLAN OF INVESTIGATION
The investigation had two main objectives: to obtain complete information concerning the various factors that might be directly or indirectly responsible for the blight, and to reproduce the observed injury under experimentally controlled conditions once the casual factor or factors had been established. To accomplish these objectives, four groups of factors were investigated: (1) atmospheric pollution, including air and vegetation analysis, (2) fungus and bacterial diseases, (3) insect pests, and (4)soils and climate. An investigative team including chemists and plant pathologists of the State College of Washington and entomologists and foresters of the United States Department of Agriculture was coordinated by George W. Fischer, chairman of the Division of Plant Pathology of the Agricultural Experiment Stations. The results of these investigations, including con-
1356
analysis laboratory. Analj sis of rain-water samples obtained during each rainy period throughout October and November 1950 at 82 locations established the points of origin of the contaminants and the extent of their dispersion. Meteorological and topographical conditions in the ponderosa pine blight area, w-hichcontrol the dispersion of pollutants and explain the damage and pollutant concentration patterns, are discussed. Concentrations of gaseous fluorine compounds in the atmosphere of the area w-ill serve as a guide in controlled fumigation of ponderosa pine.
trolled fumigation experiments, will be reported by the vaiious investigators. The Air Pollution Section of the Division of Industrial Research set up a program t o determine the concentrations of gaseous sulfur and fluorine compounds within the damaged area. These gases have been reported to cause vegetation damage in other localitiee. The literature on this subject has been reviewed by Thomae and Hill ( l a ) , Kat2 ( 4 ) ,RIacIntire et al. ( 7 ) , Miller, Johnson, and Allmendinger ( 8 , 9 ) ,and others. Three of the many lines of inquiry followed during the 1950 growing season are reported: air sampling through operation of twelve stationary sampling units and a mobile air-analysis laboratory, collection and analysis of rain water from 82 locations within the damaged area during the fall rainy season, and analysis of the micrometeorology of the blighted area to enable correlation and interpretation of the data concerning the dispersion of the industrial pollutants. P I N E BLIGHT CONDITION
The pine blight condition is characterized by a reddening of the needles, progressing from the tip downward to the base (Figure 3). In severe cases the needles are shortened to one fourth of their normal length, and the needle density on the twigs suffers a marked decrease (Figure 4). The trees severely affected retain their needles only for 1 to 2 years rather than the usual 4 to 6 gears. Many of the ponderosa pine within a 50-square-mile area show the characteristic reddening attributed to the blight, and a large percentage of these trees within a 3-square-mile central area have been killed (Figure I). Analyses of damaged pine needle samples show considerably higher fluoride content than do those collected 10 or more miles from the center of damage (11). MICROMETEOROLOGY OF P I N E B L I G H T AREA
In a consideration of the ponderosa pine blight problem, it ia necessary to understand the way in which meteorological and topographical factors combine to influence the dispersion of the pollutants present within the damaged area. As the pollutants are discharged into the atmosphere, the wind currents transport and disperse them in a very complex manner. The major dispersing factors, as they were found to apply to the general area under consideration, have been investigated.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 6
Air Pollution Inversion Layer. The temperature above the ground layer usually decreases with an increase in elevation; however, within the ground layer, the temperature frequently will increase with elevation. This condition is known as an “inversion.” The warm upper layer acts as a lid, holding gases, dusts, or fumes within this ground layer, for the pollutants do not have sufficient lift or buoyancy t o break through the inversion layer. Under inversion conditions, therefore, the concentrations of atmospheric pollutants tend to increase, since under these conditions, wind speeds are also very light and vertical mixing does not take place. The average number of days per month when inversions are present in the Spokane area, based on Spokane Weather Bureau data covering 1944-49, are shown in Figure 5. It is extremely fortunate that the average number of surface inversions decreases to a minimum during the d o n t h of June, because it is during this period that thenew, rapidly developing needles exhibit the greatest period of fluoride uptake of their life cycle (11). Figure 1. Approximate Areas of Complete Kill and Visible Pine Needle Injury Attributed to Ponderosa Pine Blight The months of greatest inversion frequency-fall, winter, Area within heavy black line shows approximate maximal limit of pine damage, 1950. Area within broken black line, complete kill and early spring-coincide with the ueriod of least uhvsio. “ logical activiCy of the trees, This fortuitous situation results wind direction frequency roses for each month during the growin the least incidence of inversion-type fumigations during ing season-April through October 1950. A typical month’s wind rose is shown in Figure 6. Data on monthly wind direction the late spring and early summer, the period of maximum plant activity, and the greatest incidence of inversion-type fumigations frequency from the Spokane Weather Bureau at Geiger Field and from a recorder located near the center of the damage area during the period of plant dormancy. Unpublished.analyses of more than 6000 pine needle samples taken at monthly intervals are plotted on separate wind roses in the same figure to illusover a‘period of more than a year show no further uptake of attrate this influence of topography. The wind roses for each of the two locations show the number of hours of wind of a specified mospheric fluorides from October through April. The air analyses reported in this paper were obtained during the 1950 growdirection as percentages of the total number of hours recorded. ing season, during which a progressive increase in visible damage The percentage wind direction frequencies from each of the two recorder locations for the 7 months’ growing period have been was accompanied by a month to month increase in the fluoride content of the needles (11). averaged and plotted in Figure 7 , t o show the effect of topography of the damage area and the major directions of both low and Topography and Wind. The motion of the air from the ground level up to a height of several hundred feet is strongly affected high velocity winds. The total effect of the hills surrounding the basin is to direct more of the winds from the plateau region by the topography. The area immediately north of the city of Spokane lies in a shallow valley roughly of horseshoe shape, with southwest of the damaged area into the northern and southern the open end extending toward the south across the northern half sectors. The primary wind direction for all wind velocities a t Geiger Field is south southwest and the secondary direction is of the city. Five Mile Hill forms the western boundary, the foothills of Mt. Spokane the northern, and the hills near St. east northeast. In the area of damage the primary direction is south to south Bouthwest and the secondary direction is north Michael the eastern boundary. Narrow valleys open toward the northeast to north. The topography of the area of damage has northwest and northeast corners. Although the valley floor is been responsible for a 12.5’ shift toward the south in primary generally flat, it is broken by small ridges and hills (Figure 2). All these irregularities create eddies and local variation in wind wind direction and a 25 shift toward the north in secondary wind direction and velocity near the ground, although the direction direction. and speed of the winds aloft are steady. The wind directiop pattern in the valley determines the course The influence of the topography of the blighted area upon the which the stack effluents will follow, but the velocity is of equal macrometeorology of Spokane County was shown by plotting importance in the analysis of the atmospheric pollution of the June 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Air Pollution
Figure 2.
Topographical Map of Spokane and Vicinity
area. Higher wind speeds tend to break up any surface inversion, t.o mix the air in the ground layer, and to disperFe any contaminants. At the higher velocities a greater volunie of air moves past a given location, so that the contaminants are more rapidly diluted. Average percentage direction frequencies for winds of velocity less than 8 miles per hour as recorded a t Geiger Field and near the center of damage also have been plotted in Figure 7 . Wind speeds of greater than 8 miles per hour have greater diluting and mixing action and thus produce lower concentrations of gases a t distances over a mile from the center of damage than do the wind3 of lower speed. For wind speeds of less than 8 miles per hour, tlhe pattern of petcentage wind direction frequency is reversed. The primary low velocity winds at Geiger Field are east northeast t o northeast and the secondary winds are cast southeast. I n the area of damage the primary direction of the low velocity winds is northeast, north northeast, north, and north northwest and the secondarv direction is south t o south southwest. Again the topography exerts its directional effect upon the incoming winds. This analysis of the effect of wind direction, frequency, and speed upon the damage pattern lends credence to the observed area of needle burn. The general equality of the
1358
percentage frequencies of low velocity winds over a 37.5' arc from north northwest to northeast and the widening of the valley south of the damage center are largely responsible for thc broadening of the damage pattern in the southern sector; while the south to south sout,hwest character of the secondary low velocity winds as well as the narrow valley extending northward from the center of damage is largely responsible for the narrow t'apering character of the damage outline in the northern sector. The nocturnal, low velocity air flow from the slopes of M t . Spokane is partially responsible for the high frequency of low velocity northerly winds in the area. Colder air from the slope to the northeast, flowing under the warmer air in the valley, sets up inversions and moves the pollutanls southward towwd the city. The dispersion of contaminants within the area depends upon an intricate relation among the variables of wind speed and direction, inversion and its intensity, and topography. ANALYSIS O F THE 41K
Analyses of the air were made t o establish the average conccntrations of gaseous sulfur and fluorine compounds 111 the at-
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Vol. 44, No. 6
-Air
Pollution-
procedure (1). Sulfur-containing gases were absorbed in a scrubber containing 200 ml. of 0.01 N sodium hydroxide. The concentration of collected and oxidized sulfur compounds was determined gravimetrically (IO).
Figure 3. Ponderosa Pine Needles Showing Characteristic Burned Effect of Ponderosa Pine Blight
mosphere of the blighted area a t all times of day, a t typical damage classification locations, and under varying meteorological conditions throughout the growing season. T o establish the dispersion of the atmospheric pollutants within the area, twelve stationary air-sampling units were designed and located through the damaged area during the first week in April 1950. These units permitted sampling of the air for gaseous fluorine and sulfur compounds at twelve sites simultaneously.
A typical station consisted of a surplus Navy peacoat locker equipped with a 1.5 hp. gasoline motor to power the suction pump, a 5-gallon gasoline storage tank, two dry-test flowmeters, two sets of fritted-glass absorption towers, a dust filter, and an inlet tube extending 15 feet above ground level. The apparatus is shown diagrammatically in Figure 8. A jeep truck was used to service t,he air-sampling stations every 8 hours. The truck contained a 50-gallon gasoline storage tank, a 150-gallon t,inned distilled water tank, reagent storage bottles, drawers for 300 po1yet)hyIene and glass sample storage bottles, and a complete store of spare parts and tools (Figure 9). From April through September 1950, the twelve air-sampling stations were operated continuously on alternate weeks. The absorption samp!es t,hat were collected during one week were returned to the laboratory for analysis the following week. This schedule of operation permitted the samples to be obtained under a wide variety of meteorological conditions throughout the growing season. The operators, working in three 8-hour shifts, visited each of the stations once during each shift, to service the motors and pumps, to make minor qdjustments and repairs to the equipment, to add liquid to the absorption towers, to record flowmeter readings, to obtain micrometeorological data with equipment carried in the truck, and to transfer the absorption solutions to samplestorage bottles a t the conclusion of each absorption run. Samples obtained from nine of the stations represented 24-hour absorption periods, while 8-hour absorption samples were taken from the three stations located near the center of the damage area.
Results. GASEOUSSULFURCOMPOUNDS.Attempts to establish gaseous sulfur compound concentration on an 8- or 24hour basis were discontinued in midsummer for three reasons: It, was apparent from the analytical results that the average concentrations of gaseous eulfur compounds at the sampling stations were on the order of 0.1 p.p.m. or less (Table I ) ; the Titrilog was employed to give instant,aneous and continuous sulfur dioxide readings, and thorough examination of sulfur dioxide-sensitive plants throughout the entire Spokane area failed to disclose visible traces of typical sulfur dioxide damage, The Consolidated Engineering Titrilog, a chemical-electronic instrument for the continuous recording of trace quantities of oxidizable sulfur compounds in the atmosphere, was employed in the mobile air-analysis truck during the months of September and October (Figure 13). The Titrilog operates on the principle of continuously titrating, to a potentiometric end point, compounds that exert a reducing action on electrolytically generated bromine in acid solution. With this instrument a continuous, instantaneous, quantitative recording of oxidizable gaseous sulfur compounds was obtained in 30 or more separate locations during an 8-hour shift, using 10-minute sampling periods.
Figure 4.
Severe Case of Ponderosa Pine Blight
Decreased needle density on s a m e group of tree8 during 12 m o n t h s , 1 m i l e from center of damage area, July 1949, July 1950
Most of the air sampling was conducted a t night or in the early morning hours to obtain samples during periods of maximum inversion intensity. Throughout these 2 months, concentrations of oxidizable gaseous sulfur compounds in the atmosphere Routine Analytical Methods. Fluorine compounds in the sampled did not exceed 0.10 p.p,m. with the exception of a brief air were collec,ted by passing air, at the rate of 1 cubic foot per 15-minute fumigation. During this one period the concentraminute, through two fritted-glass absorption towers in seriee. tion was 0.25 t o 0.30 p.p.m. a t the top of a small hill near the The towers contained 200 ml. of 0.01 N sodium hydroxide. The damage center (air-sampling location 11, Figure 2). Samples fluorine content was determined by colorimetric thorium alizarin titration of the Willard-Winter distillate according to the A.O.A.C. taken immediately preceding and following this fumigation, both a t the bottom and a t the top of the hillj.showed concentrations of less than 0.10 p.p.m. Concentrations of sulfur compounds up to 0.40 p.p.m. have been demonstrated by Thomas (lb), Kat2 ( 4 ) , TABLE I. ~ L V E R A G ES U L F U R DIOXIDECONCENTRATIONS AT k R and others t o be without detrimental influence on plant life. S.4hIPLINCr STATIONS GABEOUS FLUORINE COMPOUNDS. The concentrations of gaseStation No. 1 2 3 4 5 6 No. of observations 31 97 33 34 37 38 ous fluorine compounds represent average values for either 8- or Av. 802, p.p.m. 0.005 0 . 0 1 0 0.005 0.005 0.005 0 . 0 0 5 24-hour periods and do not indicate possible short-time fluctuaHighest S O ~ o b s e r v e dP, . P . ~ . 0 . 0 1 9 0 . 0 4 0 0 . 0 3 1 0 . 0 2 0 0 . 0 3 9 0 . 0 1 1 tions. The graphs, therefore, show the daily averzge stepwise Station No. 7 8 9 10 11 12 No. of observations 22 42 41 40 24 41 variations. The concentrations of fluorine reported represent Av. SO?, p.p.m. 0.007 0 . 0 0 5 0.013 0.010 0.018 0.006 HighestSOrobserved, p.p.in. 0.082 0 . 0 1 7 0.079 0.096 0.147 0.034 only gaseous, water-soluble fluorine-containing compounds, since the absorption towers were preceded by dust filters to remove par-
Figures 10 to 12 show typical air-sampling stations and the condition of the trees at, these locations.
June 1952
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
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Air Pollution-, ticulate matter. This separation was justified on the basis that vegetation damage would result from contact with water-soluble gases rather than with relatively stable and insoluble particulate material (Y).
E
NUMBER
O F INVERSONS AT SURFACE OR W I T H TOPS THAN 2000 F E E T ABOVE SURFACE
LESS
MON’HLY
DISTRIBUTION OF
Figure 5.
pattern for each individual sample t o determine the wind direction that existed for greater than 50% of the sampling time. The wind pattern that existed immediately preceding each sampling peTiod was not considered. The effect of this type of treatment of data is reflected in the east and west wind considerations, for these winds were of short duration and samples obtained under these conditions were strongly influenced by the preceding wind pattern.
A typical example of the effect of the wind condition which preceded the reported sampling period is that of station 9 under conditions of westerly wind. From August 11 through several hours of the sampling period on August 15, t,he wind was blowing from the south. The data in Figure 15 indicate that a concentration of 3 parts per billion of fluorine was obtained a t stat,ion 9 during a period of west wind. I n reality, the concentration reflects the result of the previous southerly wind. This effect was minimized a t stations 2, 7 , and 11 by using an 8-hour sampling period. The influence of the 4 days of south wind preceding the short period of west wind must be considered in the evaluation of theJe data. Three samples from each station were obtained under cast wind conditions and show a more complete picture of atmospheric concentrations of pollutants than in the case of west wind conditions (Figure 15). The highest concentrations of pollutants during east wind flow were found at stations 10, 8, i, 1, 2, 11, 12, and 9. All the stations except No. 7 were located to the west of the north-south axis of the area of damage. Stations 3, 4, 5 , and 6, with the lowest concentrations of pollutants, were located farther upwind from the center of damage than S o . 7 .
--
INVERSIONS IN SPOKANE AREA
Inversions
A-
15r
GEICER - A L L SOEELIS CENTER OF 04UAGi A L L SPEEDS
-
#
The result8 of all the analyses for fluorine (reported as parts per billion F-) and the more significant meteorological data for the air-sampling period, May through September 1950, have been compiled in Figure 16. The relationships between wind direction and wind speed and concentration of airborne gaseous fluorine compounds have been established through analysis of the data shown in this figure. CONTAMINANTS I N RELATION TO W I N D DIRECTIOX Figure 14 shows the average concentration of gaseous fluorine compounds in relation t o wind direction and air-sampling stations. Figures at the top of each column indicate the total number of observations. As samples from nine of the stations represent 24-hour average concentrations, and wind directions sometimes changed during the sampling period, it was necessary to considei the wind
I! P
51
’‘
N
NNE N E
ENE
E
ESE S E SSE S SSW SW WSW W!ND DIRECTION
-a-
W WNW “NNNW
GEIGER -.-CENTER
Figure 7.
- BELCW
N
NNE
8 MPH OF DAMAGE BELOW 8 M P H
-
Average Wind Direction Frequency
4 t Geiger Field and center of p i n e damage, 4pril through October 1950 AWUST I950
Figure 15 shows a regrouping of the data of Figure 14 to show the effect of wind direct,ion on the average concentration of gaseous fluorine compounds a t each air-sampling station.
S
GEIGER FIELD WINDS BELOW 8 M P H
EARS POINT T O W A R D D I R E C T I O N FROM WHICH
Figure 6.
1360
WIND
IS
COMING
Percentage Frequency of Wind Directions
The direction and the distance in milev from the center of damage t o the station location are indicated below each station number. The number at the top of each column indicates the maximum concentration of fluorine in parts per billion at each station for yinds from each of the four quadrants. Station 11, 0.5 mile south of the center of damage, had very similar average concentrations during both south and north winds, but with concentrations only one half t o one sixth as high during east and west winds. The highest concentration, 73.4 parts per billion, was obtained toward the end of a rainy period when the wind speed had decreased to less than 7 miles per hour. Station 2, 1.5 miles south of the damage center, showed almost, three times as high an average concentration during north winds as when the winds were from other directions. The highest concentration, 42.1 p.p.b., was obtained during a variable north
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
Vol. 44, No. 6
Air Pollution AIR INTAKE
I
METER
I
1 SULFUR
FLUORINE
COLUMN
COLUMNS
I-
1
7
OUTLET
ENOINE
Figure 8.
VACUUM PUMP
Schematic Diagram of Air-Sampling Apparatus
wind condition with wind velocities below 2 miles per hour. Station 4, 2.25 miles southeast of the damage center on the bluff at St. Michael's, showed very little variation in concentration, The highest concentration, 3.5 p,p.b., was recorded during northerly wind flow. Station 12, 2.5 miles west southwest of the damage center, on Five Mile Bluff, showed its highest average concentration during conditions of east winds. The highest concentration, 10 p.p.b., was observed with a northeast wind. Station 1 3.5 miles south southwest of the damage center, at Franklin hark, had very little variation in average concentration. Maximum concentrations in the order of 4 p.p.b. were observed with both north and south winds. Station 3, 7 miles southeast of the damage center, overlooking Irvin and Millwood, had next to the
Figure 10.
Air-Sampling Station
3.5 miles south southwest
lowest average concentrations and the lowest maximum concentrations of all of the air-sampling stations. A maximum of 4 p.p.b. was obtained during a period of south wind. Station 7, 1 mile north northeast, had the highest average concentrations of all the air-sampling stations, 10.2 p.p.b., with a south wind. It also had the highest concentration obtained during the entire sampling program, 351 p.p.b., during a period of south wind. Station 10, 1.5 miles west at Whitworth College, had an average concentration of 6.3 p.p.b. with east winds. The highest Concentration determined a t this location wm 17.3 p.p.b. with an east wind. Station 5, 1.75 miles east northeast near Mead, had the highest average concentration under conditions of south wind, and a maximum concentration of 19.9 p.p.b. during a south southwest wind. Station 8, 2.75 miles north northwest at the Kiwanis Camp in the Little Spokane River valley, had exceptionally high average concentrations, considering its distance from the center of damage. Maximum concentrations of 15 t o 16 p.p.b. were observed with both north and south winds. This may be partially explained on the basis of topography and the accompanying low wind velocities at the time these samples were obtained and on presence of a ground inversion. This inversion remained in the Spokane area for 4 days, and was intensified in this locality by the proximity of the Little Spokane River.
OF FLUORINE CONTAMINANTS IN TABLE 11. DISTRIBUTION RELATION TO WINDSPEED
F-Canon.,
P.P.B. 0-5 5-10 10-20 20-50 50
+
Total
Figure 9.
June 1952
Interior of Jeep Truck Used in Servicing AirSampling Stations
Total No. Samples
1452 38 19 8 3 1520
Wind 0-3 442 18 6 5 1 472
Speed, Miles per Hour 4-7 8-12 124561 312 137 9 7 4 6 6 1 1 0 2 1 1 0 578 326 144
Station 9, located 3.5 miles north northwest on a high point 0.5 mile north of station 8, had its highest average concentrations either during southerly winds or in a period of west wind immediately preceded by southerly winds. A maximum concentration of 42.5 p.p.b. was observed during a period of southerly wind. Station 6, 3.25 mi!es northeast on hjgh ground, had,the lowest average concentratlon of the twelve alr-sampling locations and a maximum of 2.5 p.p.b. was observed under north wind conditions.
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A
i
r PollutionOF FLUORINE CONTAMINAXTS IN RELATION TO WIKDSPEED ASD CONCENTR.~TION TABLE 111. DISTRIBUTION
Distance from Damage staCenter tion DirecSo. tion Miles 1
2 3 4 5
5
A9
10 11 12
Total
SSU' s
SE SE
EKE NE NNE NNW NNW
w s wsw
3.5 1.5 7 2.25 1.75 3.25 1 2 75 3.5 1.5 0 5
2.5
~
_
~
0-3
_
_
~
0-5 5-10 10-20 20-50 50'.
32 36 36 38 38 40 33 32 39 37 33
1
.
3 1
i
..
.
3
..
3 6
38
-LI.
432
18
..
1
.. ..
1
..
..
3
.. .. ..
-61
.. .. .. .. 1 .. 1
0-5 42 50 48
49 49 48 44 42 48 45 48 48
5-10
..
2 2
.. .. .. ..1 1 1 1 1
I .
.1. .. 3
.. .. 1
.. .. ..
.. .. .. ..
... 1.
-0 - -
I
561
Wind Speed, Miles per Hour ~_ _ _ _ 4-7 8-12 Fluoride_________ Concentration, parts per _ billion _ _ _ _ _ ~ 10-20 20-50 50f 0-5 5-10 10-20 20-50 50+ 0-5 5-10
1 6
,.
C o N ~ a a r ~ s IS ~ xRJGIATIOS ~s TO ~ ' I S U SPEED. The distribution of concentrations of fluorine compounds lor wind speeds of 0 t o 3, 4 to 7 , s to 12, and over 12 miles per hour is shown in Table 11. The tabulation indicates the number of samples within arbitrary concent,ration ranges and shows the influence of wind bpeed upon the concentration of contaminants in the atmosphere. In general, there is a trend toward higher concentrations in the wind speed range of 0 to 3 miles per hour. In each of the concentration ranges above 5 p.p.b, of fluorine, the greatest number of samples were obt.ained a t wind speeds of 0 t o 3 miles per hour. A total of 30 samples with concentrations over 5 p.p.b. were obtained a t wind speeds of 3 miles per hour or less, 1'7 samples at wind speeds of 4 to 7 miles per hour, 14 samples a t wind speeds of 8 to 12 miles per hour, and 7 samples a t wind speeds greater than 12 miles per hour. Only 7 of the 144 samples obtained during wind speeds exceeding 12 miles per hour showed
1
26 26
.. .. .. ..
.. ..
..1 -1
-
..
.. ..
..
..
.. ..
'1
..
..
4
28
28 27 26 24 23 25 25 27 27 312
..
1
1
..
..
1
.. ..
. I
2
..
,. 7
2 1
-3
.. ..
.. .. .. .. ..
I
0
12 10 13 12 10 13
10 10 11 13 10 13
m
_12
10-20
+ 20-50
SO+
.. .. .. ..
.. ..
.. .. ..
..
__
0
concentrations above 5 p.p.b. of fluoriue. S o concentrations over 50 p.p.b. of fluorine were obtained a t wind speede above 12 miles per hour. CONT4bIIX'BNTS IX REL.4TIOPI' T O DISTASCL FROV CEXTER O F DAM~GE The . highest concentration of fluorine-containing gas, 351 p.p.b., was obtained a t station 7 , which is on a small knoll less than 1 mile north of the center of damage. The next highest concentration, 73 p.p.b., was found at station 11, approxiinately 0.5 mile south of the center of damage. The concentration of fluorine contaminants at each of the twelve air-sampling stations in relation t o the wind speed ranges is shown in Table I11 Of the eleven concentrations reported in the range of 20 p.p.b. of fluorine or greater, all but two were found within 1.5 miles from the center of damage. Of the 30 recorded concentrations above 10 p.p.b. of fluorine, only two were obtained a t a distance of greater than 2.75 miles from the centei of damage. ANALYSIS OF RAIN WATER
Nost of the particularly harmful chemical bubstances found in the atmosphere which result from domestic and industrial operations are highly soluble in water-e g., the oxides of sulfur and fluorine compounds ( 3 ) . The hygroscopic nature of many of these oxides (acid anhydrides) is largely responsible for the density, persistence, and corrosive nature of smog. In a smog the pollutants remain suspended in the air and the evaporation
Figure 11. Air-Sampling Station 1 mile n o r t h northeast
Figure 12.
Air-Sampling Station
2.5 miles west s o u t h w e s t
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Figure 13.
Interior of Mobile Air-Analysis Laboratory W i t h electrostntir precipitator
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 6
Air Pollution r
damage were contaminated by leaves, as a leaching of some of the fluorine and sulfur in the plant 9 tissue undoubtedly took place. The samples were first made up to 200 ml. S The fluorine concentration was then determined 7 on a 10-nil. aliquot of the rain sample, by coloriu.6 U metric titration of the Willard-Winter distillate * z 5 according to the A.O.A.C. procedure (1). The 4 total sulfur content of the remainder of the rainwater sample was determined gravimetrically as 3 barium sulfate (IO). 2 The sulfur and fluorine concentrations are I reported in arbitrary units of milligrams of 0 I1 2 4 I2 I 3 7 IO 5 s 6 9 / I 2 4 I2 I 3 7 , ; 0 5 8 6 9 substance per collection bottle for each rainfall. SOUTHERLY WIND E A S T E R L Y WIND These units allow a comparison of results 4r 4t between sampling locations. Further calculau 3 tions are required t o establish pounds of sulfur a or fluorine returned to the soil per acre. 2 2 I Results. The results of the rain-water anal0 yses have been plotted by two different I 1 2 4 12 I 3 7 10 5 0 6 9 l l 2 4 1 2 1 3 7 1 0 5 8 6 9 methods. Figures 17 and 18 show the average NORTHERLY WIND WESTERLY WIND dispersion of the pollutants in the sampled Figure 14. Average Concentration of Gaseous Fluorine Compounds area for the months of October and November as a Function of Wind Direction and Station 1950. The concentrations found a t each sampling .~ location for each rainy period were ayerof the fog leaves them in the air; when rain occurs such subaged over the 2-month period. This treatment of the data stances are permanently and effectively removed from the atis justified because the rain bearing winds during October and mosphere. Heavy precipitation is always an extremely effecNovember were from the southwest. tive cleansing agent (18). In effect, the rain acts as a concentratThe east-west and north-south cross-sectional concentration ing agent and was found to be particularly effective for the expatterns, obtained by averaging the concentrations found in each tremely low concentrations which could not be detected by the I-mile increment along two 2-mile-wide strips passing through the gas absorption methods described above. Consequently, the center of damage, are plotted along the edge of the average disdispersion of pollutants in the ambient air of the ponderosa pine persion pattern. The cross-sectional dispersion pattern illusblight area was investigated by an examination of rain-water trates in a striking manner the way in which the fluorine concensamples collected within the area. trations drop t o a minimum on the outer edge of the area sampled. The long-range weather forecast for the area predicted above At the same time many of the highest sulfur concentrations were normal rainfall for the months of October and November and found along the southern edge of the area and bore no relation82 rain-collection locations were established throughout the ship to the location of the three major industries near the center Spokane area, extending a t 6ome points beyond the area of visible of damage. damage. It was anticipated that points on the periphery of the area would show negligible quantities of certain contaminants in the collected rain water Apparatus and Collection of Samples. The rainfall collector used in this study was a 22-ounce ball freezer jar, 3 inches in inside diameter at the 4r top and 6.5 inches high. The cross-sectional collection area was 7.08 square inches. This a bottle was placed in a wooden holder, which was 3 5 '0 3 4 attached a t one end of an 8-foot aluminum pole. The whole assembly was then secured to an STATION I1 STATION 2 STATION 4 STATION12 STATION I existing fence post, small tree, or other support s I/2 s I-IE SE 2-1/4 wsw 2-112 SSW 3112 SE 7 found a t the sampling site. T o ensure complete retention of the acidic pollutants, 10 ml. of 0.1 Ar sodium hydroxide were added to each collector before it was placed on the support. The sample jars were collected as soon as possible following each rainy period, to prevent secondary contamination. Sampling locations were selected so as to minimize local contamination or shielding by buildings or large trees. The rainfall collectors were located at a distance from a shielding object equal to twice the height of that shielding object. Routine Analysis. In the laboratory all leaves, dust, etc., were removed by filtration, so as to obtain a sample representative of the gaseous Pollutants brought down by the rain. A special Figure 15. Average Concentration of Gaseous Fluorine Compounds as note was made when samples within the area of a Function of Station and Wind Directions I'
I
I
0
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Pollution
Figure 17'. Rainfall Studies in Portion o f Spolrane County Average soluble sulfate content as micrograms of sulfate per collector per rainfall
CONCLUSIONS
The atmospheric concentrations of gaseous fluorine contaminants present in the vicinity of the twelve air-sampling sites did not of themselves establish the minimum concentration of gaseous fluorine compounds in the air required t o produce typical fluorine damage, which has been described by Miller, Johnson, and Allmendinger (8,9), De Ong ( d ) , La Fleur ( 5 ) ,and Laurie ( 6 ) . The concentrations of gaseous sulfur compounds in the atmosphere of the damaged area were found t o be too low to be an independent factor in the pine tree damage. However, the possible synergistic effects of subdamage concentrations of sulfur dioxide in admixture with gaseous fluorine compounds must be thoroughly investigated before any conclusions concerning the possible causes of the pine tree blight can be drawn. Controlled fumigation experiments must be conducted t o establish the minimum concentrations of gaseous fluorine compounds and gaseous sulfur compounds, either singly or combined, which will produce typical damage t o a number of types of vegetation, including ponderosa pine and gladioli. These investigations are being currently conducted a t the State College of Washington.
700pg a
greater
Figure 18.
Rainfall Studies in Portion of Spokane County
Average soluble fluoride content as micrograms of fluoride per collector per rainfall
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Vol. 44, No. 6
Air Pollution Correlation of the macro- and micrometeorological characteristics of the pine blight area with the concentrations of acid gases found in the atmosphere explains the shape of the area of visible damage. The cross-sectional concentrationp atterns obtained by analysis of rain-water samples collected a t 82 locations during the months of September and October 1950 show that the major source of fluorides in the north Spokane area coincides with the center of the observed ponderosa pine damage; that significant quantities of fluorides do not originate outside the area t o be transported into the area by the winds (the one area of high fluoride outside the blighted area may be explained by the proximity of a portland cement operation and the resultant leaching of fluoride from the cement dust deposited in the rain collector); that the sulfur dispersion pattern does not coincide with the fluoride patterns; that sulfur found in the rain water resulted from industrial operations, a burning trash dump, domestic heating, and internal combustion engines; and that fluorine found in the rain water resulted primarily from industrial operations. ACKNOWLEDGMENT
Many individuals and organizations have given assistance, suggestions, and cooperation during the investigation of the role of atmospheric pollution in the ponderosa pine blight. A complete listing of all groups and individuals would he voluminous; however, special mention Fhould be made of the following: The City of Spokane, Spokane County, and the Washington State Department of Agriculture through the Inland Empire Pine Damage Committee for the financial aid which helped make the investigation possible. Technical personnel of the Division of Industrial Research shops.
Citizens of Spokane County who generously allowed various pieces of sampling equipment t o be located on their roperty. Wind direction and speed data from Kaiser Aruminum and Chemical Corp., Spokane, Wash. Pacific Northwest Alloys, Inc., Spokane, Wash. Phillips Petroleum Co., Spokane, Wash. Bud’s Welding and Auto Repair, Spokane, Wash. Damage pattern map by C. G. Shaw. Robert McComb, officer in charge, U. S. Weather Bureau, Spokane Airport. LITERATURE CITED
(1) Assoc. Offic. Agr. Chemists, “Official and Tentative Methods of
Analysis,” 6th ed., pp. 477 ff., 1945. (2) De Ong, E. R., PhytopathoEogy, 36, 469-71 (1946). (3) “International Critical Tables,” Val. 111, p. 28, New York.
McGraw-Hill Book Co., 1926. (4) Katz, Morris, IND. ENG.CHEM.,41, 2450-65 (1949). (5) La Fleur, W., Monthly BuEl. Ohio Florists’ Assoc., No. 232, (January 1949). (6) Laurie, A,, Hasek, R. F.. and La Fleur, W., Proc. Am. SOC.Hort. Sci., 53, 466-72 (1949). (7) MacIntire, W. H., et al., IND. ENG.CHEM.,41,2466-75 (1949). (8) Miller, V. L., Johnson, Folke, and Allmendinger, D. F.. Phytopathology, 38, 30-7 (1948). (9) Ibid., 40,239-46 (1950). (10) “Scott’s Standard Methods of Chemical Analysis,” 6th ed., N. H. Furman, ed., Vol. 1, p. 925, New York, D. Van Nostrand Co., 1939. (11) Shaw, C. G., Abbitt, W. H., and Adams, M. F., personal communication. (12) Thomas, M. D., and Hill, G. R., Plant Physiot., 10, 241-307 (1935). (13) Willett, H. C., “Lectures Presented a t Inservice Training Course in Air Pollution,” p. 26, Ann Arbor, Mich., University of Michigan, 1950. RECEIVED for review June 5, 1951. ACCEPTEDMarch 31, 1952. Presented before the Division of Industrial and Engineering Chemistry at the 119th Meeting of the AMERICANCHEMICAL SOCIETY, Cleveland, Ohio.
Measurement of Atlnospheric Fluorine 1
ANALYSES OF RAIN WATERS AND SPANISH MOSS EXPOSURES W. H. MACINTIRE, L. J. HARDIN, AND WINNIFRED HESTER The University of Tennessee Agricultural Experiment Station, Knoxville, Tenn.
Rainfall collections at six points were analyzed to measure the periodic washdowns of fluorine from the atmosphere in relation to the locations of operations that emit fluoric effluents, and charges of Spanish moss were exposed to measure progressive intake of fluorine from the atmosphere. Longer intervals between rainfall caused higher concentrations of fluorine at the several locations. Proximities of samplings to sources of emissions were reflected by higher concentrations of fluorine in rain waters. Exposures of Spanish moss acquired substantial progressive enhancements in fluorine uptake at points near those where fluoric emissions occurred. The findings demonstrate that these two feasible and economical procedures can be implemented in parallel to establish whether a particular locale is subject to atmospheric pollution and the degree of pollution. Through integration with meteorological records, the determined occurrences of fluorine in the rain waters might indicate the origins of the contaminative effluents.
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I
N 1943, according to Sappington ( 5 ) , flouric effluents were
being emitted to the atmosphere by 29 industrial operations in the United States. Such emissions occur a t certain locales of two Tennessee counties, in which are located experiment station farms of The University of Tennessee. The farm in Blount County is about 6 miles distant from the aluminum production operations at Alcoa and is located on a soil formation that has a meager content of fluorine; but the farm in Maury County is within a 10-mile radius of several manufacturing operations for production of phosphorus and phosphates and is located on the Maury soils that are characterized by their unusual contents of phosphorus and fluorine. (Use of the word “fluorine” in this text connotes the occurrence of that element as a component of some fluoric combination.) Because of the many contentions that fluoric emissions have caused injurious effects upon plant and animal life in certain locales of those two counties and because of the direct concern of the university, an over-all study of the effluent problem was inau-
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