USE OF GASEOUS TRACEBi
FOR AIR POLLUTION STUDIES
IN URBAN AREAS
J. BINENBOYM, I. GILATH, M. MEUZER, CH. GILATH. A. LEVIN, M. RINDSBERGER. and A. MANES
Report to the National Council for Research and Development
Israel Atomic Energy Commission and Israel Meteorological Service 19 7 5 USE UK GASEOUS 1.:ACERS FOR AIR POLLUTION STUDIES IN URBAN AREAS
J. Binenboym and T. Gilath Inorganic and Physical Chemistry Dept. Soreq Nuclear Research Centre
M. Meltzer, Ch. Gilath and A. Levin Isotope Applications De.pt. Poreq Nuclear Research Centre
M. Rindsberger and A. Manes Israel Meteorological Service Beit Dagan
Report to the National Council for Research and Development
Soreq Nuclear Research Centre Israel Meteorological Service Israel Atomic Energy Commission Ministry of Transportation
August, 1975 I.:ONTI:NTS
1 . INTRODUCTION 3 2. METHODOLOGY 6 3. MODELS FOR THE COMPUTATION OF DISPERSION OF POLLUTANTS EMITTED BY POWER PLANT STACKS 8 4. EXPERIMENTAL 11 4.1 Analytical 11 4.2 Tracer injection and sampling 13 4.3 Field experiments 14 5. RESULTS 16 6. ERROR ANALYSIS 18 7. DISCUSSION 21 8. CONCLUSIONS 28 APPENDIX 31 REFERENCES 33 TABLES 35 FIGURES 49 - 1 -
AJ.SlKAi i
A tracer technique, using the inert gas SF , was apolied to determine the dispersion of the stack el fluents frcm the Reading povcr plant, ur.i.., -.-' '), In the greater Tel-Avi\ ire,i. The contribution :--i the power plant to ground level concentratic .s of S0? was assessed by comparing the measured SO., values with t'nse calculated from the
SF, dilution and the SO., emission concentration.
It is shown that at some measuring stations the ground level
SO, concentrations are greatly enhanced from sources other than the power plant.
''•y, ground level concer.t rat iont" computed using a t.aussian
iLi'usion model '..ere found to bo lu'..cr than the measured values. 1. IN'IRODUCTLON-
In urban areas there are a multitude ot sour'.fH emitting pollu- tants under different, conditions. The ground level concentration of air pollutants is determined by the contributions of the various sources, and the dispersion and possible disappearance of the pollu- tants during their travel from the point of emission to the point of interest. Efficient monitoring and control ot air pollution calls for prediction and measurement of each of the above factor? Gaseous tracers may he instrumental in achieving this goal.
When several sources are polluting a given .area, it is of interest to establish the specific contribution of each source to the concen- trations measured. Thus one becomes interested in specifically labelling the pollutants emitted from a given source, i.e. tracing its pollutants. The interest in atmospheric tracer-::- started between World Wars I and II in connection with atmospheric dispersion studies Chemical warfare groups were among the first to become interested in tracer techniques for simulating the dispersion of chemical war agents. Later the construction of atomic energy installations (reactors, fuel repiocesslng plants, etc.) and the general interest in air pollution resulted in development of these techniques.
The different tracer techniques in use until the mid-sixties have been reviewed by Slade . Oil fog, aerosols and fluorescent powders, rather than gases, were used most often in tracer studies. Generally the particle size was limited to about 10 microns and it was accepted that the dispersion of the particulate aerosol actually represented the dispersion of a gas. A considerable number of the diffusion and tranrport experiments performed with particulate tracers are reported by Slade^ . It is of interest to note that the great majority of dispersion coefficients and/or standard deviations used in connection with dispersion models today resulted from measurements performed with particulate tracers . Among the particulate tracers, inorganic fluorescent particles, such as zinc cadiuni sulfide, wore generally used in urban areas However, continuous use of this tracer is limited because ot its tosicity C) . Other problems connected with participate tracers are the loss by falLout and impaction, instability in the atmosphere (loss of fluorescent activity of small particles after exposure to sunlight), etc. The wide acceptance of particulate tracers was due to lack of a suitable gaseous tracer, measurable to high sensitivity and not occurring in nature.
Gaseous air pollutants are transported by turbulent dispersion and therefore the molecular identities of the tracer and the traced ft s compound are of no importance, Kr was used as a tracer in disper- sion studies from ground sources at relatively short distances, i.e. less than 1 km . For distances greater than 1 km very high activities 41 would be involved. Ar produced in nuclear reactors was detected at downwind distances as far away as 6 kin . However, its use is possible only in connection with the stacks of nuclear reactors.
Preliminary tests, "-I960,with halcgenated compounds such as freons and SF. proved their suitability as atmospheric tracers ' . SF, was found to be the most suitable tracer among thesa compounds. It was first suggested bv Collins et al. , and .later advocated by 8 9 10 Turk Et al.*" "*. demons et al.^ \ Hawkinr/ \ Dietz and Drivas and Sh.iir ' also used this tracer in their work.
SF, is not found in nature and its main use is as an insulator b in very high voltage transformers. It is chemically inert, stable towards hydrolysis, oxidation and photolysis, and non-toxic, odorless <13) and colorless . It is not subject to fallout or other atmospheric removal processes ' . SF can be easily released into the atmos- phere at a well-controlled rate. It is inexpensive, costing about
$ 7 (U.S.)/kg. The background level of SFft is negligible, i.e. below 10 cm SF-/cm air '. SF, can be detected to a very high sensitivity using a gas chromatograph equipped with an electron capture detector. Direct determination of SF during the early studies was limited to relatively lov sensitivity . It's detection involved preconcentration of the air samples to he analyzed either !y freeze-out or by adsorption and concentration on activated charcoal'' ' . At present however, it is possible to detect SF directly in concent rati< r. Lower than 10 ' cm SF,/cm air ' ' . A i rl.orrie chromatr'graphs designed for real-time studies of diffusion and plume transport have also been successfully developed ' '. !n conclusion, the develop- ment of very sensitive gas cliromatographic techniques foi determining traces of SF can be considered as a bieakthrouau in the use oi gaseous tracers for air pollution studi s.
Thti aims o£ the present research were to work out a technique for tracing the stack effluents of power plants, over long distances. This involves working out the gas chrotnat.ograpnic technique for measurement of very low concentra-
tions of SFr in the air. 6 to develop a tracer technique for identification of the contribu- tion of individual sources in the air pollution in an urban area;
specifically to determine the contribution of the Sfl0 emitted by the Reading D power plant to the SO- concentration measured in the greater Tel-Aviv area. This is important since of all the S0~— emitting sources in the Tel-Aviv area only the Reading D power plant is provided with means for controlling the emission.
tc gain information on the relation of measured tracer concentra- tions in an urban area to those predicted by models.
- to assess the potential of the technique based on gaseous tracers for the determination of the pollutant disappearance rate.
Reading D power plant refers to the whole Reading power station complex (i.e. units B+D). All units discharge effluents through a common stack. - b -
2. METHODOLOGY
tracing the stack effluents of power plants requires essentially the injection ot the tracer into the stack, knowledge of the effluent ilow rate, temperature and composition, sampling of air at different locations and measuremer _•£ c . r.r er concentration in the samples. The tracer injection can u<- ^L...~,. instantaneous or continuous.
Instantaneous injection results in a tracer puff, the concentra- tion of which has to be measured both in space and in time. Measuring . C dt (C i«* the concentration of the tracer as a function of time) o tr tr at a given location enables one to calculate the steady state concen- tration of any component of the effluent into which the tracer is injected . This calculation assumes however steady state conditions (i.e. no change at all in. wind speed and direction) which are almost impossible to achieve practically. This is the reason why only a few instantaneous injection experiments were performed in atmospheric dispersion studies . These fex^ experiments were aimed at obtaining standard deviations for instantaneous release conditions or for simulating accidental releases of pollutants. The continuous injection method requires that the injection be performed over a period sufficiently long so that fluctuations in wind direction and/or wind speed average out, yet short enough so that the same average wind direction and velocity are preserved during the entire injection and sampling time. It is common to perform the injection over a time period equal to 1-2 times the travel time from the source to the most distant sampling station . If the average wind velocity is about 5 m/sec and one is interested in working over distances of up to 10 km, injection time should be between 0.5 and 1 hour provided the average wind direction and speed does not change during this period of time. The majority of atmospheric dispersion parameters are reported in the lzLtidCure for 10 minute sampling (18i times . The correction of dispersion coefficients and/or concen- trations for sampling times different from 10 minute is made according - 7 -
/ 1 O \ to Cramer's power law ' , The concentration is inversely proportional to the sampling time raised to the power of 0.2. Injecting the tracer into the stack effluent and measuring its concentration in the ambient air at different distances from the source enables one to determine the dilution of the effluent from the source (the stack) to the respective sampling points. Flow rates of tracer and stack effluents have to be known. Knowing this dilution and the emission concentration of any pollutant (a component of the stack effluent) one can immediately arrive at the concentration of this pollutant at the location of interest, neglecting the possible disappearance of this pollutant. A comparison of this concentration with the actually measured pollutant concentration permits assessing the contribution of the given stack (source) to the pollutant concen- tration at the point of interest. This is basically the principle of the tracer method we developed for the identification of the contribution of individual sources to the air pollution in an urban area.
Our interest WdS in determining the contribution of the Reading D power plant to the S0~ concentrations in the Tel-Aviv area. The emission concentration of S0~ is about 1500 ppm. The maximum permissible concentration of SO_ for a half hour sampling time is 0.3 ppm. Accordingly, one is interested in measuring the contribution of the power plant, down to a dilution of about 10 of its effluents (i.e. down to about 0.015 ppm SO,). Taking into account the flow rate of the stack gases (at 250 MW-500 MW power production) and the ultimate sensitivity which we attained in the detection of SF, -12 3 3 (i.e. 5x10 cm SF,/cm air), this requirement implies the injection o of about 10 kg SF,/h. The actual injection time was 1.0-1.5 h.
The sampling.sites, located within a range of 2-11 km from the power plant have to be selected according to the wind direction, and the available pollutant, in this csse S0_, monitoring stations. Air samples are to be collected at a constant flow rate over a period of - s -
JO minutes tor eaoh sample- SO., measurements are to be performed during the same period. Simultaneously, meteorological balloons are released to provide the wind profile. Additional meteorological information such as temperature profile, radiation and cloudiness are obtained from the nearest meteorological stations, in our case from the Meteorological Service at Beit Uagan (located 12 km south east ,u the power plant) and the Sde Dov airport adjacent to Reading.
Tracing the stack gas with SF can provide information on the disappearance rate of a nonconservative pollutant emitted from the given source (stack). "X is essential that this source be the only one in the given area. A tracer experiment has to be performed (e.g. by the continuous injection method) and the pollutant concentra- tion downwind has to be measured and calculated from the tracer results (i.e. via the dilution and the emission concentration, as previously explained). Due to disappearance the actually measured concentrations of the pollutant turn out to be less than those calculated from the tracer data. The discrepancy between these two concentrations will increase with the distance from the source, i.e. with the increase in travel time. Investigating this discrepancy as a function of the travel time permits determination of the pollutant's disappearance rate(17).
3. MODELS FOR THE COMPUTATION OF DISPERSION OF POLLUTANTS EMITTED BY POWER PLANT STACKS
One of the aims of the present research was to check the adequacy of applying a Gaussian diffusion model to predict the pollutant concen- trations from a single elevated source in the greater Tel-Aviv area. Dispersion models for pollutants emitted from tall stacks (height h) require the knowledge of the effective height, H of the plume. Thus, for estimating the plume rise, Ah, we adopted a model formulated (19) by Turner . According to this model, for neutral and unstable conditions, the final plume rise occurs at a distance xf from the source and is given by
Lh wliere
.T -T F = 3.12 V '-!—• (2)
• ' s '
x* = 34 F2/5 (for F >, 55) (3)
x* = 14 F5/8 (for F < 55) (4)
U, = wind speed at stack height (—2-) n sec
Vf = is the volumetric flow rate of stack
gases (m /sec), i.e.
V = stack gas exit flow velocity (m/sec) s
d = inside diameter at the top of the stack (m)
T = ambient air temperature ( K.)
T = stack gas exit temperature ( K)
The distance at which the final, plume rise occurs is given by
xf = 3.5x* (6)
For distances x 1/3 2/3 x Ah = 1-6? u (7) The etteccive stack height taken in further computations .' H = h + Ah (8) GrounJ level concentrations of pollutant emitted from the stack can be calculated by using the Gaussian plume dispersion model, as des- (18) cribed for example by Turner : exp[- J i~)2) expl- j (f-)2] (9) y z z y \(x,y,O,H) is the ground level (z=0), concentration [ug/m ] of pollutant, at coordinates (x,y,0) for an effective height H. The coordinates of the source are (0,0,H). Q is the source emission rate (ug/sec), u is the average wind velocity over the layer in which the dispersion takes place (m/sec), a and o are the lateral and vertical standard deviations, respectively, (sometimes also called dispersion coefficients), x is the downwind distance from the source and y is the crosswind distance, All distances are in meters. In general a and a depend on the Pasquill atmospheric y z stability conditions and the distance x downwind. The atmospheric stability conditions are defined according to the surface wind speed, solar radiation and cloudiness '. Six stability categories were defined by Pasquill, A, B, C, D, E, F, where A is the most unstable and F is the most stable condition (18^ The Gaussian dispersion model Eq. (9) is based among others on total reflection of the plume at- the earth's surface (no deposition or reaction is allowed for). Equation (9) does not assume any upwards limitation in the growth of the plume. However, it is rather frequent that the plume becomes trapped between the ground surface and a stable layer aloft, bnder these conditions, multiple eddy reflections take place from both the ground and the stable layer. The base of the stable layer is at a height L (m) above the ground. Turner gives - 11 - an equation for taking these multiple reflections into account. This equation for ground level concentrations (z=0) becomes X(x,O,O,H) = v '"2exp[-( ' l > y z z (10) where J is the number of reflections. J=3 or 4 should be sufficient to take into account the relevant reflections. Turner also suggests a short-cut through this computation by assuming no effect of the stable layer aloft until a distance x. is reached at which o = O.47L. It is assumed that at this distance, x^ , the stable layer begins to affect the vertical distribution so that at the down- wind distance 2xT uniform vertical mixing takes place and the Li following equation can be used for x > 2xT and 0 .< z< L x(x,y,z,H) = " exp[- y (2-) ] (11) /2TT O LU y y For distances x < x < 2x. an intermediate situation occurs, since homogeneity has not yet been achieved. 4. EXPERIMENTAL 4.1 Analytical 4.1.1. SF, measurements — (j ' ' " SF, concentration was measured using a Hewlett-Packard Model b 5713A electron capture gas chromatograph. The detector has a Lci mCi Ni radioactive source. The emitted beta particles result in the formation of secondary electrons from the carrier gas (argon/methane). A potential is pulsed across the cell with automatic frequency modu- lation in order to maintain a constant value of the "standing current" iuring passage ot the gas sample through the cell. The automatic change in pulse rrequency is proportional to the concentration of the sample. The linearity ol this instrument is better than i5% at any convenient sample concentration, within a range o£ 10 . An UC filter circuit was added to the electrometer output to provide a more favorable signal-to-noise ratio. The output signal from the electrometer was monitored with .1 Yokugawa mule lvolta^, i range recorder. Several types 01 columns were prepared by us and checked for their performance. The optimal one used in these experiments was a 17 ftxl/8 in. stainless steel tube packed with a specially treated 5A molecular sieve. The carrier gas was a mixture of 90% argon and 10% methane. The instrument was connected to the manifold of a stainless steel vacuum line through a multiport gas sampling valve. A constant volume loop of 5 cm was used for injection of the sample. The pressure of injected sample was controlled by a high accuracy pressure gauge. The chromatograph was calibrated with gas mixtures ranging from 10 - 10 cm SF,/cm air. The gas mixtures were prepared by a volume pressure dilution technique in a stainless steel vacuum line. Extreme precautions were taken to avoid manifold or container "memory" of SF, traces. D Dilutions were also made in a sealed room provided with mixing and exhaust facilities. The dilutions were cross-checked with a oc radioactive tracer ( Kr). The ultimate sensitivity achieved was 5xl0~12 cm3 SF,/cm3 air. 0 4.1.2. £30- measurements The SOj concentrations were measured only at those sampling sites where S02 measuring stations already exist, as part of the Tel-Aviv monitoring system (see Table 1 and Fig. 1). SO. concentra- tions in air were measured by a Wosthoff "Ultragas U 35" analyzer. The instrument operates based on conductivity measurements. With this gas trace analyzer, continuous and constant streams of air and - 13 - of reaction solution react with eacn other in a chamber. The electrical conductivity of the reaction liquid changes with the concentration of the gas to be measured (SO ). The chemical reactions involved are: Due to the high mobility of H-ions from the sulfuric acid formed, it is possible to measure trace quantities of SO . The measured values of S02 recorded by means of a potentiometric chart recorder are also integrated giving average readings for a period of 30 minutes. These readings are printed out by a special counting device. The instrument has two temperature compensating resistances in the measuring circuit. These balance out to zero any variation in the difference in conducti- vity due to temperature differences, as well as the influence of humidity of air, i.e. water vapor pressure in the measuring lir.es. 4.2. Tracer injection and sampling The injection of SF, was made at the Reading D plant. A -1" pipe was available for access to the flue gas in the ducts at the entrance to the stack. The tracer was fed from two manifolded cylinders of SF,. A precise rotameter was used to maintain a constant flow rate of 31.6 liters SF,/min at atmospheric pressure and 21 C. The air samples for laboratory analysis were collected in one liter stainless steel canisters. Stainless steel was reported to have the lowest memory for SF, . The samplers were evacuated before each experiment and checked for traces of SF,. In case the results were not satisfactory, the car.isters were flamed, evacuated and swept with nitrogen. This procedure was repeated several times until no traces of SF, ' could be detected. Air samples were continuously collected for 30 min through sonic orifices prepared and calibrated in our laboratory. The performance of the orifices was checked before each field experiment. - 14 - !_p co nine St, sampling stations were allocated for each experiment. These stations were positioned on the ground in the direc- tion of the plume axis, and on line1? perpendicular to the axis, and whenever possible, at relevant SO, monitoring stations. The loca- tions of all sampling stations used throughout experiments TA1-TA4 can be seen in Fig. 1 and Table 1. The stations used for each experi- ment are given in Tables 9-12 and 13-16. The azimuth of the plume axis was estimated from the average wind direction between ground level and 500 m height- Two consecutive 30 min samples were collected at each station (except for experiment TA1 when 3 such samples were taken). The sampling starting time took into account the travel time from the source to the sampling station. This time was calculated from the distance of the station from the stack and the average wind velocity. Prior to injection, several samples were collected for background measurements. A.3. Field experiments Four experiments, TA1, TA2, TA3 and TA4 were performed on 27.6.1974, 15.7.1974, 33.7.1974 and 8.9.1974 respectively. The operating conditions of the Reading D power plant and the injection times are given in Table 2. The stack gas emission rate was between 1.52x10 m /h and 2.58x10 m /h at a mean stack ga~ temperature of 165°C. The injection lasted for 1-1.5 hours. The emission of SO- was between 4.3-7.2 ton/h. Tue experiments were performed under average summer conditions. The synoptic maps for each of the experiments indicate the presence, of a low level trough which induces a weak cyclonic circulation. Thie trough in the lower layers, extending from the Persian Gulf, is a typical summer phenomenon. General weather conditions during the experiments are given in Table 3. Temperature profiles were measured at Beit-Dagan and are given in Figs. 2-5. There was a stable layer aloft, the base of which was - 15 - at a height of about 400-500 m. The stable layer was seen to be rather weak during experiments TA1 and TA4. it was much more pro- nounced during experiments TA2 and TA3, probably due to the more pro- nounced ridge in the upper layers at the time of the experiments. Wind profiles were measured in the vicinity close to the Reading power station by tracing slow-rise pilot balloons. At least three balloons were released during each experiment. The results of these measurements are shown in Figs. 6-9 and given in Tables 4-7. It can be seen that between 350 and 500 m there is a sharp change in wind direction and/or speed. This indicates a change in the thermal stability at these heights, which may be due to the synoptic situation and/or the sea breeze effect. The discontinuity between the lower and upper layers was taken into account estimating the height of the base of the inversion layer, L. The stability conditions during experiments TA1 to TA4 were determined from the vertical temperature profiles (measured at Beit Dagan, see Figs. 2-5), surface wind speed (measure-1 at Sde-Dov, near Reading) and global radiation (as measured at Beit Dagan). These conditions, as well as the height of the base of the stable layer, are given in Table 8. The fixed S0_ monitoring stations are located on 4 axes, drawn from the Reading D power plant. These axes lie on the following azimuths: 2Al°-243°, 290°, 328°-335°, 350°-352°. No mobile S02 measuring stations were available for the present study. The experi- ments, aimed at determining the contribution of the Reading D power plant to the SO, concentration in the greater Tel-Aviv area, were intended to be performed with the wind blowing in the direction of SO- monitoring stations. This is, however, quite a difficult cons- traint, since the wind during a typical summer day veers from SW through W to NW. The duration of a steady wind blowing in the direction of S0? stations is not always sufficient for our requirements as expressed in section 2. The present locations of S0? monitoring stations do not coincide with the highest wind frequency. Thus, in experiments TA1, TA2 - 16 - and TA-i the plume axis did not. coincide wtch any ot the axes of the SO, monitoring stitions. Only some of the SF, measuring stations located at cross-wind directions, coincide with the SO monitoring stations. 5. RESVLIS Concentrations of SF and S07 measured during experiments TAl to TA4 are given in Tables 9-12 These tables also contain cal- culated SO-, concentrations for the different stations. The calcu- lations were based on the emission concentrations of SO., and SF, I b (at Reading D) and the measured SF, concentration at the different sampling- '.^ee appendix for sample calculation ). S0~ concentrations at emission are given in Table 2. These concentrations were computed from the fuel consumption, the sulphur content of the fuel and the stack gas flow rate. The emission concentrations of SF, were computed from the flow rate of SF,. injected into the stack and the stack gas flow rate. The SF, emission concentrations were 1.743x10 , 6 ? 6 6 3 3 1.7O4xlO~ , l.: 4xl0" and 1.074xlCf cm SF6/cm stack gas during experiments TAl, TA2, TA3 and TA4, respectively. -12 3 3 Due to the ultimate sensitivity limit of 5x10 cm SF,/cm air o there is also a threshold of calculated SO^ concentration, below which we cannot compute the S0_ concentrations from SF, measure- z o ments as explained above. This threshold is 11, 12, 12 and 3 19 ug S02/m air for experiments TAl, TA2, TA3 and TA4, respectively. The various thresholds are due to the fact that a constant flow rate of SF, was maintained at injection, while the stack gas flow rate changed from experiment to experiment (see Table 2). The differences between measured and calculated SO. concen- trations in Tables 9-12 may be due to contributions of SO, from sources other than the Reading D power plant and the possible dis- appearance of S0_. - 17 - The rise o£ the plume above the stack was computed according to Eq, (1). The average temperature of the stack gases of Reading D power plant weighted according to the relative stack gab flow rates was used in these computations (see Table 2). Thus, it was assumed that the individual plumes resulting from the 3 riucts in the stack of the Reading D power plant converge into one plume, having this average weighted temperature. The rise was found to be: TA1-300 m, TA2-350 tn, TA3 first sampling-300 m, TA3 second sampling-250 m, TA4 first sampling-650 m, TA4 second sampling-320 m. Accordingly, the effective plume height was found to be: TA1-450 m, TA2-5OO m, TA3 first sampling-450 m, TA3 second sampling-400 m, TA4 first sampling-800 m and TA4 second sampling -470 m. In those cases in which the effective plume height exceeded the height of the base of inversion, L, (see Table 8), L was taken to be equal to the effective plume height (i.e. H=L). This was che case in experiments TAl, TA2 and TA4. Expected concentrations of SF, were computed for the different sampling stations, based on Eq. (10). The results of these computa- tions, as well as the corresponding measured concentrations of SF, are given in Tables 13-16. The following data were used in these computations: SF, source emission rate, 0=3.2x10 ug/sec in all experiments, o wind speed and directions were averaged up to the effective height and are given in Tables 13-16. (18*1 o and o dispersion coefficients were taken from Turner They are given for a sampling time of 10 min. Therefore, also the ground level concentrations along the plume axis (center line) and the concentrations at the actual sampling stations, i.e. X(x,0,0) and x(x.y,O"), respectively, as given in Tables 13-16, are values expected for 10 minute sampling periods. The SF, concentrations x were measured by sampling over periods of 30 minutes and are given as y d in Tables 13~16- - 18 - In order to compare these values wi.h the above-mentioned computed values i, i or 10 minutes), the measured values were corrected for a 10 minute sampling, as indicated by Turner : (12) Ho • <3o[T5: '" Values oi X.- ace also given in Tables 13-16. The ratios X, rv/x(xiy|O) are indicated Ln Tables 13-16 te serve as a comparison of measured and expected Si' concentrations, In experiment TA3, measurements of SF, concentrations were made on a line perpendicular to the plume axis, at a distance of 5750 m from the source. The SO., concentrations on this line, computed from SF, measurements, are given in Fig. 10 for the first and second samplings, o was estimated in both cases to be about 500 m (for a 30 min sampling time). a , corrected for 10 min, accordingly becomes fio) 500 x \~\ = 450 m This value is reasonably close to the value of 510 m predicted by Turner(18). Ground level SO. concentrations measured and computed from SF, measurements as a function of distance from Reading D, experi- ment TA3, are given in Fig. 11. This figure is based on data collect- ed at the existing measuring stations, which do not necessarily lie on the plume axis (see Table 15 for the respective crosswind dis- tances, y). Two curves are given in Fig. 11, i.e. for the first and the second samplingst respectively. 6. ERROR ANALYSIS The possible errors in predicting the concentration of the pollu- tant according to the dispersion model used in the present study are: - 19 - a. Inaccuracies in wind measurements, made using pilot balloons, li. inaccuracies in the calculated effective plume height H. c. inaccuracy in the determination of the height of the base of the upper inversion layer L. d. inaccuracy in the determination of the stability conditions. A discussion of these factors and their influence follows. Experiment 1A3 is used as a basis for discussion. Inaccuracies in S0_ and SF, measurements are considered to be negligible in comparison with the above mentioned parameters. a. Wind measurements were made once every 20-30 minutes. No con- tinuous information is available on the average wind direction during the experiments and at the heights of. interest. Therefore results obtained by balloons were considered to be the actual averages. Fluctuations and/or errors of 2 ~k in the wind direction were consi- dered. The error between the actual and assumed plume axis results in a possible error of Ay in the crosswind distance of any given point from the axis, y. The effect of this error upon the predicted concentration is given by exp[- -r (—*-) ] and falls in the range of °y 10% - 30% for 2°-4° errors in wind direction measurements over dis- tances of 3.9 km to 11 km. This estimate is based on Pasquill stability conditions C. Errors in measured wind velocity can be of a few tens of percent at most and this would roughly also be the error in expected pollutant concentration, see Eqs. (9), (10). There is also an indirect error in the calculated concentration, which enters in the calculation of the plume rise, see Eq. (1). This effect would be important mainly at distances for which x •- x. and to some extent for x, < x < 2xL« An increase in the wind velocity would result in a decrease in Ah, and consequently an increase in the concentration at the ground level. This indirect effect would be partly cancelled out by the direct effect o the decrease in the concentration due to the increase in wind speed. b. The different methods available for calculating the plume rise are known to provide quice different results. No measurements of plume rise were performed during the present study. However, using a Ah smaller than the one employed in the present work would result in an increase in the calculated concentration at locacions relatively close to the source, Ue. at which the plume is not yet affected by the in- version layer, x - x ). This increase would gradually decrease for distances x • x. and disappear beyond Zx^ . For example if the effective plume height was 350 m instead of 450 m at sampling station 72, at a distance of 3.9 km from the source the x, g/x'.Xiv»G) ratio would be 2.5 instead 4.9 (see Table 15). For this experiment x =4.3 km. It can therefore be concluded that errors in the effective plume height can have quite a significant influence on the predicted pollu- tant concentrations at distances close to the source, i.e. at x < x^. c. The inaccuracy in the determination of the height of the base of the upper inversion layer L could be somewhat important at relatively greater distances from the source (i.e. at x > x. and mainly x > 2xT ). A decrease in L would result in an increase in the expected concen- tration, see Eq. (11). During experiment TA3, L was 500 m and errors in L could be of the order of magnitude of 100-200 m at most, which would effect a change of ""20-40% at most in the expected concentration, at x > 2x, , which i.i our case means x > 8.6 km. It should be recalled here that the above value for L is based on measurements at 13:00 at Beit Dagan, while the actual L would be influenced by the sea breeze, possible "heat island" effect over Tel-Aviv, etc. It is reasonable to believe that L in the area of interest should be greater than 500 m. The "heat island" will usually cause a rise in the height of the base of the inversion layer. d. All results indicated in Table 15 were based on Pasquill stability conditions C. If we consider stability conditions B instead of C at distances x < xL an increase in the ground level pollutant con- centration is found. At 3.9 km from the source, this increase would - 21 - amount to about 45% . In more general terms, transition from stabi- lity conditions C and B involves an increase in z and ; . This y z increase will result , for x < x , In a decrease in the maximum con- centration along the plume axis (see the Gaussian model Eq. 9), but It will increase the exponent containing the deviations (both in y and in z) from the plume axis. Thus, the total result will reflect both effects and cannot be generalized, since it depends also on y/o (H-z)/; and (H+z)/j . y i. z At distances x > 2x the effect of transition from stability conditions C to B can be seen from Eq. (11). The increase in a will result in a decrease in the concentration along the plume axis, however, for locations off the plume axis, also y/o , occurring in 1 y 2 y exp[- -r (~•) ] has to be taken into account. For station 45, 7.1 km I Oy from the source, the transition from C to B conditions results in a decrease of 25% in the computed concentration of pollutant. If the stability conditions during experiment TA3 would have been D instead of C, x. would have been 26 km instead of 4.3 km! Thus, all sampling points would be situated at x <• x and most of I_i them at x << x. . Accordingly, the computed concentrations at these stations would be very low. At station 45 (7.1 km from the source) -4 3 the computed concentration is 7x10 ug SF,/m while the measured value was between 0.85 - 1.26 ug SF,/m . This definitely confirms that stability conditions could not have been D during experiment TA3. 7. DISCUSSION The results described above are discussed here essentially in terms of the contribution of the Reading D power plant to the measured S0o concentration, measured SF, concentrations as compared with those predicted by the dispersion model, and disappearance of S0_. - 22 - Experiment TA1 In this experiment the wind direction did not coincide with any of the axes of the S0_ monitoring stations. The wind directions for the 3 sampling periods were 278° , 270° and 274 respectively. The only SF,. sampling stations on this axis, or very near to it, were 20 and 21, at azimuths 270° , 269° and distances 3250 m and 5400 m respectively. Calculated S09 concentrations for these stations (20 and 21) were relatively high (see Table 9). The other stations were located very far from the plume axis arJ low SF, and SO, concentrations were measured. At these stations very low (10-20 yg/m ) S00 concentrations were measured, and they were higher than the cal- culated values. This discrepancy can be due to either contributions from sources other than Reading D or inaccuracies in the S0_ measure- ment at such very low concentrations. A comparison of measured SF, concentrations and concentrations predicted according to the model (as described in section 3) can be made only at stations 20 and 21. As seen in Table 13, thp measured values are higher by a factor of 1.3-3.7 than the calculated ones which is fairly good agreement. At station 22 this factor is 12. It should be noted that this station is located at the edge of the plume, where y/a = 3, H/a =2. z Experiment TA2 Again in this experiment the conditions were such that the wind direction did not coincide with the available S0» monitoring stations. The wind directions were 305° and 304° for the first and second sampling times, respectively. SF, sampling stations 25, 23 and 26 have azimuths of 306° , 308° and 308°, respectively, and are located 3720, 5100 and 7100 m, from Reading D respectively. The other stations in this experiment ware located relatively far from the plume axis and this explains the very low SF, and calculated SO,, concen- trations. Calculated S02 concentrations for stations number 25, 23 and 26 were relatively high (Table 10). The maximum SF, 6 - 23 - :imcencration was measured at station 23, i.e. at blOO m from Reading D and the concentration at station 26 at 7100 m was somewhat lower. These findings are in good agreement with the predictions of the disper- sion model. For the stability and plume elevation conditions of this experiment, the maximum concentration is expected to occur at 5-7 km from the source, see Turner SO. was measured during this experiment at stations 74, 75, 77 and 78 and in all instances the concentrations were higher than those calculated from SF, measurements. At stations 74, 77 and 78 the SO concentrations arc in the -ange of 15-35 Mg/m and the discre- pancies between measured and calculated S0~ concentrations are for the same reasons as mentioned for experiment TA1. However, at sta- tion 75, the measured SO- concentration is very much higher than the calculated one. This clearly indicates the dominant contribution of a source other than Reading D during the experiment. It should be noted that this station is located in a densely populated mixed resi- dential and industrial area. The measured SF concentrations, for both samplings at stations 25,23 and 26,and for the first sampling only at stations 74 and 24,can be compared with those predicted by the model. At stations 25,23 and 26,the measured concentrations were higher by a factor of 0.95-3,8 than the predicted ones, which is considered reasonable agreement. At all the stations situated very far from the plume axis as can be seen from the y/o ratios, SF, concentrations were very low. It seems that on the plume edges the dispersion model provides lower accuracy than on the plume axis or near to it. Experiment TA3 This experiment was designed and performed taking into considera- tion the conclusions and experience gained in the first experiments. In experiments TA1 and TA2, the plume axis did not coincide with any of the 4 axes of the available SO, measuring stations. Usually during summer, the frequency of wind directions coinciding with the - 24 - axes of the SO, stations is relatively low, and when it does coincide, it is only for short periods of time (1-2 hours at most). Incidentally, this can be seen, not only from wind statistics, but also from records of SO., measurements at the monitoring stations. Ln experiment TA3, it was decided to inject the tracer only when the plume axis (wind direction) coincided with the 241 -243 axis of S07 measuring stations The tracer injection was started once the SO-, concentrations at stations 72 and 73 began tc rise significantly and wind measurements with the pilot balloons confirmed the plume axis to be 241°-243°, or very near to it. The location of the SF. measuring stations during this experi- ment resulted from our desire to compare measured and calculated SO- concentrations at stations 71, 72, 73 (i.e. at a distance of 2050-5750 m from Reading D), as well as to measure the SF, concentration further downwind (up to 10,800 m). In addition, measurements of SF, were performed on a line perpendicular to the plume axis, at a distance of 5750 m from the source, with the intention of measuring the lateral dispersion in the plume, stations 41-44. The actual wind direction, as measured with the pilot balloons during the experiments, was 244 and 238 , for the first and second measuring periods, as compared with the 241°-243 axis at which we aimed. Consequently, the locations of the SF, measuring stations in this experiment were successfully chosen with all samples (nine stations) indicating significant concentrations. The measured and calculated SO- concentrations can be compared at stations 71, 72 and 73, see Table 11. At station 71, located 2050 m from Reading D, the S00 concentration is relatively low 3 (25-35 ug/m ). At station 72, 3900 m from the source, very good agreement between measured and calculated SO, concentrations (differences are about 2-5%) was obtained. At 5750 m from the source (station 73), the measured S02 concentrations were significantly lower (by a factor of 1.48 and 1.32 for the first and second samplings, respectively) than the calculated values. This indicates disappearance - 25 - of SO-. We are aware of the fact that no disappearance could be clearly identified ac a distance of 3900 m from the source (station 72; while the disappearance was very clear at 5750 m. The H/a ratios z are 2.0 and 1.4 at 3900 m and 5750 m respectively, indicating that the SO- concentration in the plume is more affected by ground conditions at distances greater than 3900 m. The above is the only clear indication we found of tli«» disappearance of SO,, during our experiments and no further comments can be made on the rate of dis- appearance and factors affecting it. The dependence of calculated SO- concentration on distance from the source is shown in Fig. 11. This figure is based on measure- ments taken at stations 71, 72, 73, 45 and 46, for which the cross- wind distances y divided by o (i.e. y/a ) range between 0.19 and 1.2. The maximum SO- concentration occurs at a distance of between 4 and 5.6 km from the source. This is in good agreement with the expected position of the maximum according to Turner , consi- dering the conditions of the experiment (see Table 8). From Fig. 11 one can see that the maximum SO- concentration is somewhat further downwind during the first sampling than during the second. This is consistent with the effective plume height of 450 m during the first sampling and 400 m during the second. It is known that an increase in the effective plume height will shift the maximum concentration further downwind. It is interesting to note that at relatively distant station 46, i.e. at 10.8 km from the source, the calculated SO- concentration 3 z reaches a relatively high value of 284 ug/m in the first sampling. The difference in the calculated SO. concentrations between the first and second sampling periods is due to changes in the cross- wind distance of the stations since, there was a change in the wind direction from 244° to 238°. The measured concentrations at stations 72, 73, 45 and 46 relate well to the expected changes due to the alteration in the y/a ratio. The expected ratio of concen- trations during the first and second samplings was l.fi, 1.25 and - Jb - ..J5 for stations 72, ?3 and 45 respectivelyi while the actually neasured ratio was 1.4, 1. t> and 1.4, respectively. As can be seen from Table 15, the measured SF concentrations luring experiment IAJ -ire higher than the calculated ones by a factor >t 0.44 to 7-3, except for stations 71 and 44 (second sampling), tor which the ratio reaches 15 and 18 respectively. In general, V J it can be said that this ratio increases with an increase of / v > and/or H/r , i.e. at locations which are remote from the plume axis. This is expected, since agreement with dispersion models is known to become poorer when the edges of the plume in the y and/or z direction are approached. From Table 15 it can be seen that almost always the measured SF, concentration is higher than the value predicted by the model. Experiment TA4 In this experiment we were interested in studying conditions in the densely populated regions S.E. of the Reading D power plant. It was not considered essential to have the wind direction coincide with the axis of SO,, monitoring stations in this region. The wind direction up to the base of the inversion layer (L=500m) was constant during this experiment (320 ). However, the average wind speed up to 500 m increased from 3m/sec at the beginning of the experiment to 6.2 m/sec at the end. There was also a change in the shape of the wind profile as can be seen from Table 7 and Fig. 9. There was a rather sharp change in wind velocity at a height of about 300 m at the beginning of the experiment which tapered off during the second part of the experiment. The plume elevation Ah was calculated to be 660 m at the beginning of the experiment (i.e. at 3 m/sec average wind speed) and 320 m (at 6.2 m/sec wind speed) towards the end of the ejcperiment. Since the base of inversion was estimated to be at a height of 5Q0 m, it was further assumed that the effective plume height was also at 500 m, i.e. H = L = 500 m. - 27 - According to the meteorological conditions that prevailed during uhe experiment, the stability conditions should be D. Accordingly :t. = 26 km, which would mean very low concentrations close to the source. However, quite significant SF concentrations were measured o at 5090 m and 5250 m distances from the source, i.e. an stations 27 and 28 (see Table 16). Therefore, it was concluded that stability conditions could not be D , hut were probably C, as was assumed for all computations. During this experiment, only one SO. monitoring station (77) was within the plume. At this station the measured SO concentra- 3 3 tions were higher (310 l>g/m and 170 -g/m ) than the values calcu- lated based on SF, concentration (246 i-g/m and 48 ug/m , respec- tively). It can therefore be concluded that this station also measured S0_ from sources other than Reading D. Stations 78, 79 and 80 were outside the plume and the SO. 3 concentrations calculated from measured SF, were low (<19 ug/m ). While at station 79 the measured S0~ is rather close to the back- ground, this is not the situation at stations 78 and 80, where signi- ficant S0? concentrations were measured (104-360 ug/m ), as seen in Table 12. It is obvious that this S0_ originates from sources other than Reading D. Very significant SCL concentrations were calculated from SF, concentrations measured at stations 27 and 28, which were very near the plume axis and at about 5 km from the source. At station 28 which lies on the plume axis, 1158 ug/m and 1410 ug/m (higher than the maximum permissible SO- concentration for a 30 min sampling) were calculated. There is no S0? monitoring at stations 27 and 28. The comparison of measured and calculated (according to the model) SF, concentrations is shown in Table 16. The measured concentrations o are higher (with one exception) than the calculated ones by a factor of 1.7 to 6.2 for stations 27, 28 and 77 which are within the plume. At stations 23 and 26 which are remote from the plume axis, the above ratio ranges between 0.6 and 8.1. - 28 - In spice of Che difficulties encountered in calculating the effective plume height and estimating the stability conditions the discrepancy between measured and calculated SF, concentrationa is within the range of what was found in the other experiments. In all experiments discrepancies between the measured and expected SF,. concentrations were found. An analysis was made in o section 6 in an attempt to assess the errors introduced by the differ- ent parameters entering into the computation of the predicted pollu- cant concentration. However, in this discussion of the experiments it was impossible to identify the contribution of individual para- meters to the total discrepancy. It was also concluded that none of these parameters alone can be responsible for the observed discre- pancies. 8. CONCLUSIONS The technique employing SF, for tracing the stack gases of Reading D power plant (about 500 MW) over the greater Tel-Aviv area enabled us to gain information on the contribution of the power plant to the overall SO. concentrations in the Tel Aviv area. It was found (experiment TA3) that when the wind direction was 238°-244° , the S0_ measured at monitoring stations on the 241°-243° azimuth f.o Reading D originates only from the Reading D power plant. Good agreement between measured SO- concentration, and that calculated according to SFfi concentration was found at distances up to 3.9 km. At 5.75 km from the stack, the measured SO- concentration was lower than that calculated from SF- , thus probably indicating disappear- ance of S02 originating from Reading D. On the other hand, when the wind direction was 305° and 320° (experiments TA2 and TA4, respectively) high S0_ concentrations, which were contributed completely by sources other than Reading D power plant were found at station 75 (experiment TA2) and stations 78 and 80 (experiment TA4). - 29 - fhua the contribution of source (s) other than Reading IJ was proved for these stations under the conditions of the above mentioned experi- ments. An additional conclusion arrived at was that the locations of the SO monitoring stations in the Tel Aviv area do not coincide with the highest wind frequency during the summer. As a result, the plume of Reading D effluents passes over the monitoring stations for rela- tively short periods of time during the day. Thus, the daily average SO. concentrations at other locations which lie on the highest fre- quency wind direction are probably significantly higher than those measured at the present locations. The disappearance of S0~ could be clearly shown only during experiment TA3 anc1 at a distance of 5.75 km from the stack. The measured SOj concentration was lower by a factor of 1.3-1.5 than the concentration calculated from SF,. In order to gain more infor- mation on the disappearance and its rr The use of mobile S0? measuring stations may be required. The comparison of measured and expected SF,- concentrations showed that the measured concentrations were higher (by a factor of 2-4 in most cases) than the calculated concentrations. The Gaussian dispersion model with the constraint of the plume being trapped by a stable layer aloft and therefore affected by multiple reflections, was used for calculating the expected concentration. An analysis of the influence of different parameters entering into the calculation of the expected concentrations was performed. Inaccuracies in wind direction and speed, effective plume height, estimation of stability conditions, estimation of height of the base of the upper inversion layer were considered. It was concluded, that it is impossible to attribute the discrepancy between measured and expected SF, concen- tration to any of the above parameters alone. Additional experiments are needed to confirm the model with more attention given to the above mentioned parameters in order to assess their influence. - y\ - To summarize, the SF^ tracing technique, aseu on very sensi- tive selecti n ot cite tracer in air, can be used for the identifi- acion .ind determination of the contribution of an individual air >jllutH'n source, the assessment of existing dispersion models and data, •leilictii'n ot dispersion under unusu;il source and/or meteorological conditions and finally tiiC assessment ot the pollutant disappearance Mtf. ACKNOWLEDGEMENT Ihe collaboration of the Israel Electric Corp. Ltd. throughout this studv is acknowledged. Thp contributions of J. Gat, S. Dzincharski and A. Elias were instrumental in successfully performing this work. Thanks are clue to ;:. Press for taking charge of the organiza- tional and logistics aspects of the study. Thanks are given to V. '." ec1 ik for assistance in data processing and to G. Singer and :.'. Len Ari of the Meteorological Service at Beit Dagan who performed the meteorological measurements. The following persons collaborated on sampling during the experiments and the authors are grateful for their very valuable assistance: M. Doron, Ben-Zion Cohen, G. Siegelboim, Z. Clit, 1. Frenkel and E. Hakim. - 3! APPENDIX The calculations of S0_ concentrations from SF, measurements / b were made as shown below. The conditions of experiment TA1 are considered. The flow rate of SF, into the stack was: D i SF, m3 SF, 31.6 ——- = 1.896 • 6 min uh The staek gas flow rate was (see Table 2): ~ = 1.088xl06 m a,t 23 C h h Accordingly, the SF, concentration in the stack gas was: 1.896 m3 SF,/h , m3 SF, 6 174xl0"6 6 1.088x10 m stack gas/h m stack gas Suppose that at a certain point the concentration of SF was found to be 1x10 cm SF./cm air. The dilution of stack gases o from the stack to this point was therefore: 10 3 3 IXIO" cm SF./cm air ^3 stack -6 3 3 - ^ 1.74x10 cm SF,/cm stack gas cm air This is the dilution of S0_ neglecting, of course, the disappearance of S02. The emission concentration of SO was (see Table 2): 6 3 4.343xlO yg SO2/Nm stack gas = 3.98x10 yg S02/m stack gas at 25°C Sims the SO., concentration at our point of interest is computed to be: 3.^SxlO ug SiV'm stack gas at 25UC) x 5.75xlO~ (m stack gas/m air) ° = :J9 ..g SO., 'm3 air It can be concluded that a concentration of 1x10 cm SF,/cm air, during experiment TAl, is equivalent to a concentration of 3 229 Mg SO2/m air. - 33 - REFERENCES 1. SLADE, D.H., editor, Meteorology and Atomic Energy 1968, TID-24190, U.S.A.E.C, 1968. 2. SPOMER, L.A., Atmos. Environ. ]_, 353 (1973) 3. N1EMEYER, L.E. and McCORMIC, R.A., J. Air. Pollut. Contr. Ass. J_8, 403 (1968) 4. NICKOLA, P.W., LUDW1CK, J.D. and RAMSDELL, J.V., Isotop. Radiat. Technol. % 65 (1971) 5. BARRY, P.J., Use of argon-41 to study the dispersion of stack effluents, Proc. Nuclear Techniques in Environmental Pollution, I.A.E.A., Vienna, 1971, a. 241. 6. SALTZMAN, B.E., COLEMAN, A.I. and CLEMONS, C.A., Anal. Chem. 38, 753 (1966) 7. COLLINS, G.F., BARTLETT, F.E., TURK, A., EDMONDS, S.M. and MARK, H.L., J. Air Pollut. Contr. Ass. 15_, 109 (1965) 8. TURK, A., EDMONDS, S.M. , MARK, H.L. and COLLINS, G.F., Environ. Sci. Teciuiol. 1, 44 (1968) 9. CLEMONS, C.A., COLEMAN, A.I. and SALTZMAN, B.E., Environ. Sci. Technol. 2_, 551 (1968) 10. HAWKINS, H.F., KURFIS, K.R., LEWIS, B.M. and OSTLUND, H.E., J. Appl. Met. U_, 221 (1972) 11. DIETZ, R.N. and COTE, E.A., Environ. Sci. Technol. ]_, 338 (1973) 12. DRIVAS, P.J. and SHAIR, F.H., Atmos. Environ. 8., 475 (1974) 13. DRIVAS, P.J. and SHAIR, F.H., Atmos. Environ. 8_, 1155 (1974) 14. ASHTON, J.T., DAWE, R.A., MILLER, K.W., SMITH, E.B. and SriCKINGS, B.J., J. Chem. Soc. A1968, 1793 (1968) 15. SIMMONDS, P.G., SHOEMAKE, G.R., LOVELOCK, J.E. and LORD, H.C., Anal. Chem. 44, 860 (1972) 16. GILATH, CH., Int. J. Appl. Radiat. Isotop. _22_, 671 (1371) 17. GILATH, CH., BLIT, S., YOSHPE-PURER, Y. and SHUVAL, H.I., Radioisotope tracer techniques in the investigation of dispersion of sewage and disappearance rate of enteric organisms in coastal • waters, Proc. Nuclear Techniques in Environmental Pollution, IAEA, Vienna, 1971, p. 689. IS. TURNER, D.B., Workbook oi atmospheric dispersion estimates, U.S. Department o£ Health, Education and Welfare, 1969, 19. TURNER, D.B., Estimation of plume rise. Dispersion estimate suggestion., No. 1, A publication of Model Application Branch, NOAA, Triangle Research Park, N. Carolina, 1972. - 35 - TAUI.K 1 Measuring stations for S0? and SF concentration determination Station * Distance from Azimuth to Remarks No. Station name Reading D Reading D (m) 71 Ramat-Aviv 2050 241° Residential 72 Tel-Baruch 3900 243° Residential 73 Ramat-HaSharon 5750 242° Rural 45 7100 242° Residential 4b 10800 237° Rural 41 5750 232° Rural 42 5750 237° Rural 43 5750 247° Residential 44 5750 253° Residential 20 3250 270° Rural 21 5400 269° Rural 74 Bavli 2200 290° Residential 22 3600 290° Residential 75 Bnei-Brsk 5770 290° Densely populated residential and industrial 24 6750 291° Residential 25 3720 306° Densely populated residential 23 5100 308° Residential 26 7100 308° Residential 27 5090 317° Densely populated residential 28 5250 319° ' Residential 77 Nahalat Yitzhak 3450 328° Residential and industrial 78 Kfar Shalem 6510 335° Residential 79 Hakirya 3900 352° Densely populated residential 80 Hatikva 6400 350° Residential SO2 monitoring stations of the Israel Electric Corp. All the unnamed stations were temporary and for SF, measuremants only. TABLE 2 power •t-atloQi operattm data during Sf, injection Experlncnt Ho. IA1 TA3 IA4 Data 27.6.74 15.7.74 30.7.74 8.9.74 Injectiae tlaa 15:30-16:45 16:45-18:00 11:30-12:45 12:20-13:00 Unit D4 81 and B2 Total D4 Bl and B2 Tocal 04 Bl «Dd B2 Total D3 D4 11 and E2 Total Load, KM 192.8 93.46 286.26 201 97 298 199 98.5 297.5 216.3 174.3 94.5 415.1 Fuel, couuapcion. ton/h 44.2 25.7 69.9 46.5 26.6 73.1 46.1 27.0 73.1 49.7 40. B 26.2 ne.7 Stack gaa taapexatuxa, °C 154 177 163 153 185 165.6 155 187 167.5 153 155 1B8 If 2 Spec. VKC. of acack faa, at 273'K kg/tto3 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 1.31 3 at actual T tg/« 0.837 0.794 0.820 0.839 0.780 0.815 0.835 0.776 0.611 0.839 0.835 0.776 0.B21 Stack g» flow rate, 3 3 3 3 3 3 3 ttatyh 595.8xl03 4Oi.5xlO3 997.3xlO3 6l7.7xl03 4O1.5xlO3 1019.2xlO3 6U.6xl0 396.1xl0 1007.8xl0 665.UJ0 562.3X1O 3»9.7*1O 1*1/. ULO 3 3 3 3 3 kg/h 780.SX103 526xl03 1306.5xlO3 809.3x103 526llO3 1335.3xl03 801.3X1O3 518.9X103 1320.3xlO 871.3xlO 736.6X1O 51O.5xIO JH8.4.1D 1 3 3 3 3 3 :! B3/h 932.5xl03 66I.4xlO3 1519.3X103 964.6xl03 674.3xlO3 16381103 959.6I10- 666.9I10 I63OxlO JO38.5xlO M2.1X10 65J.8xlO 25SOllO 7.22 S02 taaeCttl**. Con/h 2.74 1.593 4.33 2.88 1.64 4.52 2.85 1.67 4.52 3.08 2.S2 1.63 SOj cone. In stack faaaa. 4594 3969 4343 4669 4104 4466 4669 4225 4494 4631 4*97 4165 4472 pp«Cw>lu«a) 1606 1387 1518 1632 1435 1561 1632 1*77 1571 1619 1572 1456 1563 ,.. . Supplied by th« Jaraal Elactrlc Carp. Ltd., Eavtraauiitia & Efficiency Coacrol Mpartant TABLE 3 General weather conditions during experiments i Observations at Sde-Dov Daily Temp.(C°) Experiment Time Pressure Temperature Relative Cloudiness Maximum Minimum (mb) (C°) humidity (%) TA1 14:00 1007.3 26.4 67.0 0 27.5 22.4 TA2 15:00 1005.9 28.4 72.0 0 29.2 21.8 TA3 15:00 1005.2 28.8 69.0 2/8 28.8 22.3 TA4 14:00 1008.5 28.4 62.0 0 29.2 19.2 - 38 - TABLE 4 Wind speed and direction: Experiment TA1 Time 15:40 16:13 16:32 Wind Wind Wind Height Speed Direction Speed Direction Speed Direction (m) (m/sec] (m/sec) (m/sec) i 120 4.6 278° 5.2 286° 4.3 277° i 230 5.2 276° 4.5 272° 4.6 288° 335 3.4 291° 4.8 263° 3.3 268° 435 4.3 271° 3.6 255° 4.0 261° 535 4.8 255° 4.7 262° 5.3 267° 635 4.9 262° 5.7 269° 4.5 267° : 735 6.0 259° 4.9 261° 3.7 265° i 835 6.1 263° 4.0 259° 3.1 262° 935 5.4 256° 3.2 267° 2.9 267° 1035 3.3 274° 2.8 276° 1.7 261° TABLE 5 Wind speed and direction: Experiment TA2 Time 17:00 17:30 18:00 Wind Wind Wind Height Speed Direction Speed Direction Speed Direction (m) (m/sec) (m/eec) (m/sec) 120 4.4 306° 4.7 299° 3.8 303° 240 5.4 306° 4.1 304° 4.3 301° 350 4.6 305° 4.5 309° 4.0 309° 460 3.4 322° 4.1 329° 4.7 328° 570 5.0 333° 5.7 325° 6.0 331° 670 6.3 332° 6.8 327° 7.4 327° 870 12.0 328° 13.1 324° 13.7 324° 1070 14.7 318° 12.8 323° 12.6 321° - 39 - TABLE 6 Wind speed and direction: Experiment TA3 i Time I1:20 11:50 12:20 Wind Wind Wind ' Height Speed Direction Speed Direction Speed 1 Direction : On) (m/sec) (m/sec) (m/sec). 120 7.3 249° 6.7 241° 6.9 . 237° 230 6.0 242° 5.6 248° 6.6 1 241C 330 3.7 234° 4.4 244° 6.3 ! 239c 430 3.2 240° 4.6 244° 5.5 ' 234° 530 2.8 213° - - 3.1 i 219° 630 2.5 190° 4.7 204° 4.2 | 220° 730 1.6 200° - _ i 830 2.5 303° — — 1 1 TABLE 7 Wind speed and direction: Experiment TA4 Time 12:30 13:00 13:30 Wind Wind Wind Height Speed Direction Speed Direction Speed Direction Cm) (m/sec) (m/sec) (m/sec) 120 2 325° 4.1 320° 7.2 320° 230 1.5 320° 4.1 320° 6.7 320° 335 1.5 320° 2.0 320° 5.7 320° 435 1.5 320° 2.0 320° 5.1 320° 535 1.5 325° - - 3 300° 635 — — 2.0 320° 4 290° TABLE 8 Atmospheric stability conditions and heights of the base of the stable layer Pasqulll's Height of base stability Expt. Surface wind Global radiation Temp, gradient of stable layer category (m/sec) (cal/cm2 h) (°C/100m) On) * TA1 4 50 -1.7 400 C TA2 4 31 -0.9 400 c: * TA3 7 83 -1.6 500 c o TA4 4.5 73 -1.4 500 c I Stability may be intermediate, between C and B. - 41 - lABLh 9 —————————Concentrations oi— SF,j and So.^, Experiment: TAl SF, concentration Cone. SO calc. Cone. S0« meas. Station Sampling time 2 No. (cm /cm ) (ug/m ) (ug/m ) * 20 15:44-16:1/. 3.5xlCf10 801 _ 16:14-16:44 2.4xlO-10 .550 - -1? 16:44-17:14 5x10 " • 11 - * 21 15:50-16:20 2.2xlO~10 504 - 16:20-16:50 l.SxlO"10 412 - 16:50-17:20 1.7xl0~U 39 - 71 15:38-16:08 5xl0"12 11 20 16:09-16:39 <5xlO"12 <11 30 16:40-17:10 - - 25 72 15:46-16:16 <5xl0"12 <11 20 16:16-16:46 <5xl0~12 <11 20 16:46-17:16 <5xlO"12 <11 20 73 15:54-16:24 <5xlO~12 <11 20 16:24-16:54 <5xl0"12 <11 16 16:54-17:24 <5xl0~12 <11 13 22* 15:46-16:16 - - - 16:18-16:48 1.2xl0~U 28 - 16:49-17:19 3.3xlO~U 76 - 75 15:30-16:00 <5xlO~12 <11 20 16:00-16:30 <5xl0"12 <11 28 16:30-17:00 6xl0~12 14 48 No SO. measurements are available at these stations. - 42 - TABLE 10 Concentrations of SF and SO,, : Experiment TA2 SF^ concentration Cone. S0 calc. Cone. SO2 meas. Station Sampling time 2 / 3. 3, No. (cm /cm ) (ug/m ) (ug/m ) 25 16:59-17:29 1.35X10-10 324 17:29-17:59 1.13X10"10 271 * 23 17:02-17:32 2.9X10"10 696 17:32-18:02 2.7xlO-10 648 * 26 17:09-17:39 2.08xl0"10 499 - 17:39-18:09 2.5xlO-10 600 74 16:52-17:22 8.8xlO~12 21 35 17:22-17:52 <5xlO~12 <12 25 * 22 16:59-17:29 <5xl0~12 <12 17:30-18:00 5xl0-12 12 _ 75 17:05-17:35 <5xl0~12 <12 200 17:35-18:05 <5xl0"12 <12 100 24 17:09-17:39 7.7xl0"12 18 - 17:39-18:09 <5xlO~12 <12 77 16:55-17:25 <5xl0-12 <12 30 17:25-17:55 <5xlO-12 <12 30 78 17:05-17:35 <5xl0~12 <12 15 17:36-18:06 <5xlO-12 <12 20 No SO, measurements are available at these stations. - 43 - TABLE 11 Concentrations of SF, and S0_ : Experiment TA3 ^— D ——— 2. SF, concentration Cone. S0_ calc. Cone. S0_ meas. Station Sampling time 6 , 3, 3, No. (cm /cm ) (ug/m ) (•ug/m ) 71 11:38-12:08 1.25xl0"U 30 35 12:08-12:38 <5xl0"12 <12 25 72 11:46-12:16 2.14X10-10 511 500 12:16-12:46 1.54xlO"10 368 350 73 11:55-12:25 2.1XKT10 502 340 12:25-12:55 1.32xl0-10 315 240 45* 11:58-12:28 1.72xl0-10 411 _ 12:28-12:58 1.17X1O"10 280 - 46* 12:12-12:42 1.19xlO"10 284 _ 12:42-13:12 4.7xlO~U 113 - 41* 11:55-12:25 4.17xlO"U 100 - 12:25-12:55 2.1xl0"U 50 - * 42 11:55-12:25 1.75X10"10 418 - 12:25-12:55 1.15xl0-10 275 - 43* 11:55-12:25 3.34xl0~U 80 - 12:25-12:55 7.28xl0~1L 175 44* 11:55-12:25 1.02X10"11 24 - 12:25-12:55 3.72xl0"L1 89 - No SO, measurements are available at these stations. TABLE 12 Concentrations of SF, and SO., : Experiment TA4 ——————————~— O ——— £ n SF, concentration Cone. SO. calc. Cone. S02 meas. Station Sampling time 6 , 3. 3, No. (cm /cm ) (ug/m ) (Ug/m ) 25* 12:50-13:20 «-5xlO~12 <19 13:20-13:50 •-5xlO~12 23* 13:00-13:30 <5xl0~12 <-19 - 13:30-14:00 3.2xl0~U 122 - * 26 13:15-13:45 5xl0-12 19 - 13:45-14:15 3.1xl0~U 118 - * 27 13:00-13:30 2.65xl0"10 1010 _ 13:30-14:00 2.38xlO"10 907 - * 28 13:00-13:30 3.04xl0~10 1158 _ 10 13:30-14:00 3.7X1O^ 1410 - 77 12:50-13:20 6.45xl0~U 246 310 13:20-13:50 1.27xl0~U 48 170 78 13:12-13:42 <5xl0"12 <19 360 13:42-14:12 <5xlO~12 <19 210 79 12:52-13:22 <5xl0-12 <19 35 13:23-13:53 <5xlO"12 <19 25 80 13:12-13:42 <5xl0~12 <19 228 13:42-14:12 <5xl0~12 <19 104 No S0_ measurements are available at these stations. tcd_ and calculated Sf. concent rations: £xpprliscnc TAl j h b Station Samp Hag tlraa Wind" y a XCU,0,0) xdU.y.O) c I lEO*sured *10 «10.,'«.y.'.j No. y 3 Co) Co) Cm) Im) Ug/m ) (M&/O3) C-g/o3) (.g'n3! 20 15:44-16:14 U2 3250 0 J10 180 0.69 0.69 2.135 2.56 3.7 16:14-16:44 W3 3250 228 310 ieo 0.74 0.56 1.46 1.76 j 3.1 21 15i50-16:20 W2 5400 95 460 285 1.29 1.26 1.34 1.61 1.3 16:20-16:50 U3 5400 470 460 265 1.40 0.83 1.10 1.32 1.6 71 15:38-16:08 Ml 1640 1230 165 98 7.OxlO~3 6.2xl0"lS 0.031 0.037 6.0xl0U 16:09-16:39 W2 1780 1040 180 105 1.7xlO"2 ?.5*10-10 <0.031 72 15:46-16:L6 W2 3470 1770 330 195 0.86 5.0K10~7 <0.031 73 15=54-16:24 U2 5060 2700 450 290 1.33 2.0il0"6 22 16:18-16:48 U3 3460 990 320 190 0.86 0.007 0.073 0.0B8 12 75 15:3O-16s00 Wl 5650 1200 330 300 1.93 7.5xlO"3 <0.03J Hole: The effecttv* plume height and the upper inversion base were 400 m. a) Wind speed and direction Wl: 4.4 m/sec, 278° at 15:40 H2: 4.5 D/BBC, 270° at 16:13 U3: 4.2 m/8ec, 274' at 16:32 b) Paaquill stability condition C c) xix.,0,0) i« the calculated canterline ground level concentration b c ' ' 1 Station Sampling date Wind* X y o x U,o,o) d * U.y.i« *Maau»d. 25 16:59-17:29 Wl 3720 65 350 200 0.85 0.83 0.82 1.00 1.2 17:29-17:59 Mi 3720 130 350 200 0.93 0.87 0.69 0.83 0.95 23 17:02-17:32 Wl 5100 270 460 270 1.19 1.00 1.77 2.12 2.1 17:32-18:02 W2 5100 360 460 270 l.il 0.97 1.65 1.98 2 26 17:09-17:39 Wl 7100 37U 620 370 1.08 0.66 1.27 l.SZ . 2.3 17:39-15:09 U2 7100 500 620 3?0 1.19 0.4B 1.52 1.B3 3.8 7* 16:52-17:22 Wl 7125 570 210 120 0.069 0.0017 0.054 0.064 37.6 17:22-17:52 W2 2135 530 210 120 0.075 0.003 <0.03 <0.036 22 16:59-17:29 Wl 3480 930 330 190 0.78 0.015 vQ.03 <0.036 17:30-18:00 W2 3490 870 330 190 0.85 0.025 0.03 0.036 1.4 75 17:05-17:35 Wl 5570 1490 500 295 1.19 0.014 <0.03 '0,035 - 17:35-13:05 H2 5600 1400 500 295 1.30 0.026 <0.03 <0.036 24 17:09-17:39 HI 6550 1630 380 340 0.86 8.7xlO~5 0.047 0.056 6.4xlOZ 17:39-18:09 W2 6550 1520 380 340 0.94 3.21U0-4 <0.03 <0.036 77 16,-55-17:25 Wl 3175 1345 300 175 0.61 2.67xlO"5 <0.03 <0.036 17:25-17:55 W2 3155 1405 300 175 0.67 1.17xl0~5 <0.03 <0.036 78 17:05-17:35 Wl 5640 3255 500 295 1.19 7.5X1O-10 <0.03 <0.036 17:36-18:06 W2 5580 3350 500 295 1.30 2.3X10"10 <0.03 '0.036 - Note: Thii upper lavarsion base uaa at 400 m. a) Wind speed and direction and effective plume halj.it for: Wl: 4.6 a/sec, 305° , H - 400 m at 17:00 W2; 4.2 Wsec, 304° , H - 400 m at 17:30 b) Pasqulll stability condition C c) x(*i0.0) ti tha calculated centerlino ground level concentration d) xCx,y1O) ts the calculated ground level concentration ) Xtn the measured concentration of SF, corrected for a 10 minute sampling period 0 Measure— ———*—————-•-d and calculated —SF {.] concontr.it.lun• a• . i Experiment t TA3 b b Station Sampling cine Wind" , X Xj />.(x.y,O) No. *neaaureii 10 o Cm) <»} (») , <») (Pg/a3) Cug/n3) 71 lit 38-12:08 Wl 2050 107 200 120 0.007 0.006 0.076 0.091 15 U: 08-12138 vz 2050 107 200 120 0,053 0.0046 <0.030 ••0.037 72 11:46-12:16 Wl 3900 68 360 310 0.33 0.32 1.3 1.56 4.9 12:16-12:46 W2 3900 340 360 210 0.38 0.25 0.94 1.13 4.5 73 11:53-12;25 Wl 5750 200 510 300 0.66 0.61 1.28 1.53 2.5 12:25-12:55 W2 5750 400 510 300 0.61 0.45 0.80 0.96 :>..l 45 11:58-12:28 Wl 7100 248 620 370 0.68 0.63 1.05 1.26 2 12:28-22:58 W2 7100 496 620 370 0.58 0.42 0.71 0.85 2 46 12112-12i42 Wl 1P800 1316 900 5&Q 0.54 0.18 0.73 0.87 4.8 12:42-13:12 W2 loaoo 189 900 54fr 0,46 0.45 0.29 0.35 0.8 41 11:55-12:25 Wl 5750 1200 510 300 0.66 0.041 0.25 0.30 7.3 12:25-12:55 wz 5750 600 510 300 0.61 0.30 0.13 0.16 0.5 42 11:55-12:25 Wl 5750 700 510 300 0.66 0.26 i.or 1.28 5 12:25-12:55 U2 5750 100 510 300 0.61 0.60 0.70 0.84 1.4 43 11:55-12:25 Wl 5750 300 51Q 300 0.66 0.55 0.20 0.24 0.44 12:25-12:55 W2 5750 900 510 300 0.61 0.13 0.44 0.53 4 44 11:55-12:25 Wl 5750 800 510 300 0.66 0.19 0.062 0.074 0.4 12:25-12:55 W2 5750 1400 510 300 0.61 0.014 0.21 0.25 18 Note: The upper Inversion base was aft 500 m a) Wind speed and direction and effective plume height for: Wl! S.3 m/see, 244* , H - 450 m at 11:50 W2: 6.3 m/see, 238° , H - 400 m at 12:20 b) Pasquill stability condition C c) xCx.0,0) la the calculated centerline ground level concentration d) x(*iy»°) iB th« calculated ground level concentration period e) x fl i« thft measured concentration of SFf corrected for a 10 minute sampling TA&LE 16 ami caiautafJ SF, concentration*: Exp«rl—m TA4 Station { Sapling clu Wind* * X x X /)i{s,y 0> Ka, I •/ MMure 25 11:50-13:20 Wl 3600 900 330 JQO 0.45 o.ou 23 13:00-13:30 Wl 4990 1060 450 270 1.01 0.062 <0.03 *O.0J7 13:30-14:00 W2 4990 two 450 270 0.49 0.030 0.19 0.23 7,6 26 13:15-15:45 Wl 6940 1477 600 360 1.20 0.038 0.03 0,037 • 0.6 13:43-14:» « 6940 1477 600 360 0.58 0.028 0,189 0,227 8.1 27 13:00-l3t3Q Ml 5090 268 460 270 0.99 0.84 1,62 1.94 1.3 13:30-14i00 W2 5090 268 460 270 0.48 0.41 1.45 1.74 4,2 28 13:00-13:30 Wl 5220 92 440 26Q 0.94 0.92 1.83 2,20 2.4 13:30-14:00 W2 5250 92 440 260 0.43 0.44 2.26 2.71 6.2 77 12:30-13:20 Wl 3415 480 320 190 0.35 •o.u 0.39 0.47 4,3 13:20-13:50 K2 3415 480 320 190 0.17 0.055 0.077 0.093 1.7 78 13:12-13:42 Wl 6290 1685 560 390 0.78 0.0086 <0.03 <0.037 • 13:42-14:12 uz 6290 1685 560 390 0.38 0.0042 <0.03 <0.037 79 U:52-13:22 3310 2067 300 1B0 0.26 1.28xlO~U <0.03 \ 80 13:12-13:42 Wl 5340 3200 490 290 1.09 6.0.10-10 <0.03 <0.037 10 13:42-14:12 5S40 3200 490 290 0.53 2.9X1O" <0.03 <0.037 - Noee: The effective pluna height and the upper invereion baae vere 500 m a) Wind apead and direction for: Wl: 3 m/aec, 320* at 13:00 H2i 6.2 a/ae«, 320' at 13:30 b) Paaq>lll •cablllty condition C o) x(*.0.0) !• the calculated canterllne ground level concentration d) X(*.yfO) !• the calculated ground level concentration 1 B e) XIQ the naaaitced concentration of SPfi corrected for • 10 minute aaapllng period - 49 - N £000 m 9Mlt Fig. 1 Map of the SO, monitoring and SF, measuring stations in the Tel-Aviv area C - Reading power station C 0 - Reading power station D • -,;.;.:•>•'•» - 50 - I I 1 15 20 25 30 10 15 20 25 lomp. (t) Fig. 2 Temperature profile as measured at Beit Dagan. Experiment TA1 Adiab^ic temperature profile (lapse rate) 1 1 1 1 1500- " \ 19" \ \ \ \ \ \ \ - 1000 \ - \ \ \ 1t \ - 500- - - 1 1 15 20 25 30 15 20 25 30 Temp.Cfc) Fig. 3 Temperature profile as measured at Beit Dagan. Experiment TA2 Adiabatic temperature profile (lapse rate) - 51 - 1500- 1000- 500- 20 25 30 15 20 25 30 Temp. ("C) Fig. 4 Temperature profile as measured at Beit Dagan. Experiment TA3 ' Adiabatic temperature profile (lapse rate) i i i i (SCO- "2 1000 - Fig. 5 Temperature profile as measured at Beit Dagan. Experiment TA4 Adiabatic temperature 500- profile (lapse rate) 15 20 25 30 35 Temp. (X) - 52 - 1000- Wind Speed (m/sec) Fig. 6 Wind profile at Reading 0. Speed and direction. Experiment TA1 • West wind blowing toward the point 1000 500 6 9 3 6 9 12 3 Wind Speed (m/sec) Fig* 1 _ _ _;., Wind profile at Reading D. Speed and direction. Experiment TA2 ——• West wind blowing toward the point - 53 - 1 1 1 1 lisa |2fifi -= 500- \" - " I • ^ s. 1 3 6 0 3 6 0 3 6 Wind Speed (m/sec) Fig. 8 Wind profile at Reading D. Speed and direction. Experiment TA3 • West wind blowing toward the point 800 400 0 4 0 Wind Speed (m/sec) Fig. 9 Wind profile at Reading D. Speed and direction. Experiment TA4 ——• West wind blowing toward the point Station No. 600 41 42 73 43 44 600 1 1 1 I i r \ Oys 500 m 400 - 200 I If If i v1 n -1000 -S00 O 500 1000 3 6 9 12 Distance from station No.73(m) Distance from Reading 0 (km) Fig. 10 Fig. 11 S02 concentrations calculated from SFg measurements, Ground level S02 concentrations measured and computed on a line perpendicular to the plume axis, at a from SFg measurements, as a function of distance distance of 5750 m from the source. Experiment TA3 from Reading D- Experiment TA3 • first sampling period * First sampling period, calculated SO2 cotic. A second sampling period Second sampling period, calculated SO^ cone. o Measured SO2 concentration, first period • Measured SO2 concentration, second period