Embed Size (px)
Citation preview
FIELD STUDIES OF THE PLUMEFROM THE MOHAVE COAL-FIRED
POWER PLANT
by
Dean A. Hegg and Peter V. HobbsCloud and Aerosol Research Group
University of WashingtonSeattle, Washington 98195
ANNUAL REPORT FOR 1983 TO SOUTHERN CALIFORNIAEDISON COMPANY FOR P.O. NUMBER B2618901
AUGUST 1984
SUMMARY
Data col lected over a three-year period in the plume from the Mohave coal-fired
power plant have been analyzed and have yielded the following information:
The Mohave plume general ly has little vertical extent even at rather
large downwi nd di stances. The ratio of the wi dth of the pl ume to its
height is commonly 40:1 or greater in summer. More limited data taken
during the winter reveals a ratio of width-to-height of less than 20: 1.
The NO-to-NO? conversion rate in the plume is di ffusion limited.
Li ght absorption due to particles in the Mohave plume does not differ
significantly from that due to particles in the surrounding ambient
ai r.
While sul fate and nitrate occasional ly make substantial contri butions
to the total particulate volume in the Mohave pl ume, the contri bution
of each species is generally less than 10%, with that of nitrate
substantial ly less than that of sulfate.
The sul fate and total particle mass di stributions in the plume are
simil ar, with both distributions general ly peaking in the sub-mi cron
size range. That is, the percentage contribution of sulfate to the
total particle mass in the plume remains essentially constant for al
particle sizes.
The gas-to-parti cle conversion rates of sul fate and nitrate are low in
the Mohave plume, with respective mean rates of ~0. 7 and ~0.1 % h
Dry deposition appears to be the major sink for SO? n the Mohave
plume.
SUMMARY (Continued)
The above ambient value of the light-scattering coefficient (bs catand sul fate volume in the plume are not wel correlated, the above
ambient val ues of b and the total volume of sub-micron particless cac
do correlate wel This illustrates the importance of primary par-
ticles from the plant in determining ight scattering in the Mohave
Pl ume.
Light scattering by particles and NO,, absorption contribute about
equal ly to the opti cal depth of the Mohave Plume.
n
TABLE OF CONTENTS
Page No.
-A SECTION 1 1
INTRODUCTION 1
SECTION 2 3
LOCATION OF THE FIELD STUDIES AND THE NATURE OF THE MOHAVE PLANT 3
SECTION 3 5
INSTRUMENTATION AND DESIGN OF THE FIELD STUDIES 5
3.1 Instrumentation 5
3.2 Sampl ing Procedures 15
SECTION 4 18
RESULTS OF THE FIELD STUDIES 18
4. 1 The Data Base 18
4.2 Trace Gases and Light Scattering Coefficients 18
4.3 Si ze Distri bution of Particles 25
4.4 Fi lter Data 26
4.5 Impactor Data 31
4.6 Telephotometer Data 33
4. 7 Plant Loadings 40
SECTION 5 42
ANALYSIS OF THE FIELD DATA 42
5.1 Geometry of the Plume 42
5.2 NO-to-NO^ Conversion 69
5.3 Light Absorption by Particles in the Plume 72
<1 5.4 Particle Size Di stributions in the Plume 73-s
5.5 Sulfate and Nitrate in the Plume 79t
5.6 Trace Constituents in the Plume 98
TABLE OF CONTENTS (Continued)
Page No.
SECTION 6 102
ANALYSIS OF THE FIELD DATA REGARDING VISUAL IMPACT OF THE PLUME 102
6.1 Relationship Between b and SO" in the Plume 102S CBL
6.2 Relationship Between b and Total Particulate Volume ins CBL
the Plume 102
6.3 Optical Depths from In-Situ Measurements 110
6.4 Comparison of Optical Depths of the Plume Derived from In-Situ
Measurements and Measured with a Telephotometer 114
ACKNOWLEDGMENTS 118
REFERENCES 119
APPENDIX A: CROSS SECTIONS OF THE MOHAVE PLUME IN THE X-Z PLANE 121
.APPENDIX B: SOg CONCENTRATIONS IN THE Y-Z PLANE OF THE MOHAVE PLUME 142
APPENDIX C: ABOVE AMBIENT CONCENTRATIONS OF 0.55 urn DIAMETER 157PARTICLES IN THE X-Z PLANE OF THE MOHAVE PLUME
APPENDIX D: TOTAL CONCENTRATIONS OF PARTICLES IN THE Y-Z 163PLANE OF THE MOHAVE PLUME
APPENDIX E: PARTICLE SIZE DISTRIBUTIONS IN THE MOHAVE PLUME 171
V
FIELD STUDIES OF THE PLUME FROM THE MOHAVE COAL-FIRED POWER PLANT
SECTION 1
INTRODUCTION
The impact of the emissions from’coal-fired power plants on ai r quality
has received considerable attention during the past decade. Because of the per-
ceived cause-and-effect relationship between particulate sulfate and visibility
degradation (Boli n and Charlson, 1976; Gi lani et at 1981) much of the
research has concentrated on the formation of secondary sul fate and the effects
of this sul fate on visi bil ity. This has been especial ly true of studies con-
ducted in the southwestern United States (Ri chards et a1 1981; Hering et_a1_.
1981; Macias et a1 1981). The background visibi lity in this area is excep-
tional ly good and thus may be particularly sensitive to degradation. However,
recent research has suggested that power pl ants are just one of several sources
that may affect regional visibi lity in the southwestern United States. For
example. Hotter et a1 (1981) have shown that the Los Angeles urban pl ume can
impact this area. Al so, both brushfires and copper smelters can affect visibi-
ity in the southwest (Macias et a1 1981; Hobbs et a1 1982). Even in the
case of power plant plumes, it is not clear that particulate sul fate is always
the major contributor to visibil ity degradation (Ri chards et a1 1981; Hegg and
Hobbs, 1983). Variables such as time of year, meteorological conditions, and
the activities of other pol lutant sources, probably affect both the extent and
nature of any impact on a region of the emissions from various sources.
-2-
To explore the effects of a single power plant on the ambient ai r in the
arid southwestern region of the United States, the Southern Cali fornia Edison
(SCE Company and its contractors are involved in a detai led study of the pl ume
from the Mohave coal power plant. As part of this project, the University of
Washington’ s (UW) Cl oud and Aerosol Research group carried out ai rborne studies
during the wi nter of 1978, the summer of 1979, and the summer of 1980. In this
report we use the ai rborne data col lected in these field studies to expl ore the
geographi cal extent of the Mohave plume, the production rates of sul fate and
nitrate in the plume, NO? production in the plume, particles in the pl ume and
the opti cal depths of the pl ume.
-3-
SECTION 2
LOCATION OF THE FIELD STUDIES AND THE NATURE OF THE MOHAVE PLANT
The Mohave power pl ant is situated at Laughl in, Nevada on the banks of
the Colorado Ri ver. Laughl in is located 150 km south of Las Vegas, Nevada, and
48 km west of Kingman, Arizona. It is about 4 km south of Davis Dam and Lake
Mohave. Several hundred ki lometers to the northeast of the plant are the Grand
Canyon, Zi on and Bryce National Parks (Fi g. 2. 1 ). These parks have been
designated as Cl ass 1 federal areas by the Envi ronmental Protection Agency.
The Colorado Ri ver Val ley is oriented essential ly north-south in the vici-
nity of the Mohave plant. The val ley floor extends roughly 3 km on either side
of the river before rising to a height of 1300 meters MSL. The plant itself is
situated at an altitude of 166 m MSL and its stack ri ses an additional 152
meters. Because of the channel ling effect of the river val ley, and the relati-
vely low height of the Mohave stack, the plume from the Mohave plant commonly
moves along the val ley.
The Mohave pl ant is fueled by coal from the Bl ack Mesa Mine, which is
located near Kayenta, Arizona, about 600 km from the pl ant. The coal is crushed
at the mine and blended with water to form a coal slurry (50% coal by weight)
The sl urry is piped to the plant, centri fuged, pul verized and injected into the
boi lers. The coal has a moisture content of 12%, it is 10% dry ash and has a
sul fur content of 0.5%.
The Mohave plant has two generating units, each equipped with an electrosta-
tic precipitator (manufactured by United Conveyor) that have a rated removal
efficiency for particul ate mass of 98.6%.
-4-
Figure 2.1. The locations of the Mohave power plant and the Grand Canyon, Bryce, and Zion NationalParks (outlined by dashed lines). Cities are represented by squares, small towns by dots, and the GrandCanyon Visitors’ Center (V.C.) by a cross.
-5-
SECTION 3
INSTRUMENTATION AND DESIGN OF THE FIELD STUDIES
3. 1 Instrumentation
Most of the data described in this report were obtained from instrumen-
tation aboard the UW B-23 research ai rcraft. The extensive instrumentation
system aboard this ai rcraft is indi cated in Fi gs. 3.1 and 3.2 and sted in
Table 3.1. The aerosol equipment is capable of measuring particles with di ame-
ters between 0.01 and 60 urn. The trace gas equipment al lows measurements of
total gaseous sul fur, 0.,, NO, NOp and NO Tefl on fi lters analyzed by ion^ J\
exchange chromatography provide the concentrations of parti culate sulfates and
nitrates. A nephelometer provides measurements of particulate light-scattering,
which is a major cause of visi bi ity impai rment. Detai led descriptions of the
instrumentation system, including calibration techniques, have been given by
Hobbs et a1 (1976) Hegg et a1 (1976) and Hegg and Hobbs (1980).
In addition to the data acquisition capabi ities integral to the B-23
ai rcraft, which are isted in Table 3. 1, information on particle composition was
obtained by exposing quartz fi ber fi lters to the ai r; these were subsequently
analyzed for particle absorption by Dr. T. Novakov of the Lawrence-Li vennore
Laboratory.
During the 1980 field study the UW equipped and flew a second ai rcraft (a
Cessna 206) which was employed to acquire additional data and to provide more
flexibi lity to the ai rborne sampl ing program. This ai rcraft was equipped with a
Meloy Model 160 FPD sul fur analyzer that was used to locate the Mohave pl ume.
-6-
INSTRUMENT PODMOUNTED ONFORWARD EDGEOF BELLY
ENGINE EXHAUSTVENTED OUTBOARDBENEATH WING
MOUNTEDBENEATHWING
^SI^V* Research instruments on the UW B-23 research ai rcraft. See pages7 and 8 for key to symbols used in this diagram.
-7-
Key to Fi gure 3.1.
1-2 Pi lot and Co-pi lot3 Meteorological Observer
4 Instrumentation Engineer5 Fl ight Di rector
A 5 cm gyrostabi ized weather radar
B Rosemount ai rspeed, pressure altitude and total temperature probes,MRI-turbul ence probe and electronics, J-W liquid water probe, angle ofattack sensors
C VOR-DME sl aved position plotter; research power panel (3 kW 110V 60 Hz1.6 kW 110V 400 Hz; 150 amps 28V dc) Doppler horizontal winds
D Electronic controls for J-W liquid water indicator, dew point thermometer,time code generator and time displ ay, MWV time standard receiver, TAS andT+Q^ analog computers, signal conditioning ampl ifiers, audio signal mixers-,FSK time-share data multiplexers (63 channels) 2-D electric field andturbulence analog readouts
E Mini computer (16-bit word 16K-word capacity) computer interface toinstrumentation, remote A-D converter, keyboard and printer, floppy disk
F Hybrid analog/digital tape recorder (7-track 1 /2") and high speed 6-channelanalog strip chart recorder
G Inlet for isokinetic aerosol sampl ing
H Ai rcraft oxygen, digital readout of al fl ight parameters, relative humiditysensor, time code reader and time di splay, heated aerosol plenum chamber,verti cal velocity, Mi lipore sequential filter system
I Controls for metal foil impactor, PMS-2D image processor and digitalrecorder
J Aerosol analysis section, general ly contains: integrating nephelometer,mass monitor, diffusion battery, automatic cloud condensation nucleuscounter, Whitby aerosol analyzer, Royco particle counters, automaticcondensation nucleus counter, automatic grab samplers (28 A and 55 A)
K PMS axial ly scattering spectrometer (smal dropl et probe) verticallymounted
(continued)
-8-
Key to Fi gure 3. 1. (Continued)
L Analog fl ight parameters and digital cloud physics data di splay, colorgraphics terminal and PMS 2-D image repeater
M PMS 1-D optical array precipitation and cloud particle spectrometer
N 2-D PMS optical array precipitation and cloud particle image probes
0 Ultraviolet photometer
P Electric field mil sensor (vertical and horizontal fiel d)
Q Automatic ice particle counter
R Metal foil hydrometeor impactor
S Ion conductivity sensor
T Gas analysis system: SO^, 03, NO, NO^, hydrocarbon, NN3U Radar repeater, side-viewing automatic camera, real-time display of 1-D
PMS data
V Radar altimeter, 2-D electric field mil electronics, 8-channel tele-metry transmitter, dew point sensor
W Instrument vacuum system (consists of four high-capacity vacuum pumps,connected individual ly to the cabin)
X Parachutes, survival gear, ife raft
-9-
AUTOMATIC VALVE SEQUENTIALBAG SAMPLER (FOR OPC 8 EAA)-
-CLOUD WATERSAMPLER AITKEN NUCLEUS
COUNTER’
ELECTRICAL AEROSOLANALYZER (EAA) 6MASS MONITOR
INTEGRATINGNEPHELOMETER
ISOKINETICPROBE
STATICPRESSURETRANSDUCER
\-30A HEATEDCHAMBER
ISOKINETICPUMP
PROBE FORMANUAL BAGSAMPLE (UPTO 3 MSCAPACITY)- FORFILTERS, CASCADEIMPACTORS, ETC
GAS ANALYSISSYSTEM (NO.NH,NOz. SOz, AND 03)
OPTICALPARTICLECOUNTERS(OPC i an)
FRONT
INLET FORISOKINETICPROBE
AXIALLYSCATTERINGSPECTROMETERPROBE
openSENSOR
ISOKINETIC PUMP
Figure 3.2 Detai ls on instrumentation aboard the UW B-23 research ai rcraft.
-10-
TABLE 3.1 Specifi cations of Research Instruments Aboardthe UW B-23 Research Ai rcraft.
Parameter
Total ai rtemperature"*"
Static ai rtemperature"*"
Dew point"*"
Pressureattitude1’
True ai rspeed"*"
Ai r turbul ence1’
Instrument type
Plati num wi reresistance
Computer value
Dew condensation
Variablecapacitance
Variablecapacitance
Di fferential
Manufacturer
Rosemount Model102CY2CG + 414 LBridge
In-house
Cambridge SystemsModel TH73-244
RosemountModel 830 BA
RosemountModel 831 BA
MeteorologyResearch, Inc.Model 1120
Range (and error)*
-70 to 30C(+/- 0.1 C)
-70 to 30C(+/- 0.5C)
-40 to 50C(+/- C)
150 to 1060 mb(+/- 0.2%)
0 to 230 m s-1(+/- 0.2%)
0 to 10 cm2/3 s-1(+/- 10%)
Hot wi re resistance Johnson-Wil iamsLiquid watercontent1’
El ectric field1’1’Rotary field mi MeteorologyResearch, Inc.Model 611
MeteorologyResearch, Inc.Model 1220A
In-house
Types and sizes Metal foi impactorof hydro-
Ice particle Optical polarizationconcentrations " technique
* Al particle sizes refer to maximum parti cle dimensions.Data displayed or avai lable aboard the ai rcraft.TT Not relevant to this study.
0 to 2 g m-30 to 6 g m~3
0 to 110 kV m(+/- 10%)
Detects particles(> 250um)
0 to 1000 A-1detects particles(> 50pm)
-11-
TABLE 3. 1 Speci fications of Research Instruments Aboardthe UW B-23 Research Ai rcraft. (Continued)
Parameter Instrument type Manufacturer Range (and error)’
Concentration ofcloud condensa-tion nuclei t
Ice nucleusconcentrations’*" 1"1’
Ice nucleusconcentrations1’ ^Concentrations ofsodium-containingparticles1’ +1’
Altitude aboveterrain1’
Ai rcraftposition andcourse plotter1’
Time1’
Time +
Ground communi-cation1’
Li ght-scatteringcoefficient1’
Li ght-scattering
NCAR acousticalcounter
Polarizing
Fl ame spectrometer
Radar altimeter
Works off DMEand VOR
Time code generator
Radio WWV
FM transceiver
Weather radar1’ t’1’ 5 cm gyro-stabi ized
Integrating nephelo-meter
In-house
In-house
Mee Industries
In-house
AN/APN22
Radio Corp. ofAmerica, AVQ-10
In-house
Systron DonnerModel 8220
Gertsch RHF 1
Motorola
Meteorology Res.Inc. Model 1567(modi fied forincreased stabi ityand better responsetime)
0 to 5000 cm-3(+/- 10%)
0.01 to 500 A-1
0. 1 to 10,000 &-1
0 to 10,000 &-1(+/- 1%)
0 to 6 km(+/- 5%)
100 km
180 km(1 km)
h, min, s(1 105)min
200 km
0 to 2.5 x 10-4 m-or
0 to 10 x 10-4 m-1
1-4 m-1
* Al particle sizes refer- to maximum particle dimensions.Data displayed or avai lable aboard the ai rcraft.
+t Not relevant to this study.
-12-
TABLE 3.1 Speci fi cations of Research Instruments Aboardthe UW B-23 Research Ai rcraft. (Continued)
Parameter
Heading1’
Ground speed anddrift ang1e1’
Ultravioletradiation1’
Angle of attack!"
Photographs1’
Total gaseoussulfur"1
Ozone !’
NO, N02, NO +
Si ze spectrum ofaerosol particles1’
Si ze spectrum ofaerosol particles1’
Si ze spectrum ofaerosol particles1’
Si ze spectrumof aerosolparticles
Instrument type
Gyrocompass
Doppler navigator
Barrier-layerphotoel ectric cel
Potentiometer
35mm time-lapsecamera
FPD flamephotometric detector
Chemiluminescence(C2H4)
Chemi luminescence(03)
Electrical mobi lityanalyzer
90 ight-scattering
Forwardight-scattering
Di ffusion battery
Manufacturer
Sperry Model C-2
Bendix ModelDRA-12
Eppl ey Laboratory,Inc. Model 14042
RosemountModel 861
AutomaxModel GS-2D-111
Meloy Model 285
Monitor LabsModel 8410 A
Monitor LabsModel 8440
Thermal Systems,Inc. Model 3030
Royco 202(in-house modi fied)
Royco 225(in-house modi fied)
Thermal Systems,Inc. Model 3040with in-houseautomatic valves &sequencing
Range (and error)*
0 to 360(+/- 2%)
0 to 6 km altitude
0.7 J m-2 s-1(+/- 5%)
+/- 23(+/- 0.5)
T s to 10 min
0.5 ppb ppm
0 to 5 ppm(+/- 7 ppb)
0 to 5 ppm(+/- 10 ppb)
0.0032 to 1.0 urn
0.3 to 12 urn
1.5 to 40 urn
0.01 0.2 urn
* Al parti cle sizes refer to maximum particle dimensions.+ Data displayed or avai lable aboard the ai rcraft.++ Not relevant to this study.
-13-
TABLE 3. 1 Speci fications of Research Instruments Aboardthe UW B-23 Research Ai rcraft. (Continued)
Parameter Instrument type Manufacturer Range (and error)’
Si ze spectrumaerosol andcl oud particles11
Si ze spectrum Di odecloud parti cles1’1’ occul ation
Si ze spectrum ofprecipitationparticlestt
Concentrationsof Ai tken nuclei 1’
Concentrationsof Aitken nuclei 1’
Si zes and typesof aerosolparticles t"
Concentrations ofce nuclei 1’11
Mass concentrationaerosol particles"*"
Particulate
SO^, NO^", C1 ’,
Na^ K+, NH^Cl oud watersamples1’1’
Forward ight-scattering
Diodeoccul tation
Li ght transmission
Rapid expansion
Di rect impaction
Di rect impaction
Electrostatic depo-sition onto matchedosci lators
Teflon filtersCXI & Dionex XRFspectroscopy andon exchangechromatography
Centri fuge
Cascade impactor
Particle MeasuringSystems ModelASSP100
Particle MeasuringSystems, ModelOAP-200X
Parti cl e MeasuringSystems ModelOAP-200Y
General El ectricModel CNC II
Gardner
Glass sl ides
Nuclepore/Mi H pore
Thermal SystemsInc. Model 3205
In-house
In-house
Sierra InstrumentsInc.
1.5 to 70 pm
20 to 300 pm
300 to 4500 urn
102 to 106 cm-3(parti cles >0.001 um)
2 x 102 to 1Q7 cm
5 to 100 urn
i-30.1 to 3000 ug m(+/- 0. 1 ug m-3)
0.1 to 50 urn m-3(for 500& ai r sample)
Col lects clouddroplets >3 pmradius with anefficiency >20%.
0. 1 3 urn(6 size fractions)
Si ze-segregatedconcentrationsof aerosol particles
* Al particle sizes refer to maximum particle dimensions.+ Data displayed or avai lable aboard the ai rcraft.++ Not relevant to this study.
-14-
TABLE 3.1 Specifications of Research Instruments Aboardthe UM B-23 Research Ai rcraft. (Continued)
Parameter Instrument type Manufacturer Range (and error)
Cl oud watersamples1"1’
A.S.R.C. In-house basedon A.S.R.C. design
Col lects cloud droplets>5 pm with an effi cient>70%
Totalhydrocarbons1"1’
Gas chromatograph Analytical >0.5 ppmInstruments Inc.
H202 (liquidnha<p^ TTphase)
Chemi luminescentreaction withuminol
In-house >10 ppb (Liquid phase)
* Al particle sizes refer to maximum particle dimensions.+ Data di splayed or avai lable aboard the ai rcraft.ft Not relevant to this study.
-15-
The Cessna 206 was also fitted with a bag sampl ing system simi lar to the 500 L
bag sampl er used aboard the B-23. Hi gh-vol ume fi lter samples were taken and
subsequently analyzed for total inorgani c and organic sul fur by Dr. D. Eatough
of Brigham Young University. Low-volume cascade impactor samples were also
acqui red for analysis of the size distribution of sul fur, and several other
trace species by means of PIXE. This analysis was also performed by Dr. D.
Eatough.
Limited measurements made on the ground were used to supplement the ai r-
borne data. The ground-based faci ities included the Spi rit Mountain Research
Station, operated by the Desert Research Institute (DRI and a telephotometer,-
operated by Southern Cal fornia Edison (SCE personnel SCE personnel also
launched pi lot bal loons on several occasions to aid in determining the ai rflow.
3.2. Sampt ing Procedures
The basi c B-23 fl ight pattern that we have used to sample the Mohave plume
is shown in Fi g. 3.3. Samples were fi rst taken within a di stance of about 1 km
from the stack and then the ai rcraft flew at di fferent altitudes in the plume at
various di stances downwind from the stack. Each horizontal traverse was
extended wel out into ambient ai r to al low determination of the background
values for each parameter measured.
A set of plume sampl es normally consisted of continuous measurements
across the width of the pl ume of trace gases, the ight-scattering coefficient
and various meteorological parameters. When the continuous real-time measure-
ments indicated that the center of the pl ume had been reached, a "grab bag"
-15-
Figure 3.3. B-23 research ai rcraft fl ight pattern used for sampl ing the pl
-17-
ai r sampl e was taken for measurements of the parti cle size spectrum. The par-
ticle size spectrum measurements requi red ~2 min, and therefore could not
be carried out i’n real time. However, the grab bag coul d be fi led in ~2 s and
therefore the measurements from the system coul d be used to characterize the
central -100 m of the pl ume on each traverse. The grab-bag sampl es were not fed
into the Royco 225 or the ASSP-100, since these instruments measure large par-
ticles (>1.5 urn in diameter) that are not sampl ed rel iably by the grab bag
technique. When possible, the ai rcraft was flown in an orbit in the plume to
sampl e the large particles in situ. When a quartz fi lter sample, or a sul fate-
nitrate fi lter sample, was desi red, the 500 iter sample bag (see Fig. 3.2) was"fi led as close to the center of the pl ume as possible. Fi ing time was ~4 s.
After the bag was fi led, the sample was passed through one or the other fi lter
types.
The bag sampl ing technique used on the Cessna 206 was simi lar to that for
the B-23, except that only the sul fur detector was avai lable to define the
central 1UO m or so of each pl ume traverse. The Cessna 206 general ly sampl ed at
points preselected by the B-23 crew. These points were chosen on the basis of
the real-time measurements aboard the B-23 and were relayed to the other
ai rcraft by radio.
-18-
SECTION 4
RESULTS OF THE FIELD STUDIES
4.1. The Data Base
In the course of the three field studies at the Mohave site, significant
data were obtained on twenty research fl ights. These fl ights are li sted in
Table 4.1. While most of these fl ights were in the late summer, two of them
were in the winter. Most fl ights were conducted during the early morning when
the plume was relatively stable. However, a number of afternoon fl ights were
also made to evaluate the effects of time of day on the physics and chemistry
of the pl ume.
From the twenty fl ights listed in Table 4.1, five fl ights (indi cated by
asterisks in Table 4.1) were selected for detai led analysis; the selection was
based on the completeness of the data sets.
4.2. Trace Gases and Light Scattering Coefficients
The gases of primary interest in this study (Og, NO, N0^, and SO^) were
al measured continuously aboard the B-23. Maximum values of each of these
variables are given in Table 4.2 for various ranges from the Mohave stack and at
various altitudes at a particular range. Because of the volume of data
invol ved, values are given only for the five fl ights for which detailed analyses
were performed. Al so given in Table 4.2 are values- of the measured maximum
values of the light-scattering coefficients due to particles (^at^’ In
general each value shown is the average of the maximum values measured at a
given range and altitude on several passes.
-19-
TABLE 4.1. Summary of B-23 Fl ights in whi ch Significant Data were Col lected in
the Pl ume from the Mohave Power Plant.
UW f1 ight number
710
*715
803
804
805
^806
^807
808^.
809
810
907
909
910
921
922
923
^924
926
928
929
Date
December 4, 1978
December 20, 1978
August 23, 1979
August 24, 1979
August 25, 1979
August 27, 1979
August 28, 1979
August 29, 1979
August 31, 1979
September 3, 1979
July 22, 1980
July 24, 1980
July 25, 1980
August 7, 1980
August 8, 1980
August 10, 1980
August 11, 1980
August 13, 1980
August 14, 1980
August 15, 1980
Time of day (Local
0730-0900
0730-0900
0715-1000
0630-0830
1330-1530
0600-1030
0600-1000
0600-0915
1100-1315
0615-0845
1400-1530
1300-1550
1400-1600
0430-0600
0430-0615
0830-1030
0730-1015
0730-0930
0650-0915
0715-0900
time)
* Selected for detai led analysis-see text,
>
TABLE 4.2. Maximum Concentrations of Various Trace Gases and Maximum Values of b Measured in the Mohave Plumes Cdcon Selected Days.
UW f1nurnbe
725
725
725
725
725
725
725
725
725
725
725
725
725
725
725
ight D.r
December
December
December
December
December
December
December
December
December
December
December
December
December
December
December
ate
20,
20,
20,
20.
20,
20,
20,
20,
20,
20,
20,
20,
20,
20,
20,
1978
1978
1978
"1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
Range
(km)
0.9
9.2
9.2
9.2
9.2
9.2
9.2
46.2
46.2
46.2
46.2
88.8
88.8
107
111
Al titude
(m)
594
406
453
469
531
594
656
432
469
531
563
547
719
719
625
SO^(PPb)
370
70
140
165
55
30
50
30
39
32
17
14
11
10
10
N0
(PPb)
900
85
195
211
75
90
135
30
23
30
15
N0^(PPb)
550
55
135
143
70
70
90
35
25
30
20
3(ppb
18
35
21
32
32
20
28
32
34
26
42
20
20
20
20
^cat(m-1)
0.21xl0"30.44xl0~40.85xl0’4No data
0.36xl0"40.38xl0’4
4 i0.45x10
c
No data
No data
No data
No data
No data
No data
No data
No data
Continued
* <
TABLE 4.2 (Continued) Maximum Concentration of Various Trace Gases and Maximum Values of b Measuredscatin the Mohave Plume on Selected Days.
UW flnumber
806
806
806
806
806
806
806
806
806
806
806
806
806
806
806
Continued
ght
August
August
August
August
August
August
August
August
August
August
August
August
August
August
August
Dat(
27.
27,
27,
27,
27,
27,
27.
27,
27.
27,
27,
27.
27.
27,
27,
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
Range
(km)
0.46
5.5
5.5
5.5
9.2
9.2
25.9
25.9
27.8
55.5
92.5
92.5
94.3
94.3
94.3
Altitude
(m)
781
719
750
781
719
781
812
844
812
875
938
969
969
1000
1031
SO,(Ppb)
470
680
727
545
375
820
135
125
148
130
50
57
58
60
65
N0
(PPb)
3000
760
750
500
375
950
75
55
87
80
0
0
0
0
0
N0.
(PPb)
1900
No data
No data
No data
No data
No data
100
90
95
85
50
35
35
40
32
0
(1
0
0
0
0
0
0
8
No
11
16
36
31
36
34
30
-> b3 scat
ppb) (m~
0.27xl0"30. 13xl0~30.16xl0"30. 16xl0~30.79xl0~4
i roo.i6xio’"3 r0.47xl0~4
data 0.42xl0"40.51xl0’40.41xl0~40.43xl0~40.44xl0~40.46xl0~40.44xl0"40.42xl0~4
TABLE 4.2 (Continued) Maximum Concentration of Various Trace Gases and Maximum Values of b Measuredscatin the Mohave Plume on Selected Days.
UW flnumber
806
8U6
807
807
807
807
807
807
807
807
807
807
807
807
807
ght
August
August
August
August
August
August
August
August
August
August
August
August
August
August
August
Dat
27.
27,
28,
28.
28,
28,
28.
28.
28.
28,
28,
28,
28,
28.
28,
e
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
Range
(km)
139
139
0.46
0.46
5.5
5.5
5.5
9.2
11. 1
27.8
27.8
27.8
27.8
55.5
55.5
Al titude
(m)
906
969
625
656
594
625
656
625
625
656
689
719
750
689
750
SO^(PPb)
23
25
1312
1250
560
477
320
120
200
60
115
110
90
28
29
N0
(PPb)
10
22
2125
1100
620
523
300
100
200
20
122
80
70
27
N0.
(PPb)
30
30
1050
500
350
250
220
100
120
20
60
55
55
35
3(PPb)
34
33
5
4
0
1.3
4
0
2
8
3
4
6
13
20
\c(m-
0.44xl0"40.45x10
0.13x10
0.12x10
0.63x10
0.63x10
0.56x10
0.33x10
0.43x10
0.32x10
0.36x10
0.40x10
0.33x10’
0.35xl0"40.34x10’
:at1 )
-4
-3
-3
-4
-4
A ^-^ r-o
-4
-4
-4
-4
-4
-4
-4
Continued
t*.
TABLE 4.2 (Continued) Maximum Concentration of Various Trace Gases and Maximum Values of b Measureds catin the Mohave Plume on Selected Days.
UW fl ighnumber
807
807
807
807
807
807
809
809
809
809
809
809
809
809
809
t
August
August
August
August
August
August
August
August
August
August
August
August
August
August
August
Dati
28,
28,
28,
28,
28,
28,
31,
31,
31,
31.
31,
31,
31.
31,
31,
e
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
Rar
(kir
55.
55.
92.
92.
92.
92.
0.46
5.5
5.
5.
5.
11.
11.
11.
11.
ige
>)
5
5
5
5
5
5
5
5
5
1
1
1
1
Altitudi
(m)
812
875
1031
1094
1156
1219
687
687
719
750
781
719
781
812
844
SO^(pPb)
31
24
18
23
13
19
570
340
325
245
210
70
77
70
40
N0
(PPb)
20
12
16
12
16
1175
420
425
297
320
45
55
52
20
N0^(PPb)
43
70
46
50
685
300
320
220
200
60
85
52
45
3(PPb)
16
20
24
18
26
27
2
8
5
6
7
24
23
26
44
scat
(m-1)
0.33xl0"40.30xl0~40.32xl0’40.33xl0~40.30xl0~40.32xl0"4
-A I\3
0.85x10 <^0.62xl0’40.58xl0"40.57xl0’40.57xl0"40.49xl0"40.48xl0’40.45xxl0"40.40xl0"4
Continued
TABLE 4.2 (Continued) Maximum Concentration of Various Trace Gases and Maximum Values of b Measureds catin the Mohave Plume on Selected Days.
UW fl ighnumber
809
809
809
924
924
924
924
924
924
924
924
924
924
924
924
t
August
August
August
August
August
August
August
August
August
August
August
August
August
August
August
Dati
31,
31,
31,
11.
11,
11.
11,
11,
11,
11,
11,
11.
11,
11.
11.
e
1979
1979
1979
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
Range
(km)
25.9
25.9
25.9
0.46
5.5
5.5
5.5
11. 1
11. 1
11. 1
22.2
22.2
22.2
37.0
37.0
Altitude
(m)
844
875
938
750
750
812
875
875
938
1031
875
938
828
844
875
SO^(PPb)
30
36
30
1050+
408
639
510
160
430
200
37
33
37
22
19
N0
(PPb)
595
250
470
360
40
310
110
50
50
40
50
35
N0^(PPb)
75
40-50
40-50
90
25
50
20
40
30
35
40
45
30
3(PPb)
50
54
54
11
6
2
2
13
2
4
23
22
20
20
26
scat
(.-1 )
0.44xl0"40.39xl0"40.40xl0’40.15xl0"30. 12xl0"30.16xl0"30. 12xl0’30.98xl0’40.12xl0"30. 15xl0"30.08xl0"40.08xl0"4O. lxlO"3O. lxlO"3O. lxlO"3
-25-
4.3. Size Distributions of Particles
Measurements of the size distributions of particles in the plume and
ambient ai r were used to determine parti cle number, surface area and volume con-
centration spectra. The number spectra are given in terms of dN/d(1og D), where
dN is the number concentration of particles between log D and log D + d(1og D).
The surface area spectra are given in terms of dS/d(1og D), where dS is the
corresponding surface area concentration of the particles. The volume spectra
are given by dV/d(1og D) where dV is the volume concentration of particles.
Measurements of the particles spectra are on fi le at the University of
Washington. Speci fic examples are presented in Section 5.4.
Particle data used in conjunction with the PHOENIX model (results from which
will be presented elsewhere) were further analyzed by performing a least-square
best fit to the data using an equation representing a multimodel log-normal size
distribution. Thus, the number spectra are represented by:
fD&n2^k N7dN y \ 1 px.
d^^- ill (^)1^ exp2 An^i
(4.1)
where, k is the number of modes (i .e. the number of log-normal distributions
requi red to describe the spectra) which is usual ly 2 or 3, N^ the total
particle number concentration in each mode, o. the geometric standard deviation
of each mode, and D. the geometric mean diameter of each mode. Surface and
2 3volume spectra are represented by analogous equations with S=TTD N and V=irD N,
respectively replacing N in Eq. (4.1). For further details on procedures the
reader is referred to Eitgroth and Hobbs (1979).
-26-
4.4 Fi lter Data
The most commonly employed fi lters were stretched Tefl on fi lters which
were used to determi ne parti culate sulfate and nitrate concentrations in
the pl ume and ambient ai r. These fi lters were analyzed for parti cul ate sul fate
and nitrate by means of ion-exchange chromatography (Stevens et a1 1978).
Volume concentrations of sul fate and nitrate were then cal culated from the
volume of ai r drawn through the fi lters. The standard error in the con-
centration measurement was general ly above +/-20%. Because each Tefl on fi lter had
to be exposed to the ai r for 10-15 min, it was only possible to acqui re a single
fi lter at each range from the Mohave stack for a given fl ight. Al of the
nitrate and sul fate data acqui red in the Mohave pl ume are listed in Table 4.3.
On a limited number of occasions during the 1980 fiel d experiment, suf-
ficient sampl ing time was avai lable to al low col lection of pl ume or ambient par-
ticles on quartz fiber fi lters, for subsequent analysis (by Dr. T. Novakov of
Laurence-Berkeley Laboratory) of the particle light-absorption coeffi cient. The
sampl e col lection was done by means of the 500 iter bag sampl e. Two techniques
were empl oyed to measure the absorption coefficient: the integrating pl ate
technique and the laser transmission technique. Both of these techniques are
discussed by -Sadler et a1 (1981) The particle absorption coefficients derived
from analysis of the quartz fi lters are shown in Table 4.4. Because most of the
particle absorption is assumed to be due to elemental carbon, one can derive
elemental carbon concentrations from the absorption data by means of empirical
-27-
TABLE 4.3 Concentrations of Sul fate and Nitrate Measured in the Plume from theMohave Power Plant and in the Ambient Ai r.
UW fl ightnumber
710
710
710
725
725
725
804
804
804
805
805
805
806
806
806
806
807
807
807
807
807
D
April
Apri
April
December 20, 1978
December 20, 1978
December 20, 1978
August
August
August
August
August
August
August
August
August
August
August
August
August
August
August
ate
12, 1978
12, 1978
12, 1978
20, 1979
20, 1979
20. 1979
25, 1979
25, 1979
25, 1979
27, 1979
27, 1979
27, 1979
27, 1979
28, 1979
28, 1979
28. 1979
28, 1979
28, 1979
Range
(km)
9.2
68.5
Ambient ai r
9.2
46.3
Ambient ai r
7.4
27.8
Ambient ai r
3.7
11. 1
Ambient ai r
5.6
27.8
92.6
Ambient ai r
5.6
27.8
55.6
92.6
Ambient ai r
^(ug m"
1.02
1. 30
1.07
0.63
0.96
0.79
0.24
0.55
0.28
0.38
0.08
0.30
0.92
0.36
0.89
0.22
0.69
0.39
0.20
0.39
0.37
N0-
(ug m
0.68
0.92
<0.25
0.47
0.28
0.35
0.22
0.24
0.21
0.09
0.00
0.08
0.00
0.06
0.00
0.02
0.00
0.04
0.01
0.00
0.00
-3
Continued
-28-
TABLE 4.3 (Continued) Concentrations of Sul fate and Nitrate Measured in thePlume from the Mohave Power Plant and in the Ambient Ai r.
UW fl ightnumber
808
808
808
808
809
809
809
809
810
810
810
907
907
909
909
909
910
910
910
Continued
Date
August 29, 1979
August 29, 1979
August 29, 1979
August 29, 1979
August 31, 1979
August 31, 1979
August 31, 1979
August 31, 1979
September 3, 1979
September 3, 1979
September 3, 1979
July 22, 1980
July 22, 1980
July 24, 1980
July 24, 1980
July 24, 1980
July 25, 1980
July 25, 1980
July 25, 1980
Range
(km)
5.6
27.8
55.6
Ambient ai r
5.6
11. 1
25.9
Ambient ai r
5.6
25.9
Ambient ai r
5.6
Ambient ai r
5.6
22.2
Ambient ai r
5.6
27.8
Ambient ai r
SO^(ug m"
0. 17
0.41
0.45
0.23
1. 19
0.63
0.71
0.05
0.98
0.39
0. 16
3. 15
2.54
3. 70
3.23
1.76
4.44
2.54
3.67
N03-3(ug m
0.03
0. 10
0.08
0.03
0.13
0.12
0.13
0.01
0.10
0.02
0.01
1.16
2.51
0.00
0.00
0.00
0.31
0.00
0.00
-29-
TABLE 4.3 (Continued) Concentrations of Sul fate and Nitrate Measured in thePl ume from the Mohave Power Plant and in the Ambient Ai r.
Ul-J fl ightnumber
921
921
921
922
922
922
923
923
923
923
924
924
924
926
926
929
929
929
Date
August 7, 1980
August 7, 1980
August 7, 1980
August 8, 1980
August 8, 1980
August 8, 1980
August 10, 1980
August 10, 1980
August 10, 1980
August 10, 1980
August 11, 1980
August 11, 1980
August 11, 1980
August 13, 1980
August 13, 1980
August 15, 1980
August 15, 1980
August 15, 1980
Range
(km)
5.6
37.0
Ambient ai r
5.6
27.8
Ambient ai r
5.6
11. 1
37.0
Ambient ai r
5.6
37.0
Ambient ai r
5.6
37.0
5.6
37.0
Ambient ai r
SO^(yg m’
4.18
3.49
3.26
3.36
3.75
4.12
2.44
3.09
3.22
4.06
3.25
3.22
3.25
3. 12
4.02
4.15
1.90
4.93
3)
0. 16
N0-
3(ug m
2.04
0.85
0.99
0.00
0.00
0.00
0.55
1.05
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.40
0.78
TABLE 4.4 Particle Absorption Coefficients (b^) and Elemental Carbon Concentrations Measured In and Around the
Mohave Plume.
UW fl ight Date Location b v b 2/ Carbonnumber au ab
916
919
920
920
923
924
925
925
926
August
August
August
August
August
August
August
August
August
4.
5.
6,
6,
10,
11,
12,
12,
13.
1980
1980
1980
1980
1980
1980
1980
1980
1980
Ambient ai
Ambient ai
Ambient ai
Ambient ai
Plume (0.46 km downwind)
Plume (5.6
Ambient ai
Ambient ai
Plume (0.4
r
r
r
r
km downwind)
r
r
6 km downwind)
(m"1
0.39xl0’41.2xl0~40.61xl0"40. 14xl0"40.62xl0~40.20xl0~4<0.08xl0’43.04xl0"4
<0.16xl0~4
0.
U.
0.
0.
0.
0.
<0.
1.
<0
(n-1
25x10
76x10
38x10
09x10
39x10
13x10
05x10
93x10
10xl0~4
-4
-4
-4
-4
-4
-4
-4
-4
(ng (T
1.
6.
3.0
0.
3.
1.
<0.4
1.
<0.
.-3)
9
0
7
1
0
5
8
]_/ Measured by laser transmission
2/ Measured by integrating plate
-31-
calibrations. El emental carbon concentrations derived in this manner are al so
shown in Table 4.4. Si nce no ambient quartz filter samples for carbon analysis
were taken on those days that we were studying the Mohave pl ume in detai we
have empl oyed ambient samples taken on days when we were engaged in regional
studies of the effects of the pl ume.
In addition to the quartz and Teflon fi lters exposed from the B-23 ai rcraft
duri ng the 1980 field experiment, high-volume fi lter samples (11.1 cm diameter)
were exposed from the Cessna 206. A dual-fi lter pack was empl oyed for each
sample. The back fi lter was a fast-flow, acid-washed, cel lul ose fi lter
impregnated with 25% KpCO, and 10% glycerine. The front filter was acid-washed
quartz. These fi lters were extracted and the extraction solution analyzed both
by ion-chromatography and thermochemical ly. Analyses were done for the fol lowing
species: organic and inorgani c sul fur (IV) N0, NO,, SO", C1", Na’1’, NH.’1’ and
K A1 of the pl ume samples were obtained by orbiting in the pl ume between 11
and 19 km from the stack. The results of the analyses are shown in Table 4.5.
No NOp was detected in any of the sampl es.
4.5 Impactor Data
During the 1980 field experiment, cascade impactor samples were exposed
from the Cessna 206. The impactors were low volume (1 liter per min) 5-stage
devi ces, with a membrane fi lter substrate. The particle size cuts of the
impactor were such that particles were separated into diameter ranges <0.45 urn,
0.45-1.05 pm, 1.05-2.30 pm, 2.30-4.65 urn and >4.65 urn. The analyses of the
filters (by Dr. D. Eatough) was by means of PIXE. Whi le analysis was carried
out for 21 elements, the four elements vanadium, strontium, bismuth and selenium
were never found in the pl ume and are therefore not listed in the tables.
TABLE 4.5 Concentrations (in umol in-3) of Various Species Col lected in High-Volume Fi lter Sampl es in the_______Mohave Plume. Al Plume Samples were Obtained at a Range of 11 to 19 km from the St a ck.
UH fl ight Date Plume (P)/ Inorganic Organi c SO"NO"NH +C1
number Ambient (A)____S(IV)_____SfIV) 4 3 4907 July 22, 1980 P 070-64^---TO2T5------0701-5--07015--CCT80---OTO^T907 JU1.y 22. ^SO A 0.045 0.019 0.015 0.015 0.085 0.095
909 ^y 24. 1980 P <0.01 <0.01 0.009 0.009 0. 12 0.12
909 ^V 24. 1980 A <0.01 <0.01 0.007 0.007 0. 11 0.21
910 ^V 25. 1^0 P <0.01 <0.01 0.021 0.021 0.092 0.071
910 ^y 25. 198() A <0.01 <0.01 0.017 0.017 0.090 0.087
921 August 7, 1980 P <0.01 <0.01 0.022 0.022 0.058
921 August 7, 1980 A <0.01 <0.01 0.008 0.008 0. 10 0.28
922 August 8, 1980 P <0.01 <0.01 0.018 0.018 0.067 0.030
922 August 8, 1980 A <0.01 <0.01 0.012 0.012 0.096 0.076
923 August 10, 1980 P <0.01 <0.01 0.018 0.018 0.043 0.032
923 August 10, 1980 A <0.01 <0.01 0.004 0.004 0.146 0.697
924 August 11, 1980 P <0.01 <0.01 0.020 0.004 0.114 0.44
924 August 11, 1980 A <0.01 <0.01 0.004 0.020 0.092 0.063
926 August 13, 1980 P 0.0095 <0.01 0.019 0.002 0.080 0.039
926 August 13, 1980 A <0.01 <0.01 0.004 0.005 0. 11 0.042
929 August 15, 1980 P 0.14 <0.01 0.020 0.012 0. 12 0.077
929 August 15, 1980 A <0.01 <0.01, 0.023 0.012 0. 12 0.030
-33-
A total of seven impactor samples were taken in the Mohave pl ume. The
results of the analyses of these samples are shown in Table 4.6. For com-
parative purposes, two impactor samples were taken near Los Angeles, in the
urban pl ume of that city, and two were taken in Zi on National Park. The latter
may be assumed to be representative of background conditions in the regi on
surrounding the Mohave power pl ant. The results of the analyses of these urban
and background samples are shown in Table 4. 7.
4.6 Telephotometer Data
During the course of the 1979 and 1980 Mohave field studies, ground-based
telephotometer measurements were made by SCE personnel An attempt has been
made to compare our ai rborne measurements of the particulate scattering coef-
fi cients and light-absorbing gases in the Mohave plume and the optical bright-
ness measurements made with the telephotometer.
The telephotometer used was a Meteorology Research Inc. (MRI Vi sta
Ranger, Model 3010. This instrument measures the apparent brightness of
selected targets and of the sky at four manual ly selected narrow wavelength
bands centered at 405, 450, 550 and 630 nm. By comparing the apparent bright-
ness of a target with and without the pl ume between the target and the observer,
the optical depth T of the pl ume can be determined at the selected wavelengths
by means of the Beer-Lambert relationship:
-f- 6"’ (4.2)o
where, B and B^ are the brightness of the target in the presence of and in the
absence of the pl ume, respectively. The sky was general ly selected as the target.
-34-
i
TABLE 4.6 El emental Concentrations (in ug m" by Si ze in Particles Col lectedin the Mohave Plume.
(a) UW FLIGHT 907, 22 JULY 1980: 16: 54-17: 27 LST; 11. 1 KM FROM STACK.
Element _______________Impactor Stage__________
1 2 3 4 5
P o.044S 0.474 0.022 0.333 0. 161C1 3.082 0.084 0. 108 0.285K 0.927 0.054 0.085 0.230Ca 0. 178 0. 133 2.007 0. 168 0. 146Ti 0.012 0. 158 0.021 0.021Cr 0.068 0.003 0.004Mn 0.004 0.002 0.003 0.003Fe 0.066 0.050 0.090 0.067CoN1 0.001 0.003 0.004 0.004Cu 0. 132 0.012 0.007 0.008 0.011Zn 0.016As 0.005 0.004Br 0.030 0.018Pb
(b) UW FLIGHT 910, 25 JULY 1980: 16: 18-16: 55 LST; 11-18 KM FROM STACK.
Element__ ____________Impactor Stage___________
1 2 3 4 5
Si 0. 108P 0.105 0.079S 0.149 0.556 0.427 0.110 0. 141C1 1. 757 0.055 0. 182K 0.087 0.063 0.067 0.059 0.102Ca 0. 110 0.053 0.011 0.068 0. 108Ti 0.003 0.004 0.012Cr 0.211Mn 0.003 0.0038Fe 0. 118 0.056 0.012 0.024 0.063Co 0.0003 0.0004Ni 0.002Cu 0.004Zn 0.002
Br 0.024Pb
* Impactor stage I particles: <0.45 pm, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 urn, stage 4: 2.34-4.6 urn, stage 5: >4.6 urn. A dash in the tableindicates that the element was not detected.
Continued
-35-
TABLE 4 -3,,6 (Continued) El emental Concentrations (in ug m by Size in ParticlesCol lected in the Mohave Plume.
(c)
Element
SiPSC1KCaTiCrMnFeCoNiCuZnAsBrPb
(d)
Element
S1PSC1KCaTiCrMnFeCoNiCuZnAsBrPb
2.259
0.0931.296
0. 113
0.4051.840
0.078
0.087
0.074
0.0010.128
UW
UW
FLIGHT 921,
1
0.268
FLIGHT 922,
1
0.0440.032
7
8
0.4470.081
AUGUST 1980:
2
0.073
0.301
0.0010.0260.081
0.022
0.0010.003
AUGUST 1980:
2
0.0760.019
0.008
05:25-06:05 LST; 12. 1 KM FROM STACK.
Impactor
3
0.033
0.197
0.0500.075
0.006
0.0470.0010.001
0.0080.004
05:23-05: 59 LST; 19 KM
Impactor
3
0.309
0.0420.015
0.058
0.005
Stage
4
0. 7930.0170.0260.3380.0110.0020.0030.064
0.006
*Stage
4
0. 1170.1110.0810.0720.041
0.038
0.0030.001
0.005
5
0.0120. 1020.009
0.002
FROM STACK.
5
0.2790. 101
0.0330.033
0.0120.00390.0037
0.001
0.004
* Impactor stage I particles: <0.45 urn, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 urn, stage 4: 2.34-4.6 urn, stage 5: >4.6 ym. A dash in the tableindi cates that the element was not detected.
Continued
-36-
TABLE 4.6 (Continued) El emental Concentrations (in \iq m" by Si ze in Parti clesCol lected in the Mohave Plume.
(e)
Element
S1PSC1KCaTiCrMnFeCoNiCuZnAsBrPb
(f)
Element
S1PSC1KCaT1CrMnFeCoNiCuZnAsBrPb
UW
0.087
1.126
0.136
0.008
0.0060.1710. 109
UW
2. 1500. 167
0.138
0.115
FLIGHT 923,
1
0.044
0.3940.081
FLIGHT 926,
1
3.750
0.041
0.050
0.013
10
13
AUGUST 1980:
2
0.3960.0810. 1420.0940.0250.007
0.081
0.0010.039
AUGUST 1980:
2
0.647
0.1160.0900.017
0.042
0.0020.028
0.0256
10:08-10:
Impactor
3
0.3620.1430. 1090.1270.0180.0070.0040.081
0.0010.045
0.075
09:23-10:02 LST; 18.5
Impactor
3
0.380
0.378
0.003
0.001
43 LST; 13.0
^Stage
4
0.1130.0530.0630. 1020.007
0.0020.035
0.0020.023
*Stage
4
0. 1490.027
0.003
0.008
0.006
0.001
KM FROM STACK.
5
0.1410.0670.0540.023
0.012
KM FROM STACK.
5
0.1380.0250.0130.016
0.0247
0.004
* Impactor stage I particles: <0.45 pm, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 urn, stage 4: 2.34-4.6 pm, stage 5: >4.6 urn. A dash in the tableindi cates that the element was not detected.
Continued
-37-
_3TABLE 4.6 (Continued) El emental Concentrations (i n pg m by Si ze in Particles
Collected in the Mohave Pl ume.
(g) DM FLIGHT 929, 15 AUGUST 1980: 09: 20-09: 55 LST; 11. 1 KM FROM STACK.
Element
SiPSC1KCaTiCrMnFeCoNiCuZnAsBrPb
1
3.600
0.1362.040
0.1220.012
0. 141
2
0.695
0.0720.06170.008
0. 121
0.0070.230
Impactor S1
3
0.544
0.0180.0060.0030.077
0.0010.014
*:age
4
0.073
0.003
0.010
0.003
5
0.0920.052
0.00380.004
0.009
* Impactor stage I particles: <0.45 urn, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 \im, stage 4: 2.34-4.6 pm, stage 5: >4.6 urn. A dash in the tableindi cates that the element was not detected.
-38-
TABLE 4. 7 El emental Concentrations (in pg m" by Size in Parti cles Col lectedin Aged Urban Ai r (a and b) and in Cl ean Background Ai r (c and d)
(a) UW FLIGHT 917, 4 AUGUST 1980: AT 17: 49-18: 20 LST. THE SAMPLES WERECOLLECTED 9-11 KM EAST OF TWENTY-NINE PALMS, CA
S1PsC1KCaTiCrMnFeCoNiCuZnAsBrSrPb
Element Impactor Stage
1
0.2340. 192
0. 172
0. 104
2
0.439
0.073
0.011
0.016
0.0030.006
3
0. 7640. 1960.2090.0480.011
0.042
0.0020.008
4
0.0260. 1400.2010. 1350.0640.0100.0030.0020.040
0.0010.004
5
0.0460.3010.0060. 2030. 1440.025
0.085
0.0190.010
0.045
(b) UW FLIGHT 919, 5 AUGUST 1980: AT 11: 51-12:22 LST. THE SAMPLES WERECOLLECTED FROM CADIZ, CA TO 13 KM NORTHWEST OF RICE, CA
Element Impactor Stage
SiPSC1KCaTiCrMnFeCoNiCuZnAsBrSrPb
1
0. 1620. 7561.911
0.0290.005
0.1500.038
2
0.0090.343
0.005
0.010
0.023
0.0240.012
0.081
0.041
30. 1180.1480.4000.0850.0750.0370.019
0.0340.0030.0100.018
40. 142
0.0650.0370.0750.0620.0090.003
0.0280.0060.0020.0150.003
50. 116
0. 1890.0780. 1270.1100.027
0.0930.004
0.0200.0120.006
Impactor stage I particles: <0.45 pm, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 pm, stage 4: 2.34-4.6 urn, stage 5: >4. 6 urn. A dash in the tableindi cates that the element was not detected.
Continued
-39-
-3,TABLE 4.7 (Continued) El emental Concentrations (i n \ig m by Size in Particles
Col lected in Aged Urban Ai r (a and b) and in Cl ean Background Ai r (c and d)
(c) UW FLIGHT 920, 6 AUGUST 1980: AT 11: 11-11:42 LST. THE SAMPLES WERECOLLECTED 10 KM W TO 5 KM SOUTH OF ZION NATIONAL PARK
Element Impactor Stage
SiPSC1KCaTiCrMnFeCoNiCuZn/\sSeBrPb
(d) UW FLIGHTCOLLECTED
Element
SiPSC1KCaTiCrMnFeCoNiCuZnAsSeBrPb
1
0.3332.104
0.089
0. 128
925.30 KM
1
2.341
0.0670.006
0.1660.021
0.23
2
0. 1090.315
0.0550.0260.013
0.036
0.004
0.008
12 AUGUST 1980EAST OF ZION
2
0.2980.3880.0540. 1680.0690.0050.0050.0030.025
0.0010.022
0.007
3
0.464
0.0300.0240.008
0. 119
0.011
0.003
AT 12:00-NATIONAL PARK
Impactor
3
0.5810.002
0.005
0.0020.013
0.0020.003
4
0.0440. 189
0.0180.0430.006
0.034
0.0020.003
.12: 31 LST.
^Stage
4
0.601
0.001
0.001
5
0.0650. 1750.0400.0530.1600.0780.0020.0050.178
0.011
THE SAMPLES WERE
5
0.0820.0550.385
0.007
0.0020.056
0.003
Impactor stage I particles: <0.45 urn, stage 2: 0.45-1.05 urn, stage 3:1.05-2.3 prn, stage 4: 2.34-4.6 urn, stage 5: >4.6 urn. A dash in the tableindi cates that the element was not detected.
-40-
Whi le the light extinction coefficient can, in principl e, be easi ly
derived from the optical depth, we have chosen to use optical depth as our fun-
damental unit for comparison with the measurements. Therefore, we do not
process the telephotometer data beyond deriving T ’S. Furthermore, we have cho-
sen not to present the relatively meaningl ess raw brightness measurements but to
start our di scussion with the optical depth values. These values are presented
n Section 6.3.
4. 7 Plant Loadings
Whi le some effort was made to maintai n the output of the Mohave pl ant
constant during the periods of our ai rborne sampl ng, this was not always
possi ble and some variations in plant output from fl ight-to-fl ight were observed.
This can be seen in (Table 4.8).
-41-
TABLE 4.8 The Ranges of Power Loadings for the Mohave Power Plant During the
Fi ve Research F1 ights of the B-23 Ai rcraft for which Detai led Analyses
were Carried Out. The Average Power Loads are for a Period that
Commenced Three Hours Prior to Fl ight Time and Ended at the
Termination of the Fl ight.
UW fl ightnumber
725
806
807
809
924
Date
December 20, 1978
August 27, 1979
August 28, 1979
August 31, 1979
August 11, 1980
Average power load(MW)
600-700
1200-1300
1200-1300
800-900
1000-1100
-42-
SECTION 5
ANALYSIS OF THE FIELD -DATA
5.1 Geometry of the Plume
The shapes and horizontal extents of the pl ume from the Mohave power pl ant
are determined by the topography of the surrounding area as wel as by meteoro-
ogical conditions.
In the vi ci nity of the Mohave pl ant the Colorado Ri ver Val ley is enclosed
on the east and west by ridges, which rise to over 1500 m above mean sea level
and roughly 1200 above the val ley fl oor (Fig. 5.1). These ridges continue for a
distance of ~65 km to the north of the plant, creating a channel ~18-28 km wide.
South of the plant the terrain is much less restrictive but there is stil a
wel l-defined channel extending as far south as Needles, Cal ifornia, which is
located about 37 km south of the plant. As a consequence of these topographical
features, winds are often channel led north or south of the Mohave pl ant; the
flow is generally from the north in summer and from the south in winter.
Under conditions of southerly fl ow the plume is carried north up the
Colorado River Val ley with little chance for lateral di ffusion out of the val ley
unti a gap in the mountains on the east side of the channel is reached at ~65
km north of the plant. This gap stil has a minimum elevation of ~900 m MSL.
Only at ~100 km north of the Mohave plant does the val ley widen into a large basin,
whi ch encompasses Las Vegas to the west and the entrance to the Grand Canyon to
the east. This basin, which is 130 km west to east and ~90 km north to south,
contains Lake Mead. It is in this basin that the Mohave plume mixes extensively
with the regional ai r.
Figure 5. 1 The topography of the region surrounding the Mohavepower plant is shown. The shaded areas are above 9 15 m MSL.Peak altitudes within the ehaded areas are given In meters MSL.
-44-
Under conditions of northerly fl ow, the Mohave pl ume moves south through
the Mohave Val ley, experiencing considerably more mi xi ng with the regional ai r
than is the case with a southerly fl ow.
To determine the horizontal extent of the pl ume in individual cases, the
measurements obtained aboard the B-23 ai rcraft were used to construct isopleths
of b and/or SO,, concentration. Maximum values observed along the pl ume cen-scat <-
terl ine were used in determining the isopleths. Since the terrain and, con-
sequently, the altitude of the pl ume centerl ine, vary considerably over any
given pl ume trajectory, such pl ots are not precisely x-y pl ots. Furthermore, if
ambi-ent concentrations of SO? and b vary appreciably with altitude, the
plotting procedure can produce spurious trends in the horizontal extent of the
plume as a function of range. Fortunately, little such verti cal variation
occurred over the vertical extents of the pl umes that we chose for detai led
studies, as can be seen from Fig. 5.2.
Examples of these pseudo x-y pl ots for SO? and b are shown in Fi gs.
5.3 and 5.4, respectively, for the case study of 27 August 1979. The b plot
clearly shows the infl uence of topography on the trajectory of the plume. A
more pronounced example of this effect can be seen in pl ots of SO? and b for
the case study of _28 August 1979 (Fi gs. 5.5 and 5.6) which reveal that the plume
essential ly spl it into two as it encountered the high mesa just south of Lake Mead.
Further examples of the horizontal extents of the Mohave plume in southerly
flow are shown in Fi gs. 5.7-5.9. On the 31 August 1979 both SO? and b show
a discernable pl ume only out to about 20 km (Fi gs. 5.7 and 5.8). On the 11
August 1980 the horizontal extent of the pl ume, as determined by SO? concentrations,
extends ~35 km north of the power plant (Fig. 5.9).
1
0
^CAT (IN UNITS OF IO^M-’0.2 0.4 0.6 0.8 1.0 1.2 1.4
( a ) 5.6 Km
1.6
^\
SOz xMAXIMUM \tJAVALVE
/.*>SCAT
0 50 100 150 200 250 300 350 400SOg CONCENTRATION (PPB)
Figure 5.2 Sulfur dioxide concentrations and light-scatteringcoefficient (bacap 1n the Mohove plume (solid lines) and In the
omblent air (dashed lines) on 27 August 1979 at ranges north ofthe plant of (a) 5.6 km, (b) 28 km, (c) 93 km, and (d) 1 85 km.
>
9210
tosCAT CN UNITS OF IO-^M-I)
0-1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
( b) 28 Km
922-^ ’’SCAT
923
m2
SO2MAXIMUMVALVE
HJ
^ 9240)(/)
0:0.
925
926-1
927-^
9280 10 20
//30 40 50
SOg CONCENTRATION
Figure 5.2 (continued) Sulfur dioxide concentrations ondllght-scottoring coefficient (bg^) in the Mohove plume (solidlines) and In the ambient air (dashed lines) on 27 August 1 979at ranges north of the plant of (a) 5.6 km. (b) 28 km. (c) 93 kmand (d) 185 km.
0.’’SCAT (IN UNITS OF lO4!^ 1)
0.2 0.3
( C ) 93 Km
906
90S
CD2
910
912
H/
\\\SO,
9180 10 20 30
SOg CONCENTRATION (PPB)
Figure 5.2 (continued) Sulfur dioxide concentrations andlight-scattering coefficient (b^^) in the nohave plume (solidlines) and In the ambient air (dashed lines) on 27 August 1979at ranges north of the plant of (a) 5.6 km. (b) 28 km (c) 93 kmand (d) 165 km.
bSCA^ (IN UNITS OF lO4!^’1)0 0. 0.2 0.3 0.4
( (j ) 185 Km
SO-
SCAT
SO- ’SCAT
0 10 20 30
SO^ CONCENTRATION (PPB)
40
Figure 5.2 (continued) Sulfur dioxide concentrations endlight-scattering coefficient (bg^) In the Mohave plume (solid
lines) and In the ambient air (dashed lines) on 27 August 1979at ranges north of the plant of (a) 5.6 km, (b) 20 km, (c) 93 km,and (d) 105 km.
Figure 5.3. Point measurements and derived isopleths of SO, concentrations (in ppb) downwind of theMohave power plant on 27 August 1979. The shaded areas are above 915 m MSL.
Figure 5.4. Point measurements and derived isopleths of light-scattering coefficients (in units of lO’4^1)downwind of the Mohave power plant on 27 August 1979. The shaded areas are above 915 m MSL. Thevalues at Las Vegas were derived from visual range measurements.
-51-
Figure 5.5. Point measurements and derived isopleths of SO, concentrations (in ppb) downwind of theMohave power plant on 28 August 1979. The shaded areas are above 915 m MSL.
-52-
Figure 5.6. Point measurements and derived isopleths of light-scattering coefficients (in units of lO^m 1)downwind of the Mohave power plant on 28 August 1979.
Figure 5.7. Point measurements and derived iop(eth< of SO, concentrations (in oob) downwind^lrSBiMohave power plant on 31 August 1979. The shaded areas are above 915 m MSLaownw’^" ^’fc
Figure 5.8. Point measurements and derived isopleths of light-scattering coefficients (in units of lO^m’1)downwind of the Mohave power plant on 31 August 1979. The shaded areas are above 915 m MSL.
Figure 5.9. Point measurements and derived isopleths of SO; concentrations (in ppb) downwind of theMohave power plant on 11 August 1980. The shaded areas are above 915 m MSL.
-56-
Although only two fl ights of any duration have been made under northerly
fl ow, under such conditions the extent of the Mohave pl ume appears to be much
more defined than for southerly flow. A plot of SO? concentrations downwind
of the Mohave pl ant on 20 December 1978 is shown in Fig. 5. 10. In this case,
the pl ume extended for more than 4U km downwi nd and passed over Needles.
The vertical extent of the Mohave pl ume has been examined using the pl ots
of various plume constituents in both the y-z and x-z planes (see Fi g. 3.3 for
coordinate system) The y-z plane is useful because its data density is intrin-
sical ly high. The x-z plane is useful because it shows more clearly variations
in the vertical extent of the plume with range from the stack, and it is also
the plane that is most readi ly observed. It shoul d be kept in mind that a1 of
the cross sections described in this report invol ve an assumption concerning the
comparabi ity of measurements taken at di fferent times. The figures actual ly
show cross sections of the time-averaged pl ume, rather than the instantaneous
plume. Al so, the averaging times for the di fferent cross sections are not the
same. For example, the y-z cross sections invol ve averaging over only about an
half-hour, whereas, the x-z cross sections invol ve several hours of averaging.
Examples of x-z cross sections for various pl ume constituents measured on
the 27 August 1983 are shown in Fig. 5.11. (Plots for the other four fl ights
for which we carried out extensive analyses are included in Appendices A-D. It
can be seen from this figure, that the precise shape of the discernable plume
depends on the detection limit and background level of the constituent employed
to define the plume.
E31_as Vegas
Figure 5.10. Point measurements and derived isopleths of SO, concentrations (in ppb) downwind of theMohave power plant on 20 December 1978. The shaded areas are above 915 m MSL.
(a ) so?
Esc
0.75LUQ3
< 0.50-^
s
^ .23
23
cn00
0.25-^
00 20 40 60 80 100
DISTANCE FROM PLANT (Km
120 140
Figure 5.11 Point measurements and derived isopleths in the x-z plane along the center line of the plume from theMohave power plant on UW Flight 806 (on 27 August 1979). Open circles denote measurements taken on return flight.(a) SO, concentrations in ppb, (b) NO concentrations in ppb, (c) NO 2 concentrations in ppb, (d) ozone concentrationsin ppb, and (e) bgcatin ""its of 10’ *nf\ Isopleths are shown as solid lines where they are reasonably well defined andas dashed lines where they are more uncertain.
( b) NO
E^luQ3
<01U)
60 80 100
DISTANCE FROM PLANT (Km)
Figure 5.11 (continued) Point measurements and derived isopleths in the x-z plane along the center line of the plumefrom the Mohave power plant on UW Plight 806 (on 27 August 1979). Open circles denote measurements taken onreturn flight, (a) SO, concentrations in ppb, (b) NO concentrations in ppb, (c) NO, concentrations in ppb, (d) ozone con-centrations in ppb, and (e) bscatin ""’ts of 10 ’*m’\ Isopleths are shown as solid lines where they are reasonably welldefined and as dashed lines where they are more uncertain.
(C ) N02
1.25
1.00
30.^,0
/-30
30
<0.50H
/100
^ 0)0
0.25-^
00 20 40 60 80 100
DI STANCE FROM PLANT (Km)120 140
Figure 5.11 (continued) Point measurements and derived isopleths in the x-z plane along the center line of the plumefrom the Mohave power plant on UW Flight 806 (on 27 August 1979). Open circles denote measurements taken onreturn flight, (a) SO; concentrations in ppb, (b) NO concentrations in ppb, (c) NO; concentrations in ppb, (d) ozone con-centrations in ppb, and (e) bscat in units of 10 -4m’1- Isopleths are shown as solid lines where they are reasonably welldefined and as dashed lines where they are more uncertain.
( d ) 3
1.25
\
M-’1.0031 <2_^ : ’36
E^
16
/ ^--.0 0 00.750* /0’ 0u
Q3
/
-i 0.50-14
0.25 d
0
34. \
33 \
36
/>
0>
0 20 ^0 60 80 100
DISTANCE FROM PLANT (Km)
120 140
f^^’M1^^^^^^^ p?i"t me?^rc.m?nts and derived iso^e^" the x-z plane along the center line of the plumer^m tS^S? /^ wer plar?^ uw F"glLt 806 (y 27 August 1979)- OPen circles denote measurements taken oncent^S^^^^ n ppb (b) NO concentrations in ppb. (c) NO, concentrations in ppb, (d) ozone con.SeSneS andS^S^ e) b8caKt ’" umts of 10 m ^eths are shown as solid lines where they are reasonably welldenned and as dashed lines where they are more uncertain.
(e ) bSCAT
1.25
.0.44,
^ 0.754
<
’0.40.44 0.42’
^ o.4e\<^-"0.43*0.4S\0.44/
>’0.4.
oM
0.5CH
0.25 -^
0--0 20 40 60 80 100
DISTANCE FROM PLANT (Km
120 140
Figure 5.11 (continued) Point measurements and derived isopleths in the x-z plane along the center line of the plumefrom the Mohave power plant on UW Flight 806 (on 27 August 1979). Open circles denote measurements taken onreturn flight, (a) SO, concentrations in ppb, (b) NO concentrations in ppb. (c) NO, concentrations in ppb, (d) ozone con-centrations in ppb, and (e) b scat in units of 10 -"m-1. Isopleths are shown as solid lines where they are reasonably welldefined and as dashed lines where they are more uncertain.
-63-
Nevertheless, there is some consistency in the pl ots. For exampl e, the shapes
of the plume defined by NO? and b (the two parameters of most relevance in
vi sibi lity) are rather simi lar. Interestingly, for most of the pl ume consti-
tuents shown in Fi g. 5.11, a rather novel feature appears at a range of ~90 km;
after being perturbed upwards the plume appears to have been restored to an
equi ibrium position at this range. Me specul ate that the perturbation was
caused by the passage of the pl ume over the Mt. Mi son Mesa.
Exampl es of y-z cross sections for SO? at various ranges downwind of the
Mohave power pl ant are shown in Fi g. 5.12 (further exampl es are shown in
Appendix B). Perhaps the most interesting point il lustrated by these cross sec-
tions is the lack of appreciable vertical di ffusion of the plume. The vertical
extent of the plume (~128 m) at a range of 139 km is essential ly the same as
at a range of 5.6 km. However, the horizontal dimensions of the plume
ncreased by more than a -factor of 2 over the same range interval Furthermore,
the ratio of the width of the pl ume to its vertical thickness, even at 5.6 km,
is 48: 1. This lack of vertical di spersion, which reflects the stabi ity of the
ai r, was fai rly typi cal of conditions encountered on summer mornings.
The "pancake-shaped" plume has some interesting impl cations with respect
to visual impact. For example, an observer below the pl ume wi see an opti-
cal ly thin plume when viewing it at angles anywhere near the verti cal On the
other hand, an observer viewing the plume from about the same height as the
pl ume (say from one of the ridges above the Colorado Ri ver Val ley) wi see a
relatively opti cal ly thick pl ume, even at a considerable di stance from the
pl ant.
( Q ) X = 5.6 Km
W
0.80
0.75
0.65-^
0.60-L2.0 0 2.0 4.0
DISTANCE (Y) FROM CENTER OF PLUME Km
IL10"^ 5 1 2 po<nt ’"""^^nts ond derived Isopleths of sulfurd oxide concentrations (In ppb) In the u-z plane of the MohoveP’ .To^o^s^""81^^^ F;lght 806) flt -"0- ^ ^m^them n in^ /k ’ (b) 9 2 km’ (c) 28 km’ (d) 92 ltm- "" (c) 1 39km. B indicates background concentration.
( b) X = 9.2 Km
W
0.85
Eac
LJQ=)
1-
<
0.80-^
0.75
0.7CH
0.652.0 0 2.0 4.0 6.0
DISTANCE (Y) FROM CENTER OF PLUME (Km)
Figure 5. 12 (continued) Point measurements end derivedisopleths of sulfur dioxide concentrations (in ppb) In the y-zplane of the Mohave plume on 22 August 1 979 (UW Flight 006) atranges (x) from the plant of (a) 5.6 km, (b) 9.2 km, (c) 28 km, (d)92 km, and (e) 1 39 km. B Indicates background concentration.
( C ) X = 28 Km
W -<----- E
0.9(^
E 0.85^LJQ3
(= 0.80_i
<
0.75
8^20
0.706 4 2 0 2 4
DISTANCE (Y FROM CENTER OF PLUME Km
Figure 5. 12 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on 22 August 1 979 (UW Flight 006) atranges (x) from the plant of (a) 5.6 km, (b) 9.2 km, (c) 28 km, (d)92 km, and (e) 1 39 km. B Indicates background concentration.
( d ) X 92 Km
W
19:8
4 2 0 2 4 6DISTANCE Y FROM CENTER OF PLUME
Figure 5. 1 2 (continued) Point measurements and derivedIsopleths or eulfur dioxide concentrations (in ppb) in the y-zplane of the Mohove plume on 22 Auguet 1 979 (UW Flight 006) etrangee (x) from the plant of (o) 5.6 km, (b) 9.2 km, (c) 28 km. (d)92 km, and (e) 1 39 km. 0 Indicates background concentration.
( e ) X = 139 Km
W -<----- E
16 19
12 10 8 6 4 2 0DISTANCE (Y FROM CENTER OF PLUME (Km)
Figure 5. 1 2 (continued) Point measurements and derivedleopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Moheve plume on 22 Auguet 1 979 (UW Flight 806) otranges (x) from the plant of (a) 5.6 km, (b) 9.2 km, (c) 28 km. (d)92 km, and (e) 1 39 km. B Indicates background concentration.
-69-
The ratio of the width-to-the-height of the pl ume was not always as great
as those measured during summer mornings. For example, measurements taken on 20
December 1978 (see Appendix B) show that the ratio of the plume width-to-height
of the plume was always less than 20: 1.
5.2 NO-to-NO? Conversion
There are only two constituents of the Mohave pl ume that are likely to
signi ficantly affect visibi ity: particles and NO?. Particles affect visi bi
ity primari ly by scattering li ght; NO? affects visibi lity by absorbing light.
Whi le a ful discussion of the effects on vi sibil ity of both particles and NO?in the Mohave plume is deferred to Section 6, certain preliminary analyses,
interesting in their own right, are discussed in this section. The most
straightforward of these is NO-to-NO? conversion, which is discussed fi rst.
Hi gh temperature combustion processes, such as those that occur in the
boilers of coal-fi red power plants, produce negl igible amounts of NO? compared
to NO. However, in the stack from such plants, and especial ly just after exit
from the stack the NO in the effluent gases can be rapidly converted to NO? by
the reaction:
2 NO + 0^ - 2 NO? (1
This reaction can convert between 5 and 10% of the effl uent NO to NO? in the
stack and another 5 to 10% after exit from the stack and before di lution in the
atmosphere has quenched the reaction (Melo, 1977). The significance of this
-70-
mechanism as a source of NO,, n the Mohave plume 1s apparent from the NO and
NOg data isted in Table 4.2. It can be seen that roughly 35% of the NO in the
plume is in the form of NO?, even at the closest distance from the pl ant at
which measurements were made (0.46 km). At such short ranges from the stack,
the dominant NO-to-NO? conversion mechanism is most ikely Eq. (1 ). It is cer-
tai nly not the reaction:
NO + 0^ - NO? + O? (2
which pl ays such an important role in the conversion of NO to N0^ at greater
ranges from the stack (Hegg et_a1_. 1977). However, Eq. (2) is no doubt the
dominant NO-to -NO? conversion mechanism beyond the range of our closest
measurements to the Mohave plant, and it is through this reaction that most of
the NO in the pl ume is converted to NO,,.
The extent of NO-to-NO? conversion in the Mohave plume as a function of
travel time can be seen in Fig. 5.13, where the ratios of the average values of
NO/NO^ are pl otted against travel time for the five fl ights that were subjected
to detai led analyses. The curves do not suggest an exponential decay of NO, as
would be expected from chemical kinetics. The rates of NO-to-NO? conversion
(which can be cal culated from the ratios shown in Fig. 5.13) vary from ~30%
hr close to the stack to vi rtually zero at travel times beyond 6 hrs. (It
should be noted that the several increases in the average value of NO/NO with
travel time shown in Fi g. 5.13 are physical ly meaningl ess and reflect uncer-
tainties in the measurements. These conversion rates are far below those
<
x0z\0
4 5 6TRAVEL TIME (HOURS)
8 9 10
Figure 5.13 Average values (over all altitudes at each range) of NO/NOx in the Mohave plume as a function oftravel time from the Mohave stack. The number on each line is the UW flight number.
-72-
predi cted by Eq. (2) empl oying ambient 0, levels. This suggests that the con-
version of NO-to-NO^ is limited by diffusion, as we have found to be the case in
other power plant plumes (Hegg et_a_L 1977; Hegg and Hobbs, 1983). Indeed, such
a conclusion fol lows from the depletion of ozone in the plume (see Table 4.2).
5.3 Light Absorption by Particles in the Plume
Until recently it was general ly assumed that absorption of light by
particles in the atmosphere was negl igible. However, the discovery that elemen-
tal carbon can comprise a significant fraction of the particulate mass in both
urban (Countess et a1 1980) and rural (Wolff and Kl imisch, 1982) ai r has
resulted in a reevaluation of the significance of the role of particles in the
absorption of light. Such absorption has been observed even in very remote
ocati ons (Waggoner et a1 1981, Heintzenberg, 1982) far from the sources of
anthropogenic carbon. It is possible that coal-fi red power plants, such as
Mohave, wi emit carbon particles with significant light-absorption coef-
ficients relative to those of the ambient air. To assess this possibi lity, some
panicul ate fi lter sampl es were taken during the 1980 field study. These were
subsequently analyzed to determine the light-absorption coefficient of the par-
ticles on the fi lters. The results of the analyses are shown in Table 4.4.
While the values of particle light-absorption coefficient shown in Table
4.4 are substantial there does not appear to be any systematic difference bet-
ween the values measured in the ambient ai r and in the plume. Indeed, the
highest values were measured in ambient air. It is conceivable that the ambient
values are unusual ly high due to the occurrence of several large brush fi res in the
-73-
region during the 1980 study period (Hobbs et_a]_. 1982). Nevertheless, on the
basis of this prel iminary data, the Mohave plume does not appear to be a signi-
fi cant regional source of ight-absorbing particles. Furthermore, comparison of
the values of the particle light-absorption coefficients measured in the Mohave
plume (see Table 4.4) with the measured light-scattering coefficients (see
Table 4.2) reveal that the ight-scattering was far greater than the light
absorption. It therefore appears reasonable to concentrate on particle light
scattering in evaluating the effects on vi sibil ity of the particle emissions
from the Mohave plant.
5.4 Particle Size Distributions in the Plume
Assuming that light absorption by particles is not significantly elevated
in the Mohave pl ume, the proximate cause of any visibil ity impact due to par-
ticles in the Mohave plume woul d have to be particulate light scattering, which
s a strong function of the particle size distribution. Furthermore, several
other interesting questions, such as the rates of gas-to-particle conversion,
are strongly influenced by particle size di stributions. Hence, we turn now
to the shape and evolution of the particle size distributions in the Mohave
plume.
Representative particle numbers, surface and volume distributions in the
Mohave plume are shown in Fi g. 5.14. These particular distributions were
measured at a range of 0.46 km from the Mohave stack on 27 August 1979. It can
be seen that the particle number concentrations in the plume are general ly more
90-4
&56
-3
102
iA
48
^ 40SU
C\J
S 32-
^3-
Q
24
ino<Po^
16
80
70
60
if!"
"? 50
Q 4000_1
>?-o
20
103 Q
i62 10’ 10 10’ 10PARTICLE DIAMETER (urn)
2 0- ft^’^^tooia.010 10 10
PARTICLE DIAMETER (wn)10
(a) (b)Figure 5. 14 Particle number (a), surface (b), and volume (c)distributions In the Mohove Plume (triangles) and In the ambientair (squares) at an altitude of 0.76 km, end 46 km from the planton UW Flight 606, on 27 August 1979. Plume measurements wereobtained with a modified Rogco 202. Ambient measurementswere obtained with both a Rogco 202 (upper curve) and a Royco225 (lower curve).
oi62
’Anrar&oi.0
-n-10’ 10" 10’ 102
PARTICLE DIAMETER urn )
( C )
-75-
than an order of magnitude greater than those in the ambient ai r. In the opti-
cal ly-critical size range, from 0.3 to 1.5 \im diameter (which brackets the first
Mie scattering peak for visible wavelengths) the difference is even larger,
close to two orders of magnitude. This large discrepancy, or mode, is seen more
clearly in the surface and volume distributions, also shown in Fig. 5.14.
Indeed, these higher moment di stributions reveal that the submi cron particle
size distribution is actual ly bimodal having surface and volume peaks at ~0.5
and 1.0 urn di ameter, with the 1.0 urn peak being the larger of the two.
As the plume ages and the primary particles are transported downwind and
mix with the ambient air, the particle number concentrations are much reduced
relative to the ambient ai r, and the shapes of the particle size distributions
change somewhat. For example. Fig. 5.15 shows the particle number and surface
distributions in the pl ume on 27 August 1979 at a range of 27.8 km downwind of
the Mohave pl ant. While sti of the same general shape as the distribution at
0.46 km (Fi g. 5.14) the relative sizes of the modes at ~0.5 and 1.0 urn di ameter
are changed, with the 0.5 pm mode becoming more comparable to the 1.0 urn mode.
At a range of 92.6 km (Fig. 5.16) the plume and ambient particle number con-
centrations were quite simi lar, except near 0.5 and 3.0 pm. The latter peak
i s probably due to local windblown dust, since it is not present at a range of
138.9 km (Fig. 5.17). Indeed, at the latter range the particle number con-
centrations in the pl ume and ambient ai r are vi rtual ly identical
/6-
10
10
10
Q. W.0
o0
10
,0^
103 010 10 10 10
PARTICLE DIAMETER [urn )t0 K) 10PARTICLE DIAMETER <^r
( a ) ( b)
Figure 5. 1 5 Particle number (e) and surface (b) distributions Inthe Moneys plume (triangiss) end In the ambient eir (squares) etan altitude of 0.79 km, end 27.8 km from the plant on UW Flight806, on 27 August 1979. Plume measurements were obtainedwith e modified Rouco 202. Ambient meesurements wereobtained with both e Royce 202 (upper curve) end e Rouco 225(lower curve).
-77-
200
&
180
O3
.(A
-o-3,
120K)
5u~ 1006^Q
u 80-0
J?60
40
104
-210
0-1 0 2
10 1(7 10 10PARTICLE DIAMETER ^w)
A.id2 io-1 id3
PARTICLE DIAMETER10’
(i/w)
(a ) ( b)
Figure 5. 16 Particle number (e) end surface (b) distributions inthe Moheve Plume (triangles) end In the ambient eir (squares) etan altitude of 0.94 km, end 92.6 km from the plant on UW Flight806, on 27 August 1979. Plume measurements were obtainedwith e modified Royco 202. Ambient measurements wereobtained with both a Royco 202 (upper curve) and a Royco 225(lower curve).
-78-
.510
10^ &
10^
lo2.!
10-’ 4
-210
1*1
U<M
Q
00
<^0
120
100
80
60
40
20
A
103
102 -I 010 10 10
PARTICLE DIAMETER t^m)
(a )
210
0 0^-2 -I 010 10 10 10
PARTICLE DIAMETER (^m
( b)Figure 5. 1 7 Particle number (a) and surface (b) distributions inthe Moheve Plume (trteng1e) end In the ambient air (squares) atan altitude of 0.94 km, end 1 38.9 km from the plant on UW Flight006, on 27 August 1979. Plume meesuremente were obtainedwith e modlflsd Royco 202. Ambient measurements wereobtained with both e Royco 202 (upper curve) end a Royco 225(lower curve).
-79-
Most of our studies of the Mohave plume have been in the summer months.
Indeed, this is true of most studies of power plant plumes. It is therefore of
interest to examine one of our winter fl ights at Mohave and compare the particle
size di stributions in the pl ume with those measured during the summer. Particle
size di stribution measured on 20 December 1978 in the Mohave plume are shown in
Fig. 5.18-5.20. The near-field size di stribution (Fig. 5. 18) is quite simi lar
to those measured during the summer, although the 1.0 pm mode is more prominent.
Figs. 5.19 and 5.20 reveal that this is the region of the particle size distri-
bution most elevated above ambient, even at considerable di stances from the
stack. As in the summer, however, the most significant feature is that the
greatest deviation from the ambient particle concentrations in the Mohave pl ume
occurs in the submicron particle size range. Since, as previously mentioned,
thi s region corresponds roughly to the optically-critical size range, light-
scattering by particles in the plume probably has a substantial effect on
regional vi siblity. Furthermore, since the particle surface area is at a maxi-
mum in this size range, low vapor pressure products of gas-phase reactions (such
as H?SO. and HNO- might be expected to condense onto particles in this size
range (i .e. gas-to-particle conversion shoul d be most marked in this size
range) Since gas-to-particle conversion has the potential to modify the par-
ticle size distribution in such a manner as to enhance particle scattering, we
wi next examine the sul fate and nitrate chemistry of the Mohave plume.
5.5 Sulfate and Nitrate in the Plume
Both sul fate and nitrate have been identified as gas-to-partic1e conver-
sion products in power plant plumes (Hegg and Hobbs, 1980, 1983). To date no
-80-
40-
’"i A
A
103
102
10
^ 10U
Q
<5 -I0 10
102
10-^
24-
ro~’’Su
^6 20
ao3 16
(^A
10410 10 10 10’
PARTICLE DIAMETER (^w
210
oi62
1^10 10 |01PARTICLE DIAMETER t urn}
( a ) ( b)
Figure 5. 1 0 Particle number (a) and surface (b) distributions In""’ ^T {’\tt^ <t^1n’"M> "’ <" th "bfent ar (squares) at"^’.^O^0;^^^ 0-93 kln from the plant 0 uw "’^
81-
o
20
.O^0
,03A
ro
.0-^
’2 12-u
cu
Q 10
o0
(^ 8-0
10-4
id2 -I 010 10 10
PARTICLE DIAMETER (x/m)
0--2 0
10 10 10 10PARTICLE DIAMETER jam)
( a ) ( b )
4Fjlgu^8 5’ 1 9 pa^t1cl9 numb8r (a) and ’"rrace (b) distributions inthe Mohove P ume (triangles) and In the ambient air (squares) at^m1tu^nof 46 km- and 46 3 km rrom the P’"t on UW FHoht725, on 20 December 1 978. rugni
-82-
18-
16-
02.
0
d0
12-M’su
C\j
I 10
Q
0
3 8-1
<^
0. a0 a0 210 10 10
PARTICLE DIAMETER (urn)
(a )
id’ 010 10 10
PARTICLE DIAMETER (um)( b)
2
t^0"^5’20 ^"018 number (<l) ttnd ^^^e (b) distributions InS^^M^^r;;:^^^Flight 725, on 20 Dscsmber 1 978.
-83-
other species have been so identified, athough it has been suggested that
organic polymers may condense under some conditions. As a fi rst step in eva-
luating the significance of sul fate and nitrate in the Mohave plume, par-
ticularly with regard to the effects of thei r production on the shape of the
particle size distribution, the contribution of these species to the total par-
ticle volume wi be presented. This information can be obtained by taking the
sul fate and nitrate mass concentrations (l isted in Table 4. 3) and converting
them to equival ent parti cle volumes. In doing this we have assumed that the
sul fate and nitrate are present as ammonium sul fate and ammonium nitrate.
Total particle volumes for the various sampl ng interval s were computed from the
measured particle size distributions.
The results of these cal cul ations are shown in Table 5.1. Several
interesting features emerge from this table. For example, the percentage
contribution of sulfate to the total particle volume is quite variable and at
times quite substantial values range from 0. 19 to 43.9%. Interestingly, the
highest value was found in ambient ai r. Indeed, the percentage contributions of
sul fate are general ly lower in the pl ume close to the stack than in the ambient
ai r, but they rise above ambient values farther downwind. This is, no doubt,
due, in part, to sedimentation of large fly-ash particles. Si nce the percentage
contributions of sul fate in the plume rise to values above ambient, sul fate pro-
duction must have been taking pl ace in the pl ume on a fai rly regul ar basis.
Table 5.1 Percentage. Contributions of SuKate and Nitrate to the Total Particle Volume in the Mohave Plume
and In the Ambient Ai r.
UW H inumber
725
725
725
806
806
806
806
807
807
807
807
807
809
809
ght
20
20
20
27
27
27
27
28
28
28
28
28
31
31
Dat
Decembi
Decembi
Decembi
August
August
August
August
August
August
August
August
August
August
August
e
er 197
?r 197
ir 197
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
1979
Range fromstack(km)
8 9.3
8 46.3
8 Ambient ai r
5.6
27.8
92.6
Ambient ai r
5.6
27.8
55.6
92.6
Ambient air
5.6
11. 1
[SO;](ug m" )
0.63
0. 96
0. 79
0.92
0.36
0.89
0.22
0.69
0.39
0.20
0.39
0.37
1. 19
0.63
[NOg](ug m~ )
0.47
0.28
0.35
0.00
0.06
0.00
0.02
0 0
0.04
0.01
0 0
0.0
0. 13
0. 12
Total particlevolume
3 -3,(urn cm
4. 16
1.55
0.64
265.41
50.27
59. 19
36.28
154. 12
13.66
7.20
8.54
20.88
82.58
31.55
Percentin totepartici
8.
34.
43.
0.
0.
0.
0.
0.
1.
1.
2.
0.
0.80
1.
;age [SO.>1e volume
4
4
9
19
,40
83
34
25
59
54
5
98
11
] Percentage [NO,]in total J
particle volume
6.6
16.5
20.6
0
0.07
0
0.03
0
0. 17
0.08
0
0
0.09
0.22
Continued
Table 5.1 (Continued) Percentage Contributions of SuKate and Nitrate to the Total Particle Volume in the
Mohave Plume and in the Ambient Ai r.
UW f1number
809
809
921
921
921
924
924
924
ght
31
31
7
7
7
11
11
11
Date
August
August
August
August
August
August
August
August
1979
1979
1980
1980
1980
1980
1980
1980
Range fromstack(km)
25.9
Ambient ai r
5.6
37.0
Ambient ai r
5.6
5.6
37.0
[SO;;](ug m"3)
0.71
0.05
4. 18
3.49
3.26
1. 19
3.25
3.22
[NOg](ug m"
0. 13
0.01
2.04
0.85
0.99
0. 13
-0-
-0-
Total particlevolume
3 -3,(urn cm
8.00*14.37
15.93
6. 10
6.85
82.58
17.53
6.01
Percentage [SO.in totalparticle volume
4.93
0.19
14.57
31.78’26.46
0.80
10.30
29.74
] Percentage [NO"]in total J
particle volume
0.96
0.04
7.53
8.1900
8.51 Y1
0.09
0
0
* Note: the total particle volume in the plume at this range is less than in the ambient ai r. Thus, the
percentage contributions of [SO.] and [NO,] may be unrepresentative of the plume as a whole.
-86-
In the case of nitrates the situation is somewhat di fferent. The
percentage contri butions to the particle volume from nitrate (0-20.6%) are
substantial ly lower than for sul fate. Once again, the highest contribution
occurs in ambient ai r. However, the evidence for nitrate production is not as
clear cut as for sul fate. Only three of the six cases shown in Table 5.1 pro-
vide evidence of above ambient nitrate concentrations in the plume. The rela-
tive lack of particulate nitrate formation, compared to particulate sul fate, is
in accord with previous studies (Ri chards et a1 1981; Hegg and Hobbs, 1983)
and is at least partial ly expl cable by the fact that much of the nitrate formed
in power pl ant plumes remains in the gas phase (as HNO~), whereas, most
H^SO. condenses (presumably as partial ly neutral ized sul fate).
The above analysi s suggests that whi le sul fate can occasional ly make
substantial contri butions to the particle volume in a pl ume, it general ly
constitutes only a smal fraction of that volume. One woul d therefore expect
that it would general ly have ittle influence on the particle size distribution,
or on the light scattering due to particles. However, if al of the sul fate
were concentrated in the optical ly-critical (i .e. submicron) size range it would
have a greater impact on light scattering. To evaluate this possibi lity, we now
examine the size distributions of sul fate particles in the Mohave plume and com-
pare them with the total particle size distribution.
Due to the long sampl ing times required to determine the size distri bution
of sul fate particles, such samples were general ly not taken on the same fl ights
as those on whi ch total sul fate was determined by fi ltration. Furthermore,
-87-
sul fate particle size di stributions were only measured during the 1980 Mohave
field study. The size distributions that are avai lable, derived from the data
shown in Table 4.6 under the reasonable assumption that a1 of the particul ate
sul fur is present as sul fate, are shown in Fig. 5.21. Since the sample times
associated with these distributions bracket those associated with the fl ights
shown in Table 5.1 it seems reasonable to assume they are representative of the
distri butions present during these fl ights. It can be seen that for six of the
seven impactor sampl es, the sul fate concentration peaked in the optical ly-
critical si ze range (0.3-1.5 urn diameter) While this is in accord with
general ly accepted ideas (Whitby, 1978) it does not necessari ly mean that
sul fate particles wi have a pronounced effect on light scattering. For
example, it can be seen from Fig. 5.21 that the percentage of sul fate that is in
the optical ly-critical size range varies from 27-631. These percentages are
much lower than expected. Coupled with the fact that a comparable or higher
fraction of the total particle volume resides in the optical ly-critical size
range, these percentages suggest that the relative concentration of sul fate does
"ot occur in this range (i .e. the percentage of particle volume that is sul fate
is no higher here than in any other size ranges). Thus one can estimate, a least
for the Mohave plume, the effects of sul fate on light scattering from the data
on the percentage contributions of [SO,] to the total particle volume listed in
Table 5. 1. This is lustrated graphically in Figs. 5.22 and 5.23, where a com-
pari son is made between measured sulfate and total particle volume
distributions. It can be seen that sul fate represents only a small fraction of
the total particle volume in the optical ly-critical size range.
0
0>
=t
0
^Q:Ld0Z0u
<
Z3(/)
0 0.49 1.05 230 4.60
PARTICLE DIAMETER (/im)
PARTICLE DIAMETER (^.m)?!91 ^^ ^rS10"1^? ^1 ?a^ ^?ce?t^tions 1n the P1"1"6 from the "Q^ve power plant on (a) 22 Jul y1 . ^ \ e stack (b) 25 July 1980 at ll l-18.5 km from the stack (c) 7 August 1980 at 12 0 kml^^ll I S^LT ^ 1?-0 ’"; ^"’i^6 stack (e) 10 August 1980 at 13<0 ^ ^om the a k (^1980 at 18.5 km from the stack and (g) 15 August 1980 at 11.1 km from the stack.
-89-
0.45 2.3 4.65 8
LARGEST PARTICLE DIAMETER FOR EACH_FILTER (urn)
Figure 5.22 Sulfate and total particle volume distributionsmeasured In the Mohave plume at a range of 1 1 1 3 km on 10August 1960.
-90-
Kl
5uroEa
LU23-I0>
UJ
1-<_j
=>23u
0 0.45 2.3 4.65 8
LARGEST PARTICLE DIAMETER FOR EACH FILTER (urn)
Figure 5.23 Sulfate and total particle volume size distributions measured in theMohave plume at a range of 11 km on 15 August 1980.""-^"rea in me
-91-
To summarize, our evaluation of sul fate size distributions and the
effects of sul fate and nitrate on the total particle size di stribution, in
the Mohave pl ume indi cate that nitrate has very little effect and that sul fate
has the potential to occasional ly have an effect on vi si bi ity degradation by
the plume.
From the above analysi s, one woul d expect the actual conversion rates of
both SO^-to-SO^ and NO^-to-NO^ in the Mohave plume to be smal with the former
somewhat higher than the latter. The limited data avai lable on conversion rates
are shown in Table 5.2. The methodology employed to derive these rates from the
data presented in Tables 4.2 and 4.3 has been described by Hegg and Hobbs (1980.1983). Cases for which both the nitrate and sul fate production rates were zero
(four cases) or for which there was insufficient data to al low either rate to
be determined (three cases) are not included in Table 5.2. In the case of
sul fate, the error in the rates is estimated to be +/-751. Due to large uncer-
tainties in the N0^ concentrations associated with the NO- concentration, the
NO^-to-NO^ conversion rates are order of magnitude estimates.
The conversion rate data exhibit several interesting features. Fi rstly,
as hypothesized, the SO^-to-SO^ conversion rate is, on average, somewhat greater
than the NO^-to-NO^ conversion rate. However, there is great variabi lity in the
relative rates, and at times the NO^-to-NO^ rate is greater than the SO -to-SO" rate.Secondly, whereas the sul fate rates show a tendency to increase with travel
time, the nitrate rates exhibit the opposite tendency. Although this suggests
that the N0^ s oxidized before the SO^ by OH radicals in the plume, care must
-92-
TABLE 5.2 Gas-to-particle Conversion Rates in the Mohave Plume
UM fl ightnumber
710
725
804
806
806
807
807
808
808
809
809
810
909
921
923
923
Mean rates
Date
4 December 1978
20 December 1978
24 August 1979
27 August 1979
27 August 1979
28 August 1979
28 August 1979
29 August 1979
29 August 1979
31 August 1979
31 August 1979
3 September 1979
24 July 1980
7 August 1980
10 August 1982
10 August 1982
Range interval(km)
rate
9-68-
9-46
7-28
6-28
28-93
6-28
28-56
6-28
28-56
6-11
11-26
6-26
6-23
6-37
6-11
11-37
SO.-to-SO"
conversion
(1 per hour)
0.5
0.4
0.05
-0-
0.07
-0-
-0-
0.06
0.1
0.3
0.6
0.01
9
0.003
-0-
-0-
0.6912.2
>0. 7
0.009
0.4
0.3
0.6
*
NO?-to-NOconversio
rate (1 per
-0-
0.01
-0-
0.05
-0---0--0-
-0-
-0-
-0-
0.14+/-0.24
3
n
hour)
* +/-751+ Order of magnitude estimate
Insufficient data to calcul ate
-93-
be taken here. The rates shown are for conversion of NO? to particulate NO,.
It has been shown (Ri chards et a1 1981 Hegg and Hobbs, 1983) that much of the
NO. in power plant pl umes can be in the form of gaseous HNO, (the di rect oxida-
tion product of NO,). The extent to which HNO, condenses to form pani cul ate
N0^ wi depend on such variables as avai lable NH, and relative humidity. In
short, the production or particulate NO, is not as di rect a function of the OH
oxidation reaction as is particulate sul fate. Unfortunately, no measurements of
gaseous HNO, have been obtained during any of our field studies at Mohave.
Si nce HNO, depositions may be the major sink for odd-nitrogen in power plant
plumes (Ri chards, 1983) future studies at Mohave shoul d include HNO, measurements,
Another interesting point raised by Ri chards (1983) is that oxi dation
of N0^ to N0^ (total NO- in pl umes should be faster than the conversion of
SO.-to-SO. and that dry deposition of HNO, is general ly faster than dry deposi-
tion of sul fate particles. It is therefore pl ausi ble that odd-nitrogen is
removed from power plant pl umes appreciably faster than sul fur, and that the
regional impact of odd-nitrogen emissions may be on a considerably smal ler spa-
tial scale than the sul fur emissions. Whi le the data to di rectly assess this
possi bi ity are not in hand, a preliminary evaluation can be made on the basis
of the relative rates of decrease of SO, and NO in the Mohave plume.
Examination of the NO /SO, ratio and its variabi ity with travel time providesA
this information.
-94-
The relevant data are shown in Table 5.3. Whi le these data provide some
support for the idea of preferential deposition of odd nitrogen, the overal
data set is ambiguous on this point. For example, whi le the NO /SO ratio
general ly decreases between the fi rst few successive ranges from the plant on
any given fl ight, the value of this ratio at the ast range measured is always
elevated above that at the range immediately prior to it. Furthermore, on 11
August 1980 the NO^/SO? ratio systematical ly increased with travel time. In
contrast to the scenario presented by Ri chards (1983) it is conceivable that
both SO? and NO? are converted only slowly to their conversion products and that
what is observed is the depletion of SO? and NO by di rect deposition. Since
the deposition velocity of NO? (and NO) is substantially less than that of SO,,
(Sehmel 1980) observations such as those in Table 5.3 are expl cable. A com-
bination of the two scenarios described above could also prevai For exampl e, the
sink for sul fur may be SO? deposition, whi le for NO it could be conversion to
HNO^ and then deposition of HNO-. The "mix" of possi ble loss mechanisms woul d
then determine variations in the NO /SO? ratio with travel time in the pl ume.
Having invoked the dry deposition of SO? as a potential major sink for
SO? in the Mohave pl ume, we wi now examine briefly the magnitude of this sink
n the Mohave plume. Certainly the low SOp-to-SO. conversion rate shown in
Table 5.2 suggest that the major sink for SO? n the plume is something other
than conversion to sulfate. Si nce dry deposition of SO? s the only plausible
alternative sink we can examine it by determining the SO? loss rate from the
-95-
TABLE 5.3 Ratios of NO^/SO^ Measured -in the Mohave Plume. The Ratios are
Based on the Peak Concentrations of NO and SO,-, Measured at^
the Sped tied Ranges.
UW fl ight Date Range fromnumber stack
(km)NO^/SO^
725725725806806806806806806806807807807807807809809809809924924924924924
20 December 197820 December 197820 December 197827 August 197927 August 197927 August 197927 August 197927 August 197927 August 197927 August 197928 August 197928 August 197928 August 197928 August 197928 August 197931 August 197931 August 197931 August 197931 August 197911 August 198011 August 198011 August 198011 August 198011 August 1980
0. 99.2
46.20.465. 59.2
25.955.594.3
139.00.465.5
27.855.592.50.465.5
11. 125.90.465.5
11. 122.237.0
3.92. 12.210.4
1. 31.30.602. 12.41.71.62. 12. 73.32.31.82.50.650.820.822.24.3
-96-
Mohave plume after correcting, in principl e, for losses due to conversion to
sul fate. If the total loss rate is large compared to the conversion rate, thi s
correction may be neglected. The data shown in Table 5.2, once again, suggest
that thi s is the case, and it wi be assumed a priori to be justified by the
analysis itself.
To calcul ate the total loss rate of SO,, from the Mohave plume, the
SO? current at various ranges from the stack has been determined from area-.
weighted integration of the y-z cross sections of the plume (such as those shown
in Fig. 5.12) and the mean wind speed over the cross sections. The change in
SO,, current with range (or travel time) yields the loss rate of SO-, which we
wi assume to be due to deposition.
Currents of SOp calculated in this way are shown in Table 5.4. The values
indi cate much variabi ity, even within a particular fl ight. Indeed, in a number
of instances the current actual ly increases with range, which is a physical
impossibi ity. This merely reflects the high uncertainty associated with the
individual values (+/-301). In the three instances where adjacent current
measurements are significantly di fferent (DM Fl ight 806, 9.3-27.8 km and UW
Fl ight 924, 11. 1-22.2 and 22.2-37.1 km) the data show the expected decrease in
current with travel time. These two fl ights have been further analyzed to quan-
tify the loss rate of SO,,. This was done by assuming that the current loss is
proportional to the current itsel f:
-^- -ks <5-1
where, S is the SO? current and t the travel time. Hence,
S S^e-^ (5.2)
-97-
TABLE 5.4 Currents of S(L Measured in the Mohave Plume.
UW fl ightnumber
725725725806806806806806807807807807809809809924924924924
Date
20 December 197820 December 197820 December 197827 August 197927 August 197927 August 197927 August 197927 August 197928 August 197928 August 197928 August 197928 August 197931 August 197931 August 197931 August 197911 August 198011 August 198011 August 198011 August 1980
Range fromstack"
(km)
9.346.388.95.69.3
27.893.5138.9
5.627.855.692.65.6
11.125.95.6
11.122.237.0
Travel time(hr)
0.251.242.390.270.451.334.486.650.120.581.151.920.310.621.440.400. 791. 592.64
*SO? current
(kg s-1
0.190. 260. 322.001.860.550.550.510.761.280.841. 160.330.230.250.990.850.280.03
* Estimated to be accurate to +/-301.
-98-
Whi le there is some justi fication for such a formul ation in terms of conven-
tional definitions of the deposition velocity (which is proportional to
concentration) we set it forth here merely as a mathematical ly convenient way
to arrive at the SO^ oss rate. When the data from UW fl ights 806 and 924
(shown in Table 5.2) were regressed to Eq. 5.2 they yielded values for So
and k as fol lows: for UW fl ight 806, S 1.48 kg s"1 and k 0.19 hr"10
(r^O.58); for UW fl ight 924, S^ 2.60 kg s"1 and k 1.63 hr"1 (r^O.96). The
values for k imply pseudo, fi rst-order loss rates of 19 and 163% hr’1 and
justify our a priori neglect of SO^-to-SO" conversion in determining them.
These loss rates can readi ly be converted to conventional deposition velocities
for SO^. The results are deposition velocities of 0.66 and 9.9 cm s’i for UW
fl ights 806 and 924, respectively. Both of these depositional velocities are
reasonable, although the latter figure is somewhat hi gher than expected for
terrain such as that which surrounds the Mohave plant. However, they are sti
within a factor of two of plausible values. Therefore, it appears that dry
deposition is often the major sink of SO? in the Mohave pl ume.
5.6 Trace Constituents in the Plume
Whi le the plume constituents of primary interest from the standpoi nt of
reactivity and visual impact have now been di scussed, a limited amount of data
on several other constituents in the Mohave plume were gathered during the 1980
field study. These are di scussed briefly bel ow.
One trace constituent of possible importance in the Mohave pl ume is orga-
ni c sul fur (IV). Huang et a1 (1982) found that substantial amounts of SO? were
converted to organic sul fur (IV) in a power plant plume located in the Los
Angeles Basin. An attempt was therefore made to measure organic sul fur (IV) in
both the Mohave plume and the surrounding ambient air. Data bearing on this are
-99-
shown in Table 4.5. S(IV) was detected on only four out of eighteen fi lter
samples, and one of these was an ambient air sample. Only for the fl ights on 22
July 1980, 13 August 1980 and 15 August 1980 was S(IV) found in the Mohave pl ume
n concentrations above ambient. In each case, most of the S(IV) was inorganic
rather than organic and the maximum concentration measured was 0.14 umol m"3on 15 August 1980. This corresponds to an SO? concentration of ~3 ppb. The
mean SO^ concentration measured in the pl ume on this day at the same range was
-70 ppb. Therefore, both organic and inorganic S(IV) (other than SO. itself)are of ittle importance in the Mohave plume. It can be seen that none of the
species listed in Table 4.5 (other than sul fate) show a systematic di fference
between pl ume and ambient concentrations.
Other sources of data on trace constituents in the Mohave plume are the
cascade impactor sampl es taken during the 1980 field project. These data, which
are sted in Table 4.6, have already been employed to generate sul fate size
distribution. Of the 21 elements for which analysis was performed (Si -Se) only
a hal f-dozen or so were present in sufficiently high quantities to be
measurable, and none of these was systematical ly higher in the plume than in
the background ai r samples shown in Table 4.7. The size distri butions of the
six elements detected on 10 August 1980 are shown in Fig. 5.24 and the size
distributions of the five elements detected on 15 August 1980 are shown in
Fig. 5.25. One point of interest is the relatively high concentrations of
chlorine, mostly in the 0-0.49 urn particle size interval The size di stri bution
for chlorine suggests that it is a condensate, possibly due to chlorine produced
by the combustion of coal On the other hand, the size distribution coul d con-
ceivably be due to substantial modification of a maritime aerosol during long-
range transport.
-100-
0.9
0.7SULFUR
IRON
Y//////>^
LEAD
0.49 1.05 2.30 4.60
PARTICLE DIAMETER (/^.m)
Fig’ 5’24 f^^lTh""""1^10"’’ of six e1ements ^""red 1n the pl umethe sta^k power P1ant on 10 August 1980 at 13-0 km ^wr^ fron,
-101-
CHROMIUM
CHLORINE
0
&or
0.3
LJU
0U -^
CALCIUM IRON
0.3
0 0.49 1.05 2.30 4.60 0 0.49 1.05 2.30 4.60
PARTICLE DIAMETER (/^m)
Fig. 5.25 Particul ate concentrations of five elements measured in the pl umefrom the Mohave power plant on 15 August 1980 at 11. 1 km downwindfrom the stack.
-102-
SECTION 6
ANALYSIS OF THE FIELD DATA REGARDING VISUAL IMPACT OF THE PLUME
6. 1 Rel ationship Between b and SO. in the Plume______________scat____-r________
Having considered several aspects of the physics and chemistry of the
Mohave pl ume relevant to vi si bi ity, we now turn to di rect evaluation of the
vi sual impact of the pl ume. Whi le previous studies (Hegg and Hobbs, 1983) and
the analysis presented in the previous section suggest tnat there is little
relationship between pl ume sul fate concentration and light-scattering, we wi
consider this possibi ity because it is often assumed to be important. This can
be done by examining the correlation between b. .,. and [SO.] concentration. WeSCdL t
have done this for both the total [SO,] in the pl ume and the excess above
ambient concentrations of [SO,] in the pl ume. The data set is shown in Table 6.1.
The correlation between b and total [SO.] is r=0.69; this is a reasonably
high figure though signi ficantly below the value of r=0.87 for the Labadie
plume (Husar et a1 1978). However, if one considers the correlation
between the excess (above ambient values) of b and [SO.] in the plume,
the correlation fal ls to r=0.37. This is in accord with the analysis of the
previous section that suggests that the total particle size distribution must be
considered, rather than simply [SO.], when evaluating the visual impact of the
Mohave plume.
6.2 Relationship Between b and Total Particulate Volume in the Plumescat
Sul fate in the pl ume is not a good indicator of b because of the rela-s cat
lively smal contri butions it makes to the particle volume in the submicron size
range. We now examine our data for evidence of a relationship between the total
TABLE 6.1 Comparisons of b and [SO.] Measured in the Mohave Plume.SCdL t
UM fnumb
725725806806806807807807807809809809924924
ighter
2020272727282828283131311111
Oat
DecembtDecembtAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugust
;e
ir 1978ir 1978197919791979197919791979197919791979197919801980
Range frorstack(km)
9.346.35.6
27.892.65.6
27.855.692.65.6
11.125.95.6
37.0
n Total [SO.
(ug m"
0.63
0.920. 360.890.690.390.200.391. 190.630.713.253.22
] Excess [SO.]
-3^(ng m
<0
0. 700. 140.670.320.02<0
0.021. 140.580.66
0<0
scat
(m-1
8.5x10
1.6x105.2x104.6x107.2x104.0x103.7x103.3x107.7x105.2x104.4x101.8x101.0x10
-5
-4-5-5-5-5-5-55
-5-5-4-4
*Excess
(m-1
1.3x102.0x106.0x105.0x101. 7x10
04.7x101.4x104.0x101.6x10
"scat
-4.5-6-5(
-5-5-6-4
"Excess" refers to plume minus ambient values.
-104-
submicron particle volume in the plume and b The particle volumes ares cat
derived from the measured particle size distributions and the b valuesscat
from the data sted in Table 4.2.
The data are shown in Table 6.2. Cumul ative particle volumes are
shown for the commonly accepted optical ly-active parti cle size range
(0.3-1. 5um diameter) and al so for the size range 0.3-4.0 urn diameter in
order to test the sensitivity of any correlation to the size range employed.
Correlation coefficients between b and each of these two ranges of cumu-s cat
lative particle volume are shown in Table 6.3. The correlations are quite
good for the fi rst two fl ights but rather unimpressive overall It shoul d
also be noted that the correlation between b and the particle volumess cat
over the two size ranges do not differ significantly. For neither particle
size interval do the correlations with b differ from those listed pre-s cat
viously for b and [SO,] concentration. However, if we examine thescat
correlati on between the excess values of b and the excess cumul atives cat
parti cle volume for particles between 0.3 and 1.5 urn in diameter, the corre-
lation for the complete data set improves significantly to 0.77. This is
n marked contrast to the b ,.-[SO.] correlation, where consideration ofs cat ^
pl ume excess values caused the correlation to fal from 0.69 to 0.37.
Hence, for the Mohave pl ume, the total particle size spectrum is more impor-
tant with respect to light scattering than to the [SO,] particles alone.
TABLE 6.2 Cumulative Particle Volumes in the Mohave Plume and Corresponding Values of b
UW f1numbe
725725725725725725725806806806806806806806806806806806806806806806806806806
ightr
20202020202020272727272727272727272727272727272727
Date
December 1978December 1978December 1978December 1978December 1978December 1978December 1978August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979August 1979
Range Cui(km) vo
rai
0.929.29.29.29.29.2
Ambient air0.460.465.65.65.65.65.69.29.29.2
27.827.827.855.592.592.592.593.5
nul ative partlume in the snge 0.3-1.5 pi
/ 3 -3,(urn cm
16.80.360.551.322.981.200.273
245.1271.272.279.639.8
111.294.637.8846.9788.114.619.316.03.28.67.528.539.6
icie Cumulative particleize volume in the sizem range 0.3-4.0 \im
3 -3,(urn cm )
21.70.370.681.923.911.91
402.7457.7112.7131.264.3191.5148.657.880.4
124.124.531.428.37.35
17.314.118.017.6
"scat(in units of
10’4 m"1
2. 10^380 45-J0.360. 750 440.203.02 4C. t
1 0.0
?J.
1.61.6
1i ^0.610 971.60 47u.
0.50n ^7
0.41n 41^ *J
0 44n 44U
0.42
Continued
TABLE
uw nnurnbe
806806806806806806806806806807807807807807807807807807807807807807807807807807807807
6.2
ightT
27272727272727272728282828282828282828282828282828282828
Continu
Dat
AugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugust
ed) Cumu
e
1979197919791979197919791979197919791979197919791979197919791979197919791979197919791979197919791979197919791979
lative Particle
Range Cu(km) vo
ra
93.593.5
138.5138.5138.5138.5185.0185.0Ambient air
0.460.460.465.65.65.65.65.6
27.827.827.827.827.855.555.555.555.555.555.5
Volumes In the Moha
imulative particleilume in the sizenge 0.3-1.5 pm
/ 3 -3v(urn cm
4.858.44.554.635. 195.023.43.64.7
127.5150.5201.258.718.065.835.248.39.915. 154.592.574.052.942.362.522. 702.041.82
ve Plume and Correspon
Cumulative particlevolume in the sizerange 0.3-4.0 urn
3 -3,(urn cm
11.617.110.49.310.710.78.37.9
192.55244.1327.792.930.5103.656.777.818.18.457.444.136.385.414. 184.364.253.063.03
ding Values of b
^cat(in units of
10"4 m’1 )
0 440.460.46n 44^^n ddU. ~T^
0 440.400 39n ?^U*LJ
?1
1 7L C
\ 41 *0.500.56n 7?u. c.
0.630.67n 14U. J -t
n 14U.
0.40n i?u.^JC
0.380 370 33U
0 340.330.300.33
Continued
TABLE 6.2 (Continued) Cumulative Particle Volumes in the Mohave Plume and Corresponding Values of bscat"
UM H ighnumber
807807807807807807807809809809809809809809809809809809809809809809809809809809924924924924
it
282828282828283131313131313131313131313131313131313111111111
Date
AugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugustAugust
197919791979197919791979197919791979197919791979197919791979197919791979197919791979197919791979197919791980198019801980
Range Cun(km) vol
rar
92.592.592.592.592.592.5
Ambient ai r0.460.465.65.65.65.65.65.65.6
11.111.111.111.111. 125.925.925.925.9
Ambient ai r0.460.465.65.6
iu1ative particilume in the sizeige 0.3-1.5 pm
3 -3,(pm cm
1.891.811.821.931.871.832.46
27.076.142.313.626.713.718.124.217.915.913.912.78.717.512.441.551.792.214.00
19.73.65
11.18.00
e Cumul ative particlevolume in the sizerange 0.3-4.0 \im
3 -3(pm cm )
3.413. 793.353.373.213.20
36.611764.721.536.421.530.336.526.522.323.820.913.912.34.212.473.083.59
53.35.45
21.312.5
scat
(in units of
10"4 m"1
0.320.330.300.320.320.310.251.040.700.770.630.590.630.530.570.550.490.490.520.400.420.420.390.400.300.441.61.41.41.6
Continued
TABLE 6.2 (Continued) Cumulative Particle Volumes in the Mohave Plume and Corresponding Values of bscat-
UW fl ighnumber
924924924924924924924924924924924924924924924
t Dat
11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August11 August
198019801980198019801980198019801980198019801980198019801980
Range Cu(km) vo
ra
5.65.65.65.65.65.65.65.6
22.222.222.2373737
Ambient ai r
mulative particlelume in the sizenge 0.3-1.5 \im
3 -3,(pm cm
8.114.455.592.934.634.273. 723.492.342.352.451.862.031.862.42
Cumulative particlevolume in the sizerange 0.3-4.0 pm
/ 3 -3v(inn cm
12.16.748.244.276.666.305.475.343.553.373. 182.563.112.90
0. 70
^cat(in units of
10"4 m’1 )
1.50.961.40.981.001.601.201.500.800.801.001.001.001.00
-109-
TABLE 6.3 Correlations between b and Total Particle Volumes in the Mohavescat
Plume.
UW fl ightnumber
725
806
807
809
924
Alabovefl ights
Alabovefl ights(plumeexcessvalues)
Date
12 December 1978
27 August 1979
28 August 1979
31 August 1979
11 August 1980
Particle volume(d=J0.3-1.5 urn)
0. 99
0.93
0.98
0.63
0.62
0.64
0.77
Parti cle volume(d=0.3-4.0 urn)
0.99
0.92
0.97
0.59
0.53
0.64
-110-
6-3 Optical Depths from In-situ MeasurementsWe now consider the effects of the Mohave plume on visibi ity from di rect
airborne measurements of the optical properties of the plume. The measurementsconsist of the optical depths of the plume for both particle scattering and
N0^ absorption. The optical depths are calculated as fol lows. The optical
depth T as defined in Section 4.6. can be broken down into an extinction coef-ficient (b^) and a path length (Ax) over which the extinction coefficient .isappl cable. Thus,
T "ext Ax
Furthermore, the extinction coeffi cient can be subdivided into components forabsorption and scattering. Whi le the scattering and absorption apply to bothparticles and gas molecul es, we have seen that particle absorption in the Mohavepl ume does not di ffer from that of the ambient ai r. Since scattering by gasmolecul es (Rayl eigh scattering) is simply a function of total pressure, it alsowi not di ffer in and out of the pl ume. Hence, if we use pl ume-ambientdi fferences, we may neglect particle absorption and gas scattering. We maywrite:
^lume \ +
^ ^scat p ^cat a) Ax + ^abs p "abs ^ Ax
where, T^ and ^ are the optical depths due to scattering and absorption,
"scat pand "scat a are the P^^cle scattering coeffi cients measured in the
plume and in the ambient ai r. and b^ p and b^ ^are the N0^ absorption coef-
ficient measured in pl ume and ambient ai r. The latter two coefficients aredetermined from the mean N0^ concentrations measured in the plume and the ambientai r and the wavelength-dependent N0^ absorption, as given by Leighton (1961).
-111-
The path length Ax refers to the plume width, as determined by our b andS C^L
NOg measurements. Because the concentrations of NO. n the Mohave plume are
much greater than in the ambient ai r, we put b^ ^=0. Whi le the optical depths
for both particle scattering and N0^ absorption are listed as measured at 550 nm
(the middle of the vi sual spectrum) the nephelometer actual ly measured scat-
tering in a waveband centered at 525 nm, with half-power points of 505 and 550
nm. Assuming an Angstrom coefficient of 2, the listed values should be only
about 91 higher than those at 550 nm.
Optical depths calculated as outl ined above are shown in Table 6.4.
Several interesting points can be seen from these results. Fi rstly, the opti cal
depths due to particle scattering and NO? absorption are general ly comparable.
Hence, neither process can. in general be neglected in evaluating the impact of
the pl ume on vi sibi ity. Secondly, the optical depths are indicative of a
visual pl ume. Indeed, if the values given by Malm et a1 (1980) are employed
for minimum perceptabl e optical depth at 550 nm for both NO,, absorption and par-
ti cle scattering (0.025 in each case) then we woul d deduce that the Mohave plume
s visible to di stances of wel over 100 km from the stack. However, care must
be exercised here. The opti cal depths shown in Table 6.4 are probably only
accurate to a factor of 2 at best. Al so. the values given by Malm et a1 are
by no means universal ly accepted. In this regard we note that on the fl ight of
27 August 1979. the optical depth at 139 km was calcul ated to be 0.072, wel
above the 0.025 value given by Maim et a1 However, the aircraft crew did not
.
TABLE
UM flnumber
725
725
806
806
806
806
807
807
807
807
808
808
808
808
808
809
809
809
6.4
ght
20
20
27
27
27
27
28
28
28
28
29
29
29
29
29
31
31
31
In Situ Measun1s PerpendicuL
Date
December 1978
December 1978
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
August 1979
ements ofar to the
Time
0625
0740
0714
0750
0819
0918
0636
0650
0713
0814
0639
0650
0725
0815
0848
1120
1149
1225
Optical DepPlume Axis
Range(km)
0.92
9.2
27.8
55.6
93.5
13.9
5.6
10.2
27.8
55.6
5.5
11. 1
27.8
55.6
92.6
5.6
11.125.9
th at 550 uror the Mean
^0.219
0.048
0.064
0.014
0.038
0.030
0.054
0.027
0. 197
0.002
0.054
0.094
0.097
0.022
0.058
0.068
0.0240.013
n in the MeWi nd.
\
0.087
0.029
.050
.009
.045
.042
.005
.009
.020
.042
.018
.044
.063
.050
.096
.028
.016
.024
have Pli
0.306
0.077
.114
.023
.111
.072
.059
.036
.217
.044
.072
.138
.160
.072
.154
.096
.040
.037
ime.
"a
One pass
One pass
No TdephotometerData
The Path Length
Comments
TABLE 6.4
UW fl ightnumber909
909
923
924
924
924
924
926
926
926
926
928
928
928
928
929
929
929
929
929
(Continued) In S1Is Perpendicular
Date
24 July 1980
24 July 1980
10 August 1980
11 August 1980
11 August 1980
11 August 1980
11 August 1980
13 August 1980
13 August 1980
13 August 1980
13 August 1980
14 August 1980
14 August 1980
14 August 1980
14 August 1980
15 August 1980
15 August 1980
15 August 1980
15 August 1980
15 August 1980
itu Measuto the P
Time
1423
1457
0846
0819
0822
0940
1004
0819
0815
0920
0932
0759
0803
0814
0838
0743
0803
0808
0854
0920
rements oflume Axis or
Range(km)5.5
1.279
5.5
5.6
11. 1
22.2
37.0
5.5
11.1
37
50
5.5
11. 1
22.2
37
5.5
11. 1
22.2
37
64.8
)ptica1 Depth althe Mean Wind,
T
0.086
0. 161
0.050
0.119
0. 102
0.031
0
0.033
0.033
0. 174
0.091
0.085
0.017
0.297
0.386
0.288
0.184
0.473
0. 164
0.382
550 pm in
’a0.074
0.745
0.008
0.009
0.005
0.013
0.008
0.011
0.004
0.0006
0.0003
0.0008
0.003
0.0007
0.004
0
0.002
0.002
0.001
0.001
the Moh
0.160
0.019
0. 128
0.107
0.044
0.008
0.044
0.037
0.175
0.091
0.086
0.020
0.298
0.390
0.288
0. 186
0.475
0. 165
0.383
ave PI
"a
ume. The Path Length
Comments
not derived atgreater ranges
TS + TS based onN02 width
-114-
detect a visible pl ume on this day when viewing the pl ume perpendi cular to its
length. Final ly, although (as stated above) both NO,, absorption and particle
scavenging general ly play a role in the visual impact of the plume, the role of
NOp absorption vis a vis particle scavenging was much more pronounced during the
1978 and 1979 field studies than it was in 1980. Indeed, the data in Table 6.4
suggest that NO? absorption contributed negl igibly to the visual impact of the
plume during the 1980 study period. We attribute this to the lower NO,,
concentrations in the plume during the 1980 field study. The reason for the
lower NO? concentrations is unknown.
6.4 Comparison of Optical Depths of the Plume Derived from In-Situ Measurements
and Measured with a Telephotometer
During the course of the 1979 and 1980 field studies, preliminary attempts
were made to compare the optical depth of the Mohave pl ume derived from in situ
measurements in the plume with optical depths derived from telephotometer
measurements taken from the ground made at about the same time as the ai rborne
measurements. Unfortunately, these attempts were largely unsuccessful for the
fol lowing reasons. Fi rstly, the telephotometer almost never was pointed through
the pl ume perpendi cular to the plume axis (i .e. along the ai rcraft sampl ing
paths) This not only makes any comparison questionable, it makes it di ffi cult
to determine the range from the stack to be associated with a telephotometer
readi ng. Secondly, the telephotometer sites, located on the west shore of Lake
Mohave, were too often di rectly below the plume. Thus, telephotometer sightings
-115-
were frequently made through only a portion of the plume. It is di ffi cult to
establ ish a reference or "sky" value when the plume is overhead. Certainly,
such viewpaths are dramatical ly di fferent from the horizontal traverses of the
plume made by ai rcraft. Final ly, the In situ aircraft measurements and telepho-
tometer sightings were not made at the same time and at the same range.
Comparison between the two sets of derived values of the optical depth are
shown in Table 6.5. While there are a few cases where the optical depths
derived from the in situ ai rborne measurements and the telephotometer are in
good agreement, the overal agreement between the two measurements is quite
poor. Thi s is no doubt due, in part at least, to the reasons listed above.
TABLE 6.5 Comparisons of the Optical Depths of the Mohave Plume Derived fromIn Situ Ai rborne Measurements and Ground-Based Telephotometer Measurements.
UU f1 1number
806806806
807
808808
810810810
909
923
924
926
926
929
929 /
Qht
272727
28
2929
333
24
10
11
13
13
15
15
Date
August 1979August 1979August 1979
August 1979
August 1979August 1979
September 1979September 1979September 1979
July 1980
August 1980
August 1980
August 1980
August 1980
August 1980
August 1980
AiTime
085509250933
0713
06390815
0637***0747
1423
0846
0819
0819
0815
0743
0808
rborne MeasRange(km)
47.860.947.8
27.8
5.555.6
5.5***
25.9
5.5
5.5
5.6
5.5
11. 1
5.5
22.2
urements
\ + "a
0.023
0.217
0.0720.072
1.098***
0.055
0. 160
0.019
0.128
0.044
0.037
0.288
0.475
TeltTime
085509250933
0653
07400853
0807***
0933
1400
0945
0810
0800
0800
0800
0840
iphotomettRange(km)
47.860.947.8
23.0
751.6
55
21.2
4.3
6.3
6.3
6.5
9.3
6.0
20.6
*r Measurenu\
0.0170.0300.031
0.218
0.0290.478
0.0320.0300.014
0.423
0.39
0.455
0.772
0.349
0.373
0.606
?nts *6
452145
37
2744
383834
65
-35
-33
-30
4
33
79
Corn
RangesRangesRanges
Plume overhead &estimated range
Plume
Plume
Plume
Plume
Plume
**ments
uncertainuncertainuncertain
overhead
overhead
overhead
overhead
overhead
* Viewing angle of telephotometer (i .e. angle between viewpath and axis of plume).** Al comments refer to the telephotometer observations.*** No measurements were made by the B-23 at this location and time
-117-
(PAGE LEFT BLANK INTENTIONALLY)
-118-
ACKNOWLEDGMENTS
The authors wi sh to acknowl edge the ai d of M. McGuirk J. Lyons and R.
Poteet, a1 of whom assi sted in reducing and analyzi ng portions of the data
used in this report.
-119-
REFERENCES
Bol in, B. and R. J. Charl son (1976) On the role of the troposphen c sul furcycle in the short-wave radiative cl imate of the earth. Ambio, 5, 47-54.
Countess, R. J. G. T. Wol ff. and S. H. Cadle (1980) The Denver winter aerosola comprehensive chemi cal characterization. J. Ai r Po1 Control Assoc.30_, 1194-1200.
Ei tgroth, M. W. and P. V. Hobbs (1979) Evolution of parti cles in the plumes ofcoal -fi red power pl ants. II. A numeri cal model and comparisons with fieldmeasurements. Atmos. Envi ron. 13, 953-975.
Gi nam", N. V. S. Koh1 and W. E. W1 son(l98l) Gas-to-particle conversion ofsul fur in power plant pl umes. I. Parameterization of the conversion ratefor dry, moderately pol luted ambient conditions. Atmos. Envi ron. 15,2293-2314.
Hegg, 0. A. P. V. Hobbs and L. F. Radke (1976) Reaction of nitrogen oxidesozone and sul fur in power pl ant pl umes. Electric Power Research ReportEA-270, pp. 126.
*Hegg, D. A. P. V. Hobbs, L. F. Radke and H. Harrison (1977) Reactions of ozone
and nitrogen oxi des in power plant pl umes. Atmos. Envi ron. 11 521-526.
Hegg, D. A. and P. V. Hobbs (1980) Measurements of gas-to-particle conversionin the pl umes from five coal-fi red electri c power pl ants. Atmos. Envi ron._L4, 99-116.
Hegg, D. A. and P. V. Hobbs (1983) Particles and trace gases in the pl ume froma modern coal-fi red power plant in the western United States and thei reffects on light extinction. Atmos. Envi ron. 17, 357-368.
Heintzenberg, J. (1982) Si ze-segregated particul ate elemental carbon and aero-sol ight absorption at remote Arctic locations. Atmos. Envi ron. 16,2461-2469.
Hering S. V. J. L. Bowen, J. G. Wengert and L. w. Ri chards (1981)Characterization of the regional haze in the southwestern United States.Atmos. Envi ron. j_5, 1999-2010.
Hobbs P. V. L. F. Radke and E. E. Hindman (1976) An integrated ai rborne par-ticle measuring faci ity and its prel iminary use in atmospheric aerosolstudies. J. Atmos. Sci 7, 195-211.
Hobbs, P. V. C. S. Glantz, D. A. Hegg and M. W. Eitgroth (1982) A prel imi narystudy of sources of pol lution affecting regional ai r qual ity and visibi ityin the Mojave Desert and the national parks of the southwestern UnitedStates. Annual Report to the Southern Cal ifornia Edison Company from theCloud and Aerosol Research Group, University of Washington, Seattle,Washington, 98195. 123 pp.
Hotter, T. E. D. J. Mi ler and R. J. Farber (1981) A case study of visi bi lityas related to regional transport. Atmos. Envi ron. ^5_, 1935-1942.
-120-
REFERENCES (Continued)
Hoffer, T. E. D. J. Mi ner and R. J. Farber (1981) A case study of vi si bi ityas related to regional transport. Atmos. Envi ron. 15, 1935-1942.
Huang, A. A. R. J. Farber, R. L. Mahoney, D. J. Eatough, L. D. Hansen and D. W.Al lard (1982) Chemistry of invisi ble power plant pl umes in southernCa1 fornia-the ai rborne perspective. Paper 82-245, Presented at theAnnual Meeti ng of the Ameri can Chemical Society, Las Vegas, Nevada March28-Apri 2, 1982.
Husar, R. B. D. E. Patterson, L. D. Husar, N. V. Gi lani and M. E. Wi lson(1978) Sul fur budget of a power plant pl ume. Atmos. Envi ron. 12,549-568.
Leighton, P. A. (1961) Photochemistry of Ai r Pol lution. Aberdeen Press, New York,
Macias E. S. J. 0. Zwi cker and W. H. White (1981) Regional base case studiesin the southwestern U. S.--I I. Source contri butions. Atmos. Envi ron._15, 1987-1998.
Malm, W. M. Klei ne and K. Kel ly (1980) Human perception of vi sual ai r qual ity(layered haze) Conf. on Plume and Visibi ity Models and Observations,Grand Canyon, Arizona, 11-14 Novemter 1980.
Melo, 0. T. (1977) Plume chemistry studies: Nanticoke Brown Plume Study, G. S.1975. Report 77-250-K, Ontario Hydro Research Di vision, Toronto, Ontario.
Ri chards, L. W. J. A. Anderson, D. J. Blumenthal A. A. Brandt, J. A. McDonald,N. Maters E. S. Macias and P. S. Bhardwaja (1981) The chemistry, aerosolphysics, and optical properties of a western coal-fi red power plant plume.Atmos. Envi ron. 1_5, 2111-2134.
Ri chards, L. W. (1983) Comments on the oxidation of NO;? to nitrate-day andnight. Atmos. Envi ron. 17, 397-402.
Sadler, M. R. J. Charlson, H. Rosen and T. Novakov (1981) An intercomparison ofthe integrating pl ate and laser transmi ssion methods for determi nation ofaerosol absorpti on coeffi cient. Atmos. Envi ron. 1_5, 1265-1268.
Sehmel G. A. (1980) Parti cle and gas dry deposition: a review. Atmos.Environ. 14_, 983-1011.
Stevens, R. K. T. G. Dzubay. G. Russwurm and D. Ri ckel (1978) Sampl ing andanalysis of atmospheri c sul fates and related species. Atmos. Envi ron. 12,55-68.
Waggoner, A. P. R. E. Weiss, N. C. Ahlquist, D. S. Covert, S. Mi ll and R. J.Charl son (1981) Optical characteristics of atmospheric aerosol s. Atmos.Envi ron. 1^, 1891-1909.
Whitby K. T. (1978) The physi cal characteristics of sul fur aerosols. Atmos.Envi ron. \2_, 135-160.
Wol ff, G. T. and R. L. Kl imisch, eds (1982) Particulate Carbon: AtmosphericLife Cycle, Plenum Press. 500 pp.
-121-
APPENDIX A
CROSS SECTIONS OF THE MOHAVE PLUME IN THE X-Z PLANE
The fol lowi ng data were derived from ai rborne measurements taken on four of
the five fl ights for which extensive analyses is presented in this report. (The
corresponding data for the fi fth fl ight are shown in Fi g. 5. 11. ) Cross sections
along the length of the pl ume of SOp, NO and ozone concentrations and
b were constructed where data permitted.
( a ) so2
0.75
0.50’L-32
39
30
\
25
13.5
0.25
00 20 40 60 80 100
DISTANCE FROM PLANT (Km)
120
oWce^be^^^^^^^^^t^W3"the x-z }lane of he Mohave P--
( b ) ^
20 40 60
DISTANCE FROM PLANT (Km
^^^"iryW^grs^^^^^ isopleths " the x" "ane of he Mohave p’""16 on
( C ) N02
0.75
ES 0.50
UJQ3
< 0.25-^
00 20 40 60
DISTANCE FROM PLANT (Km)
ESS^Se’r^WuWgK^cTN^anny8d isopteths in the x-z plane of the Mohave P’"-"e
* >*
( d ) +/-
0.75-\
^ 0.50-1LLIa3
^ 0.25-1<
0-0 20
-r40 60 80 100
DISTANCE FROM PLANT (Km
120
Figure A.1 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plume onDecember 20. 1978 (UW Flight 725). (d) 03 in ppb.
( e ) bscAT
NEPHELOMETERNOT WORKING
-i---------r40 60
DISTANCE FROM PLANT (Km)
Figure A.1 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeDecember 20, 1978 (UW Flight 725). (e) bscat in ""’ts of 10-4 m-1. The nephelometer failed at ranges inexcess of 10 km.
(a ) so2
1.25^
E^:
UJQ3
0.75H
< 0.50^
0,25-^
00 20 40 60 80 100
DISTANCE FROM PLANT (Km
120 140
Figure A.2 Point measurements and derived isopleths in the x-z plane of the Mohave plume on August28, 1979 (UW Flight 807). (a) SO, in ppb.
( b) NO
40 60 80
DISTANCE FROM PLANT Km)
Figure A.2 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 28, 1979 (UW Flight 807). (b) NO in ppb.
(C ) N02
40 60 80DISTANCE FROM PL ANT Km
Figure A.2 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 28, 1979 (UW Flight 807). (c) NO, in ppb.
( d ) 3
16060 80 100
DISTANCE FROM PLANT Km
Figure A.2 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 28, 1979 (UW Flight 807). (d) 0, in ppb.
(e ) bscAT
0.5040.5’
0 20 40 60 80 100
DISTANCE FROM PL AN T Km
120 140 160
Figure A.2 (continued) Point measurements and isopleths in the x-z plane of the Mohave plume onAugust 28, 1979 (UW Flight 807). (e) bscat in units of 10-4 m-1.
( a) so2
0 10 20
DISTANCE FROM PLANT (Km)
Figure A.3 Point measurements and derived isopleths in the x-z plane of the Mohave plume onAugust 31, 1979 (UW Flight 809). (a) SO^ in ppb.
( b) NO
0.75
Ex.
UJQD
0.50
25
<I
0.25-^
0 -T-
10-r200 10 20 30
DISTANCE FROM PLANT (Km
Figure A.3 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 31, 1979 (UW Flight 809). (b) NO in ppb.
(C ) N02
0.75Esc
bJQ
=> 0.50
_i
<
0.25
0-1----------r0 10 20 30
DISTANCE FROM PLANT (Km)
Figure A.3 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 31, 1979 (UW Flight 809). (c) NO, in ppb.
(d ) 3
E^uQ3
0.75-^
0.50-^<
0.25-^
00 10 20 30
DI STANCE FROM PLANT (Km
^S!1’9^^o%%e^Snt^?^r?^S1ts and derived ’sopleths in the x-z plane of the Mohave plumeon August 31, 1979 (UW Flight 809). (d) 03 in ppb.
( e ) ^CAT
1.00
0.75-K
E^
0.8
0.4
^ 0.50-j3
<0.25-^
00 10 20 30
DISTANCE FROM PLANT (Km
II9^ ^? ^or!S%e/?.l?SntS^S’"’?n??nts and derived lso^et^ in the x-z plane of the Mohave plumeon August 31, 1979 (UW Flight 809). (e) bocat in ""its of 10-4 m-1.
(a) so,
.IT
ST
10 30DISTANCE FROM PLANT (Km
Figure A.4 Point measurements and derived isopleths in the x-z plane of the Mohave plume onAugust 11. 1980 (UW Flight 924). (a) SO, in ppb.
0.75-^.s500 .4io 300
0 ’0 ?0 30DISTANCE FROM PLANT (Km)
Figure A.4 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 11, 1980 (UW Flight 924). (b) NO in ppb.
(C ) N02
0.75
0.50
<
0.25
00 10 20 30
DISTANCE FROM PLANT (KmFigure A.4 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 11, 1980 (UW Flight 924). (c) NO, in ppb.
( d ) l
1015
20
10 20
DISTANCE FROM PLANT (Km
30
Figure A.4 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 11, 1980 (UW Flight 924). (d) 03 ppb.
(e ^CAT
Figure A.4 (continued) Point measurements and derived isopleths in the x-z plane of the Mohave plumeon August 11, 1980 (UW Flight 924). (e) bscat in units of 10-3 m-1.
-142-
APPENDIX B
SO^ CONCENTRATIONS IN THE Y-Z PLANE OF THE MOHAVE PLUME
The following data were derived from airborne measurements taken on four
of the five fl ights for which extensive analyses is presented in this report.
(The corresponding data for the fifth fl ight are shown in Fig. 5. 12. ) Cross
sections of SO^ concentrations at various distances downwind of the Mohave
plant are shown.
-143-
( d ) 9.3 Km
0.70-
0.60
E^uQ=) 0.50-I-
<
0.40-^
0.30-2.0 0 2.0
DISTANCE FROM CENTER OF PLUME Km
Figure B. 1 Point measurements and derived Isopleths of sulfurdioxide concentrations (In ppb) In the u-z plane of the Hohaveplume on December 20, 1 978 (UW Flight 725) at range (x) fromthe plant of (a) 9.3 km. B Indicates background concentration.
-144
( b) 46 Km
0.60-1
0.50-
0.40’
0.304.0 2.0 0 2.0
DISTANCE FROM CENTER OF PLUME Km)
4.0
F1gur B. 1 (continued) Point nrraurefnnt8 and derlvd1wp1th of ulfur dioxido concentret1on (In ppb) In th y-zplant of th Mohav p1um on DecembT 20, 1 970 (UW Flight 725)at rangt (x) from the plant of (b) 46 km. B 1nd1cat backgroundconcintrett-.
-145-
0.80i (C ) 89Km
0.70-^
E^LJ
S 0.60
<
0.50
0.404.0 2.0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km)
Figure B. 1 (continued) Point measurements and derivedIsopleths of suirur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on December 20, 1 978 (UW Flight 725)at range (x) from the plant of (c) 69 km. B Indicates backgroundconcentration.
-146-
(O ) 5.5 Km
0.70^
E. 0.65-^
uj
? 0.60-1
<
0.55-^
0.502.0 0 2.0
DISTANCE FROM CENTER OF PLUME Km
Figure B. 2 Point measurements and derived tsopleths of sulfurdioxide concentrations (In ppb) In ths y-z plane of the Mohaveplume on Auguet 28. 1 979 (UW Flight 607) at range (x) from theplant of (a) 5.5 km. B Indicates background concentration.
( b) 28 Km
a 20 B
2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km
6.0
Figure B. 2 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohove plume on August 20, 1 979 (UW Flight 807) atrange (x) from the plant of (b) 26 km. B Indicates backgroundconcentration.
(C ) 56 Km
12
4.0 2.0 0 2.0
DISTANCE FROM CENTER OF PLUME (Km)
4.0
Figure B. 2 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 20, 1 979 (UW Flight 807) atrange (x) from the plant of (c) 56 km. B Indicates backgroundconcentration.
(d) 93Km
2.0 0 2.0
DISTANCE FROM CENTER OF PLUME (Km)
4.0
Figure B. 2 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (in ppb) in the y-zpiano of the Mohove plume on August 26, 1979 (UW Flight 807) otronge (x) from the plant of (d) 93 km. B tndtcotes backgroundconcentration.
-150-
(a) 5.5 Km
0.80-^
0.75-^E^ajQ=> 0.70-1
<
0.65-^
0.602.0 0 2.0
DISTANCE FROM CENTER OF PLUME Km
Figure B. 3 Point measurements and derived tsopleths of suKurdioxide concentrations (In ppb) In the y-z plane of the Mohaveplume on August 2 1 , 1 979 (UW Flight 009) at range (x) from theplant of (a) 5.5 km. B Indicates background concentration.
151
( b ) Km
0.90-1
0.85-^
0.80-^
S 0.75-13
0.70-^
10=B
0.65^
0.60-4.0 2.0 0 2.0 4.0
DISTAN CE FROM CENTER OF PLUME (Km)
Figure B. 3 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 2 1 , 1979 (UW Flight 809) atrange (x) from the plant of (b) 1 1 km. 0 Indicates backgroundconcentration.
(C ) 26Km
0.95-^
0.90-^E^LJ
^ 0.85-j
<
0.80-^
13
0.75
0.704.0 2.0 0 2.0
DISTANCE FROM CENTER OF PLUME (Km
4.0
Figure B. 3 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 2 1 , 1 979 (UW Flight 009) atrange (x) from the plant of (c) 26 km. B Indicates backgroundconcentration.
-153-
( a) 5.5 Km
4.0 2.0 0 2.0 4.0
D STAN CE FROM CENTER OF PLUME (Km)
Figure B. 4 Point measurements and derived Isopleths of sulfurdioxide concentrations (in ppb) In the y-z plane of the Mohaveplume on August 1 1 , 1 960 (UW Flight 924) at range (x) from theplant of (a) 5.5 km. B Indicates background concentration.
( b) H Km
2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km
6. 0
Figure B. 4 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 1 1 , I 960 (UW Flight 924) atrange (x) from the plant of (b) 1 1 km. B Indicates backgroundconcentration.
( C ) 22 Km
10 is
IS 17 14 9
6.0 2.0 0 2.0
DISTAN CE FROM CENTER OF PLUME (Km
6.0
Figure B. 4 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 1 1 , i 960 (UW Flight 924) atrange (x) from the plant of (c) 22 km. B indicates backgroundconcentration.
-156-
( d ) 37 Km
0.95-i
0.9CH
E^LLJQ 0.85-1
<
0.80-^
8= 8
0.754.0 2.0 0 2.0
DI STANCE FROM CENTER OF PLUME (Km)
4.0
Figure B. 4 (continued) Point measurements and derivedIsopleths of sulfur dioxide concentrations (In ppb) In the y-zplane of the Mohave plume on August 1 1 , 1 960 (UW Flight 924) atrange (x) from the plant of (d) 37 km. D Indicates backgroundconcentration.
-157-
APPENDIX C
ABOVE AMBIENT CONCENTRATIONS OF 0.55 pm DIAMETER PARTICLES IN THE
X-Z PLANE OF THE MOHAVE PLUME
The fol lowing data were derived from the airborne measurements taken
on the five flights for which extensive analyses are presented in this report.
Cross sections along the length of the plume of the above ambient concentrations
of 0.55 pm diameter particles are shown.
0.75
0.50
E^.
LUQ3
<0.25-^
00 20 40 60 80 100
DISTANCE FROM PLANT Km
120
Figure C.1 Point measurements and derived isopleths of above ambient concentrations (in cm -3) of0.55 ^m sized particles in the x-z plane of the Mohave plume on December 20, 1978 (UW Flight 725).
,288
.363
0 20 40 60 80 100 120 140 160 180DISTANCE FROM PLANT (Km
Figure C.2 Point measurements and derived isopleths of above ambient concentrations (in cm 3) of0.55 ^m sized particles in the x-z plane of the Mohave plume on August 27, 1979 (UW Flight 806).
f <
no
10
>10
0.25 -^
00 20 40 60 80 100
DISTANCE FROM PLANT (Km
120 140
Figure C.3 Point measurements and derived isopleths of above ambient concentrations (in cm-3) of0.55 ^m sized particles in the x-z plane of the Mohave plume on August 28, 1979 (UW Flight 807).
161
1.00
0.75
E^
1448-; )-1000 500
LJ
^ 0.50-1
<
0.25-^
0’0 10 20 30
DISTANCE FROM PLANT (Km
Figure C.4 Point measurements and derived isopleths of above ambientconcentrations (in cm -3) of 0.55 j^m sized particles in the x-z plane of theMohave plume on August 31, 1979 (UW Flight 809).
-162-
1.25
E^
0.75-^47LJQ
3
-12
<
0.50
0.25 ^
00 10 20 30
DISTANCE FROM PLANT (Km)
40
Figure C.5 Point measurements and derived isopleths of above ambientconcentrations (in cm -3) of 0.55 nm sized particles in the x-z plane of theMohave plume on August 11, 1980 (UW Flight 924).
-163-
APPENDIX D
TOTAL CONCENTRATIONS OF PARTICLES IN THE Y-Z PLANE
OF THE MOHAVE PLUME
The fol lowing data were derived for airborne measurements taken on three of
the five fl ights for which extensive analyses are presented in this report.
(Insufficient measurements were avai lable from the other two fl ights from which
to construct similar plots. The total concentrations of particles in cross
sections normal to the length of the plume are shown at various distances down-
wind of the pl ant.
164-
5.5 Km
0.70
0.65-^
Ea:
^ 0.60^
_i
<0.55-^
0.50-4.0 2.0 0 2.0
DISTANCE FROM CENTER OF PLUME (Km
Figure D.1 Point measurements and derived isopleths of total particleconcentrations (in units of 103 cm’3 ) in the y-z plane of the Mohave plume onAugust 28, 1979 (UW Flight 807) at (a) 5.5 km downwind of the plant.
4
( b) 92.6 Km
1.201
E^
^ 1.10^3
<1.05-^
2.5
.954.0 2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km
6.0
Figure D.1 (continued) Point measurements and derived isopleths of total particle concentrations in unitsof 103 cm-3) in the y-z plane of the Mohave plume on August 28, 1979 (UW Flight 807) at (b) 92.6 kmdownwind of the plant.
26 Km
4.0 2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km
Figure D.2 Point measurements and derived isopleths of total particle con-centrations (in units of 103 cm-3) in the y-z plane of the Mohave plume onAugust 31, 1979 (UW Flight 809) at 26 km downwind of the plant
-167-
(d 5.5Km
0.90
0.85-^
E 0.80-j
: 0.75-t-_i
<
0.70-
0.65-
0.60-4.0 2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km
Figure D. 3 Point measurements and derived fsoplsths of totalparticle concentrations On units of 103 cm"3) in the y-z planeof the Mohave plume on August 1 1 , I960 (UW Flight 924) at (a)5.5 km. downwind of the plant.
n 4
( b) Km
1.05
1.00
0.95-^E^Id
=> 0.90^
<
0.85-^
0.80-^
4.0 2.0 0 2.0DISTANCE FROM CENTER OF PLUME (Km
4.0
Figure D.3 (continued) Point measurements and derived isopleths of total particle concentrations (inunits of 10" cm-3 ) in the y-z plane of the Mohave plume on August 11, 1980 (UW Flight 924) at (b) 11.1 kmdownwind of the plant.
o- -(C ) 22.2 Km
1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4
0.95^
0.90-^Q3
< 0.85-^
0.80-^
0.75-^
0.704.0 2.0 0 2.0 4.0
DISTANCE FROM CENTER OF PLUME (Km)
Figure D.3 (continued) Point measurements and derived isopleths of total particle concentrations (inunits of 103 cm"3) the y-z plane of the Mohave plume on August 11, 1980 (UW Flight 924) at(c) 22.2 km downwind of the plant.
(d ) 37 Km
0.9CH
^ 0.85H
LJ03t-
^ 0.80--j
<
0.75-^
0.704.0 2.0 0 2.0 4.0
DI STANCE FROM CENTER OF PLUME (Km
Figure D. 3 (continued) Point measurements and derivedIsopleths of total particle concentrations (In units of 1 03 cm"3)In the y-z plane of the Moheve plume on August 1 1 1 960 (UWFlight 924) at (d) 37 km. downwind of the plant.
-171-
APPENDIX E
PARTICLE SIZE DISTRIBUTIONS IN
THE MOHAVE PLUME
Particle number, surface area and volume distributions (similar to
those shown in Fig. 5. 14) are available for various distances downwind
of the Mohave plant and for various altitudes for most of the UW fl ights.
These data are on file with the Cloud and Aerosol Research Group, Atmospheric
Sciences Department, University of Washington.
