hydrocarbon production and photochemical ozone formation ...€¦ · hydrocarbon production and...
TRANSCRIPT
Hydrocarbon Production and Photochemical Ozone
Formation in Forest Burn Plumes
Hal Westberg Ken Sexton and Don Flyckt Washington State University Pullman Washington
The purpose 01 this paper Is 10 describe ozone production In forest
slash burn plumes Plumes from controlled fires In Ihe slate of
Washington were monitored using an Instrumented aircraft Ozone
oxides of nitrogen condensallon nuclei and visual range (nepheshy
lometer) were measured continuously on board the plane Airborne
grab samples were collected for detailed hydrocarbon analysis
The slash burn plumes were found to contain significant quanlllies
of ozone A buildup of 40-50 ppb above the ambient background
ozone concentrations was not unusual Hydrocarbon analyses reshy
vealed the presence of many photochemically reactive oleflns In the
plume HydrocarbonNO rallos were favorable lor photochemical
oxidant producllon
The controlled burning of logging slash and naturally occurshyring forest fires are known sources of several primary air polshylutants including particulates CO NO~ and gaseous hydroshycarbons Although these events are typically associated with wilderness or rural areas the well documented importance of at mospherie 1ransport procpsses for pollutant episodes has rai~(d questions concerning the potential impact of these emissions on downwind ambient air quality Of particular interest is the possible contribution of forest burning disshycharges to photochemical oxidant production during plume tran~port
The concern ahout possible adverse effecL from forest burning on nmbient air qunlity hns prompted several invesshyt igdt ions to namine this issue A nllmber of st udies have been jlublishpd on the constitutnLlt of forest fire smoke I but little data exist on oxidant production directly attrihutable to these emissions Some efforts have been made to identify individual hydrocarbon compounds from combustion of various vegeshytation types~8 however further r(search is ne(middotded in order to (middotstlhlish the dominant hydrocarbon spfcies f(~ulting from t Ill burning of forest material Sewmiddotral invpstigators have reshyport(middotd eleat(-d ozone levels measurd downwind of forest fires~-II and the ability of wood hurning to produce photoshych(middotmical 0 3 has ben demonstrated under simulated atmoshypheric conditions 12 A recent report by GEO~lET Inc ummrizes slnte-of-the-knowkdge concerning the impact (fforlst burning on air quality in ashing1on nnd Oregun 13
t the pr(middot~tnt time h()(middot(middotr iln adfquJ1t data ba~t does not middot ~ i t middothi(h would dlow a r1tinJl1Ild sci(ntific a-ot-- ment f lilt trtc(middot --ff lJtmiddottwun pr(-~crihtd L~ring of und-cirble f fl - m(middotril ann tht lfftct on amhient lir quality
VC-ne 31 r~o 6
A program was initiated in 1977 to investigate the oxidant forming potential of forest fire emissions Utilizing an inshystrumented aircraft the study is aimed at identifying oxidant precursrs in the combustion produrts and monitoring phoshytochemIcal transformations within the plume as it is transshyPrted downwind Efforts have focused on 1) identifying inshydIVIdual C~ClO molecular wright hydrocarbons 2) measuring concentratlOns of NMHC NO N02bull and 0 3 within the plume houndaries and 3) aerial monitoring of photochemical transformations (03 buildup) during plume transport
Experimental
Ambient measurements of forest fire emissions (prpscriLed burning) were made with an instrumentpd Aero Commander 680FL This high wing twin engine aircraft is capable of carrying a pilot an instrument operator Ilnd Ilpproximately 800 lb of equipment The Aero Commander was e4uipped to make continuous measurements of 0 3 NO~ S02 condensashytion nuclei visulll range (nephelometer)llnd vnrious meteoshyrological Ilnd naviglltional parllmeters In addition grab sampks were collected in stainless stel canisters Ilnd returned to the Air Rpsources laboratory at Washington State Unishyversity for individual hydrocnrhon idpntificlltion Details of the sampling Ilnd analytical procedures have I)((n reported elsCwhere 14
Results
On Octoher 25 1978 the Forest SpTin conducted a slash burn near RaId Butte in till RIll ~1()Jnt1ins of southeas(rn ashington The fire which consumlod ahout 2S acres was started in the morning at an elcJtion of npproximately middotWOO ft MSL Enstprn althing1nn was undtr the influence of a high pnSSlre ~ystcm on Octohcr 2) with denr skips and liht winds (55 mph) Grndient wind flow wns frllm the south(st with the plDme from thp burn drifting nort hpIIst(middotrly toward the twin cities ofCbrkston VA and L(middotwitonID
ircraft sampling traWL-tmiddot IIf the plume were made beshytW(en 130 and 230 in th(- afttfnoon The aircraft was equipped to make real timl mltnSlJrement of OJ ~O~ S02 c(ln~~nation nuclei and middotjllRl ran~e (Il(-phdurn(middottcr) In aodltlOn grab ~Jmples w(rf- ( (llt-eltmiddotd fur d(middott~il ( middot d horo( bon InJly~js_ The nht p_1th (( ojq(d rf (f( -- plllm-( ar dlffu(-nt tilllfll lt nt pin-~middot c middot d ~ mi d 1 l1 wind () b urn ltil(middot C(rill 1 5 gt(middotre ro 11 cl n t lll iJ dk ()
plume for distances of 15 mi In this latter case the aircraft began upwind of the burn at an altitude that would intersect the rising portion of the plume above the fire On October 25 1978 the optimum sampling altitude was 5500 ft
Figure 1 shows the changes that occurred in a number of pollutant concentrations as the plane entered the slash burn plume Ozone levels outside of the plume were about 50 ppb Immediately over the fire the 0 3concentration decreased to about 30 ppb Then as the aircraft proceeded downwind in the plume 03 levels began to increase and reached a peak of 81 ppb about 35 mi (80 sec) from the fire Oxidant concentrations in the plume decreased somewhat at greater distances from the fire however they remained above ambient background levels to 10 mi downwind of the burn
Upwind of the fire ambient NO and N02 concentrations were less than 5 ppb Both NO and N02 levels increased substantially over the fire A peak NO concentration of 29 ppb was measured 07 mi (16 sec) downwind of the burn while the N02 concentration exceeded 50 ppb 2 mi downwind of the burn and then began to decrease slowly as the emissions drifted further downwind
As would be expected particle concentrations in the plume were extremely high relative to the background air Condenshysation nuclei increased from ambient levels of approximately 400 out of the plume to over 100000 above the burn At 10 mi downyind of the fire CN levels were still in the 30000 range
90
80
70 0 c 2 60 0
50
40
-32 0 16 48 64 80 96 112 128
60
50
0 40 c 2 300 z 0 20z
10
-32 -16 0 16 32 48 64 80 96 112 128
Off scale 100000 Off sclle
8
10
80000
E z60000 - 6 u 0
400004 ~
c
2 20000
-32 -16 0 16 32 8 64 80 96 112 128 T r- l IgtltC )
Filiur1 P ht~ t corcE ~ a middot middot -C - pound ~ Bu1e stash blln plUToC ~t-~tj e 1rne is u ind of fi~e pos imiddot ~ 1$ I f) r hlne
sectsect
90
80
0 c 702 0 60
50
-48
150 c 2 100 z 0 5 z
-48 -36 -24 -12 0 12 24 36 4B 64 72
10000010
800008
E 6 60000 5
0
4 40000j 2 20000
-48 12 64 72 Time (sec)
Figure 2 Pollutant concentrations recorded in Bald Bune slash burn plume 35 miles downwind 01 the lire at 5500 It MSl
brcat values jumped from a background of about 025 to greater than 100 in the plume
Cross plume arcs were flown in the region of maximum 0 3
buildup-about 35 mi from the burn At that distance passes through the plume at 5500 and 5750 ft showed the highest pollutant levels Figure 2 shows 0 3 NO N02 and particulate changes recorded as the aircraft traversed the plume at an altitude of 5500 ft Total time in the plume as evidenced by elevated pollutant levels was about 80 ec This corresponds to a plume width of 35 mi Peak 0 3 values measured in the plume were approximately 93 ppb as compared to background levels of 48-50 ppb The highrst in-plume NO level recorded was 12 ppb with this being essenti3lly all N02 Very little evshyidence of bum emissions was observed at 5000 or 6000 f1 The plume centerline appeared to he at lIhout 5()() ft lIS indicated previollsly Thus at 35 mi from the bum site the plume was about 35 mi wideless than 1000 ft in Hrtical depth and exshyhibited an 0 3 buildup of aboutmiddotW ppb
Hydrocarbon coneent rations ohtained from samples colshylected in and out of t he plume on OctoLer 25 are shown in Table 1 It elln be seen that themiddot backgr(lund air contained less than ]4 ppbC of measurable hyoroc3rbons while tbe conshycentration of the same hydrocarbon 51(cies immediately above the fire totalled 642 pphC At th(-J oint of milximum 0 3
buildup 35 mi downwind (f the hum a horocarbon conshycentration of 142 pphC was T(- (orchmiddoto P hntJ rlllmiddot mi cally reacshytive olefins contribute significantly to the hydr(l(Tbon total ncar the burn Propene I-buttne i-buter and the cis and trans-2middotbuUnrs c()n ~ titute about 2U (f t- (middot to al 0iMHC
Due to the litht and viH j h ~ ( wi nd e (middotn Octlk r 251978 it Wl~ difficult to charact(middotri zt tr e l ltr H f ~ II1 ( h mure than 10 mi fr um the burn n rltkr infu l 1 1 ~ r b tl a llpo rt of oxio ants prfduc r-d in f01l h lTn - - lmiddot i nmiddot 0 in a ~tudy
o Table I Hydrocarbon concentrations (ppbC) measured during October 251978 slash burn
35 miles Upwind In plume downwind in 2 mi 15 mi 30 mi
of burn over burn burn plume
Total NMHC 135 642 142
Individual Species
Ethane 32 998 285 Ethylene 05 129 398 Acetylene lt05 210 62 Propane 14 311 93 Propene lt05 765 198 i-Butane lt05 23 10 n-Butane 19 89 23 I-Butene lt05 155 30 i-Butene lt05 89 15 13-Butadiene lt05 167 26t-2-Butene c-2-Butene lt05 111 14 imiddotPentane 05 56 15 n-Pentene lt05 33 10 I-Pentene lt05 45 10 n-Hexane lt05 21 12 Benzene lt05 638 108 n-Heptane lt05 24 lt05 Toluene lt05 245 33 Furfural lt05 129 lt05 Ethylbenzene lt05 24 lt05 m amppXylene lt05 45 lt05 Styrene lt05 25 lt05 a-Xylene lt05 16 lt05 Benzaldehyde lt05 16 lt05
conducted a year earlier in the fall of 1977 A much larger fire was burning north of Packwood in Washingtons Cascade Mountains on October 18 1977 This was a bright sunny day in eastern Washington with gradient winds crossing the Cascade Mountains from west to east Smoke from the Packwood burn could be seen for about 50 mi as it drifted east ward into the central part of Washington State Figure 3 shows the location of the prescribed burn and the direction of plume flow Cross-plume traverses at distances of 15 and 30 mi downwind of the burn showed a plume width of 15 and
MI Rainier A Smoke
p~ SlashG~ Burn
bull Packwood
1 1 1 0 20mi
L_-=------ Scale
1 Figure 3 Map showing the region 10lt Packwood slash burn
plume study
2 mi respcctively Vertically the plume was confined to il region uetwe(-n about 6800 and 8000 ft Figure 4 indicates maximum OJ buildup in the plume at arious points downshywind of the fire
The difference uctw(middotcn OJ concentrations in and out of the plume was aultut the ~i1me (-10 ppu) fur the Packwood emisshy~ions as that rpound(orded in the sm llc r firpound s tudied in 19-8 Ho (middoter due to the otrontu pre i ~ - b windlt (middotIlmiddotat(middotd oxishydnt Itvel5 wde rtcordd at much grt-atu di ta nn-s c owrwind
June 1981 Volume 31 No6
I -- ~-r-IPackwood - - - shyBum ~ S f-- -____ ~[
A03=55ppb shyA03 z 4Oppb A03=4Oppb
Figure 4 Schematic diagram showing ozone buildup (03) at various distances downwind of the Packwood burn
of the Packwood burn A vertical aircraft sounding 50 mi east of Packwood (downwind) showed a band of high OJ between about 7000 and 10000 ft Figure 5 shows temperature and OJ changes recorded during the vertical profile An OJ maximum of 130 ppb was observed at approximately 9000 ft While it is not possible to unambiguously ascribe the 0 3 bulge at 9000 ft to emissions from the Packwood burn it is certainly the most likely source
Discussion
Based on the data presented OJ production occurs very rapidly in slash burn plumes Often OJ has begun to accushymulate in the plume very close to the location of the burn In fact on several occasions excess OJ was observed directly above the forest burn These elevated OJ levels are the result of ample amounts of reactive hydrocarbons a favorable NOzINO ratio and sufficient sunlight to initiate and sustain photochemical reactions
Data from Figures 1 and 4 and Table II illustrated these points The HCNOx ratio in the burn plume above the fire on Octouer 251978 was 99 which is in the optimum range for photochemical oxidant formation ls Evidence for the inshyvolvement of these ozone precursor species in photochemical processes includes (I) the rapid conversion of NO to N02 as shoym in Figure 1 and (2) the preferential loss of the more photochemically reactive hydrocarbons Table 1I illustrates this latter feature by listing HC concentration changes with distance (time) The more reactive olefinic species decreased by an average factor of 56 at the point of maximum OJ buildup while the paraffins and less react ive mult iple bonded species exhibited an average concentration dlcrrase of 3t If this factor of 33 is ascribed to dilution the average olefinic change can be divided into approximntely GOr( dilution lnd 40 chemical loss
35 40 45 50 55 60 65
Temp (OF)
3L--L~__~-L__L-~__________~~
70 80 90 100 110 120130 OJ (pgtbl
FliHtt 5_ Vt--r al OlOf le --j ~j mvr a Ue ~ cf ~ C n e
OO middotn lnd oe PacJ ~ood brn
ES3
----------------------------~----------
T bJe II Hydrocarbon concentration (ppbC) changes from a References
a I In the slash burn plume directly over the burn and 35 miles pom f 0 b Iddownwind in the plume at the locatIOn 0 maximum 3 UI up 1 L Fritschen et al Slash Fire Atmospheric Pollution USDA
35 miles downwind Concentration
In plume in plume ratio over burn (03 Max) (over bum03 Max)
Ethane Ethylene Acetylene propane i-Butane
998 129
210 311
23
285 398
62 93 10
35 3_2 34 33 23
n -Butane 89 23 39 i-Pentane 56 15 37 n-Pentane 33 10 33
average 33
Propene 765 190 39 I-Butene 155 30 52 i -Butene 89 15 59 t -2-Butene 13middotButadiene
167 26 64
c-2-Butene 111 14 79 I-Pentene 45 10 45
average 56
TNMHC 642 142 45
Based on the highly reactive nature of the HC mix and the optimum HCINOz ratio it would be expected that photoshychemical oxidants would be produced rapidly and conseshyquently transport processes would involve the advection of these initially produced oxidants with little continued proshyduction as the plume drifted downwind This appears to be borne out by the ambient measurements As illustrated in Figure 4 03 levels were highest two miles downwind of the burn and then showed a dilution effect at distances further downwind
The impact of oxidants produced in slash burn plumes on downwind air quality will be highly dependent on meteorology and the elevation of the fire relative to receptor areas In both of the examples cited above plume generated oxidants reshymained aloft and therefore had a negligible effect on ground level pollutant concentrations However it is very likely that a large slash burn or uncontrolled gtildfire burning at the same elevation as a downwind receptor area could contribute sigshynificantly to surface 0 3 levels Indirect evidence for this has been reported recently in Norway where O~ levels in excess of 100 ppb were recorded during the period when a forest fire was burning 40 mi upwind of a ground level monitoring sitelI
Acknowledgment
We wish to thank the Emironmental Sciences Research Laboratory US Environm(ntal Protection Agncy for supshyporting this work
Forest and Range Experiment Station Portland OR 1970 2 D E Ward et al An Update on Particulate Emissions from
Forest Fires presented at the 69th Air Pollution Control Assoshyciation Annual Meeting Portland OR 1976
3 C Yamante Development of Emission Factors for Estimating Atmospheric Emissions from Forest Fires US Environmental Protection Agency publication EPA-4503-73-oo9 October 1973
4 C Yamante J Stockman An Inventory of Emissions for Forest Wildfires Forest Managed Burns and Agricultural Burns presented at the 68th Air Pollution Control A~sociation Meeting Boston MA 1975
5 D V Sandberg S C Pickford E F Darley Emissions from slash burning and the influence of flame retardant chemicals JAPCA 25 278 (1975)
6 E F Darley F R Burleson E H Mateer J T Middleton V P Osterli Contribution of burning of agricultural wastes to photochemical air pollution JAPCA II 685 (1966)
7 J J McElroy Agriculture and Air Pollution-Report 1959 University of California Extension Service Berkely CA 1959
8 M Feldstein S Duckworth H C Wohlers B Linsky The contribution of the open burning of land clearing debris to air pollution JAPCA 13 542 (1963)
9 L F Evans J A Weeks A_ J Eccleston D R Pockham Phoshytochemical ozone in smoke from prescribed burning of forests Environ Sci Technol II 896 (1977)
10 L F Radke J L Stith D A Hegg P V Hobbs Airborne studies of particles and gases from forest fires JAPCA 28 30 (January 1978)
11 J Schjoldager B Sivertsen J E Hanssen On occurrence of photochemical oxidants at high latitudes Atmos Environ 12 461 (1978)
12 W H Benner P Urone Photoch~mical Potential of Forest Fire Smoke pre~ented at the 70th Annual Meeting of the Air Polshylution Control Association Toronto Canada June 1977
13 Impact of Forestry Burning Upon Air Quality GEOMET Inc Report No EPA 9109-78-052 US Environmental Protection Agency 1978
14 H middotestberg K Allwine E Robinson Me3sur~ment of Light Hydrocarbons and Oxidant Transport-Houston Study 1976 Report No EPA 6003-78-062 US Environmental Protection Agency 1978
IS B Dimitriades Effects of hydrocarbons and nitro~en oxides on photochemical smog formation Environ Technol 6 253 (1972)
Dr middot(middot stherg is a faculty member in the D(partment of Chemical Engineering Air Resources S(ction at Washington State l1niversity Pullman VA 99164 Mr Sexton is in the Dlp~rtrncnt of Environmental Health Scipnces Harvard Schol of Public Health 677 Huntington Ave Roslon MA 02115 Mr Flyckt is with Dames und Moore Atmospheric S(rviccs HOllston TX 17092
J middotr31 of h c Air Pollu~ion Contr ol Association 664
plume for distances of 15 mi In this latter case the aircraft began upwind of the burn at an altitude that would intersect the rising portion of the plume above the fire On October 25 1978 the optimum sampling altitude was 5500 ft
Figure 1 shows the changes that occurred in a number of pollutant concentrations as the plane entered the slash burn plume Ozone levels outside of the plume were about 50 ppb Immediately over the fire the 0 3concentration decreased to about 30 ppb Then as the aircraft proceeded downwind in the plume 03 levels began to increase and reached a peak of 81 ppb about 35 mi (80 sec) from the fire Oxidant concentrations in the plume decreased somewhat at greater distances from the fire however they remained above ambient background levels to 10 mi downwind of the burn
Upwind of the fire ambient NO and N02 concentrations were less than 5 ppb Both NO and N02 levels increased substantially over the fire A peak NO concentration of 29 ppb was measured 07 mi (16 sec) downwind of the burn while the N02 concentration exceeded 50 ppb 2 mi downwind of the burn and then began to decrease slowly as the emissions drifted further downwind
As would be expected particle concentrations in the plume were extremely high relative to the background air Condenshysation nuclei increased from ambient levels of approximately 400 out of the plume to over 100000 above the burn At 10 mi downyind of the fire CN levels were still in the 30000 range
90
80
70 0 c 2 60 0
50
40
-32 0 16 48 64 80 96 112 128
60
50
0 40 c 2 300 z 0 20z
10
-32 -16 0 16 32 48 64 80 96 112 128
Off scale 100000 Off sclle
8
10
80000
E z60000 - 6 u 0
400004 ~
c
2 20000
-32 -16 0 16 32 8 64 80 96 112 128 T r- l IgtltC )
Filiur1 P ht~ t corcE ~ a middot middot -C - pound ~ Bu1e stash blln plUToC ~t-~tj e 1rne is u ind of fi~e pos imiddot ~ 1$ I f) r hlne
sectsect
90
80
0 c 702 0 60
50
-48
150 c 2 100 z 0 5 z
-48 -36 -24 -12 0 12 24 36 4B 64 72
10000010
800008
E 6 60000 5
0
4 40000j 2 20000
-48 12 64 72 Time (sec)
Figure 2 Pollutant concentrations recorded in Bald Bune slash burn plume 35 miles downwind 01 the lire at 5500 It MSl
brcat values jumped from a background of about 025 to greater than 100 in the plume
Cross plume arcs were flown in the region of maximum 0 3
buildup-about 35 mi from the burn At that distance passes through the plume at 5500 and 5750 ft showed the highest pollutant levels Figure 2 shows 0 3 NO N02 and particulate changes recorded as the aircraft traversed the plume at an altitude of 5500 ft Total time in the plume as evidenced by elevated pollutant levels was about 80 ec This corresponds to a plume width of 35 mi Peak 0 3 values measured in the plume were approximately 93 ppb as compared to background levels of 48-50 ppb The highrst in-plume NO level recorded was 12 ppb with this being essenti3lly all N02 Very little evshyidence of bum emissions was observed at 5000 or 6000 f1 The plume centerline appeared to he at lIhout 5()() ft lIS indicated previollsly Thus at 35 mi from the bum site the plume was about 35 mi wideless than 1000 ft in Hrtical depth and exshyhibited an 0 3 buildup of aboutmiddotW ppb
Hydrocarbon coneent rations ohtained from samples colshylected in and out of t he plume on OctoLer 25 are shown in Table 1 It elln be seen that themiddot backgr(lund air contained less than ]4 ppbC of measurable hyoroc3rbons while tbe conshycentration of the same hydrocarbon 51(cies immediately above the fire totalled 642 pphC At th(-J oint of milximum 0 3
buildup 35 mi downwind (f the hum a horocarbon conshycentration of 142 pphC was T(- (orchmiddoto P hntJ rlllmiddot mi cally reacshytive olefins contribute significantly to the hydr(l(Tbon total ncar the burn Propene I-buttne i-buter and the cis and trans-2middotbuUnrs c()n ~ titute about 2U (f t- (middot to al 0iMHC
Due to the litht and viH j h ~ ( wi nd e (middotn Octlk r 251978 it Wl~ difficult to charact(middotri zt tr e l ltr H f ~ II1 ( h mure than 10 mi fr um the burn n rltkr infu l 1 1 ~ r b tl a llpo rt of oxio ants prfduc r-d in f01l h lTn - - lmiddot i nmiddot 0 in a ~tudy
o Table I Hydrocarbon concentrations (ppbC) measured during October 251978 slash burn
35 miles Upwind In plume downwind in 2 mi 15 mi 30 mi
of burn over burn burn plume
Total NMHC 135 642 142
Individual Species
Ethane 32 998 285 Ethylene 05 129 398 Acetylene lt05 210 62 Propane 14 311 93 Propene lt05 765 198 i-Butane lt05 23 10 n-Butane 19 89 23 I-Butene lt05 155 30 i-Butene lt05 89 15 13-Butadiene lt05 167 26t-2-Butene c-2-Butene lt05 111 14 imiddotPentane 05 56 15 n-Pentene lt05 33 10 I-Pentene lt05 45 10 n-Hexane lt05 21 12 Benzene lt05 638 108 n-Heptane lt05 24 lt05 Toluene lt05 245 33 Furfural lt05 129 lt05 Ethylbenzene lt05 24 lt05 m amppXylene lt05 45 lt05 Styrene lt05 25 lt05 a-Xylene lt05 16 lt05 Benzaldehyde lt05 16 lt05
conducted a year earlier in the fall of 1977 A much larger fire was burning north of Packwood in Washingtons Cascade Mountains on October 18 1977 This was a bright sunny day in eastern Washington with gradient winds crossing the Cascade Mountains from west to east Smoke from the Packwood burn could be seen for about 50 mi as it drifted east ward into the central part of Washington State Figure 3 shows the location of the prescribed burn and the direction of plume flow Cross-plume traverses at distances of 15 and 30 mi downwind of the burn showed a plume width of 15 and
MI Rainier A Smoke
p~ SlashG~ Burn
bull Packwood
1 1 1 0 20mi
L_-=------ Scale
1 Figure 3 Map showing the region 10lt Packwood slash burn
plume study
2 mi respcctively Vertically the plume was confined to il region uetwe(-n about 6800 and 8000 ft Figure 4 indicates maximum OJ buildup in the plume at arious points downshywind of the fire
The difference uctw(middotcn OJ concentrations in and out of the plume was aultut the ~i1me (-10 ppu) fur the Packwood emisshy~ions as that rpound(orded in the sm llc r firpound s tudied in 19-8 Ho (middoter due to the otrontu pre i ~ - b windlt (middotIlmiddotat(middotd oxishydnt Itvel5 wde rtcordd at much grt-atu di ta nn-s c owrwind
June 1981 Volume 31 No6
I -- ~-r-IPackwood - - - shyBum ~ S f-- -____ ~[
A03=55ppb shyA03 z 4Oppb A03=4Oppb
Figure 4 Schematic diagram showing ozone buildup (03) at various distances downwind of the Packwood burn
of the Packwood burn A vertical aircraft sounding 50 mi east of Packwood (downwind) showed a band of high OJ between about 7000 and 10000 ft Figure 5 shows temperature and OJ changes recorded during the vertical profile An OJ maximum of 130 ppb was observed at approximately 9000 ft While it is not possible to unambiguously ascribe the 0 3 bulge at 9000 ft to emissions from the Packwood burn it is certainly the most likely source
Discussion
Based on the data presented OJ production occurs very rapidly in slash burn plumes Often OJ has begun to accushymulate in the plume very close to the location of the burn In fact on several occasions excess OJ was observed directly above the forest burn These elevated OJ levels are the result of ample amounts of reactive hydrocarbons a favorable NOzINO ratio and sufficient sunlight to initiate and sustain photochemical reactions
Data from Figures 1 and 4 and Table II illustrated these points The HCNOx ratio in the burn plume above the fire on Octouer 251978 was 99 which is in the optimum range for photochemical oxidant formation ls Evidence for the inshyvolvement of these ozone precursor species in photochemical processes includes (I) the rapid conversion of NO to N02 as shoym in Figure 1 and (2) the preferential loss of the more photochemically reactive hydrocarbons Table 1I illustrates this latter feature by listing HC concentration changes with distance (time) The more reactive olefinic species decreased by an average factor of 56 at the point of maximum OJ buildup while the paraffins and less react ive mult iple bonded species exhibited an average concentration dlcrrase of 3t If this factor of 33 is ascribed to dilution the average olefinic change can be divided into approximntely GOr( dilution lnd 40 chemical loss
35 40 45 50 55 60 65
Temp (OF)
3L--L~__~-L__L-~__________~~
70 80 90 100 110 120130 OJ (pgtbl
FliHtt 5_ Vt--r al OlOf le --j ~j mvr a Ue ~ cf ~ C n e
OO middotn lnd oe PacJ ~ood brn
ES3
----------------------------~----------
T bJe II Hydrocarbon concentration (ppbC) changes from a References
a I In the slash burn plume directly over the burn and 35 miles pom f 0 b Iddownwind in the plume at the locatIOn 0 maximum 3 UI up 1 L Fritschen et al Slash Fire Atmospheric Pollution USDA
35 miles downwind Concentration
In plume in plume ratio over burn (03 Max) (over bum03 Max)
Ethane Ethylene Acetylene propane i-Butane
998 129
210 311
23
285 398
62 93 10
35 3_2 34 33 23
n -Butane 89 23 39 i-Pentane 56 15 37 n-Pentane 33 10 33
average 33
Propene 765 190 39 I-Butene 155 30 52 i -Butene 89 15 59 t -2-Butene 13middotButadiene
167 26 64
c-2-Butene 111 14 79 I-Pentene 45 10 45
average 56
TNMHC 642 142 45
Based on the highly reactive nature of the HC mix and the optimum HCINOz ratio it would be expected that photoshychemical oxidants would be produced rapidly and conseshyquently transport processes would involve the advection of these initially produced oxidants with little continued proshyduction as the plume drifted downwind This appears to be borne out by the ambient measurements As illustrated in Figure 4 03 levels were highest two miles downwind of the burn and then showed a dilution effect at distances further downwind
The impact of oxidants produced in slash burn plumes on downwind air quality will be highly dependent on meteorology and the elevation of the fire relative to receptor areas In both of the examples cited above plume generated oxidants reshymained aloft and therefore had a negligible effect on ground level pollutant concentrations However it is very likely that a large slash burn or uncontrolled gtildfire burning at the same elevation as a downwind receptor area could contribute sigshynificantly to surface 0 3 levels Indirect evidence for this has been reported recently in Norway where O~ levels in excess of 100 ppb were recorded during the period when a forest fire was burning 40 mi upwind of a ground level monitoring sitelI
Acknowledgment
We wish to thank the Emironmental Sciences Research Laboratory US Environm(ntal Protection Agncy for supshyporting this work
Forest and Range Experiment Station Portland OR 1970 2 D E Ward et al An Update on Particulate Emissions from
Forest Fires presented at the 69th Air Pollution Control Assoshyciation Annual Meeting Portland OR 1976
3 C Yamante Development of Emission Factors for Estimating Atmospheric Emissions from Forest Fires US Environmental Protection Agency publication EPA-4503-73-oo9 October 1973
4 C Yamante J Stockman An Inventory of Emissions for Forest Wildfires Forest Managed Burns and Agricultural Burns presented at the 68th Air Pollution Control A~sociation Meeting Boston MA 1975
5 D V Sandberg S C Pickford E F Darley Emissions from slash burning and the influence of flame retardant chemicals JAPCA 25 278 (1975)
6 E F Darley F R Burleson E H Mateer J T Middleton V P Osterli Contribution of burning of agricultural wastes to photochemical air pollution JAPCA II 685 (1966)
7 J J McElroy Agriculture and Air Pollution-Report 1959 University of California Extension Service Berkely CA 1959
8 M Feldstein S Duckworth H C Wohlers B Linsky The contribution of the open burning of land clearing debris to air pollution JAPCA 13 542 (1963)
9 L F Evans J A Weeks A_ J Eccleston D R Pockham Phoshytochemical ozone in smoke from prescribed burning of forests Environ Sci Technol II 896 (1977)
10 L F Radke J L Stith D A Hegg P V Hobbs Airborne studies of particles and gases from forest fires JAPCA 28 30 (January 1978)
11 J Schjoldager B Sivertsen J E Hanssen On occurrence of photochemical oxidants at high latitudes Atmos Environ 12 461 (1978)
12 W H Benner P Urone Photoch~mical Potential of Forest Fire Smoke pre~ented at the 70th Annual Meeting of the Air Polshylution Control Association Toronto Canada June 1977
13 Impact of Forestry Burning Upon Air Quality GEOMET Inc Report No EPA 9109-78-052 US Environmental Protection Agency 1978
14 H middotestberg K Allwine E Robinson Me3sur~ment of Light Hydrocarbons and Oxidant Transport-Houston Study 1976 Report No EPA 6003-78-062 US Environmental Protection Agency 1978
IS B Dimitriades Effects of hydrocarbons and nitro~en oxides on photochemical smog formation Environ Technol 6 253 (1972)
Dr middot(middot stherg is a faculty member in the D(partment of Chemical Engineering Air Resources S(ction at Washington State l1niversity Pullman VA 99164 Mr Sexton is in the Dlp~rtrncnt of Environmental Health Scipnces Harvard Schol of Public Health 677 Huntington Ave Roslon MA 02115 Mr Flyckt is with Dames und Moore Atmospheric S(rviccs HOllston TX 17092
J middotr31 of h c Air Pollu~ion Contr ol Association 664
o Table I Hydrocarbon concentrations (ppbC) measured during October 251978 slash burn
35 miles Upwind In plume downwind in 2 mi 15 mi 30 mi
of burn over burn burn plume
Total NMHC 135 642 142
Individual Species
Ethane 32 998 285 Ethylene 05 129 398 Acetylene lt05 210 62 Propane 14 311 93 Propene lt05 765 198 i-Butane lt05 23 10 n-Butane 19 89 23 I-Butene lt05 155 30 i-Butene lt05 89 15 13-Butadiene lt05 167 26t-2-Butene c-2-Butene lt05 111 14 imiddotPentane 05 56 15 n-Pentene lt05 33 10 I-Pentene lt05 45 10 n-Hexane lt05 21 12 Benzene lt05 638 108 n-Heptane lt05 24 lt05 Toluene lt05 245 33 Furfural lt05 129 lt05 Ethylbenzene lt05 24 lt05 m amppXylene lt05 45 lt05 Styrene lt05 25 lt05 a-Xylene lt05 16 lt05 Benzaldehyde lt05 16 lt05
conducted a year earlier in the fall of 1977 A much larger fire was burning north of Packwood in Washingtons Cascade Mountains on October 18 1977 This was a bright sunny day in eastern Washington with gradient winds crossing the Cascade Mountains from west to east Smoke from the Packwood burn could be seen for about 50 mi as it drifted east ward into the central part of Washington State Figure 3 shows the location of the prescribed burn and the direction of plume flow Cross-plume traverses at distances of 15 and 30 mi downwind of the burn showed a plume width of 15 and
MI Rainier A Smoke
p~ SlashG~ Burn
bull Packwood
1 1 1 0 20mi
L_-=------ Scale
1 Figure 3 Map showing the region 10lt Packwood slash burn
plume study
2 mi respcctively Vertically the plume was confined to il region uetwe(-n about 6800 and 8000 ft Figure 4 indicates maximum OJ buildup in the plume at arious points downshywind of the fire
The difference uctw(middotcn OJ concentrations in and out of the plume was aultut the ~i1me (-10 ppu) fur the Packwood emisshy~ions as that rpound(orded in the sm llc r firpound s tudied in 19-8 Ho (middoter due to the otrontu pre i ~ - b windlt (middotIlmiddotat(middotd oxishydnt Itvel5 wde rtcordd at much grt-atu di ta nn-s c owrwind
June 1981 Volume 31 No6
I -- ~-r-IPackwood - - - shyBum ~ S f-- -____ ~[
A03=55ppb shyA03 z 4Oppb A03=4Oppb
Figure 4 Schematic diagram showing ozone buildup (03) at various distances downwind of the Packwood burn
of the Packwood burn A vertical aircraft sounding 50 mi east of Packwood (downwind) showed a band of high OJ between about 7000 and 10000 ft Figure 5 shows temperature and OJ changes recorded during the vertical profile An OJ maximum of 130 ppb was observed at approximately 9000 ft While it is not possible to unambiguously ascribe the 0 3 bulge at 9000 ft to emissions from the Packwood burn it is certainly the most likely source
Discussion
Based on the data presented OJ production occurs very rapidly in slash burn plumes Often OJ has begun to accushymulate in the plume very close to the location of the burn In fact on several occasions excess OJ was observed directly above the forest burn These elevated OJ levels are the result of ample amounts of reactive hydrocarbons a favorable NOzINO ratio and sufficient sunlight to initiate and sustain photochemical reactions
Data from Figures 1 and 4 and Table II illustrated these points The HCNOx ratio in the burn plume above the fire on Octouer 251978 was 99 which is in the optimum range for photochemical oxidant formation ls Evidence for the inshyvolvement of these ozone precursor species in photochemical processes includes (I) the rapid conversion of NO to N02 as shoym in Figure 1 and (2) the preferential loss of the more photochemically reactive hydrocarbons Table 1I illustrates this latter feature by listing HC concentration changes with distance (time) The more reactive olefinic species decreased by an average factor of 56 at the point of maximum OJ buildup while the paraffins and less react ive mult iple bonded species exhibited an average concentration dlcrrase of 3t If this factor of 33 is ascribed to dilution the average olefinic change can be divided into approximntely GOr( dilution lnd 40 chemical loss
35 40 45 50 55 60 65
Temp (OF)
3L--L~__~-L__L-~__________~~
70 80 90 100 110 120130 OJ (pgtbl
FliHtt 5_ Vt--r al OlOf le --j ~j mvr a Ue ~ cf ~ C n e
OO middotn lnd oe PacJ ~ood brn
ES3
----------------------------~----------
T bJe II Hydrocarbon concentration (ppbC) changes from a References
a I In the slash burn plume directly over the burn and 35 miles pom f 0 b Iddownwind in the plume at the locatIOn 0 maximum 3 UI up 1 L Fritschen et al Slash Fire Atmospheric Pollution USDA
35 miles downwind Concentration
In plume in plume ratio over burn (03 Max) (over bum03 Max)
Ethane Ethylene Acetylene propane i-Butane
998 129
210 311
23
285 398
62 93 10
35 3_2 34 33 23
n -Butane 89 23 39 i-Pentane 56 15 37 n-Pentane 33 10 33
average 33
Propene 765 190 39 I-Butene 155 30 52 i -Butene 89 15 59 t -2-Butene 13middotButadiene
167 26 64
c-2-Butene 111 14 79 I-Pentene 45 10 45
average 56
TNMHC 642 142 45
Based on the highly reactive nature of the HC mix and the optimum HCINOz ratio it would be expected that photoshychemical oxidants would be produced rapidly and conseshyquently transport processes would involve the advection of these initially produced oxidants with little continued proshyduction as the plume drifted downwind This appears to be borne out by the ambient measurements As illustrated in Figure 4 03 levels were highest two miles downwind of the burn and then showed a dilution effect at distances further downwind
The impact of oxidants produced in slash burn plumes on downwind air quality will be highly dependent on meteorology and the elevation of the fire relative to receptor areas In both of the examples cited above plume generated oxidants reshymained aloft and therefore had a negligible effect on ground level pollutant concentrations However it is very likely that a large slash burn or uncontrolled gtildfire burning at the same elevation as a downwind receptor area could contribute sigshynificantly to surface 0 3 levels Indirect evidence for this has been reported recently in Norway where O~ levels in excess of 100 ppb were recorded during the period when a forest fire was burning 40 mi upwind of a ground level monitoring sitelI
Acknowledgment
We wish to thank the Emironmental Sciences Research Laboratory US Environm(ntal Protection Agncy for supshyporting this work
Forest and Range Experiment Station Portland OR 1970 2 D E Ward et al An Update on Particulate Emissions from
Forest Fires presented at the 69th Air Pollution Control Assoshyciation Annual Meeting Portland OR 1976
3 C Yamante Development of Emission Factors for Estimating Atmospheric Emissions from Forest Fires US Environmental Protection Agency publication EPA-4503-73-oo9 October 1973
4 C Yamante J Stockman An Inventory of Emissions for Forest Wildfires Forest Managed Burns and Agricultural Burns presented at the 68th Air Pollution Control A~sociation Meeting Boston MA 1975
5 D V Sandberg S C Pickford E F Darley Emissions from slash burning and the influence of flame retardant chemicals JAPCA 25 278 (1975)
6 E F Darley F R Burleson E H Mateer J T Middleton V P Osterli Contribution of burning of agricultural wastes to photochemical air pollution JAPCA II 685 (1966)
7 J J McElroy Agriculture and Air Pollution-Report 1959 University of California Extension Service Berkely CA 1959
8 M Feldstein S Duckworth H C Wohlers B Linsky The contribution of the open burning of land clearing debris to air pollution JAPCA 13 542 (1963)
9 L F Evans J A Weeks A_ J Eccleston D R Pockham Phoshytochemical ozone in smoke from prescribed burning of forests Environ Sci Technol II 896 (1977)
10 L F Radke J L Stith D A Hegg P V Hobbs Airborne studies of particles and gases from forest fires JAPCA 28 30 (January 1978)
11 J Schjoldager B Sivertsen J E Hanssen On occurrence of photochemical oxidants at high latitudes Atmos Environ 12 461 (1978)
12 W H Benner P Urone Photoch~mical Potential of Forest Fire Smoke pre~ented at the 70th Annual Meeting of the Air Polshylution Control Association Toronto Canada June 1977
13 Impact of Forestry Burning Upon Air Quality GEOMET Inc Report No EPA 9109-78-052 US Environmental Protection Agency 1978
14 H middotestberg K Allwine E Robinson Me3sur~ment of Light Hydrocarbons and Oxidant Transport-Houston Study 1976 Report No EPA 6003-78-062 US Environmental Protection Agency 1978
IS B Dimitriades Effects of hydrocarbons and nitro~en oxides on photochemical smog formation Environ Technol 6 253 (1972)
Dr middot(middot stherg is a faculty member in the D(partment of Chemical Engineering Air Resources S(ction at Washington State l1niversity Pullman VA 99164 Mr Sexton is in the Dlp~rtrncnt of Environmental Health Scipnces Harvard Schol of Public Health 677 Huntington Ave Roslon MA 02115 Mr Flyckt is with Dames und Moore Atmospheric S(rviccs HOllston TX 17092
J middotr31 of h c Air Pollu~ion Contr ol Association 664
----------------------------~----------
T bJe II Hydrocarbon concentration (ppbC) changes from a References
a I In the slash burn plume directly over the burn and 35 miles pom f 0 b Iddownwind in the plume at the locatIOn 0 maximum 3 UI up 1 L Fritschen et al Slash Fire Atmospheric Pollution USDA
35 miles downwind Concentration
In plume in plume ratio over burn (03 Max) (over bum03 Max)
Ethane Ethylene Acetylene propane i-Butane
998 129
210 311
23
285 398
62 93 10
35 3_2 34 33 23
n -Butane 89 23 39 i-Pentane 56 15 37 n-Pentane 33 10 33
average 33
Propene 765 190 39 I-Butene 155 30 52 i -Butene 89 15 59 t -2-Butene 13middotButadiene
167 26 64
c-2-Butene 111 14 79 I-Pentene 45 10 45
average 56
TNMHC 642 142 45
Based on the highly reactive nature of the HC mix and the optimum HCINOz ratio it would be expected that photoshychemical oxidants would be produced rapidly and conseshyquently transport processes would involve the advection of these initially produced oxidants with little continued proshyduction as the plume drifted downwind This appears to be borne out by the ambient measurements As illustrated in Figure 4 03 levels were highest two miles downwind of the burn and then showed a dilution effect at distances further downwind
The impact of oxidants produced in slash burn plumes on downwind air quality will be highly dependent on meteorology and the elevation of the fire relative to receptor areas In both of the examples cited above plume generated oxidants reshymained aloft and therefore had a negligible effect on ground level pollutant concentrations However it is very likely that a large slash burn or uncontrolled gtildfire burning at the same elevation as a downwind receptor area could contribute sigshynificantly to surface 0 3 levels Indirect evidence for this has been reported recently in Norway where O~ levels in excess of 100 ppb were recorded during the period when a forest fire was burning 40 mi upwind of a ground level monitoring sitelI
Acknowledgment
We wish to thank the Emironmental Sciences Research Laboratory US Environm(ntal Protection Agncy for supshyporting this work
Forest and Range Experiment Station Portland OR 1970 2 D E Ward et al An Update on Particulate Emissions from
Forest Fires presented at the 69th Air Pollution Control Assoshyciation Annual Meeting Portland OR 1976
3 C Yamante Development of Emission Factors for Estimating Atmospheric Emissions from Forest Fires US Environmental Protection Agency publication EPA-4503-73-oo9 October 1973
4 C Yamante J Stockman An Inventory of Emissions for Forest Wildfires Forest Managed Burns and Agricultural Burns presented at the 68th Air Pollution Control A~sociation Meeting Boston MA 1975
5 D V Sandberg S C Pickford E F Darley Emissions from slash burning and the influence of flame retardant chemicals JAPCA 25 278 (1975)
6 E F Darley F R Burleson E H Mateer J T Middleton V P Osterli Contribution of burning of agricultural wastes to photochemical air pollution JAPCA II 685 (1966)
7 J J McElroy Agriculture and Air Pollution-Report 1959 University of California Extension Service Berkely CA 1959
8 M Feldstein S Duckworth H C Wohlers B Linsky The contribution of the open burning of land clearing debris to air pollution JAPCA 13 542 (1963)
9 L F Evans J A Weeks A_ J Eccleston D R Pockham Phoshytochemical ozone in smoke from prescribed burning of forests Environ Sci Technol II 896 (1977)
10 L F Radke J L Stith D A Hegg P V Hobbs Airborne studies of particles and gases from forest fires JAPCA 28 30 (January 1978)
11 J Schjoldager B Sivertsen J E Hanssen On occurrence of photochemical oxidants at high latitudes Atmos Environ 12 461 (1978)
12 W H Benner P Urone Photoch~mical Potential of Forest Fire Smoke pre~ented at the 70th Annual Meeting of the Air Polshylution Control Association Toronto Canada June 1977
13 Impact of Forestry Burning Upon Air Quality GEOMET Inc Report No EPA 9109-78-052 US Environmental Protection Agency 1978
14 H middotestberg K Allwine E Robinson Me3sur~ment of Light Hydrocarbons and Oxidant Transport-Houston Study 1976 Report No EPA 6003-78-062 US Environmental Protection Agency 1978
IS B Dimitriades Effects of hydrocarbons and nitro~en oxides on photochemical smog formation Environ Technol 6 253 (1972)
Dr middot(middot stherg is a faculty member in the D(partment of Chemical Engineering Air Resources S(ction at Washington State l1niversity Pullman VA 99164 Mr Sexton is in the Dlp~rtrncnt of Environmental Health Scipnces Harvard Schol of Public Health 677 Huntington Ave Roslon MA 02115 Mr Flyckt is with Dames und Moore Atmospheric S(rviccs HOllston TX 17092
J middotr31 of h c Air Pollu~ion Contr ol Association 664