Cremlyn, R. Pesticides: Preparation and Mode of Action; John Wiley and Sons: Chichester, England, 1978; p 142. Test Methods for Evaluating Solid Waste, 3rd ed.; Office of Solid Waste and Emergency Response, U.S. Environmental Protection Agency: Washington DC, 1986; Vol. 1B. Grorud, R. B.; Forrette, J. E. J . Assoc. Anal. Chem. 1983, 66, 1220-1225. Grorud, R. B.; Forrette, J. E. J. Assoc. Anal. Chem. 1984, 67,837-840. Blakely, C. R.; Vestal, M. L. Anal. Chem. 1983,55, 750. Willoughby, R. C.; Browner, R. F. Anal. Chem. 1984,56, 2626-2631. SAS Institute Inc. S A S I S T A p M Guide for Personal Computers, Version 6 Edition; SAS Institute Inc.: Cary, NC, 1987; p 1028.
Acknowledgments We thank the individuals and laboratories who volunteered their time and efforts to this study: Dr. Robert Betham; Dr. Mark Brown, California Department of Environmental Services; ENSECO; Dr. Thomas Behymer, U S . EPA, EMSL-Cincinnati; Dr. Paul Goodley, Hewlett-Packard Corp.; Dr. Mark Roby and Chris Pace, Lockheed Engineering and Sciences Co.; and Dr. Jack Northington, West Coast Analytical Services. Registry No. 2,4-D, 94-75-7;2,4,5-T, 93-76-5;MCPA, 94-74-6; MCPP, 7085-19-0; 2,4,5-TP, 93-72-1; 2,4-DP, 94-82-6; dalapon, 75-99-0;dichloroprop, 120-36-5;2,4,5-T butoxyethanol ether ester, 2545-59-7; dinoseb, 88-85-7; dicamba, 1918-00-9.
Literature Cited Betowski, L.D.; Jones, T. L. Enuiron. Sci. Technol. 1988, 22, 1430-1434. Parker, C. E.; Haney, C. A,; Harvan, D. J.; Haw, J. R. J. Chromatogr. 1982,242, 77-96. Jones, T. L.;Betowski, L.D.; Yinon, J. In Liquid ChromatographylMass Spectrometry: Applications in Agricultural, Pharmaceutical, and Environmental Chemistry; Brown, M. A., Ed.; ACS Symposium Series 420; Americal Chemical Society: Washington DC, 1990; pp 62-74.
Received for review October 24, 1990. Revised manuscript received April 5, 1991. Accepted April 10, 1991. Notice: Although the research described in this article has been supported by the United States Environmental Protection Agency, it has not been subjected to Agency review and, therefore, does not necessarily reflect the views of the Agency, and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement nor recommendation for use.
Effect of Temperature on the Formation of Photochemical Ozone in a Propene-NO,-Air-Irradiation System Shlro Hatakeyama, Hajlme Aklmoto, and Nobuakl Washlda National Institute for Envlronmental Studles, Tsukuba, Ibaraki 305, Japan The profile of ozone formation in a propene-NO,-airirradiation system was studied at 20,30,40, and 50 "C in order to clarify the effect of temperature. The higher the temperature, the faster the formation of ozone and the longer the duration of a high concentration of ozone. The former phenomenon was due to the effect of temperature on the stability of HOON02, and the latter was due to faster decomposition of PAN at higher temperatures. Computer simulation was employed to realize the mechanism for those temperature effects. Introduction It is now well recognized that the global warming is a real threat for mankind. The rise of temperature within this century was observed to be -0.6 "C (I). Additional future warming is predicted (2-5) and its effects on global climate as well as on human life are discussed intensively (6). Among the effects of global warming, the effect on the quality of the urban atmosphere is one of the important problems. However, little information is available so far. Only one report by Carter et al. (7) was made as to experimental studies of the effect of temperature on photochemical smog formation. They observed increased rates of formation of ozone, consumption of hydrocarbons and NO,, and conversion of NO to NO2 and, also, a second maximum of ozone at a high temperature, which was ascribed to the thermal decomposition of PAN. Recently, Gery et al. (8) reported the results of modeling studies on the effect of temperature change on ozone formation. An increase of ozone due to an increase of surface temperature was simulated. However, experimental data are not yet sufficient enough to discuss the mechanism of the tem1884
Envlron. Scl. Technol., Vol.
25, No. 11, 1991
perature effect on ozone formation. In the present study we performed smog chamber experiments to investigate the dependence of ozone formation on temperature in the photochemical reactions of propene-N0,-humid air systems. Computer simulation was also done to understand the mechanism controlling the difference in the profile of ozone formation. Although the predicted change in temperature in global warming is less than a few degrees Celsius [l-5 "C by 2050 (9) is one of higher predictions], temperatures with much wider ranges were employed in the present study in order to make the results more visible. Experimental Section All the experiments were carried out in the evacuable smog chamber (6 m2),whose inner surface is coated with tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Details about this chamber were already reported (IO). The chamber wall was temperature-controlledwithin fl "C at 20, 30, 40, and 50 "C. Photoirradiation was performed by 19 Xe arc lamps (light intensity as measured by the NO2 photodissociation constant, k,,was 0.29 min-'). Experiments were performed under 1 atm of air. Propene was chosen as a model hydrocarbon in hydrocarbon-NO,-humid air-irradiation systems. Initial concentrations of reactants were [propene], = 2 ppm, [NO], = 0.26 ppm, [NO,], = 0.48 ppm, and [H2010= 5.8-6.5 Torr. Since we had already found that the formation of HONO by the heterogeneous reaction of NO2 and H20 is very important as an initial source of OH radical (11),care was taken to keep the experimental procedure nearly the same for each run. First purified dry air was passed through a humidifier and introduced into the chamber up
0013-936X/91/0925-1884$02.50/0
0 1991 American Chemical SOCletY
-1
L
'1
I
.....
I
I
...
\
. 0
I
120
.
--
.
.
-----------
_____
300
0
1
4
5
-- -
to -750 Torr. Propene, NO, and NO2were taken in a bulb of known volume one after another and introduced into the chamber in this order with a stream of pure dry nitrogen. Final total pressure within the chamber was 760 Torr. Then the dew point of the air was measured and irradiation was started 20 min after the introduction of NO2. Irradiation was continued for 6 h. For the purpose of comparison, methyl nitrite was used to realize a high initial concentration of oxidative radicals such as OH and HOz. Those radicals are produced by following reactions. CH30N0 + hv CH30 + NO (1) CH30 + O2 HCHO + H 0 2 (2) HO2 + NO OH + NO2 (3) Initial conditions were [propeneIo = 2 ppm, [CH3ONOIo = 0.25 ppm, and [NO], = 0.5 ppm at 30,40, and 50 "C. Dry buffer air was used in these experiments. Irradiation was continued for 2 h. Instruments used for the analysis of gases were LP-FTIR (Block Engineering-Jasco,FTS-496s; path length 221.5 m, number of scans 64,resolution 1cm-'), a chemiluminescent NO, analyzer (Monitor Labs., Model 8440L), and a chemiluminescent O3 analyzer (Monitor Labs., Model 8410). The absorptivities (base 10, Torr-' m-l at 30 "C) used for IR analyses were as follows: propene, 0.384 (912 cm-l); HCHO, 0.25 (2780 cm-'); CH3CH0,4.05 X (2706 cm-'); PAN, 1.83 (1160 cm-'). Propene (Takachiho, 99.5 9%) was used without further purification. NO (Matheson) was purified with several freeze-thaw cycles in a bulb containing ascarite (Arthur H. Thomas Co.) and was cooled with liquid N2. NO2 was purified by adding excess O2to convert contaminant NO to NO2 until pure white solid was observed when cooled at liquid N2temperature. Methyl nitrite was prepared by the nitrosation of methanol (12),stored at 77 K, and used after trap-to-trap distillation. Computer modeling of the photochemical reactions was performed on a HITAC M-280H computer using a new program (BOXCHEM) developed in this laboratory, which can incorporate pressure and temperature dependence of reactions in any analytical form. The subroutine employs the Gear algorithm (13) for the variable step-size integration. The detailed reaction mechanism used in this study is based on the one reported by Akimoto (14) with some modification. Temperature- and/or pressure-dependent reaction rate parameters were used. A total of
2
3
6
Time/ h
360
Figure 1. Typical time profiles of reactants and products in a propene-NO,-humId air-Irradiation system at 30 "C. Time profile of slmuiated concentration of CH , , (long broken line), ozone (solid line), NO (broken line), NOz(dotted line), and PAN (dot-ancklash line) were plotted with observed propene (open square), ozone (closed square), PAN (closed circle), and NO (cross).
+
-. -.
______________
:------.--180 240 Time/min
-
----.-.
Figure 2. Time profile of the concentration of ozone and PAN In propene-NO,-humid air-Irradiation systems at 20 (soild line), 30 (dot-anddash line), 40 (dotted line), and 50 "C (broken line). Initial conditions are [propene], = 2 ppm, [NO,], = 0.48 ppm, [NO], = 0.26 ppm, and [H,O], = 5.8-6.5 Torr.
82 chemical species and 133 equations were dealt with in the model. All the equations, functions, and parameters are listed in Table I.
Results and Discussion Figure 1 shows the observed typical time profiles of reactants and products in a propene-NO,-humid air-irradiation system at 30 "C (symbols) and the simulated profiles of reactants and products for this run (lines). Reasonable agreement between observed and calculated values can be seen. Figure 2 shows the time profile of concentrations of ozone and PAN at 20,30,40, and 50 "C. Two remarkable features were observed in this figure: (1)the higher the temperature, the faster the formation of ozone and PAN; (2) the higher the temperature, the longer the high concentration of ozone continued (the result for 50 "C showed an exceptional profile on the later stage of the reaction; the reason will be discussed later). Effect of Temperature on the Profile of Ozone Formation. The ozone formation rate depends mainly on the rate of conversion of NO to NO2, which is known to be controlled by the concentration of peroxy radicals (15). The observed temperature effect is expected to be the result of the temperature dependence of the overall reactions that accumulate peroxy radicals. Therefore it was expected that if the initial concentration of peroxy radicals was very high, the effect of temperature on the formation rate of ozone became unimportant. Figure 3 shows the formation profile of ozone in propene-CH,ONO-dry air-irradiation systems at 30,40, and 50 "C, where OH and H 0 2 are produced at a high concentration by the reactions 1-3. Results were as expected. It is clearly seen that the formation of ozone at each temperature is nearly the same, whereas the decay of ozone after its maximum was reached shows a dependence on temperature. The reactions and the species that are closely related to the formation of peroxy radicals and, thus, the formation of ozone are as follows. CH3CH=CH2 + 0, (OH, 0,) R02, H 0 2 (4) RO2, HOz + NO NO2 (5) NO2 reservoir species (PAN, HOON02, etc.) (6) NO2 + h~ NO + 0 (7) 0 + O2 + M O3+ M (8) Among these reactions, reactions 5 and 8 and the propene
-
-
-
+
Envlron. Sci. Technol., Vol. 25, No. 11, 1991 1885
Table I. Photochemical Reaction Model for the C3H6-N0,-Air Systema no.
-+ -
reaction rate constant
Photochemical Reactions NO + o ( 3 ~ ) 4.8 x 10-3 O3 + hu 0.170('D) + 0.830(3P) + O2 1.2 x 10-4 HONO hu OH + NO 7.2 x 10-4 HzO2 + h~ 20H 2.4 X lo4 NO3 + hv 0.25NO + 0.2502 + 0.76NO2 + 0.750(3P) 8.3 X HCHO + hu (+OJ 0.40H02 + 0.40HCO + 0.60H2 + 0.60CO 2.5 x 10-5 1.3 x 10-5 CH3CH0 + hv (+02) CH302+ HCO 1.3 x 10-5 C2HsCHO + hu (+Oz) C2H5O2 + HCO CH3COCHO + h , (+02) ~ CH3COO2 + HCO 7.2 x 10-4 CHZCO + hv (+(I,) 0.20CH202 + 0.80CHzOO + CO 5.9 x 10-5 CH30N0 + hu -* CH30 + NO 6.2 x 10-4 CzH50N0 + hu C2H50+ NO 6.2 x 10-4
NO^ + hu
1
2 3
- -
4
11
12
C C C C
c
.
c C C C C
-+
- --- ----
Inorganic Reactions
O(3P) + Oz + M O3 + M OPP) + NO:, NO + o2 O(3P) + NO2 + M NO3 + M O(3P) + NO + M NO2 + M O(3P) + O3 2 0 2 o ( ~ D )+ N~ o ( 3 ~+)N~ OVD) + o2 o ( 3 ~+)o2 O('D) + H 2 0 2QH O(lD) + O3 2 0 , O(lD) + O3 O2 + 20(3P) O3+ NO NO2 + O2 O3 + NO2 NO3 + O2 O3 + OH H 0 2 + O2 O3 + HO,! OH + 202 2N0 + 0 2 2N0p NO + NO3 2N02 NO + OH + M HONO + M NO + H 0 2 OH + NO2 NOp + NO3 + M -* N2O5 + M NO2 + NO3 NO + NO2 + 02 NO2 + OH + M HNO3 + M NO2 + HO2 + M HO2N02 + M H 0 2 N 0 2 H 0 2 + NOp
--
-- + - + + - + - +
36 HOzN02 OH HpO + NO2 + 0 2 37 HONO + OH H2O NO2 38 HN03 OH H 2 0 NO3 39
N2O5
40 41 42 43 44
HOz + HO2 -+ H2Oz + 0 2 HO2 + HO2 + M H202 + 02 Hop + H02 + H2O -+ H202 + 02 + H2O H202 + OH HO2 + HzO CO + OH (+02) HOp + COP
NO2
NO3
--
45 O3 46 47 48 49 50
b
-+
--
-+ + -
dep HONO H 2 0 HONO H 2 0 2HN03 dep
-+
.
C3H6+ O(3P) Reactions 51 C3H6 + O(3P) (+02) 0.3CH3CHCH20 + 0.3C2H5CH0+ 0.2CH2C0 + 0.2HO2 + 0.2CH302 + 0.2C2H502+ 0.2HCO 52 CH302+ NO CH30 + NO2 53 C2H5O2+ NO-C2H50 + NO2 54 CH30z + NO2 + M CH302N02+ M 55 CH302N02 CHSO2 + NO2
-
-
- -
56 CzHb02 + NO2 + M -* C2H502N02 + M 57 C2H502NOZ- C2H5O2 + NO2
-
58 CH30z + H 0 2 CH300H + O2 59 CzH502 + H02- CzH500H + 02 60 CH3O2 + CH30p 0.7CH30 + 0.57HCHO 0.08CH3COOH + 02 61 C2H5O2 + C2H5Op 2C2H50 + O2 1888
FNC3(6.0 X 2.3, 0.0, 0.0, CM, T) FNCl(6.5 X 10-l2, -120, T) FNC3(9.0 X 2.0, 2.2 X lo-", 0.0, CM, T) FNC3(9.0 X 1.5, 3.0 X lo-", 0.0, CM, T) FNCl(8.0 x 10-l2, 2060, T) FNCl(1.8 X lo-", -110, T) FNCl(3.2 X lo-", -70, T) 2.2 x 10-10 1.2 x lo"@ 1.2 x 10-10 1400, T) FNCl(2.O X FNCl(1.4 X 2500, T) FNCl(1.6 x 10-l2, 940, T) FNCl(1.1 X 500, T) FNCl(3.3 X 530, T) FNCl(l.7 X lo-", -150, T) FNC3 (7.0 X 2.6, 1.5 X lo-", 0.5, CM, T) FNCl(3.7 X lo-'', -240, T) 4.3, 1.5 X 0.5, CM, T) FNC3(2.2 X 1230, T) FNCl(2.5 X FNC3(2.6 X 3.2, 2.4 X lo-", 1.3, CM, T) FNC3(1.8 X 3.2, 4.7 X 10'l2, 1.4, CM, T) 3.2, 4.7 x 1.4, 2.1 x FNC4U.8 x 10900, CM, T) FNCl(1.3 X 10-l2, -380, T) FNCl(1.8 x lo-", 390, T) FNC5(7.2 X 10-15, 4.1 X 10-l6, 1.9 X 785, 1440, 725, CM, T) FNC4(2.2 X 4.3, 1.5 X 0.5, 1.1 X 11200, CM, T) FNCl(2.3 X -600, T) FNC6(1.7 X -1000, CM, T) 3.5 x 10-30 FNCl(3.3 x 10-l2, 200, T) 2.4 x 10-13
17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 22 17 17 17
dry (8.3 X 10-s)*T-1.6 X (1.7 X 10-7)*T-3.2 X dry 7.2 X lo*; humid 1.1 X 6.5 x 10-7 2.1 x 10-23 4.5 x 10-21 8.0 x 10-5
b
17 25 17 17 17 17 17 17
Wall Reactions
dec
NO2 NO2 NOz Nz05 HN03
ref
C
-+
5 6 7 8 9 10
13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
reaction
+ 0.57CH30H +
Envlron. Scl. Technol., Vol. 25, No. 11, 1991
FNCl(1.2
X
humid
lo-", 324, T)
b 11
20 14 14 19
FNCl(4.2 X -180, T) FNCl(4.2 X 10-l2, -180, T) FNC3(1.5 X 4.0, 6.5 X 2.0, CM, T) FNC4(1.5 X 4.0, 6.5 X 10-l2, 2.0, 1.3 X 11200, CM, T) 4.0, 6.5 X 2.0, CM, T) FNC3(1.5 X 4.0, 6.5 X 2.0, 1.3 X FNC4(1.5 X 11200, CM, T) FNCl(7.7 X -1300, T) FNCl(6.5 X -650, T) FNCl(1.9 X 10-13, -220, T)
17 (52)' 17 17
FNCl(3.2
19
X
683, T)
(54)' (55)' 17 25 17
Table I (Continued) reaction
no.
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
- --
c2&) + NO 0.93C2H50N0+ 0.07CH3CH0 + 0.07HNO CH30 + NOz + M CH30NOZ+ M CH30 + NOz HCHO + HONO CzH50 + NO2 + M -* CZH5ON02 + M C2H50+ NOz CH3CHO + HONO CH,O + O2 HCHO + HOz C2H58 + 02 CH3CHO + HOZ HCO + 0 2 HO2 + CO CH3C002 9 NO (+OJ CH302 + Cop + NO2 CHqC00, + NO, + M --c PAN + M PAN cH3C062 + NO2 CH3COO2 + HOp CH3COOzH + 0 2 C2H5C002 + NO (+02) C2H5O2 + COP NO2 C2H5COOz + NO2 + M --c CZHSC002N02 M CzH,COOZNO2 CzH5C002 + NO2 C2H5C002 HOz CZHSC002H + 02
-
4
-
-
+
+ +
4
-+
.
C3Hs + o3Reactions 81 CsHn + 0 8 4 0.5CHsCHO + 0.19CH202 + 0.31CHzOO + 0.5HCHO + 0.09CH3CH02 + 0.41CH3(:H00 82 CHQOo+ NO HCHO + NO, 83 CHjCHO, + NO CH3CH0 ? NO2 84 CHzOz + NO2 HCHO + NO3 85 CH,CHOO + NO2 -. CH3CH0 + NO3 HCOOCHZOH + M 86 CHzOz + HCHO + M 87 CH202+ CH3CH0 + M propene ozonide + M 88 CH3CHOz .f HCHO + M propene ozonide + M 89 CH3CHOZ+ CH3CH0 + M butene ozonide + M 90 CH202 + H20 HCOOH + HZO 91 CH3CH02+ H2D -.CH3COOH + H 2 0 92 CH202 CHZOO ._ 93 CH3CH02 CH3CHOO 94 CHzOO (+O,) 0.18H2 + O.27CO2 + 0.67CO + 0.671 0 + 0.18H02 + 0.06HCOOH 95 CH3CHOO ( + 0 2 ) O.39CH4 + 0.13CHzCO + 0.13HzO + O.44CH3Oo + 0.29HOz + 0.190H + 0.23CO + 0.04CH30 + 0.64c02
--
+
--
+
-
. . +
reaction rate constant
ref
316, T)
19 19 19 19 24 24 (661,
FNCl(5.8 X 4.6 x 10-15 1.8 X lo-" 1.3 X lo-" 1.2 x 10-11 1.2 x 10-12 1.2 x 10-11 1.2 x 10-12 FNCl(3.9 X FNCl(7.0 X FNCl(3.5 X FNCl(4.2 X 5.4 x 10-12 FNCl(1.1 X FNCl(7.7 X FNCl(4.2 X 5.4 x 10-12 FNCl(1.1 X FNCl(7.7 X
+
-
-
FNCl(1.3
X
lo-", 900, T) 690, T) lo-'', -140, T) lo-", -180, T)
13330, T) -1300, T) lo-", -180, T) 10l6, 13330, T) -1300, T) 2104, T)
C3H6 + NOs Reactions C3H6 + NO3 (+O2) 0.65CH3CH(Oz)CHzON02 + 0.35CH3CH(ONOz)CHz02 CH&H(O)CH20N02 + NO2 CF&CH(02)CH20N02 + NO CH3CH(ON02)CH20N02 M CH3CH(02)CH20N02 + NO + M CH3CH(ON02)CH202 + NO CH3CH(ON02)CH20 + NO2 CH&H(ON02)CH20NO2 CH3CH(ONOJCH202 + NO + M CH3CH(Oz)CH2ON02 + HOz CH3CH(OOH)CH,ONO2 + 02 CH3CH(ON02)CH202 + HO2 CH3CH(ON02)CH200H + 0 2 CH&H(O)CH20N02 + NO2 + M CH3CH(ON02)CH20N02 M CH&H(ON02)CH20 + NO2 + M CH&H(ON02)CH20N02 + M CH3CH(O)CH@N02 + 02 CH3COCH20N02 + HOZ CH3CH(ON02)CH,O + 0 2 CH&H(ON02)CHO + HOZ CPJCH(O)CH~ONO~ CHSCHO + HCHO + NO2 CHBCH(ON02)CHzO CH3CHO + HCHO + NO2
9.4 x 10-15 FNCl(4.2 X FNC7(4.2 X FNCl(4.2 X FNC7(4.2 X FNCl(7.0 X FNCl(7.0 X 1.2 x 10-11 1.2 x 10-11 3.0 x 10-14 FNCl(7.0 X 3.0 x 105 3.0 x 104
+
-
-
-
+
+
-
+
-
-C
-C
+ +
19
18 (52)f 25 ' (52)f 25
115 116 117 118 119 120 121 122 123 124 125 126 127
+
+
(Wf
14 14 14
FNCl(4.9 X lo-", -504, T) FNCl(4.2 X lo-''. -180. TI 0.04~Nci(4.2x io-12, -180, T) FNCl(4.2 X lo-", -180, T) 0.04FNC1(4.2 X 10-l'. -180. T) 6.0 X lo6 6.0 X lo6 3.0 x 10-14 FNCl(7 X 690, T) FNCl(7.7 X lo-", -1300, T) FNCl(7.7 X -1300, T) 5.0 X 7.0 X FNCl(6.0 X lo-", -250, T) FNCl(4.2 X lo-", -180, T) 5.4 x 10-12 FNCl(1.1 X 10l6, 13330, T) FNCl(7.7 X lo-", -1300, T) FNCl(6.0 X lo-", -250, T)
+
(Wf
23 23 (581, (73)f (74)f (75)f
19 19 21 21 21 21 21 21 19 19
C3H6+ OH Reactions C3H6 + OH (+02) 0.65CH3CH(Oz)CHzOH + 0.35CH&H(OH)CH202 CH&H(O,)CH,OH + NO --c CHXH(O)CH,OH + NO, CH;CH(O,)CH,OH + NO + M CH3CH(6NO2)CHzOH+ M CH3CH(OH)CH202 + NO2 CH&H(OH)CHzO + NO2 CH3CH(OH)CH20N02 + M CH3CH(OH)CH20H + NO + M CH3CH(O)CH20H ( + 0 2 ) CHBCHO + HCHO + H02 CH&H(OH)CH20 ( + 0 2 ) CHSCHO + HCHO + HO2 CH&H(O)CH,OH + 02 CH3COCH2OH + HOz CH3CH(OH)CH20 + 02 CH&H(OH)CHO + HOz CH&H(OZ)CH20H + HOZ CH&H(OOH)CH,OH + 02 CH3CH(OH)CH202 + HOz CH3CH(OH)CHZOOH + 02 CH3COCHzOH + OH (+02) CH3COCHO + HOZ + H2O CH3COCHO + HOz + HZO CH,CH(OH)CHO + OH (+OJ CH,CH(OH)CHO + OH (+02) CH3CH(OH)C002 + HZO CH,CH(OH)COOz + NO (+02) CH3CHO + HO2 + COZ + NO2 CH3CH(OH)C002N02 + M CH,CH(OH)COOZ + NO2 + M CH&H(OH)C002N02 CH,CH(OH)C002 + NO2 CH3CH(OH)C002 + HO2 CH3CH(OH)C002H + 0 2 CH3COCHO + OH ( + 0 2 ) CH3C002 + CO + HZO +
17 19 17
7.0 X 7.0 X 7.0 X 7.0 X 1.8 x 10-14 1.8 x 1 0 4 4 1.8 x 1 0 4 4 1.8 x 10-14 4.0 X 4.0 X 3.6 X 3.6 X 1.0x 105 1.0x 105
96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114
----
(Wf
lo-", -180, T) lo-", -180, T)
lo-", -180, T) lo-", -180, T) lo-", 690, T) 690, T)
690, T)
Environ. Sci. Technol., Vol. 25, No. 11, 1991
1887
Table I (Continued) no.
reaction
- -
Aldehyde Reactions HCHO + OH HCO t HzO CH3CHO + OH (to,) CHSCOOZ + HzO CzH&HO + OH (to,) CzHbCOOz t HzO HCHO + NO3 H N 0 3 + HCO CHBCHOt NO3 (+Oz) HN03 + CH3COOz H N 0 3 + CzH&0O2 CzH6CH0 + NO3 (+OJ
128 129 130 131 132 133
- -+
reaction rate constant
ref
1.0 x 10-11 FNCl(6.0 X lo-", -250, T) FNCl(6.O X lo-", -250, T) 6.0 X FNCl(1.4 X 1860, T) FNCl(1.4 X 1860, T)
17 17 (129)f 17 17 (132)f
OFunctions used in this model are defined as follows. Here X**Y means the Yth power of X and ALOGlO means logarithm of base 10. (1) FNCl(Cl,CZ,T)=Cl * EXP(-CB/T). (2) FNCZ(Cl,CZ,T)=Cl * (T/300.0)**C2. (3) FNC3(Cll,C12,C21,C22,CM,T)= CM * (Cl/(l.O + ClCMC2)) * 0.6**(1.0/(1.0 + ALOGlO(ClCMC2)**2)). FNC32(Cll,C12,T)=Cll * (300.O/T)**C12. Cl=FNC32(Cll,Cl2,T). C2=FNC32(C21,C22,T). ClCMCZ= Cl*CM/C2. (4) FNC4(Cll,C12,C21,C22,C31,C32,CM,T)= FNC3(Cll,Cl2,C21,C22,CM,T)/EQCNT EQCNT=C31 * EXP(C32/T). ( 5 ) FNC5(Cl,C2,C3,C4,C5,CG,CM,T)=ClEXC4 + C3EXC6/(1.0 t C3EXC6/C2EXC5). ClEXC4=Cl * EXP(CI/T). C3EXC6=C3 * EXP(C6/T) * CM. C2EXC5=C2 * EXP(C5/T). (6) FNCG(Cl,CZ,CM,T)=Cl * EXP(-CZ/T) * CM. (7) FNC7(C1,C2,T)=Oa04* C1 * EXP(-CZ/T). *This work. CEstimatedfrom the ratios listed in ref 14. dThe rate constant was adapted from the value for 1-propanol. 'The rate constant was adapted from the value for 2-propanol. fThe rate constant was adapted from the value for the reaction indicated in Darentheses.
0
10
20
30
40
50
40
50
bU
Time/min
0
2
1
Time/h
Flgure 3. Time profile of the concentration of ozone in propeneCH,ONO-dry air-irradiation systems at 30 (dot-anddash line), 40 (dotted line), and 50 OC (broken line). Initial conditions are [propene], = 2 ppm, [CH,ONO], = 0.25 ppm, and [NO], = 0.5 ppm.
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+ OH reaction have negative activation energies (16-18), and thus, their temperature effect should be opposite to the tendency observed in the present study. Therefore, the effects of temperature on (A) propene + ozone, (B) PAN decomposition, and (C) HOON02 formation and decomposition were examined quantitatively by simulation. Results were shown in Figure 4. In parts A and B of Figure 4, only the rate constant for reaction A or B, respectively, was set to be temperature dependent and other rate constants were fixed at the value at 30 OC. The difference in the rate of initial ozone formation is not obvious. On the other hand, as is clearly seen in Figure 4C, the profile of ozone formation at 20,30,40, and 50 "C showed a large variation when the rate constants for formation and decomposition of HOONOz were made dependent on temperature. Other reactions seem to have less effect on the formation profile of ozone than on HOONOz formation and decomposition. Calculated concentrations of HOON02 and H 0 2 are depicted in Figures 5 and 6. The concentration of HOONO2 shows a remarkable dependence on temperature. Indeed, the lifetimes of HOON02 at 20,30,40, and 50 OC were calculated to be 20.7, 6.6, 2.3, and 0.8 s, respectively. Therefore, it can be concluded that at a low temperature H 0 2 and NO2 are trapped in a reservoir as HOON02. Figure 6 supports this contention. The concentration of H 0 2 also showed a significant dependence on the tem1888
Environ. Sci. Technol., Vol. 25, No. 11, 1991
30
..
I ( .
Time/min
1:
111
zr
30 ?ime/min
4
Cll
-11
Flgure 4. Simulated profiles of ozone formation with (A) temperature-dependent propene ozone rate constant, (B) temperaturedependent PAN decay rate, and (C) temperature-dependent HOONO, formation and decay rate. Other rate constants are fixed at the values of 30 OC. Temperatures are shown as 20 (solM line), 30 (dot-anddash line), 40 (dotted line), and 50 OC (broken line).
+
perature. Thus conversion of NO to NO2 is slowed down and the concentration of NO2 cannot go up rapidly. As a result, ozone formation is retarded. Observed results shown in Figure 7 support this argument. In this figure, the concentrations of NO and NOx-NO-PAN (mainly consisting of NOz in the early stages) were plotted against the reaction time. The decay of NO and buildup of NOx-NO-PAN were delayed at low temperatures. Thus,
0.8
I
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0Ell
I
/
,
w
0
10
20
30
40
50
.....
_____~
0
60
,
60
120
TFme/min
Flgure 5. Slmulated profiles of HOONOp at 20, 30, 40, and 50 "C. Temperatures are shown as 20 (soiM line), 30 (dot-anddash line), 40 (dotted line), and 50 "C (broken line).
180 Time/&
240
300
360
Flgure 8. Simulated profile of O3with the decay rate of PAN fixed at the value of 30 "C. Temperatures are shown as 20 (solid llne), 30 (dot-and-dash line), 40 (dotted line), and 50 "C (broken line).
__--
14E9 r
Y
-
0.21 0
10
20
30
40
50
60
Time/&
Figure 8. Simulated profiles of HO, at 20, 30, 40, and 50 "C. Temperatures are shown as 20 (solkl line), 30 (dot-and-dash line), 40 (dotted line), and 50 "C (broken line). 1.0
I
I-\;
I
I
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__ -
~
-
~
~
I
- -........................................................ - --- -.- -- --- ---_- _____ __ __ ____. .----_~
~
.
S'.,
0
1
2
3
4
5
6
Time/h
Flgure 7. Time profile of the concentration of NO and NO,-NO-PAN In propene-NO,-humid air-lrradlatlon systems at 20, 30, 40 and 50 OC. Initial conditions are (propene], = 2 ppm, [NOp], = 0.48 ppm, [NO],, = 0.26 ppm, and [H,O], = 5.8-0.5 Torr. Temperatures are shown as 20 (solid line), 30 (dot-anddash line), 40 (dotted line), and 50 "C (broken line).
the formation of ozone is slower at lower temperature. HOON02 showed the effect only in the early stage of the reaction where the concentration of NO2 was high. As shown in Figure 2, the decay of ozone after its maximum was reached is faster at lower temperature. As reported by Carter et al. (7), it clearly correlated with the decay of PAN. The time profile of PAN is also depicted in Figure 2. At higher temperature PAN decomposes to give NO2 according to CH&(=O)OON02 CH,C(=O)OO + NO2 (9) PAN Reproduced NO2 can serve as a source of ozone. Calculated lifetimes of PAN at 20, 30,40, and 50 "C are 5200, 1160, 285, and 75 s, respectively. The lifetime at 20 "C is 76 times as long as that at 50 "C. The simulated profile of ozone as depicted in Figure 8 also supports this contention. In this simulation the decay rate constant of PAN -+
0
0.5
1
2 2.5 [C3H6]0/ppm
1.5
3
3.5
4
Flgure 9. Dependence of maximum ozone concentration on lnltlal concentratlon of C3H, at 20, 30, 40, and 50 "C. Temperatures are shown as 20 (solid line), 30 (dot-anddash line), 40 (dotted line), and 50 "C (broken line).
I
'.'"
" . " '
0
was fixed at the value of 30 "C. The decay of ozone after its malximum is faster at higher temperatures. This tendency is opposite to that observed. In Figure 2, decay of ozone at 50 "C became rapid after 3 h. It must be due to the very rapid decomposition of PAN. The concentration of PAN became too low to maintain a high concentration of ozone after 3 h. Before 3 h the decay of ozone at 50 "C is clearly slower than that at 40 "C. Since the concentrations of propene and NO, in this study are much higher than those observed in ambient atmosphere, the applicability of the present results to the real atmosphere is not straightforward. However, the model could reproduce the experimental results well. Therefore, it may be necessary to add experiments employing low concentrations of reactants to predict the effect of temperature in the real atmosphere. Dependence of Maximum Ozone Concentration on Temperature. No clear dependence of maximum ozone concentration on temperature was observed in our experiments. Gery et al. (8) estimated an average increase of ozone of 1.6% K-' from the base case ozone of 0.12 ppm on the basis of the OZIPM-3 trajectory model. On the other hand, no clear dependence was reported in the work of Carter et al. (7). However, clear dependence of the maximum ozone concentration on temperature was observed when a lower concentration of propene was incorporated for simulation. Figure 9 shows the dependence of the calculated maximum ozone concentration on the initial concentration of propene at various temperature. Initial concentrations of NO and NO2 were 0.3 and 0.2 ppm, respectively. Around 2 ppm propene concentration no clear dependence of maximum ozone concentration on temperature was visible. This is consistent with the present experimental results. I t should be due to the destruction of ozone by the reaction with propene. HowEnviron. Sci. Technol., Vol. 25, No. 11, 1991 1889
ever, in the presence of lower concentration of propene, the maximum ozone concentration is clearly temperature dependent. In the real troposphere, where the concentration of such highly reactive hydrocarbons is low, we can assume that the daily maximum concentration of ozone is higher when the temperature is high. This is still a very qualitative argument, and clearly more detailed experimental studies with lower concentrations of hydrocarbons are needed. Conclusions The higher the temperature, the faster the formation of ozone and the longer the duration of a high concentration of ozone after its maximum was reached. Both observations can be explained in terms of the stability of reservoir species of NO2. The former result was due to the stability of HOON02. At lower temperature, NOz and HOz are trapped in a reservoir as HOON02,and the formation of NOz is delayed. HOONOzshowed the effect only in the early stage of the reaction where the concentration of NO2 was high. At the later stage, PAN plays a major role in forming ozone. At high temperature PAN decomposes to produce NO2 and peroxy radicals, which bring about enhancement of ozone formation. When the concentration of hydrocarbons is low, the maximum concentration of ozone is temperature dependent. At higher temperatures ozone reaches higher levels than at lower temperatures. In the real atmosphere, other conditions such as weather, transport, etc. may affect the ozone concentration. On the basis of the present results it can be said that the maximum concentration of ozone is higher and a high concentration of ozone continues longer at higher temperature. Thus, the exposure time of men, other animals, and plants to high concentration of ozone becomes longer if the temperature rises with global warming. Acknowledgments We are grateful to M. Watanabe of Environmental Pollution Control Center, Co. for his help in operating the chamber experiments. Registry No. PAN, 2278-22-0; 03,10028-15-6;H2C=CHCH3, 115-07-1; NO,, 11104-93-1; HOONOZ, 26404-66-0.
Literature Cited (1) Hansen, J.; Lebedeff, S. Geophys. Res. Lett. 1988,15, 323. (2) Manabe, S.; Wetherald, R. T. J . Atmos. Sci. 1975, 32, 3. (3) Manabe, S.; Bryan, K. J . Geophys. Res. 1985, 90, 11689.
1890 Envlron. Sci. Technol., Vol. 25, No. 11, 1991
(4) Hansen, J.; Johnson, E.; Lacis, A.; Lebedeff, S.; Lee, P.; Rind, D.; Russel, G. Science 1981, 213, 957. (5) Hansen, J.; Fung, I.; Lacis, A.; Rind, D.; Lebedeff, S.; Ruedy, R.; Russel, G. J . Geophys. Res. 1988, 93, 9341. (6) Bolin, B., Doos, B. R., Jager, J., Warrik, R. A., Eds. The
Green House Effect,Climatic Change, and Ecosystems; SCOPE 29; John Wiley: Chichester, England, 1986. (7) Carter, W. P. L.; Winer, A. M.; Darnall, K. R.; Pitts, J. N., Jr. Environ. Sci. Technol. 1979, 13, 1094. (8) Gery, M. W.; Edmond, R. D.; Whitten, G. Z. Tropospheric
Ultraviolet Radiation Assessment of Existing Data and Effect on Ozone Formation; EPA/600/3-87/047; 1987. (9) Dickinson, R. E.; Cicerone, R. J. Nature 1986, 319, 109. (10) Akimoto, H.; Hoshino, M.; Inoue, G.; Sakamaki, F.; Washida, N.; Okuda, M. Environ. Sci. Technol. 1979,13,471. (11) Sakamaki, F.; Hatakeyama, S.; Akimoto, H. Znt. J. Chem. Kinet. 1983, 15, 1013. (12) Hartung, W. H.; Crossley, F. Organic Syntheses; Wiley: New York, 1943; Collect. Vol. 11, p 363. (13) Gear, C. W. Numerical Initial Value Problems in Ordinary Differential Equations; Prentice-Hall: Engelwood Cliffs, NJ, 1971. (14) Akimoto, H. Res. Rep. Natl. Znst. Environ. Stud. (Jpn.) 1984, No. 59, 111 (in Japanese). (15) Seinfeld, S. H. Atmospheric Chemistry and Physics of Air Pollution; Wiley: New York, 1986. (16) Atkinson, R.; Carter, W. P. L. Chem. Rev. 1984, 84, 437. (17) DeMore, W. B.; Molina, M. J.; Sander, S. P.; Golden, D. M.; Hampson, R. F.; Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R. Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling; Evaluation Number 8, J P L Publication 87-41, J e t Propulsion Laboratory, Pasadena, CA, 1987. (18) Atkinson, R. Chem. Rev. 1986, 86, 69. (19) Atkinson, R.; Lloyd, A. C. J. Phys. Chem. Ref. Data 1984, 13, 315. (20) Akimoto, H.; Takagi, H.; Sakamaki, F. Znt. J. Chem. Kinet. 1987, 19, 539. (21) Finlayson-Pitts, B.; Pitts, J. N., Jr. Atmospheric Chemistry; Wiley: New York, 1986; p 456. (22) Graham, R. A.; Jonston, H. S. J. Phys. Chem. 1978,82,254. (23) Baulch, D. L.; Cox, R. A.; Crutzen, P. J.; Hampson, R. F., Jr.; Kerr, J. A,; Troe, J.; Watson, R. T. J . Phys. Chem. Ref. Data 1982, 11, 327. (24) Baulch, D. L.; Cox, R. A.; Crutzen, P. J.; Hampson, R. F., Jr.; Kerr, J. A.; Troe, J.; Watson, R. T. J. Phys. Chem. Ref. Data 1984, 13, 1259. (25) Atkinson, R.; Baulch, D. L.; Cox, R. A.; Crutzen, P. J.; Hampson, R. F., Jr.; Kerr, J. A.; Troe, J. J . Phys. Chem. Ref. Data 1989, 18, 881.
Received for review January 23, 1991. Revised manuscript received June 21, 1991. Accepted June 27, 1991.
