Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Chemistry and Physics Discussions Atmospheric ratios of ca. 0.1, the 2 C, it depletes exhaustively in ◦ ects their lifetimes remarkably. For ff ) play an important role in tropospheric chem- 8174 8173 2 C (the average temperature at 6 km) and NO to NO ◦ 26 − and Physics (ACP). Please refer to the corresponding final paper in ACP if available. This discussion paper is/has been under review for the journal Atmospheric Chemistry lifetime of PAN is 5.36 yrsonly 30 (Kleindienst, min 1994), (Bridier and et at al., 1991). 25 Their stable properties under low temperatures mean Peroxyacyl nitrates (PANs, RC(O)OONO istry and are better indicatorsal., of 1995) photochemical than smog ozone (Carter (Rappengluckment et et and can al., al., damage 1981; 1993, plants Schrimpf 2003). (DuggerTemple and et and They Taylor, 1983), Ting, are irritate 1968; toxic human Teklemariam eyes and tomutation (Dugger Sparks, the et (Kleindienst 2004; environ- al., et 1963), al., and lead 1990).and to ubiquitous genetic These in compounds, the especially atmosphere.PAN, PAN, at are Temperature prominent a significantly. The percentages of PANPPN loss urban at loss the was two higher sites than were that very in similar; suburban. however, 1 Introduction PAN were 11.22 ppbv and 1.95 ppbvaverage at values PKU of during 15 PPN to wereber. 27 2.51 August, Average ppbv and mixing maximum and ratios and (PAN/PPN) 0.41much were ppbv lower 5.60 at than (at Yufa those during PKU) in 2 andPPN other to 5.83 reflects metropolitan 12 (at similar areas. Yufa), Septem- volatile which High organic is correlationwas compound remarkable between origins. when PAN and compared Thermal with lossozone their of ambient have PAN concentrations. similar and PAN trend PPN and by PPNculated, with day. and Thermal results decompositions indicated of that PAN thermal and PPN losses were influence cal- their atmospheric lifetime Peroxyacetyl nitrate (PAN) and peroxypropionyl nitratetially (PPN) in were situ measured sequen- byurban an (Peking University, PKU) online and gas-phase suburban (Yufa,in chromatograph A town Beijing with in during the electron south the capture of photochemical Beijing) detector season sites at in 2006. Maximum and average values of Abstract Peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) in urban and suburban atmospheres of Beijing, China J. B. Zhang, Z. Xu, G. Yang, andDepartment B. of Wang Environmental Sciences, CollegeState of Joint Environmental Laboratory Sciences of and Environmental100871, Engineering, Simulation China and Control, Peking University, Beijing Received: 15 February 2011 – Accepted:Correspondence 22 to: February 2011 J. B. – Zhang Published: ([email protected]) 10 MarchPublished by 2011 Copernicus Publications on behalf of the European Geosciences Union. Atmos. Chem. Phys. Discuss., 11,www.atmos-chem-phys-discuss.net/11/8173/2011/ 8173–8206, 2011 doi:10.5194/acpd-11-8173-2011 © Author(s) 2011. CC Attribution 3.0 License. 5 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | c. ffi er air ff episodes have been studied comprehen- E). This is the higher than the surrounding 3 00 8176 8175 30.49 0 18 ◦ E). Zhongguancun Street is on the east side of the 00 N, 116 25.91 0 00 18 ◦ 52.63 0 30 ◦ N, 116 00 ney et al. (1999) indicated that PAN and PPN produced in megacities are likely 20.92 0 ff 59 ◦ Measurements of PAN and PPN were taken sequentially from the campus of Peking To illustrate the status of PAN and PPN pollution in urban and suburban areas and Ga site was characterized by highpollutant levels of emissions natural compared vegetation to and PKU. low local anthropogenic building. To the northbuildings, and and to west the of southarea, the is which building Fourth is are Ring densely Road. someThis populated, relatively PKU sampling with low-floor is site high located teaching should levels insampling of reflect the location human the Zhongguancun was activity air on and the pollution(15 roof heavy in m of tra a high, the typical Main 39 Teaching urban Buildingbuildings of area. and Huangpu is At University Yufa, ca. the ing 60 km district, neighboring south the of Yongding PKU. River Yufa and is on in the the border southern of Hebei suburbs Province. of The the Dax- of motor vehicles exceededincrease in 3 motorized million. transport have been In generally recent higher than years, 10%. University the (PKU; average urban) annualAt and rates PKU, Yufa of (suburban). the sampling39 Sampling location sites was are on shown the in roof Fig. of 1. the Science Building (25 m high, its southeast is a gently slopingpopulation plain in to Beijing the was Bohai 16.95 Sea.the million, At end which the of represented end a 2007. of 0.62had 2008, Beijing million the increased had increase resident to over only 26 2300under 000 motor and policies vehicles by in of 1978, 1949; reformmillion by it in and 1966, February was outreach, this 1997, 77 000. number and thethen. Beijing number has With Vehicle of entered 10 exhaust a motor2006, years pollution period the vehicles of of total plays number rapid development approached pretty of development motor 1 important since vehicles was role 2.45 million. in On Beijing’s 26 May air 2007, the quality. number In 2.1 Sampling Beijing locates in theand northwest low of in the the North southeast. China Its west, Plain north, and and is northeast high are in surrounded the by northwest mountains; 2 Methods From its highest level ofand 58 ppbv, the PAN levels average have generally concentrationpollution dropped is severely to due much below to lower. 10 photochemical ppbv, smoget Beijing (reported al., and high 2008; ozone) its Guttikunda and et surroundingssively aerosol al., (Ding there su 2005) (An et and al., O have 2007; been Duan done et apart al., fromwere 2008; those conducted Xu on et ozone. both al., Therefore,2006. in 2008). PAN The and urban However, results PPN few and were studies measurements provided suburban in the sites following of sections. Beijing during the summer of to make comprehensive comparisonsis with results provided from in other Table 1.California, sites, a during Since global the the summary last occurrenceimplemented. century, of PAN substantial and photochemical PPN smog improvements pollution in in have Los air declined Angeles, quality significantly in have the been United States. for PAN. Only a few studies haveet reported al., PAN 2008; and Sun PPN in andstudies East Huang, on Asia 1995; mainland concurrently Zhang China (Lee except and Zhang Tang,ago. 1994; and Tang Zhang (1994) More et done comprehensive by al., studies more 2009)et than have and al., a no been decade 1992; carried Singh outand and in Salas, PPN North 1989; have America Williams beenprevious and (Shepson studied Grosjean, in in 1991), situ southern and simultaneous Californiabefore. ambient study since PAN of 1960 PAN (Grosjean, and 2003). PPN in No Asia has been reported ever trogen compounds, becoming involvedquality in (Singh atmospheric et circulation, al., 1992a, and b) influencing on air local, regional,to and contribute global-scales. strongly to regional scaletransport. ozone To and date, aerosol PPN production (Grosjean, during 2003) long has range been reported in fewer studies than that that PAN and PPN can be transported long distances, acting as reservoirs for odd ni- 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). σ ana- x with NO under 3 level (Carter et al., x COCH 3 C to minimize the thermal ◦ , NO, PAN, PPN, etc. (Stein- 2 mixing ratio was estimated by sub- 2 C. The detection limits for PAN and PPN ◦ 8178 8177 were measured using a high-sensitivity NO x analyzer, ECOTECH) with a detection limit of 0.4 ppbv. x /NO analyzer measures the sum of NO 2 x Ni model maintained at 40 63 C. The volumes of helium (carrier gas) and nitrogen (make-up gas) were at ◦ After cleaning, the canisters were analyzed for the presence of VOCs to verify that All examined pollutants and corresponding meteorological parameters (including While PAN and PPN measurements were being taken, ozone (It was calibrated by All inlets (less than half a meter long with the diameter of 6 mm) were made of they were clean beforeAmbient final air evacuation samples and were theanalyzed pre-concentrated initiation using by of a a the gaslimits multiadsorbent next chromatograph were technique sampling with about and event. a 0.1 ppbv. then flame ionization detector. Thetemperature, detection RH, pressure, wind speed,and wind precipitation) direction, were measured levels continuously of fromPPN UV-A the (at and same Yufa, UV-B meteorological height light, observation as stoppedin were on PAN the and 13 following September). time Any series breakpoints were due to power outages or calibration. The method (EPA’s Method TO-15)air specifies in steps passivated for stainlessgraph collecting steel (Shimadzu samples canisters Mini-2) of and with ambient analyzingand flame them evacuated ionization before using detection. being a placed The gas at canisters the chromato- were sampling cleaned sites. lyzer (EC9841 NO/NO Both instruments were dynamicallychemiluminescent NO calibrated using abacher dynamic et calibrator. al., 2007; Sincetracting Winer the the et mixing ratios al., of1981). 1974), NO, the As PAN, and NO a PPN preliminaryprimary from study volatile the into organic total compounds the NO (VOCs), relationships1-butene, some between cis-2-butene, species PAN and (n-butane, and trans-2-butene, propylene) PPN were and measured their with a time resolution of 1 h. and Yufa took place from 15 to 27 August andsitu 3 standard to ozone) 12 was September, also respectively. using measured an (this analyzer stopped (EC9810 on Ozone 11 analyzer,per ECOTECH) September billion with 2006 a by at detection Yufa) volume limit of (ppbv). 1 part NO Overall uncertainty was 15% for PAN and 20% for PPN. The in situ sampling at PKU were observed. The system was also calibrated before and after the in situsampling. Teflon to minimize the lossGaseous of PAN was PAN prepared and directly PPN throughultraviolet and the reaction to (UV) of prevent CH light heterogeneous formation. concentration (wavelength, of 285 nm). PAN ranges fromambient It couple PAN of is concentration. pptv diluted to PPNthen for ca. volatilized. was calibration. 15 synthesized These ppbv to in preparationsresponse The cover were liquid to the used PPN diluted phase range for was in 0.83 of instrumentto when laboratory calibration. 1.0. compared and to The The the ECD’s value PANwas response, of performed which 0.83 was before is set and from equal after Roberts’ the studies measurement (1998, period, 2003a, and b, no 2007). significant Calibration changes diaphragm pump and sampledsix-port by rotary a valve (VICI Teflon Valco samplerECD Instruments used Co. at was Inc., 5-min a Houston, intervals TX)were automatically. using 5 The and a 10 Teflon parts per trillion by volume (pptv), respectively, with uncertainties (2 nal diameter (ID) 0.53 mm,aluminum 2 block, m; which J&W was Scientific, thermoelectricallydecomposition Folsom, cooled CA) of to was 15 PAN wrapped and aroundto an PPN. 15 During sample15 standard loading, cubic centimeters the per oveninjections minute was (sccm) were and also made 30 sccm, cooled fromethylene, respectively. a Whole-air commercially named 2-mL NEOFLON sampleinch. PFA) loop with composed Ambient an outside of air diameter a at (OD) 1 PFA of (Polytetrafluoro standard 1/8 liter per minute (slpm) was drawn continuously by a Ambient PAN and PPNtor were (GC-ECD). measured Detailed usinget a information al. gas about (2000). column-electron this captureOceanic instrument Briefly, and detec- can the Atmospheric Administration be detector (NOAA). was found The manufactured in column by (model Williams the DB-210, inter- United States National 2.2 Equipment 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . 1 − ) for 2 10 -gassing × 0.62) and ff ( 3 ± ects on vege- ff were observed at 3 on that day was much higher 3 0.73) and 0.13–0.26 (average c Authority of Beijing Municipal ± ffi ; the PAN concentration was consis- 3 fluctuations followed their usual pattern. (15%). PAN concentrations over 10 ppbv 3 3 8180 8179 ects of wind on PAN and PPN followed similar patterns at ects of PANs and their potential damaging e ects of wind direction and wind speed on pollutants, wind ff ff 0.14). At Yufa, the maximum ratio of PAN to PPN and PAN ff ± usion of pollution), Beijing is at risk for increasing pollution levels. In ff ) ranged from 4.99–7.25 (average 6.04 2 10 VOCs). According to information from the Tra × c to photochemical pollution. 0.04). PAN and PPN were lower than O ( + ffi ney et al., 1999). As shown in Fig. 3, higher concentrations of PAN and PPN ± 3 x ff With increasing economic development and urbanization, and given the geographi- As shown in Fig. 3, the e In this study, we analyzed relationships between PAN and PPN with their major VOC During the sampling period, the maximum concentrations of PAN and PPN at PKU As shown in Fig. 2c, when comparing the statistical parameters of PAN, PPN and At PKU, the maximum concentration ratio of PAN to PPN and PAN to O precursors. Because propylene (Chang and Tso, 1994; Kleindienst, 1994) and total cal terrain (the city isimpede surrounded the on di the west,order north, to and characterize northeast the byroses e mountains were that plotted as shown in Fig. 3. both sites. Higher mixingwind ratios directions. of Pollution PAN became and serious PPN when mainly the related wind to speed south was or less southwest than 4 m s Concern about the health e tation prompted the World Health5 Organization ppbv (WHO) over to 8 h set for anceed PANs air (WHO, this 1987). quality guideline; guideline however, During extensive of our attentionof study should tra period, be focused PAN levels on did the not contribution ex- and 1970s (70 ppbv) (Grosjean(Ga et al., 2001)were and generally associated from with Mexico southerlynation. City winds, which in The are 1997 conducive number (34 to of(NO ppbv) pollutant vehicles stag- in BeijingPublic continues Security, to Beijing increase, is so experiencing370 000 does a motor o rapid vehicles increase werethe in put end vehicle of into numbers. 2006, use, the In causing total 2006, number a of net motor vehicles increase in of Beijing 287 had 000, reached and 2.45 million. by PPN measured in thesured summer at PKU of in 20062.49 the ppbv were summer and about of that 3 2005, ofhad times when PPN increased the higher was in maximum than 0.51 2006still concentration those ppbv. compared much of mea- with In PAN lower was 2005. urban than Beijing, those Levels PAN recorded of and from PANs PPN Los pollution pollution Angeles, in California, Beijing during are the 1960s were observed for the first time in Beijing. The maximum concentrations of PAN and were in 2005, but(158%), were otherwise followed higher by in PPN 2006. (118%) PAN and showed the O greatest increase than the levels regularlydiscrepancies observed, did up occur to on 114 somePPN ppbv days, (see showed such Fig. no as 2). at diurnalThis PKU variation, However, is on occasional while discussed 20 August, O inmidnight when Sect. on PAN 19, and 3.2. 22, 24 Tiny and peaks 25 August for at PAN, PKUozone, PPN, and we and 7 found and O that 12(Wang levels September and of Zhang, at PAN 2007). Yufa. and Ozone PPN levels were were lower in higher the in first 2006 quartile of than 2006 those than they in 2005 tently higher than thatsurements of taken PPN. from These other findingsCape, places are 2005; (Grosjean, in Roberts 2003; accord et Lee with al., et PAN 2007; and al., Zhang PPN et 2008; mea- al., McFadyenboth 2009). and occurred on 24 Augustand (see PPN Fig. were 2). on At 6 Yufa, September, the and maximum the concentrations peak of level PAN of O PAN, PPN, and ozone1973, (in Taylor Fig. 1969). 2a PAN and andsecondary O3 b) pollutants. are basically Major highly statistical correlated follow data in the are aged same shown air in trends masses Table (Stephens as 2. each both day during are this short0.25–0.81 campaign (average ranged 0.51 from 4.70–7.52 (averageto 5.64 O 0.20 3.1 Time series of PAN andPAN PPN and PPN were measuredfrom at 3 PKU to from 12 15 September August to 2006, 27 and August the 2006 results and are at shown Yufa in Fig. 2. The variations in 3 Results and discussion 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ney et al., ff 3678). Williams = n , which originates al- · erent from those mea- 3 98, ff . 0 CO = 2 2 R CH 3 3 135 pptv, ( + 8182 8181 ) was heavy, resulting in the afternoon peak. At x 5.60[PPN] = , which originates from both biological and anthropogenic sources, c. Although sunlight is not particularly strong by the mid-afternoon, · 3 ffi CO 3 ) increased, leading to gradual increases in PAN and PPN concentrations, which x PAN and its analogues have relatively similar chemical properties. Their thermal At Yufa, PAN and PPN concentrations increased rapidly from 08:30 through photo- The daytime peak at PKU was similar to that measured at Yufa. Strictly, there were When compared with other sites, PAN and PPN pollution at PKU is not particularly PKU is shown in Fig.et 6a al. [PAN] (1998) and Roberts et al. (1998b, 2001) demonstrated that when the regression The VOC precursors ofators PAN of were CH unlikewhereas those PPN of precursors PPN. aremost PAN those exclusively precursors that from are anthropogenic generate gener- sources2001; CH (Grosjean Roberts et et al.,concentration 1993, al., ratios 2001; 2004). of Grosjean, PPN to The PAN (Roberts main et VOC al., sources 2004). stabilities can are be also inferred basically based the on same. the Linear regression between PAN and PPN at reversed to approach a secondsun peak had between set, 18:00 PAN andwas and 21:00. a PPN slight After concentrations increase 20:30 gradually to when declined. a the short At peak,3.3 before about a 00:00, gradual there drop Correlations to between early PAN, morning. PPN and O sured at Yufa. The afternoonwork-related peaks tra for PAN and PPNemission were of probably pollutants due (such toYufa, which the as is heavy suburban, NO vehicle contributions towere pollution at were the less urban important site than they of PKU. chemical reaction, and they reachedAfter their this daytime first maxima peak, between PAN and 12:00 PPN and concentrations 15:00. initially fell until the downward trend their minima at about midnight (see Fig. 5). two peaks during thecurred day, after but 15:00, the as secondserved shown for peak in PAN and was Fig. PPN, not before 5a and clear. and after b. 00:00, The which peak During were di always the oc- night, two peaks were ob- reached their maximum levels during the afternoon, thereafter slowly decreasing to and the morning rush hour,NO precursors for PAN and PPN formation (such as VOCs and 3.2 Diurnal variations in PAN and PPN Diurnal variations in PANreported and from PPN other levels sites worldwide (as1998; (Corkum Lee shown et et in al., al., Fig. 1986; 2008;et Evmorfopoulou 5) McFadyen al., and and were 1993; Glavas, Cape, similar Roberts 2005;Stephens, et to Penkett 1973; et al., those Tsanibazaca al., et 1998b, 1975; al., 2007; 1988; Rappengluck Schrimpf Williams et and Grosjean, al., 1990). 1998; After Shepson sunrise et al., 1992; Scotia, North Atlantic. ZhangWaliguan et may al. be influenced (2009) by demonstrated LanzhouCharleston, that and South PAN other mixing Carolina, surrounding also ratios areas. measured at Aback relatively cruise Mt. high trajectory, around levels it of was PAN pollution. demonstratedof With PAN that pollution mainland at transportation sea (Rappengluck resulted et high al., levels 2003, 2004; Roberts et al., 2007). worldwide. High mixingPaulo, ratios and some mainly Asian occurinfluenced cities, by in surrounding which Mexico areas. are City, Currentthe levels undergoing Santiago maxima of rapid PAN de of pollution urbanization 6.8 are Chile, ppbv a orlightly when Sao little polluted. are comapred higher to being than PAN that pollutionlevels in at of 1990s. PAN the recorded The Yufa from suburban siterecorded Yufa Mt. site was from Waliguan was not Lanzhou. in much PAN China,magnitude concentrations higher and higher at than than it this those background was recorded background even from site a lower background were than site an levels at Chebogue order Point, of Nova 1999; Kleindienst, 1994), accountedmation, for a an time important series of proportion PANplotted and of in PPN PAN Fig. with and propylene 4, PPN and showing total-butene for- negative at correlation. PKU Site was high, but the overall pollution levels in Asia are high relative to those of other regions butene, including n-butane, trans-2-butene, 1-butene, and cis-2-butene (Ga 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | → 59, are and . 2 CO, 3 3 0 x O 3400); = + produc- · = 2 3 mainly re- n R 3 65, was not signif- . ect of AHCs at 0 ff also comes pri- 3 4.92, ( = 3 + 1994). 2 , PAN, and PPN at 3 = R precursors (NO n 3 ) generated by vehicle 2 51, . 3306). At Yufa, the corre- 6.88, ( 0 = + = n 2 erences, and has therefore been R ff 56, ratios (Tuazon et al., 1991). . 42.94[PAN(ppbv)] 2 0 (NO and NO = = 8.95, ( x 2 3459). 2841). Ratios of PAN to PPN ranged from + R were well correlated during the day, but the (PAN). In the removal process, O = = 2 3 cients were 0.65 and 0.59 at PKU and Yufa, n n 8184 8183 ffi (ppbv)] 18.87[PAN(ppbv)] 3 95, 93, . . = 11.64, ( 0 0 + = = 2 2 R R C(O)OONO 3 (ppbv)] 3 CH 234.09[PPN (ppbv)] → 2 = 2 2 19 pptv, ( 77 pptv, ( − + NO NO NO O + + + + · (ppbv)] , 9 9.00[PPN (ppbv)] 3 OH RO · , PAN, and PPN was [O NO concentration by directly or indirectly adsorbing O 3 3 = → → 3 O → 4.98[PPN] 5.83[PPN] → C(O)OO NO hv NO = = 2 erent chemical formation and removal processes. During the day, net O 3 , which also has external input from the atmospheric boundary layer exchange. + + + 3 ff C(O)OO O (ppbv)] 2205); [O 2 2 2 3 3 Heterogeneous reactions take place on aerosol surfaces, which can reduce tropo- The relationship between ozone and PAN is discussed separately by daytime (08:00– VOC precursors for PAN can transfer to aldehyde vinyl substancesCH with CH Based on our measurements, the correlation between PAN and O Di PAN is a product of photochemical smog, and tropospheric O The linear regression between PAN and PPN at Yufa is shown in Fig. 6b: + = omitted from this discussion.correlation PAN and was O much weaker at night. This is mainly because PAN (PPN) and O spheric O VOCs) (Jia et al., 2006).of O In addition, thePAN stability and of PAN PPN and have PPNactivities. no is weaker natural than emission that sources and are only20:00) generated and nighttime by (20:00–08:00). human to The that relationship of of PAN with PPN ozone, with except ozone for was magnitude similar di CH acts with NO, whereaswhich PAN is is determined mainly by removed temperature by and thermal NO/NO decomposition, the rate of HO RO NO O such as acetaldehyde and acrylamide. The subsequent reaction is CH3O icant (see Fig. 7).respectively. The The main correlation reasons for coe this finding can be summarizedtion as occurs follows: through the following reactions (Roberts et al., 1995): marily from photochemicaland reactions industrial emissions. ofcorrelated NO Therefore, (Schrimpf variations in et PAN al.,PKU and was 1998). ozone described tend as to The [O [O be linear closely regression forlation O for O n tributed partly. Yufa ismany located vehicles in in the suburbs thea of area, great Beijing, impact it and on neighbors althoughprocesses. pollution the there at were Jingkai the not Highway site, Express. and AHCs Vehicles still had dominated local photochemical local photochemical processes.ing PAN 13–28 and August PPN 2005, measurements[PAN] and were the also correlation taken between dur- PAN and PPN was[PAN] found to be 4.99 to 7.25 and werecesses considerably at lower Yufa were than 7.4, alsoYufa was indicating mainly that controlled weaker photochemical by than pro- AHCs. it was However, the at e PKU, and biological hydrocarbons (BHCs) also con- enced by anthropogenic hydrocarbons (AHCs).centage A of steeper slope AHCs indicated participating thatet in the al. photochemical per- reactions (1998a, wasranging 2001) much from and higher. 5.8 Williams Roberts tothe et 7.4 ratios al. reflected of (1998) PAN AHC-dominated to indicated photochemical PPN that reactions. ranged ratios from At of 4.70 PKU, to PAN 7.52, to suggesting PPN that AHCs dominated slope was less than 7.4, photochemical processes in the area were primarily influ- 5 5 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (5) (6) (7) (8) (1) (2) (3) (4) ], respec- 2 . The rate of 2 : 2 28 (Tuazon et al., 1991) . ) and NO 0 · ± 95 . 1 C(O)OO = 3 C, at standard atmospheric pressure, ◦ PAN − 1 /k 8186 8185 2 9 . . 2 2 2 PAN (Kirchner et al., 1999). Equation (5) can be sim- 0 8 ) ) − 1 2 NO NO − k /T /T cient for photochemical reactions such as PAN and s + + , · · ffi M 1 /T − + ] s 2 12(300 /T 28(300 ] 13940 C(O)OONO 2 ected by light, especially by the short-wave bands found dur- 3 C(O)O PPN − [NO − − 3 ff 2 1 e C(O)OO = E E are the reaction constants for [PAN], [NO], and [NO [NO] 3 k [NO ] 13573 [NO] CH 16 4 M 2 4 CH − + 70 00 CO PPN PPN k . . PPN k + e − CH 10 → − − erent slopes. Since PAN and PPN are very similar at the structural + PAN vary from each other in their decomposition mechanisms (Roberts 2 2 95[NO] [NO 2 1 4 · → . k ff 2 − 16 k × k 1 3 k 3 4 → [NO] and k + 2 10 + NO 2 94 , NO NO . 1 CH 2 k 1 × + + + 7 k · · = = = , = 52 · → 1 . k C(O)OO: 2 5 PPN = H − dt dt dt 6 2 C(O)OO k 5 C(O)OO C(O)OO C(O)O C(O)OONO ln[PAN] ln[PAN] ln[PPN] PAN 3 3 3 3 erence in rate constants. H d d d Based on Reactions (R2–R4), the thermal decomposition rate of PAN mainly de- PAN was generated by acetyl-peroxynitrite (CH PAN and PPN were strongly correlated both during the day and at night (see Fig. 8), − ff 2 4 − − − creased rapidly when thePAN temperature sink increased. pathways (Talukdar et This al., was 1995). the most important ofpended the on temperaturethermal and decomposition on can be the calculated concentration as follows: ratio of NO to NO Reaction (R4) was considerably active at room temperature, and the reaction rate in- In which, tively. When temperature rangedk from 10–40 and plified as CH For C C Low pressure limit: 9 Hgh pressure limit: 7 thermal decomposition. Thermaland PPN decomposition are is removed the from the main atmosphere. pathway by which PAN with only slightly di level, both their reactiondi and decomposition mechanisms are alike, with only3.4 a minor Thermal decomposition of PAN andPAN PPN and PPN have three main sink pathways: dry deposition, surface reaction, and photochemical reaction e ing the day. At night,ozone formation. light is During nighttime, insu decompositionPAN (PPN) (sink) becomes and very O important,et and al., 1995). primary integral parts of photochemical smog, which is generated to a large extent by Acetyl-peroxynitrite can be generated byaction a (R1), broad leading species to ofthe organic reaction PAN formation, of compounds. acetyl-peroxynitrite was Re- with competitive NO: withCH Reaction (R2), showing CH Thermal decomposition of PAN in the atmosphere wasCH also important: 5 5 10 15 15 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 −   (9) 2 (10) (11) (12) (13) C at http: ! ) ◦ erent ff RT PV ( × 23 37.1 2 . 10 0 × ) − 02 T . 300 6 ( × C 9 ◦ . 12 8 − ) 10 T × 300 and IUPAC, ( were very di 70 . 28 7 − 10 × C(O)OO and NO are ) PPN 00 5 . − 9 1 H /T lg was smaller for PAN than 2

/k 2 + 1 T 340   /k 6 0.096 at Yufa site. e PPN 1 . − 0 k × ± 2 exp(340 × 12 k ) ) − × RT RT PV PV ( ( 10 × × 12 × 23 23 − 10 10 70 T E . × × 340 6 02 02 e . . 70 cient at PKU was higher than that at Yufa, 6 6 . × × × 8188 8187 ffi 9 9 . . 8 8 ) ) 12 3 − − T T exp(14000) 300 300 ( ( OO;6 × 2 10 28 28 1 − − − ×  29 10 10 2 CH × × −  3 ] 70 00 00 . . . E M C at Yufa, which was within the reference referred range 9 9 [ ,T ◦ 6 × + molec cm ,T ∞ CH 2 2 ;9 0.03 at PKU site and 3.22 , . . 0 k 0 0 = ) k 2 cient at Yufa was lower than that at PKU. For PPN, the slope ) ) + ± lg T T ffi 2 300 300  NO ( ( 98). The ratio between PAN and PPN ranged from 4.6 to 7.4, RT NO PV http://jpldataeval.jpl.nasa.gov/download.html + . − 12 12 1 − − 0 + NO C–29.8  c 10 10 ◦ 23( = − F × × ] + 70 70 ] . . 93 7 7 M NO . E [ M 0 [ = + ,T 02 C. Thermal decomposition of PAN and PPN can therefore be calculated 2 0 ,T = C(O)OO . ◦ C2H5C(O)OO 0 k 5 NO 6 2 NO k − − ,k H + R = ,T 2 ,T erence between the two sites. When comparing PAN thermal loss versus PPN d ∞ C ff C–40 ∞ k N ◦ C(O)OO = k 5 = cient ( ] H = : 0.6, see JPL06 PAN and PPN thermal decomposition was calculated (see Table 3), and the results High correlations in the percentages of thermal decomposition of PAN and PPN are Unlike levels of PAN at the two sites, the ratiosDuring of the measurement period, the temperature ranged from 18.7 2 C2H5C(O)OO r ffi C2H5C(O)OO c M k k the two sites were broadlypercentage the losses than same; did however, for the PPN, suburban site. the urban site showed higher PPN levels had increased inmajor 2006. VOCs Inverse were correlations found. betweenwith PAN, the PPN, Diurnal characteristics and variations of their in photochemicalPPN reactions. the levels Correlation appeared levels showed of toe that PAN follow PAN and and generally PPN similar accorded indicating trends, that with the main a contributorsthermal strong to decomposition correlation was VOCs calculated, at co- and bothan the sites results important were confirmed AHCs. impact that thermal PAN on and loss their has PPN atmospheric lifetimes. The percentages of PAN loss at of PAN and the adding of it with correspding ambient concentration. 4 Conclusions When compared with data gathered from PKU in 2005, it was found that both PAN and at Yufa was larger thanlittle that di at PKU andthermal showed poor loss, correlation. it Forindicating was PAN, there that found was plots that at Yufa the were more coe disturbed. indicate that thermal losspercentages has of PAN an loss at important the impact twoloss sites was on are higher roughly their than the atmospheric suburban. same; TDPAN however, lifetime. for and PPN, SUM The urban represent the thermal decomposition shown in Fig. 9a andloss b. of The PPN slope was wasfor more less PPN; than than thus, that 1, NO of indicating wasThe PAN. that more The absolute the important ratio relative values in of thermal of theand thermal PAN d), and loss although PPN of the PPN thermal coe than loss in were that also of correlated PAN. (see Fig. 9c k [ The equations for the rate constant of Reaction (R8) are shown as follows: PPN thermal decompositionshown in and Eqs. the (11) and reaction (12) betweenPPN C C //www.iupac-kinetic.ch.cam.ac.uk/ Therefore F of 10 according to the relevant equations. Namely, at two sites, namely 2.80 PKU and from 10.1 5 5 25 15 20 10 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | M-Reversible- + 2 NO + 2 doi:10.5194/acp-7-3103- C(O)O 3 ´ elec, P.: Tropospheric ozone cli- , and other pollutants is recom- 3 ´ ed ,O 2 ect of Peroxyacetyl Nitrate on the Initiation of ff 8190 8189 , 2008. ect of Peroxyacetyl Nitrate on Plants – Photoreductive Reac- ff This work was part of CAREBEIJING 2006 (Campaign of Atmospheric M between 248-K and 393-K and between 30-Torr and 760-Torr, J. Phys. + doi:10.5194/acp-8-1-2008 2 N0 2 , 2007. C(O)O 2 ney, J. S., Marley, N. A., Cunningham, M. M., and Doskey, P. V.: Measurements of peroxy- ff nitrate during SCOS97-NARSTO, Environ. Sci. Technol., 35, 4007–4014, 2001. ypropionyl nitrate in Porto Alegre, Brazil, Atmos. Environ., 36, 2405–2419, 2002. NARSTO, Atmos. Environ., 37, S221–S238, 2003. organics .3. Peroxyacetyl nitrate and peroxypropionylTechnol., 30, nitrate in 2704–2714, Los 1996. Angeles air, Environ. Sci. of Papers of the American Chemical Society, 221, U452–U453, 2001. in Athens, Greece, Atmos. Environ., 35, 5467–5475, 2001. – Atmospheric Oxidation of Cis-3-Hexen-1-Ol, Environ. Sci. 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F.: KineticCh and Theoretical-StudiesChem., of 95, 3594–3600, the 1991. Reactions Ch Georgia: Comparison and analysis ofAir ambient Waste data Manage., for 49, suburban 177–184, and 1999. downtown locations, J. episode occurred in Beijing,2007 Atmos. Chem. Phys., 7, 3103–3114, Long-term measurement of PAN, PPN, NO, NO Guttikunda, S. K., Tang, Y. H., Carmichael, G. R., Kurata, G., Pan, L., Streets, D. G., Woo, J. Grosjean, E., Grosjean, D., and Woodhouse, L.Grosjean, F.: E., Peroxyacetyl Grosjean, nitrate D., Woodhouse, and L. peroxypropionyl F., and Yang, Y. J.: Peroxyacetyl nitrate and perox- Grosjean, E., Grosjean, D., Fraser, M. P., and Cass, G. R.: Air quality model evaluation data for Grosjean, D.: Ambient PAN and PPN in southern California from 1960 to the SCOS97- Grosjean, D.: Long-term trends in ambient peroxyacetyl nitrate in southern California, Abstracts Grosjean, D., Williams, E. L., and Grosjean, E.: A Biogenic Precursor of Peroxypropionyl Nitrate Glavas, S. and Moschonas, N.: Determination of PAN, PPN, PnBN and selected pentyl nitrates Ga Evmorfopoulou, E. and Glavas, S.: Formation of nitrogenous compounds in the photooxidation Dugger, W. M. and Ting, I. P.: E Dugger, W. M., Klein,, W. H. Taylor, O. C., and Shropshire, W.: Action Spectrum of Peroxyacetyl Ding, A. J., Wang, T., Thouret, V., Cammas, J.-P., and N Duan, J. C., Tan, J. H., Yang, L., Wu, S,. and Hao, J. M.: Concentration, sources and ozone Corkum, R., Giesbrecht, W. W., Bardsley, T., and Cherniak, E. A.: Peroxyacetyl Nitrate (PAN) Chang, S. Y. and Tso, T. L.: Measurement of the Taiwan Ambient Trace Gas Concentration Darley, E. F., Stephens, E. R., and Kettner, K. A.: Analysis of peroxyacetyl nitrates by gas Carter, W. P. L., Winer, A. M., and Pitts, J. N.: E Bridier, I., Caralp, F., Loirat, H., Lesclaux, R., Veyret, B., Becker, K. H., Reimer, A., and Zabel, Aneja, V. P., Hartsell, B. E., Kim, D. S., and Grosjean, D.: Peroxyacetyl nitrate in Atlanta, An, X., Zhu, T., Wang, Z., Li, C., and Wang, Y.: A modeling analysis of a heavy air pollution Acknowledgements. Researches in Beijing and surrounding areasof in 2006) Science and and was supported Technology by (HB200504-6,the the HB200504-2), Beijing Beijing Council Municipal the Government NaturalPlan (8072014) Science (863 and Fund Project, the Project 2006AA06A301). National of State It High Joint was Technology Laboratory also Development of supported Environmental by Simulation the and special Control, fund Peking provided University. by the References mended to further increase understanding ofits the characteristics. photochemical pollution Based in on Beijinggies on-line and can monitoring be data, implemented reasonable topollution. methods improve and air strate- quality and curb the spread of photochemical 5 5 30 25 20 15 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , doi:10.1029/2004JD004921 , 2002. 8191 8192 doi:10.1029/2001jd000947 , 2004. Berlin, Germany, during nighttime on 7 August 1998, Atmos. Environ., 38,Brice, 6125–6134, 2004. K. A., Parrish,M.: D. Relationships D., between Fehsenfeld, PanRes.-Atmos., F. and 100, C., Ozone 22821–22830, Buhr, at 1995. Sites M. in P., Meagher, Eastern J. 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K., Poon, C. N., Wu, W. S., Gao, J., Zuo, Zhang, J. B. and Tang, X. Y.: , Atmospheric PAN measurements and the formation of PAN in Xu, J., Zhang, Y. H., Fu, J. S., Zheng, S. Q., and Wang, W.: Process analysis of typical sum- Winer, A. M., Peters, J. W., Smith, J. P., and Pitts, J. N.: Response of commercial chemilu- Williams, J., Roberts, J. M., Fehsenfeld, F. C., Bertman, S. B., Buhr, M. P.,Goldan, P.D., Hubler, Williams, E. L. and Grosjean, D.: Peroxypropionyl Nitrate at a Southern California Mountain Williams, E. L. and Grosjean, D.: Southern California Air-Quality Study – Peroxyacetyl Nitrate, Teklemariam, T. A. and Sparks, J. P.: Gaseous fluxes of peroxyacetyl nitrate (PAN) into plant WHO: WHO Air Quality Guideline for Europe, WHO Regional O Wang, B. and Zhang, J.: Monitoring and Analysis of PAN and PPN in the Air of Beijing During Talukdar, R. K., Burkholder, J. B., Schmoltner, A. M., Roberts, J. M., Wilson, R. R., andTaylor, O. C.: Rav- Importance of peroxyacetyl nitrate (PAN) as a phytotoxic air pollutant, J. Air Pollut. Sun, E. J. and Huang, M. H.: Detection of Peroxyacetyl Nitrate at Phytotoxic Level and Its Tuazon, E. C., Carter, W. P. L., and Atkinson, R.: Thermal Decomposition of Peroxyacetyl Steinbacher, M., C. Zellweger, B. Schwarzenbach, S. Bugmann, B. Buchmann, C. Ordonez, Stephens, E. R.: Analysis of an Important Air Pollutant – Peroxyacetyl Nitrate, J. Chemi. Edu- Tsanibazaca, E., Glavas, S. and Gusten, H.: Peroxyacetyl Nitrate (PAN) Concentrations in Temple, P.J. and Taylor, O. C.: Worldwide ambient measurements of peroxyacetyl nitrate (PAN) Singh, H. B., Ohara, D., Herlth, D., Bradshaw, J. D., Sandholm, S. T., Gregory, G. L., Sachse, Singh, H. B., Herlth, D., Ohara, D., Zahnle, K., Bradshaw, J. D., Sandholm, S. T., Talbot, R., Singh, H. B. and Salas, L. J.: Measurements of Peroxyacetyl Nitrate (PAN) and Peroxypropionyl Singh, H. B. and Hanst, P. L.: Peroxyacetyl Nitrate (PAN) in the Unpolluted Atmosphere – an Shepson, P.B., Hastie, D. R., So, K. W., and Schi 5 5 30 25 20 15 10 30 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | range ney et al. (1999) ff 6 Darley et al. (1963) Ozone (ppbv) ∼ 0.005 Roberts et al. (2002) 0.004 Roberts et al. (2007) < < 3400) 2234) = = n n 34.59( 31.43 22.9( 39.2–140.4 28.6 39.1–114.8 Average Median Daily max. (max/aver.) (max/aver.) range . PPN (ppbv) 3 8196 8195 3239) 2462) = = n n Average Median0.24 Daily max. ( 0.10 0.15( 0.16–1.95 0.08 0.13–0.41 October 2002December 2002January 20031 August–31 December 1967August 1968August 1976August 1980 3.8/1.8 9.8/5.3 581 July –16 October 1997 22/6.4 – 28/5.9 – – 20/3.0 Taylor (1969) 22/5.6 4.8/0.880 – 0.72/0.25 – – – Temple and Taylor (1983) urban Several days in May and June 1990 6.8 – Zhang and Tang (1994) range 3740) 2673) Comparison of PAN and PPN levels measured in this study with those measured in = = Statistical data for PAN, PPN, and O n n ( ( Average Median Daily max. PKU 1.34Yufa 0.60 0.91 1.21–11.22 0.50 0.68–2.51 Site PAN (ppbv) Azusa, California urban 28 August–11 September 1993 1.46/0.47 Grosjean et al. (1996, 2001) Riverside, CaliforniaLos Angeles, CaliforniaPorto Alegre, BrazilMexico City, MexicoSimi urban Valley, CaliforniaYufa, Beijing, ChinaLanzhou, ChinaLa Vergne Tennessee Lack dataLa Porte urban Airport, Houston, TexasCornelia Fort Air Park, Tennessee urban urban 9–21 April 1979 urban May 1996–March suburban 1997 suburban February–March 1997 suburban August–September 2000 suburban 14 June–14 July July 18–October 3–12 16, September 1997 suburban 2006 June–July 1995 23 June–17 July 2006 50 2.7/0.72 6.67 3.0/0.608 34 6.5 2.50/0.60 2.51/0.674 0.28/0.13 Aneja et 0.43/ al. – 0.41/0.09 9.13/0.76 (1999) 2.14/0.48 Singh This – and work Hanst (1981) Grosjean et al. – (2002) – 0.32/0.005 Ga Roberts Nouaime et et al. al. (2003) (1998) – Zhang et al. (2009) SitePKU, Beijing, ChinaSeoul Metropolitan area, KoreaTaipei, ChinaHouston, TexasAthens, GreeceSantiago, Chile urban urban May to July, 2004 and 2005 Type 15–27 August 2006 urban urban urban Date urban 10.4/0.8 July 2000 1992–April 1993 2001 September 2002 11.22/1.41 – 1.95/0.24 Lee et This al. study (2008) 27 PANppbv 3.9/2.8 PPN ppbv Reference – 14 6.6 Sun and Huang (1995) – Rubio et al. (2005) – – Roberts et al. (2002) Glavas and Moschonas (2001) Mt. Waliguan, ChinaChebogue Point, Nova Scotia, NorthCharleston, Atlantic South Carolina Background August–September 1993 0.325/0.049 marine Background 0.089/0.009 22 July–16 August Roberts 2006 et al. (1998b) 12 July–10 August 2002 1.4/0.44 2.79/0.36 0.387/ – Zhang et al. (2009) Table 2. Notes: At PKU, measured PANthe was always detection above the limit detection (5than limit, pptv). but the the detection At minimum limit. Yufa, PPN the was sometimes minimum lower level than of PAN was 0.07 ppbv, and for PPN, the minimum was lower Table 1. other regions (ppbv). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1899, =

n Yufa uancun Street uancun gg m Zhon 2096; PPN: = 0.58 10.04 pptv 0.08 – 4 pptv (5 min resolution) mnasiu y n 29.2% 0.2% 9.2% erent sampling sizes between the 15.24% – 3.5% Univ G Univ ff g Pekin PAN: Max (ppbv) Min Average Measurement Site Measurement

Site 1476, = 38 n 8198 8197 5 pptv 0.13 5 pptv 0.03 < < PKU 1575; PPN: = n 34.1%42.2% 0.1% – 10.8% 9.1% PAN: Max (ppbv) Min Average Figure 1. Geographical locations of the sampling sites in Beijing Beijing in sites sampling the of locations 1. Geographical Figure ambient ambient Measurement Site Site Measurement

Summary of data for TDPAN and TDPAN/SUM. Figures Figures Geographical locations of the sampling sites in Beijing. 1 2 3 4 Thermal decomposition (10 min resolution) TDPAN (ppbv) 1.37 TDPPN (ppbv)TDPAN/PAN 0.31 TDPPN/PPN Fig. 1. Notes: PAN and PPN dataat were each synchronized site with (PKU: thetwo 10 time sites. min; resolution When Yufa: of calculating 5 meteorological thermal min) data loss, for and 10 thermal min conventional data loss gases were calculation, used resulting for in both sites. di Table 3. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | were (d)

and (c)

mixing ratios were plotted. plotted. were ratios mixing 3 comparisons of PAN, PPN, and ozone ozone and PPN, PAN, of comparisons , the higher vertical bar represents the 3rd 39 (c)

41 8200 8199 mixing ratios were plotted. Measurements of PAN [2007]. [2007]. 3 Wang and Zhang and Zhang Wang Figure 2. Time series and inter-annual Time Figure 2. Figure 3. Wind roses for PAN and PPN pollution pollution and PPN PAN roses for Wind 3. Figure Measurements of PAN and PPN were also taken in the summer of 2005 between August 15 and 29. Details Details 29. and 15 August between of 2005 summer the in taken also were PPN and PAN of Measurements from can be obtained In orderdisplay to all information Figure. in only 2c, one-tenththe of O

Notes: 1. , only one-tenth of the O 5 6 1 2 3 4 7 (c) (c) (d) (d) (c) (a) (b) (b) (a) Wind roses for PAN and PPN pollution Notes: At Yufa, the meteorological data was Time series and inter-annual comparisons of PAN, PPN, and ozone. In order to display Fig. 3. taken up to 10 September; therefore the values of PAN and PPN plotted in also consistent with the wind data input. Fig. 2. all information and PPN werebe also obtained taken from in Wang the and summer Zhang of (2007). 2005 In between 15 and 29 August. Details can quartile, and theindicates lower the vertical average, and bar the lower represents edge the of box 1st indicates quartile. the median. The upper edge of the box Notes: At Yufa, the meteorological data was taken up to September 10; therefore the values of PAN and PPN and PPN of PAN values the therefore 10; to September up taken was data meteorological the Yufa, At Notes: input. data wind the with consistent were also d) 3 (c and in Figure. plotted 1 2 5 6 7 8 9 3 4 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

42 8202 8201 43 s-2-butene, 1-butene, and cis-2-butene cis-2-butene and 1-butene, s-2-butene, Figure 5. Diurnal variations in PAN and PPN PPN and in PAN variations 5. Diurnal Figure Figure 4. PAN and PPN with their major VOC precursors at PKU Site Site at PKU precursors VOC major their with PPN and 4. PAN Figure quartile, respectively. respectively. quartile, st Diurnal variations in PAN and PPN. Bold black lines show the median at the same PAN and PPN with their major VOC precursors at PKU Site. Butane includes n-butane, quartile and 1 quartile Fig. 5. time on all measurementrespectively. days. Upper and lower error bars are 3rd quartile and 1st quartile, Fig. 4. trans-2-butene, 1-butene, and cis-2-butene. rd Notes: butane includes n-butane, tran n-butane, includes butane Notes: Notes: Bold black lines show the median at the same time on all measurement days. Upper and lower error bars error bars lower and Upper days. on all measurement time same at the the median show lines black Bold Notes: are 3 1 2 3 4 4 5 1 2 3 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

44 45 8204 8203 Figure 6. Correlation between PAN and PPN PAN between Figure 6. Correlation Figure 7. Correlation between PAN and ozone and ozone PAN between Figure 7. Correlation (a) (b) (b) (a) Correlation between PAN and ozone. Correlation between PAN and PPN. Fig. 7. Fig. 6. 3 4 1 2 1 2 3 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

3 . 46 3 47 8206 8205 Thermal decomposition of PAN and PPN and PPN of PAN decomposition Thermal

Figure 9. Figure 8. Correlations among PAN, PPN, and O and PPN, PAN, among Correlations 8. Figure 1 2 Thermal decomposition of PAN and PPN. Correlations among PAN, PPN, and O Fig. 9. Fig. 8. 1 2 3