Peroxyacetyl Nitrate and Peroxypropionyl Nitrate during SCOS 97-NARSTO

Abstract

Peroxyacyl nitrates [RC(O)OONO2] play an important role in urban air quality and tropospheric chemistry. They also receive attention as mutagens, phytotoxins, and possible air quality indicators of changes in vehicle fuel composition. Ambient concentrations of PAN (R = CH3) and PPN (R = C2H5) have been measured during summer 1997 at two southern California locations, Azusa (July 14-October 16) and Simi Valley (June 18-October 16). The highest concentrations were 4.8 ppb for PAN and 0.72 ppb for PPN in Azusa and 3.0 ppb for PAN and 0.28 ppb for PPN in Simi Valley. Ambient levels of PAN and PPN during summer 1997 were lower than those measured in the last three studies carried out in southern California in the summers of 1990, 1991, and 1993. Average PPN/PAN concentration ratios were about the same in Azusa (0.142+/-0.025, n = 132) and in Simi Valley (0.135+/-0.028, n = 138). The PPN/PAN ratio measured in Azusa was the same as that measured at that location in 1993 prior to the introduction in 1996 of California Phase 2 reformulated gasoline. Diurnal variations of PAN and PPN generally followed those of ozone with respect to time of day but not with respect to amplitude. The PAN/ozone ratio was lower in Simi Valley than in Azusa, and daytime minima were recorded at both locations. The amount of PAN lost by thermal decomposition accounted for large fractions of the amount of PAN formed (measured + decomposed) during daytime hours at both locations. The amount of PAN lost by thermal decomposition was higher in Azusa and was up to ca. 8.5 ppb, i.e., 4-5 times more than that measured, when afternoon temperatures were ca. 40 degrees C.

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

“…The slope (or the ratio of PPN/PAN) of 0.152 was well within the range (0.135-0.172) reported in polluted areas (Grosjean et al, 1993;Kourtidis et al, 1993;Ridley et al, 1990). The VOCs precursors for PAN have been recognized to be emitted from both anthropogenic and biogenic sources whereas the precursors for PPN (propanal and 1-butene) are predominantly from anthropogenic sources (Grosjean et al, 2001;Roberts et al, 2004). Therefore, the ratio of PPN/PAN has been widely used as an indicator for distinguishing the contribution of anthropogenic hydrocarbons from biogenic hydrocarbons to atmospheric PANs.…”

“…PAN, as the most abundant species among PANs, has been recognized as lachrymators (Altshuller, 1978), mutagens (Shepson et al, 1986), and phytotoxins (Sun and Huang, 1995;Taylor, 1969). PPN as the second largest species among PANs, its atmospheric concentration usually accounts for 4%-20% of PAN (Grosjean et al, 2001(Grosjean et al, , 2002Lee et al, 2008;Zhang et al, 2011), and it is four times phytotoxic (Kleindienst et al, 1990) and five times eye-irritant than that of PAN (Altshuller, 1978). Furthermore, PAN and some of its analogues have been found to 10-50 times toxic to the plant than that of O 3 Marley, 2001a, 2001b;Taylor, 1969).…”

“…PANs are thermal unstable compounds, they are quite stable in the midand upper troposphere under low temperature, and can be transported over long distances from polluted continental regions into the remote areas where they release NOx under high temperature (Honrath et al, 1996;Kondo et al, 1997;Singh et al, 1996), and hence PANs act as important temporary NOx reservoirs and control the photochemical production of O 3 in the remote troposphere (Singh and Hanst, 1981). Due to the particular importance of PANs on atmospheric chemistry, a great number of PANs measurements have been conducted intensively in developed countries, including the urban regions (Grosjean et al, 2001;Marley et al, 2007;Roberts et al, 1995) and remote area (Hartsell et al, 1994;Roberts et al, 2004;Singh et al, 1990Singh et al, , 1992Williams and Grosjean, 1991). However, only few researches involving with PANs are implemented in developing countries of Asia (Lee et al, 2008;Watanabe et al, 1998;Zhang and Tang, 1994;Wang et al, 2010;Zhang et al, 2009).…”

Summertime distributions of peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) in Beijing: Understanding the sources and major sink of PAN

“…We inferred that the much higher O 3 concentration from later afternoon to sunset (around 20:00) on 6 September than those on most other clear days would facilitate conversion of NO to NO 2 and hence greatly restrain PAN thermal decomposition rate (Grosjean et al, 2001). On the other hand, the combination of O 3 and NO 2 both with the relative high concentrations just after sunset possibly favored the formation of NO 3 radicals which would accumulate due to no photolysis.…”

“…The precursors of PAN, leading to the peroxyacetyl (PA) radical, come from both human activity and biogenic emissions, while the precursors of PPN, leading to the peroxypropionyl radical, are predominantly anthropogenic in origin (Grosjean et al, 2001;Roberts et al, 2004). Thus, the ratio of PPN to PAN provides an indicator to evaluate the relative importance of anthropogenic and biogenic VOCs in PANs formation.…”