Characteristics of carbonyl compounds in ambient air of Shanghai, China

Ambient carbonyls in urban air in Qinzhou were studied form October 2011 to July 2012 to investigate their distribution characteristics and sources. Acetaldehyde (8.04 ± 9.00 µg/m 3 ), formaldehyde (6.70 ± 6.36 µg/m 3 ) and acetone (2.43 ± 2.81 µg/m 3 ) were three most abundant carbonyls, accounting for ~90% of the seven carbonyls identified. Concentrations of most carbonyls showed significantly higher levels in spring and summer than those in autumn and winter. Seasonal and diurnal variations indicated that formaldehyde and acetaldehyde were related to barbecue emissions and photochemical loss, while solvent usage was responsible for acetone. The average C 1 /C 2 ratio was higher (1.92) in summer than that during other seasons (0.52-1.78), implying the positive impact of photochemical loss or formation; and a significantly lower C 2 /C 3 ratio (2.57) was observed in winter than during other seasons (12.47-52.82), suggesting significant emissions from straw burning and barbecues. Formaldehyde and acetaldehyde were the two major contributors (63-97%) to O 3 formation, particularly in spring and summer.

Section: Concentration Ratiossupporting

confidence: 83%

Section: Concentration Ratiosmentioning

confidence: 88%

Seasonal and Diurnal Characteristics of Carbonyls in Urban Air in Qinzhou, China

Guo

Chen

et al. 2014

“…Over the urban areas, the ratio varies between 1-2 (Feng et al, 2005;Cerón et al, 2007;Huang et al, 2008;Dutta et al, 2009;de M. Ochs et al, 2011), whereas over the rural areas the ratio becomes much higher, ~10 (Shepson et al, 1991;Possanzini et al, 1996). The probable reason for different C1/C2 ratios is the different sources of formaldehyde and acetaldehyde over different areas.…”

Section: Formaldehyde To Acetaldehyde Ratio (C1/c2)mentioning

confidence: 99%

How the Atmosphere over Eastern Himalaya, India is Polluted with Carbonyl Compounds? Temporal Variability and Identification of Sources

Sarkar

Chatterjee

Majumdar

et al. 2017

A study was conducted on atmospheric carbonyl compounds for the first time over a Himalayan atmosphere in India. Samples were collected from a high altitude hill station, Darjeeling (27.01°N, 88.15°E, 2200 masl) during June 2012 to May 2013. Temporal variation, meteorological influence, source apportionment and ozone formation potential etc were studied for acetaldehyde, formaldehyde, acetone, butanaldehyde, propanaldehyde, benzaldehyde, crotonaldehyde, valeraldehyde, isovaleraldehyde, hexanaldehyde, p-tolualdehyde and o-tolualdehyde. High concentration of Acetone (81.6 ± 63.5 µg m -3 ) was observed which could be due to the higher photochemical production from its precursor volatile organic compounds emitted from tea plants and tea processing units. The concentration of acetaldehyde (20.7 ± 47.6 µg m ). Meteorological parameters like temperature and surface reaching solar radiative flux played the major roles for the seasonal variation of the carbonyl concentration over the hill station. The average ratio of formaldehyde to acetaldehyde over Darjeeling was found to be 1.64 ± 1.43 well representing a typical urban atmosphere at this part of Himalaya. Positive matrix factorization model showed that the biogenic emissions from tea plants and vehicular emissions were the major sources of carbonyl compounds over the hill station.

“…And local photochemical conditions are expected to be favorable for atmospheric carbonyls. Photolysis and reactions with OH· and O 3 could change carbonyl distributions in the atmosphere (Atkinson, 2000;Huang et al, 2008;Pang and Lee, 2010;Duan et al, 2012). Among them, reaction with OH· is often the dominant loss process for carbonyls in photochemically polluted air (Atkinson, 2000), which depends on reaction rate constants of carbonyls; for example, the reaction rate constants are 0.98 and 1.58 × 10 11 ·cm 3 ·molecule −1 ·s −1 for formaldehyde and acetaldehyde, respectively.…”

Section: Variations In C 1 /C 2 Concentration Ratiosmentioning

confidence: 99%

Pollution Characteristic of Atmospheric Carbonyls during One Haze Event in Nanning, South China

Guo

Chen

2016

This study was the first to investigate pollution characteristics of atmospheric carbonyls in one haze event (July 17-22, 2012) in Nanning, south China. It was found that (1) acetaldehyde (29.74 ± 6.06 µg m -3 ), formaldehyde (11.20 ± 1.72 µg m -3 ), and acetone (9.18 ± 11.22 µg m -3 ) were the most abundant in haze days, (2) concentrations and O 3 formation potentials of ambient carbonyls in haze days were significantly higher than those on normal days, and (3) visibility and wind speed in haze days were lower than those on normal days, indicating that haze days represented favorable pollution conditions for carbonyls. Diurnal variations of ambient carbonyls in haze days showed a pattern of two peaks occurring in two traffic rush-hour periods due to positive traffic emissions. Average concentration ratio of formaldehyde/acetaldehyde (C 1 /C 2 ) in haze days (0.39 ± 0.10) was slightly lower than that (0.87 ± 0.23) on normal days, and the ratios in two traffic rush-hour periods were close to those in non rush-hour periods, likely implying that traffic emissions might not be a major source for ambient carbonyls. Correlation among formaldehyde, acetaldehyde, acetone, and total carbonyls was good (R 2 = 0.49-0.85) in haze days and excellent (R 2 = 0.80-0.98) on normal days, indicating that the sources of ambient carbonyls in haze days were more complex compared to normal days.