Diurnal and seasonal cycles of ozone precursors observed from continuous measurement at an urban site in Taiwan

Yang, Kuo-Ching; Ting, Chien Chung; WANG, J; Wingenter, O. W.; Chan, Chang-Chuan

doi:10.1016/j.atmosenv.2004.10.004

Cited by 30 publications

(13 citation statements)

References 26 publications

(31 reference statements)

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“…The morning peak (0.99 ppm at 08.00 h) was lower in magnitude than that of the late evening peak (2.07 ppm at 21.00 h). This two-peak pattern had also been observed in many other sites, such as Changchun, China (Liu et al, 2000); Taichung, Taiwan (Yang et al, 2005); and Bilbao, Spain (Durana et al, 2006). The pattern suggested that the dominant effect in the early morning and late evening was of traffic density, that resulted in the increase of exhaust from vehicles.…”

Section: Concentrationssupporting

confidence: 64%

Trends of Ambient Concentrations of Gaseous Air Pollutants in Almadinah Al Menawwarah, Central Area, Saudi Arabia

Al-Jeelani¹

2012

JKAU Met Sci

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Nitrogen monoxide (NO), nitrogen dioxide (NO2), nitrogen oxides (NOx), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), methane (CH4) and non-methane hydrocarbons (NMHCs) were measured in Almadinah Al Menawwarah, Saudi Arabia. From Ramadan to Hajj season (October, 2005 - January, 2006) daily average concentrations of NO, NO2, NOx, SO2, O3, CO, CH4 and NMHCs, were 0.055, 0.040, 0.095, 0.011, 0.009, 2.82, 3.83 and 1.12 ppm, respectively. The SO2/NOx and SO2/NO2 concentration ratios were 0.12 and 0.28, respectively, suggesting that the mobile emissions are the predominant sources within the study area. The diurnal variations of NO, NO2, NOx, SO2, CO, NMHCs concentrations were similar and showed two daily peaks, in the morning and late evening. These peaks concentrations are linked to traffic density, boundary layer mixing processes and chemical processes in the atmosphere. The diurnal cycles of O3 concentrations revealed a uni-modal peak in the mid-day time. The highest concentrations of the measured pollutants were found in Ramadan and Hajj seasons, due to increasing human activities. Significant positive correlation coefficients (p<0.05) were found between NO, NO2, NOx, NMHCs and CO, and also between SO2 and NO, NO2, NOx, NMHCs and CH4. Significant negative correlation coefficients were found between O3 concentrations and NO2. These results indicate that an increase in O3 level is associated with a drop in the concentration of NO2, CO and NMHCs.

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Section: Concentrationssupporting

confidence: 64%

Trends of Ambient Concentrations of Gaseous Air Pollutants in Almadinah Al Menawwarah, Central Area, Saudi Arabia

Al-Jeelani¹

2012

JKAU Met Sci

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“…Thus, speciated non-methane hydrocarbons (NMHCs) were continuously monitored by photochemical assessment monitoring stations (PAMS) on the island operated by Taiwan Environmental Protection Administration (EPA) since 2002 to provide hourly mixing ratios of 54 C 2 to C 12 species by automated GC with flame ionization detection (FID) (Yang et al, 2005;Chang et al, 2010). The PAMS NMHCs were calibrated every five days by analyzing a gas mixture at sub-ppb levels (Scott Specialty Gas, U.S).…”

Section: Methodsmentioning

confidence: 99%

Revelation of Coupling Biogenic with Anthropogenic Isoprene by Highly Time-Resolved Observations

Hsieh

Ou-Yang

Wang

2017

Aerosol Air Qual. Res.

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Inter-annual variations of atmospheric isoprene in a major metropolis, Taipei, were reported based on a two-year continuous measurements of non-methane hydrocarbons (NMHCs) with an hourly resolution. It is by far the largest dataset ever collected in the urban subtropical environment with thriving vegetation and traffic flows. The dataset revealed the detailed interplay between the two major sources of biogenic and vehicular throughout the year. To separate the vehicular contribution from the biogenic one for the ambient isoprene, ethylene was used as an indicator of traffic emissions. While dramatic surge of isoprene was observed at noontime in hot months with the highest average peak mixing ratio of 1.6 ppbv in August, its abundance decreased to 0.2 ppbv on average in cold months. The vehicular contribution to ambient isoprene was largely masked over by the noontime surge of isoprene in hot seasons, but was still able to be vaguely observed on the slopes of the isoprene peaks mimicking the rush-hour features of ethylene. In winter, the diurnal variations of isoprene were very similar to those of ethylene, which suggests that ambient isoprene in cold months was almost of traffic origin.This study based on the continuous dataset could enhance the key findings in previous flask studies in the same metropolis. While canister sampling had a major advantage of area coverage, the highly time-resolved fixed-site monitoring could better reveal the evolution process from a biogenically overwhelmed condition in hot months to the condition where the biogenic source weakened to reveal the traffic source in cold months.

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“…VOCs of anthropogenic origin, including aromatics and C 4 -C 6 alkanes, have higher mixing ratios in winter. This difference can be explained by three factors (Boudries et al, 1994;Cheng et al, 1997;Na and Kim, 2001;Swanson et al, 2003;Yang et al, 2005;Shirai et al, 2007): (i) a stronger temperature inversion in winter than in summer, leading to a mean daytime boundary layer 3 times shallower in winter than in summer at SIRTA (440 ± 220 m and 1340 ± 610 m, respectively, between 9 a.m. and 6 p.m.) (Filella and Peñuelas, 2006); (ii) lower OH radical concentrations in winter and thus less depletion by photochemistry (Michoud et al, 2012(Michoud et al, , 2014; and finally (iii) sources of different nature, composition and/or strengths. Different primary anthropogenic sources are known to be subject to the seasonal variations detailed in the last assumption, among these is the fuel evaporation.…”

Section: Seasonal Variations Of Vocsmentioning

confidence: 99%

Volatile and intermediate-volatility organic compounds in sub-urban Paris: variability, origin and importance for SOA formation

Ait-Helal¹,

Borbon²,

Sauvage³

et al. 2014

Preprint

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Abstract. Measurements of gaseous and particulate organic carbon were performed during the MEGAPOLI experiments, in July 2009 and January–February 2010, at the SIRTA observatory in sub-urban Paris. Measurements of primary and secondary volatile organic compounds (VOCs), of both anthropogenic and biogenic origins, including for the first time C12-C16 n-alkanes of intermediate volatility (IVOCs), suspected to be efficient precursors of secondary organic aerosol (SOA). The time series of gaseous carbon are generally consistent with times series of particulate organic carbon at regional scales and are clearly affected by meteorology and air mass origin. Concentration levels of anthropogenic VOCs in urban and sub-urban Paris were surprisingly low (2–963 ppt) compared to other megacities worldwide and to rural continental sites. Urban enhancement ratios of anthropogenic VOC pairs agree well between the urban and sub-urban Paris sites, showing the regional extent of anthropogenic sources of similar composition. Contrary to other primary anthropogenic VOCs (aromatics and alkanes), IVOCs showed lower concentrations in winter (< 5 ppt) compared to summer (13–27 ppt) in agreement with a gas-particle partitioning in favor of their transfer to the particle phase in winter. Higher concentrations of most oxygenated VOCs in winter (18–5984 ppt) suggest their dominant primary anthropogenic origin. The respective role of primary anthropogenic gaseous compounds in regional SOA formation was investigated by estimating the SOA mass concentration expected from the anthropogenic VOCs and IVOCs (I / VOCs) measured at SIRTA. From an approach based on emissions inferred from the I / VOC concentrations times the SOA formation yields', the so-called integrated approach conducted in this study, 46% of the SOA measured at SIRTA is explained by our measured concentrations of I / VOC, with 10% explained by only C12-C16 IVOCs. From results of an alternative time-resolved approach, the explained variability of the SOA concentrations is improved when the IVOCs are taken into account. Both approaches, which are based on ambient measurements of particular I / VOCs, emphasize the importance of the intermediate volatility compounds in the SOA formation, and support previous results from chamber experiments and modeling studies. The approaches results support the need to make systematic the IVOCs speciated measurement during field campaigns.

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Diurnal and seasonal cycles of ozone precursors observed from continuous measurement at an urban site in Taiwan

Cited by 30 publications

References 26 publications

Trends of Ambient Concentrations of Gaseous Air Pollutants in Almadinah Al Menawwarah, Central Area, Saudi Arabia

Trends of Ambient Concentrations of Gaseous Air Pollutants in Almadinah Al Menawwarah, Central Area, Saudi Arabia

Revelation of Coupling Biogenic with Anthropogenic Isoprene by Highly Time-Resolved Observations

Volatile and intermediate-volatility organic compounds in sub-urban Paris: variability, origin and importance for SOA formation

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