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Selected VOC fluxes as a function of CO2 fluxes from Helsinki, London and Mexico City (note the logarithmic scale). The average CO2 and VOC fluxes of Helsinki are taken from Järvi et al. (2012) (scaled from the annual average) and this study, respectively. The corresponding average values of London are from Helfter et al. (2011) (scaled from the annual average) and Langford et al. (2010). All values of Mexico City are from MILAGRO/MCMA-2006 campaign (Velasco et al., 2009). Pie diagrams show the corresponding fractions of each compound.
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We measured volatile organic compounds (VOC), carbon dioxide (CO2) and carbon monoxide (CO) at an urban background site near the city centre of Helsinki, Finland, Northern Europe. The VOC and CO2 measurements were obtained between January 2013 and September 2014 whereas for CO a shorter measurement campaign in April–May 2014 was conducted. Both ant...
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... In order to evaluate the pollution levels of VOCs in this study, their mean mixing ratios were compared with those observed at other urban sites, measured by PTR-MS and reported in ppbv worldwide, as shown in Fig. 4. The OVOCs measured in this study were in the range of those found within some Asia cities but were significantly higher than those observed in European. Acetaldehyde measured in Changzhou (4.96 ppbv) was comparable with that in Lanzhou (5.05 ppbv) (Zhou et al., 2019), Ahmedabad (5.60 ppbv) (Sahu and Saxena, 2015), and Belgrade (5.04 ppbv) (Stojić et al., 2015), while the concentration was much higher than that in London (0.16 ppbv) (Valach et al., 2015), Paris (0.54 ppbv) (Baudic et al., 2016), Helsinki (0.59 ppbv) (Rantala et al., 2016), and Innsbruck (0.21 ppbv) (Karl et al., 2020). As for acetone + propanal, the concentration observed in this study (4.15 ppbv) was closed to the summer Beijing (4.16 ppbv) , Pune (4.85 ppbv) (Maji et al., 2020), and higher than that in London (0.31 ppbv) (Valach et al., 2015) and Paris (0.73 ppbv) (Baudic et al., 2016). ...
... Besides, isoprene in Changzhou (0.20 ppbv) was comparable with that measured in Shenzhen (0.29 ppbv) , lower than that measured in Athens (1.05 ppbv) (Kaltsonoudis et al., 2016) and Istanbul (0.68 ppbv) (Thera et al., 2019), while higher than that measured in Tokyo (0.06 ppbv) (Yoshino et al., 2012). Acetonitrile (0.51 ppbv) was closed to levels in Lanzhou (0.69 ppbv) (Zhou et al., 2019), lower than that in Belgrade (3.38 ppbv) (Stojić et al., 2015) and winter Beijing (1.34 ppbv) (Sheng et al., 2018), while higher than levels in Helsinki (0.10 ppbv) (Rantala et al., 2016) and Istanbul (0.18 ppbv) (Thera et al., 2019).The discrepancies in acetonitrile and isoprene levels at different urban sites might be related to the biomass burning activities, surrounding vegetation coverage, temperature and seasons. ...
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