Summer ammonia measurements in a densely populated Mediterranean city

Abstract

Real-time measurements of ambient concentrations of gas-phase ammonia (NH<sub>3</sub>) were performed in Barcelona (NE Spain) in summer between May and September 2011. Two measurement sites were selected: one in an urban background traffic-influenced area (UB) and the other in the historical city centre (CC). Levels of NH<sub>3</sub> were higher at CC (5.6 ± 2.1 μg m<sup>−3</sup> or 7.5 ± 2.8 ppbv) compared with UB (2.2 ± 1.0 μg m<sup>−3</sup> or 2.9 ± 1.3 ppbv). This difference is attributed to the contribution from non-traffic sources such as waste containers, sewage systems, humans and open markets more dense in the densely populated historical city centre. Under high temperatures in summer these sources had the potential to increase the ambient levels of NH<sub>3</sub> well above the urban-background-traffic-influenced UB measurement station. Measurements were used to assess major local emissions, sinks and diurnal evolution of NH<sub>3</sub>. The measured levels of NH<sub>3</sub>, especially high in the old city, may contribute to the high mean annual concentrations of secondary sulfate and nitrate measured in Barcelona compared with other cities in Spain affected by high traffic intensity. Ancillary measurements, including PM<sub>10</sub>, PM<sub>2.5</sub>, PM<sub>1</sub> levels (Particulate Matter with aerodynamic diameter smaller than 10 μm, 2.5 μm, and 1 μm), gases and black carbon concentrations and meteorological data, were performed during the measurement campaign. The analysis of specific periods (3 special cases) during the campaign revealed that road traffic was a significant source of NH<sub>3</sub>. However, its effect was more evident at UB compared with CC where it was masked given the high levels of NH<sub>3</sub> from non-traffic sources measured in the old city. The relationship between SO<sub>4</sub><sup>2−</sup> daily concentrations and gas-fraction ammonia (NH<sub>3</sub>/(NH<sub>3</sub> + NH<sub>4</sub><sup>+</sup>)) revealed that the gas-to-particle phase partitioning (volatilization or ammonium salts formation) also played an important role in the evolution of NH<sub>3</sub> concentration in summer in Barcelona

Chemical characteristics of size-resolved atmospheric aerosols in Iasi, north-eastern Romania: nitrogen-containing inorganic compounds control aerosol chemistry in the area

“…3.2.2, at the investigated site a reduction in both in NO − 3 and SO 2− 4 was observed over the warm season and this may cause a further increase in gasphase NH 3 . It is also interesting to observe that the reaction rate constant of (NH 4 ) 2 SO 4 aerosol formation is similar to the rate constant of NH 4 NO 3 formation (Harrison and Kitto, 1992;Pandolfi et al, 2012;Behera et al, 2013), and both are much higher than the rate constant between NH 3 and HCl (Behera and Sharma, 2012). This issue probably dictates the competition of any of the particulate SO 2− 4 , NO − 3 , and Cl − for the available NH + 4 .…”

Variation of Urban Atmospheric Ammonia Pollution and its Relation with PM2.5 Chemical Property in Winter of Beijing, China

“…The gas-to-particle conversion processes in ambient atmosphere may produce inorganic ammonium salts of ammonium bisulfate (NH 4 HSO 4 ), ammonium sulfate ((NH 4 ) 2 SO 4 ), (Tsai et al, 2014). It is known that NH 4 HSO 4 or (NH 4 ) 2 SO 4 is preferentially formed among the ammoniumassociated compounds because the affinity of sulfuric acid for NH 3 is much larger than that of nitric acid and hydrochloric acid for NH 3 (Pandolfi et al, 2012;Behera et al, 2013b ) (Behera and Sharma, 2012). The overall relationship between molar concentrations of NH 3 and the corresponding PM 2.5 -bound NH 4 + during the whole field measurement period was shown in Fig.…”

“…Norman et al (2009) and Meng et al (2011) compared different ammonia analysis methods and found accuracy of the online method is acceptable (correlation coefficient ranged from 0.77-0.94). Moreover, the chemiluminescence method has been used in several studies to measure ambient NH 3 and has exhibited satisfactory performances (Behera et al, 2010;Meng et al, 2011;Pandolfi et al, 2012). To obtain a finer temporal view of NH 3 variation, the NH 3 data from the ammonia analyzer was used in this study.…”

“…In some cities around the world, measurements of ambient NH 3 have been reported, for example, in Rome (Perrino et al, 2002), New York City (Li et al, 2006), Manchester (Whitehead et al, 2007), Barcelona (Pandolfi et al, 2012) and Seoul (Phan et al, 2013). In China, continuous measurements of NH 3 spanned over a year have been reported in Beijing (Meng et al, 2011) and Xi'an (Cao et al, 2009), which focused on characterizing the levels and variations of NH 3 .…”

Chemical characteristics of size resolved atmospheric aerosols in Iasi, north-eastern Romania. Nitrogen-containing inorganic compounds controlling aerosols chemistry in the area

“…Moreover, at the investigated site, during the cold seasons temperature and relative humidity were of 5.3 ± 3.9 °C and, respectively, (65.3 ± 12.8) % and, according with details presented in Table 4, the (NO 3 -, NH 4 + (total)) pair presented significant correlation (with Pearson coefficient of 0.98, p < 0.001, at the 99.9 % confidence level) only during the cold seasons (low temperature and high relative humidity being favourable for particulate NH 4 NO 3 formation, Stelson and Seinfeld, (1982)). During the warm 25 seasons (temperature and relative humidity of 18.9 ± 3.8 °C and, respectively, 40.5 ± 7.7 %) the (NO 3 -, NH 4 + (total)) pair correlation is of very poor significance most probably due to the influence of meteorological conditions which were not favourable for particulate NH 4 NO 3 formation (increasing temperature and decreasing relative humidity limit the production of NH 4 NO 3 aerosol (Matsumoto and Tanaka 1996;Utsunomiya and Wakamatsu 1996;Alastuey et al 2004) (by an irreversible reaction due to H 2 SO 4 affinity for NH 3 ), known to be as high as 1.5 × 10 -4 sec -1 (Harrison and Kitto, 1992), is almost similar with the reaction rate constants for NH 4 NO 3 formation (by a balanced reaction due to NH 3 affinity for HNO 3 ), which is of the order of 1.59 × 10 -4 m 3 µmoL -1 s -1 (Pandolfi et al, 2012;Behera et al, 2013 and NH 4 NO 3 will be formed via reactions R1 (Cziczo et al, 1997;Zhang et al, 2015) and R2 (Fountoukis and Nenes, 2007;Zhang et al, 2015), (Utsunomiya and Wakamatsu, 1996) and, moreover, NH 4 NO 3 will form only when available excess NH 3 will react with HNO 3 . Backes et al (2016), from their modelling study, suggest that a reduction of NH 3 emissions by 50 % may lead to a 24 % reduction of the total PM 2.5 concentrations in northwest Europe, with the reduction mainly driven by reduced formation of NH 4 NO 3 .…”