Quantifying primary and secondary source contributions to ultrafine particles in the UK urban background

Abstract

• Particle total number concentration (TNC) does not always reflect variations in traffic 14 emissions 15• Primary and secondary sources contribute in a seasonally variant and quantifiable way 16 to particle number concentrations in Leicester. 17• New particle formation was a significant contributor around midday to TNC in the 18Leicester urban atmosphere. 19• (2014 and 2015). A derived chemical climatology 36for the pollutants showed maximum concentrations for all pollutants during the cold period 37 except O3 which peaked during spring. Quantification of primary and secondary sources of 38 ultrafine particles (UFPs) was undertaken using eBC as a tracer for the primary particle number 39 concentration in the Leicester urban area. At the urban background site, which is influenced by 40 fresh vehicle exhaust emissions, TNC was segregated into two components, TNC = N1 + N2. 41The component N1 represents components directly emitted as particles and compounds which 42 nucleate immediately after emission. The component N2 represents the particles formed during 43 the dilution and cooling of vehicle exhaust emissions and by in situ new particle formation 44 (NPF). The values of highest N1 (49%) were recorded during the morning rush hours (07:00-45 09:00 h), correlating with NOx, while the maximum contribution of N2 to TNC was found at 46 midday (11:00-14:00 h), at around 62%, correlated with O3. Generally, the percentage of N2 47 (57%) was greater than the percentage of N1 (43%) for all days at the AURN site over the 48 period of the study. For the first time the impact of wind speed and direction on N1 and N2 49 was explored. The overall data analysis shows that there are two major sources contributing to 50 TNC in Leicester: primary sources (traffic emissions) and secondary sources, with the majority 51 of particles of secondary origin.

Seasonal and geographical variability of nitryl chloride and its precursors in Northern Europe

“…Measurements of ClNO 2 , O 3 , NO 2 and aerosol composition were taken during seven periods between 2014 and 2016 at three locations in the United Kingdom: Leicester (52°38′N, 01°08′W) is a middle‐sized city (pop: ∼330,000) in central England, ∼200 km from the ocean. The measurements were made at two sites on the University campus: the Department of Chemistry and the local AURN station (Automatic Urban and Rural Network, http://uk-air.defra.gov.uk/networks/site-info?uka_id=UKA00573), which is classified as an urban background site (Hama et al, ). The two sites are ∼400 m apart and, for this work, were analysed together. Penlee Point (50°19′N, 04°11′W) is on the southwestern coast of the United Kingdom, ∼6 km southwest of the city of Plymouth (pop: ∼250,000).…”

“…The 1-min detection limit for ClNO 2 was 4.2 ppt at 2σ (5.1 ppt at 3σ), with 18% accuracy and 14% precision. O 3 was measured by UV absorption in Leicester (Model T400, Teledyne Technologies Inc., City of Industry, CA, Hama et al, 2017), in Penlee Point (Model 205, 2B Technologies, Boulder, CO, Yang et al, 2016) and in Weybourne (Model 49i, Thermo Fisher Scientific Inc., Franklin, MA). NO 2 was measured at Leicester and in Penlee Point with a Teledyne Model T200 NO/NO 2 /NO x analyser, using chemiluminescence detection with a molybdenum converter (Hama et al, 2017).…”

“…The measurements were made at two sites on the University campus: the Department of Chemistry and the local AURN station (Automatic Urban and Rural Network, http://uk-air.defra.gov.uk/networks/site-info? uka_id=UKA00573), which is classified as an urban background site(Hama et al, 2017).…”

Impact of cold temperature on Euro 6 passenger car emissions

“…Winter season is associated with high pollution episodes ( Custódio et al., 2016 , Wang et al., 2017 ). Recent seasonal studies have shown that in some urban areas the highest levels of NOx, NH 3 , CO and PM occur in the cold season ( Hofman et al., 2016 , Hama et al., 2017 ). Those studies, as well as the recent report presented by the European Environment Agency ( EEA, 2014 ), indicate that transport sector is one of the main sources of these air pollutants.…”

Measurement report: Long-term real-time characterisation of the submicronic aerosol and its atmospheric dynamic in a Mediterranean coastal city: Tracking the polluted events at the Marseille-Longchamp supersite

“…investigated using the methodology developed by Rodríguez and Cuevas (2007). This methodology has been extensively applied in urban environment to apportion the number concentration of primary and secondary sources (del Águila et al, 2018;González et al, 2011;Hama et al, 2017a;Hama et al, 2017b;Reche et al, 2011;Rodríguez and Cuevas, 2007;Tobías et al, 2018). To refine the method, BCFF was used instead of total BC to better apportion primary traffic emissions.…”