Water soluble aerosols and gases at a UK background site – Part 1: Controls of PM<sub>2.5</sub> and PM<sub>10</sub> aerosol composition

Abstract

Abstract. There is limited availability of long-term, high temporal resolution, chemically speciated aerosol measurements which can provide further insight into the health and environmental impacts of particulate matter. The Monitor for AeRosols and Gases (MARGA, Applikon B.V., NL) allows for the characterisation of the inorganic components of PM 10 and PM 2.5 (NH provided the single largest contribution to PM 2.5 fraction in all seasons. Sea salt was the main component (73 %) of the PM coarse fraction (PM 10 -PM 2.5 ), though NO − 3 was also found to make a relatively large contribution to the measured mass (17 %) providing evidence of considerable processing of sea salt in the coarse mode. There was on occasions evidence of aerosol from combustion events being transported to the site in 2012 as high K + concentrations (deviating from the known ratio in sea salt) coincided with increases in black carbon at the site. Pollution events in PM 10 (defined as concentrations > 12 µg m −3 ) were on average dominated by NH + 4 and NO − 3 , where smaller loadings at the site tended to be dominated by sea salt. As with other western European sites, the charge balance of the inorganic components resolved were biased towards cations, suggesting the aerosol was basic or more likely that organic acids contributed to the charge balance. This study demonstrates the UK background atmospheric composition is primarily driven by meteorology with sea salt dominating air masses from the Atlantic Ocean and the Arctic, whereas secondary inorganic aerosols tended to dominate air masses from continental Europe.

Measurements of PM10 ions and trace gases with the online system MARGA at the research station Melpitz in Germany – A five-year study

“…These salts can reach Melpitz through long-range transport. Additionally, fine mode NO 3 − is formed during the oxidation of NO x emissions of anthropogenic origin, while the chloride-nitrate exchange leads to the formation of course mode NO 3 − particles, even over Central and Western Europe (Dasgupta et al 2007;Twigg et al 2015). This can explain the high emission probability shown in Fig.…”

“…This course in time is equally pronounced during every season. In the fine mode, NO 3 − is mainly bound in the form of NH 4 NO 3 , which is dependent on the gas phase precursor concentrations, temperature, humidity, and aerosol chemical composition (Poulain et al 2011;Twigg et al 2015). The volatile behaviour of NH 4 NO 3 results in the formation of the gaseous compounds HNO 3 and NH 3 for higher temperatures and low humidity.…”

“…Makkonen et al (2012) observed predominantly acidic particles in winter and basic aerosol in spring due to road dust emissions, resulting in high Ca 2+ concentrations, in Finland. Recently, Twigg et al (2015) , and (h) Ca 2+ and their seasonal dependence for spring (green), summer (red), autumn (black), and winter (blue). Each average was calculated for the whole measurement period from 2010 to 2014 measurement period of 18 years.…”

Vertical distribution of aerosol optical properties in the Po Valley during the 2012 summer campaigns

“…) and gases (NH 3 , HNO 3 , SO 2 , HONO, HCl) at hourly resolution (Twigg et al , 2015). In the sampling box, the air passes through a Wet Rotating Denuder (WRD) (Keuken et 25 al., 1988) where water soluble gases are stripped from the air stream and collected in water.…”

“…The sampled air then continues through a Steam-Jet Aerosol Collector (SJAC, Khlystov et al, 1995;Slanina et al, 2001) where the water soluble aerosols are separated from the air stream and collected. The gas and aerosol samples are then analysed by online ion chromatography with high accuracies (detection limits as low as 0.01 µg m −3 (Twigg et al , 2015)). Size-selective particle cyclones are used in front of the two MARGA sampling boxes so that the size of the particles for analysis can be limited to an aerodynamic diameter of 30 less than 10 (PM10) or 1 (PM1) µm.…”