Abstract
Abstract. Intensive measurements of submicron aerosol particles and their chemical composition were performed with an Aerosol Chemical Speciation Monitor (ACSM) at the Cabauw Experimental Site for Atmospheric Research (CESAR) in Cabauw, the Netherlands, sampling at 5 m height above ground. The campaign lasted nearly 1 year from July 2012 to June 2013 as part of the EU-FP7-ACTRIS project (Q-ACSM Network). Including equivalent black carbon an average particulate mass concentration of 9.50 µg m−3 was obtained during the whole campaign with dominant contributions from ammonium nitrate (45 %), organic aerosol (OA, 29 %), and ammonium sulfate (19 %). There were 12 exceedances of the World Health Organization (WHO) PM2.5 daily mean limit (25 µg m−3) observed at this rural site using PM1 instrumentation only. Ammonium nitrate and OA represented the largest contributors to total particulate matter during periods of exceedance. Source apportionment of OA was performed season-wise by positive matrix factorization (PMF) using the multilinear engine 2 (ME-2) controlled via the source finder (SoFi). Primary organic aerosols were attributed mainly to traffic (8–16 % contribution to total OA, averaged season-wise) and biomass burning (0–23 %). Secondary organic aerosols (SOAs, 61–84 %) dominated the organic fraction during the whole campaign, particularly on days with high mass loadings. A SOA factor which is attributed to humic-like substances (HULIS) was identified as a highly oxidized background aerosol in Cabauw. This shows the importance of atmospheric aging processes for aerosol concentration at this rural site. Due to the large secondary fraction, the reduction of particulate mass at this rural site is challenging on a local scale.
Highlights
Atmospheric aerosols have large impacts on the climate directly by scattering and absorbing shortwave radiation
For more than 8000 simultaneous observations, the results showed that aerosol measurements through this 60 m sampling line underestimate PM10 equivalent black carbon (eBC) by approximately 33 % with an uncertainty of 7 %
This can be explained by the low concentrations of Mg, Na, K, and Ca as measured by the MARGA and the assumption that the majority of dust particles is most likely found in particles with diameters larger than 1 or even 2.5 μm (Finlayson-Pitts and Pitts, 2000, and references therein)
Summary
Atmospheric aerosols have large impacts on the climate directly by scattering and absorbing shortwave radiation. Particles can adversely impact human health by, e.g., increasing the probability of cardiopulmonary and lung cancer mortality (Pope et al, 2002). The World Health Organization (WHO) recently estimated that, globally, 3.7 million deaths were attributable to ambient air pollution in both cities and rural areas in 2012 (EU, 2008). This mortality is reported to be due to exposure to small particulate matter (PM10), which can cause cardiovascular and respiratory disease and cancers. Particles with smaller diameters such as PM2.5 or PM1 are reported to have enhanced toxicological effects since they can deposit more deeply in the respiratory system and remain suspended for longer periods of time (Pope and Dockery, 2006).
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