Evaluation of ACSM response to different mixtures of organic and inorganic solutions, and assessing the impact on organic source apportionment results

Real time and long-term monitoring of aerosol chemical species is the subject of great scientific concerns and numerous technological developments. The Aerodyne Aerosol Chemical Speciation monitor (ACSM) has been developed for this purpose. It is currently operational at over 60 monitoring stations worldwide, with almost half of them being located in Europe (notably within the Aerosols, Clouds, and Trace gases Research InfraStructure). Understanding the reponse of these instruments to different chemical species and quantifying any possible artefacts is essential if we are to use these measurements for comparative studies and for model evaluation and development. A few recent studies have illustrated such possible measurement artefacts, notably at the mz44 peak (Crenn et al, 2015, Frohlich et al, 2015). The related variability in instrument response has been linked to an artefact response to inorganic aerosol (Pieber et al.,2016), however more recent work has illustrated that this response is dependent on aerosol mixing state (Freney et al., 2019). Here, we present results of laboratory experiments where the mz44 artefact was evaluated for various inorganic and organic mixtures, and a co-located measurement campaign in ambient air..

Assessment of air quality microsensors versus reference methods: The EuNetAir Joint Exercise - Part II

The EuNetAir Joint Exercise focused on the evaluation and assessment of environmental gaseous, particulate matter (PM) and meteorological microsensors versus standard air quality reference methods through an experimental urban air quality monitoring campaign. This work presents the second part of the results, including evaluation of parameter dependencies, measurement uncertainty of sensors and the use of machine learning approaches to improve the abilities and limitations of sensors. The results confirm that the microsensor platforms, supported by post processing and data modelling tools, have considerable potential in new strategies for air quality control. In terms of pollutants, improved correlations were obtained between sensors and reference methods through calibration with machine learning techniques for CO (r2=0.13-0.83), NO2 (r2=0.24-0.93), O3 (r2=0.22-0.84), PM10 (r2=0.54-0.83), PM2.5 (r2=0.33-0.40) and SO2 (r2=0.49-0.84). Additionally, the analysis performed suggests the possibility of compliance with the data quality objectives (DQO) defined by the European Air Quality Directive (2008/50/EC) for indicative measurements

Results of the first-ever ACSM intercomparison study from the ACTRIS-ACSM network

International audienceAs part of the EU-FP7 ACTRIS program, a large international intercomparison study of 15 aerosol mass spectrometers (13 Q-ACSM, 1 ToF-ACSM and 1 HR-ToF-AMS) has been performed from 15 Nov. to 2 Dec. 2013 at the LSCE in-situ atmospheric platform which is part of the French SIRTA observatory (http://sirta.ipsl.fr) located at 20km southwest of Paris. During this period, each instrument measured the major non-refractory submicron aerosols (NR-PM1) components (organic matter, nitrate, sulfate, and ammonium) in ambient air. The accuracy of Q-ACSM instruments was determined by comparison with various co-located instruments (TEOM-FDMS, SMPS, OPC, OC-EC Sunset Field analyzer, PILS-IC, aethalometers, nephelometers, and filter sampling). The measurement precision was also evaluated by intercomparing the correlation of absolute mass concentrations for all the NR-PM1 species. The ACSM analytical uncertainties were then estimated by applying a statistical approach in order to evaluate the analytical standard deviations between ACSMs and to highlight any bias or influencing factor on the ACSM measurements. For this purpose, the Z-score indicator representing performance criteria was used making it possible to measure its relative deviation to the assigned value. Fig. 1 summarizes the Z-Score results applied to the 13 Q-ACSM datasets for the major chemical species of the NR-PM1. All the ACSMs present satisfactory Z-Score values (a Z-Score value of 3 is considered as the limit value) whatever the considered parameter highlighting the instrument precision