Effect of dispersion normalisation on PM10 elemental sources at a rural background site in Central Europe

Rural background sites, representative of a wider area, are important for investigating the influence of regional and long-range transport as well as long-term trends in PM concentrations (Putaud et al., 2010). Dispersion normalisation using the ventilation coefficient has recently been shown to be an effective approach that provides improved source apportionment results with clearer diel and seasonal patterns for speciated PM datasets (Dai et al., 2020). The focus of this study was to assess the influence of dispersion conditions represented by ventilation coefficient on speciated PM₁₀ concentrations and their origins at the National Atmospheric Observatory Košetice (NAOK, 49°35'N, 15°05'E), a rural background site in Central Europe (LRI ACTRIS ERIC, https://www.actris.eu/).

PM₁₀ elemental composition was measured every 4-h for three years (2021 – 2023) by the Xact625i (Cooper Environmental Services, USA), an online ED-XRF ambient multi-metals monitor. Ventilation coefficient was calculated with 1-h resolution by the numerical weather prediction model ALADIN for subsequent dispersion normalisation of highly time-resolved and speciated PM₁₀ data. Advanced receptor modelling (US EPA PMF 5.0) was applied to both non-dispersion and dispersion normalised highly time-resolved PM₁₀ elemental datasets.

PMF resolved five factors of PM₁₀ (secondary sulphate, residential heating – biomass and coal, soil/re-suspended dust, sea/road salt, industry) for both datasets with almost identical chemical profiles. The factor contributions were positively (lower contributions – secondary sulphate, residential heating, and salt) and negatively (higher contributions – soil/re-suspended dust and industry) influenced by dispersion conditions. Dispersion normalisation provided improved source apportionment results with clearer diel and seasonal patterns, primarily for secondary sulphate and residential heating, the main sources of elemental PM₁₀.

This conference contribution was supported by the Ministry of Education, Youth and Sports of the Czech Republic under grant ACTRIS-CZ (LM2023030).

 

Putaud, J.P., et al., 2010. A European aerosol phenomenology — 3: physical and chemical characteristics of particulate matter from 60 rural, urban, and kerbside sites across Europe. Atmos. Environ. 44, 1308–1320.

Dai, Q. at al., 2020. Dispersion Normalized PMF Provides Insights into the Significant Changes in Source Contributions to PM2.5 after the COVID-19 Outbreak. Environ. Sci. Tech. 54, 16, 9917–9927.