Source apportionment of PM10 based on offline chemical speciation data at 24 European sites

Abstract

This study applied Positive Matrix Factorization (PMF) to PM10 speciation datasets from 24 urban sites across six European countries (France, Greece, Italy, Portugal, Spain, and Switzerland) to perform a detailed source apportionment (SA) analysis. By using a consistent source apportionment tool for all datasets, the study enhances the comparability of PM10 SA results across urban Europe. The results identified seven major PM10 sources including road traffic, biomass burning, crustal/mineral sources, secondary aerosols, industrial emissions, sea salt, and heavy oil combustion (HOC). Road traffic emerged as the predominant source of PM10 in urban areas, with contributions varying by location, but representing as much as 41%in high-traffic zones. Biomass burning was detected at 23 sites, contributing 8% to 41%on yearly averages, with substantial increase in winter. Crustal sources were present at all sites (3–33%). Industrial sources contributed relatively less PM10 mass, which was identified at 10 sites with contributions ranging from 2%to 14%. Secondary inorganic and organic aerosol, consisting primarily of ammoniumnitrates and sulfates, and organicmatter, formed a portion of the PM10mass (5–41%). These secondary factors are primarily influenced by anthropogenic emissions, including the various combustionprocesses.Sea salt,predominantly foundincoastal areas,contributed between 4%and 21%, reflecting the impact of themarine environments on air quality. This source was very often ‘aged’ (mixed with anthropogenic pollutants from different origins). Additionally, HOC, especiallyemits fromshipping activities, and traced by V andNi, was also a frequent contributing source (2–15%for 9 sites), indicating a need formore stringent emission controls. The chemical comparison is performed which indicates road traffic and secondary aerosols, showed consistent chemical profiles across sites, while industrial, HOC, and crustal sources displayed significant site-specific variability. These findings underscore the need for tailored air quality strategies according to local sources of emissions and the importance of long-term PM speciation monitoring for effective pollution control.