Chemical composition and source identification of PM10 in five North Western European cities

Particulate matter (PM) is a complex, heterogeneous mixture that changes in time and space. It has many different chemical constituents, several of which have been identified as potential contributors to toxicity, and varying physical characteristics. Identifying and quantifying the effects of specific components or source-related combinations on human health, particularly when particles interact with other co-pollutants, therefore represents one of the most challenging areas of environmental health research. Owing to the importance of PM10 chemical composition in understanding particulate pollution sources, 1942 PM10 samples were simultaneously collected at five sites (four urban background sites located in Amsterdam (AD), Antwerp (AP), Leicester (LE) and Lille (LL), and one industrial site at Wijk aan Zee (WZ)) across North-West Europe from April 2013 to May 2014, and chemical species and sources of PM10 were investigated. PM10 samples were chemically analysed for water-soluble ions (NO3−, SO42−, Cl−, NH4+, Na+, K+, Mg2+, and Ca2+), carbonaceous species (OC, and EC), minerals (Al, Ca, Fe, Ti, and K), trace elements (As, Ba, Cd, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, and Zn), and monosaccharides (levoglucosan, galactosan, and mannosan). Spatial and seasonal variations of the atmospheric concentrations of species were also investigated. In order to reconstruct the particle mass, the determined constituents were classified into seven classes as follows: mineral dust (MD), organic matter (OM), elemental carbon (EC), trace elements (TE), sea salt (SS), secondary inorganic aerosol (SIA), and monosaccharides (MSS). Strong correlations (R2 = 0.88–0.96) were found between chemically determined and gravimetrically measured PM10 masses for all sites. According to chemical mass closure, the major components of PM10 were SIA, followed by OM and MD at the four urban sites, and the major components of PM10 were SIA, followed by MD and SS at an industrially influenced site. SIA dominated the PM10 profiles at all sites, accounting for 36, 35, 32, 36, and 32% at AD, AP, LE, LL, and WZ, respectively. Five PCA factors explained 67, 80, 76, and 74% of the variance of the data at AD, AP, LL and WZ respectively. In addition, four factors are extracted for LE site explaining 71% of the variance. The PCA results showed that secondary aerosols, biomass burning, and traffic emissions were the most important sources across North-West Europe.