Sources of the PM10 aerosol in Flanders, Belgium, and re-evaluation of the contribution from wood burning Willy Maenhaut1,2, Reinhilde Vermeylen2, Magda Claeys2, Jordy Vercauteren3 and Edward Roekens3 1Dept. Analytical Chemistry, Ghent University, Belgium 2Dept. Pharmaceutical Sciences, University of Antwerp, Belgium 3Flemish Environment Agency (VMM), Antwerpen, Belgium EAC 2016, Tours, France

Introduction In 2010-2011 we conducted a 1-year study at 7 sites in Flanders (Belgium) to assess the contribution from wood burning (WB) to the PM10 mass and the PM10 organic carbon (OC) using levoglucosan (levo) as WB tracer and conversion factors of Schmidl et al., AE [2008], see Maenhaut et al., STE [2012] WB PM10 mass = levo * 10.7 WB PM10 OC = levo * 5.59 In 2011-2012 similar 1-year study at 4 urban background sites in Flanders, i.e., Antwerpen, Gent, Brugge, and Oostende same species measured as in the 2010-2011 study, but in addition: water-soluble inorganic species and elements to assess WB: same approach used as in the 2010-2011 study, but in addition: positive matrix factorization (PMF), EPA PMF 5 EAC 2016, Tours, France

Location of the 4 sampling sites Brussels EAC 2016, Tours, France

Sampling and analyses From 30 June 2011 to 1 July 2012 PM10 aerosol samples simultaneously taken every 4th day at 4 sites in Flanders, Belgium on 47-mm diam. Pallflex quartz fibre filters PM10 mass determined by weighing of the filters at 20 °C and 50% relative humidity [done by VMM] Organic, elemental, and total carbon [OC, EC, and TC (= OC + EC)] measured with thermal-optical instrument from Sunset Lab using NIOSH temperature protocol, transmittance (TOT) Levoglucosan, mannosan and galactosan determined by gas chromatography / mass spectrometry (GC/MS) 8 water-soluble ions measured by ion chromatography (IC) 15 elements determined by a combination of inductively coupled plasma atomic emission spectrometry and mass spectrometry EAC 2016, Tours, France

PMF: Selected base results as a function of the number of factors 10-factor base solution retained contributions from WB to PM10 mass and OC quite robust EAC 2016, Tours, France

PMF: 10-factor base solution, factor names and key species in each factor key species are defined as those species with typically at least one third of their mass, on average, attributed to the factor EAC 2016, Tours, France

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PMF: wood burning (WB) The average contributions of wood smoke for the four sites were quite substantial in winter for the PM10 mass: from 12.5 to 20% for the PM10 OC: from 47 to 64% Wood burning appeared to be also a notable source of As, Cd, and Pb these three elements had similar or higher annual median percentage apportionments to WB as K+, which is typically used as an indicator element for wood smoke for Gent and Brugge: between 10 and 20% from WB EAC 2016, Tours, France

Wood burning: levo approach vs. PMF the data derived from levoglucosan compared very well with those obtained in our previous study using the same approach however, the PMF data are substantially larger than those derived from levoglucosan EAC 2016, Tours, France

Scatter plots of PMF-derived WB PM (brown squares) and OC (red diamonds) vs. levo and regression lines, forced through the origin EAC 2016, Tours, France

Conclusion The levoglucosan conversion factors of Schmidl et al. [2008] do not seem to be applicable for WB in Flanders the uncertainty associated with the use of the Schmidl et al. [2008] conversion factors for Flanders was estimated to be of the order of 30% in our 2010-2011 study [Maenhaut et al., 2012] From scatter plots of the PMF-derived wood smoke PM10 OC and PM versus levoglucosan, we arrive at conversion factors of 9.7 and 22.6, respectively it is recommended to use these latter factors for deriving the contribution from wood smoke when making use of levoglucosan as single marker in future studies in Flanders it is estimated that the percentage uncertainty, which is associated with these conversion factors, is smaller than 20% EAC 2016, Tours, France

Further conclusions The impact from wood burning on the PM10 mass and OC levels in Flanders is substantially larger than previously thought The contribution of the heavy oil burning component showed a clear tendency to decrease with distance from the coast this was likely caused by the larger impact from ship emissions at the sites closer to the coast The non-ferrous metals factor, which was characterized by As, Cd and Pb, exhibited by far its highest level at Antwerpen there is a major non-ferrous metals plant in Hoboken, which is located within greater Antwerpen, and this plant is still a large source of airborne As, Cd, and Pb [VMM, 2014] Wood burning was also a notable source of As, Cd, and Pb these three elements had similar or higher annual median percentage apportionments to wood burning as K+, which is typically used as an indicator element for wood smoke EAC 2016, Tours, France

Thank you for your attention This work was published: Maenhaut et al., Sci. Total Environ. 562 (2016) 550-560 Thank you for your attention EAC 2016, Tours, France

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