Composition and sources of particulate matter in an industrialised Alpine valley

Abstract

A three-week long field campaign was carried out under autumnal meteorological conditions at four valley floor sites in the industrialised Swiss Rhone Valley. For one week of stable meteorological conditions, particulate matter with an aerodynamic diameter below 10 μm (PM<sub>10</sub>) was analysed from daily filters using ion chromatography, X-ray fluorescence, anhydrosugars and radiocarbon analysis of the organic and elemental matter (OM and EM, respectively). Furthermore, PM<sub>1</sub> composition along the whole campaign was monitored in Massongex (a site near industries) by a seven-wavelength aethalometer and a quadrupole aerosol mass spectrometer (Q-AMS). At all sites, PM<sub>10</sub> secondary inorganics and non-fossil EM and OM exhibited relatively stable concentrations over the selected days. On the contrary, PM<sub>10</sub> fossil carbonaceous fractions, mineral dust components and several trace elements showed a significant decrease on Sunday, compared to the analysed working days. Their concentrations were also highly correlated. This evidenced the role of exhaust and resuspension emissions by heavy-duty vehicle traffic to the PM<sub>10</sub> concentrations along the valley. <br><br> In Massongex, organic matter and black carbon (BC) were the main contributors to PM<sub>1</sub> over the campaign (accounting for 45% and 18% of PM<sub>1</sub>, respectively). An optical discrimination of BC highlighted the prevalence of fossil over wood-burning sources. Three types of PM<sub>1</sub> organics could be identified by factor analysis: primary wood-burning organic aerosol (P-WBOA) dominated the PM<sub>1</sub> carbonaceous fraction, followed by oxygenated organics (OOA) mostly representing secondary organics, and by traffic or possibly industry-related hydrocarbon-like organics (HOA) as the smallest carbonaceous contribution. <br><br> Furthermore, unusually high contributions of fine chloride were detected at all sites. They were attributed to ammonium chloride (NH<sub>4</sub>Cl) in Massongex and represented the only significant component exclusively attributable to industrial emissions

On the isolation of OC and EC and the optimal strategy of radiocarbon-based source apportionment of carbonaceous aerosols

“…Consequently, thermal separation of OC and EC may suffer from untimely EC removal (Andreae and Gelencsér, 2006), described as the negative EC artefact. These losses are particularly enhanced for wood-burning-impacted samples because of the presence of inorganic combustion catalysts (Novakov and Corrigan, 1995) and of the lower refractivity of the wood-burning EC compared to fossil EC (Elmquist et al, 2006).…”

Radiocarbon analysis of elemental and organic carbon in Switzerland during winter-smog episodes from 2008 to 2012 – Part 1: Source apportionment and spatial variability

“…Similar high non-fossil contributions to OC were also found in previous studies in Switzerland. The f NF,OC values for ZUR, ROV, MOL, REI and Sedel as well as MAS, Saxon, Sion and Brigerbad ranged on average from 61-76 % with values above 90 % in ROV Sandradewi et al, 2008a, b;Perron et al, 2010). Results previously reported for other regions in Europe show lower biomass burning contributions to OC: e.g., biomass burning OC (OC BB ) to the total OC fraction of 35-54 % at three Austrian cities (Vienna, Graz and Salzburg, Caseiro et al, 2009), 28-65 % at three locations in the Po Valley (Milan, Sondrio and Ispra, Gilardoni et al, 2011;Piazzalunga et al, 2011b) and 60 % in Grenoble .…”

“…All samples were combusted following the thermaloptical transmittance method (TOT) using the EUSAAR2 temperature protocol (Cavalli et al, 2010). It should be noted here that the OC / EC determination with TOT instruments is not standardized yet and that measurements with different thermal protocols (e.g., NIOSH NIOSH, 1999;Peterson and Richards, 2002), IMPROVE (Chow et al, 1993), EUSAAR2 (Cavalli et al, 2010) may lead to discrepancies. Typically, total carbon (TC) measured with different protocols shows good agreement (within 10 %), whereas EC can differ significantly from method to method, up to 25 %, and for highly polluted winter samples even up to 60 % , Schmid et al, 2001Piazzalunga et al, 2011a).…”

“…Levoglucosan was measured following the procedures described in Piazzalunga et al (2010) and(2013a). In brief, levoglucosan was measured by a high-performance anionexchange chromatography (HPAEC) with pulsed amperometric detection (PAD) using an ion chromatograph (Dionex ICS1000) equipped with an isocratic pump and a sample injection valve with a 100 µL sample loop.…”

Residential Wood Burning: A Major Source of Fine Particulate Matter in Alpine Valleys in Central Europe

“…These stations appear in Table 1 repeatedly. (a) [14], only winter data (the mannosan data, not shown in the paper, was determined together with levoglucosan as described in the manuscript), (b) [46], (c) [13], (d) [54], (e) [53], (f) [15], (g) [8], (h) [16], (i) [43], (j) [65], (jj) [66], (k) [10], (l) [55], (m) [56], (n) [47,48], (o) [44], (p) [41], (q) [57], (r) [58] 3.2.1 PM from WB Figure 2a provides the average contribution of wood burning emissions to PM as listed in Table 1. The absolute contributions of PM wb show a very wide range from 0.4 μg m À3 at a remote site in Northern Italy to 35.1 μg m À3 at a site in the French Alps that is highly impacted by wood burning emissions.…”