Assessing the Influence of Seasonal and Spatial Variations on the Estimation of Secondary Organic Carbon in Urban Particulate Matter by Applying the EC-Tracer Method

Abstract

Abstract:The elemental carbon (EC)-tracer method was applied to PM 10 and PM 1 data of three sampling sites in the City of Berlin from February to October 2010. The sites were characterized by differing exposure to traffic and vegetation. The aim was to determine the secondary organic carbon (SOC) concentration and to describe the parameters influencing the application of the EC-tracer method. The evaluation was based on comparisons with results obtained from positive matrix factorization (PMF) applied to the same samples. To obtain site-and seasonal representative primary OC/EC-ratios ([OC/EC] p ), the EC-tracer method was performed separately for each station, and additionally discrete for samples with high and low contribution of biomass burning. Estimated SOC-concentrations for all stations were between 11% and 33% of total OC. SOC-concentrations obtained with PMF exceeded EC-tracer results more than 100% at the park in the period with low biomass OPEN ACCESSAtmosphere 2014, 5 253 burning emissions in PM 10 . The deviations were besides others attributed to the high ratio of biogenic to combustion emissions and to direct exposure to vegetation. The occurrences of biomass burning emissions in contrast lead to increased SOC-concentrations compared to PMF in PM 10 . The obtained results distinguish that the EC-tracer-method provides well comparable results with PMF if sites are strongly influenced by one characteristic primary combustion source, but was found to be adversely influenced by direct and relatively high biogenic emissions.

Carbonaceous Aerosols in Contrasting Atmospheric Environments in Greek Cities: Evaluation of the EC-tracer Methods for Secondary Organic Carbon Estimation

“…Galindo et al [87] found annual-mean contributions (38%) of SOC to OC for PM 10 samples in urban Elche, Spain, whereas a 50% SOC fraction to OC mass of PM 2.5 and PM 10 samples was found in Lecce, Italy [88]. Conversely, estimated SOC concentrations of only 16-21% of OC mass in PM 10 samples were estimated at three sites in Berlin, Germany, for the BB-active period [89]. These findings indicate a north-south gradient in SOC contributions in Europe, related to climatic conditions favoring the generation or organic compounds that undergo gas-to-particle conversion.…”

Comparison of Measurement-Based Methodologies to Apportion Secondary Organic Carbon (SOC) in PM2.5: A Review of Recent Studies

“…Similarly to the North American continent, SOC estimates using the EC tracer method have been extensively performed throughout Europe [96,97,[122][123][124][125][126][127][128][129][130][131][132][133][134]. The annual and spring-summer average of SOC levels varied in the ranges 1.6-4.9 µgC m −3 and 0.90-4.4 µgC m −3 , contributing to 36-73% and 41-84% of PM 2.5 OC, respectively (Figures 2 and 3, Tables SA2 and SA3).…”