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| Home > Publications database > Lagrangian particle dispersion modeling of stable carbon isotope ratios to track the chemical aging of biomass burning aerosol |
| Master Thesis | FZJ-2020-00428 |
2019
Please use a persistent id in citations: http://hdl.handle.net/2128/24788
Abstract: Biomass burning is an important source of atmospheric pollutants in gas and particulate phase.These have an impact on air quality, health and climate. Domestic heating with firewood is amajor source of fine dust in Germany in the cold season. So there is a strong scientific interestto accurately quantify the contribution of local to remote sources to the aerosol burden.In this work, a modeling methodology is developed to simulate concentration and isotoperatios of the biomass burning tracer levoglucosan. To this end, retroplumes obtained withthe Lagrangian Particle Dispersion Model (LPDM) FLEXPART are folded with country-specificemission inventories. Since isotopes can provide additional information on source and processingof the sampled aerosol, the option to output stable carbon isotope ratios of levoglucosan isimplemented in the model. Sensitivity studies are conducted to determine governing processes inthe employed model. Furthermore, the established modeling routines are applied in a case study,with the goal to assess the contribution of local vs. remote emissions from firewood domesticheating to the particulate matter sampled at two measurement stations of the North Rhine-Westphalia Landesumweltamt (LANUV). This study focuses on 50 selected aerosol samplestaken at an urban background station in Mülheim-Styrum and at a rural background stationin the Eifel, in the cold seasons of 2015 - 2017. The measured concentration and isotopiccomposition of the sampled levoglucosan are used to validate the modeling method.The results show a good agreement between modeled and observed concentrations. It isthough shown that at the urban station, concentration measurements are partly influenced byunresolved sources near by the sampling station. According to the model outcome, the largestpart of the sampled aerosol is 1 - 2 days old, and thus originates from local to regional sources.Consequently, chemical aging has a minor influence on the levoglucosan concentration andisotopic composition in the modeled period. Additionally to the short atmospheric residencetime, a low OH-concentration in the cold season hinders chemical decay. On that account, itcan be concluded that the observed -value variances are caused only by variances in the isotoperatios at sources. The sensitivity studies indicate that the main sink for the investigated biomassburning aerosol is wet deposition. For aged aerosol in the coarse mode, also gravitational settlingis a considerable loss process.This work shows that combining Lagrangian modeling with isotopic- and concentration measurements,reliable information on the biomass burning aerosol source is provided. The findingsshow that the biomass burning aerosol burden in living areas is of local origin and thus it can bemitigated by reducing local emissions. Yet, a comprehensive benchmarking of source specificisotopic ratios is still missing. Furthermore, modeling studies investigating large scale fires insummer are required, since they have the potential to contribute to aging understanding.
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