Development of improved sampling and analysis methods for measuring organic, elemental, and water-soluble organic carbon in atmospheric aerosols and application to aerosol studies in Europe and tropical/equatorial and oceanic regions

• Main Author: Chi, Xuguang
• Other Authors: Maenhaut, Willy
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Ghent University. Faculty of Sciences 2009
• Subjects: Chemistry; sampling artefacts; particulate mass; in-situ measurements; aerosol sources; Indian; Amsterdam Island
• Online Access: https://biblio.ugent.be/publication/804813; http://hdl.handle.net/1854/LU-804813; https://biblio.ugent.be/publication/804813/file/4335107

The work conducted in this thesis had the following objectives: (1) to develop improved methods for a better discrimination between organic and elemental carbon (OC and EC) using the thermal-optical transmission (TOT) technique; (2) to deploy improved collection procedures for carbonaceous aerosols, whereby the sampling artifacts are better controlled or can be corrected for; (3) to perform detailed carbonaceous aerosol characterisation studies in Belgium and at urban and forested sites throughout Europe and (4) in the Brazilian Amazon basin, the tropical Atlantic Ocean, and at Amsterdam Island in the Indian Ocean. With regard to objective (1), the OC/EC split in three different temperature programs was examined for samples from widely different origins. This study confirmed that the OC/EC split in TOT depends upon the temperature program used, particularly that in the first phase of the analysis (in pure He). As to objective (2), a denuded sampling setup (with upstream of the filter holder with two quartz fibre filters a denuder for volatile organic compounds and oxidising inorganic gases) and the tandem filter method (with two quartz fibre filters in series without denuder) were used in parallel for low-volume PM2.5 collections in several campaigns since 2002. It was found that subtracting the back filter OC from the front filter OC yields “artifact-free” particulate OC data. With regard to objective (3), the median PM2.5 EC concentrations at our various sites in Europe ranged from 0.07 μg/m3 in the 2007 campaign at Hyytiälä, Finland, to 3.3 μg/m3 during the 2002 campaign at a kerbside site in Budapest. There was a general increasing trend for EC levels from forested sites, to urban sites, and to kerbside sites, reflecting the increasing impact of local anthropogenic emissions, especially those from traffic. For OC, however, there was no clear spatial trend. As to objective (4), the OC and EC data from a 2006 oceanic cruise in the northern hemisphere contrasted substantially with those found for Amsterdam ...