21 research outputs found
A 1-year aerosol chemical speciation monitor (ACSM) source analysis of organic aerosol particle contributions from anthropogenic sources after long-range transport at the TROPOS research station Melpitz
Atmospheric aerosol particles are a complex combination of primary emitted
sources (biogenic and anthropogenic) and secondary aerosol resulting from
aging processes such as condensation, coagulation, and cloud processing. To
better understand their sources, investigations have been focused on urban
areas in the past, whereas rural-background stations are normally less
impacted by surrounding anthropogenic sources. Therefore, they are
predisposed for studying the impact of long-range transport of anthropogenic
aerosols. Here, the chemical composition and organic aerosol (OA) sources of
submicron aerosol particles measured by an aerosol chemical speciation
monitor (ACSM) and a multi-angle absorption photometer (MAAP) were
investigated at Melpitz from September 2016 to August 2017. The location of
the station at the frontier between western and eastern Europe makes it the
ideal place to investigate the impact of long-range transport over Europe.
Indeed, the station is under the influence of less polluted air masses from
westerly directions and more polluted continental air masses from eastern
Europe. The OA dominated the submicron particle mass concentration and
showed strong seasonal variability ranging from 39 % (in winter) to 58 % (in summer). It was followed by sulfate (15 % and 20 %) and
nitrate (24 % and 11 %). The OA source identification was performed
using the rolling positive matrix factorization (PMF) approach to account
for the potential temporal changes in the source profile. It was
possible to split OA into five factors with a distinct temporal variability
and mass spectral signature. Three were associated with anthropogenic
primary OA (POA) sources: hydrocarbon-like OA (HOA; 5.2 % of OA mass in
winter and 6.8 % in summer), biomass burning OA (BBOA; 10.6 % and 6.1 %) and coal combustion OA (CCOA; 23 % and 8.7 %). Another two are
secondary and processed oxygenated OA (OOA) sources: less oxidized OOA (LO-OOA;
28.4 % and 36.7 %) and more oxidized OOA (MO-OOA; 32.8 % and 41.8 %). Since equivalent black carbon (eBC) was clearly associated with the
identified POA factors (sum of HOA, BBOA, and CCOA; R2= 0. 87), eBC's
contribution to each of the POA factors was achieved using a multilinear
regression model. Consequently, CCOA represented the main anthropogenic
sources of carbonaceous aerosol (sum of OA and eBC) not only during winter
(56 % of POA in winter) but also in summer (13 % of POA in summer),
followed by BBOA (29 % and 69 % of POA in winter and summer,
respectively) and HOA (15 % and 18 % of POA in winter and summer,
respectively). A seasonal air mass cluster analysis was used to understand
the geographical origins of the different aerosol types and showed that
during both winter and summer time, PM1 (PM with an aerodynamic
diameter smaller than 1 µm) air masses with eastern influence were
always associated with the highest mass concentration and the highest coal
combustion fraction. Since during wintertime CCOA is a combination of
domestic heating and power plant emissions, the summer contribution of CCOA
emphasizes the critical importance of coal power plant emissions to
rural-background aerosols and its impact on air quality, through long-range
transportation.</p
European aerosol phenomenology - 8 : Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets
Organic aerosol (OA) is a key component of total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013-2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables quantification of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30-240 min) and long-term data coverage (9-36 months), providing essential information to improve/validate air quality, health impact, and climate models.Peer reviewe
Social Media, Gender and the Mediatisation of War: Exploring the German Armed Forces’ Visual Representation of the Afghanistan Operation on Facebook
Studies on the mediatisation of war point to attempts of governments to regulate the visual perspective of their involvements in armed conflict – the most notable example being the practice of ‘embedded reporting’ in Iraq and Afghanistan. This paper focuses on a different strategy of visual meaning-making, namely, the publication of images on social media by armed forces themselves. Specifically, we argue that the mediatisation of war literature could profit from an increased engagement with feminist research, both within Critical Security/Critical Military Studies and within Science and Technology Studies that highlight the close connection between masculinity, technology and control. The article examines the German military mission in Afghanistan as represented on the German armed forces’ official Facebook page. Germany constitutes an interesting, and largely neglected, case for the growing literature on the mediatisation of war: its strong antimilitarist political culture makes the representation of war particularly delicate. The paper examines specific representational patterns of Germany’s involvement in Afghanistan and discusses the implications which arise from what is placed inside the frame of visibility and what remains out of its view
Simulation of business processes in an enterprise modelling system
Peer reviewed: YesNRC publication: Ye
Process modelling for intelligent manufacturing systems
Peer reviewed: YesNRC publication: Ye