1Joint Mass Spectrometry Centre (JMSC), Cooperation Group "Comprehensive Molecular Analytics" (CMA), Helmholtz Zentrum München, München, 81379, Germany
2Joint Mass Spectrometry Centre (JMSC), Chair of Analytical Chemistry, University of Rostock, Rostock, 18059, Germany
3Empa, Laboratory for Air Pollution/Environmental Technology, Dübendorf, Switzerland
4Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, 119991, Russian Federation
5Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan
6Department of Environmental Sciences, University of Basel, Basel, 4056, Switzerland
7Hydro-Meteorological Observation Center, Vietnam Meteorological and Hydrological Administration, Ministry of Natural Resources and Environment, Ha Noi, Vietnam
8Institute of Geophysics, Vietnam Academy of Science and Technology (VAST), Ha Noi, Vietnam
anow at: Mobile Source Laboratory Division, California Air Resource Board, El Monte, CA 91731, United States
1Joint Mass Spectrometry Centre (JMSC), Cooperation Group "Comprehensive Molecular Analytics" (CMA), Helmholtz Zentrum München, München, 81379, Germany
2Joint Mass Spectrometry Centre (JMSC), Chair of Analytical Chemistry, University of Rostock, Rostock, 18059, Germany
3Empa, Laboratory for Air Pollution/Environmental Technology, Dübendorf, Switzerland
4Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, 119991, Russian Federation
5Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan
6Department of Environmental Sciences, University of Basel, Basel, 4056, Switzerland
7Hydro-Meteorological Observation Center, Vietnam Meteorological and Hydrological Administration, Ministry of Natural Resources and Environment, Ha Noi, Vietnam
8Institute of Geophysics, Vietnam Academy of Science and Technology (VAST), Ha Noi, Vietnam
anow at: Mobile Source Laboratory Division, California Air Resource Board, El Monte, CA 91731, United States
Received: 02 Oct 2020 – Accepted for review: 25 Oct 2020 – Discussion started: 28 Oct 2020
Abstract. We investigated concentrations of organic carbon (OC), elemental carbon (EC) and a wide range of particle-bound organic compounds in daily sampled PM2.5 at the remote Pha Din (PDI) – Global Atmosphere Watch (GAW) monitoring station in Northwestern Vietnam during an intense 3-week sampling campaign from 23rd March to 12th April 2015. The site is known to receive trans-regional air masses during large-scale biomass burning episodes, but OC composition studies are missing in the scientific literature. We quantified 51 organic compounds simultaneously by in-situ derivatization thermal desorption gas chromatography time-of-flight mass spectrometry (IDTD-GC-TOFMS). Anhydrosugars, methoxyphenols, n-alkanes, fatty acids, polycyclic aromatic hydrocarbons, oxygenated polycyclic aromatic hydrocarbons, nitrophenols as well as OC were used in a hierarchical cluster analysis highlighting distinctive patterns for periods under low, medium and high biomass burning (BB) influence. The highest particle phase concentration of the typical primary organic aerosol (POA) and possible secondary organic aerosol (SOA) constituents, especially nitrophenols, were found on 5th and 6th April. We linked the trace gases CH4, CO2, CO, O3 mixing ratios to the statistical classification of BB events based on OA composition and found increased CO and O3 levels during medium and high BB influence. Likewise, a backward trajectory analysis indicates different source regions for the identified periods based on the OA cluster, with cleaner air masses arriving from northeast, i.e., mainland China and Yellow sea. The more polluted periods are characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia cannot only significantly enhance the regional organic aerosol loading, but also affect the carbonaceous PM2.5 constituents and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on the carbonaceous and in particular OC chemical composition of PM2.5 in a region of scarce data availability.
Southeast Asia is well-know for emission-intense and recurring wildfires and after-harvest crop residue burning during pre-monsoon season from February to April. We describe a biomass burning (BB) plume arriving at remote Pha Din meteorological station, outline its carbonaceous particulate matter (PM) constituents based on more than 50 target compounds and discuss possible BB sources. This study add valuable information on chemical PM composition for a region with scarce data availability.
Southeast Asia is well-know for emission-intense and recurring wildfires and after-harvest crop...