AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Morphological and Elemental Classification of Long-range Transported Fine and Ultrafine Particles by STEM-EDX Individual Particle Analysis
SHILA MASKEY, Hoseung Chae, Kihong Park, GIST
Abstract Number: 559 Working Group: Urban Aerosols
Abstract Fine (<2.5 µm) and ultrafine (<100 nm) ambient particles affect radiation balance, cloud formation, visibility impairment, and result possibly an adverse health consequence. The mass concentrations, size, composition and sources of the particles in certain urban areas are strongly affected by long-range transport. During long-range transport, particles could change their properties due to coagulation, cloud processes, condensation or reactions with air pollutants by various heterogeneous pathways. Because of their diverse sources and formation pathways, the particle consists of various chemical constituents with different morphology. In this study, the elemental compositions, morphologies and mixing states of individual aerosol particles in two size fractions were analyzed using scanning transmission electron microscopy coupled with energy dispersive X-ray (STEM-EDX) technique.
The long-range transport particle (LTP) event in Korea was identified by 72-h backward air mass trajectory and PM mass concentration data. Aerosol samples were collected during LTP event (18-19 March, 2014) from the terrace of Gwangju institute of science and technology (GIST) campus (35:13N, 126:50E), Gwangju, which is surrounded by a residential, industrial, and agricultural area. Fine and ultrafine particles were collected on copper TEM grids using PM$_(2.5) impactors and nanometer aerosol sampler (TSI, 3089, USA), respectively. Approximately 430 measured particles in the LTP event of samples were mainly classified into carbonaceous, mineral dust, volatile inorganic, heavy metal-containing, and fly ash particles based on their morphology and X-ray spectral data. Among the particle types, carbonaceous particles were categorized into: soot, semi-volatile organic, non-volatile organic, biogenic, and biomass burning particles. Many of the particles in both size fraction samples were internally mixed with S, N and/ or C. For comparison, the analysis of aerosol samples collected during non-event (25 June, 2014) day is being carried out.