Organic aerosol is a large and important fraction of PM1 and has great impact on human health, especially because of some of the compounds have proved to be mutagens or carcinogens. Along with fast economical growth, the air quality in Beijing has suffered severe deterioration, with PM being one of the top pollutants.
Organic matter is the most abundant fraction in fine particles in Beijing, accounting for 30-50% of the total mass, indicating its key role in air pollution control. Because the chemical compositions and sources of OA are complex (they can be classified as either primary OA (POA), from direct emissions, or secondary OA (SOA), from the oxidation of gas-phase precursors), the related studies on their chemical and physical characteristics have become difficult and a recent focus point. High time-resolution online measurements are needed to gain insight into aerosol chemical characteristics, sources and processes.
Professor Wang Yuesi and Dr. Liu Quan from State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences performed the online observation of chemical compositions and size distributions of OA with a HR-ToF-AMS to reveal the variation regularity of organic aerosols in Bejing winter. Meanwhile, based on the data of the mass spectra of organic compounds, major sources of OA were resolved by positive matrix factorisation (PMF). Their work, entitled "In situ measurement of PM1 organic aerosol in Beijing winter using a high-resolution aerosol Mass Spectrometer", was published in Chinese Science Bulletin, 2012, Vol 57(7).
The mean OA mass concentration was 20.9±25.3 ìg/m3 during this campaign, varying between 1.9 and 284.6 ìg/m3. The average mass-based size distributions of OA present a prominent accumulation mode peaking at approximately 450 nm. During this study, the average H/C, O/C and N/C (molar ratio) were 1.70, 0.17, and 0.005, respectively, corresponding to an OM/OC ratio (mass ratio of organic matter to organic carbon) of 1.37. The diurnal pattern of O/C was consistent with that of OM/OC and displayed a typical photochemical characteristic.
Positive Matrix Factorisation (PMF) analysis of the organic mass spectral dataset differentiated the OA into three components (Figure 1): hydrocarbon-like (HOA), cooking-related (COA), and oxygenated (OOA) organic aerosols, which, on average, accounted for 26.9%, 49.7% and 23.4%, respectively. The sum of HOA and COA could be regarded as POA, and the OOA corresponded to aged SOA. The POA is a dominant component of OA in Beijing winter, with a large percentage of 76.6%. The large contribution of COA in the POA mass indicates its key role in PM1 pollution control in Beijing.
See the article: Liu Quan, Sun Yang, Hu Bo et al. In situ measurement of PM1 organic aerosol in Beijing winter using a high-resolution aerosol Mass Spectrometer. Chinese Science Bulletin, 2012, 57 (7): 819-826.
Liu Quan | EurekAlert!
Wintertime Arctic sea ice growth slows long-term decline: NASA
07.12.2018 | NASA/Goddard Space Flight Center
Why Tehran Is Sinking Dangerously
06.12.2018 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.
The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
10.12.2018 | Life Sciences
10.12.2018 | Physics and Astronomy
10.12.2018 | Life Sciences