Characterization of Aerosol Organic Matter: Detection, Formation, Optical and Radiative Effects

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Characterization of Aerosol Organic Matter
Detection, Formation, Optical and Radiative
Effects

• Yin-Nan Lee
• Atmospheric Sciences Division
• Brookhaven National Laboratory

ASP Science Team Workshop Charleston, SC January
25, 2005
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Research Objectives

• To develop a real-time TOC measurement technique
  suitable for aircraft deployment that can also
  quantify the WSOC.
• To determine aerosol chemical composition,
  including TOC and WSOC, as well as inorganic ions
  during field campaigns.
• To investigate the relationships between TOC and
  WSOC and their precursors.
• To determine the rate of SOA formation and its
  connection to photochemical reactions of VOCs.
• To identify the mechanisms important to SOA
  formation, including the acid catalyzed
  reactions.
• To characterize the humic like substances (HULIS)
  in terms of size, sources and formation
  mechanisms.
• To evaluate the contributions of organic
  components to aerosols optical and radiative
  effects.

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Knowledge of chemical composition is the key to
understanding many aerosol properties
Atmospheric Distributions
Physical and Chemical Properties

• Sources
• Formation mechanisms
• Size distributions
• Life times

• Light extinction
• Scattering
• absorption
• Hygroscopicity
• Size dependence on RH
• Cloud condensation nuclei property
• Air quality and health effects

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Major Chemical Components of Ambient Aerosol
Particles
Inorganic
Organic

• Sulfate, nitrate, phosphate, chloride
• Ammonium, sodium, potassium, calcium, magnesium
• Aluminum, cadmium, iron, lead, silicon
• Black carbon

• Alkanes, alkanols, alkanoic acids, diacids,
  ketoacids
• Polycyclic aromatic hydrocarbons (PAHs)
• Alkenes and aldehydes
• Pesticides/PCBs
• Polyols, carbohydrates
• Humic like substances (HULIS)

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Major Classes of Aerosol Organic Compoundsand
Their Sources
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Specific Questions to be Addressed in this
Research
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Research Plane
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Aerosol NH4 and SO4 concentrations and light
scattering coefficient during a power plant plume
study, 8/9/04, NEAX
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Some aerosol properties observed during the
8/9/04 power plant plumes study, NEAX
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Anticipated Output of Research

• Source identification of organics (in association
  with black carbon and VOC distributions).
• Formation mechanisms of SOC (absorption vs
  on-particle reactions).
• Contributions of organics to aerosol mass,
  hygroscopicity and light scattering.
• Effects to cloud condensation nuclei properties.
• Improved understanding of HULIS.
• Aid the interpretation of AMS data.
• Help to understand the OCEC measurement.

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Deliverables
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Deliverables
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Relationships to Other ASP Projects

• Size distribution OPC, DMA
• Light scattering Nephelometer
• Light absorption Aethalometer
• f(RH) based on, e.g., bsp
• CCN concentration
• Total carbon OCEC
• VOC and photochemistry
• Aerosol optical depth
• Air back trajectories
• Meteorological data, e.g., T, RH, wind directions
  and speed

• Chemical composition
• SO4, NO3, NH4, K, Ca, Mg, Na, Cl
• Formate, acetate, oxalate
• TOC, WSOC, HULIS
• Source Identification
• Process Evaluation
• Optical properties
• Scattering, absorption, and single scattering
  albedo
• CCN properties

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Humic Like Substances (HULIS)
Polymeric substances comprising of alkanoic and
benzenecarboxylic acids molecular weight 200
1000 similar to humic acids in UV, IR, NMR
characters possible mechanisms include in-cloud
OH mediated reactions.

• Sampling
• Filter based
• Extraction into an aqueous solution
• Identification
• Size exclusion chromatography using sephadex
  packing
• Using either UV absorption or refractive index
  detectors
• Background information
• OCEC
• PILS-TOC
• Air back trajectory to identify the role of cloud
  processing

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Aerosol concentrations (ng m-3) of OC, EC,
polyhydroxylated, and mono- and
dihydroxydicarboxylic acids during a LBA-CLAIRE
wet season campaign in Balbina, Brazil, 2001. The
percent carbon contributions to the OC are given
in parentheses. Claeys et al., Science, 303,
1173 (2004).
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Kavouras et al., Environ. Sci. Technol., 33,
1028, 1999.
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Gas-Particle Partition of organic compounds
Absorption
e.g., Seinfeld and Pankow, Annu. Rev. Phys.
Chem., 54, 121 (2003)
Liang et al., EST, 31, 3086 (1997)
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High vapor pressure aldehydes show major
deviations
Jang and Kamens, EST, 35, 3626 (2001).
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a-Pinene reaction products show significantly
higher partition coefficients than predicted.
Lee, Jang, and Kamens, Atmos. Environ., 38, 2597
(2004)
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Acid catalyzed reactions of atmospheric carbonyls
in aerosol particles Jang et al., Science, 298,
814 (2002).
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In-cloud formation of oxalic acid Warneck,
Atmos. Environ., 37, 2423 (2003)
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Principle of the Sievers TOC Analyzer
Conductivity cell
MEMBRANE MODULE
MEMBRANE MODULE
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Calibration of the Sievers TOCD using Na2CO3
(left) and resorcinol (right)

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