Project at a Glance
Title: Thermodynamics of organic atmospheric aerosols.
Principal Investigator / Author(s): Seinfeld, John H.
Contractor: California Institute of Technology
Contract Number: 98-314
Research Program Area: Atmospheric Processes
Topic Areas: Modeling
Organic species are an important component of atmospheric particles. Particulate organic compounds, suspected to be a possible source of human health effects in inhaled particles, arise from both direct emissions and gas-to-particle conversion in the atmosphere. Those arising from gas-to-particle conversion, so-called secondary organic aerosols, transfer to particles based on equilibrium partitioning between the gas and particle phases. The ability to represent that partitioning is central to atmospheric models that can be used to predict organic aerosol levels. The goal of this project is to develop a general organic gas-particle partitioning model
appropriate for use in three-dimensional atmospheric models and apply it to predict organic aerosol levels in the South Coast Air Basin. The partitioning model divides semi-volatile organic species (those with sufficiently low vapor pressure to condense, at least in part, to the aerosol phase) into hydrophobic and hydrophilic categories and then computes the partitioning of those molecules to satisfy thermodynamic equilibrium and total mass conservation.
For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893
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