Measurement and Characterization of Semi-Volatile and Particulate Organics and their Dynamic Behavior
The objectives of this project are: 1) to develop, validate and apply new measurement methods for accurate determination of semivolatile organic pollutants in ambient air and combustion sources; and 2) to assess the impact of measurement uncertainty on predicted global behavior of persistent organic pollutants such as polycyclic organic hydrocarbons, chlorinated pesticides and dioxins.
Such semi-volatile species partition between the gas and particle phases in ways that complicate apportionment efforts. The innovative measurement technology developed at LBNL by this project is contributing to several multi-investigator studies whose goal is to characterize carbonaceous particles across the U.S.
At the core of this measurement technology is one of the year 2000's R&D 100 Award winners, LBNL's Fine XAD Sorbent Coating. This photomicrograph shows the sub-micron sized particles on etched glass.
The new sorbent has revolutionized the sampling of airborne particles. Diffusion-based denuders or samplers that incorporate the Fine XAD Sorbent Coating (such as LBNL's Integrated Organic Gas and Particle Sampler or IOGAPS) minimize the measurement errors that are associated with conventional filter/sorbent samplers. Research groups around the U.S. are employing this sampling technology in studies of semi-volatile organic compounds. Among these studies have been investigations of the atmospheric behavior of dioxins and the contribution of diesel, other vehicle exhausts, and wood smoke to smog formation (under different weather conditions, in different parts of the country, and at different times of the day or night). Diffusion denuders with LBNL's coating are currently being used extensively as part of the nationwide effort to characterize pollution particles.
A significant emerging application is the use of the sorbent coating on fabric filters for replacement of conventional sorbents in air samplers. Because the coated filters can be analyzed directly, this approach offers substantial reductions in operator effort and solvent and power consumption, with improved accuracy. In addition, this coating will be instrumental in creating new, "active" surfaces, with potential applications not only in pollution monitoring, but also in indoor climate control, ventilation and real-time instruments and sensors.
Below is the photo of the cross section of a coated annular denuder that appeared in the September 2000 issue of R&D magazine.
We are participating in the exposure assessment and source apportionment efforts of the Northwest Center for the Study of the Health Effects of Particulate Matter. We are contributing to understanding the links between PM and health effects by clarifying the role of SVOC in PM exposure. We are applying our new sampling and improved analytical methods to yield better SVOC and PM exposure assessment and source apportionment by:
Contact: Lara Gundel