CLIMATE SCIENCE: The Shape They're In

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Science  20 Jan 2006:
Vol. 311, Issue 5759, pp. 305a
DOI: 10.1126/science.311.5759.305a

Soot, the product of the incomplete combustion of fossil fuels and biomass, is emitted in large quantities globally and is one of the more important climate-forcing agents added to the atmosphere. The radiative and chemical properties of soot particles depend largely on their shape, which generally is not well defined and hence is usually modeled as a sphere or an elongated cylinder.

In order to characterize the actual morphology of soot, van Poppel et al. have used electron tomography to determine shapes, volumes, and surface areas of clusters of soot nanoparticles. They find that the imaged surface areas and volumes can differ from the geometrically modeled values by one and two orders of magnitude, respectively. This result has important implications for the chemical aging of soot—the process of changing hydrophobic soot particles into a hydrophilic and more readily scavenged aerosol—which affects its atmospheric lifetime and its radiative forcing potency. — HJS

Geophys. Res. Lett. 32, 10.1029/2005GL024461 (2005).

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