(NAS Colloquium) Geology, Mineralogy, and Human Welfare (1999) / Chapter Skim
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Airborne Minerals and Related Aerosol Particles: Effects on Climate and the Environment
Airborne Minerals and Related Aerosol Particles: Effects on Climate and the Environment
Pages 3372-3379
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From page 3372... ...
However, it is the individual chemical species that affect the radiative balance and Abbreviations: CCN, cloud condensation nuclei; TEM, transmission electron microscope; SEMI scanning electron microscope; MBL' marine boundary layer; FI,7 free troposphere; NSS7 non-sea salt; AFM' atomic force microscopy; ACE, Aerosol Characterization Experiments; FELINE' experiments in the equatorial Pacific; ASTEX/ IMAGE, experiments in the North Atlantic.
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From page 3373... ...
Hygroscopic materials such as sulfates and sea salts are especially efficient as nuclei; mineral dust and combustion products can also be effective, especially if they are wettable or acquire hygroscopic coatings (26~. Increased numbers of CCN lead to more cloud droplets and concurrent decreases in droplet sizes (for given cloud water contents)
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From page 3374... ...
Particle analysis using TEMs, which are the main instruments used for the results reported here, cannot be automated because of the complexity of the method (sample tilting in diffraction mode to obtain critical crystal orientation, combined with changes to imaging and analysis modes to obtain size, shape, and chemical information)
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From page 3375... ...
Soot/sulfate aggregates comprise about 20~o of all sulfate particles in two samples that we studied from Izana (ACE-24. Because we observed similar relative numbers of soot/sulfate internal mixtures in the aerosol from two essentially clean but geographically distant locations (Southern Ocean and Izana, North Atlantic)
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From page 3376... ...
It had been thought that sea-salt particles are mostly too large to be efficient scatterers of solar radiation and that the smaller NSS sulfate is the main contributor to radiative effects in the MBL. However, recent data indicate that in some regions sea salt can be a major source of CCN and can even dominate NSS sulfate (21, 70~.
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From page 3377... ...
Drought and increased desertification by human activities can dramatically increase the dust available for deflation, and the tropospheric dust burden will increase appreciably. The relatively short atmospheric lifetime of much such dust means its radiative forcing adjusts relatively rapidly to changes in emissions.
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From page 3378... ...
The observation of internal or external mixtures is important for determining which chemical reactions take place on mineral surfaces and how the original particles change during atmospheric transport. The compositions and aggregations of the mineral aerosols collected when a polluted air mass of European origin arrived at our sampling site near the Azores Islands reflect their transport over the ocean.
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From page 3379... ...
(1992) in Minerals and Reactions at the Atomic Scale: Transmission Electron Microscopy, ed.
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