Polar aerosols

During the winter and early spring (February to April) the Arctic aerosol has been found to be influenced significantly by anthropogenic sources, and the phenomenon is commonly referred to as Arctic haze (Barrie 1986). During this period the aerosol number concentration increases to over 200 cm-3. The nucleation mode mean diameter is at 0.05 pm and the accumulation mode at 0.2 pm (Covert and Heintzenberg 1993) 

FIGURE 8.21 Comparison of the aerosol distribution during Arctic haze with the typical polar distribution. 

The polar aerosol contains carbonaceous material from midlatitude pollution sources, sulfate, seasalt from the surrounding ocean, and mineral dust from arid regions of the corresponding hemisphere. Aerosol PM10 concentrations in the polar regions are less than 5 pg m-3 with sulfate representing roughly 40% of the mass. 

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POLDER Polarization and Directionality of the Earth s Radiance TR Polarization, aerosols, clouds ADEOS-1 (1996-97)... 

Fig. 3. Number density of polar aerosol, a) South Pole b) Bartow, Alaska.

Polar aerosols, found close to the surface in the Arctic and Antarctica, reflect their aged character their concentrations are very low. Collections of data from aerosol measurements in the Arctic have been presented by a number of investigators (Rahn 1981 Shaw 1985 Heintzenberg 1989 Ottar 1989). The number distribution appears practically monodisperse (Ito and Iwai 1981) with a mean diameter of approximately 0.15 pm two more modes at 0.75 and 8 pm (Shaw 1986 Jaenicke et al. 1992) (Figure 8.20) dominate the mass distribution. 

FIGURE 7.20 Typical polar aerosol number, surface, and volume distributions. 

Polar aerosols that occur in the areas of the Arctic and the Antarctica. These aerosols are usually of low concentration and relatively close to the ground. Several regions of earth s atmosphere are identified based on the way temperature changes with altitude. Typically, atmospheric temperature decreases with increasing altitude in the troposphere (from 0 to 7—20 km) until it reaches a minimum of about at -50 C at an altitude called the tropopause. Meteorology is the science of the troposphere, the lower atmosphere. 

The ablated vapors constitute an aerosol that can be examined using a secondary ionization source. Thus, passing the aerosol into a plasma torch provides an excellent means of ionization, and by such methods isotope patterns or ratios are readily measurable from otherwise intractable materials such as bone or ceramics. If the sample examined is dissolved as a solid solution in a matrix, the rapid expansion of the matrix, often an organic acid, covolatilizes the entrained sample. Proton transfer from the matrix occurs to give protonated molecular ions of the sample. Normally thermally unstable, polar biomolecules such as proteins give good yields of protonated ions. This is the basis of matrix-assisted laser desorption ionization (MALDI). 

In the past few years, a range of solvation dynamics experiments have been demonstrated for reverse micellar systems. Reverse micelles form when a polar solvent is sequestered by surfactant molecules in a continuous nonpolar solvent. The interaction of the surfactant polar headgroups with the polar solvent can result in the formation of a well-defined solvent pool. Many different kinds of surfactants have been used to form reverse micelles. However, the structure and dynamics of reverse micelles created with Aerosol-OT (AOT) have been most frequently studied. AOT reverse micelles are monodisperse, spherical water droplets [32]. The micellar size is directly related to the water volume-to-surfactant surface area ratio defined as the molar ratio of water to AOT,... 

M. Murozumi, Tsaihwa J. Chow, and C. Patterson. Chemical Concentrations of Pollutant Lead Aerosols, Terrestrial Dusts and Sea Salts in Greenland and Antarctic Snow Strata. Geochimica et Cosmochimica Acta. 33 (Oct. 1969) 1247-1294. Source for details of polar field trips. 

Clair C. Patterson, T. J. Chow, and M. Murozumi. The Possibility of Measuring Variations in the Intensity of Worldwide Lead Smelting during Medieval and Ancient Times Using Lead Aerosol Deposits in Polar Snow Strata. In Scientific Methods in Medieval Archaeology. Rainer Berger, ed. Berkeley University of California Press, 1970, pp. 339-350. 

P. E. Zinsli, Inhomogeneous interior of aerosol OT microemulsions probed by fluorescence and polarization decay,/. Phys. Chem. 83, 3223-3231 (1979). 

The pure electrospray process of dispersing a liquid into an aerosol works best at flow rates of 1-20 pi min" Conventional unassisted ESI has also limitations as a LC-MS interface due to the solvent properties in terms of volatility and polarity which can be electrosprayed without some type of assistance. Therefore, a number of sprayer modifications including a heated sprayer [55] have been developed to expand the range of ESI applications (Fig. 11.4). 

The aerosol and gaseous lead that has settled onto polar ice eventually becomes buried. Thus, ice cores provide an excellent chronological record of lead inputs as shown in Figure 28.25. Humans began smelting lead ores dates back to at least 5000 BC and can be detected in the ice core record. Lead production increased significantly at the start... 

In order to test further the applicability of 1-pyrene carboxaldehyde as a fluorescent probe, we applied Keh and Valeur s method (4) to determine average micellar sizes of sulfonate A and B micelles. This method is based on the assumption that the motion of a probe molecule is coupled to that of the micelle, and that the micellar hydrodynamic volumes are the same in two apolar solvents of different viscosities. For our purposes, time averaged anisotropies of these systems were measured in two n-alkanes hexane and nonane. The fluorescence lifetime of 1-pyrene carboxaldehyde with the two sulfonates in both these solvents was found to be approximately 5 ns. The micellar sizes (diameter) calculated for sulfonates A and B were 53 5A and 82 lOA, respectively. Since these micelles possesed solid polar cores, they were probably more tightly bound than typical inverted micelles such as those of aerosol OT. Hence, it was expected that the probe molecules would not perturb the micelles to an extent which would substantially affect the micellar sizes measured. 

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