Fog water

An ion chromatographic system that included column switching and gradient analysis was used for the deterrnination of cations such as Na", Ca ", Mg ", K", and NH" 4 and anions such as Cf, NO, NO , and in fog water samples (72). Ion-exchange chromatography compares very well with... 

Methyl parathion can be released to surface waters by storm runoff from sprayed fields atmospheric deposition following aerial application (wet deposition from rain and fog water) waste water releases from formulation, manufacturing, or processing facilities and spills. 

Atmospheric transport of atrazine-contaminated aerosol particulates, dusts, and soils may contribute significantly to atrazine burdens of terrestrial and aquatic ecosystems. The annual atmospheric input of atrazine in rainfall to the Rhode River, Maryland, as one example, was estimated at 1016 mg/surface ha in 1977, and 97 mg/ha in 1978 (Wu 1981). A similar situation exists with fog water. When fog forms, exposed plant surfaces become saturated with liquid for the duration of the fog (Glotfelty et al. 1987). 

Faust, B. C., and J. M. Allen, Aqueous-Phase Photochemical Formation of Hydroxyl Radical in Authentic Cloudwaters and Fog-waters, Environ. Sci. Technol., 27, 1221-1224 (1993). 

Hoffmann, M. R., and D. J. Jacob, Kinetics and Mechanisms of Catalytic Oxidation of Dissolved Sulfur Dioxide in Aqueous Solution An Application to Nighttime Fog Water Chemistry, in SO2, NO, and N02 Oxidation Mechanisms Atmospheric Considerations, Acid Precipitation Series, Vol. 3, pp. 101-172 (J. I. Teasley, Series Ed.), Butterworth, Stoneham, MA, 1984. 

Several studies have shown that the concentrations of many organic pollutants in fog water are much higher than would be expected from the compound s equilibrium air/ water partition constant (see Chapter 6), Kiaw (= gaseous concentration of compound i in the air/dissolved concentration of compound i in pure bulk water). In order to describe the observed enrichment of compounds in fog water, an enrichment factor EF can be defined (see Goss, 1994 and references cited therein) ... 

Fog (water and particulates) (CDDs) Collection of sample on Teflon screen collector extraction with CH2CI2 solvent evaporation and redissolution in hexane clean-up on silica gel column, HRGC/HRMS (MIM) No data No data Czuczwa et al. 1989... 

Nitrite is usually present in the environment at a lower concentration than nitrate, but its higher molar absorptivity and photolysis quantum yield can make it a competitive photoreactant under environmental conditions [13]. Usual concentration values of nitrite are below 2 jiM in seawater [13], below 0.1 mM in surface waters [7] and around 0.1-0.5 xM in the atmospheric aqueous phase in unpolluted areas [9]. Nitrite concentration was, however, found to reach up to 75 xM in fog water from California s Central Valley, and nitrite photochemistry was shown to account for 50-100% ofhydroxyl formation upon irradiation of the collected water samples [14],... 

Nitrate and nitrite photochemistry might also play a role in atmospheric hydrometeors. Nitrite photolysis has been shown to account for the majority of hydroxyl photoformation in irradiated fog water from a polluted site [ 14]. In addition, the generation of mutagenic and carcinogenic compounds from amino acids and amines dissolved in fog water [147] is a process that can be linked with nitrite photochemistry [20,141]. Furthermore, the formation of atmospheric nitrophenols partially takes place in aqueous solution. Reactions in the aqueous phase can account for about 30% of the atmospheric sources of mononitrophenols and for the vast majority of the dinitrophenol ones [ 148], and irradiation of nitrate and nitrite can possibly play a role in the process (see Sect. 3.2). Mono- and dinitrophenols are toxic compounds, and their occurrence in rainwater is thought to be a contributory factor in forest decline [149-151]. 

Figure 5.13 illustrates the composition of a radiation fog. In this particular case, the effect of HCl (probably from a refuse incineration plant at a distance of 3 km) caused a lowering of pH in the fog water as far down as pH 1.94. 

Example 5.7. Dissolution of Aerosols in Fog Water The following aerosol concentrations are measured prior to fog formation... 

What concentrations result in fog water (liquid water content q = lO"" liter m ) when 80% of the aerosols become dissolved in the water droplets ... 

Such processes play an important role not only in surface waters but also in atmospheric water droplets. Both Fe and oxalate are present in cloud and fog water oxalate is an intermediate in the oxidation of atmospheric organic pollutants. Iron is introduced into the atmosphere from dust it is present in these mostly slightly acid water droplets as in dissolved or colloidal form as Fe(II) and Fe(III) (Behra and Sigg, 1990). H2O2 formed by reactions such as 19-21 can oxidize SO2 in the aqueous atmosphere (see Example 9.3) (Faust, 1994 Hoigne et al., 1994 Kotronarou and Sigg, 1993 Sedlak and Hoigne, 1993, 1994). 

Eckardt, F.D. Schemenauer, R.S. (1998) Fog water chemistry in the Namib Desert, Namibia. Atmospheric Environment 32, 2595-2599. 

Schemenauer, R.S. Cereceda, P. (1992) The quality of fog water collected for domestic and agricultural use in Chile. Journal of Applied Meteorology 31, 275-290.

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