Rain, composition

Direct evidence of metal dissolution is given by the analysis of rain composition [35]. Fe and Cu present in clouds originate in crustal and combustion aerosols. Their concentrations in rural air are in the ranges 0.1-100 and 0.001-0.1 pgnr3, respectively, while typical concentrations of 0.1-20 p,M for Fe and 0.001-0.3 p,M for Cu are found in cloud water [1],... 

Cadle and Groblicki (J[0) determined the composition of dew deposited naturally on glass. Teflon, and plastic surfaces in Warren, MI. Dew composition was compared to wet and dry deposition obtained the previous year at the same site. In this paper, the comparison of dew and rain composition is updated and the results of a new study of the composition of artificially-generated dew are reported. Deposition velocities to the dew of SO2, HNO and K are also presented. 

Using a computer model developed from solution equilibrium techniques discussed by Lindsay [4], analytical data were used to calculate the activities and molarities of 29 species in solutions recovered from the coquina columns. A typical computer print-out shown in Figure 1 lists the solution species as well as their activities and molarities. The resulting data were used to interpret the effects of initial pH, ionic strength, acid rain composition and column length on degradation of coquina. 

Remote Areas Table 20.3 shows rain composition in five remote areas in 1980-81 based on the study of Galloway et al. (1982). 

TABLE 20.3 Mean Rain Composition in Remote Areas of the World Based on 1980-1981 Data... 

Figure 3 is a plot of Cl versus Na" for all daily rain events obtained in this study. As expected, a linear dependence is visible it is indicative of the contribution of sea salt to rain composition. The Cl /Na ratio in Haifa is not different from the ratio of 1.16 (concentrations are in eq/1) reported for other coastal sites (Lebowitz and de Pena, 1985). However, the values obtained in Israel are some of the highest ever... 

Quantitative studies of solid-state organic reactions were performed by Glazman (267. 268). Equal amounts of acetic anhydride and 2-aminothiazole (grain diameter 0.15 mm) were mixed for 20 rain, and the mixture was heated in a glycerol bath at 0.5°C per minute. Heating curves showed that the reaction starts in the solid phase the use of an eutectic composition of organic reactants increases the yields. 

Acid deposition refers to the transport of acid constituents from the atmosphere to the earth s surface. This process includes dry deposition of SO2, NO2, HNO3, and particulate sulfate matter and wet deposition ("acid rain") to surfaces. This process is widespread and alters distribution of plant and aquatic species, soil composition, pH of water, and nutrient content, depending on the circumstances. 

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

The composition of the earth s atmosphere differs from day to day, from altitude to altitude, and from place to place. The largest variation is in the concentration of water vapor. Water evaporates continually from the hydrosphere, from the soil, from leaves, from clothes drying, etc. At intervals, parts of the atmosphere become chilled until the dew point or frost point is reached and then any vapor in excess of the saturation amount is precipitated as rain or snow. 

Table II summarizes analytical data for dissolved inorganic matter in a number of natural water sources (J3, 9, J 9, 20, 21). Because of the interaction of rainwater with soil and surface minerals, waters in lakes, rivers and shallow wells (<50m) are quite different and vary considerably from one location to another. Nevertheless, the table gives a useful picture of how the composition of natural water changes in the sequence rain ->- surface water deep bedrock water in a granitic environment. Changes with depth may be considerable as illustrated by the Stripa mine studies (22) and other recent surveys (23). Typical changes are an increase in pH and decrease in total carbonate (coupled), a decrease in 02 and Eh (coupled), and an increase in dissolved inorganic constituents. The total salt concentration can vary by a factor of 10-100 with depth in the same borehole as a consequence of the presence of strata with relict sea water. Pockets with such water seem to be common in Scandinavian granite at >100 m depth.

Rain in equilibrium with atmospheric C02, but uncontaminated by industrial emissions, should have a pH of 5.7. However, atmospheric pollution from burning fossil fuels has resulted in acid rain of pH as low as 3.5 (24). If this condition continues for a long time, it may lead to a change in groundwater composition, which may considerably change the migration of plutonium in nature. 

The detrital rain of carbon-containing particles can be divided into two groups the hard parts comprising calcite and aragonite and the soft tissue containing organic carbon. The composition of the soft tissue shows surprising... 

The evaporite source is characterized by covariation of sulfate (from gypsum) and chloride (from halite). That elements can be recycled from the ocean to land by movement of saltbearing aerosols (so-called "cyclic salts") has confused the interpretation of river flux data somewhat. While this cycling generally follows the ratio of salts in the sea, the S/Cl ratio is an exception. Taking the S/Cl ratio of the cyclic component to be 2 (based on compositional data for marine rains) and assuming that all chloride in rivers is cyclic, an upper limit for the cyclic influence can be calculated. 

FIGURE 23 Hydration layer in obsidian. When obsidian is broken into two or more pieces, new surfaces are created. As a new surface is exposed to the environment, water (from atmospheric humidity, rain, or the ground) penetrates the surface gradually, the water diffuses into the bulk and forms hydrated obsidian, that is, obsidian containing water. With time, the thickness of the hydration layer, as such a layer is known, gradually increases the rate of increase is affected by such factors as the vapor pressure of the water in the atmosphere, the environmental temperature, and the composition of the surrounding environment as well as of the obsidian. If the hydration layer reaches a thickness of 0.5 microns or more, it becomes discernible under a microscope, the thickness can be measured, and the age of the surface calculated. The microphotograph shows an hydration layer on obsidian. 

Water vapor enriched in oxygen-16 is transported by wind in the atmosphere from the sea to land. When the water vapor condenses and precipitates as rain, snow, or hail, the water becomes rich in oxygen-16. Eventually the oxygen-16 rich water is incorporated into rivers, lakes, glaciers, and polar ice, which are, therefore, also rich in oxygen-16. Thus the isotopic composition of groundwater and the water of rivers, lakes, and glaciers is not the same as in seas and oceans. 

Acid rain harms the environment in a number of ways it dissolves many rocks and metals, alters the composition of soils, groundwaters, and lakes, and alters the environmental conditions of living organisms. Acid rain is also particularly harmful to ancient objects and structures, as it plays an important role in their deterioration and sometimes total destruction. Unprotected limestone, marble, and sandstone, all of them widely used in ancient times for building and making statuary, are disintegrated by acid rain, which... 

Informed debate and decisions on such important matters as the depletion of the ozone layer, acid rain and the quality of waterways all depend on the data provided by analytical chemists. Forensic evidence also often depends on chemical measurements. National and international trade are critically dependent on analytical results. Chemical composition is often the basis for the definition of the nature of goods and tariff classification. In all of these areas not only is it important to get the right answer but it is essential that the user of the results is confident and assured that the data are truly representative of the sample and that the results are defendable, traceable and mutually acceptable by all laboratories. 

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