Acid rain composition

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. 

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. 

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. 

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. 

Most composite propellants in wide use today use ammonium perchlorate as the oxidizer component. While such propellants benefit from high specific impulse and a lower vulnerability than double-base propellants based on nitroglycerine, they have a significant environmental impact, the exhaust fumes being rich in corrosive hydrogen chloride leading to acid rain after the launch of missiles/rockets. 

The term acid rain was hrst coined in 1872 by the English chemist Robert Angus Smith (1817-84). Smith studied the composition of rain in the region around Manchester, England, and observed... 

Although AP is the most widely used oxidizer for composite propellants, it is not environmentally friendly, and results in acid rain and the hazard of ozone depletion. Also its exhaust signature leads to problems of detection and tracking... 

Kettles, I.M. and Shilts, W.W. (1994) Composition of glacial sediments in Canadian shield terrane, southeastern Ontario and southwestern Quebec applications to acid rain research and mineral exploration. Geological Survey of Canada Bulletin, 463, Report, 58 pp. 

An effect of acid rain in streams is to increase the amount of filamentous algae. It is doubtful, however, that it is a case of direct action resulting from the composition of the water, rather than being due to a decrease in herbivorous animals. As acidification increases, the number of animal species in the water decreases. There is a sharp reduction in herbivorous insects, while in the case of carnivorous insects no such dramatic result can be seen. 

Shown in Fig. 9.9 are water-composition ranges for some humid-climate streams (in New Jersey), a dilute, freshwater lake (Lake Huron) and lake-bottom muds from the Great Lakes (Sutherland 1970), and deep-soil moisture from Pennsylvania (Sears 1976 Sears and Langmuir 1982). Lake Huron and the Delaware River are dilute, humid-climate waters. They both plot near the kaolinite-gibbsite boundary. Their composition can be described as water dominated. In other words, their chemistries are controlled chiefly by dilution with fresh rainfall and runoff, not by reactions with geological materials. In a study of acid rain (water-dominated) control of soil moisture and ground-water chemistry of a sandy aquifer in Denmark, Hansen and Postma (1995) found that pore waters were close to equilibrium with gibbsite and supersaturated with kaolinite (Fig. 9.9). Precipitation pH = 4.34 at the site, and log([K+]/lH+]) = -0.95. 

In this paper, we describe an onsite weathering experiment designed to identify acid-rain increased dissolution of carbonate rock. This experiment is based on the measurement of the change in rainfall-runoff composition from the interaction of a rock surface with incident acid rain 2. The experiment involves conducting long-term exposures of two commercially and culturally important calcium carbonate dimension stones (i.e., Indiana Limestone (commercial name for Salem Limestone) and Vermont Marble (commercial name for Shelburne Marble)) (3-5). This technique appears to give a direct measurement of the chemical dissolution of carbonate rock from the combined reactions of wet and dry deposition. Preliminary results from the initial months of onsite operation are presented to illustrate the technique. 

Carbonate-rock acid-rain reaction stiochiometry is best examined using a mathematical model of the ionic species present in a dilute carbonate solution. Appropriate models have been recently developed and are used with an electronic digital computer. Although a discussion of the application of mineral-reaction modeling is outside the scope of this paper, several recent publications explain its use in the study of carbonate-mineral reactions in aqueous solution (9-11). A reaction model, such as PHREEQE (11), the model used in this study, incorporates changes in gas-solution and solution-solid equilibria, as well as ionic equilibria in solution, in arriving at a final equilibrium-solution composition (. ... 

TABLE 1 Composition of Synthetic Acid Rain Samples... 

This booklet discusses the composition and major causes of acid rain. 

The models therefore reflect our level of knowledge of die soil solution and its interaction with soil solids. Since these models have the potential to predict the composition of natural waters (groundwater, lakes and streams, oceans as well as the soil solution), soil fertility, the effects of fertilizers and soil amendments, the effects of acid rain, and the attenuation and release of pollutants in soils, this important area of research should be actively pursued. The accuracy of the models, however, is still based on our understanding of the soil s chemistry and cannot be more accurate than that. 

The effects of acid rain can be devastating. The pH of lakes and streams is lowered, although the composition of the bedrock is significant, and in some cases provides a natural buffering effect. A second effect is that acid rain penetrating the bedrock can react with aluminosilicate minerals, or can... 

The chemical composition of acid rain in China is generally different from that in Europe, with a lower pH value and a higher sulfate, calcium and ammonium... 

Sanhueza E., Arias M. C., Donoso L., Graterol N., Hermosos M., Marti L, Romero 1., Rondon A. and Santana M., 1992. Chemical composition of acid rains in the Venezuelan savannah region. Tellus, 44B 54-62. 

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