Acid rain cleaning

Acids, and to a lesser extent bases, are part of our conversations, advertisements, and concerns. Headlines and television screens inform and persuade us about acid reflux, acid rain, cleaning compounds, and antacids (Figure 11.1). As you work your way through this unit and learn about acids and bases, you will find yourself looking at their presence in the world around you with a new awareness. 

Even rain is not pure water. Reports from the U.S. Geological Survey show that it contains 2.3—4.6 ppm of soflds, or a yearly precipitation of 2.5—5 t/km. Recently (ca 1997), work conducted ia the United States and Europe has underscored the rather dangerous results of iacreased use of fossil fuels, where the SO and NO emissions that end up ia the rain lower its pH from 5.6 (slightly acidic) for uncontaminated rain, to acid rains. Such acid rain has serious effects on surface waters (1). About 40 x 10 t of SO and 25 x 10 t of NO were emitted ia the United States ia 1980. There are, however, encouragiag trends the 1970 Clean Air Act has led to a gradual reduction ia these emissions, bringing the SO emissions down from the previous levels cited by 10% by 1990, and the NO emissions down by 6%, with a consequent slight decrease ia rain acidity. A part of the Clean Air Act is also iatended to cap SO emissions from major poiat sources at 13.5 x 10 t (2). Between 1994 and 1995, total SO emissions ia the U.S. decreased remarkably by 13% and total NO emissions by 8%. 

Other Titles - The Clean Air Act Amendments of 1990 continue the federal acid rain research program and contain several provisions relating to research, development and air monitoring. They also contain provisions to provide additional unemployment benefits through the Job Training Partnership Act to workers laid off as a consequence of compliance with the Clean Air Act. The Act also contains provisions to improve visibility near National Parks and other parts of the country. Strict enforcement of the Clean Air Act Amendments is the driving force behind pollution abatement. Non-compliance is simply not an option, since there are both financial and criminal liabilities that outweigh any benefits derived from a business. 

The reduction of atmospheric concentrations of the sulfur and nitrogen oxides blamed for acid rain was a major issue in the debate that led to the 1990 Clean Ail-Act Amendments (CAAA). The final legislative action is one of the most complex and comprehensive pieces of environmental legislation ever written. 

Public concerns about air quality led to the passage of the Clean Air Act in 1970 to amendments to that act in 1977 and 1990. The 1990 amendments contained seven separate titles covering different regula-toiy programs and include requirements to install more advanced pollution control equipment and make other changes in industrial operations to reduce emissions of air pollutants. The 1990 amendments address sulfur dioxide emissions and acid rain deposition, nitrous oxide emissions, ground-level ozone, carbon monoxide emissions, particulate emissions, tail pipe emissions, evaporative emissions, reformulated gasoline, clean-fueled vehicles and fleets, hazardous air pollutants, solid waste incineration, and accidental chemical releases. 

The world as we know it could not function without acids and bases. These chemical compounds are used extensively, from the chemical laboratory to the manufacturing industry. They are necessary for the proper functioning of the human body and for the health of the environment, too. Acids taste sour, break down metals, and react with bases. Without acids, soft drinks, lemonade, and tomato sauce would not taste the same way. Bases taste bitter, feel slippery, and react with acids. Without bases, cakes would be hard and flat, and laundry detergent would not clean. Both acids and bases can change certain vegetable substances a variety of different colors, and they can burn through human skin if not handled properly. Without acids and bases, we would not have dynamite, some heart medications, and fertilizers. On the other hand, without acids, we would not have damaging acid rain. And... 

However, in contrast to the previous clean air statutes, the 1990 amendments contained extensive provisions for control of the accidental release of air toxics from storage or transportation (TPG, 1995) as well as the formation of acid rain. At the same time, the 1990 amendments provided new and added requirements for such original ideas as state implementation plans for attaimnent of the national ambient air quality standards and permitting requirements for the attaimnent and nonattainment areas. Title III now calls for a vastly expanded program to regulate hazardous air pollutants (HAPs) or air toxics. 

For these pollutants, the atmosphere has the ability to cleanse itself within hours especially when the effects of the pollutant are minimized by the natural constituents of the atmosphere. For example, the atmosphere might be considered to be cleaning as a result of rain. However, removal of some pollutants from the atmosphere (e.g., sulfates and nitrates) by rainfall results in acid rain that can cause serious environmental damage to ecosystems within the water and land systems. 

Acid deposition acid rain a form of pollution depletion in which pollutants, such as nitrogen oxides and sulfur oxides, are transferred from the atmosphere to soil or water often referred to as atmospheric self-cleaning. The pollutants usually arise from the use of fossil fuels. 

The detrimental effects of acid rain are a major reason why legislation such as the Clean Air Act places strict limitations on sulfur and nitrogen emissions. It is also a reason why low sulfur coal is preferred over high sulfur coal. To reduce sulfur dioxide emissions, industry also uses a technique call scrubbing. Industrial scrubbers employ a variety of physical and chemical processes to remove sulfur dioxide from emissions. Another technique used to combat acidification of lakes is to treat these systems with lime. The lime acts to neutralize the acid, but such techniques are usually costly and are only a temporary remedy for combating the problem. 

In recent years, much political and environmental attention has been paid to the idea of clean coal technology. Coal is a cheap and relatively available source of energy, but the smoke from its burning creates enormous amounts of air pollution, as well as acid rain. 

Implementation of the Acid Rain Program under the 1990 Clean Air Act Amendments will confer significant benefits on the nation, By reducing SO ... 

Title IV of the Clean Air Act Amendments of 1990 calls for a 10 million ton reduction in annual emissions of sulfur dioxide (S02) in the United Stales by the year 2010, which represents an approximately 40 percent reduction in anthropogenic emissions from 1980 levels, Implementation of Title IV is referred to as the Acid Rain Program the primary motivation for this section of the Clean Air Act Amendments is to reduce acid precipitation and dry deposition. To achieve these reductions, the law requires a two-phase tightening of the restrictions placed on fossil-fuel-lired power plants. 

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