Sulfur oxides fossil fuels

The primary cause of acid rain is industrial and automotive pollution. Each year in industrialized countries, large power plants and smelters that burn sulfur-containing fossil fuels pour millions of tons of sulfur dioxide (S02) gas into the atmosphere, where some is oxidized by air to produce sulfur trioxide (S03). Sulfur oxides then dis-l solve in rain to form dilute sulfurous acid and sulfuric acid ... 

Sulfur dioxide from the combustion of sulfur-containing fossil fuels (e.g., diesel oil and coal) is oxidized in the atmosphere to form sulfur trioxide that reacts with water to form sulfuric acid. 

Sulfur dioxide (SO2)—A colorless gas formed when sulfur oxidizes, often as a result of burning trace amounts of sulfur in fossil fuels. 

Sulfur and nitrogen oxides Fossil fuel combustion... 

Biodesulfurization is a process that removes sulfur from fossil fuels using a series of enzyme-catalyzed reactions.Biodesulfurization is another alternative processing method that has some similarity to the above-mentioned oxidative desulfurization, in that both methods oxidize sulfur atoms in the sulfur-containing compounds. Certain microbial biocatalysts have been identified that can biotransform sulfur compounds found in fuels, including ones that selectively remove sulfur from dibenzothiophene-type heterocyclic compounds. " Biocatalytic sulfur removal from fuels may have applicability for producing low sulfur gasoline and diesel fuels. 

Municipal incinerators are often targeted as a primary cause of acid rain. In fact, power plants burning fossil fuels, which produce sulfur dioxide and nitrogen oxide, are actually the leading cause of acid rain, along with automotive exhaust (176,177). In Europe and Japan, studies show that only about 0.02% of all acid rain can be traced to incineration of PVC (178). 

Acid deposition occurs when sulfur dioxide and nitrogen oxide emissions are transformed in the atmosphere and return to the earth in rain, fog or snow. Approximately 20 million tons of SOj are emitted annually in the United States, mostly from the burning of fossil fuels by electric utilities. Acid rain damages lakes, harms forests and buildings, contributes to reduced visibility, and is suspected of damaging health. 

The increasing number of atomic reactors used for power generation has been questioned from several environmental points of view. A modern atomic plant, as shown in Fig. 28-3, appears to be relatively pollution free compared to the more familiar fossil fuel-fired plant, which emits carbon monoxide and carbon dioxide, oxides of nitrogen and sulfur, hydrocarbons, and fly ash. However, waste and spent-fuel disposal problems may offset the apparent advantages. These problems (along with steam generator leaks) caused the plant shown in Fig. 28-3 to close permanently in 199T. 

Burning fossil fuels can release air pollutants such as carbon dioxide, sulfur oxides, nitrogen oxides, ozone, and particulate matter. Sulfur and nitrogen oxides contribute to acid rain ozone is a component of urban smog, and particulate matter affects respiratory health. In fact, several studies have documented a disturbing correlation between suspended particulate levels and human mortality. It is estimated that air pollution may help cause 500,000 premature deaths and millions of new respiratory illnesses each year. 

Power plant emissions result from the comhustion of fossil fuels such as coal, gas, and oil. These emissions include sulfur dioxide (SO,), nitrogen oxides (NO.,), particulate matter, and hazardous air pollutants, all of which are subject to environmental regulations. Another emission is carbon dioxide (CO,), suspected of being responsible for global warming. 

The remaining. SO percent or less ot supply must have an average emission rate below the system average for fossil-fuel-emitted sulfur dioxide, nitrogen oxide, and carbon dioxide. 

Table 19-1 demonstrates that with the exception of water vapor, all of these cycles have been severely perturbed by human activity. Of course, all of these cycles are also linked in many ways. For example, the combustion of fossil fuel has increased the fluxes of carbon, sulfur, and nitrogen oxides to the atmosphere. Denitrification, the production of N2O, is linked with the production of CO2 during respiration and decay. And of course, other important cycles are involved which are not depicted here. Look back at Fig. 17-8, which sums up the climate forcings by the key agents. 

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