FIGURE 6–11 Acid Rain Acid rain results from the chemical transformation of nitrogen and sulfur products that come from human activities. These reactions can cause damage to stone statues and plant life.

▸ Acid Rain When we burn fossil fuels in our factories and homes, we release nitrogen and sulfur compounds. When those compounds combine with water vapor in the air, they form nitric and sulfuric acids. These airborne acids can drift for many kilometers before they fall as acid rain. Acidic water vapor can also affect ecosystems as fog or snow. In some areas, acid rain kills plants by damaging their leaves and changing the chemistry of soils and surface water. Examples of its effects are shown in Figure 6–11. Acid precipitation also can dissolve and release mercury and other toxic elements from soil, freeing those elements to enter other parts of the biosphere.

In Your Notebook Create a flowchart that shows the steps in acid rain formation.

▸ Greenhouse Gases Burning fossil fuels and forests releases stored carbon into the atmosphere as carbon dioxide, a greenhouse gas. Agricultural practices from raising cattle to farming rice release methane, another greenhouse gas. Although some greenhouse gases are necessary, when excess greenhouse gases accumulate in the atmosphere, they contribute to global warming and climate change.

▸ Particulates Particulates are microscopic particles of ash and dust released by certain industrial processes and certain kinds of diesel engines. Very small particulates can pass through the nose and mouth and enter the lungs, where they can cause serious health problems.

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