Discuss the positive and negative impact of acid rain on humans and the environment.

Why acid rain is harmful to humans and the environment.

1) Acid rain can contribute to respiratory diseases and exacerbate existing medical conditions. For example, the nitrogen oxide in acid rain leads to the creation of ground-level ozone, which in turn can contribute to respiratory diseases such as pneumonia and bronchitis.

2) Acid rain can increase levels of aluminum in the soil, which prevents trees from taking up adequate water. What is even more troubling is that the higher levels of aluminum can eventually end up in streams and rivers. This in turn can prove fatal to aquatic as well as forest wild-life.

3) Acid rain has contributed to lower pH levels in streams and rivers across the United States, especially in the Northeast region. Most bodies of water have pH levels of about 6.5. Lower pH levels mean that the water is more acidic rather than alkaline. The Environmental Protection Agency recommends that pH levels of water be between 6.5 to 8.5 for drinking purposes. Bodies of water with lower pH levels may have higher iron and sulfur deposits, which in turn can prove harmful to the health of wildlife and humans. Sensitive species of wildlife may experience higher than normal mortality rates if the pH levels of water move away from the optimum range.

The advantages of acid rain.

It has recently come to the attention of the science community that acid rain may have a positive impact on humans and the environment.

As a rule, carbon dioxide and methane contribute significantly to what is considered global warming. However, the sulfur dioxide in acid rain suppresses some portion of methane production in the atmosphere. Methane results from bacteria breaking down organic compounds, and the sulfur in acid rain appears to suppress up to 30 or 40% of methane production in wetlands areas. For example, tests by NASA's Goddard Space Flight Center show that the sulfur in acid rain will continue to suppress methane production until at least 2030.

Other studies have shown that a rise in temperature, along with greater concentrations of nitrogen in the atmosphere, can contribute to higher growth in forests. For example, the nitrogen in acid rain allows the trees to store more carbon. This process is called carbon sequestration and is quite beneficial: higher carbon reserves allow a tree to produce the optimum level of sugars and carbohydrates necessary for growth. The National Institute for Climatic Change Research's Midwestern Regional Center has performed studies concluding that acid rain can contribute to forest growth.

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