While the Amazon river is the world's second-longest--behind the Nile--it is the largest in terms of volume, according to National Geographic's website. The Amazon river contains 20 percent of the fresh water on Earth and its freshwater systems contain minerals that are important to fertilizing land in the rainforest. Water pollution is worsening in the Amazon as a result of extensive logging in the rainforest. Areas that were once thick with trees have been converted into open plains, resulting in forest flooding. Gold mining is leading to mercury pollution and dams that are being built in the river basin may alter the flow of water in the river.
The World Wildlife Fund, or WWF, notes on its website that deforestation is a primary threat in the Amazon and one that is a major contributor to global warming. By the year 2030, more than half of the forests in the Amazon could be gone. This loss would result in the release of billions of tons of carbon into the Earth's atmosphere.
Save the Rainforest notes that numerous trees have been cleared--often by the so-called "slash-and-burn" method--in order to build hydroelectric dams. However, the industrial projects powered by these dams pollute the surrounding area. Dams also trap silt that drifts downstream and damages delicate ecosystems. In addition, the shift from small-scale to large-scale agriculture in places such as the Amazon also contributes to pollution through the use of fertilizers and pesticides that are harmful to the soil and water.
The U.S. House of Representatives' Select Committee on Energy Independence and Global Warming lists the Amazon rainforest as a global impact zone. As the area continues to lose soil and plant carbon, larger amounts of carbon dioxide and methane gases are released into the atmosphere--this pollution contributes to global warming, according to the committee's website. The shrinking rainforest could result in the Amazon shifting from a carbon bank that keeps the element out of the atmosphere, to a source of carbon in the atmosphere by the year 2050.
