Importance of Clean Freshwater
With all of the demands humans place on the hydrosphere, as well as climate changes which have led to droughts, the amount of available freshwater is decreasing. In addition, much of the available freshwater is being contaminated with harmful elements such as sulfuric acid, fertilizer, and gasoline. This happens as freshwater circulates through the hydrologic cycle. As precipitation passes through the atmosphere and flows over roads, agricultural fields, and other human-made objects, it picks up contaminants that often make it unusable. In a sense, precipitation "washes" the dirt and grime (contaminants) from the air and Earth's surfaces, just like the water washes the dirt off of you when you bathe. These contaminants are then carried to the streams, rivers, and eventually into the groundwater, lakes, and oceans of the world. Water quality may also be affected by natural causes such as volcanic eruptions.
The importance of clean water, coupled with its scarcity due to over-use, climate, and pollution, has resulted in increased concerns about water quality and quantity. These concerns have led to war between nations such as Namibia and Botswana. The concerns have even influenced US legislation.
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