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The Effects of Alkalinity in Water on the Environment's Health

The pH scale measures whether a substance is an acid or a base. For bodies of water like streams, ponds and lakes, it is important to keep the pH reading as close to neutral as possible. Alkalinity is the capacity of a body of water to neutralize acids. This buffering effect plays a role in the health of bodies of water as they affect the environment.

Keeping pH of Water Stable
- The scale for pH ranges from 0 to 14 with 7 being neutral. A reading below 7 is an acid and above 7 is a base. Normal rain measures 5 to 6 and does not have an acidic effect on bodies of water. Typical stream water reads 5 to 7. Problems arise when the water becomes too acidic, and the alkalinity in water plays a role in regulating the level.
Counteracting Acid Rain
- Acid rain results from sulfur dioxide and nitrogen dioxide in the atmosphere. Power plants that use coal and motor vehicle exhaust produce the most of the two pollutants. Rain becomes polluted with these materials, and the sulfur and nitrogen dioxide become part of the water system as the rain enters streams, lakes and ponds. When acid rain lowers the pH factor to 4, fish reproduction is affected. Fish begin to die at 3, and acid rain can lower water to 0. High alkalinity of water can counteract acid rain by removing the acid and keeping the pH level in the normal range.
More Nutrients
- High alkalinity is the result of bicarbonate and carbonate materials added to water. These buffering materials become part of the composition for streams as they flow through limestone or soil with high levels of carbonate. Conversely, if the streams encounter igneous rock or soil without carbonates, then the alkalinity will be low. High alkalinity means more nutrients and that promotes aquatic life in the stream.
Poor Plant Nutrition
- High alkalinity in water exerts a negative effect on plant nutrition. Water for plant irrigation that contains high levels of carbonates damages plants. The effect is similar to watering plants with diluted limestone. The amount of water must be regulated, especially if the pH level is too high. High pH and high alkalinity is a bad combination for irrigation.

Nature