At left: Cub Creek. Photo by Chuck Sutherland.
pH is a measure of the relative amount of hydrogen and hydroxide ions in water. The values for pH range from 0 to 14 on a log scale, meaning that a difference of 1 is actually a monumental difference. Values from 0 to 7 are considered acidic, while those greater than 7 are alkaline. Naturally, the pH of surface water can vary from 6.5 to 8 without any repercussions to aquatic ecosystems.
The pH of surface or groundwater can change for a variety of reasons, both natural and anthropogenic. Organisms that release CO 2 when they respirate can contribute to acidification of the water, as CO 2 and water combine to form an acid. However, the more common reasons are acid runoff from abandoned mine sites or acid rain from nitrates and sulfates in the atmosphere. The type of bedrock present can greatly impact the pH of surface water in an area. For instance, if limestone is the most common rock in a region, such as in Tennessee, waters are more prone to be neutral or alkaline, as limestone is basic. Some other types of rocks can further decrease the pH of acidic liquids.
A low pH is a more common cause of issues than a high pH, although both occur. Acidic conditions can prevent fish from reproducing, or kill adult fish themselves. Additionally, metals are more toxic when conditions are acidic, and sediments are more prone to release toxic materials. In alkaline conditions, ammonia is more dangerous to organisms.How To Help (And Who Can Help You)1. Contact the EPA.2. Allow for natural growth near waterways.3. Limit impervious surfaces.4. Plant a rain garden.5. Plan for a better future.6. Contact your representatives.7. Support your local watershed stewards.8. Spread the word.Ready To Make A Difference?Pledge to do one or more of these mitigation activities!