south river monitoring

Why is pH important?
This year’s new indicator is pH. Measuring pH and alkalinity in the South River and throughout the South River watershed are extremely important to understanding its overall health. Since the pH of water is critical to the survival of most aquatic plants and animals and alkalinity is a measurement of the water’s capacity to neutralize acids, monitoring pH is vitally important. Substances with a pH of less than 7 are acidic, and those with a pH greater than 7 are basic.

What causes pH changes?
Biological activity can significantly alter pH in the South River. Through a process called photosynthesis, plants remove carbon dioxide (CO2) from the water and expel oxygen (O2). Since CO2 becomes carbonic acid when it dissolves in water, the removal of CO2 results in a higher pH, and the water becomes more alkaline, or basic. When algae naturally begin to increase in estuaries during the spring, pH levels tend to rise. An overabundance of algae (called an algal bloom) may cause pH levels in the river to rise significantly, and this can be lethal to aquatic animals

Where has this been occurring?
The increase in pH peaks shortly after the chlorophyll and/or blue-green algae blooms.

When does this occur?
These increases in pH have generally been occurring in the late spring through the summer, however due to the high nutrient concentrations and climatic events, blooms have also been occurring in the fall and early winter. The impact is that aquatic animals which can only live in a narrow pH range are stressed or killed by the fluctuations.