What is pH?

pH stands for the "power of Hydrogen" and measures the concentration of hydrogen ions in a solution, such as water. What is a hydrogen "ion?"  It is an atom of hydrogen that has lost its electron. In water, hydrogen automatically gives up its electron to form ions.

pH varies over an enormous range of values. Thus, it has to be measured on a scale that is different from other measurement scales.  A solution with a pH=0 has 10 times more hydrogen ions than a solution with a pH=1 and 100 times more hydrogen ions than a solution with a pH=100.  This "logarithmic" type of scale is commonly used in chemistry and physics to specify the value of numbers that have an extreme range of values. 
 

What affects pH?

pH or the concentration of hydrogen ions in water is largely determined by the environment surrounding a lake, river, or stream.  Changes in pH can be the result of natural phenomena or man-made events.  A change in pH can disrupt the life cycles of all organisms (animals and plants) and lead to their deaths if the change is hydrogen ion concentration is too extreme.

How important is pH?

Is water quality affected by pH?  What happens to organisms when pH changes?  What causes a change in pH?  In this unit, you will discover answers to these questions.