Chemical Characteristics Indicators
pH
pH is a term used to indicate the alkalinity or acidity of a substance as ranked on a scale from 0 to 14. A pH of 7 is neutral. The technical definition of pH is that it is a measure of the activity of the hydrogen ion (H+) and is reported as the reciprocal of the logarithm of the hydrogen ion activity. Therefore, water with a pH of 7 has 10−7 moles per litre of hydrogen ions; whereas a pH of 6 is 10−6 moles per litre. Most organisms have adapted to life in water of a specific pH and may die if it changes even slightly. The toxicity stage of ammonia to fish, for instance, varies tremendously inside a small range of pH values. Acid rain containing nitric and sulphuric acids can sharply lower the pH of a stream as the rain runs quickly off streets and roofs into creeks. Acidic water could cause heavy metals like as copper and aluminum to be released within the water. Copper from worn automobile brake pads is often present in runoff. Rapid growing algae remove carbon dioxide from the water during photosynthesis that could result in a significant increase in pH levels.