Why does the BOD level in a stagnant water rises?
BOD = Biochemical Oxygen Demand. This is a measure of the amount of oxygen that would be required to oxidize and/or metabolize all of the organic and chemical substances in that particular sample of water. It was developed as a measure of the strength of sewage that was discharged to streams. Sewage (or any other water with a high BOD) will cause the oxygen in receiving waters to be used up, or depleted, making it impossible for any organisms requiring oxygen to live there. This includes almost all aquatic organisms, such as fish, aquatic plant life, etc. The higher the BOD, the more oxygen will be used, and the greater the impact. The BOD level in stagnant water will rise largely because the stagnant water does not contain sufficient oxygen for any BOD present to be oxidixed or metabolized. Therefore, the substances that cause high BOD will tend to accumulate and increase in concentration. Stagnant water tends to have less oxygen than flowing water because there is less chance for mix
