Science Olympiad Green Generation Practice Test

An increase in the decomposition of organic matter leads to a greater demand for oxygen in aquatic environments. When organic matter decomposes, bacteria and other microorganisms break it down, consuming oxygen in the process. This biological activity increases the biochemical oxygen demand (BOD), which is the amount of oxygen required by these microorganisms to decompose the organic material.

As decomposition intensifies, the increased consumption of oxygen can significantly lower the levels of dissolved oxygen in the water. Lower dissolved oxygen readings can result in stress or mortality for aquatic organisms, such as fish and invertebrates, that depend on adequate oxygen levels for survival. Therefore, it is expected that an increase in the decomposition of organic matter will lead to a decrease in dissolved oxygen readings.