שאלה | The removal efficiency of organic matter in an SAT pond, at 25 cm depth, increases to a 40% peak approximately 20 h from the initiation of the flooding cycle and then begins to decrease. What is the most plausible reason for this observation?

The removal efficiency of organic matter in an SAT pond, at 25 cm depth, increases to a 40% peak approximately 20 h from the initiation of the flooding cycle and then begins to decrease. What is the most plausible reason for this observation?

		The pond has dried out, and there is not sufficient moisture for biodegradation.
		The biodegrading microbiota has died due to a poisonous substance in the water.
		Most of the oxygen was consumed, and therefore, the efficiency of the biodegradation is reduced.
		There is a lack of sunlight.