Which statement is true about the lagoon sample collected at 2:15 PM?

Which statement is true about the lagoon sample collected at 2:15 PM?

• A. DO was 20 mg/L
• B. pH was 7.0
• C. Lagoon color was brown
• D. Aerators were running

Answer: (A)

Dissolved oxygen levels in lagoons indicate how much oxygen is available for aerobic microbial processes and are strongly influenced by daylight-driven photosynthesis and aeration. At 2:15 PM, when sunlight is abundant, algae and other photosynthesizers can boost oxygen production, and active mixing from aerators can carry that oxygen throughout the lagoon. A reading of 20 mg/L for dissolved oxygen reflects this daytime high-oxygen condition and is consistent with a well-oxygenated lagoon sample collected in the afternoon, making it the statement that matches the data provided for that time. The other aspects—pH around 7.0, lagoon color being brown, or whether aerators were running—would require specific data not given in the sample, so they aren’t the statements we can confirm from the information provided.

Dissolved oxygen levels in lagoons indicate how much oxygen is available for aerobic microbial processes and are strongly influenced by daylight-driven photosynthesis and aeration. At 2:15 PM, when sunlight is abundant, algae and other photosynthesizers can boost oxygen production, and active mixing from aerators can carry that oxygen throughout the lagoon. A reading of 20 mg/L for dissolved oxygen reflects this daytime high-oxygen condition and is consistent with a well-oxygenated lagoon sample collected in the afternoon, making it the statement that matches the data provided for that time.

The other aspects—pH around 7.0, lagoon color being brown, or whether aerators were running—would require specific data not given in the sample, so they aren’t the statements we can confirm from the information provided.