Unionized ammonia nitrogen is lethal at which pair of mg/L values?

Unionized ammonia nitrogen is lethal at which pair of mg/L values?

• A. 2,5
• B. 5,0
• C. 0.5, 0.1
• D. 0.1, 0.5

Answer: (C)

Unionized ammonia (NH3) is the toxic form, and its proportion in water rises with higher pH and warmer temperatures. Because of that, the lethal concentration for fish is kept in the sub‑mg/L range and changes with environmental conditions. The two numbers 0.5 mg/L and 0.1 mg/L reflect this condition-dependent toxicity: about 0.1 mg/L NH3-N can be lethal under cooler or lower‑pH conditions, while around 0.5 mg/L NH3-N becomes lethal under warmer or higher‑pH conditions. That range best matches how NH3-N toxicity behaves in real aquaculture scenarios. The other options propose much higher values that don’t align with the typically observed, highly toxic nature of unionized ammonia at common water temperatures and pH levels.

Unionized ammonia (NH3) is the toxic form, and its proportion in water rises with higher pH and warmer temperatures. Because of that, the lethal concentration for fish is kept in the sub‑mg/L range and changes with environmental conditions. The two numbers 0.5 mg/L and 0.1 mg/L reflect this condition-dependent toxicity: about 0.1 mg/L NH3-N can be lethal under cooler or lower‑pH conditions, while around 0.5 mg/L NH3-N becomes lethal under warmer or higher‑pH conditions. That range best matches how NH3-N toxicity behaves in real aquaculture scenarios. The other options propose much higher values that don’t align with the typically observed, highly toxic nature of unionized ammonia at common water temperatures and pH levels.