Question

Dissolved ammonia is a common contaminant in drinking water, streams, and rivers. The dissolved form can cause an unpleasant taste in the water and is toxic to many aquatic life forms. Gaseous ammonia (NH3) has an unpleasant odor that has been described as similar to baby diapers or window cleaner.

b. Fish are very sensitive to un-ionized ammonia (NH3) and concentrations as low as I .0 mg/L can be toxic. If you took a sample of water downstream of a wastewater treatment plant and measured a pH of 8.3, and a total dissolved ammonia (NH3 + NH4) concentration in the water of 0.8 x 10^-3 M, would you expect a toxic effect on the fish in the river? Support your answer with calculations.

c. An average person can detect the odor of ammonia gas at a concentration of about 5 ppm (by pressure or volume) in the air. At what dissolved ammonia (NH3) concentration (in mg/L) would you expect an average person to notice a funny smell from the water? Assume you are at sea level and the temperature is 25 C.

f. What if you were analyzing potential toxicity of ammonia in the Choqueyapu River, which flows through La Paz, Bolivia at 3,650 m above sea level. The total air pressure at this altitude is 64 kPa. At what dissolved ammonia concentration (in mol/L) would you expect an average person to notice an odor?

Answer 1