Ammonia

Total Ammonia Nitrogen (mg/L) **

The toxicity of ammonia relates primarily to the un-ionized form (NH3). The concentration of un-ionized ammonia present in water increases with pH and temperature. The values below represent total ammonia-nitrogen concentrations (at various temperatures and pH levels) above which accompanying NH3 concentrations may be harmful to aquatic life.

Total Ammonia (NH3 + NH4+)

(maximum levels expressed as N at various pH/temperature conditions)

Toxicity of Ammonia under varying Temperature and pH Conditions
Water Temperature (°C) / pH
(pH units)

10°

15°

20°

25°

30°

6.50

2.06

1.97

1.81

1.81

1.22

0.85

0.60

6.75

2.06

1.97

1.81

1.81

1.22

0.85

0.61

7.00

2.06

1.97

1.81

1.81

1.22

0.85

0.61

7.25

2.06

1.97

1.81

1.81

1.23

0.86

0.61

7.50

2.06

1.97

1.81

1.81

1.23

0.87

0.62

7.75

1.89

1.81

1.73

1.64

1.15

0.81

0.58

8.00

1.26

1.18

1.13

1.09

0.76

0.54

0.39

8.25

0.72

0.67

0.64

0.62

0.44

0.32

0.23

8.50

0.40

0.39

0.37

0.37

0.26

0.19

0.15

8.75

0.23

0.22

0.21

0.22

0.16

0.12

0.09

9.00

0.13

0.13

0.13

0.13

0.11

0.08

0.06

** excerpt from the "Surface Water Quality Objectives", Water Quality Branch Saskatchewan Environment and Public Safety, November, 1988 (WQ 110)

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Page last modified: 05 August 2010

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