0
50
100
150
200
250
300
350
400
0
200
400
600
800
1000
1200
1400
1600
1800
Aluminum chronic
Cadmium acute
Cadmium chronic
Chromium acute
Chromium chronic
Copper acute
Copper chronic
Lead acute
Lead chronic
Nickel acute
Nickel chronic
Silver acute
Zinc acute
Zinc chronic
Hardness dependent criteria
Hardness (mg/L)
Criterion (ug/L)