I

II

III

IV

V

TN

R < 5

5 < R < 10

10 < R < 15

15 < R < 20

R > 20

TP

R < 0.5

0.5 < R < 1

1 < R < 2

2 < R < 3.5

R > 3.5

COD

R < 40

40 < R < 70

70 < R < 100

100 < R < 140

R > 140

等标指数

R < 5

5 < R < 15

15 < R < 30

30 < R < 45

R > 45

硝态氮

R < 2

2 < R < 5

2 < R < 20

20 < R < 30

R > 30