Class

Alkaline

Neutral

Weak acid

Acid

Strong acid

pH

>7.5

6.5 - 7.5

5.5 - 6.5

4.5 - 5.5

≤4.5

Proportion (%)

1.26

9.73

28.92

60.06

0.04

Area (km2)

514

3973

11814

24529

15