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 |