Table 1.
Estimated area (millions of km2) of each continent (percentage in parentheses) predicted to have acceptable periphyton growth and N-limitation (catchment type 1), undesirable periphyton growth with N-limitation (catchment type 2), acceptable periphyton growth and P-limitation (catchment type 3) and undesirable periphyton growth with P-limitation (catchment type 4).
| Continent | Type 1 | Type 2 | Type 3 | Type 4 |
|---|---|---|---|---|
| Africa | 22.7 (76) | 6.1 (20) | 0.0 (0) | 1.1 (4) |
| Asia | 19.4 (44) | 4.2 (9) | 8.1 (18) | 12.5 (28) |
| Europe | 2.2 (23) | 0.0 (0) | 0.6 (7) | 6.6 (70) |
| North America | 11.7 (53) | 0.0 (0) | 4.2 (19) | 6.1 (28) |
| Oceania | 3.8 (50) | 0.8 (11) | 0.3 (5) | 2.6 (34) |
| South America | 15.6 (88) | 0.0 (0) | 0.7 (4) | 1.5 (9) |
| World | 75.3 (58) | 11.1 (9) | 14.0 (11) | 30.5 (23) |