Parameter | 1966 | 1977 | 1979 | 1984 | 1989 | 1990 |
PO4 (µg/l) | 7 - 120 | 1 - 122 | | 2 - 75 | 4.0 - 37 | 1 - 19 |
NO3 (µg/l) | 10 - 112 | 0.5 - 122 | 0.16 - 0.18 | 21 - 237 | 0.1 - 513 | 1 - 30 |
SO4 (mg/l) | 0.4 - 4.0 | | | 0.1 - 5.0 | | |
SiO2 (mg/l) | 4 - 8 | 0.2 - 3 | 2 - 7.9 | 0.1 - 7.6 | | 0.06 - 0.72 |
PP (mg DO/m3) | 100 - 130 | | 400 - 600 | | 180 - 600 | 100 - 1400 |
Chlorophyll(µg/l) | 0.5 - 22.3 | 2.1 - 8.5 | | 1.8 - 23.5 | 8 - 120 | 35.8 - 115.2 |