Metal (mg/L) | Sampling time | Annual average | Standards of environmental protection organization | |||||
Spring | Summer | Fall | Winter | Sewage to ground waters | Sewage to absorption wells | Agricultural and irritation usages | ||
Lead | 0.157 | 0.165 | 0.090 | 0.120 | 0.133 | 1 | 1 | 1 |
Copper | 0.210 | 0.230 | 0.103 | 0.098 | 0.160 | 1 | 1 | 0.2 |
Nickel | 0.293 | 0.354 | 0.238 | 0.205 | 0.273 | 2 | 2 | 2 |
Chromium | 0.017 | 0.009 | 0.009 | 0.012 | 0.012 | 0.5 | 1 | *1 |
2 | 2 | *2 | ||||||
Zinc | 0.070 | 0.060 | 0.098 | 0.049 | 0.069 | 2 | 2 | 2 |