Copper and cadmium: inflow to the North Sea, 1990-2001
The inflow of copper to the North Sea increased in the early 1990s. In recent years, there has not been any clear trend for the inflow of copper and cadmium.
| 1990 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | ||
| 1 000 kg | ||||||||
| Copper | 359 | 455 | 458 | 450 | 560 | 494 | 658 | |
| of which | Rivers | 187 | 328 | 260 | 301 | 373 | 314 | 472 |
| Dredging sludge | 165 | 97 | 197 | 119 | 157 | 151 | 156 | |
| Other sources | 6.5 | 29 | 1.5 | 30 | 30 | 29 | 30 | |
| Cadmium | 10.7 | 12.6 | 11.6 | 17.3 | 18.7 | 13.5 | 19.5 | |
| of which | Rivers | 5.5 | 9.2 | 5.2 | 13 | 13.8 | 7.4 | 13.7 |
| Dredging sludge | 4.0 | 3.2 | 6.4 | 4.2 | 4.9 | 5.9 | 5.7 | |
| Other sources | 1.2 | 0.2 | 0 | 0 | 0 | 0.2 | 0.1 | |
| Source: RIKZ. | RIVM/EDC/Oct03 | |||||||
Inflow of copper and cadmium to the North Sea
The inflow of copper to the North Sea increased between 1990 and 1996. At the end of the 1990s, it looked as though the inflow was stabilising but there has not been any clear trend over the last three years. Nor is there any clear trend for the inflow of cadmium.
The annual fluctuations are mostly accounted for by annual variations in river flows.
Policy relating to concentrations of copper and cadmium
Government policy is geared towards reducing concentrations of toxic substances to the desired quality standard. In order to achieve this aim, emissions of many substances need to be reduced. A reduction of 50% in the levels of copper in surface water was required between 1985 and 1995. The required reduction for cadmium was 70%. These objectives have been more than met (V&W 1998).
Relevance
Cadmium is a heavy metal that is toxic for almost all organisms. Copper is an essential metal. In other words, excessively low concentrations have a negative effect on organisms, but excessively high concentrations are toxic.
