s.s
Conclusions
A.R.D. Stebbing . R.l. Willows
1. The perceived state of the North Sea is one of significant local contamination, with
evidence of some pollution related to the coastal margins, estuarine inputs, and areas of contaminant accumulation.
2. The definition of pollution is considered from both chemical and biological perspectives; only the latter incorporates a meaningful concept of the environmental
effects of pollution.
3. Where biological techniques to measure pollution effects have been deployed on appropriate geographic scale, they demonstrate that significant gradients of pollution exist
in the North Sea that have not been defined using chemical monitoring techniques.
4. We propose a definition for assimilative capacity as the balance between those processes
that determine the concentration of contaminant in an environmentally meaningful compartment. Assimilative capacity is exceeded when a critical threshold ofbiological effect is exceeded (Le. there is pollution), or when the rate of input of a contaminant would lead to such a threshold being exceeded in the future (Le. there will be pollution). We identify some of the component processes that may act in the North Sea.
5. We argue that the assimilative capacity of the North Sea is a resource of considerable economic value. There may be an optimal economic level of utilisation of this
environmental service that does not damage its component processes.
6. The use of biological effects techniques that demonstrate that pollution gradients
exist that traverse large areas of the North Sea, and from estuarine plumes to its centre, indicate that assimilative capacity is being exceeded.
7. Existing legislation is orientated to regulating the release of potential pollutants.
Further legislation sets chemical EQSs and this determines the use of monitoring
effort. This does not provide the most appropriate basis for controlling pollution
because links between chemical contamination and its biological impact are often
ignored or poorly understood.
8. New contaminants are often not detected as pollutants until they have an impact in the
environment; they are recognized through their effects rather than by chemical analysis. Nevertheless investigative chemistry must be included to detect incipient problems.
9. Therefore we advocate the use of biological monitoring techniques that relate to
accepted criteria for environmental quality. Such techniques, if strategically deployed,
are sufficiently sensitive to provide both detection and early warning of incipient
environmental problems. Chemical analyses can then be focussed to establish the
causative contaminants.
10. Biologically-based legislation (biological or ecological water quality objectives and
standards) that is formulated to protect assimilative capacity, and thereby prevent
pollution, would ensure that monitoring effort is more appropriately focussed.
Acknowledgements
We are grateful for critical comments of this chapter from Dr. Peter Donkin, Dr. John
Widdows and Miss Nicola Beaumont; to Dr. John Harris and Prof. Geoffrey Millward
for advice on sediment/water partitioning and to Mr. Fred Staff and Mr. Martin Carr
for help in preparing figures.
Conclusions
A.R.D. Stebbing . R.l. Willows
1. The perceived state of the North Sea is one of significant local contamination, with
evidence of some pollution related to the coastal margins, estuarine inputs, and areas of contaminant accumulation.
2. The definition of pollution is considered from both chemical and biological perspectives; only the latter incorporates a meaningful concept of the environmental
effects of pollution.
3. Where biological techniques to measure pollution effects have been deployed on appropriate geographic scale, they demonstrate that significant gradients of pollution exist
in the North Sea that have not been defined using chemical monitoring techniques.
4. We propose a definition for assimilative capacity as the balance between those processes
that determine the concentration of contaminant in an environmentally meaningful compartment. Assimilative capacity is exceeded when a critical threshold ofbiological effect is exceeded (Le. there is pollution), or when the rate of input of a contaminant would lead to such a threshold being exceeded in the future (Le. there will be pollution). We identify some of the component processes that may act in the North Sea.
5. We argue that the assimilative capacity of the North Sea is a resource of considerable economic value. There may be an optimal economic level of utilisation of this
environmental service that does not damage its component processes.
6. The use of biological effects techniques that demonstrate that pollution gradients
exist that traverse large areas of the North Sea, and from estuarine plumes to its centre, indicate that assimilative capacity is being exceeded.
7. Existing legislation is orientated to regulating the release of potential pollutants.
Further legislation sets chemical EQSs and this determines the use of monitoring
effort. This does not provide the most appropriate basis for controlling pollution
because links between chemical contamination and its biological impact are often
ignored or poorly understood.
8. New contaminants are often not detected as pollutants until they have an impact in the
environment; they are recognized through their effects rather than by chemical analysis. Nevertheless investigative chemistry must be included to detect incipient problems.
9. Therefore we advocate the use of biological monitoring techniques that relate to
accepted criteria for environmental quality. Such techniques, if strategically deployed,
are sufficiently sensitive to provide both detection and early warning of incipient
environmental problems. Chemical analyses can then be focussed to establish the
causative contaminants.
10. Biologically-based legislation (biological or ecological water quality objectives and
standards) that is formulated to protect assimilative capacity, and thereby prevent
pollution, would ensure that monitoring effort is more appropriately focussed.
Acknowledgements
We are grateful for critical comments of this chapter from Dr. Peter Donkin, Dr. John
Widdows and Miss Nicola Beaumont; to Dr. John Harris and Prof. Geoffrey Millward
for advice on sediment/water partitioning and to Mr. Fred Staff and Mr. Martin Carr
for help in preparing figures.