PCBs and PAHs in suspended matter in marine surface water in the Netherlands, 1989-2001
Prior to 1990, there were significant falls in PCB levels in suspended matter in brackish surface water. Since then, PCB levels have been stable at most monitoring sites. PAH levels are more or less constant.
PCB and PAH levels stable in suspended matter
Until ten years ago, there were considerable falls in the levels of PCBs (polychlorinated biphenyls) in suspended matter. Since then, there has been stabilisation at most sites. Levels in the coastal zone vary unpredictably. One PCB (PCB 153) exceeds the desired quality standard in two of the five locations.
There is no trend for levels of PAHs (polyaromatic hydrocarbons). One of these PAHs (benzo(a)pyrene) is found at levels above the desired quality standard at all monitoring sites.
Policy relating to PCBs and PAHs
At the Third North Sea Ministers' Conference, it was agreed that the inflow of PCBs to the North Sea would be stopped completely and that measures would be taken in 1995 to ban and destroy these substances. The final time limit for countries that failed to fulfil this commitment was 1999.
The aim of Dutch policy is to reduce emissions of PAHs and PCBs. In the Netherlands, the production and use of PCBs are banned.
At the Fourth North Sea Ministers' Conference in 1995 in Esbjerg, it was agreed that anthropogenic PAH emissions to the North Sea would be reduced to half the 1985 level by 2000.
Relevance
PCBs are toxic substances that degrade with great difficulty. PCBs have been used for more than 50 years in industry and engineering. Transformers and capacitors with PCBs are still in use. The aim of government policy is to eliminate or clean this equipment as quickly as possible.
PAHs are tar-like substances produced during the incomplete combustion of substances that contain carbon such as fossil fuels, wood, tobacco and food. The key sources are industry, consumers (including emissions from open fires), traffic and agriculture. There are hundreds of PAHs. Most PAHs are toxic and carcinogenic, even though the probability of cancer as a result of exposure to PAHs is small (with the exception of smoking). PAHs are persistent: in natural conditions, they degrade only slowly.
Technical note
Given the fact that PAHs and PCBs bond tightly to suspended matter, the levels of these substances in suspended matter are generally higher than in water.
Experts in the field of water generally use the median to determine trends. The median is the value above which 50% of the observations are found; the middle measured value - this is not the average value.
References
Relevant sections and indicators in the Environmental Data Compendium
- Surface water quality: Policy
- Emissions into water in the Netherlands, 1990-2001
- Discharges into water and burden on surface water in the Netherlands, 1990, 1995, 1999 and 2000
- Dioxins, furans and PCBs in breast milk of mothers in the Netherlands, 1988-1998
- PCB and mercury in eels in the Netherlands, 1980-2000
- Species in the Netherlands under pressure from stress/environmental stress, 1950-2000
Relevant information outside of the Environmental Data Compendium
- More information about the monitoring of nationally managed waters.
