Eutrophying substances in marine surface water in the Netherlands, 1985-2001

The nitrogen and phosphorus levels in the Western Scheldt fell in the period 1985-2001. Levels also fell or remained stable in other brackish and marine surface waters.

Developments for eutrophying substances in brackish and marine surface water

The nitrogen level in the Western Scheldt and Eems-Dollard has been higher than in other brackish waters for years. The level in the Western Scheldt and Eems-Dollard fell in 2001 compared to 1985.
The phosphate level in the Western Scheldt is also high, but it has been falling for some time. This fall would seem to have come to an end now. There has been a fall or stabilisation in other brackish waters.

Policy relating to eutrophying substances in brackish and marine surface water

There are no standards for eutrophying substances (nutrients) in brackish and marine water. The government has adopted the goal of reducing concentrations to a level at which there will be no negative impact on the ecosystem of the North Sea.

Relevance

Excessive levels of eutrophying substances will harm the ecosystem in the North Sea. This can result in all sorts of undesirable effects such as algal bloom and therefore the formation of foam.

Technical note

The data for nitrogen relate to dissolved inorganic nitrogen (the jargon term is 'DIN'), which is the inorganic nitrogen in filtered water. This is also true, mutatis mutandis, for phosphorus: the figures relate to dissolved inorganic phosphorus ('DIP').

The graph shows the median for the winter values. The winter values are measurements made between 1 December and 1 March. Winter values are representative for the natural level of nutrients because biological activity is minimal in the winter. The median is the value above which 50% of the observations are found. This is the middle value which is measured; not the average value.

References

• RIKZ, monitoringsprogramma Rijkswaterstaat.

Relevant sections and indicators in the Environmental Data Compendium

• Surface water quality: Policy
• Eutrophying substances in fresh surface water in the Netherlands, 1985-2001
• Eutrophication of fresh water in the Netherlands, 1999
• Emissions into water in the Netherlands, 1990-2001
• Discharges into water and burden on surface water in the Netherlands, 1990, 1995, 1999 and 2000
• Emissions to water by the Dutch Agriculture and horticulture target sector, 1990-2001
• Guide to Environmental theme of Eutrophication

Relevant information outside of the Environmental Data Compendium

• Information about current and future developments can be found in Environmental Balance 2002 and Nationale Milieuverkenning 2000-2030.
• More information about the monitoring of nationally managed waters.