Emissions to water of hazardous substances from urban sources
Assessment made on 01 May 2004
ClassificationWater (Primary theme)
Coasts and seas
- WHS 008
Policy issue: Are discharges of hazardous substances from urban sources to water decreasing?
Emissions of heavy metals from urban sources have decreased in the North Sea conference states region.
Emissions of hazardous substances in the Netherlands decreased during the 1990s.
However, due to variations in the urban sources taken into account and/or river flows, there is an important variability from year to year in the reported emissions of hazardous substances from urban sources in these regions.
Over the last 20 years, marked changes have occurred in the proportion of the population connected to waste water treatment as well as in the waste water treatment technology involved. There have also been some changes in other sectors, such as the increased use of lead-free fuels. These changes have led to decreases in the emission of hazardous substances to water from urban sources. This is particularly emphasised by the downward trend in the emission of heavy metals in the North Sea conference states area. However, the trend for other hazardous substances is less clear, for example in the Netherlands. The increase in the treatment of waste water, leads in turn to an increase in the quantities of sludge produced. The sludge is disposed of by spreading on soils, depositing in landfills or incineration, which can result in the transfer of heavy metal pollution from water to soil or air.
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