Chemical brownfields: forest soil is very slow to forget

New map shows old pollutant loads

photo of a forestClick to enlarge
Forest soil stores pollutants, so it is a good indicator of environmental pollution.
Source: Alekss /

Forests cover 30% of Germany's land area and fulfil a number of important functions: they are the habitat of plants and animals, they produce oxygen and their soil purifies rainwater. But forest soil also stores pollutants, making it a good indicator of environmental pollution. A new Federal Environment Agency (UBA) interactive map shows the levels of contamination by persistent organic pollutants in forest soil.

Polycyclic aromatic hydrocarbons which have been released into the environment for decades from hard coal and lignite mining activities, the oil industry and household and industrial chimneys are in forest soils, and so are polychlorinated biphenyls (PCB) which have been banned in Germany for more than 30 years. DDT – an insecticide which has been banned for a long time and was last sprayed in Germany in 1985 to control the bark beetle in Brandenburg's pine forests – can still be traced today.

The map data reflect the use of chemicals and pollutant emissions in both parts of Germany: there are higher concentrations of substances which in part have been banned for a long time, in particular at former industrial sites in Saarland, the Ruhr area and the Bitterfeld-Wolfen chemical triangle. The good news is that the levels recorded at most sites are below the precautionary values of the Federal Soil Protection and Contaminated Sites Ordinance.

"Our soil pollutant data do not indicate any direct threat to the population, but we cannot give the all-clear either. Once persistent are released into the environment they are stored in soil and are slowly released for decades", said President Maria Krautzberger of UBA. The example of DDT is a clear example: contamination is not contained to the area where it was sprayed, it can also be traced in further surroundings.

The new map is based on the National Forest Soil Survey project, a joint initiative of environmental and forest administration at the federal and Länder level.

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