The number of organic substances, either produced by the chemical industry for the most diverse range of purposes or produced as a result of different processes, is immense. Because of their persistence, their tendency to accumulate in organism and their often worldwide distribution there are about 2000 substances that are classified as potentially environmentally relevant.

From a superregional perspective organic substances, with a few exceptions, are not very important in the Weser river basin (see map chemical status). But it must be considered that stricter quality objectives can change this assessment. Until now some pestizides, organotin compounds as well as some PAHs have been found regionally. The values of the pesticides Diuron, Isoproturon and MCPA exceed the quality objectives of the WFD, most of all in small waters. Regarding the PAHs, the two congeners Benzo(ghi)perylen and Indeno(1.2.3-cd)pyren are widely found. Furthermore, tributyltin (TBT) is found most of all in the Lower Weser.

The list of substances to be tested is adjusted to the current level of knowledge.

Data organic pollutants
in the (in German)