Compilation of Summaries 
32 
System Nordsee 
Organic Pollutants (p. 193 sqs.) 
Spatial distributions and temporal trends of the different organic pollutants varied also 
in 2006 and 2007, as expected. The main source of pollutants in the German Bight is 
riverine discharges by the river Elbe. Pollutant levels generally decrease more or less 
rapidly from the coast toward the open sea. 
Outside the Elbe plume, concentrations of non-polar pollutants normally are very low. 
Therefore, spatial distributions both of the highly lipophilic, chlorinated hydrocarbons 
HCB, PCB, and DDT, and of polycondensed PAH were characterized by a strong 
decrease of concentrations from the coast toward the open sea. Concentrations were 
found to depend strongly on the amount of suspended particulate matter present in 
the samples. 
As the limits of detection for PCB and DDT compounds among chlorinated hydrocar 
bons have been lowered, very low concentrations of these compounds have now also 
been found in the outer German Bight. PAH levels of sea water were comparable to 
those in earlier years; no temporal trend has been found. 
Robust trends have not been identified for most chlorinated hydrocarbons due to high 
fluctuations of their concentrations in sea water and because of the short observation 
periods. By contrast, concentrations of the hexachlorocyclohexane isomers a- and 
y-HCH decreased exponentially in the period from 1989 to 2007. Levels of a-HCH in 
the German Bight decreased by half every 4 years. Levels of y-HCH, however, initially 
decreased only by 5-35% in the monitoring area until about 1998, depending on 
location, after which they decreased by half every 2 years. Meanwhile, levels of both 
a- and y-HCH are far below 0.5 ng/L. In the area off the North Frisian coast, which is 
influenced by the Elbe plume, the long-term downward trend of a-HCH was replaced 
by a lateral trend as early as the turn of the Millennium. However, in the two years of 
the period under review, a downward trend set in again. 
The highest pollutant levels in the German Bight no longer are those of the classical 
lipophilic pollutants but of >novel< pesticides, which characteristically are mostly polar 
and persistent. Due to these properties, the substances behave rather »conservative 
's i. e. rather good inverse correlations between substance concentration and salinity 
apply in most cases, which support the conclusion that the main input sources are the 
major rivers discharging into the southern North Sea. Also in 2006 and 2007, levels 
of polar pesticides were subject to major seasonal fluctuations. It is not possible to 
identify time trends currently because analyses were not made routinely before 2000. 
Although concentrations of lipophilic pollutants in sediment are about 10 4 to 10 6 times 
higher than in sea water, source correlations or temporal trends can hardly be identi 
fied. Sediment concentrations of all compounds studied were subject to high fluctua 
tions which, even with normalization of concentrations to total organic carbon (TOC), 
could not be reduced sufficiently to allow any robust trends to be identified, also due 
to the short monitoring period of 12 years. 
It has been shown on the example of a novel class of pollutants - perfluorinated sur 
factants - that conclusions regarding long-term trends can be made retrospectively on 
the basis of undisturbed sediment cores taken in sediment provinces. 
Metals (p. 232 sqs.) 
Metal levels (Cd, Cu, Hg, Ni, Pb, and Zn, dissolved) measured in water samples from 
the German Exclusive Economic Zone (EEZ) in 2006 and 2007 were such that no ad