Marine Chemistry 
Nordseezustand 2004 
23 
in the Fair Isle Current at the NW boundary to the North Atlantic undergoes quasi-cy- 
clic variations at periods of 6 to 9 years, which stand out in the variance spectrum of 
the NAO-index as well. This quasi-cycle was at maximum in 2004. 
The runoff rates of Elbe River remained below climate normals almost throughout the 
year. These low flow volumes, which persisted since April 2003, were continuing con 
sequences of the extreme dry-year 2003. Precipitation, which was about normal for the 
catchment area of the Elbe River, probably was used foremost in replenishing ground- 
water reserves. The temporal course of salinity at Helgoland Roads was mostly anti 
parallel to that of Elbe River runoff. Hence, monthly salinities exceeded climatological 
means here most of the time. 
Marine Chemistry 
Within its chemical monitoring programme, BSH carried out five monitoring campaigns 
in the German Exclusive Economic Zone (EEZ), largely corresponding to the German 
Bight. Samples of sea water, suspended particulate matter, and sediment were either 
analyzed on board the vessel or preserved for laboratory analyses at a later date for a 
variety of substance groups. In 2004, monitoring activities outside the EEZ were only 
possible during the North Sea overall survey in July/August and, for logistical rea 
sons, were limited to nutrient sampling and associated variables such as chlorophyll- 
a and oxygen. 
Comprehensive monitoring of the chemical pollution of sea water with nutrients, trace 
metals, artificial radionuclides, pesticides, and other organic pollutants was carried out 
in the German Bight and provided a good spatial overview of the present situation. In 
addition, concentrations of trace metals and organic pollutants were determined in 
sediment samples. 
The main source of most substances and compounds here is riverine inputs, especial 
ly by the Elbe River. Since the general circulation in the German Bight is cyclonic, sub 
stances tend to spread in northwesterly direction (Elbe River plume), while concentra 
tions decrease through mixing with less polluted sea water. Spatial concentration 
patterns thus are the more similar to the salinity distribution the more dominant this 
mixing process is (e. g. nutrient distributions in times of low biological activity). 
Deviations particularly show in stronger concentration gradients toward the open sea 
than would be expected with conservative dispersion. They often result from a strong 
tendency of some substances to attach to suspended particulate matter (SPM affinity). 
This property brings about a relatively fast decrease in substance concentration in the 
water column at the expense of substance enrichment in sediments through SPM pre 
cipitation. Hence, pollutant levels in sediments often considerably exceed those in sea 
water. 
On the one hand, high sediment pollutant levels prove that the subsystem >seabed< is 
a sink for many substances entering the subsystem >sea water< from external sources. 
On the other hand, sediment also is an internal source of these same substances for 
the total system because strong, storm and tide induced currents and turbulence are 
causing continuous sediment transports and resuspension in the largely shallow and 
sandy regions of the North Sea. For instance, only a fraction of the current volume ac 
tivities of radioactive substances in the German Bight is due to recent, reduced dis-