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During monitoring cruises of the BSH
vessels, samples of water, suspended particulate matter and sediment are
taken at stations of the existing monitoring network. Part of the samples are
processed and preserved on board for further analysis at the BSH’s laboratory
in Hamburg-Sülldorf. The results of the analyses are used in national and international
quality status reports (BLMP, OSPAR, HELCOM) and are published as information
to the general public.The BSH laboratory at Hamburg-Sülldorf also specialises
on determining the origin of oil spills at sea and on the coasts.
The following marine chemical data are collected and analysed at the laboratory:
Nutrients
Phosphate, nitrate, and silicate in sea water are essential trace substances
that are needed in the formation of proteins and the shell material of diatoms.
They are called nutrients because they promote growth. Too high nutrient input
may cause over-fertilisation of a body of water.
Organic pollutants
Most of the presently known chemical substances are organic compounds. About
2,000 of these substances are considered pollutants because they are either
toxic or are not biodegradable or may accumulate in the food chain. The BSH
routinely monitors some 100 organic substances.
Over the past years, the concentrations of most artificial radionuclides
in the North Sea have decreased, while in the Baltic Sea elevated concentrations
of the nuclide Cs-137 (caesium-137) are still measured today which exceed the
levels before the Chernobyl reactor accident in 1986, though with a clearly
decreasing tendency. Compared to the concentrations of natural radionuclides
in the marine environment, the levels of artificial radionuclides are extremely
low, so that hazards to flora and fauna or to human health due to the consumption
of fish or other seafood are not to be expected.
Heavy metals
Metals occur naturally in the marine environment. There are numerous metals
without which biological growth would not be possible. Organisms are adapted
to a certain range of individual element concentrations. If this range is exceeded,
negative impacts on the biotic communities within the ecosystem will occur.
Human activities have led to major releases of particular elements into the
environment and still continue to do so, causing natural background levels to
be clearly exceeded locally.
Dissolved oxygen
Dissolved oxygen in water is a precondition for higher life forms in the
ocean. The amount of dissolved oxygen in water is much smaller than in air (6.25
mg versus 300 mg per litre). While surface water is in permanent contact with
the air and normally has a high oxygen content, oxygen deficiencies are not
uncommon in the deepwater of the Baltic Sea.
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