Report
Polarstern Zhiyongxie 01

Searching for emerging organic pollutants: a report from scientists from the Department of "Environmental Chemistry" about their expedtition with the research vessel POLARSTERN. Read now


Institute of Coastal Research
Coasts, Climate and Society

Environmental Chemistry

The ocean's contaminant detectives

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Photo: iStock/3quarks

What kind of biochemical processes take place in the coastal area and how big is the hazard posed by contaminants? To answer these questions, the researchers at the Helmholtz-Zentrum Geesthacht take water, sediment and air samples, analyse them using state-of-the-art testing methods and combine the results with detailed computer calculations.

Some contaminants, such as those from impregnation or fireproofing agents, are exceedingly long-lived and build up in the marine food chains. It remains uncertain how they end up in the environment and how toxic they are to living organisms. The same applies to the substitutes for banned substances. The HZG researchers use the ‘Coastal Chemistry Platform’ to hunt down such contaminants, trace back possible sources and propagation paths and define potential problem zones.

Mysterious seabed

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A video sled provides images on the typography of the sea floor. Photo: HZG/Christian Schmid

The seabed plays a special role in the coastal ocean. It represents the ‘memory of the sea’ and serves as an archive of past environmental conditions. At the same time, the seabed provides a habitat for countless plants and creatures, but can also accumulate and store contaminants. For some substances the sediments act as a kind of treatment plant, where natural processes attenuate environmentally problematic substances.

In order to better understand these processes, the HZG coastal researchers examine the detailed structure of the marine sediments. To do this, they take ground samples or position landerson the seabed – wardrobe-sized metal frames filled with measurement technology. These remain on the seabed for a long period of time.

The samples are analysed in the HZG’s well-equipped laboratories, which are open to external researchers, particularly experts from the universities. The scientific findings are collated in the ‘„coastMap“.’ marine data portal. This provides a constantly updated overview of the physical, biogeochemical and biological condition of the
seabed.

Sediments act as treatment plants

Also of relevance are the nutrients that are released from agricultural fertilisation and washed into the sea via the rivers or the atmosphere. Here the experts investigate the amount of nutrients that the seabed can hold or neutralise in its capacity as a treatment plant. They assess whether an excess of nutrients causes algal blooms and the extent to which human intervention compromises the seabed’s ability to act as a treatment plant. Furthermore, the scientists examine the extent to which extreme events churn up the seabed, releasing the nutrients and contaminants stored in the sediment.

And they study the potential consequences of a further deepening of the Elbe. Is there a risk of the estuary silting up under certain circumstances? Could this create oxygenfree zones in some areas – in Hamburg Port, for example?

Mission: searching for pollutants in the Baltic Sea

44 stations, eight ports and one ship: Scientists from the Department for Environmental Chemistry at the Institute of Coastal Research are on a ten-day sampling campaign from Peenemünde to Flensburg – on the HZG research ship LUDWIG PRANDTL. The researchers are taking samples along the coast of the Baltic Sea and the important riverine inflows to investigate levels and distribution of pollutants.