Institut für Fischereiökologie
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Determination of PAH-Metabolites in bile fluids of fishes
If we think of contaminants in fish, we think of human consumption first. But who knows what these contaminants mean for the fish? Does the animal suffer from enviromental pollution?
To evaluate this problem, you have to know the concentration of the contaminant very well and observe it over a longer period of time. These regularly performed measurements in the environment are called monitoring. To do this in marine fish is one of the tasks of the Thünen Institute of Fisheries Ecology. Scientists of the institute produce monitoring data for more than 20 different contaminants in marine fish. Among these substances are PAH metabolites, derived from polycyclic aromatic hydrocarbons (PAH). PAH metabolites are water soluble degradation products found in the bile of fish. Chemists of the Thünen Institute of Fisheries Ecology measure the concentration of these Substances as part of routine monitoring program of the marine environment. The results become part of the evaluation of the environmental status of North Sea and Baltic Sea respectively.
PAHs are not invented by chemical industries. They are a natural part of the environment since coal, oil and anoxic combustion processes exists. Further on these substances are persistent at the seafloor and are continuously released into the sea by rivers, oil drilling platforms, shipping as well as from other sources. The result of this situation is a relatively constant regional contamination pattern of PAH in the marine environment.
We determine PAH metabolites in the bile fluids of several fish species, caught for monitoring on the reserach vessel Walther Herwig III. Other samples come form the European data collection framework -eel:
Our method comprises an enzymatic treatment of fish bile, followed by a liquid chromatography separation and a fluorimetric detection. We determine the concentration of contaminants in our samples with certified standards. As supporting parameter we measure the colour of the bile photometrically. The result is given in ng/ml for every single fish.
Low levels of PAH metabolites are typical for fish caught in the open North Sea or in the Barents Sea. These concentrations are in the range of background contamination as we know it for fish from Greenland or antarctic waters. In general no negative effects of PAH can be expected for fish living off-shore and far away from point sources. Higher PAH metabolite concentrations could be found in animals living close to the German coastlines in North Sea and Baltic Sea. Elevated PAH concentrations in these regions are due to shipping activities and river discharges. In single cases the concentrations are high enough to raise concern. But most fish investigated in marine and coastal waters are in good conditions, at least regarding PAH. That are good news.
The eel caught in German rivers is higher contaminated, as could have been expected. That is a result of the higher contamination level of the rivers compared to the sea but also influenced by the special biology of the eel.
It could be shown In laboratory experiments that sediment bound contaminants like PAH become bioavailable for fish during resuspension. Scenarios like this are important with regard to flood events. One result among others was a correlation between a single PAH metabolite in fish bile and the number of micronuclei (DNA abberrations in blood cells) after an exposition to PAH contaminated sediment.
Permanent task 1.1998 - 12.2020
Results 1 - 5 of 29
Results 1 - 5 of 29