KEMA biologists are specialists in environmental risk assessments, such as studies on the effects of cooling water on fish populations or other aquatic organisms. Besides the topics mentioned here below, there are a variety of field research and desk studies we can perform.

• hydro power impact on fish:  Fish damage by passage through turbines of hydro power plants. For example, we have studied the relatively high percentage of damage to silver eel (mature eel migration to the sea)
• preventing blockage of cooling water sieves:  Preventing clogging of rotating screens by juvenile fish or jellyfish. In the case of large jellyfish (10L species) a solution is found in air lifting equipment. Part of this problem is modelled to predict when problems can be expected
• population studies on fish in surface waters:  Specific biological studies for environmental impact studies and for governmental studies i.e. the fish species composition in the different harbours of Rotterdam
• reducing damage to aquatic organisms:  Studies for improvements in wash-off systems for screens and locations for cooling water inlets (surface or specific deep intakes) to reduce the entrainment and impingement of fish
• fish deflection techniques with light and sound:  Underwater sound systems and (strobe) light systems can be an effective solution, deflecting fish from the water entrances, by forcing them to migrate via an alternative route.

As a consequence of the accident of the Chernobyl nuclear power station in the Ukraine in 1986, many areas in Europe were contaminated with radioactive materials. One of the concerns was the contamination of inland surface water with 137Cs, a radionuclide with a long half-life of 30 years. 

Immediately after this accident, KEMA started a field study in the IJsselmeer, the biggest fresh water lake in the Netherlands. In the period 1992 – 2000 KEMA participated in several EU-projects in the Ukraine, Russia and Belarus. These studies focussed on the distribution of 137Cs in the aquatic food chain, processes governing the accumulation and elimination of 137Cs in fish and development of countermeasures against the uptake of radiocaesium. 

Material was collected by taking samples of water, sediment, plankton, macrofauna and fish in lakes and rivers. Concentration of 137Cs in the samples was measured in the KEMA laboratories by gamma spectrometry in semiconductor detectors. 

Highest levels of 137Cs were found in sediment with high lutum content, in predatory fish species such as perch and pike and in the older-year classes of predatory fish. Contamination levels in fish in the IJsselmeer (the Netherlands) were clearly below the EU standard of 600 Bq/kg.wet weight. In contrast, in Belarus contamination levels up to 100,000 Bq/kg were found in perch in Lake Svyatoe Kostyukovichy, located in the controlled zone of the Chernobyl area. In this lake, countermeasure experiments were carried out including the addition of potassium fertilizer to the lake. The method of application of the potassium to the lake during the period of ice cover was found to be very successful. The 137Cs activity in fish seemed to decrease to around 40% of the pre-countermeasure values in a number of different fish species. The rate of reduction observed exceeded expectations. Our expertise in this area includes:

• impact assessment and modeling of radioactive contamination in aquatic systems 
• monitoring aquatic ecosystems: water, sediment, plankton, macrofauna and fish
• measuring radioactivity with modern equipment 
• experience with expeditions to remote areas.