Emissions of radioactive contamination from Fukushima in 2011 have not had consequences for the Barents Sea. It takes at least 15 years to transport ocean currents from Japan to Norway, and during that time the contamination will be diluted to levels that will be virtually impossible to detect in Norwegian fish and seafood. However, a similar serious accident closer to Norway could cause the levels of radioactive contamination in the marine environment to increase.
One of the main manmade radioactive substances is Cesium-137 (Cs-137). It is difficult to speculate how much the levels of Cs-137 could increase in the event of an accident, but it is highly unlikely that the levels in saltwater fish and seafood will exceed the limit of 600 Bq/kg for radiocesium (Cs-134 + Cs-137) in foodstuffs set by the Norwegian Food Safety Authority. Even if the levels do not exceed the limit, Norwegian fish would probably get a poor reputation, which could have major negative consequences for the Norwegian seafood industry and export trade. This will be of great significance for the man commercial fisheries in the Barents Sea.
The figure below shows the radioactivity in fish in the Barents Sea in the period from 1961 to 1968. The highest activity was measured in 1962-1963, which was attributed to a "peak" in the fallout from atmospheric nuclear tests in 1961-62. Owing to a cessation of atmospheric nuclear tests, biological elimination and short half-lives of some of the radioactive substances, the activity levels in fish decreased towards the end of the 60s. Like many other laboratories, IMR stopped monitoring of radioactivity in the late 1960s. When the Chernobyl accident occurred on 26 April 1986, laboratories in Norway were generally poorly equipped with instruments to measure radioactivity and very few people were able to perform such measurements. IMR’s monitoring of radioactivity in Norwegian waters resumed in the early 1990s, while a national monitoring programme for radioactivity in the marine environment was started in 1999. This programme is coordinated by the Norwegian Radiation Protection Authority.
We know that the concentration of Cs-137 in fish from the Barents Sea is now generally lower than 1 Bq/kg fresh fish (see figure below, which shows the concentration of Cs-137 in cod in maritime areas). This is considerably lower than the limit of 600 Bq/kg. Measurements made today are not directly comparable with those from the 1960s, but a high proportion of the activity that was measured at the time stemmed from Cs-137. Consequently, we can conclude with relatively high level of certainty that the concentrations are much lower today than in the 60s.
What do we do now?
We conduct a detailed study of radioactivity in the Barents Sea every third year. In the intervening years, we conduct similar studies in the North Sea and Norwegian Sea. As part of this year’s Barents Sea Ecosystem Survey, personnel from the Norwegian Radiation Protection Authority and IMR are onboard the research vessels Johan Hjort and G. O. Sars to take samples of marine organisms, sediments and seawater in the Barents Sea. The samples will be analysed for substances including radioactive caesium, strontium, plutonium and americium, as well as naturally occurring nuclides such as radium and polonium. The annual survey of the wreck of the sunken Russian submarine Komsomolets will be carried out from G. O. Sars in September. Analyses of radioactive substances are often time consuming and it is expected to take about a year to complete all the analyses. The results will be published in reports including the Marine Research Report and radiation protection reports. The data will also be reported to OSPAR, AMAP, MOSJ and miljøstatus.no. In addition, the data is also used in resource management plans for Norwegian waters.
Why continue the monitoring?
Unfortunately accidents occur at regular intervals that can result in the release of radioactive waste into the marine environment. Examples of such accidents in the Barents Sea are the shipwrecks of the Russian nuclear-powered submarines Kursk and K-159 in 2000 and 2003 respectively. Consequently, it is of great importance that we have competent personnel and equipment to study the consequences of such accidents.
The marine monitoring programme has so far not detected any radioactive contamination from the shipwrecks of Kursk and K-159.
Kursk was raised, but K-159 still lies at a depth of nearly 250 m off the coast of the Kola Peninsula and, as such, represents a potential source of radioactive contamination. This also applies to large quantities of radioactive waste that has been dumped in the Barents Sea and the Kara Sea. No environmental consequences stemming directly from this have been proven so far. To the contrary, the Barents Sea is considered among the cleanest seas in the world. However, we must be able to document the levels of radioactive contamination in Norwegian fish and seafood at all times, and in order to achieve this we need to conduct regular monitoring.