Scavenging of select radionuclides and trace elements by pelagic Sargassum in the Caribbean Sea.

In recent years, the North Atlantic and the Caribbean Sea have experienced unusual and unprecedented pelagic Sargassum blooms, which may adversely affect coastal ecosystems and productive ocean. Sargassum has the potential to scavenge trace elements and radionuclides from seawater, and when bioaccumulated and thus concentrated, can pose a potential threat to higher trophic organisms, including humans that consume impacted seafood. In this study, trace elements and naturally-occurring U/Th-series radionuclides were measured in Sargassum that were collected in the coastal waters of the Caribbean Sea (Antigua/Barbuda, Belize, and Barbados) to better define baseline concentrations and activities, and to assess the scavenging potential for these trace elements and radionuclides. The mean concentration of trace elements observed in Sargassum collected across these three Caribbean Sea are ranked accordingly to the following descending order: Sr > As>Fe > Mn > Zn > Ni > V > C > Cd > Se > Co > Cr > Pb > Ag > Hg. 210-Po and 210Pb activities in Sargassum were observed to be more elevated than previously reported values.

Hg and 210Po in consumed fish of the Tadjoura Gulf (Djibouti): Levels and human health risk assessment.

Hg and 210Po were measured in the muscle tissue of commercially important fish species collected in the main coastal cities of the Djiboutian coast (Tadjoura Gulf) to evaluate the potential risk associated with their consumption. The levels of Hg among the different species ranged from 0.02 to 1.69 mg/kg w.w and exceeded tolerable limits as reported by the national regulation (2000-0727/PR/MAEM) and the Codex Alimentarius. The probabilistic distributions of health hazard were evaluated through Monte-Carlo simulation, which confirmed the carcinogenic risk from Hg. The levels of 210Po ranged from 4.1 to 134.5 Bq/kg w.w among muscle tissues of the eight commercially important species. The carcinogenic risk was in an unacceptable range and simulation revealed that children were the most vulnerable population. The results obtained confirms that the health impact is reduced when consuming two servings per week.

IAEA proficiency tests for determination of radionuclides in sea water.

The International Atomic Energy Agency organised four proficiency tests between 2012 and 2015 to test the performance of participating laboratories in an analysis of radionuclides in sea water samples. These exercises were initiated to support IAEA Member States in sea water analyses of tritium, strontium-90 and caesium isotopes in relation to the accident at the Fukushima Daiichi nuclear power station, in March 2011, and subsequent contamination of the marine environment.

Main results of the 2012 joint Norwegian-Russian expedition to the dumping sites of the nuclear submarine K-27 and solid radioactive waste in Stepovogo Fjord, Novaya Zemlya.

This paper reports the main results of the 2012 joint Norwegian-Russian expedition to investigate the radioecological situation of the Stepovogo Fjord on the eastern coast of Novaya Zemlya, where the nuclear submarine K-27 and solid radioactive waste was dumped. Based on in situ gamma measurements and the analysis of seawater and sediment samples taken around the submarine, there was no indication of any leakage from the reactor units of K-27. With regard to the radioecological status of Stepovogo Fjord, activity concentrations of all radionuclides in seawater, sediment and biota in 2012 were in general lower than reported from the previous investigations in the 1990s. However in 2012, the activity concentrations of (137)Cs and, to a lesser extent, those of (90)Sr remained elevated in bottom water from the inner part of Stepovogo Fjord compared with surface water and the outer part of Stepovogo Fjord. Deviations from expected (238)Pu/(239,240)Pu activity ratios and (240)Pu/(239)Pu atom ratios in some sediment samples from the inner part of Stepovogo Fjord observed in this study and earlier studies may indicate the possibility of leakages from dumped waste from different nuclear sources. Although the current environmental levels of radionuclides in Stepovogo Fjord are not of immediate cause for concern, further monitoring of the situation is warranted.

Radiological status of the marine environment in the Barents Sea.

This paper presents the results of Norwegian radiological monitoring of the Barents Sea in 2007, 2008 and 2009. Activity concentrations of the anthropogenic radionuclides (137)Cs, (90)Sr, (239,240)Pu and (241)Am in seawater were low and up to an order of magnitude lower than in previous decades. Activity concentrations of (99)Tc in seawater were low but remain elevated compared to levels prior to the increased discharge of this radionuclide from Sellafield in the 1990s. Activity concentrations of the naturally occurring radionuclide (226)Ra in seawater were comparable to expected background values. Activity concentrations of (137)Cs in surface sediments were low, with higher values observed in sediments from coastal areas along the Norwegian mainland than from locations in the open sea. Activity concentrations of (137)Cs and (99)Tc in marine biota were low and up to an order of magnitude lower than in previous decades. Committed effective dose rates to man from anthropogenic radionuclides via the consumption of seafood from the Barents Sea were low and are not a cause for concern. Weighted absorbed dose rates to biota from anthropogenic radionuclides were low and orders of magnitude below a predicted no effect screening level of 10 µGy/h. Dose rates to man from consumption of seafood and dose rates to biota in the marine environment are dominated by the contribution from naturally occurring radionuclides.