Vulnerability of Canadian aquatic ecosystems to nuclear accidents

ISSUES AND CHALLENGES IN ASSESSING ECOLOGICAL AND HUMAN HEALTH RISK FROM THE SITING OF SMRS IN CANADA

There are many issues and challenges in assessing ecological and human health risk from siting small modular reactors (SMRs) in northern or Arctic regions. Environmental guidance for Canadian nuclear facilities is largely derived from data and models relevant to temperate regions, with no explicit guidance or parameters for northern regions. International Atomic Energy Agency guidance provides some data and parameters for northern regions, but there remains a paucity of data and models. Although wildlife often comprise a major part of northern and Arctic diets, there are few data or transfer parameters for these ecosystems. Data and transport models are available for weapon test and Sellafield/La Hague fission products in northern oceans, but very little is known about circulation or fate and transport in estuarine and coastal areas typical of northern Canada. Baseline data, parameters, and models are needed for key processes and pathways to accurately assess ecological and human health risk.

Radiocesium in Canadian game Birds Harvested during 1989-95

A historic data set containing unpublished measurements of ¹³⁷Cs (radiocesium) in 238 pooled samples of pectoral muscle from 1892 birds representing 37 species was analyzed in order to determine if (i) birds were contaminated due to global weapons fallout and/or the Chernobyl accident, (ii) to understand baseline ¹³⁷Cs levels in birds across the country by examining potential effects of trophic position and geophysical region, and (iii) to determine if the harvested birds were safe to eat. Current work is taking advantage of this data set to improve capabilities to assess the impacts of releases of radionuclides on food chains of species harvested as country food. Samples obtained from 173 locations across Canada (including locations in the Arctic), mostly during the fall hunting seasons between 1989 and 1995, were analyzed by gamma spectrometry and decay-corrected for the date of collection. Various methods of correlating measurements with environmental ¹³⁷Cs levels and species' habits were explored in order to determine environmental radiological transfer factors. All ¹³⁷Cs measurements in the samples were much lower than the Health Canada (2018) guidance level for ¹³⁷Cs (1000 Bq kg^-1); therefore, there was no evidence of a human health risk with respect to radiocesium. Environmental transfer factors for six different foraging groups were determined.

Does Salinity Affect the Distribution of the Artificial Radionuclides 90Sr and 137Cs in Water of the Saline Lakes? A Case of the Crimean Peninsula

In the framework of radioecological monitoring, the features of the distribution of the post-Chernobyl nuclear power plant (NPP) accident artificial radionuclides of 137Cs and 90Sr in the Crimean saline lakes were studied. Samples were collected from 12 Crimean lakes with a salinity range from 2 to 400 g/L in 2014–2017. Concentration of 90Sr varied from 5.9 to 313.6 Bq/m3, and 137Cs from 0.8 to 106.7 Bq/m3. Closing of the North Crimean Canal resulted in a decrease in radionuclide concentration in the lakes. About 61% of the total variability of 90Sr and 33% of 137Cs in lake water can be explained by salinity changes. The salinity affects the behavior of radionuclides in water, mainly influencing their solubility, on isotope exchange between the solution and bottom sediments, and also, probably, through its influence on accumulation of isotopes by aquatic organisms. Salinity is not the alone factor determining the behavior of radionuclides in the lakes, it only acts by interacting with other factors.