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Bioaccumulation of tritiated water in phytoplankton and trophic transfer of organically bound tritium to the blue mussel, Mytilus edulis
Stockholm University, Faculty of Science, Department of Systems Ecology. (Marine Ecotoxicology)
Stockholm University, Faculty of Science, Department of Systems Ecology.
2013 (English)In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 115, 28-33 p.Article in journal (Refereed) Published
Abstract [en]

Large releases of tritium are currently permitted in coastal areas due to assumptions that it rapidly disperses in the water and has a low toxicity due to its low energy emissions. This paper presents a laboratory experiment developed to identify previously untested scenarios where tritium may concentrate or transfer in biota relevant to Baltic coastal communities. Phytoplankton populations of Dunaliella tertiolecta and Nodularia spumigena were exposed at different growth-stages, to tritiated water (HTO; 10 MBq l(-1)). Tritiated D. tertiolecta was then fed to mussels, Mytilus edulis, regularly over a period of three weeks. Activity concentrations of phytoplankton and various tissues from the mussel were determined. Both phytoplankton species transformed HTO into organically-bound tritium (OBT) in their tissues. D. tertiolecta accumulated significantly more tritium when allowed to grow exponentially in HTO than if it had already reached the stationary growth phase; both treatments accumulated significantly more than the corresponding treatments of N. spumigena. No effect of growth phase on bioaccumulation of tritium was detectable in N. spumigena following exposure. After mussels were given 3 feeds of tritiated D. tertiolecta, significant levels of tritium were detected in the tissues. Incorporation into most mussel tissues appeared to follow a linear relationship with number of tritiated phytoplankton feeds with no equilibrium, highlighting the potential for biomagnification. Different rates of incorporation in species from a similar functional group highlight the difficulties in using a 'representative' species for modelling the transfer and impact of tritium. Accumulations of organic tritium into the mussel tissues from tritiated-phytoplankton demonstrate an environmentally relevant transfer pathway of tritium even when water-concentrations are reduced, adding weight to the assertion that organically bound tritium acts as a persistent organic pollutant. The persistence, potential for biomagnification and the increased toxicity of organic tritium increases the potential impact on the environment following a release of HTO; current legislation does not adequately take into account the nature of organic forms of tritium and therefore may be underestimating accumulation and toxic effect of tritium in the environment. Such information is necessary to accurately assess the distribution of tritium following routine releases, and to adequately protect the environment and humans.

Place, publisher, year, edition, pages
2013. Vol. 115, 28-33 p.
Keyword [en]
HTO, Organically bound tritium, Bioaccumulation, Phytoplankton, Mussel
National Category
Biological Systematics
URN: urn:nbn:se:su:diva-84814DOI: 10.1016/j.jenvrad.2012.07.008ISI: 000311527800004OAI: diva2:581418


Available from: 2013-01-02 Created: 2013-01-02 Last updated: 2013-01-02Bibliographically approved
In thesis
1. Exploring phenomena that affect the fate and impact of radioactive materials in the blue mussel
Open this publication in new window or tab >>Exploring phenomena that affect the fate and impact of radioactive materials in the blue mussel
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Current protection of the marine environment from radiation is based largely on measuring, estimating and modelling accumulation and impact(s) of radionuclides in a few marine species. Using a relevant marine organism, this thesis focusses on investigating some poorly described phenomena that could cause deviations from predicted measurements.

Paper I investigated the biological transformation of tritium (radioactive hydrogen) into an organic compound. The resulting organically bound tritium (OBT) showed increased accumulation in mussels, unique incorporation into a key biological molecule (DNA), extended persistence in tissues, and greater toxicity than the inorganic form. Paper II demonstrated significant disparity in OBT accumulation between functionally similar microalgae species and that OBT in algae is readily transferred to a consumer.

Highly radioactive particles are a complex issue in radioecology due to their concentrated dose geometry, potentially inducing very different impacts in organisms, compared to external irradiation. Paper III developed a method to introduce radioactive particles that would facilitate their recovery, improve dose-calculation, and aid the measurement of toxicological endpoints. It also showed that such particles can be incorporated into mussel tissues, causing significant effects.

In Paper IV, hypoxia – another major ecological hazard in the marine environment – was expected to reduce radiosensitivity. The minimal observable effect from radiation prevented identification of such an interaction, and indicates drawbacks in the (otherwise sensitive) endpoints used. It appears that stressors like hypoxia may be more of a health hazard to marine organisms than environmental levels of ionising radiation.

By understanding such causes of variation in accumulation and impact, it is possible to improve risk assessment, providing more justification for regulations chosen and minimising conservatism in setting environmental standards.

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2013. 93 p.
Radioecology, ionising radiation, environmental protection, Mytilus edulis, bioaccumulation, dose-response, ecotoxicology, tritium, particle, hypoxia
National Category
Biological Systematics
Research subject
Marine Ecotoxicology
urn:nbn:se:su:diva-83404 (URN)978-91-7447-616-3 (ISBN)
Public defence
2013-01-18, DeGeersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)

At the time of doctoral defense, the following papers were not published and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2012-12-27 Created: 2012-12-10 Last updated: 2013-01-02Bibliographically approved

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Jaeschke, Benedict C.Bradshaw, Clare
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