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Workreport 2016-50

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Name:

Studies on the Aquatic Environment at Olkiluoto and Reference Area: 2. Reference Lakes in 2011–2012

Writer:

Kangasniemi, V., Ikonen, A., T., K., Mustonen, J.

Language:

English

Page count:

594

Summary:

This working report presents the results of Posiva’s sampling campaigns in Lakes Koskeljärvi, Lutanjärvi, Poosjärvi, Kivijärvi and Lampinjärvi, Finland, in 2011–2012. These so-called reference lakes are considered to resemble the aquatic systems expected to form at the Olkiluoto repository site due to the post-glacial land uplift in a time scale relevant to deep disposal of nuclear waste. The aim of the studies was to continue the sampling campaign started in 2010 in order to improve the knowledge of the lake ecosystems and to produce new input data to the modelling underpinning the repository safety cases. Surface water, sediment, macrophyte and fish samples were collected for biomass and dimension measurements and for analysis of their element composition. In addition, water-to-biota concentration ratios and element distribution coefficients (Kd) in the sediment were calculated.

In the field campaign, a main objective was to estimate the areal biomass distribution and measure the dimensions of both the characteristic aquatic plants and animals. Another main objective was to estimate the transfer of different indigenous elements, considered analogues for their long-lived radioisotopes in the safety case modelling, from the water to aquatic organisms, as well as to estimate their sorption into the surface sediment. The present contribution reports the materials, methods and results of the field and laboratory work, though, and the more detailed analysis and application of the data obtained is in the remit of further work. This report also extends and details the key results of the crayfish campaign at Lake Säkylän Pyhäjärvi, presented earlier in the 4th European Large Lakes Symposium (ELLS) held in August 2015 in Joensuu, Finland. In addition, this report presents related unpublished and corrected data from the 2010 sampling campaigns on the lakes, methods and results of a sediment sampling campaign at Lake Säkylän Pyhäjärvi in 2012, and the field survey to potential further lake and river sampling locations in 2012. All in all, the extensive dataset presented in this report considerably improves the database for site-specific biosphere assessments in safety cases for the Olkiluoto repository site.

Keywords:

Water quality; surface sediment; aquatic macrophytes; fish; signal crayfish; macrobenthos; biomass; body dimensions; element concentration; water-to-biota concentration ratio; solid/liquid distribution coefficient (Kd); biosphere assessment; safety case.

File(s):

Studies on the Aquatic Environment at Olkiluoto and Reference Area: 2. Reference Lakes in 2011–2012 (pdf) (36.4 MB)


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