Aro, Lasse

Ikonen, Ari

Mustonen, Joni

Jukuri

Problems in estimating radionuclide parameters in relation to nuclear waste disposal, long-term environmental change and mire succession

Ikonen, Ari T. K.

Problems in estimating radionuclide parameters in relation to nuclear waste disposal, long-term environmental change and mire successionLasse Aro*, Ari T. K. Ikonen**, Joni Mustonen***Tree foliage 1.622Living branches 2.438Dead branches 0.237Stem wood 1.612Stem bark 0.484Tree roots and stumps 2.029Understorey vegetation 0.414Acrotelm 245Catotelm 571Mineral subsoil (30 cm) 445Tree foliage 5.124Living branches 0.417Dead branches 0.053Stem wood 0.251Stem bark 0.190Tree roots and stumps 0.349Understorey vegetation 0.143Acrotelm 933Catotelm 0Mineral subsoil (30 cm) 445Tree foliage 0.000Living branches 0.001Dead branches 0.000Stem wood 0.001Stem bark 0.000Tree roots and stumps 0.000Understorey vegetation 5.585Acrotelm 23Catotelm 1442Mineral subsoil (30 cm) 445Background• Coastal areas of the Baltic Sea have been selected for nuclear waste repository sites in Finland and Sweden• Safety cases demonstrating the long-term safety of the repositories need to consider the ecosystems in a time frame of at least 10 – 100 thousand years• In these time frames, the post-glacial crustal uplift (at present 6 – 8 mm/y) change the landscape at the sites into an inland type and also mires will form• In addition to the formation of the mires, also their further development needs to be consideredRadioecological and radiological assessments• Radionuclide transport models that are simplified from conceptual and numerical hydrobiogeochemical models are used for the safety cases• The future ecosystems are projected from the past development in the region• Due to the long time frames, input data representing a limited set of mire types and characteristics are needed• For the repositories, radiologically most important radio-nuclides are long-lived but have very low or non-existing concentrations in the present environment – stable isotopes of the same elements are used as [biogeochemical] analogues• In this presentation the process of the input data derivation is exemplified with stable Ni (for Ni-59) in mires at different stages of developmentResults• No essential differences in Ni storage of vegetation between different mire stages (total Ni pool from A to C 8.8, 6.5 and 5.6 mg m-2, respectively)• Ni pool in vegetation is small compared to soil• Properties of the mineral subsoil (top layer 0 – 30 cm) are assumed to be the sameHow to combine data to represent one mire biotope in the biosphere assessment?• Using weighting factors based on aerial distribution of mires in different developmental stages in large mires (e.g. Lastensuo mire in western Finland, 440 ha with a catchment of 11 km2)• Using weighting factors based on biomass distribution in the same area?Fig. 1. Distribution of nickel (mg m-2) in forested mires (A; Posiva’s case), in a shallow peaty hardwood swamp (B; dominated by 20-year-old downy birches, peat thickness 0.23 m), and in a treeless bog (C; Lastensuo mire, peat thickness 6 m) in western Finland. Photos: Lasse Aro/Luke.ABCContact *	 Natural	Resources	Institute	Finland,	Parkano,	Finland,	lasse.aro@luke.fi**	 Environmental	Research	and	Assessment	EnviroCase	Ltd.,		 Pori,	Finland,	ari.ikonen@envirocase.fi***	Environmental	Research	and	Assessment	EnviroCase	Ltd.,		 Pori,	Finland,	joni.mustonen@envirocase.fi

Problems in estimating radionuclide parameters in relation to nuclear waste disposal, long-term environmental change and mire succession

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