Olkiluoto Biosphere Description 2006 (pdf) (4.1 MB) - Posiva

30Al mg/kg in C needles of spruce50454035302520151050MRK5 MRK6 MRK8 FIP102003: No wash2004: No wash2003: Chloroformwash2004: ChloroformwashFigure 4-2. Aluminium in current spruce needles in MRK plots (Fig. A-2). MRK5 islocated closest to the rock piling and crushing area, FIP10 is the farthest (Haapanen2006).Radionuclides and Stable IsotopesThe company operating the nuclear power plant, TVO, has monitored radioactivity inthe environment since the 1970s. Radionuclide concentrations in direct wet depositionat Olkiluoto over recent years have been low; however, some traces of ChernobylderivedCs-137 are still detectable (Ikonen 2003, Roivainen 2005, Haapanen 2005,2006).On the basis of sampling in 1989-1995, the isotopic contents of H-2 and O-18 ofprecipitation display some seasonal variation, both being lower in winter than in thesummer. For example, the range of 18 O c of annual precipitation has been –17‰ to –8‰ snow to rain (Posiva 2003, p. 153). A three-year sampling programme for theseisotopes in precipitation and in shallow groundwater was launched in January 2005,supported by the deposition monitoring network (MRK).4.3 Past Climate and VegetationPast Climate StagesIn Finland, glaciations have occurred periodically for at least the last 900,000 years(900 ky; Anttila et al. 1999). There is clear evidence that the timing and extent ofglaciations are largely dependent on small periodic changes in the orbit of the Eartharound the Sun resulting in changes in the solar radiation on the Earth. This is known asthe Milankovitch Theory (Forsström 1999). Occurrence of permafrost is also dependenton climate conditions as discussed by Ahonen et al. (2002) and Gascoyne (2000).c Position of stable isotope composition relative to the global meteoric waterline (GMWL) indicatespotential chemical and physical conditions and processes, and it is usually measured bycomparing the sample to the standard mean ocean water (per mille of SMOW, denoted with ).