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Workreport 2017-15



Studies on Reference Mires: 2. Lastensuo, Pesänsuo and Häädetkeidas in 2010-2015


Aro, L., Korpela, V., Salemaa, M., Saarinen, M., Lahdenperä, A., Parviainen, L., Kuusisto, J.



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This report extends the understanding of mires in the biosphere site description and provide data for a range of modelling purposes. The post-glacial crustal rebound shapes the landscape from Finnish coastal areas to an inland type within a few millennia in the future. The properties of the future mire ecosystems surrounding the Olkiluoto Island can be forecast and radionuclide transport models applied based on the properties of present mires. Currently, however, there are no well-developed mires on the island. Due to the lack of Olkiluoto specific data, three mires, Lastensuo, Pesänsuo and Häädetkeidas, being in different successional stages were selected from the larger geographical Reference area as analogues of those expected to be formed at the Olkiluoto site.

In total, 18 plots were studied on three mires where site types varied from treeless hummock–hollow pine bog (KeR, stand volume 0.06 m3/ha) to Vaccinium myrtillus spruce swamp (MK, 432 m3/ha). Tree stand biomass varied from 14 to 28.5 g/m2 (fine roots excluded). Based on vegetation survey, the studied reference mires represented well mires typical for southwestern Finland, and the description of mires and occurred plant species were in line with those presented in literature. Depending on site type, reference mire and applied biomass functions, aboveground biomass of understorey vegetation was 56-282 g m-2 in the field layer and 35-332 g m-2 in the bottom layer of the reference mires. Tree nutrition was in balance. There was large variation in key element (Ag, Cl, Cs, I, Mo, Nb, Ni, Pb, Pd, Se, Sn and Sr) concentrations between plant species and mires. Very high concentrations of Cl was measured from cloudberry compared to other species on all reference mires

High variation of main nutrient contents in the surface peat layers (0-30 cm) revealed the diverse ecological conditions which are typical of mires due to variation in the thickness of peat layer, hydrology, vegetation, physical properties of peat and the stratigraphical history of the peat layer. Concentration ratios were calculated as a ratio of the concentration of an element in different plant species and compartments to that in its living environment, i.e. a 30-cm-thick peat soil in this report.

Altogether seventeen deep peat profiles were sampled. The bottom of the peat profiles was clay, sand or gyttja, indicating isolation contact. The depth of the peat profiles varied from 50 to 550 cm, the thinnest peat layers were in the Häädetkeidas mire. From the deep peat profile samples, porewater, bioavailable and total concentrations of the elements were analysed. In addition, environmental parameters (e.g. pH, LOI, clay and silt fraction, total C), specific to the soil type and elements were measured. The bioavailable and total in situ Kd values of the key elements Ag, Cl, Cs, I, Mo, Nb, Ni, Pb, Pd, Se, Sn and Sr were calculated. The Kd data of the peat samples were inherently extremely variable, but it also varied systematically with key environmental factors. Organic matter content and mineral composition, especially clay and silt fraction, have a distinct influence on the Kd values.


Biomass, berries, distribution coefficients (Kd values), geochemical and physical properties, elemental concentrations, ground vegetation, mushrooms, peat profile, plant dimensions, stand volume, surface peat, vertical root distribution


WR 2017-15_web (pdf) (10.4 MB)
Appendix 2_Results from chemical analyses of plant material (xlsx) (177.8 KB)
Appendix 3_Total elements in surface peat of Lastensuo (xlsx) (39.5 KB)
Appendix 4_Bioavailable elements in surface peat of Lastensuo (xlsx) (35 KB)
Appendix 5_CEC BS_Lastensuo (xlsx) (17.5 KB)
Appendix 6_Lastensuo porewater (xlsx) (40.1 KB)
Appendix 7_Lastensuo bioavailable concentrations (xlsx) (47.9 KB)
Appendix 8_Lastensuo total concentrations in deep peat profiles (xlsx) (46.9 KB)
Appendix 10_Total elements in surface peat of Pesänsuo (xlsx) (23.5 KB)
Appendix 11_Bioavailable elements in surface peat of Pesänsuo (xlsx) (21.4 KB)
Appendix 12_CEC BS_Pesänsuo (xlsx) (15.1 KB)
Appendix 13_Pesänsuo porewater (xlsx) (39.2 KB)
Appendix 14 Pesänsuo bioavailable concentrations in deep peat profiles (xlsx) (39 KB)
Appendix 15_Pesänsuo total concentrations in deep peat profiles (xlsx) (41.2 KB)
Appendix 17_Total elements in surface peat of Häädetkeidas (xlsx) (33.8 KB)
Appendix 18_Bioavailable elements in surface peat of Häädetkeidas (xlsx) (31.9 KB)
Appendix 19_CEC BS_Häädetkeidas (xlsx) (25.5 KB)
Appendix 20_Häädetkeidas porewater concentrations (xlsx) (55.6 KB)
Appendix 21_Häädetkeidas bioavailable concentrations in deep peat profiles (xlsx) (41.1 KB)
Appendix 22_Häädetkeidas total concentrations in deep peat profiles (xlsx) (47.5 KB)
Appendix 24 Concentration ratios for key elements (xlsx) (82 KB)


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