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Th e River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand fi lters (F1, F2, and F3), established within or on the edge of the buff er zones. Th e fi lters contain burnt lime (CaO) or spent lime [CaO, Ca(OH) 2 , and CaCO 3 ]. Easily soluble lime results in a high pH level (>11) and leads to an effi cient precipitation of soluble phosphorus (P) from the runoff . Water samples were taken from the infl ow and outfl ow of each site in diff erent hydrological situations. Th e length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 signifi cantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. Th e proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both fi lter parts removed PTOT and SS effi ciently from the water; the burnt-lime part also removed DRP. Th e mixed-lime part removed DRP for a year, but then the effi ciency decreased. Th e eff ect of fi lters on nitrogen compounds varied. We conclude that sand fi lters incorporating lime can be used together with buff er zones to reduce both P and SS load to watercourses.

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Abstract. In Finland, Olkiluoto Island on the western coast has been selected as a repository site for spent nuclear fuel. Due to the shallow sea areas around the island, the postglacial land uplift is going to change the landscape within the next millennia. For instance, new lakes and mires will develop on the present offshore areas. Concerning radionuclide transport models, the properties of the future ecosystems surrounding Olkiluoto Island can be forecast based on the properties of present lakes and mires. Due to the lack of site-specific data, lakes and mires of various successional stages were selected within a larger geographical area as analogues of the future ones. Here we present an example of a systematic process for selection of appropriate analogue sites.

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