RELIMING AND REACIDIFICATION EFFECTS ON LAKEWATER, CHEMISTRY, PLANKTON AND MACROPHYTES

Long term liming and reacidification effects were studied in SW Sweden . This report is a concentrated summary. Lake liming reduces toxic lev els of Al, Cd and Zn so that pH-sensitive species can survive. But it mobilizes nutrients and causes internal eutrophication, which in shall ow lakes may give problems as macrophyte expansion. Reacidification ki lls much of the flora and fauna, that adapted during limed conditions. The reasons are lowered pH and toxic levels: Al 500 ug/l, Cd 0.4 ug/l and Zn 50 ug/l. Sediments are fragile and temporary refuges for metal s and nutrients. Conclusively, surface waters should be limed before t hey reach lakes.