Reliming and reacidification effects on lakewater

Long term liming and reacidification effects were studied in SW Sweden. This report is a concentrated summary. Lake liming reduces toxic levels of Al, Cd and Zn so that pH-sensitive species can survive. But it mobilizes nutrients and causes internal eutrophication, which in shallow lakes may give problems as macrophyte expansion. Reacidification kills much of the flora and fauna, that adapted during limed conditions. The reasons are lowered pH and toxic levels: Al 500 ug/1, Cd 0.4 ug/1 and Zn 50 ug/1. Sediments are fragile and temporary refuges for metals and nutrients. Conclusively, surface waters should be limed before they reach lakes.