Effects of single Ca(OH)(2) doses on phosphorus concentration and macrophyte biomass of two boreal eutrophic lakes over 2 years

Two hardwater eutrophic lakes of central Alberta were subjected to single doses of Ca(OH) (74 or 107 mg L super(-1)). The effects of lime treatment on phosphorus (P) precipitation, sediment P release, and macrophyte biomass were assessed for up to 2 years. In both lakes, sediment P release was reduced to 16 and 27%, respectively, of pre-treatment values by the first winter following treatment. However, sediment P release returned to pre-treatment values during the following year. In contrast to these short-term effects, macrophyte biomass decreased by as much as 80% after lime application and remained there for at least 2 years. Our results indicate that a single dose of Ca(OH) may give short-term (< 1 year) control of P and long-term control (> 1 year) of macrophytes in hardwater eutrophic lakes of Alberta.