Abstract
Addition of limestone (liming) is the primary method used for restoring water chemistry in acidified lakes. Most studies have shown, however, that biological diversity and productivity do not return to pre-acidified conditions. Acidification alters phosphorus (P) cycling in lakes via increased input of P-binding metals (Fe and Al) from the watershed, increasing the burial and permanent removal of P from the system. Liming likely exacerbates P immobilization by enhancing conditions for precipitation of metal inputs and by adding P-binding metals contained in limestone (Al and Ca) to lakes. The reduction in P availability (oligotrophication) and extent to which this process may limit biological recovery is currently unknown. The proposed research will quantify the immobilization of P by excess metal inputs in limed lakes. Associated changes in P cycling between lake water and sediment will also be determined through a series of laboratory experiments. The ensemble of empirical data will be used to construct a mechanistic sediment P diagenesis model that can predict the effect of liming on P availability in lakes. Model output will be linked to biological data in the study lakes to determine how liming affects biological diversity and productivity. The proposed research will provide a multidisciplinary link between chemistry and biology and lead to improved methods for biological recovery in limed lakes.
Sweden