Influence of liming on metal burdens in lake sediments

Abstract
During the last three decades, liming has been used as a large-scale treatment of acidified lakes in Sweden. Since the mobility of many metals decrease with increasing pH of the water, application of lime directly into the lake might increase metal deposition to the sediments. The aim of this project is to investigate the difference in metal deposition to the sediments in limed and non-limed lakes. Surface sediments from 11 limed and 10 non-limed lakes were collected during the summers of 1998 and 1999 and analysed for a number of elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, P, Pb, V and Zn). With reference to treatment method or acidification status, the lakes were divided into four sub-groups and the weighted mean areal metal burdens were statistically compared. Generally, the highest metal burdens were found in the surface limed group and the lowest burdens were found in the acidified reference group. Potential factors influencing the metal deposition were also evaluated by a multivariate analysis (PLS). The PLS indicated that liming is an important factor for the deposition of metals to lake sediments.