The effects of lime treatment in acidified lakes on sedimentP sorption and productivity

Abstract

In the last century fossil fuel combustion has resulted in acidification and elevated metalcontent in Swedish lakes. To counteract anthropogenic acidification, Sweden began a fullscale liming treatment program in the mid 1970’s. Even though the pH in lime treated lakesincreases after treatment, lake productivity does not always recover. The hypothesis of thisstudy was that increased metal input to the sediment decreases available phosphorus (P) in thewater. In this study, sediment cores were taken from three different types of lakes: limed,limed with fertilizer (added P), and acid (reference) lakes in southwest Sweden to investigatethe possible link between low production (P availability) and sediment metal content inacidified and limed lakes. Sediment was investigated for metal content and experimentalphosphorus (P) additions were conducted to determine P sorption characteristics. Lowequilibrium P concentration and high maximum P sorption in the experiments indicates thatthe sediment will adsorb P from the water column making the already nutrition pore waterless productive, driven mainly by high concentrations of aluminium and iron in sedimentlayers effected by both acidification and lime treatment. There were also indications that limeaddition will elevate P sorbing metals in the sediment of acidified lakes, which can lead toless P in the water column. Perhaps making modification (i.e. P addition) to the treatmentmethod is important for success in restoring acidified lakes