ABSTRACT
In oligotrophic lakes with low nutrient concentrations, primary production is low, hypolimnetic oxygen concentration is generally high, and a large fraction of the settled phosphorus (P) is permanently buried in the sediments. Different responses were observed depending on whether cores were fed with trapped sediment material and whether the overlying water was oxic or anoxic. Sediment cores were taken at the deepest part of the lake and sliced immediately after sampling. Worldwide, many lakes are eutrophic or are becoming eutrophic because of excessive inputs of P. Thus, P is without doubt a pollutant of aquatic ecosystems, and a considerable amount of money is presently being spent to restore eutrophic lakes. The P content of a lake depends on: its external P loading, its P export via the effluent, the P sedimentation, and the P release from its sediment.
