Showing papers by "Dag Klaveness published in 1983"

Seasonal variation of cadmium toxicity toward the alga Selenastrum capricornutum Printz in two lakes with different humus content

Abstract: The alga Selenastrum capricornutum Printz is used to investigate the potential of natural lake water to reduce cadmium toxicity. The two lakes involved differ in trophic status and in concentration and composition of dissolved organic matter, one being a typical dystrophic bog lake, the other a less humus influenced, eutrophic lake. In the dystrophic lake, the toxic effect is determined mainly by the free cadmium activity. In the eutrophic, less humus influenced lake, however, the toxic effect shows considerable seasonal variations with a toxicity far exceeding what would be expected according to the estimated free ion activity during summer. It is hypothesized that qualitative changes in the composition of the dissolved organic matter during the production period are responsible for this effect.