Abstract
Effects of steel-making slag addition on growth of the diatom Skeletonema costatum and the dinoflagellate Alexandrium tamarense, which are common phytoplankton species in spring in Hiroshima Bay, were examined. While the growth of S. costatum was intensified optimally with addition of 100mg slag L-1, that of A. tamarense was depressed with addition of the slag in the range of 50-150mg L-1. From monitoring nutrient concentrations, it was clear that S. costatum utilized efficiently the nutrients dissolved from the slag. On the other hand, A. tamarense appeared to be too sensitive to pH increase by slag addition to grow. The different growth responses were discussed in terms of the carbonate-pH system. It is concluded that an application of steel-making slag can be a useful measure to remediate coastal marine ecosystems where Si and P are depleted if amount and timing of addition are well studied.
