Use of Selenastrum Capricornutum Growth Inhibition Test for Testing Toxicity of Metal Ions in Soil and Water

Abstract

The unicellular green alga Selenastrum capricornutum (Rhapidocelis subcapitata) growth inhibition assay was applied to the toxicity testing of water, suspensions of heavy-metal-polluted clinker and waste ore pile. The ISO 8692:2004 standard test procedure was followed, and growth rate inhibition indexes were determined. Despite high concentrations of zinc in water (38.47 mg/L of Zn), exceeding by approximately 400-fold the EC50 value for S. capricornutum (0.1 mg Zn/L), 72-h algal growth in the soil extracts was inhibited with 50% in comparison with growth in the standard control ISO mineral medium. Cell dead of algae was observed by clinker leacheates contained up to 796 mg Cu/L. Decreasing of inhibition effect and rate of cell dead could not be explained by supplementary nitrogen, phosphorous, and carbonate leached from the waste ore pile and clinker.