Evaluation of Daphniamagna for the Ecotoxicity Assessment of Alkali Leachate from Concrete

Abstract

The cladoceran Daphniamagna has been used as an aquatic test species in aquatictoxicology. To evaluate the aquatic toxicity of leachate from concrete, the immobilization ofD. magna was observed after treatment of various concentrations of leachate specimens. Reliabilities of the culture condition and the experimental protocol for acute toxicity test weresuccessfully achieved from the standard toxicity test. The leachates were prepared from themixture of Ordinary Portland Cement (OPC) and pozzolanic admixtures, Pulverised fuel ash(PFA), Ground granulated blast furnace slag (GGBS) and GGBS containing loess. Acutetoxicity test showed 100% immobilization of D. magna for OPC or PFA. The leachates fromOPC or PFA had high pH 10 to 12. However, GGBS and GGBS containing loess showedless toxicity according to the concentrations. Especially, immobilization was not observed atthe concentrations below 12.5% of GGBS containing loess. Also the range of pH for thesespecimens was 8 to 9. This suggested that the use of loess as the admixture in concretemay be useful to reduce eco-toxicity of leachates from concrete. This our study provided theharmfulness of the alkali leaching from concrete in aquatic environment and the usefulness ofD. magna to evaluate the toxicity of leachates from concrete.