The effect of ageing on the toxicity of zinc for the potworm Enchytraeus albidus

Different extractable zinc fractions and the ecotoxicity of zinc in Enchytraeus albidus were assessed using freshly spiked artificial soils and spiked soils which had been aged for 8 weeks. Standard artificial Organization for Economic Cooperation and Development (OECD)-soils were aged in four different ways: (1) storing at 20°C; (2) percolation followed by storing at 20°C; (3) alternately heating at 60°C and storing at 20°C; and (4) alternately freezing at −20°C and storing at 20°C. Ageing had no clear influence on the pore water concentration, the water soluble and the calcium chloride extractable fraction of zinc in the artificial soils. Similarly, the 21d LC50 and the 42d EC50reproduction for E. albidus were not influenced by the different treatments. This absence of zinc fixation in the artificial soil during ageing was probably due to the use of kaolinite clay in OECD-soil.