Ecotoxicity of cobalt to the springtail Folsomia candida

Despite growing concern about the potential adverse effects of elevated cobalt concentrations in the environment, hardly any toxicity data are available for terrestrial invertebrates. Therefore, chronic toxicity of cobalt was assessed for the springtail Folsomia candida. The 28-day EC50 for the reproduction of F. candida was 1480 mg Co/kg dry wt in standard artificial soil (OECD) and 409 mg Co/kg dry wt in standard field soil (LUFA 2.2). The difference in toxicity can be explained by the higher pH and cation exchange capacity which decreased cobalt bioavailability in the OECD soil. When expressed as pore water concentrations, 28-day EC50s were similar: 159 mg Co/L in OECD and 174 mg Co/L in LUFA 2.2, which corresponded with calculated Co2+ activities of 0.953 and 1.20 mmol/L, respectively. Although the presented data can be considered as a step forward in the assessment of the potential risk of cobalt in the terrestrial environment, more toxicity data for different species are needed to evaluate the environmental risk of cobalt in soils.