Influence of Soil Type and Organic Matter Content on the Bioavailability, Accumulation, and Toxicity of Α‐cypermethrin in the Springtail Folsomia Candida

The influence of organic matter (OM) content on α‐cypermethrin porewater concentrations and springtail Folsomia candida accumulation was investigated in two soils with different levels of organic matter, a forest soil with a total organic carbon (TOC) content of 5.0% (OM = 11.5%) and an agricultural soil with a TOC content of 1.3% (OM = 4.0%). Also, the effects of α‐cypermethrin concentrations in soil and pore water and the influence of soil aging on springtail reproduction were investigated. Springtail reproduction was severely affected by increasing α‐cypermethrin in soil with 1.3% TOC; the median effective concentration value (EC50) was estimated to 23.4 mg/kg (dry wt). Reproduction was only marginally affected in the soil with 5.0% TOC, and no EC50 value could be estimated. However, when expressing α‐cypermethrin accumulation as a function of soil α‐cypermethrin concentrations, no difference was found between the two soil types, and no additional α‐cypermethrin uptake was observed at soil concentrations above approximately 200 mg/kg (dry wt). By using solid‐phase microextraction (SPME), it could be demonstrated that α‐cypermethrin porewater concentrations were higher in the soil with low organic matter (LOM) content than in the soil with high organic matter (HOM) content. Furthermore, a clear relationship was found between α‐cypermethrin concentrations in springtails and porewater. Soil aging was not found to exert any effect on α‐cypermethrin toxicity toward springtails. The study indicates that the springtail's accumulation of α‐cypermethrin and reproduction is governed by α‐cypermethrin porewater concentrations rather than the total α‐cypermethrin concentration in soil. Environ. Toxicol. Chem. 2010;29:1084–1090. © 2010 SETAC