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Keywords:

  • Bioavailability;
  • Collembolan;
  • Pesticide;
  • Pore water;
  • Springtail

Abstract

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