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(25-04) Toxicity of PAHs to springtails in relation to soil sorption, lipophilicity and water solubility. Sverdrup, Line Emilie*,1,2, Nielsen, Torben3, Krogh, Paul Henning4, 1 University of Oslo, Department of Biology, N-0316 Oslo, Norway2 Jordforsk - Centre for Soil and Environmental Research, N-1432 ABSTRACT- Toxicity of sixteen PAHs to the soil dwelling springtail Folsomia fimetaria was investigated using an agricultural soil type with an organic carbon content of 1.6 %. The results show that only PAHs with reported log Kow values ≤ 5.2 (i.e. naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, pyrene, fluoranthene) significantly affected the survival or reproduction of springtails. Threshold values (EC10-values) for the toxicity of the individual PAHs could be expressed as pore-water concentrations by the use of reported organic carbon normalised soil - pore-water partitioning coefficients (Koc-values). For the PAHs with a log Kow ≤ 5.2, toxicity significantly (r2=0.67; p=0.012; n=8) increased with increasing lipophilicity of the substances, suggesting a narcotic mode of toxic action for most substances. The following regression equation was obtained: EC10( Key words: polycyclic aromatic hydrocarbons, terrestrial ecotoxicity, quantitative structure activity relationships |
s, Norway3 Risų National Laboratory, DK 4000 Roskilde, Denmark4 National Environmental Research Institute, DK-8600 Silkeborg, Denmark
mol/L)= -1.00*log Kow+4.0. Using this quantitative structure activity relationship (QSAR) to calculate threshold values for the toxicity of the remaining, non-toxic substances (benz(a)anthracene, chrysene, benzo(b)-fluoranthene, benzo(k)fluoranthene, dibenz(a,h)anthracene, benzo(a)pyrene, perylene, indeno(1,2,3-cd)pyrene), the absence of toxicity could in most cases be explained by the limited water solubility of these substances, indicating that they do act by narcosis as the mode of toxic action and that their toxicity is governed by concentrations in the pore-water. The results provide important input to future model predictions of the ecological risk posed by PAH contaminated sites.