Correlations of Eisenia fetida metabolic responses to extractable phenanthrene concentrations through time

Eisenia fetida earthworms were exposed to phenanthrene for thirty days to compare hydroxypropyl-beta-cyclodextrin (HPCD) extraction of soil and H-1 NMR earthworm metabolomics as indicators of bioavailability. The phenanthrene 28-d LC50 value was 750 mg/kg (632-891, 95% confidence intervals) for the peat soil tested. The initial phenanthrene concentration was 319 mg/kg, which biodegraded to 16 mg/kg within 15 days, at which time HPCD extraction suggested that phenanthrene was no longer bioavailable. Multivariate statistical analysis of H-1 NMR spectra for E. fetida tissue extracts indicated that phenanthrene exposed and control earthworms differed throughout the 30 day experiment despite the low phenanthrene concentrations present after 15 days. This metabolic response was better correlated to total phenanthrene concentrations (Q(2) = 0.59) than HPCD-extractable phenanthrene concentrations (Q(2) = 0.46) suggesting that H-1 NMR metabolomics offers considerable promise as a novel, molecular-level method to directly monitor the bioavailability of contaminants to earthworms in the environment. (C) 2010 Elsevier Ltd. All rights reserved.