Balanced Fates of Pyrene and 1-Hydroxypyrene in Snails, Ilyanassa Obsoleta, and Spiked Sediments

Abstract

Eastern mud snails were exposed to pyrene (PY) and 1-hydroxypyrene (PYOH) spiked individually in sediment. Animals were examined for the bioaccumulation of parent compound and the presence of biotransformation products in soft tissue extracts after 3 days of exposure. Single and double oxidation products along with sulphate conjugates were detected in animals from both exposures, with traces of mono-glucuronide. The major phase I and II products were 1-hydroxypyrene (PYOH) and pyrene-1- sulphate (PYOS). Biotransformation was more efficient at low levels of PY or PYOH exposure and bioaccumulation more substantial at higher dose. Phase I oxidation was more efficient in fall exposed snails and phase II conjugation in the summer. Stressed animals were seen in the fall and analyzed separately from healthy ones. Their level of abundant metabolites was thrice that of non-stressed snails. The present data can be compared to a published study where snails were exposed to spiked food that was consumed within minutes. In that earlier work, stressed snails were associated with five times the level of metabolites than unaffected animals. Therefore, a longer contaminants' uptake time led to observing a lower excess of metabolites in soft tissues of impacted snails. PYOH degraded more readily in the snails' native sediments than PY, with intermediates in the catabolism of the compound detectable in sediments 3 days after spiking the media. This study demonstrates the importance of investigating the balance of fates of PAC in biotic and abiotic compartments in order to understand the state of the environment.

Key Words:

• body burden
• bioaccumulation
• biotransformation
• oxy-PAH
• stress

ACKNOWLEDGMENTS

Funding was provided by the National Science and Engineering Research Council of Canada (JH) and by the Bedford Institute of Oceanography (JH) of the Department of Fisheries and Oceans. We would like to thank other members of the Hellou group who helped to collect and maintain snails in our fisheries laboratory. We also acknowledge the support of Dalhousie University to the students (DGB, SE, SAM and LS). We are grateful for the analyses of toal, organic and inorganic carbons that were performed by Bill Leblanc in Michael Parsons group at Natural Resources Canada, BIO.

Notes

*TC stands for total carbon, TOC for total organic carbon and TIC for total inorganic carbon. Values are expressed in terms of dry weight.

*C refers to control animals, h and d represent healthy and distressed snails, and T stands for trace.