PM09 Sediment Quality Assessment Cases
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(PM137) Differences in bioaccumulation of sediment bound PAHs by marine clams and cockles.
Golding, L1, Ahrens, M1, Depree, C1, 1 National Institute of Water and Atmospheric research (NIWA), Hamilton, New Zealand
ABSTRACT- The bioavailability of polycyclic aromatic hydrocarbons (PAHs) from estuarine sediments to benthic invertebrates is influenced by factors such as the sediment organic carbon content and composition, as well as the respective exposure route, such as porewater or dietary uptake. For this reason, bioaccumulation of sediment-bound PAHs by benthic biota may be expected to vary even when normalising for sediment organic carbon content. The objective of this study was to compare PAH bioavailability of estuarine sediments possessing different PAH levels and organic carbon content to bivalves with different feeding modes. Sediments of varying organic carbon content (0.9 – 7 %) and PAH concentration (17 – 750 mg/kg) and contamination history were collected from 8 sites within New Zealand. At the same time, resident shellfish (the deposit-feeding clam Macomona liliana and the suspension-feeding cockle Austrovenus stutchburyi) occurring at the sites were collected for analysis of their tissue PAH content. Furthermore, laboratory-based feeding experiments were conducted with Macomona liliana, by exposing clams to the 8 sediments over 28 days. We determined the biota to sediment accumulation factor (BSAF) of PAHs in field-collected and laboratory-fed clam and cockles by relating lipid-normalised PAH concentrations in bivalve tissues to PAH concentrations of the 8 sediments normalised for organic carbon content. BSAFs differed markedly between suspension-feeding cockles and deposit-feeding clams, and strong deviations of BSAFs from the expected value of 1 indicated reduced PAH bioavailability at some sites.
Key words: bioavailability, PAH, shellfish, feeding modes