The "equilibrium partitioning theory" is one of the most widely used models to evaluate the
bioavailability of sediment-associated, nonpolar, organic contaminants and it makes
specific assumptions regarding the factors that influence this bioavailability. The objective
of this research was to test two assumptions of this theory: (1) that benthic organisms are
exposed to a constant, equilibrium-predicted concentration of a contaminant in interstitial
water, regardless of the behavior of the organism; and (2) that exposure to interstitial water
in a sediment exposure system is equivalent to the exposure in a water-only exposure
system. The effect of behavior on the exposure to sediment-associated phenanthrene was
tested by exposing three marine amphipod species (with different burrowing behaviors) to
the polycyclic aromatic hydrocarbon (PAH) phenanthrene under two exposure conditions,
one with spiked sediment and clean overlying water and the other with spiked sediment and
contaminated overlying water. This was done to evaluate the extent to which the burrow
irrigating behavior and the different tube or burrow building behavior exhibited by the
amphipod species could effect the accumulation of sediment-associated phenanthrene. The
assumption of equivalent exposure between sediment and water systems was tested by
exposing the amphipods to the same concentration of phenanthrene in a water-only versus
sediment exposure system. In both series of experiments, the bioaccumulation of
phenanthrene by the amphipods was followed over 72 hours and bioaccumulation kinetics
calculated for each species and exposure treatment. The results indicated that the burrow
irrigating behavior of benthic marine amphipods can significantly affect the exposure of
these amphipods to sediment-associated contaminants by diluting the concentration of
contaminant in the interstitial water surrounding the organisms with overlying water.
Additionally, there was a species dependent decrease in exposure based upon the tube or
burrow building strategy used by the amphipod species. The results also indicated that
exposure in a sediment system was not equivalent to exposure in a water-only system. The
bioaccumulation of phenanthrene was significantly higher for all three species in water
versus sediment. However, the interpretation of the results from this second series of
experiments was complicated by the degradation of phenanthrene in the sediment-only
exposure. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28900 |
| Date | 30 May 1997 |
| Creators | Fuji, Takashi, 1961- |
| Contributors | Weber, Lavern J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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