THESIS APPROVAL

(1997) said that naphthalene is moderately hydrophobic with log Kow of 3.34, and
this chemical may thus have a tendency to adsorb to particulate matter and
accumulate in biota if the period of exposure is no longer. From these documents, it
is suggested that naphthalene body burden may depends on the period of time
exposure. With an estimation by 96 h test period using in this study, it could be said
that naphthalene remained in the test sediment tends to transfer and then
bioaccumulate in the tissue of L. hoffmeisteri.
105
The route of uptake of a chemical to an organism will have a major
influence on the bioaccumulation of many chemical contaminants. Aquatic animals
may be exposed to such contaminants via several routes, such as, the food by
ingestion, through the overlying water, by pore water, by the respiratory system, and
by dermal absorption. The latter two routes of entry is called skin absorption for
some invertebrate species which do not have very specialized respiratory organs
(Conrad et al., 2002). James and Kleinow (1994) stated that the different uptake route
would affect bioaccumulation. Several previous studies have suggested that pore
water is the most important route of uptake for infaunal benthic organisms, including
oligochaetes (Roesijadi et al., 1978a; Oliver, 1984; Knezovich and Harrison, 1988).
The chemical was accumulated via pore water or via direct contact of integument with
sediment particles and then entered to the body of oligochaetes (Leppanen and
Kukkonen, 1998b). Although these animals received their body burden both through
interstitial water and sediment ingestion, the low molecular weight PAHs, such as
naphthalene (128.18), is more available to such organisms that mainly accumulate
from pore water due to only 2-ring PAH with hydrophilic character. This is agreed
with the work of Lyes (1979), Landrum (1989), Weston (1990) and Meador et al.
(1995). In comparison with highly hydrophobic PAHs, strongly associated with
particulate matter are accumulated in deposit-feeder as a result of sediment ingestion
(Lyes, 1979; Landrum, 1989; Boese et al., 1990; Schrap and Opperhuizen, 1990;
Weston, 1990; Meador et al., 1995). Chemicals with greater hydrophobicity are more
tightly associated to solids which in turn increase the importance of ingested material
in accumulation (Leppanen and Kukkonen, 2000a). This is in agreement to previous
studies conducted with other oligochaete species. Leppanen and Kukkonen (1998b)