Vol. 53 - Alaska Resources Library and Information Services

some of the oil during the period between the first and second post-spill sampling (about 2
weeks).
A different pattern of hydrocarbon bioaccumulation was evident in the two
deposit-feeding bivalves, Macoma calcarea and Nuculana minuta. In these species, uptake
of petroleum hydrocarbons in all four bays was more gradual and maximum body burdens
were reached in the second post-spill samples.
Although Bay 7 was considered a reference bay, 50-100 ppb dispersed and
soluble petroleum hydrocarbons were measured in the water column of the bay after the
dispersed oil spill. The benthic bivalves from this bay, in particular Serripes groenlandicus
and Mya truncata, became contaminated with petroleum hydrocarbons immediately after
the spill.
2.2.1. Mya truncata. The analytical results from 20 samples of Mya truncata
are summarized in Figures 2.2-2.15. Results correspond to one GC/MS/DS analysis of a
pooled extract of five stations along a depth stratum. For example, the 1-day post-spill
sample from Bay 9 (7m) represents a result of a pooling of five samples (1 sample = 10
animals) along the 7-meter depth stratum in this bay. Pre-spill, 1-day post-spill, and 2-
week post-spill analyses are presented for each bay. A set of samples from the inshore (3-
meter) transect was analyzed from Bays 9 and 10.
In addition to the pooled 5-station
sample, analyses were conducted on animals from two individual stations in Bay 9.
Total
petroleum (by UV) values for samples from each station and selected capillary GC traces
are presented as well.
There were differences in the patterns of accumulation of different aromatic
and sulfur heterocyclic hydrocarbons in M. truncata from different water depths in the
same bay (e.g., Figure 2.2) and from different stations along the same depth transect
(Figure 2.3), perhaps indicating an uneven distribution of hydrocarbons in the bays. In M.
truncata from Bays 9 and 10 which received dispersed oil, the compound accumulated to
the greatest extent from each of the three homologous series examined in detail was
C3-naphthalenes, C2-phenanthrenes and C2-dibenzothiophenes (Figures 2.2 and 2.7). Only
very small amounts of higher molecular weight polycyclic aromatic hydrocarbons were
accumulated ( [sigma] PAH in figures).
On the other hand, M. truncata from Bay 11 which
received undispersed oil, preferentially accumulated C4-naphthalenes, C 3 -phenanthrenes
and C3-dibenzothiophenes. These clams also accumulated proportionately much smaller
amounts of naphthalene and alkyl naphthalenes than did clams from Bays 9 and 10. M.
truncata from Bay 11 undoubtedly were exposed to more highly weathered oil than clams
in Bays 9 and 10.
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