download 21.6mb - Oil-Spill-Info.com

atio of more than 100 is an index of oil pollution in surface sediments
(Table 2). In this study, only four samples had a ratio less than 100;
80 percent of collected samples had a ratio more than 200; and 28
percent had a ratio more than 1,000. This simple parameter confirmed
that the surface sediments were highly contaminated.
Three sedimentary oil accumulation areas were recognized in the Bay
of Morlaix: the Morlaix River, the Penze River, and the east area of
the bay around Primel. In the Bay of Lannion, pollution was located
beyond a line joining Beg An Fry and the lie Grande marsh (Fig. 5)
. On
the whole, from July 1978 to February 1979, the decontamination process
was related to two essential factors: sediment type and the energy
level of the geographic zone. Among muddy and fine-grained sands, a
slow decrease in oil content was observed, whereas in areas more exposed
to high energy conditions, as around Primel in the eastern part of the
Bay of Morlaix, the fine- and coarse-grained sand bottom was rapidly
cleaned (Table 3) .
TABLE 2. Ratio of hydrocarbons/organic carbon (HC/OC) in unpolluted and
polluted surface sediments (from Marchand and Roucache, 1981) .
LOCATION