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INTRODUCTION
All fate and effects studies of oil spills in the marine environment
depend on analytical chemical information concerning the distribution
and composition of the spilled oil. This includes petroleum
hydrocarbon concentrations and compositions in water, sediment, and
tissue samples. In turn, this information can be used to deduce the
nature of the weathering process (including evaporation, dissolution,
and biodegradation) , biological assimilation and depuration, and the
mass budget of the oil. Thus the analytical chemistry component of the
AMOCO CADIZ research program provides crucial information to many
other components of the program in the investigation of the timedependent
fate and effects of this spill.
During the six weeks following the grounding of the supertanker
AMOCO CADIZ on March 16, 1978, oil came ashore along 320 kilometers of
the Brittany coastline (Gundlach and Hayes, 1978). Various shoreline
types were impacted (e.g., rocky shores, sand flats, coastal embayments,
tidal mud flats and salt marshes). During the early stages of
the spill, oil was transported offshore and deposited in the benthic
environment. The fate of petroleum residues deposited in these impacted
areas was and continues to be affected by coastal processes which
dictate such factors as wave energy and sediment transport, and create
environments of differing substrate character (e.g., grain size),
chemical status (oxidizing versus reducing) , and biological activity
. All of these factors and others
(e.g., microbiological biomass)
(e.g., light intensity) combine to determine the weathering characteristics
of the residual petroleum assemblage.
Biological populations initially impacted by the spilled oil may
be subject to chronic exposure to petroleum hydrocarbons associated
with (and released from) the substrate to which they are closely
linked, or they may undergo rapid or slow depuration of initial residues
if no longer exposed to oil, via transplantation or due to flushing
by "clean" seawater. Such differential exposure histories have
been previously observed to profoundly affect the spilled oil residual
body burdens in marine organisms (Boehm et al., 1982).
Although oil spills have received increasing attention from the
scientific community during the past decade, there have been few
opportunities to examine the chemical compositional changes in beached
or sedimented oil in a variety of coastal environments, over a significant
period of time and to examine uptake (impact) and depuration
(recovery) of petroleum by marine organisms. A detailed examination of
the chemical changes in oiled substrate suggests both the anticipated
residence time of deposited oil, and the potential for biological
damage of the petroleum residues. Rashid (1974) examined compositional
changes of Bunker C oil from the ARROW spill in Nova Scotia at different
coastal locations. Other than this study only site-specific
studies of the geochemistry of petroleum weathering (e.g., Mayo et al.,
1978; Blumer et al., 1973; Teal et al . , 1978) have been undertaken.
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