of oil rarely occurs under anaerobic conditions. After all, fossil deposits survived for
millions of years under anaerobic conditions.
8000 t of heavy fuel oil was spilled, and covered 300 km of the coast of Chedabucto
Bay in Nova Scotia, Canada, when the tanker "Arrow" went agorund in 1970. Five
years later, oil was still traceable in the sediment. Since oil streams out of the sediment into the adjacent shallow areas at low tides, animal life in the shallows is still
affected by it. The prediction is that it will be more than 150 years before this oil has
disappeared (Fig. 51; Vandermeulen and Gordon 1976).
i) Persistence and Wide Ranging Ocean Distribution: Hydrocarbons with many carbon atoms, particularly cycloalkanes and aromatic compounds, hardly evaporate, are
insoluble in water, and are not usually biodegraded by organisms. Because of this, the
preconditions are met for these compounds to be perSistent, for holding them in the
environment of the ocean for a long time, and for their accumulation over the years
when the amount of added oil components outweights the amount of natural sedimentation. It is speculated that part of the oil components that during World War II
got into the Atlantic by torpedoed tankers is probably still present in the ocean, but
quantitative models are still lacking that would furnish information on whether the
concentration of persistent petroleum hydrocarbons is presently on the increase in
those seas with tanker traffic or whether the new regulations are causing a decrease
in oil pollution.
Aside from remote areas, for example the Beaufort Sea in the Canadian Arctic before
the oil boom, tar can be found floating on all the oceans of the world. In 1975, there
was 0.3 mg/m 2 in the North Sea (Oppenheimer et al. 1977), 10 mg/m 2 in the subtropical areas of the Atlantic, for example Sargasso Sea. The figure stands at up to
500 mg/m 2 for the Mediterranean. Perhaps 0.1 mg/m 2 is the figure for all the oceans
of the world. This means 36,000 t. Other estimates go up as high as 150,000 t. The
analyses of millimeter-sized to potatO-Sized tar balls drifting on the Atlantic Ocean
in the region of the Canary Islands provide hints that they derive from the washing
of tankers on their way back round the Cape of Good Hope (Ehrhardt and Derenbach
1977).
Hydrocarbon analyses in seawater are available for various ocean areas, but they are
difficult to compare because the results differ, depending on how the water samples
were analyzed. From ocean water that is not particularly polluted, 0.5--5 I1g/1 of
hydrocarbons have actually been extracted. There is some probability that in the
Atlantic Ocean and in the Pacific Ocean the average concentration is about 1.5 11g/1.
But hydrocarbons analyzed are a mixture of petroleum and biogenic compounds, and
the water samples have not been filtered, so that part of the hydrocarbons may occur
in particulate form (Brown and Searl 1977).
It has not been explained up till now what percentage of these hydrocarbon amounts
is traceable to marine pollution by petroleum. Petroleum is a product of nature which
came into being during the geological past. Petroleum components, also, are not
unknown to recent vegetation. It is certain that many organic compounds contained
in petroleum are continuously being formed by organisms living today. This is the
case with land vegetation, in particular where forests of conifers give off large quantities of volatile terpenes into the atmosphere. Likewise in forest fires, numerous
78
millions of years under anaerobic conditions.
8000 t of heavy fuel oil was spilled, and covered 300 km of the coast of Chedabucto
Bay in Nova Scotia, Canada, when the tanker "Arrow" went agorund in 1970. Five
years later, oil was still traceable in the sediment. Since oil streams out of the sediment into the adjacent shallow areas at low tides, animal life in the shallows is still
affected by it. The prediction is that it will be more than 150 years before this oil has
disappeared (Fig. 51; Vandermeulen and Gordon 1976).
i) Persistence and Wide Ranging Ocean Distribution: Hydrocarbons with many carbon atoms, particularly cycloalkanes and aromatic compounds, hardly evaporate, are
insoluble in water, and are not usually biodegraded by organisms. Because of this, the
preconditions are met for these compounds to be perSistent, for holding them in the
environment of the ocean for a long time, and for their accumulation over the years
when the amount of added oil components outweights the amount of natural sedimentation. It is speculated that part of the oil components that during World War II
got into the Atlantic by torpedoed tankers is probably still present in the ocean, but
quantitative models are still lacking that would furnish information on whether the
concentration of persistent petroleum hydrocarbons is presently on the increase in
those seas with tanker traffic or whether the new regulations are causing a decrease
in oil pollution.
Aside from remote areas, for example the Beaufort Sea in the Canadian Arctic before
the oil boom, tar can be found floating on all the oceans of the world. In 1975, there
was 0.3 mg/m 2 in the North Sea (Oppenheimer et al. 1977), 10 mg/m 2 in the subtropical areas of the Atlantic, for example Sargasso Sea. The figure stands at up to
500 mg/m 2 for the Mediterranean. Perhaps 0.1 mg/m 2 is the figure for all the oceans
of the world. This means 36,000 t. Other estimates go up as high as 150,000 t. The
analyses of millimeter-sized to potatO-Sized tar balls drifting on the Atlantic Ocean
in the region of the Canary Islands provide hints that they derive from the washing
of tankers on their way back round the Cape of Good Hope (Ehrhardt and Derenbach
1977).
Hydrocarbon analyses in seawater are available for various ocean areas, but they are
difficult to compare because the results differ, depending on how the water samples
were analyzed. From ocean water that is not particularly polluted, 0.5--5 I1g/1 of
hydrocarbons have actually been extracted. There is some probability that in the
Atlantic Ocean and in the Pacific Ocean the average concentration is about 1.5 11g/1.
But hydrocarbons analyzed are a mixture of petroleum and biogenic compounds, and
the water samples have not been filtered, so that part of the hydrocarbons may occur
in particulate form (Brown and Searl 1977).
It has not been explained up till now what percentage of these hydrocarbon amounts
is traceable to marine pollution by petroleum. Petroleum is a product of nature which
came into being during the geological past. Petroleum components, also, are not
unknown to recent vegetation. It is certain that many organic compounds contained
in petroleum are continuously being formed by organisms living today. This is the
case with land vegetation, in particular where forests of conifers give off large quantities of volatile terpenes into the atmosphere. Likewise in forest fires, numerous
78