432
Hjalmar THIEL
been the recipient of all wastes produced on canoes,
rafts, sailing ships, steamers and ocean liners. Trawling
the bathyal or the abyssal seafloor recovers beer and
medicine bottles, cans, dishes, furniture parts, plastic
sheets, paint brushes, bricks and many other remains
of civilization (Galil et al., 1995). The most abundant
waste material, however, is clinker together with some
unburnt hard coal (Thiel, 1972). During the steamship
era thousands of tonnes of coal were burnt daily and
all the ashes and clinker were shovelled over the rail.
On the deep-sea floor the shipping routes are clearly
marked by this material, as today there are oil residues
and drifting tar lumps on the ocean surface (e.g.,
Day and Shaw, 1987; Golik et al., 1988) which may
eventually sink to the seafloor. In 1972 regulations
were adopted, the so-called London Convention (“LC”,
see p. 457), to prevent the pollution of the sea by
dumping of wastes produced on land but loaded on
board ships for disposal at sea. Whereas in 1979 an
estimated 17 million tonnes of industrial wastes were
dumped, the amount decreased to 6 million tonnes in
1987. Dumping of certain waste types in shallow waters
is still considered a practicable and environmentally
acceptable option, but the dumping of sewage sludge
decreased from 17 million tonnes in 1980 to 14 million tonnes in 1985, with further reductions in the
subsequent years (International Maritime Organization,
1991). Much of the material disposed of on the high
seas will eventually sink down to great depths.
The MARPOL (MARitime POLlution) 73/78 Convention of the International Maritime Organization (IMO)
regulates the discharge of residues from ships at
sea, tank washing etc. and transportation of goods,
including bulk chemicals and oil, to cover considerations of safety and pollution. Ports are required to
provide facilities to collect all wastes; but it remains
cheaper to dump at sea, and only signatory states are
bound by the IMO regulations. Consequently, much of
the waste accumulating during ship passages is still
discharged into the ocean surface, but glass bottles and
other rapidly sinking materials are now often released
after crushing into small particles, which again mark
the shipping routes along the seafloor. The amounts
secretly discharged at sea are not known and may
be high. Rumours in seamen’s circles suggest that
containers with unknown contents are often loosely
lashed in the top layer of freighters and might get lost
“occasionally” in stormy weather.
Wastes with hard surfaces arriving at the bottom of
the deep ocean may disappear in the soft ooze, but may
also extend into the near-bottom water and constitute
a hard substrate for colonization by sedentary species.
Regions which have been contaminated with high
amounts of hard-surface wastes, for instance below
the main shipping routes, may be expected to exhibit
secondary ecological impacts through alterations in
community structure. Since the average amount of
food for all the benthos remains the same over
geological time spans, an increase in hard substrate and
subsequently in sedentary fauna will inevitably result in
a decrease in the density of soft-bottom fauna due to
competition and changed energy partitioning.
Losses of ships at sea
With increasing traffic and tonnage, increased loss of
ships can be expected. Most wrecks are situated in
coastal regions, but many have sunk on the high sea to
great depth. Specifically, during World Wars I and II,
many warships and merchant ships were sent to the
deep-sea floor. In peace-times during the period from
1971 to 1990, according to Lloyd’s Register (1990,
1996), a total of 3701 ships comprising 12 861 975
gross tonnes were lost due to foundering, fire or
explosion, or went missing, not including shallowwater losses. If 10% of these ships are assumed to be
lost on the high seas, this would amount to an average
of 18 ships and 65 000 tonnes per year arriving on
the deep-sea floor. For 1996, corresponding figures are
11 ships and 47 000 tonnes.
Those ships were totally lost with all their equipment, installations, fuel and cargo, certainly including
poisonous and persistent substances. These potential
pollutants may be sealed off in the ships’ hulls,
but eventually, after decades, they may be released,
contaminating the nearby area or drifting away with
the currents, probably for long distances, and then
returning to the surface. The impact of wrecks on the
abyssal seafloor has never been investigated, although
modern techniques are suitable for studying their
effects. This is demonstrated by the discovery of the
Titanic, corroding away at a depth of 3800 m in the
Northwest Atlantic since 1912, and by the detection of
the Lucona at a depth of 4511 m in the Indian Ocean,
as part of the investigation of an insurance fraud since
1977 (Mullen, 1991).
Waste disposal in the deep ocean
The production of wastes in human societies is tremen-
Hjalmar THIEL
been the recipient of all wastes produced on canoes,
rafts, sailing ships, steamers and ocean liners. Trawling
the bathyal or the abyssal seafloor recovers beer and
medicine bottles, cans, dishes, furniture parts, plastic
sheets, paint brushes, bricks and many other remains
of civilization (Galil et al., 1995). The most abundant
waste material, however, is clinker together with some
unburnt hard coal (Thiel, 1972). During the steamship
era thousands of tonnes of coal were burnt daily and
all the ashes and clinker were shovelled over the rail.
On the deep-sea floor the shipping routes are clearly
marked by this material, as today there are oil residues
and drifting tar lumps on the ocean surface (e.g.,
Day and Shaw, 1987; Golik et al., 1988) which may
eventually sink to the seafloor. In 1972 regulations
were adopted, the so-called London Convention (“LC”,
see p. 457), to prevent the pollution of the sea by
dumping of wastes produced on land but loaded on
board ships for disposal at sea. Whereas in 1979 an
estimated 17 million tonnes of industrial wastes were
dumped, the amount decreased to 6 million tonnes in
1987. Dumping of certain waste types in shallow waters
is still considered a practicable and environmentally
acceptable option, but the dumping of sewage sludge
decreased from 17 million tonnes in 1980 to 14 million tonnes in 1985, with further reductions in the
subsequent years (International Maritime Organization,
1991). Much of the material disposed of on the high
seas will eventually sink down to great depths.
The MARPOL (MARitime POLlution) 73/78 Convention of the International Maritime Organization (IMO)
regulates the discharge of residues from ships at
sea, tank washing etc. and transportation of goods,
including bulk chemicals and oil, to cover considerations of safety and pollution. Ports are required to
provide facilities to collect all wastes; but it remains
cheaper to dump at sea, and only signatory states are
bound by the IMO regulations. Consequently, much of
the waste accumulating during ship passages is still
discharged into the ocean surface, but glass bottles and
other rapidly sinking materials are now often released
after crushing into small particles, which again mark
the shipping routes along the seafloor. The amounts
secretly discharged at sea are not known and may
be high. Rumours in seamen’s circles suggest that
containers with unknown contents are often loosely
lashed in the top layer of freighters and might get lost
“occasionally” in stormy weather.
Wastes with hard surfaces arriving at the bottom of
the deep ocean may disappear in the soft ooze, but may
also extend into the near-bottom water and constitute
a hard substrate for colonization by sedentary species.
Regions which have been contaminated with high
amounts of hard-surface wastes, for instance below
the main shipping routes, may be expected to exhibit
secondary ecological impacts through alterations in
community structure. Since the average amount of
food for all the benthos remains the same over
geological time spans, an increase in hard substrate and
subsequently in sedentary fauna will inevitably result in
a decrease in the density of soft-bottom fauna due to
competition and changed energy partitioning.
Losses of ships at sea
With increasing traffic and tonnage, increased loss of
ships can be expected. Most wrecks are situated in
coastal regions, but many have sunk on the high sea to
great depth. Specifically, during World Wars I and II,
many warships and merchant ships were sent to the
deep-sea floor. In peace-times during the period from
1971 to 1990, according to Lloyd’s Register (1990,
1996), a total of 3701 ships comprising 12 861 975
gross tonnes were lost due to foundering, fire or
explosion, or went missing, not including shallowwater losses. If 10% of these ships are assumed to be
lost on the high seas, this would amount to an average
of 18 ships and 65 000 tonnes per year arriving on
the deep-sea floor. For 1996, corresponding figures are
11 ships and 47 000 tonnes.
Those ships were totally lost with all their equipment, installations, fuel and cargo, certainly including
poisonous and persistent substances. These potential
pollutants may be sealed off in the ships’ hulls,
but eventually, after decades, they may be released,
contaminating the nearby area or drifting away with
the currents, probably for long distances, and then
returning to the surface. The impact of wrecks on the
abyssal seafloor has never been investigated, although
modern techniques are suitable for studying their
effects. This is demonstrated by the discovery of the
Titanic, corroding away at a depth of 3800 m in the
Northwest Atlantic since 1912, and by the detection of
the Lucona at a depth of 4511 m in the Indian Ocean,
as part of the investigation of an insurance fraud since
1977 (Mullen, 1991).
Waste disposal in the deep ocean
The production of wastes in human societies is tremen-