440
Hjalmar THIEL
and obstacles for currents should be viewed as if they
were “experimental” environmental changes, and their
influence on the physico-biological system should be
studied together with the distribution of anthropogenic
radionuclides.
Essential for such investigations are close-up observations and narrowly spaced sampling in the vicinity of
the sources, and this demands the use of manned submersibles and/or remotely operated vehicles (ROVs). It
is important to obtain visual impressions of organism
growth on the sunken submersibles and on the drums,
and to observe corrosion and its influence on the
sediments and animals.
Drums with radioactive wastes, lost nuclear submarines, munition dumping and shipwrecks in the deep
sea together offer an arsenal of “experimental” facilities
which should be used to answer basic questions on the
ecology of the deep sea and to respond to questions on
applied problems and societal needs.
All dumping activities included low-level wastes.
The disposal of high-level wastes was discussed by various committees but abandoned. However, the option
of burial below the seafloor may be reconsidered one
day, and would need further research for environmental
evaluation (Hollister and Nadis, 1998).
Sewage sludge and dredge spoil
As an example of deep-ocean dumping of sewage
sludge, one may cite a case from the Northwest
Atlantic. The Deepwater (Municipal) Dump site 106
(DWD 106) was established in 1986, some 106 nautical
miles off the coasts of New York and New Jersey,
at about 39º49
N, 72º08
W and 2500 m depth. This
site received approximately 36 million tonnes of wet
sewage sludge between March 1986 and July 1992 (Fry
and Butman, 1991).
An interdisciplinary team of investigators studied the
impact of DWD 106 while it was in use. Numerical
models had predicted the area over which sludge would
settle; and it was found that the material reached
the seafloor in significant amounts somewhat west
of the dump site. Clear faunal changes and higher
concentrations of contaminants were discovered. The
indicators used for the detection of sewage sludge were
silver, originating from the photographic and electronic
industries, linear alkylbenzenes, derived from wetting
agents in detergents, the sterol coprostanol and spores
from Clostridium perfringens originating from faecal
material of mammals [see Bothner et al. (1994) and
references therein].
As part of these studies, Van Dover et al. (1992)
reported different ratios of stable-isotopes in the tissue
of sea urchins and other large species after feeding on
sludge material, and Grassle (1991) found numerical
increases in several species of macrofauna in the zone
impacted by sewage sludge, compared to more distant
reference areas.
These impact studies aroused environmental concerns, and led to a reduction in dumping rate at
DWD 106 from 1991; by late summer of 1992 measurable improvements of the environmental conditions
had resulted. However, 50 nautical miles downstream
pollutant indicators had increased.
Sewage sludge changes the seafloor community
and may destroy it totally in areas of settlement.
Examples from shallow waters have been given by
Pearson et al. (1986) and Rees et al. (1992). This
waste material derived from water purification plants
and its composition depends on input materials and
treatment. Basically it contains domestic discharges;
but many drainage systems also receive rain water and
the run-off from roads, enriched with hydrocarbons.
Industrial waste water may add toxic substances like
heavy metals, and anthropogenic contaminants like persistent organochloric materials (e.g., PCBs). Whereas
coarser materials, organic matter and nutrient salts
may be separated from the sludge in the purification
plants, the content of organic matter remains high at
about 5%, and contaminants cannot be separated before
permanent storage. The thirteen European countries
which are Contracting Parties to the Oslo Convention
will produce nearly 10 million tonnes of dry sludge per
year when the secondary-treatment step (to diminish
the organic matter) is introduced in all plants. Many
of them have already added the third step (to reduce
plant nutrients).
The main components of a typical sludge are:
• inert materials predominantly consisting of extremely fine particles of silica, most of which are
<100 mm in diameter; they tend to flocculate in seawater;
• reactive organic materials, which are predominantly
cellulose fibres, higher fatty acids and oils;
• organic nitrogen compounds ranging from 6–
10% and creating a chemical oxygen demand of
2000 ml O 2 g
−1 ;
• persistent organic materials, such as polychlorinated biphenyls (PCBs);
• inorganic solutes, for example the liquid component
contains about 1000 ppm of ammonia;
Hjalmar THIEL
and obstacles for currents should be viewed as if they
were “experimental” environmental changes, and their
influence on the physico-biological system should be
studied together with the distribution of anthropogenic
radionuclides.
Essential for such investigations are close-up observations and narrowly spaced sampling in the vicinity of
the sources, and this demands the use of manned submersibles and/or remotely operated vehicles (ROVs). It
is important to obtain visual impressions of organism
growth on the sunken submersibles and on the drums,
and to observe corrosion and its influence on the
sediments and animals.
Drums with radioactive wastes, lost nuclear submarines, munition dumping and shipwrecks in the deep
sea together offer an arsenal of “experimental” facilities
which should be used to answer basic questions on the
ecology of the deep sea and to respond to questions on
applied problems and societal needs.
All dumping activities included low-level wastes.
The disposal of high-level wastes was discussed by various committees but abandoned. However, the option
of burial below the seafloor may be reconsidered one
day, and would need further research for environmental
evaluation (Hollister and Nadis, 1998).
Sewage sludge and dredge spoil
As an example of deep-ocean dumping of sewage
sludge, one may cite a case from the Northwest
Atlantic. The Deepwater (Municipal) Dump site 106
(DWD 106) was established in 1986, some 106 nautical
miles off the coasts of New York and New Jersey,
at about 39º49
N, 72º08
W and 2500 m depth. This
site received approximately 36 million tonnes of wet
sewage sludge between March 1986 and July 1992 (Fry
and Butman, 1991).
An interdisciplinary team of investigators studied the
impact of DWD 106 while it was in use. Numerical
models had predicted the area over which sludge would
settle; and it was found that the material reached
the seafloor in significant amounts somewhat west
of the dump site. Clear faunal changes and higher
concentrations of contaminants were discovered. The
indicators used for the detection of sewage sludge were
silver, originating from the photographic and electronic
industries, linear alkylbenzenes, derived from wetting
agents in detergents, the sterol coprostanol and spores
from Clostridium perfringens originating from faecal
material of mammals [see Bothner et al. (1994) and
references therein].
As part of these studies, Van Dover et al. (1992)
reported different ratios of stable-isotopes in the tissue
of sea urchins and other large species after feeding on
sludge material, and Grassle (1991) found numerical
increases in several species of macrofauna in the zone
impacted by sewage sludge, compared to more distant
reference areas.
These impact studies aroused environmental concerns, and led to a reduction in dumping rate at
DWD 106 from 1991; by late summer of 1992 measurable improvements of the environmental conditions
had resulted. However, 50 nautical miles downstream
pollutant indicators had increased.
Sewage sludge changes the seafloor community
and may destroy it totally in areas of settlement.
Examples from shallow waters have been given by
Pearson et al. (1986) and Rees et al. (1992). This
waste material derived from water purification plants
and its composition depends on input materials and
treatment. Basically it contains domestic discharges;
but many drainage systems also receive rain water and
the run-off from roads, enriched with hydrocarbons.
Industrial waste water may add toxic substances like
heavy metals, and anthropogenic contaminants like persistent organochloric materials (e.g., PCBs). Whereas
coarser materials, organic matter and nutrient salts
may be separated from the sludge in the purification
plants, the content of organic matter remains high at
about 5%, and contaminants cannot be separated before
permanent storage. The thirteen European countries
which are Contracting Parties to the Oslo Convention
will produce nearly 10 million tonnes of dry sludge per
year when the secondary-treatment step (to diminish
the organic matter) is introduced in all plants. Many
of them have already added the third step (to reduce
plant nutrients).
The main components of a typical sludge are:
• inert materials predominantly consisting of extremely fine particles of silica, most of which are
<100 mm in diameter; they tend to flocculate in seawater;
• reactive organic materials, which are predominantly
cellulose fibres, higher fatty acids and oils;
• organic nitrogen compounds ranging from 6–
10% and creating a chemical oxygen demand of
2000 ml O 2 g
−1 ;
• persistent organic materials, such as polychlorinated biphenyls (PCBs);
• inorganic solutes, for example the liquid component
contains about 1000 ppm of ammonia;