ANTHROPOGENIC IMPACTS ON THE DEEP SEA
455
vertical migration patterns, and the depth of the oxygen
minimum layer should determine the depth of mud
release. The resulting plume should be modelled and
evaluated. The same is necessary for the plume of
resuspended sediment above the seafloor created by the
mining vehicle during nodule uptake (see p. 451).
Impact experiments: This approach attempts to learn
about impacts by creating an experimental disturbance.
This should not be mistaken for simulation of fullscale disturbance by mining activities, since future
techniques and activity levels may not be known.
However, since such experiments cannot be undertaken in the laboratory, small-scale field experiments
should be designed to demonstrate certain aspects of
disturbances. Such small-scale impact experiments can
be envisaged as blanketing an area of several square
metres by using a submersible for exact deposition
of sediment in layers and its subsequent sampling.
Similarly, plume experiments could be conducted by
employing a submersible for disturbance at different
scales and for observations on sediment resettlement,
transport and plume sampling. Further large-scale
impact experiments may be conducted, after the results
of the benthic impact experiments and DISCOL are
made available (see also Thiel, ed., 2001).
Pre-pilot mining tests (PPMT): To be termed
“technique tests” in future documents of the International Seabed Authority. Industrial pre-pilot mining
tests can be expected to be conducted for testing
newly developed techniques. As in the DOMES and
MESEDA projects, disturbance would remain limited
and would rarely allow extrapolation to full-scale
activities. But accompanying those tests with an
environmental programme would help one to imagine
impacts and to ask the right questions in subsequent
work. Early discussions of experimental needs with
engineers may make it possible to design effective
environmental studies concurrently with technical tests.
Depending on the particular test, such experiments may
be concerned with the impact on the water column or
on the seafloor.
Pilot mining operations (PMO): To be termed
“mining tests” in future documents of the International
Seabed Authority. Industrial pilot mining operations
follow the pre-pilot mining tests, and can be defined
as pre-full-scale tests. Pilot mining operations are
duration tests for the techniques to be employed in
commercial exploitation. Technically a pilot mining
operation system may be somewhat scaled down, but
it will remain in operation for several months and the
disturbances caused at and above the seafloor and in
the water column will simulate the full-scale operation
correctly. Pilot mining operations provide the only
chance to extrapolate reliably to full-scale exploitation.
These opportunities should be exploited by oceanographers of all disciplines in an interdisciplinary and well
coordinated study.
International cooperation: The costs for a complete environmental pilot mining operation have been
roughly estimated already by Thiel et al. (1991) and by
Thiel and Foell (1993), who pointed out that no single
country, consortium or company would be able to
carry these costs, although they represent only a minor
part of the total technical development and exploration
phase. The only solution to the problem is international
partnership for the environment (Thiel and Schriever,
1993).
An environmental pilot mining operation represents
the final and most important step in environmental
impact assessment, but cooperative partnership should
be prepared and trained much earlier. It is essential
for the different disciplines to adopt the same methods,
to generate comparable results in baseline studies and
experimental approaches, to discuss the results, and
to know each other. Cooperation needs administrative
effort and communication, but the profit for all parties
will more than compensate for these efforts.
Below-seafloor resources and exploitation
The hydrocarbons, oil and gas, and in the future
probably methane hydrates, are important resources for
most human societies. Although in the narrow sense
they should not be regarded as marine resources, their
exploitation may nevertheless pollute the sea. Oil and
gas, for example, are located from a few hundred to
more than one thousand metres below the seafloor, but
their extraction from various geological facies requires
transport through the sea. This occurs in hermetically
enclosing systems, unless leakages or accidents allow
the oil to disturb the environment. Methane hydrates
may be located less deep in the sediment, even rather
close to the sediment surface; but most of this frozen
material is found deep under sediment layers.
Oil and gas
Regular impacts by drilling are introduced into
455
vertical migration patterns, and the depth of the oxygen
minimum layer should determine the depth of mud
release. The resulting plume should be modelled and
evaluated. The same is necessary for the plume of
resuspended sediment above the seafloor created by the
mining vehicle during nodule uptake (see p. 451).
Impact experiments: This approach attempts to learn
about impacts by creating an experimental disturbance.
This should not be mistaken for simulation of fullscale disturbance by mining activities, since future
techniques and activity levels may not be known.
However, since such experiments cannot be undertaken in the laboratory, small-scale field experiments
should be designed to demonstrate certain aspects of
disturbances. Such small-scale impact experiments can
be envisaged as blanketing an area of several square
metres by using a submersible for exact deposition
of sediment in layers and its subsequent sampling.
Similarly, plume experiments could be conducted by
employing a submersible for disturbance at different
scales and for observations on sediment resettlement,
transport and plume sampling. Further large-scale
impact experiments may be conducted, after the results
of the benthic impact experiments and DISCOL are
made available (see also Thiel, ed., 2001).
Pre-pilot mining tests (PPMT): To be termed
“technique tests” in future documents of the International Seabed Authority. Industrial pre-pilot mining
tests can be expected to be conducted for testing
newly developed techniques. As in the DOMES and
MESEDA projects, disturbance would remain limited
and would rarely allow extrapolation to full-scale
activities. But accompanying those tests with an
environmental programme would help one to imagine
impacts and to ask the right questions in subsequent
work. Early discussions of experimental needs with
engineers may make it possible to design effective
environmental studies concurrently with technical tests.
Depending on the particular test, such experiments may
be concerned with the impact on the water column or
on the seafloor.
Pilot mining operations (PMO): To be termed
“mining tests” in future documents of the International
Seabed Authority. Industrial pilot mining operations
follow the pre-pilot mining tests, and can be defined
as pre-full-scale tests. Pilot mining operations are
duration tests for the techniques to be employed in
commercial exploitation. Technically a pilot mining
operation system may be somewhat scaled down, but
it will remain in operation for several months and the
disturbances caused at and above the seafloor and in
the water column will simulate the full-scale operation
correctly. Pilot mining operations provide the only
chance to extrapolate reliably to full-scale exploitation.
These opportunities should be exploited by oceanographers of all disciplines in an interdisciplinary and well
coordinated study.
International cooperation: The costs for a complete environmental pilot mining operation have been
roughly estimated already by Thiel et al. (1991) and by
Thiel and Foell (1993), who pointed out that no single
country, consortium or company would be able to
carry these costs, although they represent only a minor
part of the total technical development and exploration
phase. The only solution to the problem is international
partnership for the environment (Thiel and Schriever,
1993).
An environmental pilot mining operation represents
the final and most important step in environmental
impact assessment, but cooperative partnership should
be prepared and trained much earlier. It is essential
for the different disciplines to adopt the same methods,
to generate comparable results in baseline studies and
experimental approaches, to discuss the results, and
to know each other. Cooperation needs administrative
effort and communication, but the profit for all parties
will more than compensate for these efforts.
Below-seafloor resources and exploitation
The hydrocarbons, oil and gas, and in the future
probably methane hydrates, are important resources for
most human societies. Although in the narrow sense
they should not be regarded as marine resources, their
exploitation may nevertheless pollute the sea. Oil and
gas, for example, are located from a few hundred to
more than one thousand metres below the seafloor, but
their extraction from various geological facies requires
transport through the sea. This occurs in hermetically
enclosing systems, unless leakages or accidents allow
the oil to disturb the environment. Methane hydrates
may be located less deep in the sediment, even rather
close to the sediment surface; but most of this frozen
material is found deep under sediment layers.
Oil and gas
Regular impacts by drilling are introduced into