standardization of environmental data and information - International ...

The paper went on to make recommendations for future benthic
disturbance experiments that would overcome some of these shortcomings.
The recommendations call for greater sediment discharge, discharge at a
higher point above the bottom to assess the effects of dispersion of the mining
plume, a towing pattern that would move the disturber (simulated mining
vehicle) over a greater seabed area during a longer time period, an
autonomous disturber in the form of a remotely operated vehicle rather than
one tethered to the control vessel, and real-time assessment of impact through
live television and other devices.
Also included in the paper are design suggestions to limit the
environmental impact from mining. These are: minimizing sediment
penetration by the collector and mining vehicle, avoiding the disturbance of the
more solid layer below the surface, reducing the mass of sediment swirled up
into the water near the bottom, laying more of the churned-up sediment
immediately behind the mining vehicle, minimizing the transport of sediment to
the ocean surface, reducing the discharge of tailings (mining wastes) into lower
waters, and reducing the drift of tailings by increasing their sedimentation rate.
In his oral presentation, Dr. Sharma said that, when collecting
environmental data, the needs of mining engineers and planners should be
borne in mind, since the data could also be useful for designing systems for
mining and environmental conservation. On the seafloor, for example,
engineers could use such data for mine-site selection, coping with
topographical obstructions and the design of mining-system components.
He described how the five previous benthic impact experiments had
differed in ways that made comparison of the results difficult, including
observation periods of different lengths, inconsistent sampling of sedimentcore
slices, and the use of different techniques to measure water content and
density of sediments.
The discussion highlighted the difficulty in trying to assess mining
impacts from the limited tests performed so far. One participant also
expressed surprise at the number of parameters that Sharma had listed for
measurement, stating that if the costs of environmental studies were too high,
investors would turn to less costly operations elsewhere. Smith observed that
a balance had to be struck between what people would like to know and what
they needed to know about the ocean and the impacts.
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INTERNATIONAL SEABED AUTHORITY