standardization of environmental data and information - International ...

morphology (basin, slope, ridge, plateau), sediment character (thickness,
stratification, erosion) and fine-scale surface features (nodule coverage,
geological fault steps); (3) sample gathering and preservation, and (4)
laboratory tests and modelling.
In his oral presentation, Dr. Wiedicke described the great variety of
topographic forms and sediment-distribution patterns that had been
discovered in this area, and pointed out that such differences were likely to
show up in the benthic communities as well. For example, a species
collected from a slope might not occur elsewhere. In some places, the
Quaternary Period sediments in which manganese nodules were found had
been eroded away, leaving Tertiary sediments barren of nodules that had a
completely different chemical composition and animal community. Isotope
measurements at different sediment depths showed glacial depositions
much deeper than would be expected, indicating vertical movement of
sediment by bioturbation (caused by the activity of burrowing animals).
Reviewing calculations of mining impacts derived from laboratory
tests and modelling, he said one group had calculated that the bottom
plume produced by the mining vehicle would have only local effects.
However, he said the calculations demonstrated the great need for
additional parameters before the numbers could be taken seriously.
Regarding the effects of tailings (mineral wastes) discarded by processing
vessels, he said the calculations favoured release of this material as close
to the bottom as possible to avoid extensive spreading, even onto nearby
coastlines. Again, he observed that precise information on grain size was
needed before reliable modelling was possible.
Dr. Huiayang Zhou, a professor of geochemistry at the Second
Institute of Oceanography, Hangzhou, China, spoke of work done by the
China Ocean Mineral Resources Research and Development Association
(COMRA). He described two aspects of this work: environmental
assessment in the Chinese exploration area of the Clarion-Clipperton
Fracture Zone (CCFZ) and a mining simulation study conducted in a Chinese
lake.
The monitoring programme in the Pacific, operating since 1995,
was called NaVaBa, for Natural Variability of Baseline. About 50 scientists
had been involved in hydrographic, biological, chemical and
sedimentological assessment. Among the discoveries had been an area of
mineral assemblages with temperatures above 70 degrees, possibly
indicating hydrothermal activity. Interannual variability in temperature and
90
INTERNATIONAL SEABED AUTHORITY