standardization of environmental data and information - International ...

eplied that he did not think in situ measurements for specific gravity, bulk
density and shear strength were necessary from an ecological perspective.
Bearing strength was not too relevant to understanding the habitat, though
it was certainly relevant to engineering the mining equipment.
Grain size
Smith suggested that the Workshop consider how to measure grain
size. Bringing sediments up, disaggregating them and treating them with
hydrogen peroxide would not reveal their behaviour at the seafloor when
resuspended from a plume. The Workshop might recommend that thought
be given to a possible protocol to measure native sediment or in situ grain
size in a way that was relevant to plume prediction.
A participant expressed the view that grain size was an important
parameter, even for impact assessment, and thus it would be proper at this
stage to define how it should be measured rather than put it aside. Smith
responded that he did not know whether there was a standard method for
measuring in situ grain size. There were standards for bringing sediments
up, disaggregating them and then measuring mineralogical grain size, but
this was not done to assess environmental effects. The measurement was
useful, but there was much more about grain size that was relevant to
impact assessment.
A participant observed that, during the German DISCOL
(Disturbance Recolonisation) project, grain size had been analysed onboard
using multicorer samples. However, no protocols existed for that
exceptional study. He had done many comparative studies on grain-size
analysis but had found no method that gave unambiguous results. For
example, using a Coulter counter, he had obtained completely different
results when the samples were sieved in distilled water instead of seawater;
he was sure that the Coulter counter with seawater gave a more correct
answer.
Smith recounted his own experience with ecological studies of
sediment communities in the deep sea, in which sediments had been taken
just after recovery from box corers or multiple corers, immediately washed
in a cold room on nested sieves, fractionated and weighed in the laboratory,
giving a picture of what the sediments looked like in the field. Perhaps the
Workshop could devise a recommendation on how to handle sediments.
Shear strength
INTERNATIONALSEABED AUTHORITY 297