28 
program to determine the environmental impact of deep sea mining.’ * 
In addition to damage of organisms in the mining path, bottom 
sediments stirred up by the mining operation may clog or smother 
benthic (bottom dwelling) organisms over a much wider area than 
that which is actually mined. This could make the reestablishment of 
the bottom ecosystem even more difficult. Depending on the magnitude 
of the sediment stirring problem, proposed unmined buffer zones for 
repopulation purposes may be ineffective unless made very wide. How- 
ever, it is not likely that entire species will be destroyed by mining 
operations as the present techniques are not 100 percent efficient im 
bottom coverage. 
TRANSPLANTATION 
Another possible consequence of the suspension of lifted sediments 
in the water column is the transplantation of spores or other dormant 
forms of microorganisms from one area, where they lay in the sedi- 
ment, to another, where they may be reactivated under favorable 
temperature, light, and oxygen conditions in the overlying water 
column. However, it has also been argued that the redistribution of 
sediments on the ocean floor from natural causes exceeds by several 
orders of magnitude any disturbance ever likely to be caused by deep 
sea mining.® 
SURFACE WATER CONTAMINATION 
The introduction of bottom water and material into the upper water 
layers is a complex problem and may prove either beneficial or deleteri- 
ous. Introduction of sediments and bottom material into the surface 
waters may increase trace-metal concentrations by leaching of nodules 
or sediments, which could inhibit photosynthesis or allow the accumu- 
lation of different trace metals within marine food chains. However, 
nodule material is not very likely to dissolve in the upper water layers. 
The oxide surfaces represent such effective adsorbents that trace metals 
are unlikely to be leached in large quantities, even though they are 
present at concentrations many times those in seawater. Some silicious 
material brought up as sediment could be expected to dissolve slightly 
increasing the silica (Si0.) content of the surface water. 
A likely effect on the surface water will be an increase in photo- 
synthetic activity and productivity resulting from the high nutrient 
concentration of the bottom water. The extent of this effect will be 
determined by the concentration of nutrients introduced into the sur- 
face water and the amount of time that this nutrient-rich water re- 
mains in the euphotic zone. A phytoplankton bloom should be bene- 
ficial if a food chain develops to consume it, otherwise decaying 
plankton may cause partial fouling of the water. However, because 
organic particulate material will oxidize slowly as it falls through 
the water column, the resultant decrease in oxygen concentration prob- 
ably will be very small and may not cause any significant fouling. 
Oxidation of organic material discharged in the mining effluent as a 
1 Ocean Science News. v. 16, No. 19, May 10, 1974, p. 2-3. 
2U.S. Department of Commerce. The environmental impact of deep-sea mining, progress 
report. NOAA Technical Report ERL 290—-OD 11, Boulder, Colo., 1973: 185 
U.S. Congress. Senate. Committee on Interior and Insular Affairs. Subcommitee on 
Minerals, Materials and Fuels. Hearings, 98d Congress, 2d session on Amendment No. 946 
to §8. 1134. Mar. 5, 6, and 11, 1974. Part 2, Washington, U.S. Govt. Print. Off., 1974. 
pp. 1091-1092. 
