Heavy Metals on the Deep-Sea Floor
289
Fig. 10.9. Beach placers. The beach south of Quilon (SW India) has a heavy mineral deposit on the
top part (where the boat rests). During SW monsoon, high waves sort the sand as shown in Fig.
10.8., and produce layers of "black sand" (inset). The inset profile is 20 cm high. [Photo E. S.]
10.4 Heavy Metals on the Deep-Sea Floor
10.4.1 Importance of Manganese Deposits. The rich metal deposits on the deep-sea
floor have been a favorite topic of discussion among marine geologists ever since the
manganese nodules (better: ferromanganese concretions) were discovered by the
Challenger Expedition a century ago and were shown to be rich in copper, cobalt,
nickel, and other heavy metals (Fig. 10.10). The abundances of these metals in
seawater are extremely low, largely due to the low solubility of their oxides and
hydroxides. Also, they are readily extracted by biological processes, and sent to the
sea floor within organic matter.
The amount of nodules on the Pacific Ocean floor seems to be in the neighborhood of 100 to 200 billion tons . What is the economic value of these deposits? Right
now, close to zero. It is too expensive and (because of complex international legal
problems) too risky to mine them, transport the material back to shore, extract the
wanted heavy metals, market them, and still make a profit. Nevertheless, there is a
potential value, if prices of copper, nickel, and cobalt rise high enough. This potential
value is a bone of contention among UN members: those nations technically unable
to mine the material wish to make sure that those able to do so must share the profits,
if any should materialize. In addition, metal-exporting countries are apprehensive
289
Fig. 10.9. Beach placers. The beach south of Quilon (SW India) has a heavy mineral deposit on the
top part (where the boat rests). During SW monsoon, high waves sort the sand as shown in Fig.
10.8., and produce layers of "black sand" (inset). The inset profile is 20 cm high. [Photo E. S.]
10.4 Heavy Metals on the Deep-Sea Floor
10.4.1 Importance of Manganese Deposits. The rich metal deposits on the deep-sea
floor have been a favorite topic of discussion among marine geologists ever since the
manganese nodules (better: ferromanganese concretions) were discovered by the
Challenger Expedition a century ago and were shown to be rich in copper, cobalt,
nickel, and other heavy metals (Fig. 10.10). The abundances of these metals in
seawater are extremely low, largely due to the low solubility of their oxides and
hydroxides. Also, they are readily extracted by biological processes, and sent to the
sea floor within organic matter.
The amount of nodules on the Pacific Ocean floor seems to be in the neighborhood of 100 to 200 billion tons . What is the economic value of these deposits? Right
now, close to zero. It is too expensive and (because of complex international legal
problems) too risky to mine them, transport the material back to shore, extract the
wanted heavy metals, market them, and still make a profit. Nevertheless, there is a
potential value, if prices of copper, nickel, and cobalt rise high enough. This potential
value is a bone of contention among UN members: those nations technically unable
to mine the material wish to make sure that those able to do so must share the profits,
if any should materialize. In addition, metal-exporting countries are apprehensive