Deep sea mining is nothing but extraction of minerals from the floor of the ocean, and it is considered as a relatively new term for extraction of the minerals. Deep sea generally contains abundant mineral resources like polymetallic nodules, manganese crust, cobalt, silver, gold, copper and hydrothermal deposits.
In this century ocean mining activities will be used for utilization of mineral wealth for the goodwill and benefit of mankind. Ocean mining sites are generally found in large areas of polymetallic nodules at about 1400-3700 meters below the ocean surface as polymetallic nodules contains copper, cobalt nickel, and manganese polymettalic nodules which are viewed as potential resources to meet the demand for these metals worldwide.
As deep sea mining operations are carried out very heavily worldwide it has raised some questions about environmental damages in the surrounding areas of the mines.
Laws and regulations for deep sea mining : From the period 1973 to 1982, the first regulation regarding deep sea mining evolved, but the regulation came into force in 1994. This law came into existence through the United Nations convention and was a description on Law of Sea. International seabed authority (ISA) is a regulatory authority that regulates nations, which are having ventures in deep sea mining their own country. The ISA also requires nations, which are interested in deep sea mining to explore two mining sites out of which one should be handed over to ISA, along with transfer of technology for the period of 10 to 20 years. As this seems very profitable business some of the industrialized countries refused to sign on this treaty initially in 1982. Resources mined- Deep sea mine contains various resources for extraction such as silver, gold, cobalt, manganese, copper and zinc. Seabed is yet another area, which provides a valuable asset that is diamonds.
Extraction methods : For extraction of minerals, the recent technologies are very much important, which generally includes the use of remotely operated vehicles (ROVs) which are used for the collection of samples of minerals from the various prospective mining sites. Samples are obtained by ROVs with the help of drill and other cutting equipments for the analysis of precious minerals. After locating the site, a station or a mining ship is bought up to the mining area. There are two methods, which are generally used for extraction of the minerals for full time operations. These are as follows:
- Continuous line bucket system (CLB) - CLB is the ideal method for nodule collection. The method of operation for CLB is much like a conveyor-belt, which generally runs to the ocean’s surface from the floor of the sea where the chip extracts the minerals, and returns the tailing to the ocean.
Hydraulic suction system : In this method hydraulic suction mining a pipe is lowered towards the sea floor. The process begins with the transfer of nodules in the upward direction to the mining ship.
Environmental impacts : Deep Sea mining being a pretty new field, its ill-effects are yet to be known completely. But in terms of expert’s opinion removing parts of sea floor will ultimately result in disturbance to the lowest layer of land containing water, increase in toxicity of the water column and the tailings containing sediment plumes. Removal of the parts of the sea floor disturbs the habitat of underneath organisms. It may cause permanent instability to these organisms depending upon the type of mining and location. Apart from this the removal will also cause leakage, spills and corrosion. Among all this sediment plumes have the greatest impact because these plumes are caused when the tailing from mining generally fine particles are dumped back into the ocean, it ultimately creates clouds of particles and starts floating on the sea water. Generally, two types of plumes occur one is near the bottom, and another is on the surface. Bottom plumes occur when the tailings are pumped back to the mining site. The cloudiness or the turbidity of the water is increased by the floating particles. Surface plumes generally cause more serious problems. These plumes can spread over the vast areas depending on the size of the particles and water current. The plumes can make an impact on zooplankton and light penetration, in turn affecting the food web of the area.
