Deep-Sea Mining Methods and Concerns

Deep-sea mining has increased over the past decade due to demand for precious metals and phosphorus nodule mining, which is the best source for artificial fertilizer. The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed. Polymetallic nodules, which contain nickel, copper, cobalt and manganese, are found at depth of 4000 – 6000 meter. Manganese crusts are available at 800-2400 meter. Mainly cobalt, some vanadium, molybdenum and platinum are found in it. Sulfide deposits are found at an average depth of 1400-3700, which contains copper, lead, zinc, some gold and silver. Diamonds are also mined from the seabed. Remotely Operated Vehicles are used equipped with drills to gather samples that are then analyzed for precious metals. A mining ship or station is set up once a location is located.  Two systems are used in mining minerals. HS or hydraulic suction and CLB or continuous line bucket system. The hydraulic suction system uses two separate pipes, one for collecting nodules and the other for returning trailing. CLB works in a similar fashion to a conveyor belt by running from the sea floor to the surface where the ship or platform extracts the desired material. There are a number of environmental concerns including disturbing the ecosystems that are unique to these sites, as well as causing toxicity of the water column and food web. Removal of parts of the sea floor will disturb the benthic layer. The type of mining and location will cause permanent disturbance to the habitat of benthic organisms. Besides this direct impact of mining the area, leakages, spills and corrosion would alter the chemical make-up of this area.