The mining process does not present a major technological challenge because the nodules can be removed fairly
easily from the surface of the sediment-covered seabed
on which they rest. Trial excavation as early as 1978 was
successful in transporting Mn nodules to a ship. New technology for the mining equipment is under development
and is being scaled-up to work in larger areas for longterm operations. Riser pipe or other lifting technologies
required to transport the ore from the seabed to the ship
developed in the 1970s are also being improved with modern technology. The actual area of seabed that is mined
will probably not exceed about 25 % of the 75,000 square
km contract sites because of topographic obstacles and the
lower abundance distribution of nodules. Before largescale mining of nodules can be carried out, questions
related to the environmental impact of mining activities
must be addressed. Mining of Mn nodules would considerably disturb parts of the seabed and suspend sediment
that will be carried by currents for as yet to be determined
distances. The development of mining technology that
significantly reduces the sediment plume would be an
important advancement.
Summary
Mn nodules are found on the surface of sediment on all
abyssal plains throughout the global ocean where sedimentation rates are low, less than 10 cm per thousand
years. Nodules generally grow at rates of a few tens of
mm per million years, yet they remain at the sediment surface even though sedimentation rates are four orders of
magnitude higher, which is still a mystery. Nodules are
composed predominantly of Mn minerals that precipitate
from seawater and from sediment pore fluids and acquire
abundant metals and other elements from those two
sources by adsorption. Metals essential to many emerging
technologies are enriched in nodules (Ni, Cu, Co, Mo, Li,
Zr, REEs) to the extent that they are considered a potential
resource for mining in the near future. Fifteen contracts for
exploration for nodules have been taken out or are pending
with the ISA that cover more than one million square km
of seabed.
Bibliography
Baturin, G. N., 1988. The Geochemistry of Manganese and Manganese Nodules in the Ocean. Dordrecht: D. Reidel.
Cronan, D. S., 2006. Processes in the formation of central Pacific
manganese nodule deposits. Journal of Marine Science and the
Environment, C4, 41–48.
Halbach, P., Friedrich, G., and von Stackelberg, U. (eds.), 1988. The
Manganese Nodule Belt of the Pacific Ocean – Geological Environment Nodule Formation, and Mining Aspects. Stuttgart:
Ferdinand Enke Verlag. 254 pp.
Hein, J. R., and Koschinsky, A., 2014. Deep-ocean ferromanganese
crusts and nodules. In Holland, H. D., and Turekian, K. K. (eds.),
Treatise on Geochemistry, Chapter 11. Oxford: Elsevier, Vol.
13, pp. 273–291.
Hein, J. R., Mizell, K., Koschinsky, A., and Conrad, T. A., 2013.
Deep-ocean mineral deposits as a source of critical metals for
high- and green-technology applications: comparison with
land-based deposits. Ore Geology Reviews, 51, 1–14.
ISA, 1999. Deep-Seabed Polymetallic Nodule Exploration: Development of Environmental Guidelines, ISA/99/02. Kingston:
International Seabed Authority. 289.
ISA, 2010. A Geological Model of Polymetallic Nodule Deposits in
the Clarion-Clipperton Fracture Zone. Kingston: International
Seabed Authority. ISA Technical Study, Vol. 6, p. 105.
Mero, J. L., 1962. Ocean-floor manganese nodules. Economic
Geology, 57, 747–767.
Mero, J. L., 1965. The Mineral Resources of the Sea. Amsterdam:
Elsevier.
Verlaan, P. A., Cronan, D. S., and Morgan, C. L., 2004.
A comparative analysis of compositional variations in and
between marine ferromanganese nodules and crusts in the South
Pacific and their environmental controls. Progress in Oceanography, 63, 125–158.
Cross-references
Abyssal Plains
Carbonate Dissolution
Calcite Compensation Depth (CCD)
Deep-sea Sediments
Dust in the Ocean
Energy Resources
Geochronology: Uranium-Series Dating of Ocean Formations
Cobalt-rich Manganese Crusts
Marine Mineral Resources
Paleoceanographic Proxies
Paleoceanography
Radiogenic Tracers
Seamounts
Technology in Marine Geosciences
MANGROVE COASTS
Norman C. Duke
James Cook University, TropWATER – Centre for
Tropical Water and Aquatic Ecosystem Research,
Townsville, QLD, Australia
Synonyms
Coastal swampland; Coastal swamps; Coastal wetland;
Mangrove forested coast; Mangrove shoreline; Tidal wetland coast
Definition
Mangrove Forests: Vegetated tidal habitat comprised of
saltwater-tolerant trees and shrubs. Mangroves are part of
a unique combination of plant types called tidal forests or
mangrove forests to distinguish them from individual trees
and shrubs, also called mangroves.
Mangrove Plants: Mangroves are trees, shrubs, palms,
or ground ferns, generally exceeding one-half meter in
height, that normally grow above mean sea-level and
below highest tidal levels in soft sediments along the intertidal zone of less exposed marine coastal environments
and estuarine margins.
412
MANGROVE COASTS
easily from the surface of the sediment-covered seabed
on which they rest. Trial excavation as early as 1978 was
successful in transporting Mn nodules to a ship. New technology for the mining equipment is under development
and is being scaled-up to work in larger areas for longterm operations. Riser pipe or other lifting technologies
required to transport the ore from the seabed to the ship
developed in the 1970s are also being improved with modern technology. The actual area of seabed that is mined
will probably not exceed about 25 % of the 75,000 square
km contract sites because of topographic obstacles and the
lower abundance distribution of nodules. Before largescale mining of nodules can be carried out, questions
related to the environmental impact of mining activities
must be addressed. Mining of Mn nodules would considerably disturb parts of the seabed and suspend sediment
that will be carried by currents for as yet to be determined
distances. The development of mining technology that
significantly reduces the sediment plume would be an
important advancement.
Summary
Mn nodules are found on the surface of sediment on all
abyssal plains throughout the global ocean where sedimentation rates are low, less than 10 cm per thousand
years. Nodules generally grow at rates of a few tens of
mm per million years, yet they remain at the sediment surface even though sedimentation rates are four orders of
magnitude higher, which is still a mystery. Nodules are
composed predominantly of Mn minerals that precipitate
from seawater and from sediment pore fluids and acquire
abundant metals and other elements from those two
sources by adsorption. Metals essential to many emerging
technologies are enriched in nodules (Ni, Cu, Co, Mo, Li,
Zr, REEs) to the extent that they are considered a potential
resource for mining in the near future. Fifteen contracts for
exploration for nodules have been taken out or are pending
with the ISA that cover more than one million square km
of seabed.
Bibliography
Baturin, G. N., 1988. The Geochemistry of Manganese and Manganese Nodules in the Ocean. Dordrecht: D. Reidel.
Cronan, D. S., 2006. Processes in the formation of central Pacific
manganese nodule deposits. Journal of Marine Science and the
Environment, C4, 41–48.
Halbach, P., Friedrich, G., and von Stackelberg, U. (eds.), 1988. The
Manganese Nodule Belt of the Pacific Ocean – Geological Environment Nodule Formation, and Mining Aspects. Stuttgart:
Ferdinand Enke Verlag. 254 pp.
Hein, J. R., and Koschinsky, A., 2014. Deep-ocean ferromanganese
crusts and nodules. In Holland, H. D., and Turekian, K. K. (eds.),
Treatise on Geochemistry, Chapter 11. Oxford: Elsevier, Vol.
13, pp. 273–291.
Hein, J. R., Mizell, K., Koschinsky, A., and Conrad, T. A., 2013.
Deep-ocean mineral deposits as a source of critical metals for
high- and green-technology applications: comparison with
land-based deposits. Ore Geology Reviews, 51, 1–14.
ISA, 1999. Deep-Seabed Polymetallic Nodule Exploration: Development of Environmental Guidelines, ISA/99/02. Kingston:
International Seabed Authority. 289.
ISA, 2010. A Geological Model of Polymetallic Nodule Deposits in
the Clarion-Clipperton Fracture Zone. Kingston: International
Seabed Authority. ISA Technical Study, Vol. 6, p. 105.
Mero, J. L., 1962. Ocean-floor manganese nodules. Economic
Geology, 57, 747–767.
Mero, J. L., 1965. The Mineral Resources of the Sea. Amsterdam:
Elsevier.
Verlaan, P. A., Cronan, D. S., and Morgan, C. L., 2004.
A comparative analysis of compositional variations in and
between marine ferromanganese nodules and crusts in the South
Pacific and their environmental controls. Progress in Oceanography, 63, 125–158.
Cross-references
Abyssal Plains
Carbonate Dissolution
Calcite Compensation Depth (CCD)
Deep-sea Sediments
Dust in the Ocean
Energy Resources
Geochronology: Uranium-Series Dating of Ocean Formations
Cobalt-rich Manganese Crusts
Marine Mineral Resources
Paleoceanographic Proxies
Paleoceanography
Radiogenic Tracers
Seamounts
Technology in Marine Geosciences
MANGROVE COASTS
Norman C. Duke
James Cook University, TropWATER – Centre for
Tropical Water and Aquatic Ecosystem Research,
Townsville, QLD, Australia
Synonyms
Coastal swampland; Coastal swamps; Coastal wetland;
Mangrove forested coast; Mangrove shoreline; Tidal wetland coast
Definition
Mangrove Forests: Vegetated tidal habitat comprised of
saltwater-tolerant trees and shrubs. Mangroves are part of
a unique combination of plant types called tidal forests or
mangrove forests to distinguish them from individual trees
and shrubs, also called mangroves.
Mangrove Plants: Mangroves are trees, shrubs, palms,
or ground ferns, generally exceeding one-half meter in
height, that normally grow above mean sea-level and
below highest tidal levels in soft sediments along the intertidal zone of less exposed marine coastal environments
and estuarine margins.
412
MANGROVE COASTS