Environmental Issues of Deep-Sea Mining

Sharma, Rahul

doi:10.1016/j.proeps.2015.06.026

Cited by 85 publications

(46 citation statements)

References 5 publications

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“…In addition, no overburden will need to be removed before mining can take place, as the deposits of interest are exposed at the ocean floor. Other crucial drivers of deepsea mining include the fact that many of the deposits that are present at a single marine mine site contain three or more metals of economic interest 8,10,11 . Small deposits can be selectively mined simply by moving the productionmining vessel from one high-grade deposit to another, without the need to process intervening low-grade material.…”

Section: Unique (Or Favourable) Characteristics Of Deep-ocean Miningmentioning

confidence: 99%

Deep-ocean polymetallic nodules as a resource for critical materials

Hein

Koschinsky

Kühn

2020

Nat Rev Earth Environ

255

127

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Deep-ocean polymetallic nodules (also known as manganese nodules) are composed of iron and manganese oxides that accrete around a nucleus on the vast abyssal plains of the global ocean 1-6. Polymetallic nodules vary in diameter from less than one to tens of centi metres and acquire economically interesting quantities of critical metals (metals that are essential to the security and economic wellbeing of a nation) from ocean water and/or sediment pore waters. As a result, the enormous quantities of these nodules-which are conservatively estimated to total 21 billion dry tons in the Clarion-Clipperton Zone 7,8 (CCZ; located in the northeast equatorial Pacific Ocean) alone (Fig. 1)-host considerable tonnages of critical metals that are essential for green energy, vehicles and infrastructure, as well as for new technology and military applications. This reservoir of critical metals has, therefore, triggered interest in new deep-ocean mining operations. However, the potential environmental impacts of such activities are of great concern and have hastened extensive research and evaluation in this area 9-11. Polymetallic nodules were first discovered on the seabed at a depth of approximately 4,300-5,500 m during the 1872-1876 voyage of the HMS Challenger to study the deep ocean 12. A number of nodules, which contained numerous shark teeth and cetacean ear bones, were collected from the western end of the CCZ nodule field 12. Early hypotheses suggested that polymetallic nodules form by alteration of volcanic rocks and grains, especially glass, which are transformed into manganese carbonates and, finally, into oxides that are deposited from solution to form nodules on water-rich sediments 12-14. However, later work-aided in part by the 1957-1958 International Geophysical Year-revealed the general source of the metals (seawater and sediment pore water) and the sorption processes that might be involved in the acquisition of minor metals by nodules 15-20. Economic interest in the deep-ocean polymetallic nodules developed in the 1960s 15,16 , which subsequently led to the formation of consortia in Germany,

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Section: Unique (Or Favourable) Characteristics Of Deep-ocean Miningmentioning

confidence: 99%

Deep-ocean polymetallic nodules as a resource for critical materials

Hein

Koschinsky

Kühn

2020

Nat Rev Earth Environ

255

127

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“…[9] As such, it is desirable to limit any negative environmental impacts so far as practicable, for example, by minimising the interaction between the collector system and seafloor; ensuring separation of minerals from sediments close to the seabed; and strip-wise mining (leaving alternate strips of undisturbed seafloor). [10] In all of these areas, in situ elemental analysis of the materials involved will be critical to achieving best results. The minerals of interest for ocean mining are present in three forms:…”

Section: Introductionmentioning

confidence: 99%

Prototype GaAs X‐ray detector and preamplifier electronics for a deep seabed mineral XRF spectrometer

Lioliou

Barnett

2017

X-Ray Spectrometry

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Work towards developing a prototype GaAs based X-ray fluorescence spectrometer focusing on the detector-preamplifier system for in situ characterisation of deep seabed minerals is presented. Such an instrument could be useful for marine geology and provide insight into hydrothermal processes. It would also be beneficial for deep sea mining applications. The GaAs photodiode was electrically characterised at 4°C (ambient seawater temperature) and 33°C. A system energy resolution (full width at half maximum) at 5.9 keV of 580 eV at 4°C, limited by the dielectric noise, broadening to 680 eV at 33°C, was recorded. The spectral performance of the system was characterised across the energy range 4.95 keV to 21.17 keV, at 33°C, using high-purity X-ray fluorescence calibration samples excited by a Mo target X-ray tube. The charge output from the system was found to be linear with incident photon energy. The energy resolution was found to broaden from 695 eV at 4.95 keV to 735 eV at 21.17 keV, attributed to the increasing Fano noise with energy. The same X-ray tube was used to fluoresce an unprepared manganese nodule (revealing the presence of Mn, Fe, Ni, Cu, Zn, Pb, Sr, and Mo) and a black smoker hydrothermal vent sample (containing Fe, Co, Ni, Cu, Zn, Pb, and Mo). Such a spectrometer may also find use in future space missions to study the hydrothermal vents that are believed to exist in the oceans of Jupiter's moon Europa. | INTRODUCTIONIn recent years, there has been renewed interest in deep ocean exploration for economic as well as scientific reasons. Economic interest in the seabed is motivated by the availability of valuable minerals in the deep ocean.[1] At present, elemental characterisation of seabed mineral deposits requires samples to be retrieved and transported to either a surface vessel or to shore.[2]The development of instrumentation for in situ elemental analysis (e.g., X-ray fluorescence spectrometry, XRF) in the ocean would revolutionise scientifically motivated and economically motivated surveying and prospecting. A remotely operated vehicle equipped with an XRF spectrometer or neutron activation analysis package has been proposed for this application.[3] For mining, in situ elemental analysis technology may also be used throughout the mine site's life to continually monitor the collection of materials and to ensure that any tailings returned to the seabed are of appropriate composition to minimise impact on the surrounding ecosystem. -----------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Several reviews (e.g., Smith, 1999;Sharma, 2015;Jones et al, 2017) concluded that there is a lack of information on the potential impact of sediment burial at the scale of the CCZ and that there would be considerable long-term negative effects on the ecosystem.…”

Section: Sedimentation Rates and Mixing Sediment Plumesmentioning

confidence: 99%

“…These arise because, according to Sharma (2015), for every ton of manganese nodule mined, 2.5-0.5 tons of sediment will be resuspended. Adjacent areas will obviously experience the highest sedimentation rates, but sediment plumes will remain in suspension over long periods and also travel laterally.…”

Section: Sedimentation Rates and Mixing Sediment Plumesmentioning

confidence: 99%

The Benthic Megafaunal Assemblages of the CCZ (Eastern Pacific) and an Approach to their Management in the Face of Threatened Anthropogenic Impacts

et al. 2018

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We present here the results of a UNESCO/IOC baseline study of the megafaunal assemblages of the polymetallic nodule ecosystem of 5 areas within the Clarion Clipperton Zone (CCZ) of the eastern Pacific Ocean. The work was undertaken with a view to investigating the structure of the epifaunal populations associated with the benthic biotopes being targeted for nodule mining and developing an appropriate set of management tools and options. The general characteristics of nodule ecosystem and assemblages and their sensitivity to deep-sea mining are discussed in relation to water masses, surface to seabed water circulation, the nepheloid layer and processes taking place at the sediment interface. Management tools considered include species diversity and vulnerability indexes, GIS systems, zoning, and 3D rapid environmental assessment (REA). These strategies are proposed for trial during pilot mining operations within the CCZ.

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Environmental Issues of Deep-Sea Mining

Cited by 85 publications

References 5 publications

Deep-ocean polymetallic nodules as a resource for critical materials

Deep-ocean polymetallic nodules as a resource for critical materials

Prototype GaAs X‐ray detector and preamplifier electronics for a deep seabed mineral XRF spectrometer

The Benthic Megafaunal Assemblages of the CCZ (Eastern Pacific) and an Approach to their Management in the Face of Threatened Anthropogenic Impacts

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