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By Hunsoo Choi

Internal textures of manganese nodules from Clarion-Clipperton zone of northeastern Pacific Ocean are classified into five textural zones: columnar-textured layered zone, cuspate-textured layered zone, cuspate-textured massive zone, cuspate-textured porous zone and massive- textured massive zone. Vernadite is the main constituent mineral in the columnar- and cuspate-textured layered zone. Buserite sometimes occurs in the cuspate-textured layered zone. The cuspate-textured massive zone is mainly composed of buserite. Todorokite is also associated with buserite in the massive-textured porous zone, where cuspates and globes are partially replaced by massive texture. In the massive-textured massive zone, todorokite, buserite and birnessite occur together. The analyzed elements of all zones are also classified into four elemental groups by the cluster analysis of correlation coefficients: Mn group, Cu-Ni-Mg group, Fe group and Si group. Mn group consists of Mn and K. Cu-Ni-Mg group consists of Cu, Ni, Zn, Mg and/or Ca, Na. Fe group consists of Fe, Co, Ti and/or Ca, P. Si group consists of Si and Al. Each textural zone is composed of three or four elemental groups. These four elemental groups are correlated with mineral composition, such as, Mn group with todorokite, Cu-Ni-Mg group with buserite, Fe group with Co-bearing iron-oxyhydroxide minerals, and Si group with silicates.

Jan 1, 2002

By Michael Goldin, Jonathan Ladner, Thomas Peacock, Nathaniel Johnson, Patrick Haley, Kris van Nijen, Andrew Rzeznik, Pierre Lermusiaux, Matthew Alford, Carlos Munoz-Royo

Surface processing vessels for deep-sea nodule mining operations will produce dewatering plumes that will be released at some depth into the ocean water column. We are studying all aspects of this part of the nodule mining process. First, we have developed analytical and numerical models to determine the effects of highly non-uniform, realistic stratifications on forced, compressible plumes with finite initial size. The classical plume model is developed to take into account the effects of compressibility and thermal conduction through the dewatering pipe. Our results show how small-scale features of a realistic stratification can have a large effect on a plume, and provide a basis for determining at what depth dewatering plumes can be released. These results form the basis for our PLUMEX field experiments, in which we will study the dynamics of dewatering plumes over the course of one week of field tests from the vessel R/V Sally Ride. The field experiments will use a Remotely Operated Vehicle (ROV) and a Phased-Array Doppler Sonar (PADS) system to study the characteristics of the dewatering plumes. The subsequent transport of the material in the dewatering plume will be monitored via shipboard surveys and, potentially, Autonomous Underwater Vehicle (AUV) operations, and these studies will be integrated with near real-time, data assimilating numerical model predictions. The ultimate goal of this project is to develop a field validated, recommend strategy for the release and monitoring of dewatering plumes, to help inform the development of ISA regulations and the planning of industrial operations.

Jan 1, 2017

By I. Yu. Melekestseva, V. V. Zaykov

Paleooceanic structures of the Urals fold belt contain different volcanic-hosted massive sulfide deposits of the Urals, Kuroko and Cyprus types [Prokin, Buslaev, 1999]. Small Cobearing massive sulfide deposits, as Ishkinino, Ivanovka and Dergamysh, associated with ultramafites of the Main Urals fault, are less known. Interest to them had arisen after discoveries of the modern “black smokers” associated with ultramafic rocks of the Middle-Atlantic Ridge (MAR). Ores of the Urals deposits are enriched in Co (0.3 %) and Ni (0.6 %) that are concentrated in Co-Ni-Fe-sulfides, sulfarsenides, and arsenides. Ores also contain the increased gold contents – 3–6 ppm and up to 16 ppm in those saturated with As-bearing minerals. The aim of the paper is a comparison of precious metal mineralization in ores from the Paleozoic and modern ultramafic-hosted massive sulfides.

Aug 24, 2006

By Brian D. Bornhold

A comprehensive multi-disciplinary marine geological survey of northwestern Graham Island, Queen Charlotte Islands, British Columbia, Canada was conducted by Offshore Survey and Positioning Services Ltd. of Vancouver, B.C. on behalf of the Geological Survey of Canada; Energy, Mines & Resources Canada, Pacific Geoscience Centre, Sidney, B.C. Canada during October 1984 and July 1985. The aim of the survey was to map both the surficial geology and geomorphology in order to identify and evaluate the nature of the nearshore sedimentation and recent tectonics including stability (slumps and scarps) seafloor faults (frequency and displacements) and both the classification and consistency of soil type boundaries and properties. Data was acquired by utilizing conventional indirect applied marine geophysical techniques including side scan sonar, precision echo sounding and complimentary soil sampling. During October 1984 a total of 320 line kilometres of data including 180 soil samples were acquired. During July 1985 a total of 300 line kilometres of data were acquired including 150 soil samples.

Jan 1, 1985

By B. J. Bluck

Diamond mega-placers, in order to rank amongst the primary diamond deposits, are defined as => 70 m carats at =>95% gem quality. There is only one mega-placer known and that is found along the coast of southwestern Africa fringing the Kaapvaal craton. Placers are classified as residual when they are left on the craton, transient when being eroded into the exit drainage and terminal. Terminal placers, in being the final depositories of diamonds off the craton, have the greatest probability of being a mega-placer and such is the case in the placer deposits near the Orange River mouth, southwestern Africa. There are four main groups of conditions leading to the development of a mega-placer: the craton, the drainage, the nature of the environment at the terminus and the timing. The craton, in its role as the producer of diamonds is significant in respect to its size, diamond-fertility, the degree to which diamonds from successive kimberlite intrusions have been retained there and their availability to the final drainage yielding the mega-placer. Cratons in being buoyant have a tendency to leak diamonds into surrounding basins but in being incompressible often have orogens converge onto them resulting in lost sediment being returned as foreland basin fills. In order to concentrate a bulk of diamonds the drainage basin has to be large with a high proportion of it on the craton. The drainage yielding the mega-placer should ideally not have been preceded by older drainage and other systems that may have robbed the craton of earlier diamonds. The exits of diamonds from the craton need to be few in order to focus on their supply and the drainage network needs to be efficient in order to remove the maximum volume of diamonds off the craton. This efficiency and the focused termination is best achieved by the rejuvenation of a pre-existing drainage network. The drainage should be young enough to yield host sediments friable enough to allow brittle diamonds to be recovered from them.

Jan 1, 2004

By P. E. Mikhailk

From July 29 to September 15, 2004, the 178th cruise of the R/V Sonne took place under the KOMEX program in the Sea of Okhotsk. One of the cruise objectives was to dredge two different kinds of seamounts: 1 ? underwater volcanoes from the north slope of the Kurile Basin; 2 ? a seamount formed by tectonic (non volcanic) processes from the Kashevarov Trough. The underwater volcanoes are young edifices (0.84 ± 06 Ma, Baranov et al., 2002) with heights ranging from 150 to 300 m. Tops of the volcanoes are located at depth of 1260 to 2340 meters. The volcanic edifices are formed by olivine-clinopyroxene-plagioclase basalts. Dredge samples are covered by Fe-Mn crusts up to 40 mm thick. The seamount from the Kashevarov Trough is a tilted block. The height of the seamount is about 400 m and its top is located at a depth of 960 meters. Biotite hornfels, conglomerates, granodiorites, dropstones, and Fe-Mn crusts were recovered there. The thicknesses of crusts are up to 150 mm. Fe-Mn crusts from the underwater volcanoes differ from Fe-Mn crusts from the Kasevarov Trough seamount in morphology as well as in mineralogical and chemical compositions. The research was supported by the Program of the Presidium of the Far East Branch of the Russian Academy of Sciences (project ? 05-III-G-08-086).

Jan 1, 2005

By Brenda J. Burd

A very extensive spatial and temporal database on benthic infauna and associated sediment metals has been collected for Island Copper Mine on Vancouver Island, B.C. Canada from 1969 (pre-discharge) to 1998 (3 years post-discharge). The tailings deposited as organically impoverished, copper-rich, clays, silts and sands distributed according to particle size, bottom turbidity currents and strong, vertically mixed tidal currents. In addition, a large deposition of coarser waste rock along the north shore of Rupert Inlet contributed substantial material in the shallower, near-field area.

Jan 1, 2001

By Hjalmar Thiel

Since industry is progressing into the deep sea, marine scientists have expressed their concern about environmental disturbances which will be introduced by using the deep seafloor for mining metalliferous resources or as a repository for wastes. Environmental studies have been conducted on national levels and in bilateral or multilateral cooperation in the development of manganese nodule mining, as this is generally achieved in marine research. These investigations were partly large-scale and experimental approaches aiming at the assessment of the impacts expected to occur in commercial mining. The results elaborated till today and expected to be acquired in the foreseeable future may remain limited. Reliable impact evaluation will result from monitoring a Pilot Mining Operation (PMO). The lecture will present the broad outlines of a possible program and a preliminary calculation of approximate costs for such a combined industrial test and environmental monitoring event. Although the extent of necessary efforts for the environmental risks evaluation can only be estimated rather vaguely, it will become evident that the required human, technical, logistical, and financial resources to be mobilized will exceed industrial capacities and go beyond national funds. Therefore, such assessment of environmental risks is calling for broad international cooperation. While industrial developments for mining the deep sea will be ruled by competition or probably by restricted joint ventures, environmental care ranges outside competition and falls within the interest of all parties involved. Environmental studies, unlike technologies for the same function, do not primarily need duplication. International cooperation in PMO monitoring would equally well support all mining companies or consortia, it would minimize the efforts for all engaged in this challenging venture of deep-sea mining and it would maximize the precautionary discussion on and the care for the deep-sea environment.

Jan 1, 1994

By J. V. R. Prasada Rao

India is dependent for 60% of its annual requirement of copper and the entire quantity of nickel and cobalt on imports from outside the country. Land-based resources are either too meager or of too low a concentration for economic exploitation. This has prompted the country to look to deep seabed re- sources for meeting its rising demand for these metals. The Ocean Policy of the Government of India announced in 1982 talks about the need to map and assess the availability of minerals in the deep sea and to develop necessary technologies for exploration and exploitation of seabed minerals. To be self-reliant such technologies would have to be largely developed, tested and operated indigenously. The adoption of the Law of the Sea Convention in 1982 gave a fillip to India's desire to get into the field of deep seabed mining. India applied for recognition as a Pioneer Investor in Ocean Mining in 1983 and received allotment of a mine site of 150,000 km2 in the Central Indian Ocean in August 1987. Simultaneously, the Government has taken up a programme of development of technologies for exploration of the mine site for resource assessment, environmental monitoring also to meet the commitments like relinquishment of 50% of the area to the Preparatory Commission. Technologies for exploitation of these seabed resource like the mining system, transportation and extractive metallurgy have also been taken up for development in various research institutes largely in the government sector. While India's objective in the long term is to meet the shortage of copper, nickel, cobalt and manganese by the turn of the century, in the short term, the programme aims at application of the seabed mining technologies to meet the immediate needs of the country such as: a. Exploration for oil and natural gas. b. Exploration and exploitation of placer minerals and other deposits at shallow depth in India's EEZ.

Jan 1, 1994

By W. H. Pelton

Polymetallic sulphide (PMS) deposits have recently been discovered associated with hydrothermal vents on the sea floor off Vancouver Island, B.C. Visual estimates indicate reserves in excess of 1 million tons. Reliable reserve estimates have not yet been made, however, due to the extreme difficulty of drilling cores in 2 km of water. Few geophysical techniques can aid in the exploration of these deposits. There is little or no difference in radioactivity, magnetic susceptibility or electrical resistivity between the deposits and the surrounding sea floor sediments. This precludes radiometric, magnetic, electromagnetic and resistivity methods. There is a density contrast, but the logistics of gravity surveys at such depths are formidable. The physical property which shows the most contrast with the sea floor sediments, and which is perhaps one of the easiest to measure (with modern equipment) is polarizability. The induced polarization (IP) method is one of the major electrical geophysical techniques for exploring for PMS deposits on land.

Jan 1, 1985

By Thomas Pichler

In the past marine mining technology has focused on bulk mining of base metals from polymetallic massive sulfides. This has not been very successful because of the relatively low unit value of these metals and other reasons such as water depth, etc.. The process of gold enrichment in hydrothermal deposits is controlled through five different factors: (1) nature and source of the solution, (2) source of the gold, (3) a mechanism for mobilizing and transporting, (4) a mechanism for deposition, and (5) a mechanism to preserve the deposit. Gold has been identified in marine polymetallic massive sulfides from various locations on the ocean floor (e.g., spreading centers, seamounts) with contents ranging up to 5 ppm Au. This is within the current range of 1.0 to 7.0 ppm gold content which classifies gold ores. The gold appears to have been derived during hydrothermal alteration of the oceanic crust. Until the present there has been little attention to the possibility of mining gold or other precious metals in the marine environment. However, the magnitude of hydrothermal alteration (seawater can penetrates to a depth of 5 km into the oceanic crust) and primary gold contents of the rocks in the pathway of the fluid indicates that major gold deposits must have formed on or in the ocean floor, but they have not been found. To find a big deposit might only take an exploration model exclusively designed for gold exploration on the ocean floor.

Jan 1, 1993

By G. Rehder, C. Hensen, P. Linke, J. Bialas, M. Haeckel, W. Weinrebe, K. Wallmann

Research on marine gas hydrate and the methane cycle has a tradition at IFM-GEOMAR. In summer 1996 during a cruise with RV SONNE offshore Oregon (USA) scientists of the former GEOMAR recovered the largest amount of gas hydrate from the seafloor. This discovery stimulated research on marine gas hydrates in Germany and induced funding of scientific programs such as LOTUS and OMEGA with numerous innovative technologies within the special program GEOTECHNOLOGIEN of BMBF and DFG. The primary objectives of ongoing and future research are to achieve a comprehensive knowledge of: • gas hydrate distribution and quantity; • variation and regulation of gas hydrate formation and dissociation as well as of the related fluid flow; • functioning of chemosynthetic communities in methane oxidation, carbonate precipitation and methanotrophy as biological barrier against methane emission and • delineating the escape routes of methane to the hydrosphere and atmosphere.

Aug 24, 2006

By Peter M. Bartlett

The Republic of South Africa ranks among the world leaders in both reserves and production of numerous land-based mineral commodities. Over the last three decades, however, South Africa has also identified several commodities that may exist in commercial quantities in the marine environment. The major targets include 1) placer diamonds; 2) titanium- and zirconium-rich beach sands; 3) sedimentary and concretionary phosphorite and glauconite deposits; 4) manganese nodules; and 5) hydrocarbons. South Africa ranks second in world reserves of diamonds and has potentially enormous sea resources. Diamonds are currently recovered on the Atlantic side from ancient beach gravels in the Northwest Cape Province and from the seabed south of the Orange River to Lamberts Bay. Approximately 100,000 carats (or just 1% of South Africa's total annual production) are produced each year from offshore operations. DeBeers is investing approximately $5 million per year on sea prospecting activities and currently operates three vessels in offshore recovery operations. Diamonds recovered at sea will remain a small percentage of total production because of huge land-based reserves that are mined at a fraction of the cost of seabed operations.

Jan 1, 1986

By Eric J. Foell

Recognizing that the planned commercial exploitation of polymetallic nodules in the deep sea should be accompanied by environmental studies in order to protect this largest and least understood ecosystem of our planet, the German Ministry for Research and Technology has since 1989 funded a longterm and large-scale disturbance-recolonization (DISCOL) experiment in the abyssal Peru Basin of the equatorial South Pacific Ocean. The circular study site is located at 4150m depths and encompasses about 10km2 of relatively flat, heavily sedimented sea floor with low (< 15%) nodule coverage near an existing German nodule mining exploration license area. The RV SONNE, a large and well-equipped multi-purpose research vessel, served as platform for all environmental cruises conducted to date. The initial DISCOL expedition (SO-61, Feb.-March 1989) was carried out in two legs. During DISCOL 1/1, a study site was selected, a pre-disturbance baseline assessment was undertaken, and sea floor disruption was begun using the "plow-harrow", a uniquely designed disturber device towed repeatedly across the circular study area. During DISCOL 1/2, disturber deployments continued until the device had created 78 criss-crossing and partially overlapping tracks along which nodules were essentially plowed under while sediment from up to 15cm below the seabed had been turned over and exposed at the surface. In addition to the obvious within disturber track impacts, sediment mobilized by plowing drifted off with the prevailing near-bottom current and redeposited downstream, blanketing nearby areas not directly disturbed. Immediately after the disturbance phase, an initial post-impact sampling series was performed. The DISCOL Experimental Area (DEA) was revisited about six months (DISCOL 2, SO-64, Sept. 1989), three years (DISCOL 3, SO-77, Feb. 1992), and seven years (ATESEPP SO-106, Jan.-March 1996) after disturbance to collect further post-impact samples, monitor changes in the benthic community and follow the recolonization process. In addition to benthic community studies, plankton investigations were initiated during the third DISCOL cruise (SO-77) and continued during three further cruises (SO-78, SO-79 and SO-80/2) in 1992.

Jan 1, 1996

By J. Robert Woolsey

A unique concept for a self-cleaning filter system has been designed and constructed which utilizes acoustic energy, coupled hydraulically with a subject liquid media, and a fine mesh screen to perform the following: 1. separation of solid suspended particles from a host liquid through the breakdown of surface tension; 2. enhanced filtration of liquid fraction from the solids fraction to specified limits, retaining a specified size range of solids, and; 3. continuous cleaning of screen, preventing screen blinding and promoting a continuous filtration process. The concept is the product of a cooperative program between the Marine Minerals Technology Center, Continental Shelf Division, and the Moscow State Mining University. The physical principals involved in the separation, filtration, and screen cleaning processes primarily relate to the characteristics and properties of the applied acoustic energy and the influence of this energy on the solids/liquid mixture. The acoustic energy introduced to, and acting on and throughout, the whole volume of the solids/liquid mixture, within the vessel body at any given time induces hydraulic pressure waves, which may be further described in simplest form as positive and negative semiperiods (which may or may not be equal in amplitude or period) of the basic wave forms. The processes involved may be considered in two phases. The first phase relates to the process of separation in which the acoustically induced force of acceleration manifests as vibro-agitation (thresh- old of cavitation) and possibly cavitation is the primary factor in the breakdown of surface tension between the solid particles and suspending liquid; i.e. water. In the case of compressible organic solids, the separation of liquid by squeezing may also be a factor.

Jan 1, 1994

By Valcana Stoyanova

Data and information for this study were collected in June-July 2009 onboard the RV Yuzhmorgeologiya in the area covers about 7000 km2 in the eastern part of the CCFZ between 10º05? - 10º55?N and 119º25? ? 121º08?W. In accordance with the IOM research program the cruise was intend to acquire both geological and environmental data and information necessary for delineation of nodule deposits and also data for identification of the baseline of benthic ecosystem. Having implementation of its 15-year plan of work for exploration under the contract with ISA, current activities of IOM were focused on nodule fields within prime areas that could be mined in the future. Bottom photographs obtained by towed deep-sea vehicle NEPTUN along 6 profiles with common length about 300 km (Fig. 1). In total, about 11,500 digital photographs (what cover approximately 40,000 m2 of the ocean floor) were analyzed for assessment of nodule coverage and investigation of megafauna (animals, visible in photographs, the dimension more than 2 cm). The giant single-cell organisms Xenophyophorida were the most multiple animals in seabed photographs. Their number on the site area averaged 1187 ind/ha. However, the vertical camera position does not allow counting all xenophyophorids, therefore their valid number is represented 10 times more. According to all available information these protozoans play the relevant role in assemblage of deep-water environment, giving for other animal groups an [ ] additional source of nutrition and a substratum for settlement and attachment. The ophiuroids are found in assemblage with xenophyophorids in many cases, standing on a sediment at their base.

Jan 1, 2010

By Kira Mizell, James R. Hein

Ferromanganese (FeMn) crusts form by precipitation of iron and manganese oxides from seawater onto a rock substrate and are therefore considered hydrogenetic in origin. Diagenesis does occur however, through the process of phosphatization. During phosphatization, abundant dissolved phosphate in seawater replaces carbonate in the detrital fraction as well as directly precipitates within the FeMn matrix as carbonate fluorapatite (CFA). This process is likely accompanied by the partial dissolution or replacement of the oxide phases [1]. As a result of these diagenetic processes, trace elements adsorbed on the oxides are released and can either be depleted or enriched in the phosphatized FeMn crust layers. Pb, for example, has been shown in sequential leaching experiments to associate with the iron oxyhydroxide (FeOOH) phase in purely hydrogenetic layers, while >95% of Pb in phosphatized crust layers is found in the CFA fraction [2, 3]. However, previous sequential leaching studies analyzed bulk layers of phosphatized crusts and only a few crusts, from the Pacific Ocean. Here we present concentration data for Pb and other trace elements in the CFA fraction leached from thin stratigraphic intervals of the phosphatized portion of FeMn crusts from the Pacific and Atlantic oceans to confirm consistency of trace metal association with CFA both throughout the phosphatized section and in two ocean basins. The Pb and trace element concentration data from this study will also be compared with data from non-phosphatized crusts from the global ocean. We can then determine the effect of phosphatization on the concentration of Pb and other elements of greater economic interest in FeMn crusts, specifically whether there is overall enrichment, depletion, or possibly even phase transfer of each metal in the phosphatized layers.

Jan 1, 2018

Ancient volcanogenic Cu-Zn-Pb-Ag-Au massive sulfide ores commonly have associated with them along strike and in the immediate hanging wall a distinctive sediment that is thin, usually cherty and metal enriched, and generally referred to as an "exhalite horizon" or "tuffaceous exhalite". Typical examplks include the 13 Ma tetsusekiei of the Kuroko deposits of Japan (Kalogeropoulos and Scott, 1983, Econ. Geol.) and the 2700 Ma contact tuffs of Noranda, Canada (Kalogeropoulos and Scott, 1989, Can. J. Earth Sci.) and Key Tuffite of Mattagami, Canada (Liaghat and McLean, 1992, Explor. Min. Geol.). Attempts to use trace element distributions as lithogeochemical guides to ore have been largely unsuccessful. Exhalites have been considered to be the products of seafloor hydrothermal activity that is peripheral to the main ore-producing vents. However, large actively-forming polyrnetallic sulfide deposits at the Explorer mid-ocean basalt spreading ridge (1 850 m depth) in the NE Pacific and the eastern Manus back-arc dacitic spreading center (1650 m depth) in the western Pacific have demonstrated that the exhalite horizons are more likely produced by fallout of particulates from the main hydrothermal plume. In a typical hydrothermal plume, grains of >27 µm represent up to 97% of the mass (although only 2% of the population) of the particulates and are calculated by Stokes equations to fall from the plume to the seafloor within a few krn of their source. The particles are primarily composed of anhydrite, barite, amorphous silica, iron oxyhydroxides and metal sulfides and oxides. Plumes are subject to bottom currents which push them in preferred directions, just like smoke plumes in the atmosphere are subject to the vagaries of wind direction. Bottom currents in the deep ocean can be 50 m/min or

Jan 1, 1993

By Fred C. Dobbs

To effectively manage the potential environmental impacts of deep-sea mining of manganese nodules, we need to know substantially more about the effects of sediment redeposition on abyssal communities and the time scales of recovery from such effects. As an initial step towards a predictive understanding of mining impacts on abyssal benthos, we are conducting a series of biological studies within the framework of the Benthic Impact Experiment (BIE). Mining operations will cause resuspension of sediments across extensive areas of the abyssal Pacific Ocean. The resultant plumes likely will produce redeposition layers, ranging from a few sediment grains in thickness to > 1 cm, over thousands of square kilometers of the seafloor. The impact of such redeposition on abyssal benthic communities is exceedingly difficult to predict. While there has been speculation that redeposition of 1 mm or less will exert deleterious effects, there has been very little testing, and the BIE will provide the first in situ test of redeposition impacts. In a series of cruises before and after controlled resedimentation, we are collecting biological samples to determine the undisturbed state of the ecosystem, the immediate effects of disturbance, and the time-course of recovery resulting from quantified levels of resedimentation.

Jan 1, 1992

By Tobias Hens, Andrew Frierdich, Joël Brugger

The rapid advancement of green technologies in recent years is closely tied to an ever- increasing demand for raw materials. Innovative forms of zero-emission transportation and sustainable power generation will require a variety of traditional metals such as Ni and Co, but also many non-traditional metals (e.g., REY). Many of these elements are known to be highly enriched in deep-sea ferromanganese (Fe-Mn) nodules and crusts. However, unlocking these metals from their deposits through metal processing is – aside from deposit exploration and production – expected to be a critical component that will affect the overall economics of the marine mining value chain. Hence, research and development of tailored metal processing solutions which can target specific metals of interest in Fe-Mn nodules and crusts, is required. Dynamic mineral recrystallization (DMR) of Fe-Mn oxide phases is a geochemical process that may have notable potential for hydrometallurgical applications. We have recently demonstrated that Ni can effectively be cycled between deep-sea Fe-Mn nodules and crusts and solutions through dynamic mineral recrystallization. DMR occurs in nature as abiotic background process during biogeochemical Mn cycling when dissolved Mn(II) is in direct contact with Mn oxides. Trace metals which are incorporated in the Mn host phases, are cycled between solid phase and solution via coupled dissolution (trace metal release) – reprecipitation (trace metal incorporation) mechanisms.

Jan 1, 2018