The rare earth elements（REE） composition of the polymetallic crusts and nodules obtained from the South China Sea（SCS） were analyzed through inductively coupled plasma mass spectrometry.Results revealed great diff...The rare earth elements（REE） composition of the polymetallic crusts and nodules obtained from the South China Sea（SCS） were analyzed through inductively coupled plasma mass spectrometry.Results revealed great differences in the REE abundances（∑REE） of the SCS polymetallic crusts and nodules; the crusts show the highest ∑REE, whereas the nodules exhibit the lowest ∑REE. The similarity in their NASC-normalized patterns, the enriched light REE（LREE）, the markedly positive Ce anomaly（δCe）, and the non-or weakly positive Eu anomaly（δEu）, suggest that the polymetallic crusts and nodules are of hydrogenetic origin. Moreover, the REE contents and their relevant parameters are quite different among the various layers of the crusts and nodules, which probably results from the different marginal sea environments and mineral assemblages of the samples. The growth profiles of the SCS polymetallic crusts and nodules reveal the tendency ∑REE and δCe to slightly increase from the outer to the inner layers, suggesting that the growth environments of these samples changed smoothly from an oxidizing to a relatively reducing environment; in addition, the crust ST1 may have experienced a regressive event（sea-level change） during its growth, although the REE composition of the seawater remained relatively stable. On the basis of the regional ∑REE distribution in the SCS crusts and nodules,the samples collected near the northern margin were influenced by terrigenous material more strongly compared with the other samples, and the REE contents are relatively low. Therefore, the special geotectonic environment is a significant factor influencing the abundance of elements, including REE and other trace elements. Compared with the oceanic seamount crusts and deep-sea nodules from other oceans,the SCS polymetallic crusts and nodules exhibit special REE compositions and shale-normalized patterns, implying that the samples are of marginal sea-type Fe-Mn sedimentary deposits, which are strongly affected by the epicontinental environment, and that they grew in a more oxidative seawater environment. This analysis indicates that the oxidized seawater environment and the special nano property of their Fe-Mn minerals enrich the REE adsorption.展开更多
Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South C...Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South China Sea （SCS） were determined by using X-ray power diffraction （XRD）, Raman spectroscopy （RS）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectron spectroscopy （XPS） to systematically investigate and analyze the mineralogical and spectral characteristics of the Fe-Mn minerals. XRD measurements revealed that the SCS polymetallic crusts and nodules were composed of vernadite, quartz, and plagioclase. The nodules also contained todorokite. The Fe-phase minerals of the SCS crusts and nodules were composed of amorphous Fe oxide/hydroxide, and the Mn- and Fe-phases minerals exhibited relatively poor degrees of crystallization. FTIR results showed that the Fe-Mn minerals in the crusts and nodules included a large number of surface hydroxyl groups. These surface hydroxyl groups contained protons that could provide reactive sites for complexation of ore-forming elements in seawater. XPS results indicated that the surfaces of the Fe-Mn minerals mainly contained Fe, Mn, and O. Fe was present in the trivalent oxidation state, while Mn, which may contain several bivalent oxidation state, was present in the tetravalent and trivalent oxidation states. The SCS polymetallic crusts and nodules were compared with Pacific seamount crusts, and results showed that the surface hydroxyl （-OH） groups of the SCS crusts and nodules numbered more than the lattice oxygen （O^2-）. But the lattice oxygen of Pacific seamount crusts numbered more than the surface hydroxyl groups. This characteristic indicated that the degree of crystallization of Fe-Mn minerals from the Pacific Ocean was higher than that of minerals from the South China Sea. Comprehensive studies showed that ore-forming elements in the interface between seawater and the Fe-Mn minerals in the submarine ferromanganese crusts and nodules employed the following enrichment mechanisms： （1） the metal ion complexed with the surface hydroxyl of Fe-Mn minerals to form hydroxyl complexes, which were connected by coordination bonds or stable inner-sphere complexes that exchanged protons on the mineral surfaces; （2） the charged surfaces of the minerals and metal cations formed outer-sphere complexes, which made up the electrostatic double layer, through electrostatic adsorption; and （3） the metal cations isomorphously exchanged the Mn and Fe ions of the mineral lattice structure.展开更多
Polymetallic nodules and cobalt (Co)-rich crusts are enriched in platinum-group elements (PGEs),especially platinum (Pt) and may be important sinks of PGEs.At present,little information is available on PGEs in polymet...Polymetallic nodules and cobalt (Co)-rich crusts are enriched in platinum-group elements (PGEs),especially platinum (Pt) and may be important sinks of PGEs.At present,little information is available on PGEs in polymetallic nodules,and their geochemical characteristics and the causes of PGEs enrichment are unclear.Here PGEs of polymetallic nodules from abyssal basin in the Marcus-Wake Seamount area of the Northwest Pacific Ocean are reported and compared with the published PGEs data of polymetallic nodules and Co-rich crusts in the Pacific.The total PGEs (ΣPGE) content of polymetallic nodules in study area is 258×10^–9) in average,markedly higher than that of Clarion-Clipperton Zone (CCZ) nodules (ΣPGE=127×10^–9) and lower than that of Co-rich crusts in the Marcus-Wake Seamount (ΣPGE=653×10^–9),similar to that of Co-rich crusts in the South China Sea(ΣPGE=252×10^~–9).The CI chondrite-normalized PGEs patterns in different regions of polymetallic nodules and cobalt-rich crusts are highly consistent,with all being characterized by positive Pt and negative Pd anomalies These results,together with those of previous studies,indicate that PGEs in polymetallic nodules and Co-rich crusts are mainly derived directly from seawater.Pt contents of polymetallic nodules from the study area are negatively correlated with water depth,and Pt/ΣPGE ratios in nodules there are also lower than those of the Corich crusts in the adjacent area,indicating that sedimentary water depth and oxygen fugacity of ambient seawater are the possible important controlling factors for Pt accumulation in crusts and nodules.展开更多
: This paper presents a quantitative analysis of the relations of the occurrence of polymetallic nodules with the geochemical actions of microbes in the seawater, pore water and sediments at the bottom of the eastern ...: This paper presents a quantitative analysis of the relations of the occurrence of polymetallic nodules with the geochemical actions of microbes in the seawater, pore water and sediments at the bottom of the eastern Pacific Ocean basin. Emphasis is laid on the relations of the activity intensity and biochemical transformation rate of aerobic bacteria (iron bacteria, Thiobacillus thioparus, halobacteria and manganese—oxidizing bacteria) and anaerobic bacteria (sulphate—reducing bacteria, denitrifying bacteria, Thiobacillus denitrificans) with mineralization. The experimental research on the migration and accumulation of ore-forming elements caused by microbial and chemical actions shows that the microbes have changed the conditions of oxidation and reduction in the system, and their effect on the element precipitation is much stronger than the chemical actions and accelerates the enrichment of Fe and Ma It demonstrates that the microbes can change the environment to promote the accumulation of ore-forming elements, thus leading to indirect mineralization.展开更多
The kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium was investigated in terms of the gas-flow rate, stirring rate, reaction time, reaction temperature and partial pres...The kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium was investigated in terms of the gas-flow rate, stirring rate, reaction time, reaction temperature and partial pressure of oxygen on the ratio of manganese conversion in ocean polymetallic nodules. The category of the rate controlling step was determined. The process of the liquid-phase oxidation reaction can be described by surface chemical reaction-controlled non-reaction shrinking core model(SCM), the apparent activation energy was achieved and the rate equation was put forward. From the equation, it can be concluded that the reaction rate mainly depends on the reaction temperature and the partial pressure of oxygen.展开更多
Manganese minerals in the polymetallic nodules from the Central Pacific Ocean were studied using electron microscopy. The principal Mn minerals, being vernadite and todorokite, exhibit different electron diffraction p...Manganese minerals in the polymetallic nodules from the Central Pacific Ocean were studied using electron microscopy. The principal Mn minerals, being vernadite and todorokite, exhibit different electron diffraction patterns and morphological features. According to its morphological feature, todorokite shows three phases: fibrous, lamellar and lath-shaped. Both vernadite and todorokite are authigenic minerals. While vernadite was mainly precipitated directly from the relevant solution by microbiological oxidation, todorokite was separated from the solution chemically without the help of microbe. Hence, these two minerals show a close genetic relation.展开更多
Non-destructive γ spectrum analyses of 20 polymetallic nodules from the eastern Pacificwere carried out. Numerous nuclides, such as 238U,230Th,226Ra,210Pb,228Ra,228Th,235U,227Ac (or 231 Pa) and 40K were detected. The...Non-destructive γ spectrum analyses of 20 polymetallic nodules from the eastern Pacificwere carried out. Numerous nuclides, such as 238U,230Th,226Ra,210Pb,228Ra,228Th,235U,227Ac (or 231 Pa) and 40K were detected. The count rates of the nuclides in the top or bottom side of nodules facing detector were measured and the ratio R of the count rates of nuclides in the top and the bottom sides was obtained. From counts and ratios, some useful information relating to the growth and movement of the nodules, the source of nuclide and relationship between those and environment can be gotten. A new method for clear distinction between the top and bottom sides of the nodule based on the R value of 226Ra or 210Pb was developed. In addition, one can infer the turnover of nodules according to the R value of 230Th.展开更多
Geotechnical data obtained from the polymetallic nodules investigation in 1994, in combi nation with the historical data concerned, are analyses comprehensively to study sediment types, geotechnical properties, soil ...Geotechnical data obtained from the polymetallic nodules investigation in 1994, in combi nation with the historical data concerned, are analyses comprehensively to study sediment types, geotechnical properties, soil strength and so on, in order to provide bases for design and construction of engineering facilities and the equipments raquired for the polymetallic nodules mining in the future.展开更多
The tectonic setting of the west region of the Reserved Area of the International Seabed Authority is the same as that of China Pioneer Area. They have similar characteristics of topography and nodule distribution. To...The tectonic setting of the west region of the Reserved Area of the International Seabed Authority is the same as that of China Pioneer Area. They have similar characteristics of topography and nodule distribution. To research and analyse the characteristics and control factors of nodule distribution can help the establishment of a geological model and the assessment of the polymetallic nodule resource. From the year of 1991 till 2000 COMRA (China Ocean Mineral Resource Research and Development Association) carried out phase 1 and 2 of the exploration and resource assessment project of polymetallic nodules in China Pioneer Area. The features of topography and geo logy, and the distribution of polymetallic nodules and control factors have been clearly understood. The results show that the formation and types and spatial features of abundance and grade of nodules resulted from several factors, the tectonic features (volcanism and faulting) and seafloor topography play an important role in the geological process of the formation of polymetallic nodules.展开更多
Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the poten...Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.展开更多
Elemental compositions are measured in manganese nodules collected from the Northern Mid-Pacific floor by inductively-coupled plasma atomic emission spectrometry (1CP-AES) and their growth rates are determined by radi...Elemental compositions are measured in manganese nodules collected from the Northern Mid-Pacific floor by inductively-coupled plasma atomic emission spectrometry (1CP-AES) and their growth rates are determined by radiometric methods. The result shows that depth distributions of elements in nodules vary with depth as follows; (i) increase, (ii) decrease and (iii) fluctuation. These internodule variations in elemental compositions are considered to be caused by diffusion and migration of elements in nodules and heterogeneities in textures of nodules. In the present paper, a diffusive model is used to elucidate the inward-increase profile of some elements in nodules. The effective diffusive coefficients are estimated to be of the order of 10-9 cm2/a for Ni, V and Zn in the nodules, which is less than the value reported for radionuclides.展开更多
A large number of nodule minerals exist in the deep sea.Based on the factors of difficulty in shooting,high economic cost and high accuracy of resource assessment,large-scale planned commercial mining has not yet been...A large number of nodule minerals exist in the deep sea.Based on the factors of difficulty in shooting,high economic cost and high accuracy of resource assessment,large-scale planned commercial mining has not yet been conducted.Only experimental mining has been carried out in areas with high mineral density and obvious benefits after mineral resource assessment.As an efficient method for deep-sea mineral resource assessment,the deep towing system is equipped with a visual system for mineral resource analysis using collected images and videos,which has become a key component of resource assessment.Therefore,high accuracy in deep-sea mineral image segmentation is the primary goal of the segmentation algorithm.In this paper,the existing deep-sea nodule mineral image segmentation algorithms are studied in depth and divided into traditional and deep learning-based segmentation methods,and the advantages and disadvantages of each are compared and summarized.The deep learning methods show great advantages in deep-sea mineral image segmentation,and there is a great improvement in segmentation accuracy and efficiency compared with the traditional methods.Then,the mineral image dataset and segmentation evaluation metrics are listed.Finally,possible future research topics and improvement measures are discussed for the reference of other researchers.展开更多
This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indi...This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indian Ocean Basin(CIOB)to address their genetic aspects,classification,growth rate,nature of host sediments and influence of REE in the processes of nodule formation.The nodules from CIOB are mostly either hydrogenetic(metals coming from oxygenated bottom water)and diagenetic(metals coming from suboxic sediment pore water)or a combination of both,depending on the source of supply of metal.However,a number of biogeochemical processes mediate this supply of metals which again changes from time to time,making the nodule growth process highly dynamic.This study suggests that at the initial stage of nodule growth,host sediments do not play much role in controlling the growth processes for which REEs can enter both Mn and Fe oxyhydroxide phases equally.Thus,the bottom water signature is imprinted in these early formed nodules irrespective of their host sediment substrate but with gradual growth and burial in the sediment,the main mode of metal enrichment becomes diagenetic through sediment pore water.This tends to increase the concentration of Mn,Ni and Cu over other elements which are retained in the sediment fraction.Among the REEs,Ce concentration of the nodules shows significant positive anomaly due to variation in redox potential and hence its magnitude can be used to get an idea about the metal enrichment procedure and the genetic type of the nodules.However,based on host sediment only,not much difference is found in the magnitude of Ce anomaly in these nodules.On the other hand,discrimination diagram,based on HFSE and REY chemistry,indicates that most of these nodules are of diagenetic origin under oxic condition with a trend towards hydrogenetic field.Further,the genetic type of the ferromanganese nodules from the CIOB are more effectively differentiated by a combination of their major and trace element concentrations rather than solely based on their REE or HFSE chemistry or host sediment substrate.展开更多
基金financially supported by the National12th Five Year Plan Project(No.DY-125-13-R-05)Natural Sciences Foundation of China(No.40343019.40473024)+2 种基金project from the State Key Laboratory for Mineral Deposits Research in Nanjing University(No.20-15-07)the Project Supported by Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2011)the Fundamental Research Funds for Central Universities(No.121gjc05,091gpy09)
文摘The rare earth elements（REE） composition of the polymetallic crusts and nodules obtained from the South China Sea（SCS） were analyzed through inductively coupled plasma mass spectrometry.Results revealed great differences in the REE abundances（∑REE） of the SCS polymetallic crusts and nodules; the crusts show the highest ∑REE, whereas the nodules exhibit the lowest ∑REE. The similarity in their NASC-normalized patterns, the enriched light REE（LREE）, the markedly positive Ce anomaly（δCe）, and the non-or weakly positive Eu anomaly（δEu）, suggest that the polymetallic crusts and nodules are of hydrogenetic origin. Moreover, the REE contents and their relevant parameters are quite different among the various layers of the crusts and nodules, which probably results from the different marginal sea environments and mineral assemblages of the samples. The growth profiles of the SCS polymetallic crusts and nodules reveal the tendency ∑REE and δCe to slightly increase from the outer to the inner layers, suggesting that the growth environments of these samples changed smoothly from an oxidizing to a relatively reducing environment; in addition, the crust ST1 may have experienced a regressive event（sea-level change） during its growth, although the REE composition of the seawater remained relatively stable. On the basis of the regional ∑REE distribution in the SCS crusts and nodules,the samples collected near the northern margin were influenced by terrigenous material more strongly compared with the other samples, and the REE contents are relatively low. Therefore, the special geotectonic environment is a significant factor influencing the abundance of elements, including REE and other trace elements. Compared with the oceanic seamount crusts and deep-sea nodules from other oceans,the SCS polymetallic crusts and nodules exhibit special REE compositions and shale-normalized patterns, implying that the samples are of marginal sea-type Fe-Mn sedimentary deposits, which are strongly affected by the epicontinental environment, and that they grew in a more oxidative seawater environment. This analysis indicates that the oxidized seawater environment and the special nano property of their Fe-Mn minerals enrich the REE adsorption.
基金The National Natural Science Foundation of China under contract Nos 40473024 and 40343019the research fund from State Key Laboratory for Mineral Deposits Research in Nanjing University under contract No.20-15-07+3 种基金the Investigation and Development of Marine Resources during the 12th Five Year Plan Project under contract No.DY125-13-R-05the Doctoral Program of Higher Education Research Fund under contract Nos 20040558049 and 20120171130005the Project of High Level Talents in Colleges of Guangdong Province(2011)the Fundamental Research Funds for Central Universities under contract Nos 16lgjc11,12lgjc05 and 09lgpy09
文摘Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South China Sea （SCS） were determined by using X-ray power diffraction （XRD）, Raman spectroscopy （RS）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectron spectroscopy （XPS） to systematically investigate and analyze the mineralogical and spectral characteristics of the Fe-Mn minerals. XRD measurements revealed that the SCS polymetallic crusts and nodules were composed of vernadite, quartz, and plagioclase. The nodules also contained todorokite. The Fe-phase minerals of the SCS crusts and nodules were composed of amorphous Fe oxide/hydroxide, and the Mn- and Fe-phases minerals exhibited relatively poor degrees of crystallization. FTIR results showed that the Fe-Mn minerals in the crusts and nodules included a large number of surface hydroxyl groups. These surface hydroxyl groups contained protons that could provide reactive sites for complexation of ore-forming elements in seawater. XPS results indicated that the surfaces of the Fe-Mn minerals mainly contained Fe, Mn, and O. Fe was present in the trivalent oxidation state, while Mn, which may contain several bivalent oxidation state, was present in the tetravalent and trivalent oxidation states. The SCS polymetallic crusts and nodules were compared with Pacific seamount crusts, and results showed that the surface hydroxyl （-OH） groups of the SCS crusts and nodules numbered more than the lattice oxygen （O^2-）. But the lattice oxygen of Pacific seamount crusts numbered more than the surface hydroxyl groups. This characteristic indicated that the degree of crystallization of Fe-Mn minerals from the Pacific Ocean was higher than that of minerals from the South China Sea. Comprehensive studies showed that ore-forming elements in the interface between seawater and the Fe-Mn minerals in the submarine ferromanganese crusts and nodules employed the following enrichment mechanisms： （1） the metal ion complexed with the surface hydroxyl of Fe-Mn minerals to form hydroxyl complexes, which were connected by coordination bonds or stable inner-sphere complexes that exchanged protons on the mineral surfaces; （2） the charged surfaces of the minerals and metal cations formed outer-sphere complexes, which made up the electrostatic double layer, through electrostatic adsorption; and （3） the metal cations isomorphously exchanged the Mn and Fe ions of the mineral lattice structure.
基金China Ocean Mineral Resources R&D Association(COMRA)Project under contract Nos DY135-C1-1-05,DY135-N1-1-06 and DY135-C1-1-02the Scientific Research Fund of the Second Institute of Oceanography,MNR under contract No.JT1304。
文摘Polymetallic nodules and cobalt (Co)-rich crusts are enriched in platinum-group elements (PGEs),especially platinum (Pt) and may be important sinks of PGEs.At present,little information is available on PGEs in polymetallic nodules,and their geochemical characteristics and the causes of PGEs enrichment are unclear.Here PGEs of polymetallic nodules from abyssal basin in the Marcus-Wake Seamount area of the Northwest Pacific Ocean are reported and compared with the published PGEs data of polymetallic nodules and Co-rich crusts in the Pacific.The total PGEs (ΣPGE) content of polymetallic nodules in study area is 258×10^–9) in average,markedly higher than that of Clarion-Clipperton Zone (CCZ) nodules (ΣPGE=127×10^–9) and lower than that of Co-rich crusts in the Marcus-Wake Seamount (ΣPGE=653×10^–9),similar to that of Co-rich crusts in the South China Sea(ΣPGE=252×10^~–9).The CI chondrite-normalized PGEs patterns in different regions of polymetallic nodules and cobalt-rich crusts are highly consistent,with all being characterized by positive Pt and negative Pd anomalies These results,together with those of previous studies,indicate that PGEs in polymetallic nodules and Co-rich crusts are mainly derived directly from seawater.Pt contents of polymetallic nodules from the study area are negatively correlated with water depth,and Pt/ΣPGE ratios in nodules there are also lower than those of the Corich crusts in the adjacent area,indicating that sedimentary water depth and oxygen fugacity of ambient seawater are the possible important controlling factors for Pt accumulation in crusts and nodules.
基金This paper is based on the results of project No. 49472111 of the National Natural Science Foundation of China and a major project of science and technology of the "Eighth Five-Year Plan" (1991-1995) as well as marine investigations of cruises DY85-1 and DY85-3.
文摘: This paper presents a quantitative analysis of the relations of the occurrence of polymetallic nodules with the geochemical actions of microbes in the seawater, pore water and sediments at the bottom of the eastern Pacific Ocean basin. Emphasis is laid on the relations of the activity intensity and biochemical transformation rate of aerobic bacteria (iron bacteria, Thiobacillus thioparus, halobacteria and manganese—oxidizing bacteria) and anaerobic bacteria (sulphate—reducing bacteria, denitrifying bacteria, Thiobacillus denitrificans) with mineralization. The experimental research on the migration and accumulation of ore-forming elements caused by microbial and chemical actions shows that the microbes have changed the conditions of oxidation and reduction in the system, and their effect on the element precipitation is much stronger than the chemical actions and accelerates the enrichment of Fe and Ma It demonstrates that the microbes can change the environment to promote the accumulation of ore-forming elements, thus leading to indirect mineralization.
文摘The kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium was investigated in terms of the gas-flow rate, stirring rate, reaction time, reaction temperature and partial pressure of oxygen on the ratio of manganese conversion in ocean polymetallic nodules. The category of the rate controlling step was determined. The process of the liquid-phase oxidation reaction can be described by surface chemical reaction-controlled non-reaction shrinking core model(SCM), the apparent activation energy was achieved and the rate equation was put forward. From the equation, it can be concluded that the reaction rate mainly depends on the reaction temperature and the partial pressure of oxygen.
文摘Manganese minerals in the polymetallic nodules from the Central Pacific Ocean were studied using electron microscopy. The principal Mn minerals, being vernadite and todorokite, exhibit different electron diffraction patterns and morphological features. According to its morphological feature, todorokite shows three phases: fibrous, lamellar and lath-shaped. Both vernadite and todorokite are authigenic minerals. While vernadite was mainly precipitated directly from the relevant solution by microbiological oxidation, todorokite was separated from the solution chemically without the help of microbe. Hence, these two minerals show a close genetic relation.
基金This study was supported by the National Scientific Technological Project of China in the "Ninth-Five Year Plan" under contract No. DY95 - 02 - 15.
文摘Non-destructive γ spectrum analyses of 20 polymetallic nodules from the eastern Pacificwere carried out. Numerous nuclides, such as 238U,230Th,226Ra,210Pb,228Ra,228Th,235U,227Ac (or 231 Pa) and 40K were detected. The count rates of the nuclides in the top or bottom side of nodules facing detector were measured and the ratio R of the count rates of nuclides in the top and the bottom sides was obtained. From counts and ratios, some useful information relating to the growth and movement of the nodules, the source of nuclide and relationship between those and environment can be gotten. A new method for clear distinction between the top and bottom sides of the nodule based on the R value of 226Ra or 210Pb was developed. In addition, one can infer the turnover of nodules according to the R value of 230Th.
文摘Geotechnical data obtained from the polymetallic nodules investigation in 1994, in combi nation with the historical data concerned, are analyses comprehensively to study sediment types, geotechnical properties, soil strength and so on, in order to provide bases for design and construction of engineering facilities and the equipments raquired for the polymetallic nodules mining in the future.
文摘The tectonic setting of the west region of the Reserved Area of the International Seabed Authority is the same as that of China Pioneer Area. They have similar characteristics of topography and nodule distribution. To research and analyse the characteristics and control factors of nodule distribution can help the establishment of a geological model and the assessment of the polymetallic nodule resource. From the year of 1991 till 2000 COMRA (China Ocean Mineral Resource Research and Development Association) carried out phase 1 and 2 of the exploration and resource assessment project of polymetallic nodules in China Pioneer Area. The features of topography and geo logy, and the distribution of polymetallic nodules and control factors have been clearly understood. The results show that the formation and types and spatial features of abundance and grade of nodules resulted from several factors, the tectonic features (volcanism and faulting) and seafloor topography play an important role in the geological process of the formation of polymetallic nodules.
基金supported by the National Natural Science Foundation of China(Nos.52225107,U2106224,U1906234,51822904,and U1706223)the Fundamental Research Funds for the Central Universities(No.202041004)
文摘Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.
文摘Elemental compositions are measured in manganese nodules collected from the Northern Mid-Pacific floor by inductively-coupled plasma atomic emission spectrometry (1CP-AES) and their growth rates are determined by radiometric methods. The result shows that depth distributions of elements in nodules vary with depth as follows; (i) increase, (ii) decrease and (iii) fluctuation. These internodule variations in elemental compositions are considered to be caused by diffusion and migration of elements in nodules and heterogeneities in textures of nodules. In the present paper, a diffusive model is used to elucidate the inward-increase profile of some elements in nodules. The effective diffusive coefficients are estimated to be of the order of 10-9 cm2/a for Ni, V and Zn in the nodules, which is less than the value reported for radionuclides.
基金This work was supported in part by the National Science Foundation Project of P.R.China under Grant No.52071349,No.U1906234partially supported by the Open Project Program of Key Laboratory ofMarine Environmental Survey Technology and Application,Ministry of Natural Resource MESTA-2020-B001+1 种基金Young and Middle-aged Talents Project of the State Ethnic Affairs Commission,the Crossdisciplinary Research Project of Minzu University of China(2020MDJC08)the Graduate Research and Practice Projects of Minzu University of China(SZKY2021039).
文摘A large number of nodule minerals exist in the deep sea.Based on the factors of difficulty in shooting,high economic cost and high accuracy of resource assessment,large-scale planned commercial mining has not yet been conducted.Only experimental mining has been carried out in areas with high mineral density and obvious benefits after mineral resource assessment.As an efficient method for deep-sea mineral resource assessment,the deep towing system is equipped with a visual system for mineral resource analysis using collected images and videos,which has become a key component of resource assessment.Therefore,high accuracy in deep-sea mineral image segmentation is the primary goal of the segmentation algorithm.In this paper,the existing deep-sea nodule mineral image segmentation algorithms are studied in depth and divided into traditional and deep learning-based segmentation methods,and the advantages and disadvantages of each are compared and summarized.The deep learning methods show great advantages in deep-sea mineral image segmentation,and there is a great improvement in segmentation accuracy and efficiency compared with the traditional methods.Then,the mineral image dataset and segmentation evaluation metrics are listed.Finally,possible future research topics and improvement measures are discussed for the reference of other researchers.
基金the support of CSIR Senior Research Fellowship,Indiaa part of the“Polymetallic Nodule:Survey and Exploration”project(GAP 2175)supported by Ministry of Earth Sciences,Govt.of India.This is NIO's contribution No.6633。
文摘This study presents new major,trace and REE data for thirty-five ferromanganese nodules recovered from areas representing three different sediment types(siliceous,red clay and their transition zone)in the Central Indian Ocean Basin(CIOB)to address their genetic aspects,classification,growth rate,nature of host sediments and influence of REE in the processes of nodule formation.The nodules from CIOB are mostly either hydrogenetic(metals coming from oxygenated bottom water)and diagenetic(metals coming from suboxic sediment pore water)or a combination of both,depending on the source of supply of metal.However,a number of biogeochemical processes mediate this supply of metals which again changes from time to time,making the nodule growth process highly dynamic.This study suggests that at the initial stage of nodule growth,host sediments do not play much role in controlling the growth processes for which REEs can enter both Mn and Fe oxyhydroxide phases equally.Thus,the bottom water signature is imprinted in these early formed nodules irrespective of their host sediment substrate but with gradual growth and burial in the sediment,the main mode of metal enrichment becomes diagenetic through sediment pore water.This tends to increase the concentration of Mn,Ni and Cu over other elements which are retained in the sediment fraction.Among the REEs,Ce concentration of the nodules shows significant positive anomaly due to variation in redox potential and hence its magnitude can be used to get an idea about the metal enrichment procedure and the genetic type of the nodules.However,based on host sediment only,not much difference is found in the magnitude of Ce anomaly in these nodules.On the other hand,discrimination diagram,based on HFSE and REY chemistry,indicates that most of these nodules are of diagenetic origin under oxic condition with a trend towards hydrogenetic field.Further,the genetic type of the ferromanganese nodules from the CIOB are more effectively differentiated by a combination of their major and trace element concentrations rather than solely based on their REE or HFSE chemistry or host sediment substrate.
