Deep-sea Ferromanganese Crusts Research Articles

Systmatic Analysis of Magnetic Monopoles History, Current Research, and Advances

Magnetic monopoles, first posited by Paul Dirac in 1931, are hypothetical particles that carry a single magnetic charge, unlike ordinary dipoles which have both a north and south pole. These particles would introduce a striking symmetry to Maxwell’s equations of electromagnetism and could provide a compelling explanation for the quantization of electric charge, a key aspect of our understanding of particle physics. Dirac’s theoretical framework laid the groundwork for subsequent exploration of monopoles, inspiring decades of experimental efforts to detect them. These efforts have included searches for remnants of magnetic monopoles in ancient deep-sea ferromanganese crusts and attempts to produce them in advanced particle accelerator experiments, such as those conducted at CERN. Recent breakthroughs in condensed matter physics, particularly in the study of spin ice materials, as well as the creation of synthetic Dirac monopoles in Bose-Einstein condensates, have generated new avenues for understanding their properties and potential behavior. Although magnetic monopoles have not yet been observed directly, ongoing research continues to refine theoretical models and experimental techniques, keeping the search at the frontier of modern physics. The pursuit of monopoles remains significant, especially in the context of advancing toward a unified theory of fundamental forces that underpins the universe.

Assessment of acoustic backscatter intensity surveying on deep-sea ferromanganese crust: Constraints from Weijia Guyot, western Pacific Ocean

Near-bottom observation data from the manned deep submersible Jiaolong with high-precision underwater positioning data from Weijia Guyot, Magellan Seamounts in the Western Pacific Ocean are reported. Three substrate types were identified: Sediment, ferromanganese crust, and ferromanganese crust with a thin cover of sediment. The ferromanganese crusts show clear zoning and their continuity is usually disturbed by sediments on areas of the mountainside with relatively gentle slope gradients. The identified substrate spatial distributions correspond to acoustic backscatter intensity data, with regions of high intensity always including crust development and regions of low intensity always having sediment. Therefore, acoustic backscatter intensity surveying appears useful in the delineation and evaluation of crust resources, although further more work is needed to develop a practicable methodology.

Heterogeneity of Microbial Communities on Deep-Sea Ferromanganese Crusts in the Takuyo-Daigo Seamount.

Rock outcrops of aged deep-sea seamounts are generally covered with Fe and Mn oxides, known as ferromanganese (Fe–Mn) crusts. Although the presence of microorganisms in Fe–Mn crusts has been reported, limited information is currently available on intra- and inter-variations in crust microbial communities. Therefore, we collected several Fe–Mn crusts in bathyal and abyssal zones (water depths of 1,150–5,520 m) in the Takuyo-Daigo Seamount in the northwestern Pacific, and examined microbial communities on the crusts using culture-independent molecular and microscopic analyses. Quantitative PCR showed that microbial cells were abundant (106–108 cells g−1) on Fe–Mn crust surfaces through the water depths. A comparative 16S rRNA gene analysis revealed community differences among Fe–Mn crusts through the water depths, which may have been caused by changes in dissolved oxygen concentrations. Moreover, community differences were observed among positions within each Fe–Mn crust, and potentially depended on the availability of sinking particulate organic matter. Microscopic and elemental analyses of thin Fe–Mn crust sections revealed the accumulation of microbial cells accompanied by the depletion of Mn in valleys of bumpy crust surfaces. Our results suggest that heterogeneous and abundant microbial communities play a role in the biogeochemical cycling of Mn, in addition to C and N, on crusts and contribute to the extremely slow growth of Fe–Mn crusts.

Archaeal and bacterial communities in deep-sea hydrogenetic ferromanganese crusts on old seamounts of the northwestern Pacific.

Deep-sea ferromanganese crusts are found ubiquitously on the surface of seamounts of the world’s oceans. Considering the wide distribution of the crusts, archaeal and bacterial communities on these crusts potentially play a significant role in biogeochemical cycling between oceans and seamounts; however little is known about phylogenetic diversity, abundance and function of the crust communities. To this end, we collected the crusts from the northwest Pacific basin and the Philippine Sea. We performed comprehensive analysis of the archaeal and bacterial communities of the collected crust samples by culture-independent molecular techniques. The distance between the sampling points was up to approximately 2,000 km. Surrounding sediments and bottom seawater were also collected as references near the sampling points of the crusts, and analyzed together. 16S rRNA gene analyses showed that the community structure of the crusts was significantly different from that of the seawater. Several members related to ammonia-oxidizers of Thaumarchaeota and Betaproteobacteria were detected in the crusts at most of all regions and depths by analyses of 16S rRNA and amoA genes, suggesting that the ammonia-oxidizing members are commonly present in the crusts. Although members related to the ammonia-oxidizers were also detected in the seawater, they differed from those in the crusts phylogenetically. In addition, members of uncultured groups of Alpha-, Delta- and Gammaproteobacteria were commonly detected in the crusts but not in the seawater. Comparison with previous studies of ferromanganese crusts and nodules suggests that the common members determined in the present study are widely distributed in the crusts and nodules on the vast seafloor. They may be key microbes for sustaining microbial ecosystems there.

Stellar astrophysics: Supernovae in the neighbourhood.

Detailed measurements of radioisotopes in deep-sea deposits, plus modelling of how they reached Earth, indicate that many supernovae have occurred near enough to have potentially influenced evolution. See Letters p.69 & p.73 Twenty years ago it was suggested that nearby supernova explosions could leave their mark here on Earth in the shape of geological isotope anomalies caused by direct deposition of debris or through cosmic-ray spallation in the atmosphere. So it proved, with the emergence of iron-60, found in deep-sea ferromanganese crusts, as a supernova indicator. Two papers in this issue add further detail to the picture, and suggest there have been multiple supernovae within a few hundred light years, over the past few million years. Anton Wallner et al. report that the deep-sea 60Fe signal is global, extended in time and of interstellar origin from multiple events. Their results reveal 60Fe interstellar influxes onto Earth 1.7–3.2 and 6.5–8.7 million years ago. Dieter Breitschwerdt et al. report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The 60Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago, and the second about 1.5 million years ago at 9.2 and 8.8 solar masses, respectively.

AMS measurement of 53Mn and its initial application at CIAE

The determination of cosmogenic 53Mn in terrestrial archives has important applications, such as burial ages, exposure age and erosion rates. Accelerator mass spectrometry (AMS) is the most sensitive technique to detect minute amounts of 53Mn. 53Mn measurements were developed at the China Institute of Atomic Energy (CIAE) using the ΔE-Q3D equipped AMS system. This approach was recently optimized with the goal to reach the sensitivity required for AMS measurements of 53Mn in deep-sea ferromanganese crust (DSFC) samples. Based on these improvements of sample preparation, current beam transmission and so on, 53Mn in two samples of DSFC was measured by AMS. The ratios of 53Mn/Mn corresponding to an age of 3.77±0.42 and 13.73±2.74Ma by 129I dating method are (5.01±2.15)×10−13 and (1.90±0.96)×10−13. The ratios are close to the experimental reference values, deduced from the previous research. The experimental progress, performances and results are presented in this contribution.

The measurement of 129I in ferromanganese crusts and aerosol samples with AMS at CIAE

The determination of long-lived nuclide 129I in terrestrial formations has many important applications. The AMS measurement method of 129I has been set up for many years at China Institute of Atomic Energy (CIAE). For further exploring the potential applications of 129I, samples of Deep Sea Ferromanganese Crusts (DSFC) and aerosol were analyzed by Accelerator Mass Spectrometry (AMS). The results show that 129I is not only a good tool for dating, but also an ideal nuclide for nuclear safety monitoring. The newest experimental progress and the main results are detailed in this presentation.

Deep-sea Fe-Mn Crusts from the Northeast Atlantic Ocean: Composition and Resource Considerations

Eighteen deep-sea ferromanganese crusts (Fe-Mn crusts) from 10 seamounts in the northeast Atlantic were studied. Samples were recovered from water depths of ∼1,200 to ∼4,600 m from seamounts near Madeira, the Canary and Azores islands, and one sample from the western Mediterranean Sea. The mineralogical and chemical compositions of the samples indicate that the crusts are typical continental margin, hydrogenetic Fe-Mn crusts. The Fe-Mn crusts exhibit a Co + Cu + Ni maximum of 0.96 wt%. Platinum-group element contents analyzed for five samples showed Pt contents from 153 to 512 ppb. The resource potential of Fe-Mn crusts within and adjacent to the Portuguese Exclusive Economic Zone (EEZ) is evaluated to be comparable to that of crusts in the central Pacific, indicating that these Atlantic deposits may be an important future resource.

Discovery prospects for a supernova signature of biogenic origin

Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of 60Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite (Fe 3O 4) microfossils produced by magnetotactic bacteria extant at the time of the Earth-supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using estimates for the terrestrial supernova 60Fe flux, combined with our empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the 60Fe fraction as 60Fe/Fe ≈ 3.6 × 10 −15. This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry capabilities. The implication is that a biogenic signature of this cosmic event is detectable in the Earth’s fossil record.

深海底鉱物資源の製錬におけるバイオリーチングの応用

Because of the depletion of terrestrial mineral resources, the recovery of base and precious metals from deep-sea mineral resources is sure to become of significant importance. Although pyro- and hydrometallurgical processes have been developed to recover valuable metals from deep-seabed ferromanganese mineral resources, another possibility is the application of biohydrometallurgical processes. The use of microorganisms to facilitate the extraction of metals from minerals is referred to as which is an economical and environmentally friendly process. The bioleaching of terrestrial sulfide minerals has developed into a successful and expanding area of biotechnology: commercial heap bioleaching is typically used for low-grade sulfide ores of 0.5% or less Cu, and commercial tank bioleaching is used mostly in the pretreatment of gold ores. The bioleaching technologies can be applied to metal extraction from deep-sea hydrothermal sulfides as well as terrestrial sulfide minerals. However, little attention has been given to the bioleaching of oxide minerals such as ferromanganese crusts and nodules. A new bioleaching system has been more recently proposed for ferromanganese crusts and nodules, in which dissolved Fe (II) is microbially produced by the Fe (III) -reducing bacterium and simultaneously used to extract Co, Ni and Mn under anaerobic conditions. The proposed bioleaching is a potentially attractive method, with good metal extractions taking only 7 hours of batch operation at room temperature and neutral pH. Further research should be planned to clarify the bioleaching behavior of other elements such as rare earths, Ti and Mo from deep-sea ferromanganese crusts. It can be concluded that bioleaching is an attractive processing route to recover valuable metals from deep-seabed mineral resources.

Chemical procedure for extracting 129I, 60Fe and 26Al from marine sediments: Prospects for detection of a ∼2.8 My old supernova

For the past three years, we have been developing a procedure to measure carrier-free 129I/I in gram size quantities of marine sediments containing microgram quantities of iodine. Potential applications involve dating of old (>10My) sediments and the detection of 129I (t1/2=15.7My) from a purported supernova (SN) explosion ∼2.8 million years ago, that has been inferred from a 60Fe (t1/2=1.5My) signal in a deep-sea ferromanganese crust [K. Knie, G. Korschinek, T. Faestermann, E.A. Dorfi, G. Rugel, A. Wallner, Phys. Rev. Lett. 93 (2004) 171103]. The procedure consists in washing the sediment with a NH2OH·HCl–HOAc mixture, extraction of iodine from the organic phase with TMAH, separation and purification using anion-exchange chromatography, and coprecipitation as AgI–Ag2O. We realized the washing step, which extracts authigenic iron and aluminum, could also be used to measure 60Fe/56Fe and 26Al/27Al in this phase of the same sediment sample. We outline here the chemical procedures developed, and briefly comment on their possible application to the supernova problem. We also point out a large discrepancy between the theoretically calculated 129I/127I ratio in pre-anthropogenic marine sediments, and that derived from experimental measurements.

F60eAnomaly in a Deep-Sea Manganese Crust and Implications for a Nearby Supernova Source

A nearby supernova (SN) explosion in the past can be confirmed by the detection of radioisotopes on Earth that were produced and ejected by the SN. We have now measured a well resolved time profile of the 60Fe concentration in a deep-sea ferromanganese crust and found a highly significant increase 2.8 Myr ago. The amount of 60Fe is compatible with the deposition of ejecta from a SN at a distance of a few 10 pc. The well defined time of the SN explosion makes it possible to search for plausible correlations with other events in Earth's history.

Development of a very sensitive AMS method for the detection of supernova-produced longliving actinide nuclei in terrestrial archives

For a search of supernova-produced actinide atoms in terrestrial archives, techniques for measuring minute amounts of atoms of actinides with AMS have been developed at the Munich tandem accelerator laboratory. A large analyzing magnet has been installed, able to bend even the heavy transuranic ions at the high energies achievable with our MP tandem. The final detector is a time-of-flight and a multiple energy loss measurement which allows a nearly background-free detection of individual actinides like 244Pu. An efficient chemical preparation method has been developed for the extraction of small amounts of plutonium from samples up to nearly 1 kg. Furthermore, the preparation of sputter cathodes, containing the final sample material, was optimized for high yields of negative molecules in the Cs-sputter ion source. The first search for supernova-originated 244Pu in a deep sea ferromanganese crust has already been carried out.

Separation of Lanthanide Series Elements in Marine Fe-Mn Crusts by Ion-Exchange Chromatography and Determination by ICP/AES

Abstract A method is described for the separation of lanthanide series elements (REE) from major matrix components of deep-sea ferromanganese crusts using cation-exchange chromatography. The samples are digested in concentrated mineral acids, evaporated to near dryness, and redissolved in 0.5 N HCI. Solutions are passed through Bio-Rad AG50W-X8 strong cation-exchange resin in the H+ form. Major (Fe and Mn) and minor constituents (Al, Co, Cu, Ni, Ca, and Mg) are eluted with 1.7 or 2.0 N HCl; the REE are then eluted from the resin with 4.0 or 6.0 N HCl. Only Ba is not separated and coelutes from the resin with the REE. The method quantitatively separates the lanthanides from most matrix constituents and greatly facilitates their rapid sequential analysis by ICP/AES. The method has been shown to yield accurate and precise analyses of ferromanganese minerals for their REE content in the U.S. Geological Survey standard Fe-Mn nodule A-l and has been applied to Fe-Mn crusts from our collection.