Publishing type：Research paper (scientific journal)   Publisher：IWA Publishing  

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Many rural residents in developing countries drink water contaminated with feces due to inadequate purification, causing many diarrheal deaths, most of them infants. We have fabricated a protonated (H+-retaining) mordenite-embedded non-woven fabric sheet (H-MES) as a new tool for disinfecting drinking water at home. Proton retention amount was 1.2 mmol per gram of mordenite, 75% of its cation-exchange capacity. The H-MES released protons through cation exchange with cations in aqueous solutions, lowering the pH of the solutions to below 4. This low pH led to disinfecting 100 mL of 100-fold diluted TSB solutions containing an Escherichia coli species (DH5α). For example, an initial viable count of around 5,000 CFU mL−1 decreased to 14 CFU mL−1 after 24 h shaking at 25 °C with added H-MES containing 0.2 g protonated mordenite; 3.8×107 CFU mL−1 without the H-MES. Adding a nitric acid solution showed a similar effect, but using chemical reagents at home might lead to unexpected accidents. Adding and removing the H-MES to and from household waterpots by hand is easy. Besides the H-MES, similar sheets embedded with bactericides and bacterial adsorbents could be a simple water-disinfection tool for rural residents.

DOI： 10.2166/washdev.2022.202

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Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Pyrite is one of the most common Fe-S minerals found in submarine hydrothermal environments. Previous studies demonstrated that the Fe-S mineral can be a suitable host for Fe(II)-oxidizing microbes in hydrothermal environments; however, the details of microbial Fe(II) oxidation processes with Fe-S mineral alteration are not well known.

DOI： 10.1128/aem.00977-21

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Conventional washing methods release little radioactive cesium fixed in soils. Adding a Cs+ adsorbent to a suspension of Cs-contaminated soil rapidly removes the Cs+ released to the solution, causing more Cs+ release from the soil. We investigated this method by adding a sheet embedded with mordenite powder to a suspension of 133Cs+-retaining wet/dry montmorillonite and water/0.1 mol L−1 KNO3. Adding the sheet increased Cs+ release in all cases, with the highest increase for wet montmorillonite in water. The advantages of this method are the easy removal of the sheet from the suspension and the low Cs concentration in the final solution.

DOI： 10.1007/s10967-021-07878-7

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© 2020, The Author(s). The upper oceanic crust is mainly composed of basaltic lava that constitutes one of the largest habitable zones on Earth. However, the nature of deep microbial life in oceanic crust remains poorly understood, especially where old cold basaltic rock interacts with seawater beneath sediment. Here we show that microbial cells are densely concentrated in Fe-rich smectite on fracture surfaces and veins in 33.5- and 104-million-year-old (Ma) subseafloor basaltic rock. The Fe-rich smectite is locally enriched in organic carbon. Nanoscale solid characterizations reveal the organic carbon to be microbial cells within the Fe-rich smectite, with cell densities locally exceeding 1010 cells/cm3. Dominance of heterotrophic bacteria indicated by analyses of DNA sequences and lipids supports the importance of organic matter as carbon and energy sources in subseafloor basalt. Given the prominence of basaltic lava on Earth and Mars, microbial life could be habitable where subsurface basaltic rocks interact with liquid water.

DOI： 10.1038/s42003-020-0860-1

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© 2020 In this study, we developed a novel non-destructive method, a combined μXRF–μXAFS live soil imaging chamber method, to directly observe the local behavior of metal(loid)s in the oxidative–reductive layer typically found in waterlogged soil such as flooded paddy soil. The newly-designed soil chamber was made of titanium plate and glass with low gas permeability and high corrosion resistance, and thus specializes in the experiment of the waterlogged soil with anoxic environment. The soil chamber can be mounted directly in the synchrotron μXRF–μXAFS beamline. Hence, by using this method, we can observe the intact paddy soil without physical and chemical disturbances. The application of μXRF-μXAFS analysis allows us to analyze the elemental abundances and chemical speciation of soil elements at a microscale. In addition, since the μXRF–μXAFS has both and high elemental selectivity and high applicability for various elements, we can investigate the behavior of target element as well as its relationships with related elements. In this study, we applied the new method to examine the behavior of arsenic (As) in the oxidative–reductive layer formed at the surface of flooded paddy soil. The μXRF imaging of As-contaminated paddy soil newly showed that As in the soil was strongly accumulated in the topsoil layer in a millimeter scale by 1 month incubation under flooded condition. Moreover, the μXAFS analysis of As and related metals indicated that the As accumulation was closely attributed to the change in the oxidation state of As with soil depth and the coexistence of the most favored sorbent (Fe(III) hydroxides) in the oxidative–reductive layer of the paddy soil.

DOI： 10.1016/j.geoderma.2020.114415

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© 2020 Elsevier Ltd In this study, we investigated the microscale behavior of arsenic (As) in an oxic-anoxic interface in laboratory-incubated paddy soil by combining multiple techniques, micro X-ray fluorescence spectrometry combined with micro X-ray absorption fine structure (μXRF-μXAFS), microelectrodes, and quantitative polymerase chain reaction (qPCR) analyses. A steep redox gradient with depth was observed in the topsoil millimeter layer (depth: 0–4.6 mm) after 15 days, oxidative condition in the surface soil and reductive condition in deeper soil, due to the limited oxygen supply caused by flooding. Microscale elemental mapping of the top soil layer by μXRF showed that a large amount of the As (about 10% of total) in the system strongly accumulated within the top 3 mm soil layer after 15 days of incubation. Direct As speciation by extended X-ray absorption fine structure (EXAFS) indicated that the host phases of As in the accumulation layer were the Fe(III) hydroxides included in the soil, which were the dominant Fe species in the layer. Direct As speciation by micro X-ray absorption near edge structure (μXANES) showed that the dominant As species in the As accumulation and depletion zones were clearly changed. Specifically, the oxidized species As(V) increased in the As accumulation (top surface) layer, and the reduced species As(III) decreased in the As depletion (deeper) layer. Direct Fe speciation also showed that the most abundant fraction of Fe in the accumulation layer was the Fe(III) hydroxides such as ferrihydrite, the most preferable sorbent for As. These findings suggest that the As accumulations observed in the study are significantly associated with As reduction and oxidation in the oxic-anoxic interface of paddy soil. Specifically, more labile As(III) formed in the reductive deeper layer migrates to the upper layer, the migrated As(III) is oxidized to As(V) in oxidative surface millimeter layer, and the As(V) is then scavenged by Fe(III) hydroxides that have high affinity for As(V); this is a possible mechanism for the strong accumulation of As observed in the topsoil layer in this study. In addition, manganese (Mn) and iron (Fe) μXANES analyses and microbial As(III) oxidase gene (aioA) quantification by qPCR suggested that As(III) oxidation in the top layer, which acted as a trigger reaction for As accumulation, might be induced by both chemical and microbial oxidation processes. The findings in this study indicate that the paddy soil system could potentially have a strong ability to prevent As migration to the floodwater. Our findings also indicate that the millimeter-scale topsoil layer in the flooded paddy soil could biogeochemically influence the whole As behavior in the paddy fields. Thus, to fully understand and predict As fate and migration in the paddy fields, we should investigate localized physical, chemical, and, biological properties of paddy soil.

DOI： 10.1016/j.gca.2020.01.038

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© 2019, The Author(s). Ferromanganese minerals are widely distributed in subseafloor sediments and on the seafloor in oceanic abyssal plains. Assessing their input, formation and preservation is important for understanding the global marine manganese cycle and associated trace elements. However, the extent of ferromanganese minerals buried in subseafloor sediments remains unclear. Here we show that abundant (10 8 –10 9 particles cm −3 ) micrometer-scale ferromanganese mineral particles (Mn-microparticles) are found in the oxic pelagic clays of the South Pacific Gyre (SPG) from the seafloor to the ~100 million-year-old sediments above the basement. Three-dimensional micro-texture, and major and trace element compositional analyses revealed that these Mn-microparticles consist of poorly crystalline ferromanganese oxides precipitating from bottom water. Based on our findings, we extrapolate that 1.5–8.8 × 10 28 Mn-microparticles, accounting for 1.28–7.62 Tt of manganese, are globally present in oxic subseafloor sediments. This estimate is at least two orders of magnitude larger than the manganese budget for nodules and crusts on the seafloor. Subseafloor Mn-microparticles thus contribute significantly to the global manganese budget.

DOI： 10.1038/s41467-019-08347-2

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

© 2018 In the present study, we investigated secondary products formed on the surface of altered basaltic glass from the sediment-basalt interface by multiple characterizations with EPMA, μXANES, μEXAFS, TEM, and EELS. μXANES and EPMA analyses showed that secondary products with high Fe abundance were precipitated on the surface of basalt glass and that the Fe species in the secondary product was dominantly composed of Fe(III) oxides, hematite, which was also agreeable with EELS result. Characterization by TEM and μEXAFS suggested that the hematite was nanoparticulate with particle size of 10–20 nm. This is the first study showing the occurrence of nanosized hematite as secondary products in altered basaltic glass, although there are many studies on the formation of Fe(III) (hydr)oxides in basalt alteration.

DOI： 10.1016/j.chemgeo.2018.10.005

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Mariprofundus micogutta strain ET2 was isolated in 2014 from a deep-sea hydrothermal field on the Bayonnaise Knoll of the Izu-Ogasawara arc. Here, we report its draft genome, which comprises 2,497,805 bp and contains 2,417 predicted coding sequences.

DOI： 10.1128/genomeA.00342-18

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IWA Publishing  

Although many kinds of materials for water purification are known, easy-to-use methods that ensure the safety of drinking water for rural populations are not sufficiently available. Sorbent-embedded sheets provide methods for the easy removal of contaminants from drinking water in the home. As an example of such a sorbent-embedded sheet, we prepared a Linde type A (LTA) zeolite-embedded sheet (ZES) and examined its Pb(II) removal behaviour. Different amounts of LTA were added either as powder or as ZES to 0.3 mM Pb(NO3)2 solutions containing 2.5 mM Ca(NO3)2, in which the ratio of the negative charges in LTA to the positive charges in Pb(II) (LTA/Pb ratio) ranged from 1 to 20. After shaking, the mixtures were centrifuged to remove the powder, while the ZES was simply removed from the mixture by hand. The LTA powder removed more than 99% of the Pb(II) from the solution at all LTA/Pb ratios within 1 h, while the ZES removed &gt
99% of the Pb(II) at LTA/Pb ratios of 2 and higher
at the highest LTA/Pb ratio of 20, the ZES removed &gt
99% of the Pb(II) in 30 s. Therefore, the use of appropriate sorbent-embedded sheets enable the facile removal of contaminants from water.

DOI： 10.2166/wh.2017.160

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© 2018, Japanese Society of Microbial Ecology. All rights reserved. In the present study, the influence of the co-contamination with various chemical forms of antimony (Sb) with arsenite (As[III]) on soil microbial communities was investigated. The oxidation of As(III) to As(V) was monitored in soil columns amended with As(III) and three different chemical forms of Sb: antimony potassium tartrate (Sb[III]-tar), antimony(III) oxide (Sb2O3), and potassium antimonate (Sb[V]). Soil microbial communities were examined qualitatively and quantitatively using 16S rDNA-and arsenite oxidase gene (aioA)-targeted analyses. Microbial As(III) oxidation was detected in all soil columns and 90–100% of added As(III) (200 μ mol L–1) was oxidized to As(V) in 9 d, except in the Sb(III)-tar co-amendments that only oxidized 30%. 16S rDNA-and aioA-targeted analyses showed that the presence of different Sb chemical forms significantly affected the selection of distinct As(III)-oxidizing bacterial populations. Most of the 16S rRNA genes detected in soil columns belonged to Betaproteobacteria and Gammaproteobacteria, and some sequences were closely related to those of known As(III) oxidizers. Co-amendments with Sb(III)-tar and high concentrations of Sb2O3 significantly increased the ratios of aioA-possessing bacterial populations, indicating the enrichment of As(III) oxidizers resistant to As and Sb toxicity. Under Sb co-amendment conditions, there was no correlation between aioA gene abundance and the rates of As(III) oxidation. Collectively, these results demonstrated that the presence of different Sb chemical forms imposed a strong selective pressure on the soil bacterial community and, thus, the co-existing metalloid is an important factor affecting the redox transformation of arsenic in natural environments.

DOI： 10.1264/jsme2.ME17182

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

A novel iron-oxidizing chemolithoautotrophic bacterium, strain ET2(T), was isolated from a deep-sea sediment in a hydrothermal field of the Bayonnaise knoll of the Izu-Ogasawara arc. Cells were bean-shaped, curved short rods. Growth was observed at a temperature range of 15-30 A degrees C (optimum 25 A degrees C, doubling time 24 h) and a pH range of 5.8-7.0 (optimum pH 6.4) in the presence of NaCl at a range of 1.0-4.0 % (optimum 2.75 %). The isolate was a microaerophilic, strict chemolithoautotroph capable of growing using ferrous iron and molecular oxygen (O-2) as the sole electron donor and acceptor, respectively; carbon dioxide as the sole carbon source; and either ammonium or nitrate as the sole nitrogen source. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the new isolate was related to the only previously isolated Mariprofundus species, M. ferrooxydans. Although relatively high 16S rRNA gene similarity (95 %) was found between the new isolate and M. ferrooxydans, the isolate was distinct in terms of cellular fatty acid composition, genomic DNA G+C content and cell morphology. Furthermore, genomic comparison between ET2(T) and M. ferrooxydans PV-1 indicated that the genomic dissimilarity of these strains met the standard for species-level differentiation. On the basis of its physiological and molecular characteristics, strain ET2(T) (= KCTC 15556(T) = JCM 30585 (T)) represents a novel species of Mariprofundus, for which the name Mariprofundus micogutta is proposed. We also propose the subordinate taxa Mariprofundales ord. nov. and Zetaproteobacteria classis nov. in the phylum Proteobacteria.

DOI： 10.1007/s00203-016-1307-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

This study investigated how silver nanoparticles (AgNP) and ionic silver (AgNO3) undergo phase transformations in soils under aerobic and anaerobic conditions using extended X-ray absorption fine structure (EXAFS) spectroscopy. After 30 days of aerobic incubation, 88% of AgNP added to the soil remained persistent, whereas AgNO3 was completely transformed into Ag associated with humus and clay minerals. In the anaerobic soil, 83% of the spiked AgNP was transformed into Ag2S, accompanied by significant decrease in water- and acid-extractable Ag fractions. About 50% of AgNO3 spiked to the anaerobic soil underwent transformations into metallic Ag and associations with clay minerals. Oxide (Ag2O) and carbonate (Ag2CO3) forms of Ag were not predominant in aerobic and anaerobic soils. The redox potential of soil had a profound effect on determination of the phase-transformation pathways for AgNP and ionic Ag. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jhazmat.2015.09.001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

To clarify the partitioning and isotopic fractionation of boron (B) into the gas and particle phases in the atmosphere, the concentrations and isotopic compositions of gaseous and particulate B were measured concurrently for more than one year at a site in Shizuoka City, Japan. This area has few anthropogenic sources of B, such as coal combustion facilities. Gaseous B concentration showed clearly a seasonal variation, increasing during summer and decreasing during winter. Conversely, particulate B concentration tended to decrease during the warm season and increase during winter. The increase in gaseous B concentration during summer is attributable to the enhanced emissions of B from sea-salt degassing owing to higher temperatures and the predominance of winds from the Pacific Ocean. Moreover, the decrease in gaseous B concentration and the increase in particulate B concentration during winter is probably due to the enhanced condensation of gaseous B on atmospheric particles. The delta B-11 values of gaseous and particulate B varied largely, and did not indicate a distinctive seasonal variation. A positive correlation was observed between the delta B-11 values of gaseous and particulate B (R-2 = 0.518, P &lt; 0.001). Moreover, the delta B-11 values of particulate B were approximately 0-20%0 lower than those of gaseous B. There is an isotopic fractionation (Delta(B(OH4--B(OH)3)) of about -20%0 between B(OH)(3) and B(OH)(4)(-) species in solution (Kakihana et al., 1977). This tends to support the hypotheses that gaseous B is transformed to particulate B through the reaction of condensed B(OH)(3) with chemical constituents on particles to precipitate borates, and that the condensed B(OH)(3) remaining on particles is unstable and evaporates. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2016.11.013

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© 2017, Japanese Society of Microbial Ecology. All rights reserved. Natural bacteriogenic iron oxides (BIOS) were investigated using local-analyzable synchrotron-based scanning transmission X-ray microscopy (STXM) with a submicron-scale resolution. Cell, cell sheath interface (EPS), and sheath in the BIOS were clearly depicted using C-, N-, and O- near edge X-ray absorption fine structure (NEXAFS) obtained through STXM measurements. Fe-NEXAFS obtained from different regions of BIOS indicated that the most dominant iron mineral species was ferrihydrite. Fe(II)- and/or Fe(III)-acidic polysaccharides accompanied ferrihydrite near the cell and EPS regions. Our STXM/NEXAFS analysis showed that Fe species change continuously between the cell, EPS, and sheath under several 10-nm scales.

DOI： 10.1264/jsme2.ME17009

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC MICROBIOLOGY  

It has been suggested that iron is one of the most important energy sources for photosynthesis-independent microbial ecosystems in the ocean crust. Iron-metabolizing chemolithoautotrophs play a key role as primary producers, but little is known about their distribution and diversity and their ecological role as submarine iron-metabolizing chemolithotrophs, particularly the iron oxidizers. In this study, we investigated the microbial communities in several iron-dominated flocculent mats found in deep-sea hydrothermal fields in the Mariana Volcanic Arc and Trough and the Okinawa Trough by culture-independent molecular techniques and X-ray mineralogical analyses. The abundance and composition of the 16S rRNA gene phylotypes demonstrated the ubiquity of zetaproteobacterial phylotypes in iron-dominated mat communities affected by hydrothermal fluid input. Electron microscopy with energy-dispersive X-ray microanalysis and X-ray absorption fine structure (XAFS) analysis revealed the chemical and mineralogical signatures of biogenic Fe-(oxy) hydroxide species and the potential contribution of Zetaproteobacteria to the in situ generation. These results suggest that putative iron-oxidizing chemolithoautotrophs play a significant ecological role in producing iron-dominated flocculent mats and that they are important for iron and carbon cycles in deep-sea low-temperature hydrothermal environments.

DOI： 10.1128/AEM.01151-16

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Language：Japanese   Publisher：Japanese Society of Soil Science and Plant Nutrition  

DOI： 10.20710/dojo.87.5_394

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC MICROBIAL ECOLOGY, DEPT BIORESOURCE SCIENCE  

Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary. Large amounts of anaerobic groundwater and natural gas, mainly methane (CH4) and nitrogen gas (N-2), are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N-2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt. Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen (H-2)-producing fermentative bacteria and H-2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism. Our results also demonstrated that N-2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall.

DOI： 10.1264/jsme2.ME16091

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DOI： 10.20710/dojo.87.4_283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

During Integrated Ocean Drilling Program (IODP) Expedition 329, a deep-sea ferromanganese nodule and surrounding sediment were collected from the South Pacific Gyre, the most oligotrophic oceanic environment on earth. Using a combination of cryo-sectioning and fluorescence-based cell counting techniques, we determined that the microbial cell density at the very surface of the nodule was similar to 10(8) cells cm(-3), three orders of magnitude higher than that in the surrounding sediment. Analysis of bacterial and archaeal 16S rRNA gene sequences (similar to 1400 bp) indicated that the taxonomic composition of the nodule-associated community differed markedly from that of the sediment-associated community. Members of Marine Group I (MGI) Thaumarchaeota are potentially crucial for sustaining the high cell density because both ammonia and Cu were available on the nodule surface, making it suitable for ammonia-oxidizing chemolithoautotrophy mediated by copper enzymes. Combined cryo-sectioning and synchrotron analysis of the nodule surface revealed both hexagonal birnessite resembling delta-MnO2 and triclinic birnessite, minerals characteristic of biogenic oxide and its secondary product, respectively. Regardless of these possible biogenic features, only one gene sequence exhibited some similarity to previously identified manganese-oxidizing bacteria. On the other hand, MGI Thaumarchaeota were assumed as potential candidate of manganese oxidizers because they have multi-copper oxidase that is utilized by most known manganese oxidizers. Therefore, this archaeal group is considered to play a significant ecological role as a primary producer in biogeochemical elemental cycles in the ultra-oligotrophic abyssal plain. (C) 2016 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2016.04.021

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© 2016, microbes and environments All right reserved. We herein investigated the mechanisms underlying the contact leaching process in pyrite bioleaching by Acidithiobacillus ferrooxidans using scanning transmission X-ray microscopy (STXM)-based C and Fe near edge X-ray absorption fine structure (NEXAFS) analyses. The C NEXAFS analysis directly showed that attached A. ferrooxidans produces polysaccharide-abundant extracellular polymeric substances (EPS) at the cell-pyrite interface. Furthermore, by combining the C and Fe NEXAFS results, we detected significant amounts of Fe(II), in addition to Fe(III), in the interfacial EPS at the cell-pyrite interface. A probable explanation for the Fe(II) in detected EPS is the leaching of Fe(II) from the pyrite. The detection of Fe(II) also indicates that Fe(III) resulting from pyrite oxidation may effectively function as an oxidizing agent for pyrite at the cell-pyrite interface. Thus, our results imply that a key role of Fe(III) in EPS, in addition to its previously described role in the electrostatic attachment of the cell to pyrite, is enhancing pyrite dissolution.

DOI： 10.1264/jsme2.ME15137

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DOI： 10.20665/kakyoshi.64.3_114

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

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DOI： 10.14862/geochemproc.63.0_89

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Language：Japanese   Publisher：一般社団法人 日本土壌肥料学会  

DOI： 10.20710/dohikouen.62.0_161_1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The depth of oxygen penetration into marine sediments differs considerably from one region to another1,2. In areas with high rates of microbial respiration, O-2 penetrates only millimetres to centimetres into the sediments(3), but active anaerobic microbial communities are present in sediments hundreds of metres or more below the sea floor(4-7). In areas with low sedimentary respiration, O-2 penetratesmuchdeeper(8-12) but the depth to which microbial communities persist was previously unknown(9,10,13). The sediments underlying the South Pacific Gyre exhibit extremely low areal rates of respiration(9). Here we show that, in this region, microbial cells and aerobic respiration persist through the entire sediment sequence to depths of at least 75 metres below sea floor. Based on the Redfield stoichiometry of dissolved O-2 and nitrate, we suggest that net aerobic respiration in these sediments is coupled to oxidation of marine organic matter. We identify a relationship of O-2 penetration depth to sedimentation rate and sediment thickness. Extrapolating this relationship, we suggest that oxygen and aerobic communities may occur throughout the entire sediment sequence in 15-44% of the Pacific and 9-37% of the global sea floor. Subduction of the sediment and basalt from these regions is a source of oxidized material to the mantle.

DOI： 10.1038/NGEO2387

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Relationships between the concentrations of 13 trace elements and delta N-15 were identified to investigate the trophic-level-dependent accumulation of elements in biota from Suruga Bay, Japan. The results showed biomagnification for Hg, As and Se (very weak for As and Se), biodilution for Cd, Cu, Mn, Ni, Pb, Sb and Zn, and nontrophic relationships for Co, Cs and Mo. It is likely that the biomagnification of Hg does not differ significantly with the location, whereas some trace elements, such as As, Se and Zn, show a characteristic trophic transfer in each location, depending on the food web structure and environmental factors.

DOI： 10.1007/s10872-014-0261-5

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DOI： 10.14862/geochemproc.62.0_199

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© 2015 The Chemical Society of Japan. In the present study, we applied a scanning transmission X-ray microscopy (STXM) technique to investigate the spatial distribution of biomolecules at the microbe-mineral boundary during bioleaching process of pyrite (FeS2). STXM-based carbon and oxygen near-edge X-ray absorption fine structure (NEXAFS) directly showed that polysaccharides were localized within 150 nm of the bacteria-pyrite boundary and that sessile bioleaching bacteria produced polysaccharides-abundant extracellular biomolecules on the pyrite grain. The STXM-based NEXAFS technique has multiple advantages: (i) a high spatial resolution less than 50 nm, (ii) a nondestructive analytical technique with a high element of specificity, (iii) X-ray spectroscopic chemical speciation useful for the analysis of hydrated biomolecules. Thus, the STXM-based NEXAFS technique is a powerful tool to investigate the mechanism of biological process occurring at the microbe-mineral interface.

DOI： 10.1246/cl.140880

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DOI： 10.14934/chikyukagaku.48.131

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_29

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEOCHEMICAL SOC JAPAN  

The atmospheric concentrations of nonsea-salt (nss) SO42- and trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, V, and Zn) were measured for aerosol samples collected concurrently at ten sites across Japan during winter (December to February in 2004-2006), when the contribution of Asian outflow to their concentrations would have been maximized. The sulfur isotope ratio (delta S-34) of nss SO42- was also measured and used to identify the sources of nss SO42- in the aerosols. Sites in urban and industrial areas tended to have high concentrations of nss SO42- and trace elements. In other sites, however, the concentrations of nss SO42- and trace elements decreased with increasing longitude. On the basis of the delta S-34 values of nss SO42- and the results of air trajectory analysis, it is likely that the regional variations in the concentrations of nss SO42- and trace elements are strongly related to their emissions in the regions over which the air mass passed, particularly in the 30-40 degrees N region, which has the highest emissions in China. To evaluate the relative contribution of Asian outflow to the concentrations of nss SO42- and trace elements at each site, for convenience we assumed that the fraction dominated by Asian outflow (referred to as the Asian outflow fraction) corresponds to the concentrations expected from an exponential concentration-longitude relationship among three sites that are far from major emission areas in Japan. For nss SO42- and As, much higher contributions of the Asian outflow fraction (93% and 83% on average, respectively, at 10 sites) were observed, whereas for the other trace elements, only average contributions were observed at all the sites, i.e., within 50-67%. The high contributions of Asian outflow to the concentrations of nss SO42- and As are attributable to a marked difference in their emissions from coal combustion between China and Japan.

DOI： 10.2343/geochemj.2.0323

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In this study, we investigated the behavior of Sb(V) during the transformation of poorly crystalline Fe(III) oxyhydroxides (two-line ferrihydrite) with various Sb/Fe molar ratios at pH 6.0. Both XRD and Fe EXAFS analyses confirmed that goethite and hematite are the primary transformation products of the ferrihydrite in the presence of Sb(V). The crystallization kinetics showed that the transformation rate with Sb(V) was approximately the same as that of the control (without Sb(V)), which indicates that the presence of Sb(V) does not influence the transformation rate to a noticeable extent. Throughout the transformation, Sb(V) dominantly partitioned in the solid phase and no desorption of Sb(V) was observed. Furthermore, Sb EXAFS analyses suggested that Sb(V) in the solid phase is structurally incorporated into crystalline goethite and/or hematite generated by the ferrihydrite transformation. Hence, Sb(V) transfers into the thermodynamically stable solids from the metastable ferrihydrite with aging, indicating a rigid immobilization of Sb(V). These findings are valuable for making predictions on the long-term fate of Sb associated with ferrihydrite in natural environments. © 2013 American Chemical Society.

DOI： 10.1021/es4010398

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

In the present study, we investigated As behavior in a high-As hot spring (Sambe hot spring, Shimane, Japan) by coupling direct chemical speciation by synchrotron-based XAFS and HPLC-ICP-MS with microbial As-redox transformation gene analysis. The concentration of soluble As in the spring streamwater decreased immediately along the flow in correlation with Fe behavior, indicating that As in the streamwater was naturally attenuated in the streamwater. Iron XAFS analysis suggested deposition of Fe(III) oxyhydroxides along the flow. Thus, considering the strong affinity of As to Fe oxyhydroxides, the observed attenuation in As was possibly caused by sorption (or incorporation) of As on Fe(III) oxyhydroxides. Both dissolved As(III) and As(V) were present in the aqueous phase, and As(III) was rapidly oxidized to As(V) (&lt;30 s) along the flow. The oxidation kinetics indicated the occurrence of biotic As(III) oxidation, because obtained As(III) oxidation rate (6.7-7.8 mu M min (1)) was much faster than the reported abiotic oxidation rates. Furthermore, the bacterial arsenite oxidase gene (aioA) was detected in DNA extracted from all samples (average of 2.0 x 10(5) copies dry g (1)), which also supported potential attributes of biological As(III) oxidation in situ. In solid phase samples from sampling points analyzed by XAFS, most of the As existed as oxidized pentavalent form, As(V). This result indicated that this form was preferentially partitioned to the solid phase because of the much higher affinity of As(V) than of As(III) to Fe(III) oxyhydroxides. Considering the kinetic and microbiological findings, it is indicated that biotic process was predominantly responsible for As(III) oxidation at the present site, and this biotic As(III) oxidation to As(V) controlled the observed attenuation of As, because oxidized As(V) was removed from the aqueous phase by Fe(III) oxyhydroxides more efficiently. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apgeochem.2013.04.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The atmospheric concentrations and isotopic compositions of sulfur and boron were measured for aerosol samples (water soluble fraction) collected from April 2004 to March 2006 at two sites on the Japan Sea coast. SO42- originating from sea salts in the aerosols was negligible (only 1-2% of the total SO). The atmospheric concentrations of nonsea-salt SO (S-nss) and total B (B-T) were scattered widely, but the concentration ratio B-T/S-nss was relatively high during winter and relatively low during summer. Moreover, aerosols during winter were characterized by a high delta S-34 (delta S-34(nss)) of nonsea-salt SO42- and a low delta B-11 (delta B-11(T)) of total B, whereas aerosols during summer were characterized by a low delta S-34(nss) and a high delta B-11(T). A negative correlation (r(2) = 0.34, p &lt; 0.001) was observed between delta S-34(nss) and delta B-11(T) in aerosols from the two sites, suggesting that those values are governed primarily by a mixing of two end-members. On the basis of air trajectory analysis, the first end-member is the air mass from "Northern China (&gt;30 degrees N)", whereas the second end-member is the air mass from "Japan and the Pacific Ocean". It is likely that SO24- and B in the air mass from northern China are strongly affected by coal burning, which satisfactorily reflects the characteristics of delta S-34 and delta B-11 (i.e., high delta S-34 and low delta B-11) of coals formed in this region. Thus, both sulfur and boron isotopes in aerosols are effective as tracers of emissions from coal burning in northern China mainly during winter when the air mass from this region is dominant. On the other hand, the results of source identification suggested that the major sources of SO24- and B in the air mass from Japan and the Pacific Ocean are oil combustion in Japan and ocean sea salts, respectively. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.atmosenv.2012.11.025

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Integrated Ocean Drilling Program (IODP) Expedition 329 made major strides toward fulfilling its objectives. Shipboard studies documented (1) fundamental aspects of habitability and life in this very low activity subseafloor sedimentary ecosystem and (2) first-order patterns of habitability within the igneous basement. A broad range of postexpedition studies will complete the expedition objectives. Throughout the South Pacific Gyre (SPG
Sites U1365- U1370), dissolved oxygen and nitrate are present throughout the entire sediment sequence, and sedimentary microbial cell counts are lower than at all previously drilled IODP/ Ocean Drilling Program (ODP)/Deep Sea Drilling Program (DSDP) sites. In contrast, at Site U1371 in the upwelling zone just south of the gyre, detectable oxygen and nitrate are limited to the top and bottom of the sediment column, manganese reduction is a prominent electron-accepting process, and cell concentrations are higher than at the same depths in the SPG sites throughout the sediment column. Geographic variation in subseafloor profiles of dissolved and solid-phase chemicals are consistent with the magnitude of organic-fueled subseafloor respiration declining from outside the gyre to the gyre center. Chemical profiles in the sedimentary pore water and secondary mineral distributions in the basaltic basement indicate that basement alteration continues on the timescale of formation fluid replacement, even at the sites with the oldest basement (84-120 Ma at Sites U1365 and U1366).

DOI： 10.2204/iodp.sd.15.01.2013

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The contribution of abiogenic and biogenic particles to trace-metal (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Ti, V, and Zn) composition was investigated for phytoplankton (primarily diatoms) collected in Shimizu Port, a coastal seawater region. Except for Cd, the trace metals occurred predominantly in lithogenic or nonlithogenic abiogenic particles associated with plankton. In contrast, it is likely that Cd in seawater is taken up intracellularly, and not adsorbed extracellularly by phytoplankton. The lower P-normalized quotas of Cd in Shimizu Port than in offshore regions may be because plankton are dominated by diatoms.

DOI： 10.1007/s10872-012-0140-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We report the concurrent sorption of As(V) and Mn(II) during biogenic manganese oxide (BMO) formation by Acremonium strictum strain KR21-2. Mn(II) sorption experiments with preformed BMOs in N-2-purged HEPES buffer solutions showed that immature BMOs formed with shorter cultivation times have a higher Mn(II) sorption capacity. The sorption capacity for Mn(II) decreased as the BMOs matured. Average oxidation state analysis and two-step extraction revealed that the contents of sorbed Mn(II) and structural Mn(III) were higher in immature BMOs and decreased as the BMOs matured. A positive relationship between sorbed Mn(II) and structural Mn(III) throughout BMO formation suggested that the latter, which is predominant in immature BMO, acts as the sorption site for Mn(II). The sorption of co-existing As(V) was positively related to sorbed Mn(II), implying the concurrent sorption of As(V) and Mn(II). XANES analyses showed a cultivation-time dependent change in the shape of the post-edge spectrum of As(V), suggesting change in As(V) sorption mode during BMO formation. The concurrent sorption of As(V) and Mn(II) on immature BMO possesses higher capacity for As(V) sequestration (As(V)/Mn ratio up to 0.13), leading to its potential applicability for As(V) remediation. The results presented here provide new insights on As(V) cycles in the environment, as the reactivity of BMOs makes them one of the most important classes of compounds that affect the fate of a variety of elements. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.chemgeo.2012.03.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Ubiquitous presence of microbes in aquatic systems and their inherent ability of biomineralization make them extremely important agents in the geochemical cycling of inorganic elements. However, the detailed mechanisms of environmental biomineralization (e.g., the actual reaction rates, the temporal and spatial dynamics of these processes) are largely unknown, because there are few adequate analytical techniques to observe the biogenic oxidation/reduction reactions in situ. Here, we report a novel technical approach to characterize specific biominerals associated with a target microbe on high spatial resolution. The technique was developed by combining directly in situ phylogenetic analysis, fluorescence in situ hybridization (FISH), with a synchrotron microprobe method, micro X-ray absorption fine structure spectroscopy (mu-XAFS), and was applied to iron mineral deposition by iron(II)-oxidizing bacteria (IOB) in environmental samples. In situ visualization of microbes revealed that in natural iron mats, Betaproteobacteria dominated by JOB were dominantly localized within 10 mu m of the surface. Furthermore, in situ chemical speciation by the synchrotron microprobe suggested that the Fe local structure at the IOB accumulating parts was dominantly composed of short-ordered Fe-O-6 linkage, which is not observed in bulk iron mat samples. The present study indicates that coupled XAFS-FISH could be a potential technique to provide direct information on specific biogenic reaction mediated by target microorganism.

DOI： 10.1021/es203860m

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

In the present study, we investigated the behavior of arsenic (As) during the transformation of poorly crystalline iron(III) hydroxide, ferrihydrite. Adsorbed As on solids gradually decreased as ferrihydrite transformed to crystalline goethite and hematite. X-ray absorption fine structure (XAFS) analysis indicated that the As immobilization dominantly resulted from the incorporation of arsenate into poorly crystalline ferrihydrite under present experimental conditions.

DOI： 10.1246/cl.2012.270

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DOI： 10.1038/ngeo2387

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Speciation of iron (Fe) precipitated on bacterial stalks was studied by Fe K-edge mu-XRF-XAFS. Micro-XRF analysis of the stalk samples showed that Fe is precipitated around the stalk. All the mu-XANES spectra at several Fe-accumulated parts showed similar spectra. This study indicated that synchrotron mu-XRF-XAFS is a powerful tool for chemical speciation of metals at single-cell level for bacteria bearing metal.

DOI： 10.1246/cl.2011.680

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MINERALOGICAL SOC AMER  

In soil near tailings from an antimony (Sb) mine, we found micro-grains coated with an antimony-rich layer. These grains were characterized in detail using multiple advanced analytical techniques such as micro-X-ray absorption near edge structure (mu-XANES), micro-extended X-ray absorption fine structure (mu-EXAFS), micro-X-ray diffraction (mu-XRD), transmission electron microscope (TEM), and electron probe microanalysis (EPMA). The EPMA showed that one soil grain (grain A) locally accumulated a large amount of Sb in the secondary phases (40-61 wt% Sb2O5) with significant Fe (20-28 wt% Fe2O3). The spatial distribution of Sb in the grain was similar to that of iron. Both Fe mu-XANES and mu-XRD of the Sb hot spots in grain A consistently showed that the secondary products were dominantly composed of ferric antimonate, tripuhyite (FeSbO4). Fits to the Sb K-edge mu-EXAFS of this phase showed second-neighbor coordination numbers similar to 30% smaller than in bulk tripuhyite, indicating that the tripuhyite included in grain A is nanoparticulate and/or has a high structural disorder. The TEM analysis suggests that the particle size of tripuhyite in grain A was around 10 nm, which is consistent with the size range indicated by mu-XRD and mu-EXAFS. This is the first report showing tripuhyite with nanocrystallinity in natural soil to date.

DOI： 10.2138/am.2011.3651

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：COPERNICUS GESELLSCHAFT MBH  

In the North Pacific, transport and deposition of mineral dust from Asia appear to be one of major sources of iron which can regulate growth of phytoplankton in the ocean. In this process, it is essential to identify chemical species of iron contained in Asian dust, because bioavailability of iron in the ocean is strongly influenced by the solubility of iron, which in turn is dependent on iron species in the dust. Here, we report that clay minerals (illite and chlorite) in the dusts near the source collected at Aksu (western China) can be transformed into ferrihydrite by atmospheric chemical processes during their long-range transport to eastern China (Qingdao) and Japan (Tsukuba) based on the speciation by X-ray absorption fine structure (XAFS) and other methods such as X-ray diffraction and chemical extraction. As a result, Fe molar ratio in Aksu (illite : chlorite : ferrihydrite = 70 : 25 : 5) was changed to that in Tsukuba (illite : chlorite : ferrihydrite = 65 : 10 : 25). Moreover, leaching experiments were conducted to study the change of iron solubility. It was found that the iron solubility for the dust in Tsukuba (soluble iron fraction: 11.8% and 1.10% for synthetic rain water and seawater, respectively) was larger than that in Aksu (4.1% and 0.28%, respectively), showing that iron in the dust after the transport becomes more soluble possibly due to the formation of ferrihydrite in the atmosphere. Our findings suggested that secondary formation of ferrihydrite during the transport should be considered as one of important processes in evaluating the supply of soluble iron to seawater.

DOI： 10.5194/acp-11-11237-2011

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The loads and sources of heavy metals (Cd, Co, Cu, Mn, Mo, Ni, Pb, V, and Zn) in the midstream of Tama River were evaluated on the basis of their chemical analyses in ordinary and stormwater runoff from July 2007 to November 2008. Tama River is one of the three major rivers flowing into Tokyo Bay. The total annual water discharges differed largely for 2007 and 2008, depending on the scales of typhoon rainfalls and other heavy rainfalls in each year. The concentrations of the metals other than Mo in the river did not change markedly at a flow rate of less than approximately 200 m(3) s(-1), but at higher flow rates, the concentrations of all the metals increased linearly with the increase in the log of flow rate (r (2) = 0.94-0.99). The annual loads of heavy metals for 2007 and 2008 were estimated using regression equations between the above parameters and the hourly flow rate data for each year. For the metals other than Mo, the contribution of the loads at higher flow rates (&gt; 200 m(3) s(-1)) was much larger than that at lower flow rates (&lt; 200 m(3) s(-1)), showing the importance of the particulate loads (primarily crustal materials) during storm runoff following typhoon rainfalls and other heavy rainfalls. In contrast, the loads of Mo at lower flow rates accounted for major portions (56-78%) of the total loads, because of a relatively small contribution of particulate load during storm runoff. The contribution of the loads of Mo, Zn, Cd, Cu, and Ni at lower flow rates to the annual loads was larger than that of other metals. It was found that the concentrations of these metals in ordinary runoff are strongly affected by the discharge of treated water from sewage treatment plants which are located along the catchment. Thus, treated water from sewage treatment plants may be the primary source contributing to the present pollution of Mo, Zn, Cd, Cu, and Ni in Tokyo Bay.

DOI： 10.1007/s11270-010-0391-3

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Language：Japanese   Publisher：Japan Association of Mineralogical Sciences  

In this study, we investigated local structures of Sb species in synthetic Sb(V)-coprecipitated and -adsorbed ferrihydrite and goethite, which are common Fe(III) oxyhydroxides in environment, at various Sb/Fe molar ratios by extended X-ray absorption fine structure (EXAFS) analyses. In the EXAFS spectra of the coprecipitated ferrihydrite and goethite, some features of the spectra significantly differed from those in the adsorbed samples. The EXAFS simulation indicated that the difference is due to the larger coordination number of Fe to Sb atom in the coprecipitation samples, indicating a structural incorporation (heterovalent substitution) of Sb(V) into ferrihydrite and goethite. This study directly provided the first evidence for the structural incorporation of Sb(V) into the Fe(III) oxide structure.

DOI： 10.14824/jakoka.2010.0.41.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In this study, we investigated local structures of Sb species in synthetic Sb(V)-coprecipitated and -adsorbed ferrihydrite and goethite, which are common iron(III) oxyhydroxides in environment, at various Sb/Fe molar ratios by extended X-ray absorption fine structure (EXAFS) analyses. The EXAFS analyses showed that Sb(V) is adsorbed on ferrihydrite and goethite by the formation of an inner-sphere surface complex at pH 7.5. In the EXAFS spectra of the coprecipitated ferrihydrite and goethite, some features of the spectra significantly differed from those in the adsorbed samples. The EXAFS simulation indicated that the difference is due to the larger coordination number of the Fe atom to the Sb atom in the coprecipitation samples, indicating a structural incorporation (heterovalent substitution) of Sb(V) into ferrihydrite and goethite. The incorporation of Sb(V) into the structure was also confirmed in natural iron(III) oxyhydroxides in contaminated soil near an Sb mine tailing using mu-EXAFS. This study directly provided the first evidence for the structural incorporation of Sb(V) into the iron(III) oxide structure. Our findings are important for understanding the fate of Sb in the aquatic environment because the behavior of the elements incorporated into solids by such a substitution is not greatly influenced by aquatic factors such as the pH and ionic strength because of isolation of the incorporated metal(loid) ions from the aqueous phase.

DOI： 10.1021/es903901e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The aim of this study was to determine the mechanism of Sb immobilization occurring under reductive soil conditions. In this work, we investigated the distribution and speciation of Sb in reductive soil formed in Sb mine tailing by micro-X-ray absorption near edge structure spectroscopy (mu-XANES) and electron probe microanalyzer (EPMA). EPMA and Fe K-edge mu-XANES analyses of the soil grains indicated that Sb in soil was strongly associated with Fe(III) hydroxides secondarily formed during sedimentation. The Sb concentrations in Sb hot-spot were found to be as high as 10-30 wt % (as Sb(2)O(5)). We also found quartz particles coated by secondary rims bearing Fe(III) hydroxides and Sb. The Sb K-edge mu-XANES analyses of the rims showed that a significant amount of Sb(III) was present only at the surfaces of the rims (thickness &lt; 10 mu m), indicating that Sb reduction occurred in the reducing soil. The facts suggest that the reduction to Sb(III) in the system can be an important factor for Sb immobilization under reducing conditions, since the Sb(III) sorbs more strongly on Fe(III) hydroxides than Sb(V) and its solubility is also much lower than that of Sb(V) species.

DOI： 10.1021/es902942z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The aim of this study was to determine the mechanism of Sb immobilization occurring under reductive soil conditions. In this work, we investigated the distribution and speciation of Sb in reductive soil formed in Sb mine tailing by micro-X-ray absorption near edge structure spectroscopy (mu-XANES) and electron probe microanalyzer (EPMA). EPMA and Fe K-edge mu-XANES analyses of the soil grains indicated that Sb in soil was strongly associated with Fe(III) hydroxides secondarily formed during sedimentation. The Sb concentrations in Sb hot-spot were found to be as high as 10-30 wt % (as Sb(2)O(5)). We also found quartz particles coated by secondary rims bearing Fe(III) hydroxides and Sb. The Sb K-edge mu-XANES analyses of the rims showed that a significant amount of Sb(III) was present only at the surfaces of the rims (thickness &lt; 10 mu m), indicating that Sb reduction occurred in the reducing soil. The facts suggest that the reduction to Sb(III) in the system can be an important factor for Sb immobilization under reducing conditions, since the Sb(III) sorbs more strongly on Fe(III) hydroxides than Sb(V) and its solubility is also much lower than that of Sb(V) species.

DOI： 10.1021/es902942z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

It was found that the amount of arsenite incorporated into calcite is Much less than that of arsenate. The result suggests that the sequestration of arsenic by coprecipitation with calcite cannot be an important chemical process under reducing conditions, Such as in groundwater where arsenite is the dominant arsenic species.

DOI： 10.1246/cl.2009.910

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Green rusts (GRs), which are mixed ferrous/ferric hydroxides, occur in many suboxic soils and sediments and are thought to play an important role in the fate and transport of many inorganic contaminants. In this study, the interaction of Sb with sulfate GR (GRSO(4)) was investigated using multitechnique approaches such as X-ray absorption fine structure (XAFS), XRD, and BET analyses. XANES analyses show that the oxidation states of Sb(V) sorbed on GRSO(4) is dominantly Sb(V), suggesting that GRSO(4) does not work as a strong reductant in the system of the present study. The sorption experiment, EXAFS, and XRD results suggested that there are two bonding modes for Sb(V) sorption on GRSO(4), (i) the sorption to edge sites with inner-sphere complex and (ii) to interlayer surface with outer-sphere complex. In addition, it was found that fraction (i) is dominant for Sb(V) sorption on GRSO(4). The transformation of "metastable" GRSO(4) was inhibited by the presence of Sb(V). The transformed products of GRSO(4), such as magnetite and Fe(OH)(2), have larger surface areas and higher capacities as adsorbent for Sb(V) than GRSO(4), and the fraction of the transformed product largely affects the distribution of Sb between water and solid, a mixture of GRSO(4), magnetite, and Fe(OH)(2).

DOI： 10.1021/es8026067

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Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.56.0.105.0

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DOI： 10.14862/geochemproc.56.0.104.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The oxidation state and coordination environment of antimony (Sb) incorporated into polyethylene terephthalate (PET) bottles were estimated based on X-ray absorption fine structure (XAFS) at Sb K-edge. Prior to XAFS analyses, Sb concentrations in 177 PET bottles collected in Japan and China were determined, showing that 30.5% and 100% of Japanese and Chinese PET bottles, respectively, contained more than 10 mg/kg of Sb. Most of the bottles used for aseptic cold filling and carbonated drinks contained a larger amount of Sb. Extended X-ray absorption fine structure (EXAFS) showed that the first neighboring atom of Sb in PET was estimated to be oxygen with a coordination number of about three. In addition, the contribution of Sb to Sb shell was discounted in the EXAFS, showing that Sb was not present as Sb(2)O(3) in PET, although Sb was initially added as Sb(2)O(3) in the production of PET. This information is consistent with the coordination environment estimated from the polycondensation reaction catalyzed by Sb, where Sb can be present as either Sb glycolate or Sb glycolate binding to the end group of the PET polymer. X-ray absorption near-edge structure (XANES) showed that Sb(I 11) initially added as Sb(2)O(3) into PET was partially oxidized and the Sb(V) fractions reached approximately 50% in some samples. However, the oxidation state and coordination environment of Sb in PET had no relationship with the concentrations of Sb that leached into water from PET. Based on the present XAFS results and previous studies on the effects of temperature and others, it Was concluded that the leaching behavior of Sb into water is primarily due to the degradation of PET itself, but is not related to the Sb species in the PET bottles.

DOI： 10.1021/es802073x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Characterization of Fe(III) (hydr)oxides in soils near the Ichinokawa mine was conducted using X-ray absorption fine structure (XAFS) and Mossbauer spectroscopies, and the structural changes were correlated with the release of As into pore-water. The Eh values decreased monotonically with depth. Iron is mainly present as poorly-ordered Fe(III) (hydr)oxides, such as ferrihydrite, over a wide redox range (from Eh = 360 to -140 mV). Structural details of the short-range order of these Fe(III) (hydr)oxides were examined using Mossbauer spectroscopy by comparing the soil phases with synthesized ferrihydrite samples having varying crystallinities. The crystallinity of the soil Fe (hydr)oxides decreased slightly with depth and Eh. Thus, within the redox range of this soil profile, ferrihydrite dominated, even under very reducing conditions, but the crystalline domain size, and, potentially, particle size, changed with the variation in Eh. In the soil-water system examined here, where As concentration and the As(III)/As(V) ratio in soil water increased with depth, ferrihydrite persisted and maintained or even enhanced its capacity for As retention with increased reducing conditions. Therefore, it is concluded that As release from these soils largely depends on the transformation of As(V) to As(III) rather than reductive dissolution of Fe(Ill) (hydr)oxide. (C) 2008 Published by Elsevier Ltd.

DOI： 10.1016/j.apgeochem.2008.07.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Oxidation states of Sb and As in marine ferromanganese oxides determined by X-ray absorption near-edge structure showed that both As and Sb are pentavalent in the ferromanganese oxides. The concentration ratios of As/Sb in the ferromanganese oxides are similar to those in seawater. There results are consistent with the fact that As and Sb behave similarly, especially under oxic conditions as suggested from other studies in soil-water and river-sediment systems.

DOI： 10.1246/cl.2008.756

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Green rust (Fe-4(II)Fe-2(III)(OH)(12)SO4 center dot 3H(2)O) is an intermediate phase in the formation of iron (oxyhydr)oxides such as goethite, lep-idocrocite, and magnetite. It is widely considered that green rust occurs in many soil and sediment systems. Green rust has been shown to reduce sorbed Se(VI), Cr(VI), and U(VI). In addition, it is also reported that green rust does not reduce As(V) to As(III). In this study, we have investigated for the first time the interaction between Sb(V) and green rust using XAFS and HPLC-ICP-MS. Most of the added Sb(V) was adsorbed on green rust, and Sb(III), a reduced form, was observed in both solid and liquid phases. Thus, it was shown that green rust has high affinity for Sb(V), and that Sb(V) was reduced to more toxic Sb(III) by green rust despite the high stability of the Sb(V) species even under reducing condition as reported in previous studies. Therefore, green rust can be one of the most important reducing agents for Sb(V), which can influence the Sb mobility in suboxic environments where green rust is formed. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.chemosphere.2007.07.021

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DOI： 10.14862/geochemproc.55.0.347.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The oxidation states and host phases of Sb and As in soil samples of mine tailing (Ichinokawa mine, Ehime, Japan) and in laboratory soil-water systems were determined by X-ray absorption fine structure (XAFS) spectroscopy. HPLC-ICPMS was used for speciation of Sb and As in soil water. In the Ichinokawa soil water system, Sb was present exclusively as the oxidized form, Sb(V), over a wide redox range (from Eh = 360 to - 140 mV, pH 8), while As was present as a mixture of As(III) and As(V). This finding was confirmed in the laboratory experiments. These results suggest that Sb(V) is a very stable form in the environment and that Sb is oxidized at more negative Eh than As. Combining the results of Fe and Mn XAFS analyses and a positive correlation among Sb, As, and Fe abundances in the soil, the host phases of Sb and As in soil were Fe( III) hydroxide. XAFS analyses of Sb and As are also consistent with this finding. Under reducing conditions, the concentration of As in the soil water increased whereas that of Sb decreased in both the Ichinokawa and laboratory systems. This suggests that this contrasting behavior is controlled mainly by the different redox properties of Sb and As.

DOI： 10.1021/es060694x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A simple method for the observation of the kinetics of the reactions at the solid-water interface was developed using quick X-ray absorption fine structure combined with a column reactor. We applied the method to the oxidation reaction of As(III) by manganese oxide, a strong oxidizer in natural systems. A reliable reaction rate constant k', 3.9 x 10(-4) %(-1) min(-1) at pH 7.1, was obtained, where the effect of photooxidation under X-ray beam can be eliminated. Considering the average Mn/As molar ratio in the system, the value is reasonable compared with other reported values. Since this method is very simple, we can apply it to various elements and reaction systems at the solid-water interface as a tool to understand the kinetics of various reactions in detail.

DOI： 10.1021/ac060961h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Phthalate esters have become widespread contaminants in the aquatic environment, because of their extensive use as non-reactive plasticizers. There is, however, little accurate data on their solubility, transportation, and distribution in the aquatic environment. In this work, we have investigated the influence of humic acid on the water solubility of di-(2-ethylhexyl)phthalate (DEHP), one of the most frequently used phthalate esters in the laboratory studies for DEHP. We have also studied the solid-water distribution of DEHP in the presence of humic acid and particulate matter (activated carbon, ferrihydrite, and kaolinite) to simulate their distribution in a natural aquifer (ternary system). The results show that the water solubility of DEHP can be significantly increased by humic acid. The shape K (eq) value, the binding constant of DEHP between water and humic acid at equilibrium, was obtained by fitting experimental data for each humic acid. The shape K (eq) values in the ternary system apparently decreased in the order of ferrihydrite &gt; kaolinite approximate to octanol/water partition activated carbon systems. This result shows that the increase in the hydrophobicity of HA remaining in the solution will lead to the apparent increase of shape K (eq) in the system since more hydrophilic solid sorbs relatively more hydrophilic HA molecule. The solid-water partition coefficient (shape K (W-P) ) for DEHP in the environment estimated from this study is consistent with those reported based on the experiments for natural samples. Quantitative values obtained in this study, such as K'(ow), shape K (eq), and shape K (W-P) , can be useful for estimating the behavior of DEHP.

DOI： 10.1007/s11270-006-9115-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Determination of the oxidation state of Sb by X-ray absorption near-edge structure spectroscopy was conducted to soil samples in natural mine tailing and laboratory experiments. It was found that Sb was in oxidized form, Sb(V), rather than Sb(III) in soil under reductive condition in laboratory experiments (Eh = -222mV, pH 5.2) and in natural mine tailing samples (Eh = - 17 mV, pH 7.7). These results suggested that Sb exists dominantly as Sb(V) in soil under wide range of natural redox conditions.

DOI： 10.1246/cl.2005.1656

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Coupled application of multitracer method for the sorption experiments and ICP-MS for leaching experiments was proposed as a new method to study the dynamics of various elements in soil-water systems. This method enables us to obtain reversibility and the time required to attain the steady-state simultaneously for various elements in soil-water system. An example of the results obtained by this method was shown for the case of Co in this letter.

DOI： 10.1246/cl.2005.980

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

The details of a method used to determine the As(III)/As(V) ratio in soil by arsenic K-edge XANES spectroscopy are described. The spectra of mixtures of NaAs(III)O-2 and NaH(2)AS(V)O-4, conducted for an As(III)/As(V) calibration, were well-fitted by combining normalized spectra of NaAsO2 and Na2HAsO4, where the coefficients multiplied by the normalized spectra were identical to the molar ratio of As(III) and As(V) in the mixtures. XANES spectra of arsenic in soil samples could also be fitted by a linear combination of the spectra of NaAsO2 and Na2HAsO4, which enabled us to estimate the As(III)/As(V) in a soil containing 10.2 mg/kg arsenic. The As(III)/As(V) ratio in the soil was compared with that of a soil solution contacted with the soil determined by HPLC-ICP-MS, showing that As(III) is distributed to water more readily than As(V). The application of the XANES method is important for a better understanding of the behavior of As(III) and As(V) independently in a natural aquifer.

DOI： 10.2116/analsci.19.891

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Language：Japanese   Publisher：一般社団法人日本土壌肥料学会  

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世界各地の海洋環境において、酸化鉄で覆われた海底面（酸化鉄被膜地帯）が確認されている。それらは、環境中の鉄を直接的あるいは間接的に利用する微生物により形成された微生物と鉱物（主に酸化鉄）の複合体であり、それらの複合体（酸化鉄被膜）は、鉄利用微生物の生理・生態を理解する上で最適な試料であると考えられている。&lt;br&gt;&lt;br&gt; 我々はこれまでに、沖縄トラフやマリアナ島弧そして南部マリアナトラフの熱水活動域に存在する酸化鉄被膜地帯での微生物学的調査を行ってきた。本発表では、微生物群集構造解析から予想される酸化鉄被膜での生態系維持に最も貢献する一次生産者について議論し、培養手法によって明らかとなった新規鉄酸化細菌の存在とそれらの生化学的性状、酸化鉄被膜形成に関わる海洋性鉄利用微生物の生態について報告する。

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Language：Japanese   Publisher：一般社団法人日本土壌肥料学会  

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

DOI： 10.14862/geochemproc.61.0_40

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Language：Japanese   Publisher：GEOCHEMICAL SOCIETY OF JAPAN  

走査型透過X線顕微鏡（Scanning Transmission X-ray Microscopy: STXM）は、主に軟X線領域（おおよそ4 keV以下）において、フレネルゾーンプレートで集光した30 nm程度のサイズのX線を用い、透過配置で試料を走査あるいはエネルギーをスキャンして、元素あるいは化学種の分布や吸収スペクトルを測定する手法で、環境科学、微生物学、地球惑星科学、高分子化学、磁性材料などへの広い応用範囲を有する。我々のグループでは、独自の設計により市販品よりも大幅に小型で運搬が可能な装置（compact-STXM）を開発し、主に高エネルギー加速器研究機構Photon Factory (PF)のBL-13Aでの運用を開始し、その性能テストを行うと共に、様々な応用研究、特に環境化学・サステナブル科学に関する研究への応用を進めている。講演では、この装置の概要と利用研究について紹介する。

DOI： 10.14862/geochemproc.61.0_28

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DOI： 10.14862/geochemproc.60.0.28.0

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本研究において演者らは、アンチモンおよびヒ素の表層環境での挙動について主に化学種決定に着目することで研究を進めた。X線分析法の1つであるXAFS法を駆使して、元素の価数やホスト相を直接的に決定し、環境中でのアンチモンやヒ素の溶解、沈殿、拡散反応を支配する要因を解明した。

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