Tsutomu Sato | Hokkaido University (original) (raw)

Papers by Tsutomu Sato

Abstracts of annual meeting of The Clay Science Society of Japan, 2008

Journal of Nuclear Science and Technology, 2020

Titanate adsorbents have been used to remove Sr radioisotopes from contaminated water at the Fuku... more Titanate adsorbents have been used to remove Sr radioisotopes from contaminated water at the Fukushima Daiichi Nuclear Power Station site. This process leads to the generation of spent adsorbents, which require stabilization for long term storage and disposal. Geopolymers are candidates for matrices to achieve this consolidation. However, more data are needed to assess the leaching behavior of Sr from the adsorbents embedded in a geopolymer matrix. In this study, leaching experiments and observations of the Sr distribution of spent titanate adsorbent embedded in geopolymers, loaded with Sr at realistic concentrations were conducted. The experimental results illustrate that only 0.

Japan Geoscience Union, 2014

Geochemical data for ferruginous chemical sedimentary rocks (e.g., Banded Iron Formation: BIF) ha... more Geochemical data for ferruginous chemical sedimentary rocks (e.g., Banded Iron Formation: BIF) have been used to understand surface environments on early Earth. For example, enrichment of Cr relative to Ti in BIFs that occurred 2.48 billion years ago has been considered as a result of the chemical mobilization of Cr in acidic aqueous environments due to sulfide oxidation after the oxygenation of atmosphere [1]. While the Archean sedimentary environments studied in most previous works are limited to deeper settings, the 3.2 Ga Moodies BIF in the Barberton Greenstone Belt, South Africa also indicated that Cr was enriched in the BIF and was therefore chemically mobile in a shallow marine environments [2]. This finding could be significant because it may indicate the oxidation of, at least, some parts of the ocean and therefore, imply the emergence of oxygenic photosynthesis. However, spatial distribution of Cr enrichment in the BIF has not been well understood because the data were obt...

粘土科学討論会講演要旨集, Sep 7, 2010

Journal of Molecular Structure, 2010

Geochmica et Cosmochimica Acta

Water Air and Soil Pollution

Limnology, 2010

ABSTRACT We examined monthly changes in polycyclic aromatic hydrocarbons (PAHs) in sediment trap ... more ABSTRACT We examined monthly changes in polycyclic aromatic hydrocarbons (PAHs) in sediment trap samples collected from the northern basin of Lake Biwa, Japan, from September 2003 to July 2004 to elucidate the sources of PAHs in the lake. The most abundant concentrations were those of pyrene and fluoranthene, at μgg−1 levels throughout the sampling period, with a strong positive relationship (r=0.996, n=10, P&lt;0.01). From the monthly changes in each PAH concentration and their ratios, we suspected two different sources: petroleum sources of lighter PAHs and combustion sources of middle to heavier PAHs. Because pyrene and fluoranthene decreased significantly with time during the sampling period (P&lt;0.05) and an abnormally high ratio of phenanthrene to anthracene was reported in September 2003, it appears that petroleum was accidentally spilled in September 2003. Although perylene was commonly found at μgg−1 levels in the sediment, its concentration was comparable with those of the other PAHs in sediment trap samples. As perylene showed no significant relationship with other PAHs or other indicator molecules, we suspect that the source of perylene was different from those of other PAHs, and the perylene was mainly formed from its precursors after deposition. KeywordsPolycyclic aromatic hydrocarbons (PAHs)-Lake Biwa-Sediment trap

Water, Air, & Soil Pollution, 2013

ABSTRACT The release of anionic nuclides such as 129I from underground nuclear waste disposals is... more ABSTRACT The release of anionic nuclides such as 129I from underground nuclear waste disposals is of great environmental concern due to its long half-life and high mobility in alkaline environments. The leachability of iodide is largely dependent on the sorption capacity of various Ca-bearing minerals such as ettringite, hydrocalumite, and calcium silicate hydrate (C-S-H) which are common hydration products of cement materials. Moreover, the pore water chemistry of cement materials is dominated by Si, Al, and Ca during the initial stage of weathering, and the ratios of the ions present vary much depending on the source materials. Examining the mineral phases generated in Si–Al–Ca systems with respect to different ratios of Si, Al, and Ca and their interaction with iodide is important to better understand the sorption behavior of iodide in nuclear waste disposal facilities. In this study, the mineral synthesis in Si–Al–Ca systems was conducted under alkaline conditions at ambient temperature, and the sorption behavior of iodide with the mineral phases was investigated during and after the mineral formation. The results showed that portlandite, C-S-H, stratlingite (CASH), hydrocalumite, gibbsite, and amorphous compounds were precipitated from the systems, depending on the Si, Al, and Ca ratios. The K d values of iodide were greatly affected by the Ca content and relatively high Ca-containing phases such as hydrocalumite, C-S-H, CASH, and portlandite showed high iodide retention capacity. Hence, ensuring the formation of these secondary minerals by modification of the chemical composition of cement materials could assist in safety design of nuclear waste disposals.

Science of The Total Environment, 2005

Consumption of vegetables and fish contaminated with the heavy metals Cu, Zn, Pb, Cd, Hg, and Cr ... more Consumption of vegetables and fish contaminated with the heavy metals Cu, Zn, Pb, Cd, Hg, and Cr is the most likely route for human exposure in Tianjin, China. Health risks associated with these heavy metals were assessed based on the target hazard quotients (THQs), which can be derived from concentrations of heavy metals in vegetables and fish consumed in four districts (Dong Li, Xi Qing, Jin Nan, and Bei Chen) and the urban area of Tianjin, China. Individual metal THQ (&amp;amp;amp;amp;amp;amp;amp;lt;1) values indicate the relative absence of health risks associated with intake of a single heavy metal through consumption of either contaminated vegetables or fish only. However, consumption of both vegetables and fish would lead to potential health risks especially for children, since individual THQs for vegetables and fish would sum up to almost 1. If individual THQs resulting from crops consumption are considered, the health risks would be greater for children since the THQ values will always be &amp;amp;amp;amp;amp;amp;amp;gt;1. Risk contribution from Cr is minimal compared to the other elements. Hg is the major risk contributor for children in Bei Chen since the THQ contribution amounts to about 45% of the total THQ values due to vegetables and fish consumption. The health risk to adults in Ding Li is ascribed mainly to the intake of Cd by vegetables and fish consumption, which contributes a substantial fraction to the total THQ (about 51%).

Minerals Engineering, 2010

The release of toxic anions during the chemical weathering of alkaline wastes such as blast furna... more The release of toxic anions during the chemical weathering of alkaline wastes such as blast furnace slag and coal fly ash presents a serious problem to public health and the environment. This study investigated arsenate sorption behavior onto Mg-bearing minerals formed in the Mg-Si-Al system at alkaline pH conditions in order to understand the safe removal and encapsulation of arsenate by Mg-bearing minerals under such conditions. Sorption experiments were performed during and after mineral formation and leaching tests using phosphate bearing solution were conducted to understand arsenic association with the minerals. The results revealed that brucite (Mg(OH) 2), hydrotalcite (Mg 6 Al 2 (CO 3)(OH) 16 Á4(H 2 O)) and serpentine (MgSi 2 O 5 (OH) 4) have high uptake capacity for arsenate. However, arsenic incorporation was only observed during the formation of high Al content hydrotalcite and serpentine minerals and was greatly enhanced at higher temperature. This implies that by controlling pore water chemistry of alkaline wastes with high reactivity, the irreversible fixation of arsenic by Mg-bearing minerals in alkaline conditions can be expected.

Journal of Aerosol Science, 2005

The concentrations of trace metals in aerosols of different sizes in the suburban area of Kanazaw... more The concentrations of trace metals in aerosols of different sizes in the suburban area of Kanazawa, Japan were determined with inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that, among the anthropogenic elements, the ambient concentration of Zn in the total suspended particles (TSP) was the highest (1386 ng/m 3) and Cd concentration was the lowest (0.45 ng/m 3). For the contribution of each particle size fraction to the total metal concentration in aerosols, except for V (33.6%), the "very coarse" aerosol size range (> 11 m) contributed a small mass fraction (only 4.05-11.7%). While the "coarse fraction" (11-3.3 m) had the largest mass percentage for most elements. However, the mass percentage of individual metals to the total sum of all investigated metals in each particle size range (from very coarse to very fine) was quite similar, which implied that the coagulation of airborne particles occurred in the study area due to the high humidity over the sampling period. High enrichment factor (EF) values (18.87-1139) were obtained for Zn, Cd, Pb and Cu reflecting the importance of anthropogenic inputs. In contrast, the EF values calculated for V, Ca, Mg, Mn, Sr and Co were low (1.05-15.81) suggesting that they were primarily of natural sources. The concentration ratios of natural sources derived elements (V, Ca, Mg, Mn and Sr) to Fe, and anthropogenic elements (Cd, Pb and Cu) to Zn are quite close in each particle size range, revealing that Fe can be a fine indicator for the prediction of ambient concentrations along with their size distributions of other elements mainly from natural processes, and Zn can be a favorable surrogate for assessment of air pollution resulting from volatile trace elements in this area.

Environmental Science & Technology, 2006

Sorption isotherms of pyrene on original and heat-treated wood chars were examined to understand ... more Sorption isotherms of pyrene on original and heat-treated wood chars were examined to understand its sorption behavior. Pyrene in single-solute systems had nonlinear isotherms. Polanyi-based dual-domain model fit sorption data well, and the model results showed that the adsorption component dominated pyrene sorption by original char at all aqueous concentrations. In contrast, this adsorption component contributed a much lower fraction to the total sorption by the heat-treated char, and dominated only at low solute concentrations; with increasing concentration, partitioning became a predominant contributor to the total sorption. Competitive effect of four cosolutes, phenanthrene (Phen), benzo[a]anthracene (BaA), 2,2methylene-bis (4-methyl-6-tert-butylphenol) (MMBP), and phenol on pyrene sorption by original and treated chars was examined to understand the underlying mechanism of competition. Hydrophobicity (adsorbability) and molecular size of competitors played an important role in competition with pyrene by both chars, suggesting the direct competition for sorption sites and pore blockage mechanism. Competitive sorption results indicated that the fate and transport of hydrophobic organic chemicals (e.g., pyrene) could be strongly affected in the presence of coexisting organic contaminants with high hydrophobicity and large molecular size, thereby, enhancing the mobility and leachability of these chemicals.

Chemosphere, 2006

Aerosol samples were collected from Kanazawa, Japan to examine the size distribution of 12 elemen... more Aerosol samples were collected from Kanazawa, Japan to examine the size distribution of 12 elements and to identify the major sources of anthropogenic elements. Key emission sources were identified and, concentrations contributed from individual sources were estimated as well. Concentrations of elements V, Ca, Cd, Fe, Ba, Mg, Mn, Pb, Sr, Zn, Co and Cu in aerosols were determined with ICP-MS. The results showed that Ca, Mg, Sr, Mn, Co and Fe were mainly associated with coarse particles (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;2.1 microm), primarily from natural sources. In contrast, the elements Zn, Ba, Cd, V, Pb and Cu dominated in fine aerosol particles (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;2.1 microm), implying that the anthropogenic origin is the dominant source. Results of the factor analysis on elements with high EF(Crust) values (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10) showed that emissions from waste combustion in incinerators, oil combustion (involving waste oil burning and oil combustion in both incinerators and electricity generation plants), as well as coal combustion in electricity generation plants were major contributors of anthropogenic metals in the ambient atmosphere in Kanazawa. Quantitatively estimated sum of mean concentrations of anthropogenic elements from the key sources were in good agreement with the observed values. Results of this study elucidate the need for making pollution control strategy in this area.

Applied Clay Science, 2014

ABSTRACT Na-montmorillonite (Na+Mt) dissolution in a 0.3 mol dm− 3 NaOH solution has been investi... more ABSTRACT Na-montmorillonite (Na+Mt) dissolution in a 0.3 mol dm− 3 NaOH solution has been investigated at a pH of 12 at 70 °C using a combination of flow-through and batch-type experiments to constrain a predictive geochemical model. The flow-through dissolution experiments were conducted in a dispersed system (initial water/solid ratio = 1000 cm3 g− 1) with varying concentrations of Si and Al to derive a Na+Mt dissolution rate as a non-linear function of the Gibbs free energy of reaction, ΔGr,mont. This rate equation was used to simulate the batch-type Na+Mt reaction experiments conducted in a coagulated system (initial water/solid ratio = 20 cm3 g− 1) in order to examine the applicability of the ΔGr,mont rate equation to higher ΔGr,mont conditions and to understand the effect of secondary mineral precipitation on the dissolution rate. The model simulation of the batch-type experiment adopting the empirical rate equations of Na+Mt dissolution and secondary mineral analcime precipitation was able to reproduce the measured changes in the amount of dissolved Na+Mt and concentrations of Si and Al in solution. The results showed that the empirical rate equation of Na+Mt dissolution determined in the far from equilibrium dispersed system was applicable to the coagulated system over a higher ΔGr,mont range and that the concentrations of Si and Al in the batch experiment were controlled by the precipitation of analcime. This implies that the precipitation of secondary minerals will strongly influence the rate of Na+Mt dissolution in the coagulated system. The effects of secondary mineral precipitation on the montmorillonite (Mt) dissolution rate will be, therefore, important in the high density, low water/solid system such as the intended bentonite buffer to be used as the primary barrier in a purpose built repository for the geological disposal of nuclear waste.

粘土科学討論会講演要旨集, Sep 7, 2006

American Mineralogist, 2004

The sorption mechanism of arsenate [As(V)] on schwertmannite was investigated by means of batch s... more The sorption mechanism of arsenate [As(V)] on schwertmannite was investigated by means of batch sorption experiments as a function of As(V) concentration in acidic solution at 25 °C. Structural simulation indicated that the surface sites of schwertmannite comprised various O atom (or hydroxyl) and SO 4 groups. Sorption experiments showed that the reactive sites for As(V) sorption are surfacecoordinated SO 4 groups rather than surface hydroxyl groups, as reported in earlier studies. The As(V) sorption mechanism involves ligand exchange with surface-adsorbed and structural SO 4. The results of the sorption experiments also suggested monodentate As(V) coordination at the surface-adsorbed SO 4 sites [(Fe 1) 2 SO 4 ] and bidentate As(V) coordination at the structural SO 4 sites [(Fe 3) 2 SO 4 ]. The overall ligand-exchange reaction was 0.61 (Fe 1) 2 SO 4 + 0.39 (Fe 3) 2 SO 4 + 1.61 H 2 AsO 4-→ 1.22 Fe 1 H 2 AsO 4 + 0.39 (Fe 3) 2 HAsO 4 + 0.39 H + + SO 4 2where the 1 and 3 in Fe 1 and Fe 3 are coordination numbers. The equilibrium constant derived for the exchange reaction, log K EX = 4.96, describes the observed As(V) sorption behavior. Nanocrystalline materials like schwertmannite are widespread in nature and typically contain signiÞ cant amounts of anionic impurities, such as sulfate and silicate. Our results indicate that the effects of impurities can be signiÞ cant and should be considered in order to gain a realistic understanding of sorption processes in natural systems.