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U accumulations in 
naturally growing at the mill tailings pond; Iron plaque formation possibly related to root-endophytic bacteria producing siderophoresNakamoto, Yukihiro*; Doyama, Kohei*; Haruma, Toshikatsu*; Lu, X.*; Tanaka, Kazuya; Kozai, Naofumi; Fukuyama, Kenjin; Fukushima, Shigeru; Ohara, Yoshiyuki; Yamaji, Keiko*
Minerals (Internet), 11(12), p.1337_1 - 1337_17, 2021/12
Times Cited Count：1 Percentile：10.87(Geochemistry & Geophysics)Mine drainage is a vital water problem in the mining industry worldwide because of the heavy metal elements and low pH. Rhizofiltration using wetland plants is an appropriate method to remove heavy metals from the water via accumulation in the rhizosphere. is one of the candidate plants for this method because of metal accumulation, forming iron plaque around the roots. At the study site, which was the mill tailings pond in the Ningyo-toge uranium mine, 
has been naturally growing since 1998. The results showed that accumulated Fe, Mn, and U in the nodal roots without/with iron plaque compared with other plant tissues. Among the 837 bacterial colonies isolated from nodal roots, 88.6% showed siderophore production activities. Considering iron plaque formation around roots, we hypothesized that microbial siderophores might influence iron plaque formation because bacterial siderophores have catechol-like functional groups. The complex of catechol or other phenolics with Fe was precipitated due to the networks between Fe and phenolic derivatives. The experiment using bacterial products of root endophytes, such as 
spp. and 
spp., showed precipitation with Fe ions, and we confirmed that several 
spp. and 
spp. produced unidentified phenolic compounds. In conclusion, root-endophytic bacteria such as spp. and spp., isolated from metal-accumulating roots of , might influence iron plaque formation as the metal accumulation site. Iron plaque formation is related to tolerance in , and spp. and spp. might indirectly contribute to tolerance.
Fukuyama, Kenjin; Ohara, Yoshiyuki
no journal, ,
no abstracts in English
Kawamoto, Keisuke*; Ochiai, Asumi*; Takeda, Ayaka*; Nakano, Yuriko*; Yokoo, Hiroki*; Onuki, Toshihiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Utsunomiya, Satoshi*
no journal, ,
no abstracts in English
Takeda, Ayaka*; Nakano, Yuriko*; Ochiai, Asumi*; Yokoo, Hiroki*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Nagayasu, Takaaki; Onuki, Toshihiko*; Utsunomiya, Satoshi*
no journal, ,
no abstracts in English
Yamaji, Keiko*; Nakamoto, Yukihiro*; Haruma, Toshikatsu*; Doyama, Kohei*; Ohara, Yoshiyuki; Tanaka, Kazuya; Fukuyama, Kenjin; Fukushima, Shigeru
no journal, ,
no abstracts in English
Miyata, Naoyuki*; Okano, Kunihiro*; Fujibayashi, Megumi*; Ohara, Yoshiyuki; Nagayasu, Takaaki; Fukuyama, Kenjin
no journal, ,
no abstracts in English
U) and heavy metal (Fe, Mn) accumulation mechanism in phragmites australis influenced by root endophytic bacteriaNakamoto, Yukihiro*; Yamaji, Keiko*; Haruma, Toshikatsu*; Doyama, Kohei*; Ohara, Yoshiyuki; Tanaka, Kazuya; Fukuyama, Kenjin; Fukushima, Shigeru
no journal, ,
no abstracts in English
Yamaji, Keiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Nagayasu, Takaaki; Haruma, Toshikatsu; Tanaka, Kazuya; Masuya, Hayato*; Habe, Hiroshi*
no journal, ,
no abstracts in English
Kawamoto, Keisuke*; Ochiai, Asumi*; Takeda, Ayaka*; Nakano, Yuriko*; Yokoo, Hiroki*; Oki, Takumi*; Onuki, Toshihiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Utsunomiya, Satoshi*
no journal, ,
In the Ningyo-toge uranium mine, Okayama, Japan, various toxic elements such as U, As, and Ra are present in the mine wastewaters, of which the concentration except for Ra in the wastewater decrease below the regulatory limit by transport to the slag dumping pond. The mechanisms of decreasing their concentrations in the wastewaters are not fully understood. In order to understand the fundamental processes of natural attenuation at this site, we have investigated the wastewaters and solids from upstream to the pond at the downstream. Wastewater was contacted with oxygenated water and the amount of dissolved oxygen increased. Simultaneously dissolved ferrous iron was oxidized to form ferrihydrite nanoparticles, which are associated with silica colloids, As and U. The ferrihydrite nanoparticles as suspended colloids were transported to the pond in downstream, where the waste stream is completely oxidized. In the slag dumping pond, Mn dioxide, birnessite, dominantly occurs forming a mixture with ferrihydrite + silica colloid, which has a potential to adsorb Ra
. Consequently, Fe hydroxides nanoparticles and Mn dioxides in Ningyo-toge play a key role on removing U, As and Ra from the wastewater.
Habe, Hiroshi*; Inaba, Tomohiro*; Aoyagi, Tomo*; Aizawa, Hidenobu*; Sato, Yuya*; Hori, Tomoyuki*; Yamaji, Keiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Cai, H.*; et al.
no journal, ,
no abstracts in English
Yokoo, Hiroki*; Kawamoto, Keisuke*; Oki, Takumi*; Uehara, Motoki*; Onuki, Toshihiko*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Hochella, M. F. Jr.*
no journal, ,
no abstracts in English
Jiang, X.*; Tamura, Kenji*; Asano, Maki*; Haruma, Toshikatsu; Takahashi, Junko*; Fukuyama, Kenjin; Yamaji, Keiko*
no journal, ,
no abstracts in English
Jiang, Q.*; Tamura, Kenji*; Asano, Maki*; Fukuyama, Kenjin; Takahashi, Junko*; Yamaji, Keiko*
no journal, ,
In the former open-pit mining area of Ningyo-toge mine, 
is the dominant in its vegetation and the vegetation succession has been suspended for 2 decades. The present work was conducted to understand the soil micromorphological characteristics on this unusual area. We set two sampling sites (site A and site B) at the former open-pit mining area. Site A is in dominant vegetation, and site B is in 
dominant vegetation. Soil samples were taken from each horizon of the soil profiles for chemical analysis at the sites, and thin sections were obtained from the soil core samples (0-5 cm, 10-15 cm, 30-35 cm depth of site A and Site B, respectively). The BC horizon of site B has a lower Eh, which may be due to the less voids in the underlying soil, which results in seasonal accumulation of water. And the soil thin section observation showed that the 0-5cm of soil is in good structure, but the lower layer is not fully developed and forms a block structure. The content of the five forms of Fe and Mn are residual form 
oxide-bound form organic-bound form carbonate-bound form exchangeable form in this study site.
influenced by root endophytic bacteriaNakamoto, Yukihiro*; Yamaji, Keiko*; Haruma, Toshikatsu; Doyama, Kohei*; Ohara, Yoshiyuki; Fukuyama, Kenjin; Fukushima, Shigeru
no journal, ,
no abstracts in English
Haruma, Toshikatsu*; Doyama, Kohei*; Tanaka, Kazuya; Takahashi, Yoshio*; Fukuyama, Kenjin; Ohara, Yoshiyuki; Yamaji, Keiko*
no journal, ,
no abstracts in English
growing at the ore-sedimentary site; Iron plaque formation possibly related to endophytic bacteriaNakamoto, Yukihiro*; Doyama, Kohei*; Haruma, Toshikatsu*; Lu, X.*; Tanaka, Kazuya; Kozai, Naofumi; Fukuyama, Kenjin; Fukushima, Shigeru; Ohara, Yoshiyuki; Yamaji, Keiko*
no journal, ,
no abstracts in English
Tanaka, Kazuya; Yamaji, Keiko*; Masuya, Hayato*; Tomita, Jumpei; Ozawa, Mayumi; Fukuyama, Kenjin*; Ohara, Yoshiyuki*; Kozai, Naofumi
no journal, ,
no abstracts in English
naturally growing at a sedimentation site in an uranium mine associated with endophytic bacteriaHaruma, Toshikatsu*; Yamaji, Keiko*; Nakamoto, Yukihiro*; Doyama, Kohei*; Takahashi, Yoshio*; Tanaka, Kazuya; Kozai, Naofumi; Fukuyama, Kenjin*
no journal, ,
no abstracts in English
Jiang, Q.*; Tamura, Kenji*; Asano, Maki*; Fukuyama, Kenjin*; Yamaji, Keiko*
no journal, ,
This study was conducted to understand the soil macro and micromorphological characteristics on the former open pit mining area of Ningyo-toge mine. The vegetation succession of the area has not progressed. Its dominant vegetation has been 
. The conclusions of this study are follows. The BC horizon of Site B has a lower Eh, which may be due to the less voids in the underlying soil, which results in seasonal accumulation of water. The contents of Mn, Cd, Pb, and Co were higher than the average contents in Japanese soil, but they did not reach the level of pollution. The content of acid-soluble Fe was very low in the soil, Fe mainly is the form of residual and a part of reducible form in the study site. But, the content of Mn in acid-soluble form is high, and Mn has a greater impact on vegetation. In this study site, external human factors have a large influence, mixed with a large amount of black residue and wood chips. And the 0-5cm of soil is in good structure, but the soil in the lower layer is not fully developed and it is a block structure.
(Cav.) Trin. ex Steud. without iron plaque formationOkuma, Miyu*; Yamaji, Keiko*; Nakamoto, Yukihiro*; Fukuyama, Kenjin*; Tsunashima, Yasumichi
no journal, ,
At our study site, mill tailing pond, which is used as a temporary storage site to treat mine water containing iron, manganese, etc., (Cav.) Trin. ex Steud. has been found to grow naturally there; therefore, this plant was considered to have some metal tolerance mechanisms. Actually, was previously reported to enhance heavy metal tolerance through the formation of iron plaques; however, few iron plaques were observed on roots of growing Fe deposition site close to the entrance of mine water at our study site, suggesting that they may have another heavy metal tolerance mechanisms. The objective of this study was to elucidate the heavy metal tolerance mechanisms of , without iron plaque formation. Elemental analysis clarified that high concentrations of Fe, Al, and Zn were accumulated in healthy nodal roots; especially, excessive Fe accumulation was confirmed compared with normal plants. Detoxicant analysis in the roots indicated that phenolics and organic acids were not produced well to contribute to the tolerance. Due to the observation of sections of nodal roots stained with potassium ferrocyanide solution, Fe localization was observed in the epidermis and the cell walls of the outermost layers of the cortex cells. Since immobilization of heavy metals in the cell walls is known as one of the heavy metal tolerance mechanisms in plants, our results suggest that would show the tolerance to immobilize Fe in the cell walls to prevent from migrating into the interior cells.
Tanaka, Kazuya; Kurihara, Yuichi*; Tomita, Jumpei; Maamoun, I.; Yamasaki, Shinya*; Tokunaga, Kohei; Fukuyama, Kenjin*; Kozai, Naofumi
no journal, ,
We collected surface sediment and water samples at a U mill tailings pond in the Ningyo-toge center. Radioactivity concentrations of 
Ra in sediments were 12,000 - 29,000 Bq/kg while those in water ranged from 60 to 580 mBq/L. As a result, apparent distribution coefficients of Ra between ferric sediment and water were estimated to be 3.1 
10
- 3.8 10
mL/g, which were higher than reported ones for ferrihydrite and goethite. This suggests that another host on which Ra is strongly fixed would be present in sediment if we assume equilibrium between sediment and water. It is possible that Mn(IV) oxide as a minor component contributed to an increase in the apparent distribution coefficients. Another possibility is upward flow of pore water containing Ra or diffusion of Ra released from lower sediment layers. Either scenario provides additional input of Ra to surface sediment. In this case, surface sediment and water did not reach equilibrium with each other, but Ra concentrations in surface sediments were governed by dynamics through input of Ra from porewater as well as groundwater in sediment-water interaction.
