Published Papers - Yasumoto Jun

Biogenic Polyamines Capture CO2 and Accelerate Extracellular Bacterial CaCO3 Formation

Ko Yasumoto, Mina Yasumoto-Hirose, Jun Yasumoto, Ryo Murata, Shun-ichi Sato, Megumi Baba, Kanami Mori-Yasumoto, Mitsuru Jimbo, Yasukatsu Oshima, Takenori Kusumi, Shugo Watabe

Marine Biotechnology   16 ( 4 ) 465 - 474   2014 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Study on Influence of Design and Operation Factors on Effluent ATU-BOD and N-BOD Concentrations from Sedimentation Tank in Rural Sewerage Facilities

中野拓治, 安元純

農業農村工学会論文集 ( 公益社団法人 農業農村工学会 )  81 ( 283 ) 9 - 16   2013.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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The design and operation factors on the effluent ATU-BOD and N-BOD concentrations in sedimentation tank were investigated by using observed data in the rural sewerage facilities with biofilm process and activated-sludge process. The operational problems with occurrence of N-BOD were also studied on the basis of the results of BOD removal performance obtained from research data of the rural sewerage facilities with both processes. Regarding to effluent BOD concentrations in sedimentation tank with both processes, it was found that the biological nitrification reaction and nitrogenous compound had the considerable influence on the effluent N-BOD concentration in sedimentation tank. The effluent ATU-BOD concentration in sedimentation tank was assumed to be governed by first-order function with complete-mix system of biological treatment process in the rural sewerage facilities with both processes. It was recognized that the effluent ATU-BOD concentration in sedimentation tank with both processes were influenced by the design and operation factors such as influent ATU-BOD concentration, microorganisms (mixed liquor suspended solids/specific surface area of contact filter for fixed bed submerged filter), and average DO in reactor (contact aeration tank/aeration tank). The effluent ATU-BOD concentration in sedimentation tank with both processes were found to be predicted by the empirical formula of hydraulic retention time and the design/operation factors mentioned above. Consequently, it is important that the control in occurrence of N-BOD and operational countermeasure for decrease of ATU-BOD are effective to maintain BOD removal efficiency in the rural sewerage facilities with both processes.

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多変量解析を用いた石灰岩帯水層における地下水水質の統計的分類

安元純, 聖川健斗, 仲栄真史哉, 砥綿泰弘, 中野拓治

土木学会論文集 B1(水工学)(Web) ( 土木学会 )  69 ( 4 ) I.595-I.600 (J-STAGE) - 600   2013 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Multivariate statistical techniques, principal component and cluster analysis were applied to the data on groundwater quality of Limestone aquifer in the southern region of Okinawa, Japan, to extract principal factors corresponding to the different sources of variation in the hydrochemistry, with the objective of defining the main controls on the hydrochemistry at the regional scale. As a result of principal component analysis, ground water quality in the region could be classified into four principal components, that is, the groundwater is affected according to salt water and fertilizer (component 1), limestone dissolution (component 2), a redox state of a ground-water (component 3) and nitrogen accumulation/ denitrification (component 4). The cluster analysis was classified into four clusters according to the pollution situation of groundwater pollution in the study area, and the classification result was affected by season.

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地下水中硝酸性窒素濃度の時空間分布と形成要因について:― 沖縄県本島南部琉球石灰岩分布地域を例として ―

中野 拓治, 安元 純, 寺澤 春菜, 名和 規夫

農業農村工学会論文集 ( 公益社団法人 農業農村工学会 )  81 ( 4 ) 283 - 291   2013 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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琉球石灰岩分布地帯である沖縄本島南部地域地下水の硝酸性窒素について，現地観測データ等から時空間的動態を把握し，その形成要因を考察した．調査地域の硝酸性窒素は，正規確率分布によく適合しており，環境基準値（10mgL#U－1#UR）を若干超過するような濃度水準となっている．硝酸性窒素には，地下水流動に伴った上流から下流に向けた窒素負荷源が影響しているとともに，地下ダム築造で形成された地下水流動場に起因する流入・混合作用と希釈・脱窒作用が関与していることを確認できた．硝酸性窒素の経年変化には，農地からの窒素負荷による影響が示唆されるとともに，周年濃度変化には地下水位変動が影響していることを明らかにすることができた．

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連続流入間欠ばっ気活性汚泥方式の農業集落排水施設の窒素除去性能とその支配要因

中野拓治, 安元純

農業農村工学会論文集 ( 公益社団法人 農業農村工学会 )  80 ( 279 ) 253 - 260   2012.06 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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連続流入間欠ばっ気活性汚泥方式の農業集落排水施設の窒素除去性能とその支配因子について，供用中の施設から得られた観測データを用いて考察した．窒素除去性能には，硝化・脱窒工程でのばっ気槽内の酸化還元電位が大きく関与しており，安定した除去性能を確保するためには，撹拌工程においては撹拌時間，ばっ気撹拌工程ではばっ気時間・ばっ気強度の適切な設定を通じて，ばっ気撹拌終了時は酸化状態に，また，撹拌終了時には確実に還元状態となるような運転・管理条件を保つことが重要であることが確認された．また，ばっ気槽内がばっ気撹拌終了時に好気状態（ORP値で100mV程度），撹拌終了時に嫌気状態（ORP値で－50～－200mVの範囲）が確保されている条件では，窒素除去は完全混合流による1次反応に従っているとともに，窒素除去率は，ばっ気槽内のMLSS，水温，ばっ気撹拌終了時DO濃度，水理学的滞留時間を説明変数とする双曲線関数式から推定できることが示唆された．

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Submarine groundwater discharge and seawater circulation in a subterranean estuary beneath a tidal flat

Nakada Satoshi, Yasumoto Jun, Taniguchi Makoto, Ishitobi Tomonori

HYDROLOGICAL PROCESSES ( WILEY-BLACKWELL )  25 ( 17 ) 2755 - 2763   2011.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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A numerical simulation and stationary geophysical survey at Omaehama, Japan, described the hydrogeology in a tidal flat and adjacent sea water column. The simulation of a tidally influenced aquifer with inland fresh groundwater discharges showed three circulations in the subterranean tidal flat estuary: a small, tide-induced recirculation (TIR) near the sloping beach, a deeper circulation (DC) across the interface between saltwater and freshwater, and a large, tidal flat-induced circulation (TFIC) in the offshore subterranean tidal flat and slope. The horizontal distribution of the simulated submarine groundwater discharge (SGD) showed two peaks, depending on the distance from the coast along the transect line of tidal flat; the offshore peak was quantitatively consistent with the previously observed peak based on automated seepage measurements. Time-series of the observed resistivity profiles using a marine cable (140 m) showed the structure of the fresh water/salt water interface, and indicated a salt wedge intruding from the bottom aquifer and infiltration at the surface in the beach and nearshore tidal flat. The qualitative structure of the resistivity hardly changed at each tidal stage. These results qualitatively validated the circulation patterns shown by the numerical simulation. The source of this discharging groundwater in the tidal flat is a complex mixture of fresh groundwater derived from the landward aquifer, as well as locally recycled seawater, which can contribute to the purification of the nearshore seawater. Copyright (C) 2011 John Wiley & Sons, Ltd.

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有明海沿岸火山岩地域における海底湧水の湧出機構と栄養塩の輸送特性

安元純, 広城吉成, 末益大嗣, 高岡秀朋, 神野健二

水工学論文集(CD-ROM) ( 公益社団法人 土木学会 )  55 ( 4 ) ROMBUNNO.99 - I_594   2011.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Submarine Groundwater Discharge (SGD) is now recognized as a significant role to the ecology of coastal environment as well as river discharge. This paper takes a first step for highlighting nutrient transport through SGD to volcanic rock area along the Ariake Bay. SGD rates and their qualities along the coastal area of the Ariake Bay, Ohura, Saga Prefecture, Kawachi, Kumamoto Prefecture, and Fukae, Nagasaki Prefecture regions are investigated. As a result, SGD generally decreased with the distance from the shoreline except Ohura point where large seepage rate is observed. It is presumed that SGD could be classified into two types based on the rate of SGD and the geological structure. Then, it is indicated that the SGD oxidation-reduction condition varied with seepage rate and path way. The results of this study demonstrate that SGD may be considered as a significant source of nutrient to the coastal area in Ariake Bay.

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Degradation of subsurface environment due to human activities and climate variability in Asian cities

Makoto Taniguchi, Jun Shimada, Yoichi Fukuda, Makoto Yamano, Shin Ichi Onodera, Somkid Buapeng, Robert Delinom, Fernando Siringan, Chung Ho Wang, Backjin Lee, Jun Yasumoto, Keiko Yamamoto

IAHS-AISH Publication   ( 329 ) 124 - 129   2009 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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Degradation of subsurface environments has been studied in Tokyo, Osaka, Seoul, Bangkok, Manila, Taipei and Jakarta. The groundwater temperature observed in the study cities show the magnitude of timing of surface warming due to global warming and heat island effects. Recent new techniques using remote gravity measurement and isotope data enable us to evaluate the regional scale of groundwater issues. Groundwater contaminations and accumulated materials in the subsurface environment depend on the development stage of the cities. The material transports by groundwater have been evaluated. Stable isotopes data of the groundwater and soil water can tell us me origin of the contamination and processes. Copyright © 2009 IAHS Press.

有明海沿岸域の佐賀県太良町大浦沖における海底地下水湧出と栄養塩の輸送

安元純, 広城吉成, 高岡秀朋, 古市久士, 松原英隆, 神野健二

水工学論文集(CD-ROM) ( 公益社団法人 土木学会 )  51   ROMBUNNO.81 - 486   2007.02 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Submarine Groundwater Discharge (SGD) is now recognized as an important pathway between land and sea. This paper takes a first step for estimating nutrient inputs through SGD to Ariake Bay. SGD rates and its quality along the coast of the Ariake Bay off Oura region were investigated. As a result, it was shown that on-site SGD rate ranged from 0.01 to 20.52μm/s, and SGD flowed through shallow confined aquifers which consist of basalt and superposition pyroclastic fall with shorter residence time. Then, it was estimated that reduction reaction for SGD proceeded just up to denitrification, and SGD associated nutrient loads (N, P, SiO#D2#DR) are estimated at 1.40g/day, 0.07g/day, and 52.78g/day respectively. The results of this study demonstrate that SGD must be considered as a significant source of nutrient to the coastal sea area in Ariake Bay.

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Geochemical processes and their modeling at the fresh and salt water mixing zone

Kenji Jinno, Tosao Hosokawa, Yoshinari Hiroshiro, Keigo Akagi, Jun Yasumoto

Proceedings of the International Association of Hydrological Sciences, Red Books ( the International Association of Hydrological Sciences, IAHS )  320 ( 320 ) 191 - 196   2007 [ Peer Review Accepted ]

Type of publication: Research paper (international conference proceedings)

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Oxidation-reduction geochemical processes coupled with mass transport in a coastal aquifer is a unique subsurface environmental phenomenon to model. When a porous material is contaminated by organic carbons, nitrate is denitrified and manganese dioxide and oxi-iron hydroxide would be reduced. However, it is expected that the reduced divalent iron is oxidized once again by seawater when discharged to the sea. The paper discusses a numerical model of transport and geochemical reaction processes along the mixing zone of fresh and reduced salt water in a coastal aquifer. By comparing the numerical solution with experimental observations for the precipitation of divalent iron along the mixing zone, the validity of the model is demonstrated. Copyright © 2008 IAHS Press.

Relation between the depth of saltwater/freshwater interface estimated by Wenner method and the electric conductivity of groundwater

大年邦雄, 安元純, 藤原拓

地下水学会誌 ( 地下水学会誌 )  48 ( 3 ) 169 - 181   2006.08 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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It is known that electrical methods for s u rface geophysical survey might be capable to locate saline water in a coastal unconfined aquifer. This is the result of the increase in bulk conductivity with increasing in pore water conductivity. The relation between the depth of saltwater intrusion estimated by electrical method and the electric conductivity (EC) of pore water corresponding to its depth, however, is not verified quantitatively. This study revealed the quantitative relation that the estimated depth by Wenner method corresponds to EC of 3 mS/cm (Cl#U-#UR = 450 mg/l) of groundwater. Considering that such depth is the upper part of the mixing zone, electrical method will be the powerful measure for monitoring the saltwater intrusion in a wide farming area along the coast.

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感潮河川周辺域の不圧帯水層における塩水侵入の変動特性

安元純, 上荒磯聡, 六車麗子, 藤原拓, 大年邦雄

水工学論文集(CD-ROM) ( 公益社団法人 土木学会 )  50   ROMBUNNO.043 - 258   2006 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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Salt water intrusion in a coastal aquifer varies corresponding to the sea level and rainfalls. The influence of tidal river might be added to the behavior of salt water intrusion when the aquifer locates near the tidal river. Consequently it is easy to understand that the behavior of salt water bodies in such a situation will be quite complicated. The present study describes the findings about the salt water intrusion on the basis of the long-term field measurements conducted near a tidal river. Following findings were obtained: 1) The interface of fresh-salt water bodies in an aquifer consists of a wide mixing zone. 2) The depth of mixing zone varies cyclically and more largely during a spring tide than a neap tide. 3) Rainfalls may have the possibility to uplift the upper mixing zone remarkably for a short period after the rainfall event. Such possibility has to be verified in the future.

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海岸帯水層における塩水侵入深の時間変動特性に及ぼす感潮河川の影響

安元純, 芝洋輔, 藤原拓, 大年邦雄

地下水学会誌 ( 地下水学会誌 )  46 ( 4 ) 299 - 313   2004.11 [ Peer Review Accepted ]

Type of publication: Research paper (scientific journal)

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河川感潮域においては,潮汐に伴う海面および感潮河川の水位変動が海岸帯水層への塩水侵入の時空間変動特性に影響を及ぼしていると考えられる.しかし,これらの要因を定量的に分離するのは通常の調査では困難である.本研究では,河口水門を閉じて感潮河川の水位を一定時間固定し,そのことが地下水への塩水侵入に及ぼす影響を観測により検討した.河川水位の固定化に伴って地下水位および淡塩境界の変動が抑制されること,河川近傍ほど抑制程度の大きいことがわかった.また,淡塩境界面モデルを用いた数値計算により観測結果を検証するとともに,河川水位を固定する時間長と地下水への影響持続時間長との関係について検討した.

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