糠澤 桂 (ヌカザワ ケイ)

NUKAZAWA Kei

写真a

職名

助教

研究分野・キーワード

水文生態学

ホームページ

http://keinukazawa.webcrow.jp/home.html

出身大学 【 表示 / 非表示

  •  
    -
    2008年03月

    岩手大学   工学部   建設環境工学科   卒業

出身大学院 【 表示 / 非表示

  •  
    -
    2013年03月

    東北大学  工学研究科  土木工学専攻  博士課程  修了

取得学位 【 表示 / 非表示

  • 東北大学 -  博士(工学)

専門分野(科研費分類) 【 表示 / 非表示

  • 環境動態解析

  • 水工学

 

研究経歴 【 表示 / 非表示

  • 水文モデルを用いた河川環境評価

    共同研究  

    研究期間: 2010年04月  -  継続中

論文 【 表示 / 非表示

  • Preliminary assessment of the impacts of sediment sluicing events on stream insects in the Mimi River, Japan

    Nukazawa K., Kajiwara S., Saito T., Suzuki Y.

    Ecological Engineering   145   2020年02月  [査読有り]

    共著

     概要を見る

    Dam sedimentation is a crucial issue that interferes with flood control and electric power generation. To address this, sediment dredging, bypass tunnel, flushing, and sluicing have been applied. Despite the potential impacts of these operations on stream environments, few studies have explored the environmental/ecological consequences of such regime shifts in sediment dynamics. Specifically, impacts of sediment sluicing on stream fauna have never been reported. This study assessed primary impacts of sediment sluicing events operated with the two cascade dams (the Saigo and Ouchibaru Dams) on stream insects in the lower Mimi River, Japan. The sediment sluicing, accompanied by a major flooding event in the river, was first operated in September 2017. Stream insect data downstream of the four cascade dams, including the two sluicing dams and a reference river, were collected yearly or biyearly in winter and summer from 2010 to 2018. Following the initiation of retrofitting the Saigo Dam for optimizing sediment sluicing, a downstream reach of the dam experienced marked perturbations in terms of both individual density and species richness. The density and richness dramatically decreased and the community significantly differed in winter 2017 from pre-impact conditions. The density, richness, and community composition subsequently recovered in winter 2018, even after the sediment sluicing impact, suggesting that the anticipated negative ecological impacts of the sluicing are limited. Non-metric multidimensional scaling and permutational multivariate analysis of variance revealed distinct differences in communities between summer and winter samples at non-regulated sites or sites farther downstream of the dam that are characterized by fewer Simuliidae in summer and relatively abundant Heptageniidae. This could serve as a reference for assessments of ecological consequences of sediment sluicing in the region.

    DOI

  • Are bacteria potential sources of fish environmental DNA?

    Nukazawa K., Akahoshi K., Suzuki Y.

    PLoS ONE   15 ( 3 )   2020年  [査読有り]

    共著

     概要を見る

    The environmental DNA (eDNA) method is being increasingly applied in various environments. Although eDNA undergoes rapid degradation in aqueous environments, it has been detected in streams up to 10 km downstream from its source. As environmental bacteria can uptake free DNA, transfer their genetic traits, and amplify, there is a potential risk that they, rather than a target aquatic species, could become a source of measured eDNA. This study examined whether bacteria with incorporated fish DNA could be such a source by investigating the detectability of fish DNA generated by bacteria inhabiting river water and riverbed sediment. We attempted to detect common carp (Cyprinus carpio) eDNA in stream water and sediment samples and the DNA of common carp produced by bacterial colonies (Escherichia coli, total coliform, and heterotrophic bacteria) cultured from the samples. The eDNA was detected in the environmental samples but the carp DNA from the targeted bacteria was rarely detected in both water and riverbed sediment samples. Our results suggest that the risk of bacterium-induced false positive detection for fish eDNA is negligible.

    DOI

  • Fast, sensitive, and reliable detection of waterborne pathogens by digital PCR after coagulation and foam concentration

    Jikumaru A., Ishii S., Fukudome T., Kawahara Y., Iguchi A., Masago Y., Nukazawa K., Suzuki Y.

    Journal of Bioscience and Bioengineering     2020年  [査読有り]

    共著

     概要を見る

    The quantification of pathogens is important for assessing water safety and preventing disease outbreaks. Culture-independent approaches, such as quantitative PCR (qPCR) and digital PCR (dPCR), are useful techniques for quantifying pathogens in water samples. However, since pathogens are usually present at low concentrations in water, it is necessary to concentrate microbial cells before extracting their DNA. Many existing microbial concentration methods are inefficient or take a long time to perform. In this study, we applied a coagulation and foam separation method to concentrate environmental water samples of between 1000 and 5000 mL to 100 μL of DNA (i.e., a 1–5 × 104-fold concentration). The concentration process took <1 h. The DNA samples were then used to quantify various target pathogens using dPCR. One gene, the Shiga toxin gene (stx2) of Shiga toxin-producing Escherichia coli, was detected at 32 copies/100 mL in a river water sample. The coagulation and foam concentration method followed by dPCR reported herein is a fast, sensitive, and reliable method to quantify pathogen genes in environmental water samples.

    DOI

  • Growth and antibiotic resistance acquisition of Escherichia coli in a river that receives treated sewage effluent

    Suzuki Y., Hashimoto R., Xie H., Nishimura E., Nishiyama M., Nukazawa K., Ishii S.

    Science of the Total Environment   690   696 - 704   2019年11月  [査読有り]

    共著

     概要を見る

    © 2019 Elsevier B.V. Wastewater treatment plants could discharge Escherichia coli and antibiotic resistant bacteria to the environment adjacent to, or downstream of their discharge point. However, their discharge also contains nutrients which could promote growth of E. coli in water environments. This study was done to clarify the potential of growth and antibiotic resistance acquisition of E. coli in a river environment. Levels of E. coli were monitored in a river that receives treated sewage effluent for over four years. River water, periphyton and sediment samples were collected at sites upstream and downstream of treated sewage inflow. Concentrations of E. coli increased in river water and periphyton at the sites downstream of the treated sewage inflow, although levels of E. coli were very low or below detection limit in the treated sewage samples. Concentrations of Chlorophyll a increased at the downstream sites, likely due to nutrient input from the treated sewage. Based on pulsed field gel electrophoresis, identical genotype occurred at multiple sites both upstream and downstream of the treated sewage inflow. However, strains resistant to antibiotics such as ampicillin, cefazolin, ciprofloxacin, and chloramphenicol were more frequently obtained from the downstream sites than the upstream sites. Multidrug resistant E. coli strains were detected in periphyton and sediment samples collected at the downstream sites. Non-resistant strains with PDGE genotype identical to the multi-drug strains were also detected, indicating that E. coli might have become resistant to antibiotics by acquiring resistance genes via horizontal gene transfer. Laboratory incubation experiment showed the growth of E. coli in periphyton or sediment-fed river water samples. These results suggest that the wastewater treatment inflow did not directly provide E. coli to the river water, but could promote the growth of periphyton, which could lead to the elevated levels of E. coli and the emergence of antibiotic resistant E. coli.

    DOI

  • 宮崎県小丸川水系の底生動物の個体数変動における餌資源因子の影響評価

    糠澤桂,有働祐也,鈴木祥広

    土木学会論文集B1(水工学)     2019年11月  [査読有り]

    共著

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総説・解説記事 【 表示 / 非表示

  • ダム堆砂対策による河川生態系の応答に関する事例紹介

    糠澤桂,鈴木祥広

    電力土木     2020年01月  [依頼有り]

    総説・解説(学術雑誌)   共著

その他研究活動 【 表示 / 非表示

  • 小丸川水系生物調査

    フィールドワーク 

    2018年04月
    -
    継続中
     

学術関係受賞 【 表示 / 非表示

  • 第55回環境工学研究フォーラム 優秀ポスター発表賞

    2018年12月18日   土木学会  

    受賞者:  西村恵美,糠澤桂,鈴木祥広

  • 応用生態工学会第22回研究発表会 優秀ポスター研究発表賞

    2018年09月23日   応用生態工学会  

    受賞者:  糠澤桂

  • 平成28年度建設工学研究奨励賞

    2017年06月05日   一般財団法人建設工学研究振興会   宮崎における分布型汚濁流出モデルの開発とその利用による河川環境・生物多様性評価  

    受賞者:  糠澤桂

  • 第21回地球環境シンポジウム 優秀講演賞

    2014年09月   土木学会地球環境委員会  

    受賞者:  糠澤桂, 風間聡, 渡辺幸三

  • 平成24年度東北大学 工学研究科長賞

    2013年03月   東北大学  

    受賞者:  糠澤桂

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科研費(文科省・学振)獲得実績 【 表示 / 非表示

  • 蚊共生細菌ボルバキアによるデング熱の生態学的制御:安心・安価な新技術の提案

    国際共同研究加速基金(国際共同研究強化(B))

    研究期間:  2019年10月  -  2022年03月  代表者:  渡辺幸三

  • 流出解析に基づく流域一貫の河川生息場モデルの高度化: 流況と空間解像度に着目して

    若手研究

    研究期間:  2019年04月  -  2022年03月  代表者:  糠澤桂

  • インドネシア・バンドンのデング熱蚊の生態疫学:ウイルス伝播と気候変動影響の予測

    二国間交流事業共同研究

    研究期間:  2019年04月  -  2022年03月  代表者:  渡辺幸三

  • 健全な流砂系の回復によるサステナブル流域総合土砂管理の実証研究

    基盤研究(B)

    研究期間:  2017年04月  -  継続中  代表者:  赤松 良久

  • 蚊に着目したデングウイルスの空間伝播動態の解明と生態学的防御

    基盤研究(B)

    研究期間:  2016年04月  -  継続中  代表者:  渡辺 幸三

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その他競争的資金獲得実績 【 表示 / 非表示

  • 総合土砂管理による河川生態系への影響の定量的評価手法の開発

    提供機関:  民間財団等  河川基金

    研究期間: 2017年04月  -  2019年03月  代表者:  入江 光輝

受託研究受入実績 【 表示 / 非表示

  • 宮崎県小丸川流域における治水と生態系の総合評価のためのモデル開発

    提供機関: 国土交通省  一般受託研究

    研究期間: 2018年05月  -  2021年03月  代表者: 糠澤桂

寄附金・講座・研究部門 【 表示 / 非表示

  • 工学部研究奨学寄附金

    寄附者名称:西日本技術開発(株) 2020年01月

  • 工学部の研究のため

    寄附者名称:西日本技術開発(株) 2019年01月

  • 工学部の研究のため

    寄附者名称:西日本技術開発(株) 2018年01月

  • 工学部の研究のため

    寄附者名称:西日本技術開発(株) 2017年01月

研究発表 【 表示 / 非表示

  • 宮崎県小丸川水系の底生動物の個体数変動における餌資源因子の影響評価

    糠澤桂,有働祐也,鈴木祥広

    第64回水工学講演会  (さいたま市)  2019年11月  -  2019年11月    土木学会水工学委員会

  • Growth and antibiotic resistance acquisition of Escherichia coli in a river that receives treated sewage effluent

    Xie, H., Hashimoto, R., Nishimura, E., Nishiyama, M., Nukazawa, K., Suzuki, Y., Ishii, S.

    水環境技術会議  (大阪市)  2019年07月  -  2019年07月   

  • Fundamental study on optimum condition in super-high-speed coagulation and sedimentation using micro-sand

    Kaku R., Furuhashi, Y., Chuganji, N., Nukazawa, K., Suzuki, Y.

    水環境技術会議  (大阪市)  2019年07月  -  2019年07月   

  • Development of comprehensive detection method of pathogenic bacteria from river water combining foam concentration and bacterial flora analysis

    Shimizu, H., Jikumaru, A., Nukazawa, K., Masago, Y., Ogura, Y., Ishii, S., Suzuki, Y.

    水環境技術会議  (大阪市)  2019年07月  -  2019年07月   

  • A field study on antibiotic resistant Escherichia coli isolated from livestock, wild animals and wastewater in a stock farm

    Hiroki, H., Kobayashi, I., Sakamoto, S., Uemura, R., Nukazawa, K., Suzuki, Y.

    水環境技術会議  (大阪市)  2019年07月  -  2019年07月   

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