{"created":"2024-03-14T02:17:56.189397+00:00","id":2000075,"links":{},"metadata":{"_buckets":{"deposit":"d205da73-8ced-4f1b-b14e-54bcb91a4cf2"},"_deposit":{"created_by":12,"id":"2000075","owner":"12","owners":[12],"pid":{"revision_id":0,"type":"depid","value":"2000075"},"status":"published"},"_oai":{"id":"oai:repository.naro.go.jp:02000075","sets":["1706970004180:1","87:661:1727312983899:663:1709881364343"]},"author_link":[],"item_12_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2005-03-31","bibliographicIssueDateType":"Issued"},"bibliographicPageEnd":"119","bibliographicPageStart":"111","bibliographicVolumeNumber":"203","bibliographic_titles":[{"bibliographic_title":"農業工学研究所技報","bibliographic_titleLang":"ja"},{"bibliographic_title":"Technical report of the National Research Institute of Agricultural Engineering","bibliographic_titleLang":"en"}]}]},"item_12_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"In Japan, an irrigation project with construction of 147 tube wells and two subsurface dams which store 20,000,000m3 of groundwater had started in 1987 and had completed in 2001 in Miyakojima Island. The island consists of Quaternary limestone with a high permeability and basement of Tertiary mudstone. Concentration of nitrate nitrogen in groundwater had been monitored at the typical observation wells in the reservation area of subsurface dam every month since 1975. Concentration of nitrate nitrogen and electric conductivity in groundwater were also measured at 39 wells in 2000 and 2003. The fluctuation of concentration of nitrate nitrogen in groundwater showed three features. 1） The concentration of nitrate nitrogen in the groundwater increased gradually, and was 11mg/l in 1988; afterward the concentration of nitrate nitrogen in the groundwater decreased gradually, and was 9mg/l in 2001. The amount of the fertilizer sales was the largest in 1982 in the Island. These results suggest that the nitrate nitrogen of the fertilizer origin infiltrated to groundwater table in six years. 2） Monthly fluctuation of the concentration of nitrate nitrogen in groundwater had decreased after the completion of the subsurface dam. The fluctuation of the nitrate-nitrogen concentration would depend on the dilution caused by a lot of precipitation in typhoon and rainy season. The result shows that the fluctuation of the concentration of nitrate nitrogen in groundwater by the dilution decreased because the amount of the storage groundwater increased. 3） The concentration of nitrate nitrogen in groundwater increased partially around the cut-off wall after the construction of the subsurface dam. After groundwater began to be used, the concentration of nitrate nitrogen in the groundwater around the cut-off wall was almost same as the concentration of surrounding. The reason for this change would be that the groundwater flowed faster by pumping. These three results suggest that the fluctuation of the concentration of nitrate nitrogen in groundwater can be understood by few monitoring after the subsurface dam is completed.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"地下ダムは，帯水層の空隙に地下水を蓄える施設であり，地下水の持続的な利用を可能にすると共に，地上ダムと異なり，水を貯留するために陸を水没させない，災害を被る危険がない等の長所を持つ。世界では，小規模な地下ダムがアフリカ，インド，中国などの乾燥地域で実用化されている（Hanson and Nilsson 1986）。日本においても1970年代の貯水量40万m3クラスの皆福実験地下ダムの施工を経て（沖縄総合事務局1 9 8 3），1980年代後半から潅漑のために南西諸島および奄美諸島で地下ダム事業が開始された（Nagata et al. 1993）。沖縄県をはじめとするこれら琉球石灰岩分布地域は，帯水層の有効間隙率が大きく地下水の貯留に適しているため，現在国および県によって数々の大規模地下ダムが施工されている。一方，1980年代後半から着工されてきたこれらの地下ダムは，次々と完工の時期を迎えている。地下ダムの建設によって地下水位は数十メートル上昇し，不飽和帯の厚さは従前の半分以下になった。自然状態の地下水流を止水壁で遮ることによって地下水は滞留し，用水は確保されたが，同時に既往の地下水流動環境が大きく変化した。この変化は地下水の流動経路や水質に影響を及ぼすことが予想されるが，世界的に研究例が少なく，流域の適切な地下水保全計画の策定を難しくしている（今泉ら2002）。地下ダムの築造による地域の地下水環境変化を明らかにすることは喫緊の課題である。\n一般的に石灰岩に代表される溶解性炭酸塩岩類から成る帯水層は，非溶解性岩類中の帯水層と比べて水の循環と岩石の融解によって， 透水性が偏在している。Legrand and Stringfield（1971）は炭酸塩帯水層の構造について次の様に総括している。（1）水の循環と溶解活動は飽和帯の上部で最も大きく，深さが増加するにつれて小さくなる傾向がある。（2）不飽和帯において浸透水の流路となっている開口部は，溶解作用で拡大する傾向があるが，浸透水の流路となってない比較的小さな開口部は溶解作用によってほとんど拡大しない。この様な溶解チャンネル網は飽和帯の上部で特に発達している。Eric et al.（2002）は，アメリカアーカンソー州のカルスト地帯の地下水盆において，地下水流出域の湧水および土壌に含まれる硝酸濃度を定期的に測定し，肥料によってもたらされる硝酸の74％が土壌マトリクスの中を極めて遅い速度（65cm/y）で降下浸透し，26％が嵐によって発生する土壌中の大間隙流によって，より低濃度で素早く地下水に付加されることを明らかにした。\n宮古島においては地下ダムの建設前，地下水中の硝酸態窒素濃度はおよそ10mg/lであった。その濃度は日本の飲料水基準の上限である。地下水の水質，特に硝酸汚染は宮古島の人々にとって最も関心の高い問題の1つとなっている。\n本研究では流域の適切な地下水保全計画の策定に資するため，止水壁が完成した沖縄県宮古島の地下ダム流域内の39箇所の地下水観測孔において，窒素濃度，電気伝導度を深度毎に測定し，地下ダム完成前の値と比較するとともに，流域内の長期的な水質測定結果と，島内の肥料販売量の推移を比較し，水質環境の変化を解明した。","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_12_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.24514/0002000075","subitem_identifier_reg_type":"JaLC"}]},"item_12_publisher_8":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"独立行政法人農業工学研究所","subitem_publisher_language":"ja"},{"subitem_publisher":"NATIONAL INSTITUTE FOR RURAL ENGINEERING INDEPENDENT ADMINISTRATIVE INSTITUTION","subitem_publisher_language":"en"}]},"item_12_source_id_9":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"0915-3314","subitem_source_identifier_type":"ISSN"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"ISHIDA, Satoshi","creatorNameLang":"en"},{"creatorName":"石田, 聡","creatorNameLang":"ja"},{"creatorName":"イシダ, サトシ","creatorNameLang":"ja-Kana"}],"familyNames":[{"familyName":"ISHIDA","familyNameLang":"en"},{"familyName":"石田","familyNameLang":"ja"},{"familyName":"イシダ","familyNameLang":"ja-Kana"}],"givenNames":[{"givenName":"Satoshi","givenNameLang":"en"},{"givenName":"聡","givenNameLang":"ja"},{"givenName":"サトシ","givenNameLang":"ja-Kana"}],"nameIdentifiers":[{"nameIdentifier":"30414444","nameIdentifierScheme":"e-Rad","nameIdentifierURI":"https://kaken.nii.ac.jp/ja/search/?qm=30414444"},{"nameIdentifier":"ishidast","nameIdentifierScheme":"researchmap","nameIdentifierURI":"http://researchmap.jp/ishidast"}]},{"creatorNames":[{"creatorName":"TSUCHIHARA, Takeo","creatorNameLang":"en"},{"creatorName":"土原, 健雄","creatorNameLang":"ja"},{"creatorName":"ツチハラ, タケオ","creatorNameLang":"ja-Kana"}],"familyNames":[{"familyName":"TSUCHIHARA","familyNameLang":"en"},{"familyName":"土原","familyNameLang":"ja"},{"familyName":"ツチハラ","familyNameLang":"ja-Kana"}],"givenNames":[{"givenName":"Takeo","givenNameLang":"en"},{"givenName":"健雄","givenNameLang":"ja"},{"givenName":"タケオ","givenNameLang":"ja-Kana"}],"nameIdentifiers":[{"nameIdentifier":"30399365","nameIdentifierScheme":"e-Rad","nameIdentifierURI":"https://kaken.nii.ac.jp/ja/search/?qm=30399365"},{"nameIdentifier":"tsuchihara","nameIdentifierScheme":"researchmap","nameIdentifierURI":"http://researchmap.jp/tsuchihara"}]},{"creatorNames":[{"creatorName":"IMAIZUMI, Masayuki","creatorNameLang":"en"},{"creatorName":"今泉, 眞之","creatorNameLang":"ja"},{"creatorName":"イマイズミ, マサユキ","creatorNameLang":"ja-Kana"}],"familyNames":[{"familyName":"IMAIZUMI","familyNameLang":"en"},{"familyName":"今泉","familyNameLang":"ja"},{"familyName":"イマイズミ","familyNameLang":"ja-Kana"}],"givenNames":[{"givenName":"Masayuki","givenNameLang":"en"},{"givenName":"眞之","givenNameLang":"ja"},{"givenName":"マサユキ","givenNameLang":"ja-Kana"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2024-03-14"}],"displaytype":"detail","filename":"TRNIREJ203_111-119.pdf","filesize":[{"value":"377 KB"}],"format":"application/pdf","license_note":"©　 国立研究開発法人 農業・食品産業技術総合研究機構\nNational Agriculture and Food Research Organization, Japan","licensetype":"license_note","url":{"url":"https://repository.naro.go.jp/record/2000075/files/TRNIREJ203_111-119.pdf"},"version_id":"c956ae34-16cf-48dd-93f8-7334a82231b0"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"沖縄県宮古島の地下ダムにおける地下水中の硝酸態窒素濃度の変化について","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"沖縄県宮古島の地下ダムにおける地下水中の硝酸態窒素濃度の変化について","subitem_title_language":"ja"},{"subitem_title":"Fluctuation of Concentration of Nitrate Nitrogen in Groundwater of Reservoir Area of Subsurface Dam in Miyakojima Island, Japan","subitem_title_language":"en"}]},"item_type_id":"12","owner":"12","path":["1709881364343","1"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2024-03-14"},"publish_date":"2024-03-14","publish_status":"0","recid":"2000075","relation_version_is_last":true,"title":["沖縄県宮古島の地下ダムにおける地下水中の硝酸態窒素濃度の変化について"],"weko_creator_id":"12","weko_shared_id":-1},"updated":"2024-04-04T07:54:45.974802+00:00"}