水田における水質浄化機能発現の灌漑用水の境界点濃度  [in Japanese] Expression Levels of Irrigation Water Boundary Concentration in the Paddy Field Water Purification Function  [in Japanese]

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Abstract

水田における窒素の浄化は,浸透型の場合には灌漑水等がある一定以上のT-N濃度であればほぼ比例してT-N除去量が増大し,逆にそれ以下の低濃度の場合には汚濁源として作用すること,すなわち,見かけ上において浄化も汚濁もしない灌漑水の境界点濃度が存在し,それがおおよそ1.5mg/L~2.0mg/Lとされている。ちなみに,T-Pでは0.24mg/L~0.25mg/Lである。本調査研究では,印旛沼水を灌漑用水として浸透掛流灌漑を実施している1.7haの水田において,T-N,T-Pの他にNO<sub>3</sub>-NとCODについて灌漑水等の境界点濃度を明らかにし,さらに調査水田土壌をカラムに充填して調査結果の再現性を検討した。その結果,既往の成果並びに調査とカラム実験値とが近似し,その再現性,信憑性が確認された。

The removal amount of nitrogen at a percolation spill-over irrigation paddy field has been increasing proportionally to more than a certain T-N concentration of irrigation water concentration. The other side, not more than that certain concentration was affected by water pollutants. That is to say the paddy field has a boundary concentration which is the irrigation water concentration in which neither purification nor contamination appear. The T-N boundary concentration is 1.5mg/L - 2.0mg/L, although, T-P is 0.24mg/L - 0.25mg/L. In this research study, we investigated the boundary concentration of T-N,T-P,NO<sub>3</sub>-N and COD in a percolation spill-over irrigation paddy field which has an area of 1.7 hectare, and uses Inba lake water for irrigation. Also, we examined a column experiment used to study the field's soil to reproduce the result at field test. As a result, the field research and column experiment were an approximated concentration of past reports. So, we confirmed reproducibility and credibility.

Journal

  • Papers on Environmental Information Science

    Papers on Environmental Information Science ceis25(0), 281-286, 2011

    Center for Environmental Information Science

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