近自然小河川における抽水植物の浄化機能に関する研究  [in Japanese] Study on the Purification Function of Emerged Plants in Small Semi-natural Rivers  [in Japanese]

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Abstract

代表的な抽水植物であるマコモ (<I>Zizania latifolia</I>) が生育する, 都市近郊の近自然小河川において, 表流水および土壌間隙水の栄養塩量の変化の測定によるマコモの浄化機能の把握, マコモの刈り取りにおける栄養塩の総除去量の推定, の2つの調査を通じて, 今後の河川における浄化対策について検討を行った。その結果, 近自然小河川における抽水植物の浄化機能は, 表流水には確認できず, 夏期の土壌間隙水に対して現れることが明らかになった。また, 抽水植物による浄化機能が有効性を示しうるのは, 汚濁の進行していない河川であることが, 刈り取りによる栄養塩除去量の推定により推測された。

The aims of this study were 1) to clarify the purification function of an immersed plant, indian rice (makomo in Japanese: <I>Zizania latifolia</I> Trucz.) by monitoring the water-quality change in open-water and porewater, and 2) to estimate the possible amount of nutrient removal from river system by reaping <I>Z. latifolia</I>. The study area was selected in a small semi-natural river, the Juuroh-gawa River located in suburbs of Kohfu, Yamanashi. Water quality of open-water was measured at three points in the middle of the river course from upstream to downstream through a year, in whose intervals <I>Z. latifolia</I> were dominated along the river side. Porewater for the analysis were sampled in summer and winter from inside of <I>Z. latifolia</I> growing riverbeds and none-vegetation ones as contradistinctions, where water depth and flux were as similar as the former ones. In results, water quality of open-water had no change among three points; purification function of the species was not clear. In the result of porewater, however, total N was lower in <I>Z. latifolia</I> growing sites significantly than none-vegetation ones especially in summer. This means habitats of the species have purification function when the species grows. Additionally the maximum amount of nutrient absorption of the species was measured by analyzing the nutrient contents in the aboveground biomass reaped in summer when the growth is reached to the maximum. In the result, per cover area contents of N and P were 82 gNm<SUP>-2</SUP> and 26 gPm<SUP>-2</SUP> respectively. When the absorption rate during growing period was compared to other species after previous researches, these values were similar to the results of other immersed plants measured under field conditions. However, when the possible amount of nutrient removal from river system was estimated under the hypothesis that all individuals of the species growing within study area could be reaped and brought out from riverbeds, it was considered to be too low to purify all effluent loadings run into from the catchments area. It was concluded that <I>Z. latifolia</I> and its growing habitat have purification function, but it would be effective in the case just degree of eutrophication is low.

Journal

  • Journal of The Japanese Institute of Landscape Architecture

    Journal of The Japanese Institute of Landscape Architecture 66(4), 320-326, 2003-03-28

    The Japanese Institute of Landscape Architecture

References:  35

Cited by:  2

Codes

  • NII Article ID (NAID)
    110004308401
  • NII NACSIS-CAT ID (NCID)
    AN10455955
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    13408984
  • NDL Article ID
    6547502
  • NDL Source Classification
    ZK2(芸術--建築)
  • NDL Call No.
    Z11-315
  • Data Source
    CJP  CJPref  NDL  NII-ELS  IR  J-STAGE 
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