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Journal of Environmental Quality Abstract - Surface Water Quality

Influence of Irrigated Paddy Fields on the Fluorescence Properties of Fluvial Dissolved Organic Matter


This article in JEQ

  1. Vol. 40 No. 4, p. 1266-1272
    Received: Aug 25, 2010

    * Corresponding author(s): maie@vmas.kitasato-u.ac.jp
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  1. Youichiro Abea,
  2. Nagamitsu Maie *b and
  3. Eikichi Shimab
  1. a Graduate School of Veterinary Medicine & Animal Sciences, Kitasato Univ., Towada, Aomori Prefecture 034-8628, Japan
    b School of Veterinary Medicine, Kitasato Univ., Towada, Aomori Prefecture 034-8628, Japan. Assigned to Associate Editor Robert Cook


This study investigated seasonal and geographical variation in the fluorescence properties of dissolved organic matter (DOM) in a river system that includes rice paddy fields in its watershed. The river system covers a northern area of the main island of Japan, and between 6 and 45% the watershed area of the tributaries is paddy fields. Water samples were collected monthly from eight tributaries for 1 yr, and the fluorescence properties of DOM were monitored by combined excitation-emission matrix (EEM) and parallel factor analysis. The EEM was statistically decomposed into six fluorescence components with different environmental dynamics. The relative proportion of these components varied with season and geographic location, the former having a greater effect than the latter. Seasonal variation is largely attributed to changes in the source of DOM associated with irrigated rice cultivation practice. The fluorescence component composition showed a stronger autochthonous signature, which varied over a wider range during off-cropping period (October–April) than cropping period (May–September). During the cropping period, a large amount of allochthonous DOM with relatively similar quality was transported into river water from flooded paddy fields and masked the variability in the quality of DOM among tributaries. Therefore, irrigated rice cropping practices are considered to be one of major factors that influence seasonal and geographical variation of fluvial DOM composition.

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