Watershed Soils and land use characteristics affecting the river runoff processes in terms of P and N concentrations
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- MIURA Shingo
- Buyodo corporation National Institute for Environmental Studies
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- KOHZU Ayato
- National Institute for Environmental Studies
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- IMAI Akio
- National Institute for Environmental Studies
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- KOMATSU Kazuo
- National Institute for Environmental Studies
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- SHINOHARA Ryuichiro
- National Institute for Environmental Studies
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- KAWASAKI Nobuyuki
- Faculty of Science and Biotechnology, Universiti Selangor
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- SATO Takayuki
- National Institute for Environmental Studies
Bibliographic Information
- Other Title
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- 流域特性(黒ボク・非黒ボク・土地利用)が支配するP, Nの河川流出プロセス
Abstract
<p> Phosphorus (P) and nitrogen (N) concentrations were measured at 75 points in the upper reaches of rivers draining into the agricultural watersheds south of the Ibaraki prefecture during the summer and winter of year 2009. A geographic information system (GIS) was used to combine the environmental information regarding the watersheds such as land use, topography, and soil with water quality data for a statistical analysis. As andosols have a stronger tendency to adsorb P than other soil types, watersheds were classified into areas with andosol and non-andosol soils. No correlation was observed between land use or topography and the P levels in the rivers for andosol areas, whereas a positive correlation was observed between the proportion of the built areas or paddy fields in the watersheds and the P levels in the rivers for non-andosol soil areas. These results indicate that a difference in the adsorption property among soils is an extremely important environmental factor affecting the P discharge process. Although the differences related to the soil type were not observed for N, there was an extremely strong positive correlation between the N levels in the rivers and the proportion of fields in the watersheds: summer N concentration declined greatly for watersheds with a high proportion of dry fields. These results clarified that dry fields are the major sources of N, but they could also act as N sink during summer. In watersheds with soils other than andosols, the effects of land use and seasonal changes on the load sources were relatively large in terms of the P and N discharge processes. It was difficult to discern the effects of topography, and a correlation between the nutrient concentrations and TWI (Topographic Wetness Index) was observed only for a few cases.</p>
Journal
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- Japanese Journal of Limnology (Rikusuigaku Zasshi)
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Japanese Journal of Limnology (Rikusuigaku Zasshi) 77 (1), 25-38, 2015
The Japanese Society of Limnology
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Details 詳細情報について
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- CRID
- 1390282679037432576
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- NII Article ID
- 130005397200
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- ISSN
- 18824897
- 00215104
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- Text Lang
- ja
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- Data Source
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- JaLC
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed