An eco-balance approach to the evaluation of historical changes in nitrogen loads at a regional scale |
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Authors: | Sonoko D Kimura Ryusuke Hatano |
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Institution: | 1. Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei 183-8588, Japan;2. Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan |
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Abstract: | Historical changes in nitrogen flows of a municipality from 1912 to 2002 were analyzed to evaluate the relation between production and environmental pollution. The system comprised human, livestock and farmland subsystems. The indicators used in this study were production, surplus nitrogen (N) on farmland and total systems, and flow indices. Flow indices consist of cycling index (CI), export index (EI), and loss index (LI). CI was defined as the proportion of nitrogen cycled in the system to the total system throughflow, EI as nitrogen exported from the system, and LI as nitrogen lost from the system (sum of field surplus nitrogen, nitrogen in non-utilized excreta, and N2O and NH3 emissions). |
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Keywords: | Eco-balance Environment impact Land use Regional N flow Historical change Reactive nitrogen Flow indices |
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