Estimation of source contribution to nitrate loading in road runoff using stable isotope analysis |
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| Authors: | K. Kojima S. Sano F. Kurisu H. Furumai |
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| Affiliation: | 1. Research Center for Water Environment Technology, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan;2. Institute of Technology, SHIMIZU CORPORATION, Etchujima, Koto-ku, Tokyo, Japan;3. Mizuho Information &4. Research Institute, Inc., Kanda-Nishikicho, Chiyoda-ku, Tokyo, Japan |
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| Abstract: | The nitrogen load was determined in road runoff during rainfall events. Moreover, nitrate isotopes analysis was conducted to determine the contribution of nitrates from atmospheric deposition and leaching from road dust. The concentrations of NO3-N in road runoff were higher than those in atmospheric deposits for each rainfall event, except one event with a long antecedent dry weather period. The δ18O-NO3 in road runoff was lower than in atmospheric deposits and higher than in leachate from road dust; however, no difference in δ15N-NO3 was observed. By using δ18O-NO3 as an indicator for evaluating NO3-N sources in road runoff, contribution ratios of NO3-N from road dust were estimated to be 14–22%, 23–25%, and 22–34% for Event 1 to Event 3, respectively. These results indicated that the NO3-N from the atmosphere accounts for more than half of the NO3-N in road runoff. |
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| Keywords: | Isotope analysis nitrate nonpoint pollution road runoff source determination |
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