Diurnal variation of CO2 concentration, Δ14C and δ13C in an urban forest: estimate of the anthropogenic and biogenic CO2 contributions

Authors

  • Hiroshi A. Takahashi,

    Corresponding author
    1. Research Center for Deep Geological Environments, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8567, Japan;
      Corresponding author.
      e-mail: h.a.takahashi@aist.go.jp
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  • Eiichi Konohira,

    1. Division of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan;
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  • Tetsuya Hiyama,

    1. Hydrospheric Atmospheric Research Center, Nagoya University, Nagoya 464-8601, Japan;
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  • Masayo Minami,

    1. Division of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan;
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  • Toshio Nakamura,

    1. Center for Chronological Research, Nagoya University, Nagoya 464-8602, Japan;
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  • Naohiro Yoshida

    1. Department of Environmental Science and Technology, Tokyo Institute of Technology, also with CREST Project JST, Yokohama 226-8502, Japan
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Corresponding author.
e-mail: h.a.takahashi@aist.go.jp

Abstract

Diurnal variation in the atmospheric CO2 concentration and the carbon isotopic composition (Δ14C and δ13C) was measured in a forest in an urban area on 9 February 1999. The carbon isotope approach used in the present study differentiated between the quantitative contributions from anthropogenic and biogenic CO2 sources in the urban atmosphere. The anthropogenic (fossil fuel) and biogenic (soil respiration) contributions was estimated, and they ranged from 1 to 16% and from 2 to 8% of the total atmospheric CO2. The diurnal variation of the anthropogenic CO2 was the major cause of the total atmospheric CO2 variation, while the biogenic CO2 remained relatively constant throughout the day. Estimating the contribution of soil respired CO2 provided the mean residence time of soil respired CO2 within the forest atmosphere.

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