論文

査読有り 国際誌
2019年11月10日

Isotopic evidence for seasonality of microbial internal nitrogen cycles in a temperate forested catchment with heavy snowfall.

The Science of the total environment
  • Shohei Hattori
  • ,
  • Yoshio Nuñez Palma
  • ,
  • Yuko Itoh
  • ,
  • Moeko Kawasaki
  • ,
  • Yoichi Fujihara
  • ,
  • Keiji Takase
  • ,
  • Naohiro Yoshida

690
開始ページ
290
終了ページ
299
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1016/j.scitotenv.2019.06.507
出版者・発行元
Elsevier {BV}

The Hokuriku district of central Japan receives high levels of precipitation during winter, largely in the form of snow. This study aimed to elucidate the internal nitrogen dynamics in this temperate forested region with heavy snowfall using the triple oxygen and nitrogen isotopic compositions of NO3-. The isotopic compositions of NO3- in atmospheric depositions (P and Tf), with terrestrial components of the soil layer (A0, S25, S55, and S90), ground water (G), and output (St) were measured from 2015 to 2016 in a forested catchment located in the southern area of the Ishikawa Prefecture, Japan. Seasonal distributions of Δ17O(NO3-) showed a decreasing trend from the inputs to outputs of the ecosystem. We found relatively constant Δ17O(NO3-) values in the output components (G and St), but found highly fluctuating Δ17O(NO3-) values resulting from the seasonal variations in the nitrification activity within soil waters. Specifically, we observed a lower nitrifying activity in the top soil layer throughout cold periods, presumably due to the input of cold melted snow water. The general trend of increasing δ15N(NO3-) value from the input to output components, with the changes in denitrification hotspots from shallow to deeper soil layer, can be observed between warm and cold periods. Thus, the seasonal changes of hotspots related to microbial nitrification and denitrification could be noted due to the seasonal changes in the isotopic compositions of nitrate. The estimated ecosystem-scale gross nitrification and denitrification rates are low; however, the output components are relatively stable with low concentrations of nitrate, indicating that the plant uptake of nitrogen most probably occurs at greater rates and scales in this forested ecosystem. Future nitrogen deposition and the vulnerable dynamics of snow melting are likely to have impactful consequences on such localities.

リンク情報
DOI
https://doi.org/10.1016/j.scitotenv.2019.06.507
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/31291607

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