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学術研究成果リスト

Detail of Grant Awarded Academic Researches

Project

Systematic evaluation of nitrous oxide consumption potentials by sediments in the Tama River: The effect of treated water discharged from a municipal wastewater treatment plant

Academic
Research
No.360
Principal
Investigator
Akihiko TERADA
Affiliation Tokyo University of Agriculture and Technology
Research
Summary

This study hypothesizes that spots adjacent to the discharge points of municipal wastewater treatment plants (WWTPs) in the Tama River harbor bacteria capable of effectively consuming greenhouse gas nitrous oxide (N2O) and, hence, the N2O consumption activity. For the verification of this hypothesis, the work investigated the microbial community compositions, the abundances of functional genes responsible for N2O production and consumption, and the potentials of N2O consumption by river sediment. Water and sediment samples in the upstream and downstream of the Tama River were taken, subjected to the measurement of nitrogen constituents, the analyses of functional gene abundances and microbial community compositions, and the quantification of N2O consumption potentials. In the downstream direction, nitrate and dissolved N2O concentrations increased. Significantly, at spots near the discharge points of several WWTPs, these concentrations increased. The estimation of N2O consumption potentials of the sediments revealed that the potentials increased in the downstream river direction. Furthermore, inherent N2O consumption and production activities in the sediment right after WWTPs increased, indicating that it functions as both N2O source and sink. Molecular microbial analysis suggested that clade II type N2O-reducing bacteria were abundant than clade I type in the sediment. Moreover, bacteria responsible for ammonia oxidation and N2O production may be complete ammonia oxidizers. The microbial community composition analysis based on the 16S rRNA gene suggests the presence of low-abundant but unique N2O-reducing bacteria, indigenously inhabited in the river sediment. Collectively, this study illuminated that a discharge point of municipal wastewater treatment is important for N2O consumption and awaits the discovery of unexplored N2O-reducing bacteria.


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