Understandings of the determining factor of oceanic N2O emissions by using a marine ecosystem isotopomer model

2014 Fiscal Year Final Research Report

• Project/Area Number: 24740365
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geochemistry/Astrochemistry
• Research Institution: Japan Agency for Marine-Earth Science and Technology (2013-2014); Tokyo Institute of Technology (2012)
• Principal Investigator: YOSHIKAWA Chisato 独立行政法人海洋研究開発機構, 生物地球化学研究分野, 技術研究員 (40435839)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 同位体分子種 / 海洋生態系モデル / 一酸化二窒素 / 海洋窒素循環

Outline of Final Research Achievements

A marine ecosystem model that incorporates nitrous oxide (N2O) production processes (i.e., ammonium oxidation during nitrification and nitrite reduction during nitrifier denitrification) and N isotopomers was developed to estimate the sea-air N2O flux and to quantify N2O production processes. This model was applied to surface water at two contrasting time series sites, a subarctic station (K2) and a subtropical station (S1) in the western North Pacific. The model was validated with observed N concentration and N isotopomer datasets, and successfully simulated the higher N2O concentrations. The annual mean N2O emissions were estimated to be 32.3 mgNm－2yr－1 at K2 and 2.7 mg Nm－2yr－1 at S1. The results of case studies based on this model suggested that N2O was mainly produced via ammonium oxidation at K2 but was produced via both ammonium oxidation and nitrite reduction at S1.

Free Research Field

生物地球化学