Source estimation of NOx in forest ambient air using nitrogen isotopic composition

2016 Fiscal Year Final Research Report

• Project/Area Number: 26660131
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Forest science
• Research Institution: National Institute for Environmental Studies
• Principal Investigator: Watanabe Mirai 国立研究開発法人国立環境研究所, 地域環境研究センター, 主任研究員 (50455250)
• Co-Investigator(Renkei-kenkyūsha): Koba Keisuke 国立大学法人京都大学, 生態学研究センター, 教授 (90311745) ; Nishina Kazuya 国立研究開発法人 国立環境研究所, 地域環境研究センター, 主任研究員 (60637776)
• Research Collaborator: Murata Eriko
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 窒素酸化物 / 窒素安定同位体比 / 窒素飽和

Outline of Final Research Achievements

In this study, we developed a new method to measure nitrogen isotopic composition of nitrogen oxides (δ15N-NOx) in actual environments. This method can capture the NOx quantitatively by the filter pack method, and analyze δ15N-NOx without fractionations by the denirifier method. We applied this method to trace the source of NOx in ambient air of a nitrogen-saturated forest. The field experiments showed that δ15N-NOx in forest ambient air was lower than δ15N-NOx in urban ambient air but higher than δ15N-NOx released from soils. Two-source mixing model suggested that forest NOx consisted of 81% of urban NOx and 19% of soil-released NOx.

Free Research Field

土壌学