Effects of natural and anthropogenic substances on atmospheric deposition in the Kyoto-Osaka-Kobe area using multi-isotope ratios

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K12359
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63040:Environmental impact assessment-related
• Research Institution: Doshisha University
• Principal Investigator: Yokoo Yoriko 同志社大学, 理工学部, 助教 (00334045)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 大気降下物 / ストロンチウム同位体 / ネオジウム同位体 / 硫黄同位体 / 鉛同位体 / 硝酸イオン / 濃縮係数 / 黄砂

Outline of Final Research Achievements

In order to evaluate the effect of natural and anthropogenic substances on atmospheric environment, elemental compositions and sulfur, lead, strontium and neodymium isotope ratios of monthly soluble particles (precipitation) and solid particles (dust) in rainwater samples were determined. Rainwater samples were collected in the Kyoto-Osaka-Kobe area.
These elemental and multi-isotopic compositions of monthly precipitation and dust in rainwater samples are useful index for the geological and anthropogenic substances and eolian dust originated from the Asian continent. The Sr-Nd isotope ratios of dust during spring showed the close value of Chinese loess which is an origin substance of yellow sand, and the mixing ratios between local and eolian dust could be estimated using these Sr-Nd isotope ratios. The Pb and sulfur isotope ratios of atmospheric depositions are useful tracer to evaluate for domestic and long-distance transported anthropogenic inputs.

Free Research Field

環境地球化学

Academic Significance and Societal Importance of the Research Achievements

一つの降水試料に対して元素・同位体組成をマルチ分析することで，起源の情報を蓄積し，地域また越境からの自然起源物質や人為起源物質の大気および地圏環境への影響を見積もることができた．特に硝酸やカルシウムといった主要陽陰イオンは，森林生態系への栄養塩元素である一方で降水の酸性度にも関わることから，長期間での大気からの降下量やその起源を見積ったデータは学術的意義があり重要である．
長期間の測定データは大気環境の変遷を読み解き，人為活動起源物質の流入状況が変化した前後の解析ができる試料およびデータの蓄積がされた点でも社会的意義があるといえる．