Oxygen isotope analysis of phosphate toward reducing potential risks of water degradation in public waters in the hilly and mountainous area

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K16115
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: Kyushu University
• Principal Investigator: Ide Jun'ichiro 九州大学, 持続可能な社会のための決断科学センター, 助教 (70606756)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 面減汚濁 / 富栄養化 / 安定同位体比 / 流出起源 / 流域 / McLaughlin法 / 水文条件

Outline of Final Research Achievements

This study sought to characterize oxygen isotope ratio of river phosphate (δ18Op) and examined dynamics of river phosphate in the hilly and mountainous area. River water samples were collected, and their δ18Op were analyzed in the hilly and mountainous, the urbanized and the agricultural flat areas. A comparison of δ18Op among the three areas showed that the mean δ18Op value was highest in the agricultural flat area, and was similar between the hilly and mountainous and the urbanized areas. Variability of δ18Op values during the observation period was larger in the hilly and mountainous area than in the other two areas. Additionally, δ18Op tended to converge to a low value as the antecedent precipitation index increased. It is predicted that river phosphate with low δ18Op was exported from upper forested areas into the downstream rivers particularly during high flow conditions in the hilly and mountainous area.

Free Research Field

森林水文学