日本地球惑星科学連合2023年大会

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[E] オンラインポスター発表

セッション記号 A (大気水圏科学) » A-HW 水文・陸水・地下水学・水環境

[A-HW18] 流域圏生態系における物質輸送と循環:源流から沿岸海域まで

2023年5月25日(木) 10:45 〜 12:15 オンラインポスターZoom会場 (5) (オンラインポスター)

コンビーナ:細野 高啓(熊本大学大学院先端科学研究部)、伴 修平(公立大学法人 滋賀県立大学)、齋藤 光代(広島大学 大学院先進理工系科学研究科 )、Adina Paytan(University of California Santa Cruz)


現地ポスター発表開催日時 (2023/5/26 17:15-18:45)

10:45 〜 12:15

[AHW18-P09] Impact of Anthropogenic phosphorus loading on authigenic apatite in marine sediment of Osaka Bay

*Muhammad Shahinur Rahman1Shin-ichi Onodera1Takuya Ishida1Mitsuyo Saito1Kunyang Wang1Takahiro Hosono2Yu Umezawa3 (1.Hiroshima University、2.Kumamoto University、3.Tokyo University of Agriculture and Technology)

キーワード:Limiting factor, Eutrophication, Urbanized Bay, SEDEX, Phosphorus species

Phosphorus is one of the most important limiting factors for coastal productivity. In recent years, due to the population growth and extensive use of phosphorus derived chemicals like fertilizer creates an enormous problem named eutrophication in many coastal regions along with nitrogen. It is important to know the accumulation and release pattern of phosphorus for better management planning.

This study was performed in Osaka Bay which is an urbanized enclosed bay and one of the most industrial regions of Japan. We analyze phosphorus concentrations in the sediment core of Osaka Bay using the sequential extraction method (SEDEX) for understanding the historical phosphorus loads from watersheds and phosphorus accumulation in the sediment, especially calcium bound authigenic apatite which characteristics is generally non-reactive and important for P accumulation. The 210Pb method was used for determination of the sediment core chronology.
The mean concentration of Ca-P is 99.7 ± 24.4 with a range of 55.7 to 149.9 mg/Kg. The value of Authigenic Apatite has stable since 1920, and a positive trend has seen which apex was after 1960. We also evaluate the relationship between depth distribution of Authigenic Apatite and historical total phosphorus loading from Yamato River estimated by Soil and Water Assessment Tool (SWAT). We divided data on total phosphorus loading into two subsets considering environmental law enforcement. Before 1970 there was less environmental law enforcement in Japan. There was a positive relationship between total phosphorus loading and Authigenic Apatite in 1940-1970 which converted to negative correlation after 1970. We also evaluate the sediment texture pattern and the Authigenic Apatite. We find that the sand percentage has increased comparatively after 1970. We assume sand particles contribute to the increase of Authigenic Apatite during this period.

Acknowledgement: This study supported by Asia-Pacific Network for Global Change Research Project (CRRP2019-09MY-Onodera).