10:45 AM - 12:15 PM
[AHW18-P09] Impact of Anthropogenic phosphorus loading on authigenic apatite in marine sediment of Osaka Bay
Keywords: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).
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).