17:15 〜 19:15
[AHW27-P14] Vertical Distribution of Phosphorus Species in a Sediment Core in Jakarta Bay
キーワード：Sediment core, Eutrophication, Nutrient cycling, Urbanization, Phosphorus Species
Jakarta Bay, a semi-enclosed coastal ecosystem, is heavily influenced by anthropogenic activities, particularly nutrient inputs from urban and industrial sources. Phosphorus (P) is a key nutrient driving eutrophication in the bay, yet its speciation and distribution in sediments remain poorly understood. This study analyzes a 60 cm sediment core from Jakarta Bay to investigate the vertical distribution of phosphorus species. Sequential extraction techniques were employed to quantify five different P fractions: exchangeable P (Ex-P), iron-bound P (Fe-P), calcium-bound P (Ca-P), detrital apatite P (Det-P), and organic P (Org-P), while sediment dating provided a temporal framework for P accumulation.
The results reveal distinct trends in P speciation with depth, reflecting changes in external P loading and sedimentation processes over time. Ex-P shows a clear trend, with higher concentrations in the upper layers and a decline with depth, suggesting active remobilization and potential bioavailability. Fe-P remains relatively stable throughout the sediment profile but exhibits a mid-depth peak, possibly linked to diagenetic Fe cycling. Ca-P increases with depth, indicating long-term phosphorus sequestration in more stable mineral forms. Det-P, being inert, does not exhibit a noticeable trend, suggesting a stable supply from the source. Organic P is concentrated in the upper layers and decreases with depth due to organic matter decomposition. Total phosphorus (TP) gradually decreases with increasing depth, signifying progressive burial and phosphorus stabilization.
These findings highlight the role of sediments as a sink for phosphorus and provide insights into the long-term impacts of nutrient loading on Jakarta Bay's ecosystem. This study underscores the importance of managing external P inputs to mitigate eutrophication and improve water quality in the bay.
Acknowledgment
This study is supported by the Asia-Pacific Network for Global Change Research Project (CRRP2019-09MY-Onodera) and JSPS Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)) (PI: Shin-ichi Onodera, 2021-2024) and funding by the Japan International Cooperation Agency (JICA) Agriculture Studies Networks for Food Security (Agri-Net) program.
The results reveal distinct trends in P speciation with depth, reflecting changes in external P loading and sedimentation processes over time. Ex-P shows a clear trend, with higher concentrations in the upper layers and a decline with depth, suggesting active remobilization and potential bioavailability. Fe-P remains relatively stable throughout the sediment profile but exhibits a mid-depth peak, possibly linked to diagenetic Fe cycling. Ca-P increases with depth, indicating long-term phosphorus sequestration in more stable mineral forms. Det-P, being inert, does not exhibit a noticeable trend, suggesting a stable supply from the source. Organic P is concentrated in the upper layers and decreases with depth due to organic matter decomposition. Total phosphorus (TP) gradually decreases with increasing depth, signifying progressive burial and phosphorus stabilization.
These findings highlight the role of sediments as a sink for phosphorus and provide insights into the long-term impacts of nutrient loading on Jakarta Bay's ecosystem. This study underscores the importance of managing external P inputs to mitigate eutrophication and improve water quality in the bay.
Acknowledgment
This study is supported by the Asia-Pacific Network for Global Change Research Project (CRRP2019-09MY-Onodera) and JSPS Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)) (PI: Shin-ichi Onodera, 2021-2024) and funding by the Japan International Cooperation Agency (JICA) Agriculture Studies Networks for Food Security (Agri-Net) program.