11:00 AM - 1:00 PM
[HTT18-P02] Water and material circulation through the Toyama Deep-Sea Channel using the geochemical tracer: Attempts at interpretation
Keywords:Toyama Deep-Sea Channel, Deep current structure
The Toyama Deep-Sea Channel (TDSC) is the most significant submarine canyon in the seas around Japan, extending about 750 km north from Toyama Bay. It is known that a good fishing ground called “Aigame” exists in Toyama Bay, and the TDSC may be a nutrient transport channel from the land to the sea. Recent geophysical observations have shown that the direction of deep-sea currents differs between the east and west slopes of the TDSC, suggesting that the TDSC is also important from the perspective of materials transport from the sea to Toyama Bay. Therefore, this study aims to understand the water mass structure of the TDSC from chemical data of seawater and surface sediments and to clarify the circulation of terrestrial and marine materials transported through the TDSC.
Seawater and sediment samples were collected along the cross-section across the TDSC in May 2021. The nutrient concentrations in seawater and major element compositions, stable isotope ratios of organic carbon and nitrogen, and their contents in sediments were measured and compared with the observed data (temperature, salinity, dissolved oxygen, etc.). Significant differences in dissolved oxygen and nutrient concentrations were observed between the east and west slopes of the TDSC, and the results are consistent with the direction of ocean currents reported in previous studies. The Mn/Al ratio of the sediments, as an indicator of the reduction reactions, also supports the results.
In this presentation, we will discuss the land-sea material cycle in the TDSC, focusing on the analysis of organic carbon and nitrogen isotope ratios in surface sediments and nutrient dynamics in seawater.
Seawater and sediment samples were collected along the cross-section across the TDSC in May 2021. The nutrient concentrations in seawater and major element compositions, stable isotope ratios of organic carbon and nitrogen, and their contents in sediments were measured and compared with the observed data (temperature, salinity, dissolved oxygen, etc.). Significant differences in dissolved oxygen and nutrient concentrations were observed between the east and west slopes of the TDSC, and the results are consistent with the direction of ocean currents reported in previous studies. The Mn/Al ratio of the sediments, as an indicator of the reduction reactions, also supports the results.
In this presentation, we will discuss the land-sea material cycle in the TDSC, focusing on the analysis of organic carbon and nitrogen isotope ratios in surface sediments and nutrient dynamics in seawater.