Interannual Variability of Hydrochemical Parameters in the Kuril Area of the Northwest Pacific

To identify trends in the interannual variability of hydrochemical parameters in the Northwest Pacific, data from 10 expeditions of the research vessel “TINRO” during the summer period (June) from 2014 to 2023 were analyzed, focusing on changes in oxygen content and concentrations of nutrients along a transect through the Kuril Islands. A significant trend of decreasing oxygen content was identified at depths of 500 and 1000 m, estimated at 0.06 mL/L per year. There is a tendency towards increasing concentrations of silicon and phosphorus (up to 2.17 and 0.01 μM/year at a depth of 1000 m, respectively); however, a statistically significant trend was found only for silicon at a depth of 50 m (1.78 µM/year). These trends are consistent with the concept of deoxygenation in the North Pacific Ocean due to climate warming.