Observational studies of the effects of wind mixing and biological process on the vertical distribution of dissolved oxygen off the Changjiang Estuary

Wind mixing is important in regulating dissolved oxygen (DO) variability; however, the transect response of DO dynamics to wind disturbance has seldom been documented with field data. In summer 2017, repeat observations off Changjiang Estuary were conducted throughout a fresh (the maximum speed was 9.8 m s–1) event reveal role physical and biological activity variations. After event, hypoxia alleviated presenting as thickness decreased from 30 20 m. However, poorly ventilated near-bottom aggravated further decrease DO. Generally, saturation (DOs) depth-integrated water column increased by 9%–49% through diffusion weakened stratification enhanced phytoplankton bloom. this case, wind-induced mass transporting downward had limited contribution water-column budget, while upwards nutrients induced fueled larger vertical area algae bloom subsequent substantial consumption. As increased, air-sea exchange would be supplying DO, especially nearshore areas, which could effectively offset deficiency. summary, frequently occurring wind-mixing events alleviate but probably exacerbate at bottom, determined competing ventilation respiration roles. Such complex interactions likely occur perform differently stress varies. Thus, high-spatial long-term process are required better understand net effects bottom evolution.