Hypoxia in the Bohai Bay, China: distributions, causes and mechanisms

The Haihe River system is a major conduit of land-based pollution into the Bohai Sea in North China, This study presented first-ever observation hypoxia estuary, providing valuable insights complex interplay between physical and biochemical factors influencing estuarine systems. research found seasonal variations DO distribution estuaries Yongdingxin Rivers. Hypoxia emerged summer at bottom estuary dissipated autumn, with minimum concentration 1.85 mg/L recorded HH-2 station. Within hypoxic zone, average was 4.02 mg/L, saturation less than 0.4. also identified primary drivers as combination factors, water stratification due to hydrodynamic limiting exchange reoxygenation different layers. In addition, decomposition organic matter consumed significant amount dissolved oxygen.The significantly higher autumn compared suggested possible existence estuary. contribute better understanding that influence hypoxia. findings have important implications for management remediation other