底层缺氧问题严重影响长江口生态环境，并且已呈日益加重的趋势。全水柱锚系观测结果表明：台风等大风事件既可以破坏底层缺氧，也可以重建并形成比原先更严重的缺氧。该现象可能与台风后生源颗粒有机碳（POC）、陆源POC以及再悬浮POC沉降的变化有关，但目前对于台风后长江口POC通量和来源的变化，及其是否驱动台风后的缺氧现象并不十分清楚。本项目拟以时间序列漂流式沉积物捕获器为主要观测手段，分析计算台风前后1-3周长江口的POC沉降通量；通过颗粒有机碳氮同位素、生物标志物分析，构建颗粒物端元混合模型估算不同来源POC对沉降通量的贡献，甄别台风前后1-3周长江口缺氧区水柱POC主要来源及其连续变化；结合缺氧锚系连续观测，了解台风后长江口底层溶解氧连续变化，进而评估台风前后生源及陆源POC对长江口缺氧不同发展阶段的贡献，以期加深对极端天气条件下近海缺氧消失和重建过程的认识，为生态灾害的预警提供科学依据。

Hypoxia has great impact on the ecosystem and environment of the Changjiang Estuary, and the condition became worse. Mooring observations revealed that typhoons destroy hypoxia firstly, but then rebuild and exacerbate hypoxia condition. Such phenomenon was probably related to tremendous input of biological particulate organic carbon , terrestrial POC and POC from sediment resuspension. However, the POC flux and sources after typhoon, as well as their contributions to hypoxia in the Changjiang Estuary were unclear. In our proposal, we will use floating sediment trap to achieve POC flux data. End-member mixing model based on C/N isotope and biomarker will be used for POC source evolutions before and 1-2 weeks after typhoon in the Changjiang Estuary. Furthermore, mooring observations will be incorporated to reveal the bottom oxygen variations, and to explore the contributions of three POC sources to hypoxia in the Changjiang Estuary after typhoon. Our proposal will contribute to the understanding of coastal hypoxia variations during extreme weather, and lay a scientific foundation for the forecast of hypoxia.