近岸底层水体低氧沉积记录研究进展

Research Advances in Sedimentary Records of Coastal Bottom-water Hypoxia

长时间尺度的沉积记录可以提升对近岸低氧形成机制的理解,从而为预报、预测和发展减缓低氧措施等提供必要的依据。综述了近岸低氧发育与演化历史的主要研究进展,尤其侧重于沉积记录的研究。首先按水体受限程度将近岸低氧发育环境划分为半封闭型海盆/海湾和开阔陆架海2类,分别探讨了二者低氧发育的主要特征。其次分析总结了低氧沉积记录的替代性指标,包括对水体氧化还原环境具有较好指示意义的生物学、矿物学和地球化学指标,着重分析了各类替代性指标的适用性。最后对长江口外海域底层水体低氧发生机制与沉积记录的研究现状作了回顾与分析。目前长时间尺度的低氧沉积记录研究仍然较少,鉴于长江口外海域低氧的动态发育特征,提出了多钻孔、多参数结合的研究方案。

Sedimentary records are potential to provide long-term evidence for better understanding the development mechanism of coastal hypoxia,shedding some light on the forecast,prediction and controlling-measure development to mitigate hypoxia. Therefore,recent research advances in the formation mechanism and evolution history of coastal hypoxia were briefly reviewed,specially with focus on sedimentary records and proxy methods. First,marine environments with hypoxia were classified into semi-enclosed marginal sea / gulf and open shelf sea based on the degree of bottom-water circulation and ventilation,and main characteristics for the hypoxic development were discussed respectively. Secondly,the methodology was reviewed in the efficiency by using different proxies to reconstruct hypoxia development history from sediment cores,including redox indicators of sedimentology,biology,mineralogy and geochemistry. Ultimately,recent research advance in hypoxic development mechanism and evolution history off the Changjiang Estuary were summarized. It is worth noting that long-term evolution history has been less studied from long cores. It is therefore suggested that a synthetic methodology involving multi-core comparison with different-proxy interpretation should be employed to study the development history of seasonal hypoxia off the Changjiang Estuary.