College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China; Research Center for Coastal Environmental Protection and Ecological Resilience, Guangdong Ocean University, Guangdong, Zhanjiang 524088, China.
College of Chemistry and Environment, Guangdong Ocean University, Zhanjiang 524088, China.
Sci Total Environ. 2024 May 10;924:171676. doi: 10.1016/j.scitotenv.2024.171676. Epub 2024 Mar 12.
Typhoons can induce variations in hydrodynamic conditions and biogeochemical processes, potentially escalating the risk of algal bloom occurrences impacting coastal ecosystems. However, the impacts of typhoons on instantaneous changes and the mechanisms behind typhoon-induced algal blooms remain poorly understood. This study utilized high-frequency in situ observation and machine learning model to track the dynamic variations in meteorological, hydrological, physicochemical, and Chlorophyll-a (Chl-a) levels through the complete Typhoon Talim landing in Zhanjiang Bay (ZJB) in July 2023. The results showed that a delayed onset of algal bloom occurring 10 days after typhoon's arrival. Subsequently, as temperatures reached a suitable range, with an ample supply of nutrients and water stability, Chl-a peaked at 121.49 μg L in algal bloom period. Additionally, water temperature and air temperature decreased by 1.61 °C and 2.8 °C during the typhoon, respectively. In addition, wind speed and flow speed increased by 1.34 and 0.015 m s h to peak values, respectively. Moreover, the slow decline of 8.2 % in salinity suggested a substantial freshwater input, leading to an increase in nutrients. For instance, the mean DIN and DIP were 2.2 and 8.5 times higher than those of the pre-typhoon period, resulting in a decrease in DIN/DIP (closer to16) and the alleviation of P limitation. Furthermore, pH and dissolved oxygen (DO) were both low during the typhoon period and then peaked at 8.93 and 19.05 mg L during the algal bloom period, respectively, but subsequently decreased, remaining lower than those of the pre-typhoon period. A preliminary learning machine model was established to predict Chl-a and exhibited good accuracy, with R of 0.73. This study revealed the mechanisms of eutrophication status formation and algal blooms occurrence in the coastal waters, providing insights into the effects of typhoon events on tropical coastal biogeochemistry and ecology.
台风会引起水动力条件和生物地球化学过程的变化，可能会增加赤潮发生的风险，从而对沿海生态系统造成影响。然而，台风对赤潮发生的瞬时变化及其诱发机制的影响仍知之甚少。本研究利用高频原位观测和机器学习模型，跟踪 2023 年 7 月台风“泰利”在湛江湾（ZJB）登陆期间气象、水文、理化和叶绿素 a（Chl-a）水平的动态变化。结果表明，赤潮在台风登陆后 10 天延迟发生。随后，随着温度达到适宜范围，营养物质充足，水动力稳定，Chl-a 在赤潮期达到 121.49μg/L 的峰值。此外，台风期间水温、气温分别降低了 1.61°C 和 2.8°C。另外，风速和流速分别增加到 1.34m/s 和 0.015m/s 的峰值。此外，盐度缓慢下降 8.2%，表明有大量淡水输入，导致营养物质增加。例如，DIN 和 DIP 的平均值分别比台风前增加了 2.2 倍和 8.5 倍，导致 DIN/DIP（接近 16）下降，磷限制缓解。此外，台风期间 pH 和溶解氧（DO）均较低，赤潮期分别达到 8.93 和 19.05mg/L 的峰值，随后下降，仍低于台风前的水平。建立了一个初步的学习机器模型来预测 Chl-a，具有较高的准确性，R 值为 0.73。本研究揭示了沿海富营养化状态形成和赤潮发生的机制，为了解台风事件对热带沿海生物地球化学和生态学的影响提供了依据。
