It remains unclear whether coastal wetlands could maintain the expected carbon sink role since extreme climate events are predicted to occur more frequently under future climate change. Among these extreme events, extreme precipitation may cause significant changes in ecosystem carbon stocks in coastal wetlands. However, the impacts of extreme precipitation events on carbon cycle processes and the mechanisms responsible for associated changes in the ecosystem carbon balance remain uncertain. To address this issue, we investigated the effects of extreme precipitation events on the ecosystem carbon dioxide (CO₂) budget based on a 10-year eddy covariance dataset (2010-2019) at a coastal wetland in the Yellow River Delta. Results showed that this coastal wetland was a stable sink for CO₂, with the annual net ecosystem CO₂ exchange (NEE) ranged between -94.49 and -240.70 g C m⁻² yr⁻¹. Meanwhile, the interannual variability of the ecosystem CO₂ sink strength in the dry stage was linked to the vegetation condition, and it was strongly affected by extreme precipitation events in the wet stage. During the wet stage, there was a clear trend of less negative daily NEE (i.e., lower CO₂ uptake rate) in the years with extreme precipitation events occurring (extreme years) than in normal years, leading to the wet stage cumulative CO₂ uptake being 56% lower in extreme years. Eventually, the coastal wetland became a weaker annual CO₂ sink due to the prolonged impact of the extreme precipitation event. This research provides a timely study of the effect of extreme precipitation on ecosystem CO₂ budget in coastal wetlands and should be of value to researchers attempting to assess the future impact of climate change on coastal ecosystems.

目前尚不清楚沿海湿地是否能保持预期的碳汇作用，因为预计未来气候变化下极端气候事件将更频繁地发生。在这些极端事件中，极端降水可能导致沿海湿地生态系统碳储量发生显着变化。然而，极端降水事件对碳循环过程的影响以及导致生态系统碳平衡相关变化的机制仍不确定。为了解决这个问题，我们基于黄河三角洲沿海湿地的 10 年涡度协方差数据集 (2010-2019)研究了极端降水事件对生态系统二氧化碳 (CO ₂ ) 收支的影响。结果表明，该沿海湿地是 CO ₂的稳定汇, 每年净生态系统 CO ₂交换 (NEE) 介于 -94.49 和 -240.70 g C m ^-2 yr ^{-1 之间}。同时，干旱期生态系统CO ₂汇强度的年际变化与植被状况有关，湿润期受极端降水事件影响较大。在湿润期，发生极端降水事件的年份（极端年）日NEE负值（即CO ₂吸收率降低）比正常年份明显减少，导致湿润期累积CO ₂吸收在极端年份降低 56%。最终，沿海湿地变成了较弱的年 CO ₂由于极端降水事件的长期影响而下沉。这项研究及时研究了极端降水对沿海湿地生态系统 CO ₂收支的影响，对于试图评估气候变化对沿海生态系统未来影响的研究人员应该具有价值。