Eutrophication and Dissolved Organic Matter Exacerbate the Diel Discrepancy of CO 2 Emissions in China’s Largest Urban Lake

作者：Yang Wang, Bingjie Ma, Y. Jun Xu, Shuai Shen, Xi Huang, Yan Wang, Songlin Ye, Xiaokang Tian, Yifei Zhang, Tong Wang, Siyue Li · 发表于：Environmental Science & Technology · 年份：2024 · DOI：10.1021/acs.est.4c06244 · 被引用次数：23 · 研究领域：Marine and coastal ecosystems、Aquatic Ecosystems and Phytoplankton Dynamics、Water Quality and Pollution Assessment

The large variability in the emissions of carbon dioxide (CO 2 ) from urban lakes remains a challenge for partitioning these sources at meaningful spatial and temporal scales. Dissolved organic matter (DOM) governs the spatial and temporal variations in CO 2, yet relationships of the CO 2 concentration (cCO 2 ) and emission flux (FCO 2 ) with DOM in urban lakes have rarely been reported. In this study, we monitored levels of cCO 2, FCO 2, and the composition of DOM over a 24 h period at three sites during the dry and wet seasons in China’s largest urban lake, Tangxun Lake. Our study found the ratio of day/night FCO 2 (millimoles per square meter per day) decreased from the dry season (0.79; 7.68/9.68) to the wet season (0.25; 6.05/24.16), averaging 0.42 (6.77/15.97), implying that accounting for nighttime CO 2 emissions can increase regional estimates by 70%. This study revealed that eutrophication affected diurnal CO 2 emissions with greater algal growth enhancing daytime CO 2 uptake and subsequently increasing nighttime CO 2 emissions via DOM degradation (larger protein-like DOM fraction). We anticipate that the relative magnitude of FCO 2 between day and night from lakes is likely to increase due to urbanization and climate change, underscoring the importance of treating urban lakes as a distinct group and integrating DOM dynamics into carbon cycling in future research.