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引用本文:朱俊羽,彭凯,李宇阳,刘朝荣,周蕾,周永强,丁艳青.不同水文情景下洪泽湖二氧化碳排放通量特征及影响因素.湖泊科学,2022,34(4):1347-1358. DOI:10.18307/2022.0425
Zhu Junyu,Peng Kai,Li Yuyang,Liu Chaorong,Zhou Lei,Zhou Yongqiang,Ding Yanqing.Characteristics and influence factors of carbon dioxide efflux from Lake Hongze under different hydrological scenarios. J. Lake Sci.2022,34(4):1347-1358. DOI:10.18307/2022.0425
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不同水文情景下洪泽湖二氧化碳排放通量特征及影响因素
朱俊羽1,2, 彭凯1, 李宇阳1, 刘朝荣1, 周蕾1, 周永强1, 丁艳青2
1.中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2.中国矿业大学资源与地球科学学院, 徐州 221116
摘要:
内陆水域二氧化碳(CO2)排放是全球碳平衡的重要组成部分,全球CO2排放通量估算通常有很大不确定性,一方面源于CO2排放数据观测的时空离散性,另一方面也是缺少水文情景与CO2排放通量关联性的研究.本文观测了2018年洪泽湖不同水文情景表层水体CO2排放通量特征,并探讨其影响因素.结果表明,洪泽湖CO2排放通量为丰水期((106.9±73.4) mmol/(m2·d))>枯水期((18.7±13.6) mmol/(m2·d))>平水期((5.2±15.5) mmol/(m2·d)),且碳通量由丰(310.2~32.0 mmol/(m2·d))、枯(50.8~2.2 mmol/(m2·d))、平(-17.3~39.8 mmol/(m2·d))3种水文情景的交替表现出湖泊碳源到弱碳汇的转变,空间上CO2排放通量总体呈现北部成子湖区低、南部过水湖区高的分布趋势.洪泽湖CO2排放对水文情景响应敏感,特别是上游淮河流域来水量的改变,是主导该湖CO2排放时空分异的重要因子.丰水期湖泊接纳了淮河更多有机和无机碳的输入,外源碳基质的降解和矿化显著促进了水体CO2的生产与排放,同时氮、磷等营养物质的大量输入,加剧了水体营养化程度,进一步提高CO2排放量,间接反映出人类活动对洪泽湖CO2变化的深刻影响.平、枯水期随着上游淮河来水量的减少,驱动水体CO2排放的因素逐渐由外源输入转变为水体有机质的呼吸降解.此外,上游河口区DOM中陆源类腐殖质的累积与矿化能够促进CO2的排放,而内源有机质组分似乎并没有直接参与CO2的排放过程.研究结果揭示了水文情景交替对湖库CO2排放的重要影响,同时有必要进行高频观测以进一步明晰湖泊的碳通量变化及其控制因素.
关键词:  洪泽湖  二氧化碳通量  水文期  淮河  影响因素
DOI:10.18307/2022.0425
分类号:
基金项目:国家自然科学基金项目(41930760,41807362,41977322)、江苏省自然科学基金项目(BK20181104)、中国科学院青年创新促进会会员项目(2021312)和中国科学院南京地理与湖泊研究所青年科学家小组项目(E1SL002)联合资助.
Characteristics and influence factors of carbon dioxide efflux from Lake Hongze under different hydrological scenarios
Zhu Junyu1,2, Peng Kai1, Li Yuyang1, Liu Chaorong1, Zhou Lei1, Zhou Yongqiang1, Ding Yanqing2
1.State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China;2.School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, P. R. China
Abstract:
CO2 emission from inland waters is an important component in assessing the global carbon budgets, while the large uncertainty during the budget estimation not only results from incomplete spatial coverage of sampling sites, but also from the lack of studies on the linkages between hydrological heterogeneity of inland waters and CO2 emission. Here we examined the CO2 efflux from Lake Hongze under different hydrological scenarios in 2018, to investigate the characteristics and influencing factors of CO2. Our results indicated that the CO2 fluxes in the wet season ((106.9±73.4) mmol/(m2·d)) was significantly higher than in the dry season ((18.7±13.6) mmol/(m2·d)), and further higher in the wet-to-dry transition season ((5.2±15.5) mmol/(m2·d)). The alternation of CO2 efflux from the wet season to the dry, and further to the wet-to-dry transition season (310.2-32.0 mmol/(m2·d), 50.8-2.2 mmol/(m2·d), and -17.3-39.8 mmol/(m2·d), separately) suggested a shift from the net carbon source to a weak sink of CO2 emission from Lake Hongze. The CO2 efflux was generally low in the northern open water and high in the southern waterway region. The emission of CO2 from Lake Hongze was highly sensitive to the hydrological scenarios, especially the inflow runoff from the upstream Huaihe River to the lake. In the rainy wet season, the lake received large quantities of organic and inorganic carbon inputs from the Huaihe River. The labile inorganic carbon could be easily transformed into CO2, and the degradation and mineralization of terrestrial organic carbon could significantly promote the production and emission of CO2. The input of nitrogen, phosphorus and other nutrients enhanced the eutrophication and further increased the emission of CO2 from Lake Hongze, especially the upstream inflowing lake regions. Relatively low inflow runoff during the dry and the wet-to-dry transition seasons resulted in a prolonged water residence time and allochthonous input to autochthonous degradation of organic matter potentially favored the production of CO2 emission in the water. We further found the accumulation and degradation of terrestrial humic-like could promote CO2 emission, while autochthonous components of dissolved organic matter (DOM) were linked weakly to the process and emission of CO2. Our results demonstrate the importance of hydrological scenarios fueling the emission of CO2 from freshwater lakes, and it is necessary to conduct high-frequency observations to further clarify the efflux of CO2 from lakes and the corresponding influencing factors.
Key words:  Lake Hongze  CO2 efflux  hydrological scenarios  Huaihe River  influence factors
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