Dam reservoirs in headwater catchments, as critical zones for their proximity to terrestrial sources, play important roles in dissolved organic carbon(DOC) cycling. However, the effects of ecosystem metabolism(EM) on ...Dam reservoirs in headwater catchments, as critical zones for their proximity to terrestrial sources, play important roles in dissolved organic carbon(DOC) cycling. However, the effects of ecosystem metabolism(EM) on DOC cycling are not well known. Here, in-situ diurnal and monthly observations were conducted to measure EM(including gross primary production(GPP), ecosystem respiration(ER) and heterotrophic respiration(HR)), DOC turnover and CO_(2)emissions in a headwater catchment reservoir in Southeastern China in 2020. Our study showed the nocturnal CO_(2)emission rate was about twice as high as in daytime, and was strongly driven by EM. The values for DOC turnover velocity ranged from 0.10 to 1.59 m/day,and the average DOC turnover rate was 0.13 day-1, with the average removal efficiency of 12%. The contribution of respired DOC to daily CO_(2)emissions ranged from 17% to 61%. The accumulated efficiencies were estimated to be 13% for the selected 15 reservoirs throughout the Changjiang River network, corresponding to about 0.34 Tg C/year of the respired DOC.The modified CO_(2)flux was 0.75 Tg C/year, and respired DOC accounted for about 45% of total emitted CO_(2)from the 15 larger reservoirs. Our research emphasizes the necessity of incorporating the effects of EM into studies of reservoir DOC removal and COemissions.展开更多
Background Using isotope mixing models,researchers can estimate the proportionate contributions of the components within a mixture to infer their sources,which is a significant method in fields such as ecology,environ...Background Using isotope mixing models,researchers can estimate the proportionate contributions of the components within a mixture to infer their sources,which is a significant method in fields such as ecology,environmental science,and geography.However,existing isotope mixing model applications suffer from large uncertainties,poor applicability,and cumbersome usage,necessitating the development of user-friendly applications with high precision and broad applicability for calculating isotope mixing models.We developed the IMix application that features a simple and user-friendly interface and can analyse user data to recommend suitable models.It includes six steps:(1)importing data,(2)model recommendation,(3)exporting data,(4)linear mixing model,(5)normal distribution model,and(6)optimised Bayesian model.Results IMix is an accurate and easy-to-use tool that simplifies the calculation of source partitioning using stable isotopes and eliminates the associated complexity and uncertainty.It can also automatically analyse the advantages and disadvantages of isotope mixing models and automatically select the optimal mixing model based on user data.Conclusions The simple and intuitive interface of IMix eliminates many cumbersome operations,thus helping to save user learning time and optimise the user experience.The use of IMix for the calculation of isotope mixing models can significantly enhance research efficiency.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 42077304, 41877483 and 41371454)。
文摘Dam reservoirs in headwater catchments, as critical zones for their proximity to terrestrial sources, play important roles in dissolved organic carbon(DOC) cycling. However, the effects of ecosystem metabolism(EM) on DOC cycling are not well known. Here, in-situ diurnal and monthly observations were conducted to measure EM(including gross primary production(GPP), ecosystem respiration(ER) and heterotrophic respiration(HR)), DOC turnover and CO_(2)emissions in a headwater catchment reservoir in Southeastern China in 2020. Our study showed the nocturnal CO_(2)emission rate was about twice as high as in daytime, and was strongly driven by EM. The values for DOC turnover velocity ranged from 0.10 to 1.59 m/day,and the average DOC turnover rate was 0.13 day-1, with the average removal efficiency of 12%. The contribution of respired DOC to daily CO_(2)emissions ranged from 17% to 61%. The accumulated efficiencies were estimated to be 13% for the selected 15 reservoirs throughout the Changjiang River network, corresponding to about 0.34 Tg C/year of the respired DOC.The modified CO_(2)flux was 0.75 Tg C/year, and respired DOC accounted for about 45% of total emitted CO_(2)from the 15 larger reservoirs. Our research emphasizes the necessity of incorporating the effects of EM into studies of reservoir DOC removal and COemissions.
基金funded by the National Natural Science Foundation of China(No.32301442)Natural Science Foundation of Sichuan Province(Nos.2024NSFSC0422 and 23NSFSCC0116)
文摘Background Using isotope mixing models,researchers can estimate the proportionate contributions of the components within a mixture to infer their sources,which is a significant method in fields such as ecology,environmental science,and geography.However,existing isotope mixing model applications suffer from large uncertainties,poor applicability,and cumbersome usage,necessitating the development of user-friendly applications with high precision and broad applicability for calculating isotope mixing models.We developed the IMix application that features a simple and user-friendly interface and can analyse user data to recommend suitable models.It includes six steps:(1)importing data,(2)model recommendation,(3)exporting data,(4)linear mixing model,(5)normal distribution model,and(6)optimised Bayesian model.Results IMix is an accurate and easy-to-use tool that simplifies the calculation of source partitioning using stable isotopes and eliminates the associated complexity and uncertainty.It can also automatically analyse the advantages and disadvantages of isotope mixing models and automatically select the optimal mixing model based on user data.Conclusions The simple and intuitive interface of IMix eliminates many cumbersome operations,thus helping to save user learning time and optimise the user experience.The use of IMix for the calculation of isotope mixing models can significantly enhance research efficiency.
