Stream metabolism sources a large fraction of carbon dioxide to the atmosphere in two hydrologically contrasting headwater streams
Stream metabolism sources a large fraction of carbon dioxide to the atmosphere in two hydrologically contrasting headwater streams
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溪流代谢将大部分二氧化碳通过两条水文截然不同的源头溪流排放到大气中
DOI：
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发表时间：
2022
影响因子：
4.5
通讯作者：
A. Lupon
中科院分区：
文献类型：
--
作者：
S. Bernal;M. Cohen;J. Ledesma;Lily Kirk;E. Martí;A. Lupon
源流是向大气排放二氧化碳（CO2）的控制点，人们普遍认为侧向地下水输入对CO2排放通量的相对贡献超过了流内代谢过程。本文分析了地中海两条源头河流春季和初夏连续测量的溶解CO2和氧（O2）浓度，并以此评估了河流中净生态系统产量（NEP）对CO2排放的贡献。这两条河流表现出截然不同的水文状况：一条是非多年生的，地下水流入相对较少，而另一条是多年生的，地下水侧向输入显著。非多年生流在瞬时和每日CO2和O2浓度之间表现出强烈的负耦合，尽管持续存在负NEP，但有氧生态系统呼吸（ER）与总初级生产量（GPP）之间存在强烈的相关性。在多年生流中，CO2-O2随时间变化较大，ER与GPP不相关，NEP随温度升高呈持续负相关。在非多年生和多年生河流中，平均NEP对CO2排放的贡献分别为51%和57%。尽管这些比例随代谢化学计量学和地下水二氧化碳浓度的假设而变化，但在两条河流中，河流中的二氧化碳产量始终一致且实质性地贡献了大气总二氧化碳通量。我们得出的结论是，在一些水源溪流中，溪流代谢对驱动碳循环的作用可能比之前假设的更重要。
Headwater streams are control points for carbon dioxide (CO2) emissions to the atmosphere, with relative contributions to CO2 emission fluxes from lateral groundwater inputs widely assumed to overwhelm those from in‐stream metabolic processes. We analyzed continuous measurements of stream dissolved CO2 and oxygen (O2) concentrations during spring and early summer in two Mediterranean headwater streams from which we evaluated the contribution of in‐stream net ecosystem production (NEP) to CO2 emission. The two streams exhibited contrasting hydrological regimes: one was non‐perennial with relatively small groundwater inflows, while the other was perennial and received significant lateral groundwater inputs. The non‐perennial stream exhibited strong inverse coupling between instantaneous and daily CO2 and O2 concentrations, and a strong correlation between aerobic ecosystem respiration (ER) and gross primary production (GPP) despite persistent negative NEP. At the perennial stream, the CO2–O2 relationship varied largely over time, ER and GPP were uncorrelated, and NEP, which was consistently negative, increased with increasing temperature. Mean NEP contribution to CO2 emission was 51% and 57% at the non‐perennial and perennial stream, respectively. Although these proportions varied with assumptions about metabolic stoichiometry and groundwater CO2 concentration, in‐stream CO2 production consistently and substantially contributed to total atmospheric CO2 flux in both streams. We conclude that in‐stream metabolism can be more important for driving C cycling in some headwater streams than previously assumed.
DOI：
10.1073/pnas.2106322119
发表时间：
2022-03-15
影响因子：
11.1
作者：
Liu S;Kuhn C;Amatulli G;Aho K;Butman DE;Allen GH;Lin P;Pan M;Yamazaki D;Brinkerhoff C;Gleason C;Xia X;Raymond PA
通讯作者：
Raymond PA
从哥斯达黎加新热带源头水流中成对的 O2-CO2 气体测量中划分无机碳通量
影响因子：
4
作者：
Marzolf, Nicholas S.;Small, Gaston E.;Oviedo-Vargas, Diana;Ganong, Carissa N.;Duff, John H.;Ramírez, Alonso;Pringle, Catherine M.;Genereux, David P.;Ardón, Marcelo
通讯作者：
Ardón, Marcelo