Divergent Controls on Stream Greenhouse Gas Concentrations Across a Land-Use Gradient
Divergent Controls on Stream Greenhouse Gas Concentrations Across a Land-Use Gradient
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DOI：
10.1007/s10021-020-00584-7
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发表时间：
2020-12-02
期刊：
影响因子：
3.7
通讯作者：
McDowell, William H.
中科院分区：
文献类型：
--
作者：
Herreid, Allison M.;Wymore, Adam S.;McDowell, William H.
内陆沃茨可能是大气中二氧化碳（CO2）、甲烷（CH4）和一氧化二氮（N2O）的重要来源。然而，对淡水生态系统、特别是河流的温室气体排放量的区域和全球估计仍存在相当大的不确定性。对河流中温室气体产生的控制，如水化学和沉积物特性，也知之甚少。本研究的主要目的是量化温室气体浓度的空间和时间变异性在20流景观与相当大的变化，在新英格兰，美国的土地利用和土地覆盖。溪流中的CO2、CH4和N2O始终处于过饱和状态，这表明这些小溪流是该景观中大气中温室气体的来源。结果表明，溶解的CO2，CH4和N2O的浓度不同的空间和时间模式，并在他们的关系流化学。二元和多元分析都揭示了每种气体的预测变量的独特组合，表明控制温室气体浓度的景观属性和流内过程的变化。虽然水文条件不能解释站点之间的变化，温室气体浓度的时间模式与流量和温度的季节性物候相一致。我们开发了一个概念模型，这些数据的基础上，描述了温室气体生产的空间变异性流，可以阐明每种气体的主导控制。了解河流中控制温室气体动态的因素有助于评估和预测河流生态系统如何应对气候和土地利用的变化，并可用于将河流排放纳入区域和全球温室气体排放清单。
Inland waters can be significant sources of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) to the atmosphere. However, considerable uncertainty remains in regional and global estimates of greenhouse gas (GHG) emissions from freshwater ecosystems, particularly streams. Controls on GHG production in streams, such as water chemistry and sediment characteristics, are also poorly understood. The main objective of this study was to quantify spatial and temporal variability in GHG concentrations in 20 streams across a landscape with considerable variation in land use and land cover in New England, USA. Stream water was consistently supersaturated in CO2, CH4, and N2O, suggesting that these small streams are sources of GHGs to the atmosphere in this landscape. Results show that concentrations of dissolved CO2, CH4 and N2O differed in their spatial and temporal patterns and in their relationship to stream chemistry. Both bivariate and multivariate analyses revealed a unique combination of predictor variables for each gas, suggesting variation in the landscape attributes and in-stream processes that control GHG concentrations. Although hydrologic conditions did not explain variation among sites, temporal patterns in GHG concentrations align with seasonal phenologies in flow and temperature. We developed a conceptual model based on these data that describes the spatial variability in GHG production from streams and that can elucidate the dominant controls on each gas. Developing an understanding of the factors controlling GHG dynamics in streams can help assess and predict how fluvial ecosystems will respond to changes in climate and land use and can be used to incorporate emissions from streams into regional and global GHG emission inventories.