Variability and drivers of CO 2 , CH 4 , and N 2 O concentrations in streams across the United States
Variability and drivers of CO 2 , CH 4 , and N 2 O concentrations in streams across the United States
复制标题
美国溪流中 CO 2 、 CH 4 和 N 2 O 浓度的变化和驱动因素
DOI：
10.1002/lno.12281
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发表时间：
2022
影响因子：
4.5
通讯作者：
Bernhardt, Emily S.
中科院分区：
文献类型：
--
作者：
DelVecchia, Amanda G.;Rhea, Spencer;Aho, Kelly S.;Stanley, Emily H.;Hotchkiss, Erin R.;Carter, Alice;Bernhardt, Emily S.
溪流和河流是大气中温室气体 (GHG) 的主要来源，因为碳和氮在运输过程中会发生转化和释放。尽管通过大量的特定地点研究和全球范围的汇编，我们对单个温室气体通量驱动因素的理解有所提高，但由于缺乏一致收集的、时间连续的温室气体及其相关驱动因素样本，我们解析气体浓度的相互关联的物理和生物地球化学驱动因素的能力受到限制。我们对国家生态观测站网络收集的此类数据集进行了首次分析，该网络涵盖美国生态气候领域的 27 条溪流和河流。 CO2 的平均浓度范围为 36.9 ± 0.88 至 404 ± 33μmol L−1，CH4 的平均浓度范围为 0.003 ± 0.0003 至 4.99 ± 0.72μmol L−1，N2O 的平均浓度范围为 0.015 至0.04μmol L−1 和之前全局编译的跨越范围。 CO2 和 CH4 均受到物理驱动因素的强烈影响，包括平均气温和河流坡度，以及溶解氧和总氮浓度。 N2O 与总氮浓度完全相关。结果表明，气体交换的潜力主导了地点水平的气体浓度模式，但河流内有氧和厌氧代谢以及地下水的贡献也可能因地点而异。最高的气体浓度和最高的变异性发生在低梯度、温暖和非常年系统中。这些结果是提供前所未有的、连续的温室气体通量估计的第一步，这些温室气体通量受到温室气体产生的时间变化的物理和生物地球化学驱动因素的限制。
Streams and rivers are major sources of greenhouse gases (GHGs) to the atmosphere, as carbon and nitrogen are converted and outgassed during transport. Although our understanding of drivers of individual GHG fluxes has improved with numerous site‐specific studies and global‐scale compilations, our ability to parse out interrelated physical and biogeochemical drivers of gas concentrations is limited by a lack of consistently collected, temporally continuous samples of GHGs and their associated drivers. We present a first analysis of such a dataset collected by the National Ecological Observatory Network across 27 streams and rivers across ecoclimatic domains of the United States. Average concentrations of CO2ranged from 36.9 ± 0.88 to 404 ± 33μmol L−1, CH4from 0.003 ± 0.0003 to 4.99 ± 0.72μmol L−1, and N2O from 0.015 to 0.04μmol L−1and spanned ranges of previous global compilations. Both CO2and CH4were strongly affected by physical drivers including mean air temperature and stream slope, as well as by dissolved oxygen and total nitrogen concentrations. N2O was exclusively correlated with total nitrogen concentrations. Results suggested that potential for gas exchange dominated patterns in gas concentrations at the site level, but contributions of in‐stream aerobic and anaerobic metabolism, and groundwater also likely varied across sites. The highest gas concentrations as well as highest variability occurred in low‐gradient, warmer, and nonperennial systems. These results are a first step in providing unprecedented, continuous estimates of GHG flux constrained by temporally variable physical and biogeochemical drivers of GHG production.