Stream metabolism and the open diel oxygen method: Principles, practice, and perspectives
Stream metabolism and the open diel oxygen method: Principles, practice, and perspectives
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DOI：
10.1002/lom3.10030
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发表时间：
2015-07-01
影响因子：
2.7
通讯作者：
Manson, J. Russell
中科院分区：
文献类型：
--
作者：
Demars, Benoit O. L.;Thompson, Joshua;Manson, J. Russell
对生态系统功能进行全球定量估计至关重要。其中，生态系统呼吸和光合作用有助于碳循环和能量流向食物网。这些可以用明渠日氧法（单站或两站）在溪流中估计，基本上依赖于在规定范围内的氧质量平衡。该方法通常被认为是低成本和易于应用于新的无漂移光学传感器。然而，它仍然具有挑战性的几个关键问题：在空气-水界面的气体传输的测量，适当的混合示踪剂，不确定性传播的计算，空间异质性的氧浓度，净初级生产力（NPP）或自养呼吸的推导，以及光合作用和呼吸的温度依赖性。一个非常简单的建模工具是在一个Excel工作簿推荐的教学方法的基本原则。Demars等人的方法是唯一能够处理河流空间异质性的方法。提供了示例数据、Excel工作簿和R脚本来运行河流代谢计算。直接气体交换的测定是必不可少的浅湍流，但建模可能更准确的大（深）河流。应避免横向流入，或明确说明横向流入的性质。最近发展了新的方法，利用多个昼夜氧曲线来估算NPP。代谢估计值不应进行系统的温度校正以比较流。其他最近的进展显着改善了开放通道昼夜氧的方法，特别是在白天呼吸的估计。
Global quantitative estimations of ecosystem functions are vital. Among those, ecosystem respiration and photosynthesis contribute to carbon cycling and energy flow to food webs. These can be estimated in streams with the open channel diel oxygen method (single or two stations) essentially relying on a mass balance of oxygen over a defined reach. The method is generally perceived as low cost and easy to apply with new drift free optic sensors. Yet, it remains challenging on several key issues reviewed here: measurements of gas transfer at the air-water interface, appropriate mixing of tracers, uncertainty propagation in the calculations, spatial heterogeneity in oxygen concentrations, the derivation of net primary production (NPP) or autotrophic respiration, and the temperature dependence of photosynthesis and respiration. An extremely simple modeling tool is presented in an Excel workbook recommended for teaching the basic principles of the method. The only method able to deal with stream spatial heterogeneity is the method by Demars et al. Example data, Excel workbook, and R script are provided to run stream metabolism calculations. Direct gas exchange determination is essential in shallow turbulent streams, but modeling may be more accurate in large (deep) rivers. Lateral inflows should be avoided or well characterized. New methods have recently been developed to estimate NPP using multiple diel oxygen curves. The metabolic estimates should not be systematically temperature corrected to compare streams. Other recent advances have improved significantly the open channel diel oxygen method, notably the estimation of respiration during daylight hours.