When Water Vanishes: Magnitude and Regulation of Carbon Dioxide Emissions from Dry Temporary Streams
When Water Vanishes: Magnitude and Regulation of Carbon Dioxide Emissions from Dry Temporary Streams
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DOI：
10.1007/s10021-016-9963-4
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发表时间：
2016-06-01
期刊：
影响因子：
3.7
通讯作者：
von Schiller, Daniel
中科院分区：
文献类型：
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作者：
Gomez-Gener, Lluis;Obrador, Biel;von Schiller, Daniel
全球大多数河流网络都包括经常停止流动和干涸的水道。由于全球变化，这些临时水道干旱阶段的空间和时间范围正在扩大。然而，目前对河流网络碳排放的估计并未考虑干涸时的临时水道。我们通过测量干旱时期河流网络 10 个干涸河床的二氧化碳 (CO2) 通量，并将其与流动期间相同河床的 CO2 通量以及邻近高地土壤的 CO2 通量进行比较，来表征干水道碳排放的大小和变化。我们还通过检查干河床沉积物和邻近高地土壤的主要物理和化学特性来寻找调节二氧化碳排放的潜在驱动因素。干燥河床的 CO2 流出量（平均值 +/- A SD = 781.4 +/- A 390.2 mmol m(-2) day(-1)）是流动河床的 CO2 流出量（305.6 +/- A 206.1 mmol m(-2) day(-1)）的两倍，并且与高地土壤的 CO2 流出量（896.1 +/- A 263.2）相当。 mmol m(-2) 天(-1))。然而，干燥的河床沉积物和高地土壤在物理化学上是不同的，并且调节其二氧化碳流出的变量也不同。总的来说，我们的结果表明，干燥的河床构成了一个独特的、生物地球化学活跃的栖息地，可以向大气排放大量的二氧化碳。因此，忽略临时河流干燥时的二氧化碳排放可能会忽视河流网络碳平衡的关键组成部分的作用。
Most fluvial networks worldwide include watercourses that recurrently cease to flow and run dry. The spatial and temporal extent of the dry phase of these temporary watercourses is increasing as a result of global change. Yet, current estimates of carbon emissions from fluvial networks do not consider temporary watercourses when they are dry. We characterized the magnitude and variability of carbon emissions from dry watercourses by measuring the carbon dioxide (CO2) flux from 10 dry streambeds of a fluvial network during the dry period and comparing it to the CO2 flux from the same streambeds during the flowing period and to the CO2 flux from their adjacent upland soils. We also looked for potential drivers regulating the CO2 emissions by examining the main physical and chemical properties of dry streambed sediments and adjacent upland soils. The CO2 efflux from dry streambeds (mean +/- A SD = 781.4 +/- A 390.2 mmol m(-2) day(-1)) doubled the CO2 efflux from flowing streambeds (305.6 +/- A 206.1 mmol m(-2) day(-1)) and was comparable to the CO2 efflux from upland soils (896.1 +/- A 263.2 mmol m(-2) day(-1)). However, dry streambed sediments and upland soils were physicochemically distinct and differed in the variables regulating their CO2 efflux. Overall, our results indicate that dry streambeds constitute a unique and biogeochemically active habitat that can emit significant amounts of CO2 to the atmosphere. Thus, omitting CO2 emissions from temporary streams when they are dry may overlook the role of a key component of the carbon balance of fluvial networks.