Bacterioneuston control of air‐water methane exchange determined with a laboratory gas exchange tank
Bacterioneuston control of air‐water methane exchange determined with a laboratory gas exchange tank
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用实验室气体交换罐测定空气-水甲烷交换的菌胞控制
DOI：
10.1029/2003gb002043
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发表时间：
2003
影响因子：
5.2
通讯作者：
N. Owens
中科院分区：
文献类型：
--
作者：
R. Upstill‐Goddard;T. Frost;Gordon R. Henry;Mark P. Franklin;J. Murrell;N. Owens
在密闭的实验室交换罐中测定了CH 4、N2 O和SF6的表观传递速度（kw）。调节罐水（纯Milli-RO ®水或在Milli-RO ®中制备的人工海水）和/或罐空气气体组成，并通过气相色谱法监测随后的气体转移。导出的kw被转换为“表观k600”，即20°C时淡水中CO2的值。对于CH 4，分析限制排除了基于罐空气测量值估计表观k600。在一些实验中，我们加入了活的甲烷氧化菌菌株。在其他实验中，我们添加了化学失活的甲烷氧化菌、非CH 4氧化剂（弧菌）或细菌相关的表面活性剂作为对照。对于所有个体对照，从CH 4、N2 O或SF6估计的表观k600是不可区分的。然而，侵入性的估计总是超过逃避性的估计，这意味着气泡对气体侵入的一些控制。甲烷氧化菌菌株之间的表观k600估计值差异显著，可能反映了物种特异性表面活性剂释放。对于气体侵入过程中的单个菌株，从CH 4、N2 O或SF6估计的表观k600是不可区分的，而在气体逃逸过程中，k600-CH 4显著高于k600-N2 O或k600-SF6，两者是相同的。因此，回避性k600-CH 4/k600-SF6总是显著高于1，而侵入性k600-CH 4/k600-SF6与1没有显著差异。同样，对照组的k600-CH 4/k600-SF6和所有实验的k600-N2 O/k600-SF6与1无显著差异。我们的结果与通过在罐微层中添加甲烷氧化菌对CH 4交换的主动代谢控制一致，对k600-CH 4的增强为12 ± 10%。因此，反应性示踪气体通量确定的常规示踪剂方法在海上可能是错误的，促使需要详细研究的海洋表面微层中的气体交换的作用。
The apparent transfer velocities (kw) of CH4, N2O, and SF6 were determined for gas invasion and evasion in a closed laboratory exchange tank. Tank water (pure Milli‐RO® water or artificial seawater prepared in Milli‐RO®) and/or tank air gas compositions were adjusted, with monitoring of subsequent gas transfer by gas chromatography. Derived kw was converted to “apparent k600,” the value for CO2 in freshwater at 20°C. For CH4, analytical constraints precluded estimating apparent k600 based on tank air measurements. In some experiments we added strains of live methanotrophs. In others we added chemically deactivated methanotrophs, non‐CH4 oxidizers (Vibrio), or bacterially associated surfactants, as controls. For all individual controls, apparent k600 estimated from CH4, N2O, or SF6 was indistinguishable. However, invasive estimates always exceeded evasive estimates, implying some control of gas invasion by bubbles. Estimates of apparent k600 differed significantly between methanotroph strains, possibly reflecting species‐specific surfactant release. For individual strains during gas invasion, apparent k600 estimated from CH4, N2O, or SF6 was indistinguishable, whereas during gas evasion, k600‐CH4 was significantly higher than either k600‐N2O or k600‐SF6, which were identical. Hence evasive k600‐CH4/k600‐SF6 was always significantly above unity, whereas invasive k600‐CH4/k600‐SF6 was not significantly different from unity. Similarly, k600‐CH4/k600‐SF6 for the controls and k600‐N2O/k600‐SF6 for all experiments did not differ significantly from unity. Our results are consistent with active metabolic control of CH4 exchange by added methanotrophs in the tank microlayer, giving enhancements of ∼12 ± 10% for k600‐CH4. Hence reactive trace gas fluxes determined by conventional tracer methods at sea may be in error, prompting a need for detailed study of the role of the sea surface microlayer in gas exchange.