Institute of Ecology and Genetics, University of Arhus, Ny Munkegade, Building 550, DK-8000 Arhus C, Denmark.
Appl Environ Microbiol. 1990 Sep;56(9):2902-11. doi: 10.1128/aem.56.9.2902-2911.1990.
Rates of methane emission from intact cores were measured during anoxic dark and oxic light and dark incubations. Rates of methane oxidation were calculated on the basis of oxic incubations by using the anoxic emissions as an estimate of the maximum potential flux. This technique indicated that methane oxidation consumed up to 91% of the maximum potential flux in peat sediments but that oxidation was negligible in marl sediments. Oxygen microprofiles determined for intact cores were comparable to profiles measured in situ. Thus, the laboratory incubations appeared to provide a reasonable approximation of in situ activities. This was further supported by the agreement between measured methane fluxes and fluxes predicted on the basis of methane profiles determined by in situ sampling of pore water. Methane emissions from peat sediments, oxygen concentrations and penetration depths, and methane concentration profiles were all sensitive to light-dark shifts as determined by a combination of field and laboratory analyses. Methane emissions were lower and oxygen concentrations and penetration depths were higher under illuminated than under dark conditions; the profiles of methane concentration changed in correspondence to the changes in oxygen profiles, but the estimated flux of methane into the oxic zone changed negligibly. Sediment-free, root-associated methane oxidation showed a pattern similar to that for methane oxidation in the core analyses: no oxidation was detected for roots growing in marl sediment, even for roots of Cladium jamaicense, which had the highest activity for samples from peat sediments. The magnitude of the root-associated oxidation rates indicated that belowground plant surfaces may not markedly increase the total capacity for methane consumption. However, the data collectively support the notion that the distribution and activity of methane oxidation have a major impact on the magnitude of atmospheric fluxes from the Everglades.
在缺氧黑暗和有氧光照及黑暗培养期间，测定了完整岩芯中甲烷排放的速率。基于有氧培养，利用缺氧排放来估算最大潜在通量，计算了甲烷氧化的速率。该技术表明，甲烷氧化消耗了泥炭沉积物中最大潜在通量的 91%，但在泥灰岩沉积物中氧化可忽略不计。为完整岩芯确定的氧微剖面与原位测量的剖面相当。因此，实验室培养似乎提供了对原位活动的合理近似。这进一步得到了根据原位采样孔水样确定的甲烷剖面测量的甲烷通量与预测通量之间的一致性的支持。通过现场和实验室分析的组合，泥炭沉积物中的甲烷排放、氧浓度和穿透深度以及甲烷浓度剖面均对光照-黑暗变化敏感。在光照条件下，甲烷排放量较低，氧浓度和穿透深度较高；甲烷浓度剖面的变化与氧剖面的变化相对应，但估计的甲烷通量进入有氧区变化可忽略不计。无沉积物、与根相关的甲烷氧化与岩芯分析中的甲烷氧化模式相似：在泥灰岩沉积物中生长的根没有检测到氧化，即使对于 Cladium jamaicense 的根也是如此，而 Cladium jamaicense 的根在泥炭沉积物样本中具有最高的活性。与根相关的氧化速率的大小表明，地下植物表面可能不会显著增加甲烷消耗的总容量。然而，这些数据共同支持这样一种观点，即甲烷氧化的分布和活性对大沼泽地大气通量的大小有重大影响。
