Recent discovery of methane (CH₄) production in oxic waters challenges the conventional understanding of strict anoxic requirement for biological CH₄ production. High‐resolution field measurements in Lake Stechlin, as well as incubation experiments, suggested that oxic‐water CH₄ production occurred throughout much of the water column and was associated with phytoplankton especially diatoms, cyanobacteria, green algae, and cryptophytes. In situ concentrations and δ¹³C values of CH₄ in oxic water were negatively correlated with soluble reactive phosphorus concentrations. Using ¹³C‐labeling techniques, we showed that bicarbonate was converted to CH₄, and the production exceeded oxidation at day, but was comparable at night. These experimental data, along with complementary field observations, indicate a clear link between photosynthesis and the CH₄ production‐consumption balance in phosphorus‐limited epilimnic waters. Comparison between surface CH₄ emission data and experimental CH₄ production rates suggested that the oxic CH₄ source significantly contributed to surface emission in Lake Stechlin. These findings call for re‐examination of the aquatic CH₄ cycle and climate predictions.

中文翻译：

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光合作用驱动的含氧湖水中甲烷的产生是甲烷排放的重要因素

在含氧水中产生甲烷（CH ₄）的最新发现挑战了对生物CH ₄产生的严格缺氧要求的常规理解。Stechlin湖的高分辨率实地测量以及孵化实验表明，有氧水CH _4的产生遍及水柱的大部分区域，并且与浮游植物特别是硅藻，蓝藻，绿藻和隐生藻有关。原位浓度和δ ^13个CH的C值₄在好氧水与可溶性活性磷的浓度呈负相关。使用^13种C标记技术，我们表明碳酸氢盐已转化为CH ₄，白天的产量超过了氧化，但在晚上却相当。这些实验数据以及补充的野外观察表明，在磷受限的上表层水域中，光合作用与CH ₄生产-消费平衡之间存在明确的联系。将表面CH ₄排放数据与实验CH ₄生产率进行比较表明，有氧CH ₄源显着促进了Stechlin湖的表面排放。这些发现要求对水生CH ₄循环和气候预测进行重新检查。