Freshwater lakes and reservoirs cover a small fraction of the Earth, however their emission of the greenhouse gas methane (CH₄) from the sediment to the atmosphere is disproportionately high. Currently, there is still a limited understanding of the links between sediment characteristics and CH₄ formation. Earlier studies have indicated that sediment age and nitrogen content are related to sediment CH₄ formation rates, but it is uncertain such relationships are valid across gradients of sediment characteristics. We therefore measured potential CH₄ formation rates in multiple layers of sediment sampled from nine lakes situated in the temperate, boreal and alpine biogeographic regions of Sweden, thus differing in productivity, catchment and climate properties. Potential CH₄ formation varied over 3 orders of magnitude, and was broadly related to the quantity and reactivity of organic matter, and generally decreased with sediment depth. Sediment age and total nitrogen content were found to be the key controlling factors of potential CH₄ formation rates, together explaining 62% of its variability. Moreover, the model developed from the Swedish lake sediment data was able to successfully predict the potential CH₄ formation rates in reservoirs situated in different biogeographic regions of Brazil (R² = 0.62). Therefore, potential CH₄ formation rates in sediments of highly contrasting lakes and reservoirs, from Amazonia to alpine tundra, could be accurately predicted using one common model (RMSE = 1.6 in ln-units). Our model provides a valuable tool to improve estimates of CH₄ emission from lakes and reservoirs, and illustrates the fundamental regulation of microbial CH₄ formation by organic matter characteristics.

中文翻译：

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预测不同生物地理区域淡水沉积物的甲烷形成率

淡水湖泊和水库覆盖了地球的一小部分，但它们从沉积物到大气中的温室气体甲烷（CH _{4 ）排放量却异常高。目前，对于沉积物特征与CH 4}形成之间的联系仍知之甚少。早期研究表明沉积物年龄和氮含量与沉积物CH ₄形成速率相关，但不确定这种关系在沉积物特征梯度上是否有效。因此，我们测量了从位于瑞典温带、北方和高山生物地理区域的九个湖泊采样的多层沉积物中潜在的 CH _{4形成速率，因此在生产力、流域和气候特性方面存在差异。}潜在的CH ₄形成变化超过3个数量级，并且与有机物的数量和反应性广泛相关，并且通常随着沉积物深度而降低。研究发现沉积物年龄和总氮含量是潜在CH ₄形成速率的关键控制因素，共同解释了62%的变异性。此外，根据瑞典湖泊沉积物数据开发的模型能够成功预测位于巴西不同生物地理区域的水库中潜在的CH _{4形成速率（} R ²  = 0.62）。因此，从亚马逊流域到高山苔原，高度对比的湖泊和水库沉积物中潜在的 CH ₄形成速率可以使用一种通用模型（RMSE = 1.6，ln 单位）准确预测。我们的模型为改进湖泊和水库CH ₄排放的估算提供了一个有价值的工具，并说明了有机物特征对微生物CH _{4形成的基本调节。}