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Drivers of Methane Flux Differ Between Lakes and Reservoirs, Complicating Global Upscaling Efforts
Journal of Geophysical Research: Biogeosciences ( IF 3.7 ) Pub Date : 2021-03-25 , DOI: 10.1029/2019jg005600
B. R. Deemer 1 , M. A. Holgerson 2, 3
Affiliation  

Methane is an important greenhouse gas with growing atmospheric concentrations. Freshwater lakes and reservoirs contribute substantially to atmospheric methane concentrations, but the magnitude of this contribution is poorly constrained. Uncertainty stems partially from whether the sites currently sampled represent the global population as well as incomplete knowledge of which environmental variables predict methane flux. Thus, determining the main drivers of methane flux across diverse waterbody types will inform more accurate upscaling approaches. Here we use a new database of total, diffusive, and ebullitive areal methane emissions from 313 lakes and reservoirs (ranging in surface area from 6 m2 to 5,400 km2) to identify the best predictors of methane emission. We found that the best predictors of methane emission differed by waterbody type (lakes vs. reservoirs), and that ecosystem morphometric variables (e.g., surface area and maximum depth) were more important predictors in lakes whereas metrics of autochthonous production (e.g., chlorophyll a) were more important in reservoirs. We also found that productivity strongly predicted methane ebullition, whereas ecosystem morphometry and waterbody type were more important predictors of diffusive methane flux. Finally, we identify several knowledge gaps that limit upscaling efforts. First, we need more methane emission measurements in small reservoirs, large lakes, and both natural and artificial ponds. Additionally, more accurate upscaling efforts require improved global information about waterbody surface area, waterbody type (lake vs. reservoir), ice phenology, and the distribution of productivity‐related predictor variables such as total phosphorus, DOC, and chlorophyll a.

中文翻译:

湖泊和水库之间甲烷通量的驱动因素不同,使全球扩大规模的努力复杂化

甲烷是一种重要的温室气体,大气浓度不断增加。淡水湖泊和水库对大气中的甲烷浓度有很大贡献,但是这种贡献的程度受到的约束很有限。不确定性部分源于当前采样的站点是否代表全球人口以及对哪些环境变量可预测甲烷流量的不完全了解。因此,确定跨不同水体类型的甲烷通量的主要驱动因素将为更准确的放大方法提供参考。在这里,我们使用了一个新的数据库,该数据库包含313个湖泊和水库的总,扩散和沸腾的甲烷排放量(范围从6 m 2到5,400 km 2),以确定最佳的甲烷排放预测指标。我们发现,甲烷排放的最佳预测因子因水体类型(湖泊与储层)的不同而不同,并且生态系统形态变量(例如,表面积和最大深度)在湖泊中是更重要的预测因子,而自发生产的度量标准(例如,叶绿素a)在水库中更为重要。我们还发现,生产力强烈预测了甲烷沸腾,而生态系统形态和水体类型是甲烷扩散通量的更重要预测因子。最后,我们确定了限制升级工作的几个知识差距。首先,我们需要在小型水库,大型湖泊以及天然和人工池塘中进行更多的甲烷排放量测量。此外,更精确的升级工作需要关于水体表面积,水体类型(湖泊与水库),冰物候学以及与生产率相关的预测变量(例如总磷,DOC和叶绿素a)的分布的整体信息
更新日期:2021-04-11
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