Effects of increasing temperatures on methane concentrations and methanogenesis during experimental incubation of sediments from oligotrophic and mesotrophic lakes
Effects of increasing temperatures on methane concentrations and methanogenesis during experimental incubation of sediments from oligotrophic and mesotrophic lakes
复制标题
DOI：
10.1002/2016jg003328
复制
发表时间：
2016-05-01
影响因子：
3.7
通讯作者：
Casper, Peter
中科院分区：
文献类型：
--
作者：
Fuchs, Andrea;Lyautey, Emilie;Casper, Peter
全球变暖预计将提高淡水湖的温度，淡水湖的甲烷浓度已被公认为占大气甲烷浓度的10%。温度的升高提高了甲烷的产量和氧化速率，但很少有研究考虑在湖泊沉积物中实验温度较高时这两个过程之间的平衡。研究了在4、8和12℃的好氧水中培养的完整沉积物岩芯中甲烷浓度、甲烷产生率、产甲烷(MCRA)和甲烷营养(PmoA)群落大小对温度的依赖关系。在两个温带湖泊采集了25厘米长的沉积物岩心：斯泰克林湖(德国；中营养-少营养，最大深度69.5米)和日内瓦湖(法国/瑞士，中营养，最大深度310米)。虽然斯特克林湖沉积物中甲烷的产生速率没有随着温度的升高而变化，但甲烷浓度显著下降。相反，日内瓦湖沉积物中20-25厘米的甲烷产生率随着温度的升高而增加，但甲烷浓度没有变化。实时荧光定量聚合酶链式反应显示，产甲烷和营养甲烷的群落大小与培养温度无关。斯特克林湖的甲烷浓度和群落规模比日内瓦湖高1-2个数量级，而24小时后两湖的潜在甲烷生产量相似，平均分别为2.5和1.9nmolg(-1)DWH(-1)。我们的结果表明，在更高的温度下，甲烷氧化可以平衡甚至超过甲烷的产量。这表明，厌氧甲烷氧化可能以比先前预期更重要的速度参与甲烷平衡。
Global warming is expected to raise temperatures in freshwater lakes, which have been acknowledged to contribute up to 10% of the atmospheric methane concentrations. Increasing temperature enhances methane production and oxidation rates, but few studies have considered the balance between both processes at experimentally higher temperatures within lake sediments. The temperature dependence of methane concentrations, methane production rates, and methanogenic (mcrA) and methanotrophic (pmoA) community size was investigated in intact sediment cores incubated with aerobic hypolimnion water at 4, 8, and 12 degrees C over 3weeks. Sediment cores of 25cm length were collected at two temperate lakesLake Stechlin (Germany; mesotrophic-oligotrophic, maximum depth 69.5m) and Lake Geneva (France/Switzerland; mesotrophic, maximum depth 310m). While methane production rates in Lake Stechlin sediments did not change with increasing temperatures, methane concentrations decreased significantly. In contrast, methane production rates increased in 20-25cm in Lake Geneva sediments with increasing temperatures, but methane concentrations did not differ. Real-time PCR demonstrated the methanogenic and methanotrophic community size remained stable independently of the incubation temperature. Methane concentrations as well as community sizes were 1-2 orders of magnitude higher in Lake Stechlin than in Lake Geneva, while potential methane production rates after 24h were similar in both lakes, with on average 2.5 and 1.9nmolg(-1)DWh(-1), respectively. Our results suggest that at higher temperatures methane oxidation could balance, and even exceed, methane production. This suggests that anaerobic methane oxidation could be involved in the methane balance at a more important rate than previously anticipated.