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Seasonal patterns in greenhouse gas emissions from lakes and ponds in a High Arctic polygonal landscape
Limnology and Oceanography ( IF 4.5 ) Pub Date : 2021-01-20 , DOI: 10.1002/lno.11660
Vilmantas Prėskienis 1, 2 , Isabelle Laurion 1, 2 , Frédéric Bouchard 1, 2, 3 , Peter M. J. Douglas 4 , Michael F. Billett 5 , Daniel Fortier 2, 6 , Xiaomei Xu 7
Affiliation  

Lakes and ponds can be hotspots for CO2 and CH4 emissions, but Arctic studies remain scarce. Here we present diffusive and ebullition fluxes collected over several years from 30 ponds and 4 lakes formed on an organic‐rich polygonal tundra landscape. Water body morphology strongly affects the mixing regime—and thus the seasonal patterns in gas emissions—with ice‐out and autumnal turnover periods identified as hot moments in most cases. The studied thermokarst lake maintained relatively high ebullition rates of millennia‐old CH4 (up to 3405 14C YBP). Larger and deeper kettle lakes maintained low fluxes of both gases (century to millennium‐old), slowly turning into a CO2 sink over the summer. During winter, lakes accumulated CO2, which was emitted during the ice‐out period. Coalescent polygonal ponds, influenced by photosynthesizing benthic mats, were continuous CO2 sinks, yet important CH4 emitters (modern carbon). The highest fluxes were recorded from ice‐wedge trough ponds (up to 96 mmol CO2 equivalent m−2 d−1). However, despite clear signs of permafrost carbon inputs via active shore erosion, these sheltered ponds emitted modern to century‐old greenhouse gases. As the ice‐free period lengthens, scenarios of warmer and wetter conditions could favor both the production of CO2 and CH4 from thawing permafrost carbon, and CH4 production from recently fixed carbon through an atmospheric CO2‐to‐CH4 shunt at sites in which primary production is stimulated. This must be carefully considered at the landscape scale, recognizing that older carbon stocks can be mineralized efficiently in specific locations, such as in thermokarst lakes.

中文翻译:

高北极多角形景观中湖泊和池塘温室气体排放的季节性模式

湖泊和池塘可能是CO 2和CH 4排放的热点,但是北极研究仍然很少。在这里,我们介绍了几年来从形成于富含有机物的多边形苔原景观上的30个池塘和4个湖泊中收集的扩散和沸腾通量。水体形态极大地影响了混合方式,进而影响了气体排放的季节性模式,在大多数情况下,结冰和秋季周转期被确定为高温时刻。所研究的喀斯特喀斯特湖保持了较高的千年历史CH 4沸腾速率(高达3405 14 C YBP)。更大,更深的水壶湖使两种气体的通量保持较低水平(百年​​至千禧年),并逐渐转化为CO 2在夏天下沉。在冬季,湖泊积聚了CO 2,该CO 2是在冰期释放的。受光合作用底栖垫影响的聚结多边形池塘是连续的CO 2汇,但仍是重要的CH 4排放源(现代碳)。记录到来自冰楔槽池塘的最高通量(高达96 mmol CO 2当量m -2 d -1)。但是,尽管有明显迹象表明永久性侵蚀是由于永久性海岸侵蚀造成的多年冻土碳输入,但这些有遮盖的池塘还是排放了近百年前的温室气体。随着无冰期的延长,气候变暖和潮湿的情况可能会同时有利于CO 2和CH 4的产生从融化永冻土碳和CH 4通过大气中的CO产量从最近的固定碳2 -to-CH 4的位点处的分流,其中初级生产被刺激。必须认识到这是在景观尺度上要考虑的,因为认识到较旧的碳库可以在特定的位置(例如喀斯特喀斯特湖)中有效地矿化。
更新日期:2021-01-20
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