Yedoma: an overlooked source of nitrous oxide (N2O) from the Arctic? (Yedoma-N)

Principal investigator: Assoc. Prof. Christina Biasi

Funding period: 2015-2019 (Finnish Academy)

Arctic ecosystems are thought to be a negligible source for the strong greenhouse gas nitrous oxide (N2O). This view contrasts recent findings on high N2O emissions associated with permafrost melting and frost-action. The discovery that N2O can be released from the cold Arctic biome justifies searching for other N2O sources in this region. Based on our current knowledge of factors controlling N2O emissions from soils, we identified Yedoma deposits as a prime candidate. Yedoma deposits are organic-rich Pleistocene deposits which store about one third of organic matter held in Arctic permafrost. Yedoma is known to be very vulnerable towards carbon release but has not yet been investigated in terms of N2O production. This is surprising, since they are rich in nitrogen and several soil and environmental conditions of Yedoma are highly suitable for N2O production (e.g. high nutrient levels, low C/N ratio, eroded surfaces lacking plants, labile organic matter; permafrost thawing).

Here, we comprehensively research into the potential of Yedoma soils to emit N2O (in laboratory and field experiments) and explore a new frontier in polar science: the possibility that certain Arctic soils release significant amounts of the strong greenhouse gas N2O. The overarching objective of this study is to identify Yedoma soils as sources of N2O in the Arctic and quantify the emissions rates using comprehensive approaches at different scales. We hypothesize that Yedoma is a yet overlooked, significant source of N2O from the Arctic. In line with this major objective, multiple components of the N cycle will be assessed, which have not yet been addressed from Yedoma soils before.

The cross-disciplinary research involves national and international renowned experts in Arctic research and will link process-based ecological and trace-gas flux measurements with geospatial observations and microbial analysis. We will apply innovative field and laboratory studies together with most-modern molecular microbial and isotope analysis to quantify and better understand the N2O source strength of Yedoma. Our approach will establish a legacy of data and methodologies that has the potential to link the Arctic ecosystem with the global N2O cycle and lead to a better understanding of feedback mechanisms of one of the most vulnerable Arctic storehouses to climate warming.