Nitrous oxide sinks and emissions in boreal aquatic networks in Quebec

作者：Soued C; del Giorgio P A; Maranger R^*

来源：Nature Geoscience, 2016, 9(2): 116-+.

DOI：10.1038/NGEO2611

Inland waters are important sites of nitrogen processing(1,2), and represent a significant component of the global budget of nitrous oxide(3), a powerful greenhouse gas(4). Measurements have focused on nitrogen-rich temperate rivers, with low-nitrogen freshwater systems at high latitudes receiving less attention. Here we measured surface water nitrous oxide partial pressures and calculated fluxes across 321 rivers, lakes and ponds in three boreal regions of Quebec, Canada. Fluxes to the atmosphere ranged from -23.1 to 115.7 mu mol m(-2) d(-1), with high variability among ecosystem types, regions and seasons. Surprisingly, over 40% of the systems sampled were under-saturated in nitrous oxide during the summer, and one region's aquatic network was a net atmospheric sink. Fluxes could not be predicted from the relatively narrow range in nitrogen concentrations, but the aquatic systems acting as sinks tended to have lower pH, higher dissolved organic carbon and lower oxygen concentrations. Given the large variability in observed fluxes, we estimate that high-latitude aquatic networks may emit from -0.07 to 0.20 Tg N2O-N yr(-1). The potential of boreal aquatic networks to act as net atmospheric nitrous oxide sinks highlights the extensive uncertainty in our understanding of global freshwater nitrous oxide budgets.

• 出版日期2016-2