Nitrous Oxide Emissions From Drying Streams and Rivers. Issue 24 (21st December 2021)

• Record Type: Journal Article
• Authors: Tonina, D.; Marzadri, A.; Bellin, A.; Dee, M. M.; Bernal, S.; Tank, J. L.
• Is Part Of: Geophysical research letters. Volume 48:Issue 24(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-21
• Subjects: climate change -- land use -- drought -- nitrous oxide emissions; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL095305
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Streams and rivers are suffering more extreme and prolonged low flows than those naturally occurring without human intervention with potential relevant worldwide effects on the production of nitrous oxide (N2 O), a greenhouse gas 300 times more potent than carbon dioxide. Here, we address the question of whether droughts and management‐induced low flows increase riverine N2 O emissions causing positive feedback in response to climate change. Supported by field data, we model riverine N2 O emissions for decreasing mean summer flows in a forested and agricultural watershed under chemostatic and chemodynamic dissolved inorganic reactive nitrogen (DIN) concentrations. Our results demonstrate that total N2 O emissions decrease with increasing low flow severity in both watersheds regardless of DIN scenario; which imparts a form of climate resilience. Plain Language Summary: Emissions of the ozone‐layer destructor and potent greenhouse gas nitrous oxide, N2 O, from rivers are a function of both nitrate loads and stream flows. Here we answer the question of whether droughts and subsequent low flows may exacerbate climate change by increasing N2 O emissions, thus forming positive feedback, which may self‐reinforce the adverse effects of climate change. We demonstrate that total N2 O emissions may remain similar or decrease with decreasing flows in both agricultural and forested watersheds. The reduction is mainly due to reduced water surface areas. However, N2 O emissions per stream water surface unit area significantly increase in agricultural reaches due to both high nitrate concentrations and their morphological characteristics but remain constant or decrease in reaches flowing in forested watersheds. Key Points: Low flows lead to higher N2 O emission per unit stream area in agricultural but not in forested reaches Total riverine N2 O emissions decrease with low flow severity regardless of land use Increasing low flow severity does not induce positive feedback to climate change due to N2 O emissions