Stream dissolved organic matter in permafrost regions shows surprising compositional similarities but negative priming and nutrient effects

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Wologo, E., Shakil, S., Zolkos, S., Textor, S., Ewing, S., Klassen, J., et al. (2021). Stream dissolved organic matter in permafrost regions shows surprising compositional similarities but negative priming and nutrient effects. Global Biogeochemical Cycles, 35, e2020GB006719. https://doi.org/10.1029/2020GB006719

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Title: Stream dissolved organic matter in permafrost regions shows surprising compositional similarities but negative priming and nutrient effects
Author: Wologo, Ethan; Shakil, Sarah; Zolkos, Scott; Textor, Sadie; Ewing, Stephanie; Klassen, Jane; Spencer, Robert G. M.; Podgorski, David C.; Tank, Suzanne E. T.; Baker, Michelle A.; O'Donnell, Jonathan A.; Wickland, Kimberly P.; Foks, Sydney S. W.; Zarnetske, Jay P.; Lee-Cullin, Joseph; Liu, Futing; Yang, Yuanhe; Kortelainen, Pirkko; Kolehmainen, Jaana; Dean, Joshua F.; Vonk, Jorien E.; Holmes, Robert M.; Pinay, Gilles; Powell, Michaela M.; Howe, Jansen; Frei, Rebecca J.; Bratsman, Samuel P.; Abbott, Benjamin W.
Publisher: American Geophysical Union
Date: 2021
Language: en
Belongs to series: Global Biogeochemical Cycles 35 (1), e2020GB006719
ISSN: 0886-6236
DOI: https://doi.org/10.1029/2020GB006719
URI: http://hdl.handle.net/10138/336834
Abstract: Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28-day incubations. We incubated late-summer stream water from 23 locations nested in seven northern or high-altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems and that quantifying two-way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways.
Subject: permafrost
cryosphere and high-latitude processes
thermokarst
rivers
carbon cycling
nutrients
nutrients and nutrient cycling
organic matter
permafrost regions
compositional similarities
nutrient effects
geosciences
Subject (ysa): ikirouta
joet
hiilen kierto
ravinteet
ravinteiden kierrätys
orgaaninen aines
vaikutukset
1171 Geotieteet
Rights: CC BY 4.0


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